JP2007285889A - Defect detection method and defect detection apparatus - Google Patents

Abstract

A defect detection method and a defect detection apparatus capable of accurately detecting a display defect such as a voltage factor defect that can be generated in an image when a voltage is applied to an image display device.
An inspection image display control unit for driving an image display device to display an inspection image with an inspection voltage value for driving in a state enabling detection of a voltage factor defect. 611, a background image display control unit 612 that displays the background image by driving the image display device with the background voltage value for driving in a state in which detection of the voltage factor defect is impossible, and an inspection image is captured. An inspection image data acquisition unit 613 that acquires inspection image data, a background image data acquisition unit 614 that captures a background image and acquires background image data, and shading correction that generates difference image data between the inspection image data and the background image data Unit 615 and a defect detection unit 616 that detects display defects based on the difference image data.
[Selection] Figure 2

Description

  The present invention provides a display defect such as a voltage factor defect that can be generated in an image when a voltage is applied to the image display device in an inspection process in manufacturing an image display device such as a liquid crystal panel or a projector that is an application product thereof. The present invention relates to a defect detection method and a defect detection apparatus that detect accurately.

Conventionally, in a display appearance inspection of a liquid crystal panel (image display device) such as a TFT (Thin Film Transistor), a display defect that appears in an image displayed on the liquid crystal panel (for example, generated in an image by applying a voltage to the liquid crystal panel) In the case of detecting possible voltage factor defects or the like) by image processing, a liquid crystal panel is imaged by an imaging device such as a CCD camera to obtain image data, and display defects are detected based on the image data.
Further, the image data acquired by the CCD camera includes shading caused by uneven illumination of the light beam irradiated on the liquid crystal panel, a decrease in the peripheral light amount of the image due to a lens, and the like. For this reason, in order to improve the display defect detection accuracy, it is necessary to remove components (shading) other than the defect components in the image data (shading correction).
The following technique has been proposed as a method for performing shading correction using image processing (see, for example, Patent Document 1).
In the technique described in Patent Document 1, background image data created in advance from image data (inspection image data) acquired by capturing an image displayed on a liquid crystal panel to be inspected with a CCD camera. The shading correction which takes the difference is adopted. Here, the background image data is obtained by taking a plurality of image data by capturing an image displayed on a liquid crystal panel that is not an inspection target with as few defects as possible, and averaging the plurality of image data.

JP 2004-226272 A

  In the technique described in Patent Document 1, the inspection image data and the background image data are acquired by capturing images displayed on different liquid crystal panels (a liquid crystal panel to be inspected and a liquid crystal panel not to be inspected). It is a thing. For this reason, when obtaining the inspection image data and the background image data, if the installation positions of the liquid crystal panels are slightly deviated, the corresponding pixels are slightly deviated. When the difference between the inspection image data and the background image data is taken, a difference cannot be obtained between corresponding pixels, and shading cannot be appropriately removed from the inspection image data. That is, display defects cannot be detected with high accuracy.

  An object of the present invention is to provide a defect detection method and a defect detection apparatus capable of accurately detecting display defects such as voltage factor defects that can be generated in an image when a voltage is applied to an image display device.

  The defect detection method of the present invention is a defect detection method for detecting a display defect of an image display device that displays an image by modulating an incident light beam for each pixel by applying a voltage having a predetermined voltage value. The image display device is driven in a state in which the voltage factor defect can be detected when a voltage factor defect that can be generated in the image when the voltage of the voltage value is applied exists in the image display device. An inspection image display step of driving the image display device with an inspection voltage value to display the inspection image on the image display device, and causing the imaging device to image the inspection image displayed on the image display device for inspection An inspection image data acquisition step for acquiring image data, and the image display device is driven in a state in which the voltage factor defect cannot be detected unlike the inspection voltage value. A background image display step of driving the image display device with the background voltage value and displaying the background image on the image display device; and causing the imaging apparatus to capture the background image displayed on the image display device. A background image data acquisition step of acquiring data, a shading correction step of taking difference between the inspection image data and the background image data for each corresponding pixel and generating difference image data, and the image based on the difference image data A defect detection step of detecting a display defect of the display device.

Here, the voltage factor defect is a case where, in an image display device, the image display device is driven at a predetermined voltage value in order to obtain a predetermined gradation value due to circuit wiring or characteristics of the circuit itself. , It means a defect at a pixel position that does not have the predetermined gradation value.
In addition, when the voltage factor defect exists in the image display device, the inspection voltage value is displayed when the same voltage value (inspection voltage value) is applied to all pixels of the image display device. Enables detection of the pixel position corresponding to the voltage factor defect in which the gradation value of the pixel position corresponding to the voltage factor defect is different from the gradation value of the surrounding pixel position in the device (pixel position and surroundings corresponding to the voltage factor defect) The voltage value can be distinguished from the pixel position. For example, a voltage value for setting an intermediate gradation value can be adopted as the inspection voltage value.
Further, the background voltage value is displayed when the voltage of the same voltage value (background voltage value) is applied to all the pixels of the image display device when a voltage factor defect exists in the image display device. In the device, the gradation value of the pixel position corresponding to the voltage factor defect is substantially the same as the gradation value of the surrounding pixel position, and the pixel position corresponding to the voltage factor defect cannot be detected (pixel corresponding to the voltage factor defect). Voltage value that makes it impossible to distinguish the position from the surrounding pixel positions. As the background voltage value, any voltage value may be used as long as it is a voltage value different from the inspection voltage value and makes it impossible to detect the pixel position corresponding to the voltage factor defect as described above. Well, it contains 0V.

  In the present invention, the inspection image and the background image are displayed on the same image display device to be inspected in the inspection image display step and the background image display step, respectively, and the image pickup apparatus inspects in the inspection image data acquisition step and the background image data acquisition step. The image and the background image are respectively captured to obtain the inspection image data and the background image data. This prevents the installation position of the image display device from being shifted when acquiring the inspection image data and the background image data. For this reason, in the shading correction step, a difference can be obtained between corresponding pixels of the inspection image data and the background image data, and difference image data in which shading is appropriately removed from the inspection image data can be generated. Therefore, in the defect detection step, the display defect of the image display device can be accurately detected based on the difference image data.

In the inspection image display step, the image display device is driven with the inspection voltage value. For this reason, in the inspection image data acquisition step, if a voltage factor defect exists in the image display device, the voltage factor defect component is included in the inspection image data.
On the other hand, in the background image display step, the image display device is driven with the background voltage value. For this reason, in the background image data acquisition step, even when a voltage factor defect exists in the image display device, the background image data does not include the voltage factor defect component (the surrounding components and the signal level (luminance value) are omitted). Will be the same).
That is, in the case where the voltage factor defect of the image display device exists, even if the inspection image data and the background image data are different between the corresponding pixels by the shading correction step, the difference image data is included in the inspection image data. The voltage factor defect component that remains is left. Therefore, in the defect detection step, display defects of the image display device, in particular, voltage factor defects can be accurately detected based on the difference image data.

  The defect detection method of the present invention is a defect detection method for detecting a display defect of an image display device that displays an image by modulating an incident light beam for each pixel by applying a voltage having a predetermined voltage value. The image display device is driven in a state in which the voltage factor defect can be detected when a voltage factor defect that can be generated in the image when the voltage of the voltage value is applied exists in the image display device. An inspection image display step of driving the image display device with an inspection voltage value to display the inspection image on the image display device, and causing the imaging device to image the inspection image displayed on the image display device for inspection An inspection image data acquisition step for acquiring image data, and the voltage requirement at one of the first background voltage values higher and lower than the inspection voltage value. A first background image display step of driving the image display device in a state in which a defect cannot be detected and displaying a first background image on the image display device; a voltage value higher than the inspection voltage value; A second background image display step of driving the image display device with the other second background voltage value of low voltage values to display a second background image on the image display device; and the image display device A background image data acquisition step of acquiring the first background image data and the second background image data by causing the imaging device to capture the first background image and the second background image respectively displayed on the imaging device; The image data and the first background image data are differentiated for each corresponding pixel to generate first difference image data, and the inspection image data and Based on the shading correction step of taking the second background image data for each corresponding pixel and generating the second difference image data, based on the first difference image data and the second difference image data, And a defect detection step of detecting a display defect of the image display device.

Here, the voltage factor defect means a defect in the pixel position due to the circuit wiring and the characteristics of the circuit itself in the image display device, as described above.
The inspection voltage value is also the same voltage value as described above. For example, a voltage value for setting an intermediate gradation value can be adopted.
Further, the first background voltage value is the same voltage value (first background voltage value) applied to all pixels of the image display device when a voltage factor defect exists in the image display device. When applied, the gradation value of the pixel position corresponding to the voltage factor defect in the image display device is substantially the same as the gradation value of the surrounding pixel position, making it impossible to detect the pixel position corresponding to the voltage factor defect (voltage). This is a voltage value that makes it impossible to distinguish between the pixel position corresponding to the factor defect and the surrounding pixel positions. As the first background voltage value, any voltage value that is different from the voltage value for inspection and that cannot detect the pixel position corresponding to the voltage factor defect as described above can be used. It may be a voltage value and includes 0V.
The second background voltage value is a voltage value higher than the inspection voltage value when the first background voltage value is a voltage value lower than the inspection voltage value. When the value is a voltage value higher than the inspection voltage value, the voltage value is lower than the inspection voltage value.

  In the present invention, the inspection image and each background image are respectively displayed on the same image display device to be inspected in the inspection image display step and each background image display step, and the imaging device is used in the inspection image data acquisition step and the background image data acquisition step. The inspection image and the background image data are acquired by causing the inspection image and the background image to be captured respectively. This prevents the installation position of the image display device from being shifted when acquiring the inspection image data and each background image data. For this reason, in the shading correction step, a difference can be obtained between the corresponding pixels of the inspection image data and each background image data, and each difference image data in which shading is appropriately removed from the inspection image data can be generated. Therefore, in the defect detection step, the display defect of the image display device can be accurately detected based on each difference image data.

In the inspection image display step, the image display device is driven with the inspection voltage value. For this reason, in the inspection image data acquisition step, if a voltage factor defect exists in the image display device, the voltage factor defect component is included in the inspection image data.
On the other hand, in the first background image display step, the image display device is driven with the first background voltage value. For this reason, in the background image data acquisition step, even when a voltage factor defect exists in the image display device, the first background image data does not include a voltage factor defect component (a surrounding component and a signal level (luminance value). ) Are substantially the same).
That is, when there is a voltage factor defect in the image display device, even if the inspection image data and the first background image data are different between corresponding pixels by the shading correction step, the first difference image data is inspected. The voltage factor defect component included in the image data remains. Therefore, in the defect detection step, the display defect of the image display device, in particular, the voltage factor defect can be accurately detected based on the first difference image data.

By the way, as a display defect of an image display device, the following white defect and black defect exist besides a voltage factor defect component.
White defects are caused by missing pixels, etc., and when the image display device is driven at a predetermined voltage value in order to obtain a predetermined luminance value for all pixels in the image display device, Means a defect at a pixel position having a high luminance value.
Black defects are caused by foreign matter or the like. In the image display device, when the image display device is driven at a predetermined voltage value in order to set all the pixels to a predetermined luminance value, the luminance value of the surrounding pixel positions. It means a defect at a pixel position having a lower luminance value.

For example, in the inspection image display step, when the image display device is driven with an inspection voltage value so that all pixels of the image display device have an intermediate gradation value, the image display device has a voltage factor defect, a white defect, and a black defect. Is present, the voltage display defect component is included in the inspection image data because the image display device is driven with the inspection voltage value. Further, since the white defect component also has a luminance value higher than the luminance value of the surrounding components, it is included in the inspection image data. Further, since the black defect component also has a luminance value lower than the luminance values of the surrounding components, it is included in the inspection image data.
Further, for example, in the first background image display step, when the image display device is driven with the first background voltage value so that all the pixels of the image display device have the minimum luminance value, the image display device has a voltage factor defect, When the white defect and the black defect exist, the image display device is driven with the first background voltage value, and thus the first background image data does not include the voltage factor defect component (the surrounding area). And the signal level (luminance value) are substantially the same). Further, since the image display device is driven so that all the pixels of the image display device have the minimum luminance value, the black defect component having a luminance value lower than the luminance value of the surrounding components is also the first background image data. (The surrounding component and the signal level (luminance value) are substantially the same). On the other hand, the white defect component having a luminance value higher than the luminance values of the surrounding components is included in the first background image data.

  That is, in the above-described case, if the inspection image data and the first background image data are differentiated between corresponding pixels by the shading correction step, the white defect included in the inspection image data in the first difference image data. The component is removed, and only the voltage factor defect component and the black defect component remain. Therefore, in the defect detection step, the voltage factor defect and the black defect of the image display device can be accurately detected based on the first difference image data, but the white defect cannot be detected.

In the present invention, for example, in the second background image display step, when the image display device is driven with the second background voltage value so that all the pixels of the image display device have the maximum luminance value, the voltage factor is applied to the image display device. When a defect, white defect, and black defect are present, the image display device is driven so that all the pixels of the image display device have the maximum luminance value. The white defect component that becomes the luminance value is not included in the second background image data (the signal level (luminance value) is substantially the same as the surrounding components).
That is, in the above-described case, if the inspection image data and the second background image data are differentiated between corresponding pixels by the shading correction step, the white defect included in the inspection image data in the second difference image data. Ingredients will remain. Therefore, in the defect detection step, the white defect of the image display device can be accurately detected based on the second difference image data.
As described above, according to the present invention, based on the first difference image data and the second difference image data, not only the voltage factor defect of the image display device but also almost all of the white defects and black defects are included. Display defects can be accurately detected.

In the defect detection method of the present invention, in the inspection image data acquisition step and the background image data acquisition step, the average values of the pixel values of all the pixels in the inspection image data and the background image data are substantially the same. It is preferable that the light receiving time during imaging by the imaging device is set to be different.
By the way, in the inspection image data acquisition step and the background image data acquisition step, the inspection voltage value for displaying the inspection image on the image display device and the background when the light receiving time at the time of imaging by the imaging device is set to be the same. Since the background voltage value for displaying an image is a different voltage value, the average values of the pixel values (luminance values) of all the pixels of the acquired inspection image data and background image data are different. Therefore, when the difference between the average values is large, it is difficult to generate differential image data in which shading is appropriately removed from the inspection image data in the shading correction step, that is, based on the differential image data in the defect detection step. It is difficult to accurately detect display defects of an image display device.
According to the present invention, the inspection image data acquisition step and the background image data acquisition step are set so that the light reception time during imaging by the imaging device is different. As a result, the average values of the pixel values (luminance values) of all the pixels of the acquired inspection image data and background image data can be made substantially the same. Therefore, it is possible to generate differential image data in which shading is appropriately removed from the inspection image data in the shading correction step, that is, even if the display defect is very small, the image display device is based on the differential image data in the defect detection step. Display defects can be accurately detected.

In the defect detection method of the present invention, in the inspection image data acquisition step and the background image data acquisition step, the average values of the pixel values of all the pixels in the inspection image data and the background image data are substantially the same. It is preferable that the amount of the incident light beam is set to be different.
By the way, in the inspection image data acquisition step and the background image data acquisition step, when the light quantity of the incident light beam to the image display device is set to be the same, an inspection voltage value for displaying the inspection image on the image display device, Since the background voltage value for displaying the background image is a different voltage value, the average values of the pixel values (luminance values) of all the pixels of the acquired inspection image data and background image data are different. Therefore, when the difference between the average values is large, it is difficult to generate differential image data in which shading is appropriately removed from the inspection image data in the shading correction step, that is, based on the differential image data in the defect detection step. It is difficult to accurately detect display defects of an image display device.
According to the present invention, in the inspection image data acquisition step and the background image data acquisition step, the amount of incident light flux to the image display device is set to be different. As a result, the average values of the pixel values (luminance values) of all the pixels of the acquired inspection image data and background image data can be made substantially the same. Therefore, it is possible to generate differential image data in which shading is appropriately removed from the inspection image data in the shading correction step, that is, even if the display defect is very small, the image display device is based on the differential image data in the defect detection step. Display defects can be accurately detected.

In the defect detection method of the present invention, the shading correction step uses a predetermined approximate expression for the level of each pixel value in each correction target image data of the inspection image data and the background image data. A correction image data generation procedure for generating corrected image data by approximating a level of each pixel value for each pixel in the other non-correction target image data of the inspection image data and the background image data, and the correction It is preferable to include a difference image data generation procedure for calculating difference for each pixel corresponding to the image data and the non-correction target image data and generating difference image data.
By the way, as described above, in the inspection image data acquisition step and the background image data acquisition step, the light receiving time at the time of imaging by the imaging device is set to be different, or the light quantity of the incident light beam to the image display device is set to be different. In this case, the average values of the pixel values of all the pixels of the inspection image data and the background image data can be combined. However, it is difficult to match the shading curve (the curvature of the luminance distribution on a predetermined line of the image), the variation in pixel values, and the like between the inspection image data and the background image data. For this reason, when the shading curve, pixel value variation, and the like differ greatly between the inspection image data and the background image data, it is difficult to generate difference image data in which shading is appropriately removed from the inspection image data in the shading correction step. That is, it is difficult to accurately detect display defects of the image display device based on the difference image data in the defect detection step.

  According to the present invention, in the corrected image data generation procedure, the level of each pixel value (luminance value) for each pixel in the correction target image data (average value of each pixel value, shading curve, variation of each pixel value, etc.) The corrected image data can be generated by approximating the level of each pixel value (luminance value) for each pixel in the non-correction target image data (average value of each pixel value, shading curve, variation of each pixel value, etc.). For this reason, the average value of each pixel value of all the pixels, the shading curve, the variation of the pixel value, and the like can be matched between the inspection image data and the background image data. Then, in the difference image data generation procedure, difference image data in which shading is appropriately removed from the inspection image data can be generated by taking the difference between the corrected image data and the non-correction target image data for each corresponding pixel. That is, even if the display defect is minute, the display defect of the image display device can be accurately detected based on the difference image data in the defect detection step.

In the defect detection method of the present invention, in the corrected image data generation procedure, each pixel value for each pixel in the corrected image data is X ′ _{(m, n),} and each pixel value for each pixel in the correction target image data is X _{1 (m, n)} , the average value of each pixel value X _{1 (m, n)} for each pixel in the correction target image data is X _1a, and each pixel value X ₁ for each pixel in the correction target image data _{(m, n)} the standard deviation of the S _1, the non-corrected pixel values for each pixel in the target image data X ₂ and _{(m, n),} each pixel value X for each pixel in the non-corrected target image data _When the average value of _{2 (m, n)} is X _2a and the standard deviation of each pixel value X _{2 (m, n)} for each pixel in the non-correction target image data is S ₂ , It is preferable to generate the corrected image data using the approximate expression (1).

According to the present invention, in the corrected image data generation procedure, the correction target image data is converted into corrected image data using the above equation (1) set with the conversion rate S ₂ / S ₁ based on the standard deviation. . As a result, in the difference image data generated by the difference image data generation procedure, it is possible to reduce variations in the pixel values in the entire difference image. For this reason, in the defect detection step, the display defect detection accuracy in the image center region in the image display device can be particularly improved based on the difference image data.

In the defect detection method of the present invention, in the corrected image data generation procedure, each pixel value for each pixel in the corrected image data is X ′ _{(m, n),} and each pixel value for each pixel in the correction target image data is X _{1 (m, n)} , the average value of each pixel value X _{1 (m, n)} for each pixel in the correction target image data is X _1a , each pixel value X ₁ for each pixel in the correction target image data _{(m, n)} the standard deviation of the S _1, the non-corrected pixel values for each pixel in the target image data X ₂ and _{(m, n),} each pixel value X for each pixel in the non-corrected target image data _When the average value of _{2 (m, n)} is X _2a and the standard deviation of each pixel value X _{2 (m, n)} for each pixel in the non-correction target image data is S ₂ , the following equation (2 It is preferable to generate the corrected image data using the approximate expression (1).

According to the present invention, the correction in the image data generation procedure, the correction target image data, by using the set above formula at a conversion of S ₂ ² / S ₁ ² Distributed (2), converts the corrected image data Yes. Thereby, in the difference image data generated by the difference image data generation procedure, the difference between the average value of each pixel value in the entire difference image and the pixel value in the image peripheral area can be reduced. For this reason, in the defect detection step, the display defect detection accuracy in the image peripheral region in the image display device can be particularly improved based on the difference image data.

  In the defect detection method of the present invention, the image display device is driven so that the outermost peripheral pixel in the image display device has a predetermined luminance value and the other pixels have a luminance value smaller than the predetermined luminance value. An outermost periphery image display step for displaying an outermost periphery image on the image display device, and an outermost periphery image data acquisition step for acquiring the outermost periphery image data by causing the imaging device to capture the outermost periphery image displayed on the image display device. And an inspection target region determination step for recognizing an outer edge position corresponding to the outermost peripheral pixel based on the outermost peripheral image data, and determining the inside of the outer edge position as an inspection target region, and the shading correction step includes: The correction target extracted image data is extracted by extracting the inspection target regions of the correction target image data and the non-correction target image data, respectively. And an inspection target region extraction procedure for generating non-correction target extraction image data. In the correction image data generation procedure, the correction image data is generated based on the correction target extraction image data and the non-correction target extraction image data. In the difference image data generation procedure, it is preferable that the difference image data is generated by taking a difference for each pixel corresponding to the correction image data and the non-correction target extraction image data.

  By the way, when the inspection image or background image displayed on the image display device is captured by the imaging device, only the inspection target area (all areas in which the inspection image and the background image are displayed) in the image display device is captured. In some cases, a part other than the inspection target region may be imaged. In this case, the inspection image data and the background image data are image data including portions other than the inspection target region in addition to the inspection target region. For this reason, for example, when generating corrected image data as described above, the correction target image data is approximated based on an average value or standard deviation including pixel values of portions other than the inspection target region (for example, the formula Since (1) and (2)) are converted into corrected image data, an average value of each pixel value, a shading curve, a variation in pixel values, and the like between inspection image data and background image data are changed. It is difficult to match. For this reason, it is difficult to generate difference image data in which shading is appropriately removed from inspection image data in the difference image data generation procedure, that is, display defects of the image display device are accurately detected based on the difference image data in the defect detection step. It is difficult to detect.

  In the present invention, the outermost peripheral image in the outermost peripheral image in the image display device is displayed on the image display device in the outermost peripheral image display step, and the outermost peripheral image in the outermost peripheral image data acquisition step is displayed on the image display device. Is captured by the imaging device to obtain the outermost peripheral image data. Further, in the inspection area determination step, a pixel position (outer edge position) having a luminance value larger than that of other pixels is recognized based on the outermost peripheral image data, and the inside of the outer edge position is determined as the inspection area. Then, in the inspection target area extraction procedure, the inspection target area of the correction target image data is extracted to generate correction target extraction image data, and the inspection target area of the non-correction target image data is extracted to generate non-correction target extraction image data. To do. As a result, in the corrected image data generation procedure, corrected image data is generated based on the correction target extraction image data and the non-correction target extraction image data, so that an average value or a standard including only each pixel value of the inspection target region is obtained. The corrected image data converted by the approximate expression based on the deviation can be generated. For this reason, it is possible to satisfactorily match the average value of each pixel value of all the pixels, the shading curve, the variation in pixel values, and the like between the inspection image data and the background image data. Therefore, in the difference image data generation procedure, by taking the difference between the corrected image data and the non-correction target extracted image data, it is possible to generate difference image data in which shading is appropriately removed from the inspection image data, that is, display defects are minute. Even if it is a thing, the display defect of an image display device can be detected accurately based on difference image data in a defect detection step.

  The defect detection apparatus of the present invention is a defect detection apparatus that detects a display defect of an image display device that displays an image by modulating an incident light beam for each pixel by applying a voltage having a predetermined voltage value, A light source device that irradiates the image display device with a light beam, an image pickup device that picks up the light beam via the image display device, and a control device that drives and controls the image display device and the image pickup device. The image display device in a state in which the voltage factor defect can be detected when a voltage factor defect component that can be generated in an image when a voltage having a predetermined voltage value is applied exists in the image display device. Unlike the inspection voltage value, the inspection image display control unit that drives the image display device with the inspection voltage value for driving the image and displays the inspection image on the image display device. A background image display control unit for driving the image display device with a background voltage value for driving the image display device in a state in which detection of a voltage factor defect is impossible and displaying a background image on the image display device An inspection image data acquisition unit for acquiring the inspection image data by causing the imaging device to capture the inspection image displayed on the image display device, and causing the imaging device to image the background image displayed on the image display device. A background image data acquisition unit that acquires background image data, a shading correction unit that generates a difference image data by taking a difference for each pixel corresponding to the inspection image data and the background image data, and based on the difference image data And a defect detection unit for detecting a display defect of the image display device.

The defect detection apparatus of the present invention is a defect detection apparatus that detects a display defect of an image display device that displays an image by modulating an incident light beam for each pixel by applying a voltage having a predetermined voltage value. A light source device that irradiates the image display device with a light beam, an image pickup device that picks up a light beam that passes through the image display device, and a control device that drives and controls the image display device and the image pickup device. The image display in a state enabling detection of the voltage factor defect when the voltage display defect exists in the image display device when a voltage having a predetermined voltage value is applied. An inspection image display controller for driving the image display device with an inspection voltage value for driving the device and displaying an inspection image on the image display device; and a voltage value higher than the inspection voltage value The image display device is driven in a state in which detection of the voltage factor defect is impossible with the first background voltage value of either one of the voltage value and the low voltage value, and the image display device has a first background. An image is displayed, and the image display device is driven by a second background voltage value that is higher or lower than the voltage value for inspection, and the image display device receives a second value. A background image display control unit that displays a background image, an inspection image data acquisition unit that acquires the inspection image data by causing the imaging device to capture the inspection image displayed on the image display device, and the image display device A background image in which the first background image data and the second background image data are acquired by causing the imaging device to respectively capture the first background image and the second background image. The data acquisition unit, the inspection image data, and the first background image data are differenced for each corresponding pixel to generate first difference image data, and the inspection image data and the second background image data A shading correction unit that calculates a difference for each corresponding pixel and generates second difference image data;
A defect detection device according to the present invention, comprising: a defect detection unit that detects a display defect of the image display device based on the first difference image data and the second difference image data. According to the above, since the defect detection method described above can be executed by the defect detection device, it is possible to enjoy the same operational effects as the defect detection method described above.

[First embodiment]
A first embodiment of the present invention will be described with reference to the drawings.
[Configuration of defect detection device]
FIG. 1 is a diagram illustrating a configuration of the defect detection apparatus 1.
The defect detection apparatus 1 is an apparatus that detects a display defect of the liquid crystal panel 10 by performing a display appearance inspection of the liquid crystal panel 10 as an image display device to be inspected. As shown in FIG. 1, the defect detection device 1 includes an optical system 2, a screen 3, a CCD camera 4 as an imaging device, a panel control device 5, and a control device 6.

  Here, the liquid crystal panel 10 to be inspected is a transmissive liquid crystal panel, and has, for example, a configuration in which liquid crystal molecules are hermetically sealed between a TFT substrate and a counter substrate. The liquid crystal panel 10 is electrically connected to the panel control device 5 in a state where the liquid crystal panel 10 is installed in a panel installation unit (not shown) in the defect detection device 1, for example, and the panel control device 5 connects the TFT substrate and the counter substrate. By applying a voltage having a predetermined voltage value (including 0 V) between them, the arrangement state of the liquid crystal molecules is changed, and a predetermined optical image is formed by transmitting or blocking the incident light beam. In the present embodiment, the liquid crystal panel 10 is configured in a normally black mode in which a black display is performed by blocking an incident light beam when no voltage is applied (voltage value is 0 V). Further, the liquid crystal panel 10 may be configured in a normally white mode in which white light is displayed by transmitting all incident light beams in a state where no voltage is applied.

The optical system 2 is an optical system that irradiates the liquid crystal panel 10 with a light beam emitted from a light source and enlarges and projects the light beam via the liquid crystal panel 10 toward the screen 3. As shown in FIG. 1, the optical system 2 includes a light source device 21, a condensing lens 22 that condenses the light emitted from the light source device 21 and irradiates the liquid crystal panel 10, and the liquid crystal panel 10. And a projection lens 23 for enlarging and projecting the optical image toward the screen 3.
Among these, the light source device 21 includes a light source lamp that performs discharge light emission and a reflector that reflects a light beam emitted from the light source lamp, although not specifically illustrated. The light beam emitted from the light source lamp is emitted toward the condenser lens 22 by the reflector.
The light source device 21 is not limited to the discharge light source device, and various solid light emitting elements such as an LED (Light Emitting Diode) element, a laser diode, an organic EL (Electro Luminescence) element, and a silicon light emitting element are adopted. Also good.

  The screen 3 is configured as a reflective screen that reflects and projects an optical image enlarged and projected by the projection lens 23. The screen 3 is not limited to a reflective screen, and may be configured as a transmissive screen that transmits and projects an incident optical image.

Under the control of the control device 6, the CCD camera 4 images the projection surface of the screen 3 and outputs a signal corresponding to the captured image to the control device 6. Although not specifically shown, the CCD camera 4 is a CCD that is an area sensor, a condensing lens that condenses the light and irradiates the CCD, and under the control of the control device 6, A shutter or the like that can change the light reception time is provided.
The CCD of the CCD camera 4 preferably has a resolution higher than that of the liquid crystal panel 10.
The panel control device 5 applies a voltage having a predetermined voltage value to the liquid crystal panel 10 under the control of the control device 6 to form a predetermined optical image on the liquid crystal panel 10.

FIG. 2 is a block diagram illustrating a schematic configuration of the control device 6.
The control device 6 is composed of, for example, a computer including a CPU (Central Processing Unit) that reads and executes a predetermined program, and controls the entire defect detection device 1. As illustrated in FIG. 2, the control device 6 includes a control unit 61 and a memory 62.
The control unit 61 is a part that executes predetermined processing (defect detection processing) in accordance with a control program stored in the memory 62, and includes an inspection image display control unit 611, a background image display control unit 612, and inspection image data acquisition. A unit 613, a background image data acquisition unit 614, a shading correction unit 615, a defect detection unit 616, and the like.

The inspection image display control unit 611 reads voltage value information related to the voltage value applied to the liquid crystal panel 10 stored in the memory 62, and performs predetermined control for driving the liquid crystal panel 10 with the inspection voltage value based on the voltage value information. The signal is output to the panel control device 5. The panel control device 5 drives the liquid crystal panel 10 with the inspection voltage value according to the control signal output from the inspection image display control unit 611, and causes the liquid crystal panel 10 to form the inspection image.
It should be noted that the inspection voltage value is the same as that when the voltage of the same voltage value (inspection voltage value) is applied to all the pixels of the liquid crystal panel 10 when the liquid crystal panel 10 has a voltage factor defect. The pixel position corresponding to the voltage factor defect is different from the gradation value of the surrounding pixel position, and the pixel position corresponding to the voltage factor defect can be detected. The voltage value can be distinguished from the pixel position, and is stored in the memory 62 in advance as voltage value information. In the present embodiment, as the voltage value for inspection, the liquid crystal panel 10 is driven such that the liquid crystal panel 10 transmits a light beam with a transmittance of 50% to form an inspection image (a gray image having an intermediate gradation value). Is set to a value.
The voltage factor defect is a predetermined voltage value for transmitting a light beam with a predetermined transmittance (with a predetermined gradation value) in the liquid crystal panel 10 due to characteristics of circuit wiring such as a TFT and the circuit itself. Even when the liquid crystal panel 10 is driven in this manner, it means a defect in a pixel position where the light beam is not transmitted with the predetermined transmittance (not having a predetermined gradation value).

The background image display control unit 612 reads voltage value information related to the voltage value applied to the liquid crystal panel 10 stored in the memory 62, and performs predetermined control for driving the liquid crystal panel 10 with the background voltage value based on the voltage value information. The signal is output to the panel control device 5. The panel control device 5 drives the liquid crystal panel 10 with the background voltage value in accordance with the control signal output from the background image display control unit 612, and causes the liquid crystal panel 10 to form a background image.
The background voltage value is determined when the same voltage value (background voltage value) is applied to all the pixels of the liquid crystal panel 10 when there is a voltage factor defect in the liquid crystal panel 10. In this case, the gradation value of the pixel position corresponding to the voltage factor defect is substantially the same as the gradation value of the surrounding pixel positions, and the pixel position corresponding to the voltage factor defect cannot be detected (pixel position corresponding to the voltage factor defect). And a surrounding pixel position are impossible) and are stored in the memory 62 in advance as voltage value information. In the present embodiment, the background voltage value is set to 0V. That is, in the present embodiment, the background image display control unit 612 outputs a control signal to the panel control device 5 to cause the liquid crystal panel 10 to perform black display.

The inspection image data acquisition unit 613 outputs a predetermined control signal to the CCD camera 4 when the inspection image is formed on the liquid crystal panel 10, and the projection surface (including the inspection image) of the screen 3 to the CCD camera 4. To image. The inspection image data acquisition unit 613 inputs an electrical signal output from the CCD camera 4 and converts it into a signal (digital signal) that can be read by a computer, and information on the pixel value (luminance value) for each pixel. Acquired inspection image data. Then, the inspection image data acquisition unit 613 stores the acquired inspection image data in the memory 62.
The background image data acquisition unit 614 outputs a predetermined control signal to the CCD camera 4 when the background image is formed on the liquid crystal panel 10 and outputs the projection surface (including the background image) of the screen 3 to the CCD camera 4. To image. The background image data acquisition unit 613 inputs an electrical signal output from the CCD camera 4 and converts it into a signal that can be read by a computer, and includes a background image including information on a pixel value (luminance value) for each pixel. Get the data. Then, the background image data acquisition unit 614 stores the acquired background image data in the memory 62.

The inspection image data acquisition unit 613 and the background image data acquisition unit 614 described above drive control the shutter in the CCD camera 4 as described below when acquiring the inspection image data and the background image data.
That is, the inspection image data acquisition unit 613 and the background image data acquisition unit 614 read speed information regarding the moving speed of the shutter (shutter speed) in the CCD camera 4 stored in the memory 62, and when the inspection image is captured by the CCD camera 4. The shutter is driven and controlled so that the light reception time of the incident light beam by the CCD differs between when the background image is captured. In this embodiment, the shutter speed of the CCD camera 4 under the drive control by the inspection image data acquisition unit 613 is set faster than the shutter speed of the CCD camera 4 under the drive control by the background image data acquisition unit 614. . The average values of the pixel values of all the pixels in the acquired inspection image data and background image data are the same by the drive control of the shutter in the CCD camera 4 by the inspection image data acquisition unit 613 and the background image data acquisition unit 614. Become.

The shading correction unit 615 calculates a difference for each corresponding pixel between the corrected image data obtained by correcting the background image data and the inspection image data (shading correction). Then, the shading correction unit 615 performs shading correction, which is caused by uneven illumination of the light beam emitted from the light source device 21 or a decrease in the peripheral light amount of the image by the lenses 22 and 23 constituting the optical system 2. Difference image data from which shading (components other than display defect components) has been removed is generated. As shown in FIG. 2, the shading correction unit 615 includes a corrected image data generation unit 6151 and a difference image data generation unit 6152.
The corrected image data generation unit 6151 reads the background image data (correction target image data) and the inspection image data (non-correction target image data) stored in the memory 62, and the level of each pixel value for each pixel in the background image data ( Each pixel value for each pixel in the inspection image data is obtained by using a predetermined approximate expression for an average value of each pixel value, a shading curve (curvature of luminance distribution on a predetermined line of the image), and a variation of each pixel value). The corrected image data is generated by approximating the level (average value of each pixel value, shading curve, variation of each pixel value). Then, the corrected image data generation unit 6151 stores the generated corrected image data in the memory 62.
The difference image data generation unit 6152 generates a difference image data by taking a difference between pixel values for each pixel corresponding to the corrected image data and the inspection image data stored in the memory 62. Then, the difference image data generation unit 6152 stores the generated difference image data in the memory 62.

The defect detection unit 616 reads the difference image data stored in the memory 62, performs a general defect enhancement process for enhancing the display defect based on the difference image data, and corresponds to a display defect such as a voltage factor defect. The pixel position is specified.
The memory 62 stores a predetermined control program, information for executing processing by the control unit 61 (voltage value information, speed information), data processed by the control unit 61, and the like.

(Defect detection method)
Next, a defect detection method using the above-described defect detection apparatus 1 will be described with reference to the drawings.
FIG. 3 is a flowchart for explaining the defect detection method.
In the following description, it is assumed that the liquid crystal panel 10 is installed in a panel installation unit (not shown) in the defect detection device 1 and the liquid crystal panel 10 and the panel control device 5 are electrically connected.
The operator operates an operation unit (not shown) of the control device 6 and performs setting input for executing defect detection of the liquid crystal panel 10. And the control part 61 of the control apparatus 6 reads the control program memorize | stored in the memory 62 according to the operation signal output from an operation part, According to a control program, as shown below, the defect of the liquid crystal panel 10 is shown. Perform detection processing.

First, the control unit 61 turns on the light source device 21 and introduces the light beam emitted from the light source device 21 into the liquid crystal panel 10 (processing ST1).
After the process ST1, the background image display control unit 612 of the control unit 61 reads out the voltage value information (background voltage value) stored in the memory 62, and displays a control signal for performing black display on the liquid crystal panel 10. Output to the control device 5. Then, the liquid crystal panel 10 blocks the incident light beam to form a black image (background image), and the background image is projected and displayed on the screen 3 (process ST2: background image display step).
After the process ST2, the background image data acquisition unit 614 of the control unit 61 outputs a predetermined control signal to the CCD camera 4 to cause the CCD camera 4 to capture the projection surface (including the background image) of the screen 3, and background image data. (Processing ST3: Background image data acquisition step). Then, the background image data acquisition unit 614 stores the acquired background image data in the memory 62.

FIG. 4 is a diagram for explaining the background image data acquisition step ST3. Specifically, FIG. 4A shows a case where the shutter speed is not adjusted (in the case of a normal shutter speed), and FIG. 4B shows a case where the shutter speed is adjusted. 4 shows an image of the projection surface (including the background image) of the screen 3 captured by the CCD camera 4. In FIG. 4, the diagram on the right side shows the pixel value for each pixel on the predetermined horizontal line HL in the diagram on the left side. That is, the horizontal axis indicates the pixel position, and the vertical axis indicates the pixel value.
Specifically, in process ST3, the background image data acquisition unit 614 reads the speed information stored in the memory 62 when acquiring the background image data, and the shutter in the CCD camera 4 at a shutter speed slower than the normal shutter speed. Is controlled. That is, the background image data acquisition unit 614 is brighter by increasing the pixel value by adjusting the shutter speed slower than when the projection surface of the screen 3 is imaged at a normal shutter speed, as shown in FIG. Get background image data.

  After the process ST3, the inspection image display control unit 611 of the control unit 61 reads the voltage value information (inspection voltage value) stored in the memory 62, and a control signal for driving the liquid crystal panel 10 with the inspection voltage value. Is output to the panel control device 5. The liquid crystal panel 10 blocks approximately half of the incident light beam (transmits substantially half) to form a gray image (inspection image) having an intermediate gradation value, and the inspection image is projected and displayed on the screen 3. (Process ST4: Inspection image display step).

  After the process ST4, the inspection image data acquisition unit 613 of the control unit 61 outputs a predetermined control signal to the CCD camera 4 to cause the CCD camera 4 to image the projection surface (including the inspection image) of the screen 3, and inspection image data. (Process ST5: inspection image data acquisition step). Then, the inspection image data acquisition unit 613 stores the acquired inspection image data in the memory 62.

FIG. 5 is a diagram for explaining the inspection image data acquisition step ST5. Specifically, FIG. 5A shows a case where the shutter speed is not adjusted (in the case of a normal shutter speed), and FIG. 5B shows a case where the shutter speed is adjusted. Further, the diagram on the left side in FIG. 5 shows an image of the projection surface (including the inspection image) of the screen 3 captured by the CCD camera 4. In FIG. 5, the diagram on the right side shows the pixel value for each pixel on the predetermined horizontal line HL in the diagram on the left side. That is, the horizontal axis indicates the pixel position, and the vertical axis indicates the pixel value.
Specifically, in process ST5, the inspection image data acquisition unit 613 reads the speed information stored in the memory 62 when acquiring the inspection image data, and the shutter in the CCD camera 4 at a shutter speed faster than the normal shutter speed. Is controlled. That is, as shown in FIG. 5, the inspection image data acquisition unit 613 is darker than the pixel value is lowered by adjusting the shutter speed faster than when the projection surface of the screen 3 is imaged at the normal shutter speed. Obtain inspection image data.
Then, as shown in FIGS. 4B and 5B, the acquired background image data and inspection image data have substantially the same average pixel values.

Here, in the process ST4, the inspection image display control unit 611 drives the liquid crystal panel 10 with the inspection voltage value. Therefore, when the liquid crystal panel 10 has a voltage factor defect, as shown in FIG. Then, a voltage factor defect component is generated at the pixel position P, and it becomes possible to distinguish from surrounding components. FIG. 5 shows a state in which the voltage factor defect component has a higher pixel value than the surrounding components, but there is also a lower state.
On the other hand, in the process ST2, since the background image display control unit 612 drives the liquid crystal panel 10 with the background voltage value (0 V), even if the voltage factor defect exists in the liquid crystal panel 10, As shown in FIG. 4, the voltage factor defect component and surrounding components are indistinguishable (the pixel value at the pixel position corresponding to the voltage factor defect is substantially the same as the pixel value at the surrounding pixel position). Become).

After processing ST5, the shading correction unit 615 of the control unit 61 performs shading correction as described below (processing ST6: shading correction step).
FIG. 6 is a diagram for explaining the shading correction step ST6. Specifically, FIG. 6A shows the inspection image data acquired in process ST5. FIG. 6B shows the corrected image data generated by the corrected image data generation unit 6151. FIG. 6C shows the difference image data generated by the difference image data generation unit 6152. 6 shows each image based on the inspection image data, the corrected image data, and the difference image data. In FIG. 6, the lower diagram shows pixel values for each pixel on the predetermined horizontal line HL in the upper diagram. That is, the horizontal axis indicates the pixel position, and the vertical axis indicates the pixel value.

First, the corrected image data generating unit 6151 reads the background image data stored in the memory 62, based on each pixel value X ₁ for each pixel in the background image data _{(m, n),} each pixel value X _{1 (m calculates} the average value X _1a of _n), and the standard deviation S ₁ of each pixel value X _{1 (m, n).} The correction image data generation unit 6151 reads the test image data stored in the memory 62, based on each pixel value X ₂ for each pixel in the inspection image data _{(m, n),} each pixel value X _{2 (m calculates} the average value X _2a of _n), and the standard deviation S ₂ of each pixel value X _{2 (m, n).} Then, the corrected image data generation unit 6151 has a level of each pixel value X _{1 (m, n)} for each pixel in the background image data (an average value of each pixel value X _{1 (m, n)} , a shading curve, each pixel value) X _{1 (m, n)} variation) using the following equation (3), the level of each pixel value X _{2 (m, n)} for each pixel in the inspection image data ₍ each pixel value X _{2 (m, n , The} corrected image data is generated by approximating the average value of _n) , the shading curve, and the variation of each pixel value X2 _{(m, n)} (process ST61: corrected image data generation procedure). Then, the corrected image data generation unit 6151 stores the generated corrected image data in the memory 62. In the following formula (3), X ^′ _{(m, n)} is each pixel value for each pixel of the corrected image data.

  Then, the corrected image data generation procedure ST61 converts the background image data from the state shown in FIG. 4B to the state shown in FIG. 6B, and for each pixel in the inspection image data shown in FIG. 6A. It approximates to the level of each pixel value (average value of each pixel value, shading curve, variation of each pixel value).

After the process ST61, the difference image data generation unit 6152 reads the corrected image data and the inspection image data stored in the memory 62, and each pixel value of the corrected image data from each pixel value of the inspection image data for each corresponding pixel. And difference image data is generated (process ST62: difference image data generation procedure). Then, the difference image data generation unit 6152 stores the generated difference image data in the memory 62.
Then, the difference image data generation procedure ST62 generates difference image data from which shading is removed, as shown in FIG. 6C.

After the process ST6, the defect detection unit 616 of the control unit 61 reads the difference image data stored in the memory 62, performs a general defect enhancement process for enhancing the display defect component based on the difference image data, A pixel position that is a display defect such as a voltage factor defect is specified (process ST7: defect detection step).
For example, the defect detection unit 616 adds a pixel value of each pixel positioned in the horizontal direction and the vertical direction with respect to the pixel of interest for each pixel in the difference image data using a predetermined filter. And the defect detection part 616 specifies the pixel position which is a display defect component by comparing each integrated value integrated | accumulated for every pixel with the preset threshold value.
Then, in the defect detection step ST7, for example, as shown in FIG. 6C, the pixel position P corresponding to the voltage factor defect is specified.

The first embodiment described above has the following effects.
In the present embodiment, since the same liquid crystal panel 10 to be inspected is used in the background image display step ST2, the background image data acquisition step ST3, the inspection image display step ST4, and the inspection image data acquisition step ST5, the background image The installation position of the liquid crystal panel 10 does not shift when data and inspection image data are acquired. Therefore, in the shading correction step ST6, a difference can be obtained between the corresponding pixels of the inspection image data and the background image data, and difference image data in which shading is appropriately removed from the inspection image data can be generated. Therefore, in the defect detection step ST7, the display defect of the liquid crystal panel 10 can be accurately detected based on the difference image data.

In addition, since the liquid crystal panel 10 is driven with the background voltage value in the background image display step ST2 and the liquid crystal panel 10 is driven with the inspection voltage value in the inspection image display step ST4, there is a voltage factor defect in the liquid crystal panel 10. In this case, the voltage factor defect component included in the inspection image data remains in the difference image data even if the inspection image data and the background image data are differentiated between corresponding pixels by the shading correction step ST6. . Therefore, in the defect detection step ST7, display defects of the liquid crystal panel 10, in particular, voltage factor defects can be accurately detected based on the difference image data.
Here, in the inspection image display step ST4, since the liquid crystal panel 10 is driven with the inspection voltage value and the incident light beam is transmitted with a transmittance of 50%, the surrounding pixel positions are included in the inspection image data. It is possible to include both a voltage factor defect component having a lower pixel value and a voltage factor defect component having a pixel value higher than the surrounding pixel position, and by taking the difference between the inspection image data and the background image data, Both of the voltage factor defects can be accurately detected.

By the way, when the background light data acquisition step ST3 and the inspection image data acquisition step ST5 are performed so that the light reception times of the incident light beams to the CCD in the CCD camera 4 are the same, FIG. 4 (A) and FIG. As shown in A), the average values of the pixel values of all the pixels of the acquired background image data and inspection image data are different. For this reason, when the difference between the average values is large, it is difficult to generate the difference image data in which the shading is appropriately removed from the inspection image data in the shading correction step ST6, that is, the difference image data is converted into the difference image data in the defect detection step ST7. Therefore, it is difficult to accurately detect display defects of the liquid crystal panel 10.
In the present embodiment, the background image data acquisition step ST3 and the inspection image data acquisition step ST5 are performed such that the light reception times of the incident light beams to the CCD in the CCD camera 4 are different. As a result, as shown in FIGS. 4B and 5B, the average values of the pixel values of all the pixels of the acquired inspection image data and background image data can be made substantially the same. For this reason, difference image data in which shading is appropriately removed from the inspection image data can be generated in the shading correction step ST6. That is, even if the display defect is minute, the liquid crystal panel based on the difference image data in the defect detection step ST7. Ten display defects can be accurately detected.

By the way, the background image data acquisition step ST3 and the inspection image data acquisition step ST5 are performed such that the light receiving time of the incident light beam to the CCD in the CCD camera 4 is different, so that all the pixels of the background image data and the inspection image data are obtained. Each average value can be combined. However, it is difficult to match the shading curve and pixel value variations between the background image data and the inspection image data. For this reason, when the shading curve, pixel value variation, and the like differ greatly between the background image data and the background image data, it is possible to generate difference image data in which shading is appropriately removed from the inspection image data in the shading correction step ST6. It is difficult, that is, it is difficult to accurately detect the display defect of the liquid crystal panel 10 based on the difference image data in the defect detection step ST7.
In the present embodiment, since the correction image data generation procedure ST61 is performed in the shading correction step ST6, the level of each pixel value for each pixel in the background image data (average value of each pixel value, shading curve, variation in each pixel value) Etc.) can be approximated to the level of each pixel value for each pixel in the inspection image data (average value of each pixel value, shading curve, variation in each pixel value, etc.) to generate corrected image data. Then, in the difference image data generation procedure ST62, difference image data in which shading is appropriately removed from the inspection image data can be generated by taking the difference between the corrected image data and the inspection image data for each corresponding pixel. That is, even if the display defect is minute, the display defect of the liquid crystal panel 10 can be accurately detected based on the difference image data in the defect detection step ST7.

Here, in the corrected image data generation procedure ST61, the background image data is converted into corrected image data using the equation (3) set with the conversion rate S ₂ / S ₁ based on the standard deviation. As a result, in the difference image data generated by the difference image data generation procedure ST62, as shown in FIG. 6C, variations in pixel values in the entire difference image can be reduced. Therefore, in the defect detection step ST7, the display defect detection accuracy in the image center area CA (FIG. 6C) in the liquid crystal panel 10 can be particularly improved based on the difference image data.

[Second Embodiment]
Next, 2nd Embodiment of this invention is described based on drawing.
In the following description, the same structure and the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted or simplified.
This embodiment is different from the first embodiment only in the approximate expression used by the shading correction unit 615 (corrected image data generation unit 6151) when generating corrected image data. Other configurations are the same as those in the first embodiment.

Specifically, the corrected image data generating unit 6151, an average of the background image data (corrected image data) each pixel value X ₁ for each pixel in the _{(m, n)} level (pixel values X _{1 (m, n)} Value, shading curve, and variation of each pixel value X _{1 (m, n)} ) using the following equation (4), each pixel value X _{2 (for} each pixel in the inspection image data (non-correction target image data)) _{m, n)} level (average value of each pixel value X2 _{(m, n)} , shading curve, variation of each pixel value X2 _{(m, n)} ) is approximated to generate corrected image data.

The second embodiment described above has the following effects in addition to the same effects as those of the first embodiment.
FIG. 7 is a diagram for explaining the effect of the second embodiment. Specifically, FIG. 7 has a configuration similar to that of FIG.
In the present embodiment, in the corrected image data generation procedure ST61, the background image data is converted into corrected image data using the equation (4) set by the conversion rate S ₂ ² / S ₁ ² by dispersion. As a result, in the difference image data generated by the difference image data generation procedure ST62, as shown in FIG. 7C, the average value of each pixel value in the entire difference image and the pixel value in the image peripheral area EA And the difference can be made small. For this reason, in the defect detection step ST7, the display defect detection accuracy in the image peripheral area EA in the liquid crystal panel 10 can be particularly improved based on the difference image data.

[Third embodiment]
Next, 3rd Embodiment of this invention is described based on drawing.
In the following description, the same structure and the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted or simplified.
FIG. 8 is a block diagram illustrating a schematic configuration of the control device 6A according to the third embodiment.
This embodiment is different from the first embodiment only in the configuration of the control device 6A as shown in FIG. Other configurations are the same as those in the first embodiment.

As shown in FIG. 8, the control device 6A includes a control unit 61A in addition to the memory 62 described in the first embodiment.
As shown in FIG. 8, the control unit 61A includes an inspection image display control unit 611, a background image display control unit 612, an inspection image data acquisition unit 613, a background image data acquisition unit 614, and a defect described in the first embodiment. In addition to the detection unit 616, a shading correction unit 615A, an outermost periphery image display control unit 617, an outermost periphery image data acquisition unit 618, and an inspection target region determination unit 619 are provided.

  The outermost peripheral image display control unit 617 reads the outermost peripheral pixel information regarding the outermost peripheral pixel of the liquid crystal panel 10 stored in the memory 62, the outermost peripheral pixel of the liquid crystal panel 10 has a predetermined luminance value, and the other pixels are A predetermined control signal for driving the liquid crystal panel 10 to output a luminance value smaller than the predetermined luminance value is output to the panel control device 5. Then, the panel control device 5 drives the liquid crystal panel 10 according to the control signal output from the outermost periphery image display control unit 617, and causes the liquid crystal panel 10 to form the outermost periphery image. In the present embodiment, the outermost periphery image display control unit 617 displays the liquid crystal so that the outermost peripheral pixel of the liquid crystal panel 10 has the maximum luminance value (white display) and the other pixels have the minimum luminance value (black display). The panel 10 is driven and controlled.

  The outermost periphery image data acquisition unit 618 outputs a predetermined control signal to the CCD camera 4 when the outermost periphery image is formed on the liquid crystal panel 10 and outputs the projection surface (outermost periphery image) to the CCD camera 4. Image). Further, the outermost periphery image data acquisition unit 618 receives an electrical signal output from the CCD camera 4 and converts it into a computer-readable signal (digital signal), and relates to a pixel value (luminance value) for each pixel. The outermost periphery image data including information is acquired. Then, the outermost periphery image data acquisition unit 618 stores the acquired outermost periphery image data in the memory 62.

  The inspection target area determination unit 619 reads the outermost peripheral image data stored in the memory 62, and recognizes the outer edge position (the coordinate value of the pixel position) corresponding to the outermost peripheral pixel of the liquid crystal panel 10 based on the outermost peripheral image data. The inside of the outer edge position is determined as the inspection target area. Then, the inspection target area determination unit 619 causes the memory 62 to store inspection target area information regarding the determined inspection target area.

As shown in FIG. 8, the shading correction unit 615A includes an inspection target region extraction unit 6153 in addition to the correction image data generation unit 6151 and the difference image data generation unit 6152 described in the first embodiment.
The inspection target area extraction unit 6153 reads the inspection target area information, background image data, and inspection image data stored in the memory 62, and extracts the background extraction image data (correction target extraction image data) from which the inspection target area of the background image data is extracted. ) And inspection extracted image data (uncorrected target extracted image data) obtained by extracting the inspection target region of the inspection image data. Then, the inspection target area extraction unit 6153 stores the generated background extraction image data and inspection extraction image data in the memory 62.
Here, in this embodiment, unlike the first embodiment, the corrected image data generation unit 6151 generates corrected image data based on the background extracted image data and the inspection extracted image data stored in the memory 62. . Further, unlike the first embodiment, the difference image data generation unit 6152 generates difference image data based on the corrected image data and the inspection extraction image data stored in the memory 62.
In the present embodiment, the memory 62 is processed by a predetermined control program, information for executing processing by the control unit 61A (voltage value information, speed information, outermost peripheral pixel information), and the control unit 61A. Store the data.

Next, the defect detection method in 3rd Embodiment is demonstrated based on drawing.
FIG. 9 is a flowchart for explaining a defect detection method according to the third embodiment.
In the following, processing similar to the defect detection method in the first embodiment will be described in a simplified manner.
That is, similarly to the first embodiment, the control unit 61A turns on the light source device 21 (process ST1), displays a background image (process ST2), and acquires background image data (process ST3).
FIG. 10 is a diagram illustrating an outermost peripheral image projected and displayed on the screen 3.
After the process ST2, the outermost periphery image display control unit 617 of the control unit 61A reads out the outermost periphery pixel information stored in the memory 62, and gives a control signal for displaying the outermost periphery image on the liquid crystal panel 10 to the panel control device 5. Output to. Then, the liquid crystal panel 10 forms an outermost peripheral image with the outermost peripheral pixel as the maximum luminance value and the other pixels as the minimum pixel value, and the outermost peripheral image is projected and displayed on the screen 3 as shown in FIG. ST8: outermost periphery image display step).

  After the process ST8, the outermost periphery image data acquisition unit 618 of the control unit 61A outputs a predetermined control signal to the CCD camera 4 to cause the CCD camera 4 to capture the projection surface (including the outermost periphery image) of the screen 3. Peripheral image data is acquired (process ST9: outermost peripheral image data acquisition step). Then, the outermost periphery image data acquisition unit 618 stores the acquired outermost periphery image data in the memory 62.

After the process ST8, the control unit 61A performs the display of the inspection image (process ST4) and the acquisition of the inspection image data (process ST5) as in the first embodiment.
After the process ST5, the inspection target area determination unit 619 of the control unit 61A reads the outermost peripheral image data stored in the memory 62, and the outer edge position (corresponding to the outermost peripheral pixel of the liquid crystal panel 10 based on the outermost peripheral image data). The coordinate value of the pixel position) is recognized, and the inside of the outer edge position is determined as the inspection target region (processing ST10: inspection target region determination step). Then, the inspection target area determination unit 619 causes the memory 62 to store inspection target area information regarding the determined inspection target area.
For example, on the screen 3, as shown in FIG. 10, the position corresponding to the outermost peripheral pixel of the liquid crystal panel 10 is bright, and other areas, that is, the projection surface of the screen 3, other than the outermost peripheral pixel of the liquid crystal panel 10. The position corresponding to the pixel is dark. For this reason, as shown in FIG. 10, the inspection target region determination unit 619 determines the pixel position at which the pixel value is equal to or greater than a predetermined threshold based on each pixel value for each pixel in the outermost peripheral image data. The outer edge position E (the coordinate value of the pixel position) corresponding to the peripheral pixel is determined, and the inside of the outer edge position E (the area excluding the projection surface of the screen 3) is determined as the inspection target area.

After processing ST10, the shading correction unit 615A of the control unit 61A performs shading correction as described below (processing ST6A: shading correction step).
First, the inspection target area extraction unit 6153 reads the inspection target area information, background image data, and inspection image data stored in the memory 62, and generates background extracted image data in which the inspection target area of the background image data is extracted. Then, the inspection extraction image data obtained by extracting the inspection target area of the inspection image data is generated (process ST63: inspection target area extraction procedure). Then, the inspection target area extraction unit 6153 stores the generated background extraction image data and inspection extraction image data in the memory 62.
Here, in the processes ST1 to ST10 described above, the liquid crystal panel 10 to be inspected is the same, and the installation position of the liquid crystal panel 10 is not changed. For this reason, the background extracted image data generated by the process ST63 is image data having only the background image excluding the projection surface of the screen 3. Similarly, the inspection extracted image data generated by the process ST63 is image data having only the inspection image excluding the projection surface of the screen 3.

After the process ST63, the corrected image data generation unit 6151 reads the background extracted image data stored in the memory 62, and based on each pixel value X1 _{(m, n)} for each pixel in the background extracted image data, calculating the standard deviation S ₁ value X _{1 (m, n)} the average value X _1a, and each pixel value X _{1 (m, n).} The correction image data generation unit 6151 reads the test extracts image data stored in the memory 62, based on each pixel value X ₂ for each pixel _{(m, n)} in the inspection extracted image data, each pixel value X ₂ calculated _{(m, n)} the average value X _2a, and the standard deviation S ₂ of each pixel value X _{2 (m, n).} The corrected image data generation unit 6151 then outputs the level of each pixel value X _{1 (m, n)} for each pixel in the background extracted image data (the average value of each pixel value X _{1 (m, n)} , the shading curve, each pixel ₍ Variation of the value X _{1 (m, n)} ) using the above equation (3), the level of each pixel value X _{2 (m, n)} for each pixel in the inspection extraction image data (each pixel value X _{2 (m , n)} average value, shading curve, variation of each pixel value X _{2 (m, n))} to generate corrected image data (process ST61A: corrected image data generation procedure). Then, the corrected image data generation unit 6151 stores the generated corrected image data in the memory 62.

After the process ST61A, the difference image data generation unit 6152 reads out the corrected image data and the inspection extraction image data stored in the memory 62, and for each corresponding pixel, each of the correction image data is calculated from each pixel value of the inspection extraction image data. The difference between pixel values is taken to generate difference image data (process ST62A: difference image data generation procedure).
After the process ST6A, the control unit 61 identifies a pixel position that is a display defect (process ST7), as in the first embodiment.

The third embodiment described above has the following effects in addition to the same effects as those of the first embodiment.
By the way, when a background image or an inspection image displayed on the liquid crystal panel 10 is captured by the CCD camera 4, only an inspection target area (all areas on which the inspection image and the background image are displayed) on the liquid crystal panel 10 is captured. Instead, for example, the projection surface of the screen 3 other than the inspection target region is also imaged. In other words, the inspection image data and the background image data are image data including portions other than the inspection target region in addition to the inspection target region. Therefore, in the first embodiment, when generating the corrected image data, the background image data is converted into the corrected image data by the equation (3) based on the average value and the standard deviation including the pixel values of the portions other than the inspection target region. Therefore, it is difficult to match the average value of each pixel value of all the pixels, the shading curve, and variations in pixel values between the inspection image data and the background image data. For this reason, it is difficult to generate the difference image data in which the shading is appropriately removed from the inspection image data in the difference image data generation procedure ST62, that is, the display defect of the liquid crystal panel 10 is detected based on the difference image data in the defect detection step ST7. It is difficult to detect accurately.

  In this embodiment, the outer edge position E corresponding to the outermost peripheral pixel of the liquid crystal panel 10 in the background image data and the inspection image data is determined by the outermost peripheral image display step ST8, the outermost peripheral image data acquisition step ST9, and the inspection target region determination step ST10. The inspection target area is extracted in the inspection target area extraction procedure ST63 to generate background extracted image data, and the inspection target area of the inspection image data is extracted to generate inspection extracted image data. Thus, in the corrected image data generation procedure ST61A, the corrected image data is generated based on the background extracted image data and the inspection extracted image data, thereby obtaining an average value or standard deviation including only each pixel value of the inspection target region. The corrected image data converted by the formula (3) based thereon can be generated. For this reason, it is possible to satisfactorily match the average value of all the pixels, the shading curve, the variation in pixel values, and the like between the inspection image data and the background image data. Therefore, by calculating the difference between the corrected image data and the inspection extracted image data in the difference image data generation procedure ST62A, it is possible to generate difference image data in which shading is appropriately removed from the inspection image data. The display defect of the liquid crystal panel 10 can be detected with high accuracy based on the image data.

[Fourth embodiment]
Next, 4th Embodiment of this invention is described based on drawing.
In the following description, the same structure and the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted or simplified.
In the first embodiment, the control device 6 displays only one background image and detects a display defect of the liquid crystal panel 10 using one background image data.
On the other hand, in 2nd Embodiment, the control apparatus 6 displays two different background images, and detects the display defect of the liquid crystal panel 10 using two background image data. That is, this embodiment is different from the first embodiment only in the processing function in the control device 6.

Specifically, processing functions different from those of the first embodiment in the control device 6 are as follows.
The background image display control unit 612 reads voltage value information related to the voltage value applied to the liquid crystal panel 10 stored in the memory 62, and drives the liquid crystal panel 10 with the first background voltage value based on the voltage value information. A predetermined control signal is output to the panel control device 5. The panel control device 5 drives the liquid crystal panel 10 with the first background voltage value in accordance with the control signal output from the background image display control unit 612, and causes the liquid crystal panel 10 to form the first background image. .
The first background voltage value is the same voltage value (first background voltage value) applied to all the pixels of the liquid crystal panel 10 when there is a voltage factor defect in the liquid crystal panel 10. In this case, the gradation value of the pixel position corresponding to the voltage factor defect in the liquid crystal panel 10 is substantially the same as the gradation value of the surrounding pixel positions, and the pixel position corresponding to the voltage factor defect cannot be detected (voltage factor). This is a voltage value that makes it impossible to discriminate between a pixel position corresponding to a defect and surrounding pixel positions, and is stored in advance in the memory 62 as voltage value information. In the present embodiment, the first background voltage value is set to 0 V, which is a voltage value lower than the inspection voltage value. That is, in the present embodiment, the background image display control unit 612 outputs a control signal to the panel control device 5 to cause the liquid crystal panel 10 to perform black display as the first background image.

Further, the background image display control unit 612 reads voltage value information related to the voltage value applied to the liquid crystal panel 10 stored in the memory 62, and drives the liquid crystal panel 10 with the second background voltage value based on the voltage value information. A predetermined control signal is output to the panel control device 5. The panel control device 5 drives the liquid crystal panel 10 with the second background voltage value according to the control signal output from the background image display control unit 612, and causes the liquid crystal panel 10 to form the second background image. .
The second background voltage value is a voltage value higher than the inspection voltage value, and is stored in advance in the memory 62 as voltage value information. In the present embodiment, the second background voltage value is a voltage value that causes the liquid crystal panel 10 to drive so as to transmit a light beam with a transmittance of 100% to form a second background image (white image). Is set to That is, in the present embodiment, the background image display control unit 612 outputs a control signal to the panel control device 5 to cause the liquid crystal panel 10 to perform white display as the second background image.

  The background image data acquisition unit 614 outputs a predetermined control signal to the CCD camera 4 and outputs the screen 3 to the CCD camera 4 when the first background image or the second background image is formed on the liquid crystal panel 10. The projection surface (including the first background image or the second background image) is captured. The background image data acquisition unit 613 receives the electrical signal output from the CCD camera 4 and converts it into a signal that can be read by a computer. The background image data acquisition unit 613 includes first information including pixel value (luminance value) information for each pixel. First background image data based on the second background image and second background image data based on the second background image are respectively acquired. Then, the background image data acquisition unit 614 stores the acquired background image data in the memory 62.

The inspection image data acquisition unit 613 and the background image data acquisition unit 614 drive and control the shutter in the CCD camera 4 in the same manner as in the first embodiment when acquiring the inspection image data and each background image data.
That is, the inspection image data acquisition unit 613 and the background image data acquisition unit 614 read speed information regarding the moving speed of the shutter (shutter speed) in the CCD camera 4 stored in the memory 62, and when the inspection image is captured by the CCD camera 4. The shutter is driven and controlled so that the light reception time of the incident light beam by the CCD differs between when the first background image is captured and when the second background image is captured. In the present embodiment, the shutter speed at the time of capturing the first background image is set slower than the shutter speed at the time of capturing the inspection image, and the shutter speed at the time of capturing the second background image is set to be low. It is set fast. Then, by the shutter drive control in the CCD camera 4 by the inspection image data acquisition unit 613 and the background image data acquisition unit 614, all the pixels in the acquired inspection image data, the first background image data, and the second background image data are detected. Each average value of the pixel values is the same.

The corrected image data generation unit 6151 constituting the shading correction unit 615 reads the first background image data (correction target image data) and inspection image data (non-correction target image data) stored in the memory 62, and performs the first implementation. Similarly to the form, the level of each pixel value (average value of each pixel value, shading curve, variation in each pixel value) for each pixel in the first background image data is determined as the value of each pixel value for each pixel in the inspection image data. First corrected image data is generated by approximating the level.
The corrected image data generation unit 6151 reads the second background image data (correction target image data) and the inspection image data (non-correction target image data) stored in the memory 62, and similarly to the second background, Second correction image data is generated by approximating the level of each pixel value for each pixel in the image data to the level of each pixel value for each pixel in the inspection image data.
Then, the corrected image data generation unit 6151 stores the generated corrected image data in the memory 62.

The difference image data generation unit 6152 constituting the shading correction unit 615 takes the first correction image data and the inspection image data stored in the memory 62 for each corresponding pixel value, and calculates the first difference image. Generate data.
In addition, the difference image data generation unit 6152 takes the difference between the pixel values for each pixel corresponding to the second corrected image data and the inspection image data stored in the memory 62, and generates second difference image data.
Then, the difference image data generation unit 6152 stores the generated difference image data in the memory 62.
The defect detection unit 616 reads each difference image data stored in the memory 62, performs defect enhancement processing based on each difference image data, and performs pixel enhancement corresponding to the display defect, as in the first embodiment. Is identified.

Next, the defect detection method in 4th Embodiment is demonstrated based on drawing.
FIG. 11 is a flowchart for explaining a defect detection method according to the fourth embodiment.
In the following, processing similar to the defect detection method in the first embodiment will be described in a simplified manner.
That is, the control unit 61 turns on the light source device 21 (process ST1), as in the first embodiment.
After the process ST1, the background image display control unit 612 of the control unit 61 uses the voltage value information (first background voltage value) stored in the memory 62, as in the process ST2 described in the first embodiment. Reading and outputting to the panel control device 5 a control signal for effecting black display on the liquid crystal panel 10. Then, the liquid crystal panel 10 blocks the incident light beam to form a black image (first background image), and the first background image is projected and displayed on the screen 3 (processing ST2B1: first background image display step). .
After the process ST2B1, the background image data acquisition unit 614 of the control unit 61 outputs a predetermined control signal to the CCD camera 4 and outputs the screen 3 to the CCD camera 4 in the same manner as the process ST3 described in the first embodiment. The projection surface (including the first background image) is imaged to acquire first background image data (processing ST3B1: background image data acquisition step). Then, the background image data acquisition unit 614 stores the acquired first background image data in the memory 62.

After the process ST3B1, the background image display control unit 612 reads the voltage value information (second background voltage value) stored in the memory 62, and performs a panel control on a control signal for performing white display on the liquid crystal panel 10. Output to the device 5. Then, the liquid crystal panel 10 transmits the incident light flux to form a white image (second background image), and the second background image is projected and displayed on the screen 3 (processing ST2B2: second background image display step). .
After the process ST3B1, the background image data acquisition unit 614 acquires the second background image data by causing the CCD camera 4 to capture the projection surface (including the second background image) of the screen 3 in the same manner as the process ST3B1. Process ST3B2: Background image data acquisition step). Then, the background image data acquisition unit 614 stores the acquired second background image data in the memory 62.

After the process ST3B2, the control unit 61 displays the inspection image (process ST4) and acquires the inspection image data (process ST5), as in the first embodiment.
Although specific illustration is omitted, the background image data and the inspection image data acquired in the processes ST3B1, ST3B2, and ST5 are obtained by the background image data acquisition unit 614 and the inspection image data acquisition unit 613 as described above. Due to the shutter drive control in the CCD camera 4, the average values of the pixel values of all the pixels are substantially the same.

After process ST5, the shading correction unit 615 of the control unit 61 performs shading correction as described below (process ST6B: shading correction step).
12 and 13 are diagrams for explaining the shading correction step ST6B. Specifically, FIG. 12 and FIG. 13 have the same configuration as that of FIG. 6 and FIG. FIG. 12 is a diagram showing shading correction using the first background image data. FIG. 13 is a diagram showing shading correction using the second background image data.
First, the corrected image data generation unit 6151 reads the first background image data stored in the memory 62, and based on each pixel value X1 _{(m, n)} for each pixel in the first background image data, pixel values X _{1 (m, n)} is calculated the average value X _1a, and the standard deviation S ₁ of each pixel value X _{1 (m, n).} The correction image data generation unit 6151 reads the test image data stored in the memory 62, based on each pixel value X ₂ for each pixel in the inspection image data _{(m, n),} each pixel value X _{2 (m calculates} the average value X _2a of _n), and the standard deviation S ₂ of each pixel value X _{2 (m, n).} Then, the corrected image data generation unit 6151 has a level of each pixel value X _{1 (m, n)} for each pixel in the first background image data (an average value of each pixel value X _{1 (m, n)} , a shading curve, The variation of each pixel value X _{1 (m, n)} ) is calculated using the above equation (3), and the level of each pixel value X _{2 (m, n)} for each pixel in the inspection image data (each pixel value X _{2 (} The first corrected image data is generated by approximating the average value of _{m, n)} , the shading curve, and the variation of each pixel value X2 _{(m, n)} (process ST61B1: corrected image data generation procedure). Then, the corrected image data generation unit 6151 stores the generated first corrected image data in the memory 62.

After the process ST61B1, the corrected image data generation unit 6151 reads the second background image data stored in the memory 62, and based on each pixel value X1 _{(m, n)} for each pixel in the second background image data. Te to calculate the standard deviation S ₁ of the average value X _1a, and each pixel value X ₁ of the pixel values _{X 1 (m, n) (} m, n). Then, the corrected image data generation unit 6151 has a level of each pixel value X _{1 (m, n)} for each pixel in the second background image data (an average value of each pixel value X _{1 (m, n)} , a shading curve, The variation of each pixel value X _{1 (m, n)} ) is calculated using the above equation (3), and the level of each pixel value X _{2 (m, n)} for each pixel in the inspection image data (each pixel value X _{2 (} The second corrected image data is generated by approximating the average value of _{m, n)} , the shading curve, and the variation of each pixel value X2 _{(m, n)} (process ST61B2: corrected image data generation procedure). Then, the corrected image data generation unit 6151 stores the generated second corrected image data in the memory 62.

  After process ST61B2, the difference image data generation unit 6152 reads the first corrected image data and the inspection image data stored in the memory 62, and performs first correction from each pixel value of the inspection image data for each corresponding pixel. The difference of each pixel value of image data is taken and 1st difference image data is produced | generated (process ST62B1: difference image data production | generation procedure).

  Here, in the process ST4, the inspection image display control unit 611 drives the liquid crystal panel 10 with the inspection voltage value. Therefore, when there is a voltage factor defect in the liquid crystal panel 10, FIG. As shown in FIG. 13A, a voltage factor defect component is generated at the pixel position P1, and it becomes possible to distinguish from surrounding components. Further, since a gray image having an intermediate gradation value is displayed on the liquid crystal panel 10, white defects (defects caused by missing pixels, etc.) appear on the liquid crystal panel 10 so that all pixels have the same luminance value. When the liquid crystal panel 10 is driven, if there is a defect in the pixel position where the luminance value is higher than that of the surrounding pixels, as shown in FIGS. 12A and 13A, the pixel position P2 is displayed. A white defect component is generated, and it becomes possible to distinguish from surrounding components. Similarly, a pixel position where the liquid crystal panel 10 has a black defect (a defect caused by a foreign substance or the like, and the luminance value is lower than the surrounding pixels when the liquid crystal panel 10 is driven so that all pixels have the same luminance value. Even when there is a defect), a black defect component is generated at the pixel position P3, as shown in FIGS. 12A and 13A, so that it can be distinguished from surrounding components.

  On the other hand, in the process ST2B1, since the background image display control unit 612 drives the liquid crystal panel 10 with the first background voltage value (0 V), the voltage factor defect exists in the liquid crystal panel 10. However, as shown in FIG. 12B, the voltage factor defect component and surrounding components cannot be distinguished (the pixel value at the pixel position corresponding to the voltage factor defect and the pixel at the surrounding pixel position). Value is almost the same). Further, since the background image display control unit 612 displays the black image (first background image) having the minimum luminance value on the liquid crystal panel 10, the black image is present in the liquid crystal panel 10. However, as shown in FIG. 12B, the black defect component and the surrounding component cannot be distinguished (the pixel value of the pixel position corresponding to the black defect and the pixel value of the surrounding pixel position are Almost identical). On the other hand, when there is a white defect in the liquid crystal panel 10, as shown in FIG. 12B, a white defect component is generated at the pixel position P2, and it becomes possible to distinguish from surrounding components.

  Therefore, when the difference between the pixel values of the first background image data (first corrected image data) is taken for each corresponding pixel from the pixel values of the inspection image data as described above in the process ST62B1, In the first difference image data, as shown in FIG. 12C, the white defect component at the pixel position P2 is removed, and the voltage factor defect component at the pixel position P1 and the black defect component at the pixel position P3 remain. Become.

  After the process ST62B1, the difference image data generation unit 6152 reads the second corrected image data and the inspection image data stored in the memory 62, and performs the second correction from each pixel value of the inspection image data for each corresponding pixel. The difference of each pixel value of image data is taken and 2nd difference image data is produced | generated (process ST62B2: difference image data production | generation procedure).

  Here, in the process ST2B2, the background image display control unit 612 displays the white image (second background image) having the maximum luminance value on the liquid crystal panel 10, so that the voltage factor defect (this embodiment) is displayed on the liquid crystal panel 10. In the embodiment, even when the luminance value is higher than that of the surrounding pixels), it is impossible to distinguish the voltage factor defect component and the surrounding component as shown in FIG. (The pixel value at the pixel position corresponding to the voltage factor defect and the pixel values at the surrounding pixel positions are substantially the same). Similarly, even when a white defect exists in the liquid crystal panel 10, as shown in FIG. 13B, the white defect component and surrounding components cannot be distinguished (white defect). The pixel value at the pixel position corresponding to and the pixel values at the surrounding pixel positions are substantially the same). On the other hand, when the black defect is present in the liquid crystal panel 10, as shown in FIG. 13B, a black defect component is generated at the pixel position P3, and it becomes possible to distinguish from the surrounding components. .

  Therefore, in process ST62B2, when the difference between the pixel values of the second background image data (second corrected image data) from the pixel values of the inspection image data as described above is taken for each corresponding pixel, In the second difference image data, as shown in FIG. 13C, the black defect component at the pixel position P3 is removed, and the voltage factor defect component at the pixel position P1 and the white defect component at the pixel position P2 remain. Become.

After the process ST6B, the defect detection unit 616 of the control unit 61 reads each difference image data stored in the memory 62, and based on each difference image data, similarly to the process ST7 described in the first embodiment, Defect emphasis processing is performed to identify the pixel position that is a display defect (processing ST7B: defect detection step).
Then, in the defect detection step ST7B, as shown in FIG. 12C, the pixel position P1 corresponding to the voltage factor defect and the pixel position P3 corresponding to the black defect are specified based on the first difference image data. The Further, as shown in FIG. 13C, the pixel position P1 corresponding to the voltage factor defect and the pixel position P2 corresponding to the white defect are specified based on the second difference image data.

The fourth embodiment described above has the following effects in addition to the same effects as those of the first embodiment.
In this embodiment, since two different background images are displayed and the display defect of the liquid crystal panel 10 is detected using the two background image data, the first difference image data and the second difference image data are displayed. Based on this, it is possible to accurately detect not only the voltage factor defect of the liquid crystal panel 10 but also almost all display defects including white defects and black defects.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In each of the embodiments described above, the inspection voltage value is a voltage value that drives the liquid crystal panel 10 to transmit a light beam with a transmittance of 50% to form an inspection image of a gray image having an intermediate gradation value. However, this is not a limitation. As a voltage value for inspection, when a voltage factor defect exists in the liquid crystal panel 10, the same voltage value (voltage value for inspection) is applied to all the pixels of the liquid crystal panel 10. Any voltage value may be used as long as the gradation value at the pixel position corresponding to the voltage factor defect is different from the gradation values at the other pixel positions and enables detection of the pixel position corresponding to the voltage factor defect. .

In each of the above embodiments, the background voltage value (first background voltage value) is set to 0 V, but the present invention is not limited to this. As a background voltage value, when a voltage factor defect exists in the liquid crystal panel 10, the same voltage value (background voltage value) is applied to all the pixels of the liquid crystal panel 10. Any voltage value can be used as long as the gradation value at the pixel position corresponding to the voltage factor defect is substantially the same as the gradation value at the other pixel positions and the pixel position corresponding to the voltage factor defect cannot be detected. It doesn't matter.
Similarly, in the fourth embodiment, the second background voltage value is a voltage value that drives the liquid crystal panel 10 to transmit a light beam with a transmittance of 100% to form an inspection image of a white image. However, it is not limited to this. The second background voltage value is a voltage value different from the inspection voltage value, and is lower than the inspection voltage value when the first background voltage value is lower than the inspection voltage value. Any voltage value may be used as long as it is a high voltage value and the first background voltage value is a voltage value higher than the inspection voltage value as long as the voltage value is lower than the inspection voltage value.

In each of the above-described embodiments, the background image data acquisition step ST3 (ST3B1, ST3B2) and the inspection image data acquisition step ST5 are performed such that the shutter of the CCD camera 4 is driven and controlled so that the light reception time of the incident light beam on the CCD is different. However, it is not limited to this. For example, in the background image data acquisition step ST3 (ST3B1, ST3B2) and the inspection image data acquisition step ST5, the light reception time of the incident light beam to the CCD in the CCD camera 4 is made the same, that is, the shutter speed is set to the normal shutter speed. The light source device 21 is driven and controlled so that the average values of the pixel values of all the pixels in the inspection image data and the background image data are substantially the same, that is, the amount of light emitted from the light source device 21, that is, the liquid crystal You may implement so that the light quantity of the incident light beam to the panel 10 may differ. Further, the average value of the pixel values of all the pixels in the inspection image data and the background image data may be made substantially the same by using the drive control of the shutter in the CCD camera 4 and the drive control of the light source device 21 together. Absent.
In each of the above embodiments, each of the pixel values between the inspection image data and the background image data is obtained by converting the background image data using the equations (3) and (4) in the shading correction steps ST6, ST6A, and ST6B. Since the average values can be matched, the light reception time of the incident light beam to the CCD in the CCD camera 4 in the background image data acquisition step ST3 (ST3B1, ST3B2) and the inspection image data acquisition step ST5 may be the same.

In the third embodiment and the fourth embodiment, the corrected image data is generated using the expression (3) as in the first embodiment. However, the present invention is not limited to this, and the second embodiment is not limited thereto. As described above, the corrected image data may be generated using Expression (4).
In each of the above embodiments, corrected image data is generated using the equation (3) described in the first embodiment, and display defects are detected based on difference image data generated from the corrected image data. A configuration may be adopted in which corrected image data is generated using Expression (4) described in the second embodiment, and display defects are detected based on difference image data generated from the corrected image data. With such a configuration, it is possible to improve the display defect detection accuracy in both the image center area CA and the image peripheral area EA.
In each of the above embodiments, the approximate expression used when generating the corrected image data is not limited to the expressions (3) and (4) described in the above embodiments, and other approximate expressions may be adopted. Absent.

In the first embodiment, the second embodiment, and the fourth embodiment, the correction target image data is background image data and the non-correction target image data is inspection image data. The correction target image data may be inspection image data, and the non-correction target image data may be background image data.
Similarly, in the third embodiment, the correction target extraction image data is the background extraction image data and the non-correction target extraction image data is the inspection extraction image data. However, the present invention is not limited to this. The inspection extraction image data and the non-correction target image data may be the background extraction image data.

  In the first to third embodiments, in the background image display step ST2 and the background image data acquisition step ST3, a background image is formed on the liquid crystal panel 10 and the projection surface (including the background image) of the screen 3 is captured. However, the present invention is not limited to this, and the background image data is obtained by imaging the projection surface of the screen 3 in a state where the liquid crystal panel 10 is not installed in the panel installation unit in the defect detection apparatus 1. You can get it.

In the third embodiment, after the background extraction image data and the inspection extraction image data are generated in the inspection target region extraction procedure ST63, the background extraction image data and the inspection extraction image data are subjected to geometric deformation by image processing. Thus, a configuration in which the image is rectangular by correcting distortion, deformation, or the like of the image may be employed.
In the third embodiment, in the outermost peripheral image display step ST8, the outermost peripheral image is displayed by driving the liquid crystal panel 10 so that the outermost peripheral pixel of the liquid crystal panel 10 has the maximum luminance value and the other pixels have the minimum luminance value. Although formed, it is not restricted to this. If the liquid crystal panel 10 is driven to form the outermost peripheral image so that the outermost peripheral pixel of the liquid crystal panel 10 has a predetermined luminance value and the other pixels have a luminance value smaller than the predetermined luminance value, The luminance value of the pixel or other pixels may be any luminance value.
In the fourth embodiment, as described in the third embodiment, the inspection target regions are extracted from the first background image data, the second background image data, and the inspection image data. The display defect of the liquid crystal panel 10 may be detected based on the data.

  In each of the above embodiments, the flow of the defect detection method (FIGS. 3, 9, and 11) is not limited to the flow described in each of the above embodiments. For example, in each of the above embodiments, the background image display step ST2 (ST2B1, ST2B2) and the background image data acquisition step ST3 (ST3B1, ST3B2) are performed before the inspection image display step ST4 and the inspection image data acquisition step ST5. However, the present invention is not limited to this, and the background image display step ST2 (ST2B1, ST2B2) and the background image data acquisition step ST3 (ST3B1, ST3B2) are performed after the inspection image display step ST4 and the inspection image data acquisition step ST5. It doesn't matter. Further, in the third embodiment, the outermost peripheral image display step ST8 and the outermost peripheral image data acquisition step ST9 are replaced with the background image display step ST2, the background image data acquisition step ST3, the inspection image display step ST4, and the inspection image data acquisition step ST5. However, the present invention is not limited to this, and may be performed before the background image display step ST2 and the background image data acquisition step ST3 or after the inspection image display step ST4 and the inspection image data acquisition step ST5. Absent.

  In each of the above embodiments, the liquid crystal panel 10 using TFT elements is used as the image display device. However, the present invention is not limited to this, and other transmissive liquid crystal panels, reflective liquid crystal panels such as LCOS (Liquid Crystal On Silicon), and the like. An image display device such as a liquid crystal panel, a plasma display, an EL display, or a DMD (digital micromirror device) using the diode element may be employed.

The best configuration for implementing the present invention has been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but it is not intended to depart from the technical concept and scope of the invention. Various modifications can be made by those skilled in the art in terms of materials, quantity, and other detailed configurations.
Therefore, the description limited to the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

The figure which shows the structure of the defect detection apparatus in 1st Embodiment. The block diagram which shows schematic structure of the control apparatus in the said embodiment. The flowchart explaining the defect detection method in the said embodiment. The figure for demonstrating the background image data acquisition step in the said embodiment. The figure for demonstrating the test | inspection image data acquisition step in the said embodiment. The figure for demonstrating the shading correction | amendment step in the said embodiment. The figure for demonstrating the effect of 2nd Embodiment. The block diagram which shows schematic structure of the control apparatus in 3rd Embodiment. The flowchart explaining the defect detection method in the said embodiment. The figure which shows the outermost periphery image projected and displayed on the screen in the said embodiment. The flowchart explaining the defect detection method in 4th Embodiment. The figure for demonstrating the shading correction | amendment step in the said embodiment. The figure for demonstrating the shading correction | amendment step in the said embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Defect detection apparatus, 10 ... Liquid crystal panel (image display device), 21 ... Light source device, 4 ... CCD camera (imaging device), 6, 6A ... Control apparatus, 611 ... Inspection image display control unit, 612 ... Background image display control unit, 613 ... Inspection image data acquisition unit, 614 ... Background image data acquisition unit, 615, 615A ... Shading correction unit, 616 Defect detection unit, ST2 ... background image display step, ST2B1 ... first background image display step, ST2B2 ... second background image display step, ST3, ST3B1, ST3B2 ... background image data acquisition Step, ST4 ... Inspection image display step, ST5 ... Inspection image data acquisition step, ST6, ST6A, ST6B ... Shading correction step, ST , ST7B ... defect detection step, ST8 ... outermost periphery image display step, ST9 ... outermost periphery image data acquisition step, ST10 ... inspection object area determination step, ST61, ST61A, ST61B1, ST61B2 ... Correction image data generation procedure, ST62, ST62A, ST62B1, ST62B2... Difference image data generation procedure, ST63.

Claims (10)

A defect detection method for detecting a display defect of an image display device that displays an image by modulating an incident light beam for each pixel by applying a voltage of a predetermined voltage value,
When the voltage display defect that can be generated in an image when a voltage having a predetermined voltage value is present in the image display device, the image display device is enabled in a state that enables detection of the voltage cause defect. An inspection image display step of driving the image display device with an inspection voltage value for driving and displaying an inspection image on the image display device;
An inspection image data acquisition step of acquiring an inspection image data by causing an imaging device to image the inspection image displayed on the image display device;
Unlike the inspection voltage value, the image display device is driven with a background voltage value for driving the image display device in a state in which detection of the voltage factor defect is impossible, and a background image is displayed on the image display device. A background image display step for displaying
A background image data acquisition step of acquiring a background image data by causing the imaging device to capture a background image displayed on the image display device;
A shading correction step for taking a difference for each corresponding pixel of the inspection image data and the background image data and generating difference image data;
And a defect detection step of detecting a display defect of the image display device based on the difference image data. A defect detection method for detecting a display defect of an image display device that displays an image by modulating an incident light beam for each pixel by applying a voltage of a predetermined voltage value,
When the voltage display defect that can be generated in an image when a voltage having a predetermined voltage value is present in the image display device, the image display device is enabled in a state that enables detection of the voltage cause defect. An inspection image display step of driving the image display device with an inspection voltage value for driving and displaying an inspection image on the image display device;
An inspection image data acquisition step of acquiring an inspection image data by causing an imaging device to image the inspection image displayed on the image display device;
The image display device is driven in a state in which detection of the voltage factor defect is impossible with the first background voltage value that is higher or lower than the inspection voltage value. A first background image display step of displaying a first background image on the image display device;
A first background image is displayed on the image display device by driving the image display device with the other second background voltage value that is higher or lower than the inspection voltage value. 2 background image display steps;
A background image data acquisition step of causing the imaging device to capture the first background image and the second background image data respectively obtained by causing the imaging device to capture the first background image and the second background image displayed on the image display device. When,
The inspection image data and the first background image data are differentiated for each corresponding pixel to generate first difference image data, and the inspection image data and the second background image data are associated with each corresponding pixel. A shading correction step for taking a difference between the two and generating second difference image data;
A defect detection method comprising: a defect detection step of detecting a display defect of the image display device based on the first difference image data and the second difference image data. In the defect detection method according to claim 1 or 2,
In the inspection image data acquisition step and the background image data acquisition step, light reception at the time of imaging by the imaging device is performed so that the average values of the pixel values of all the pixels in the inspection image data and the background image data are substantially the same. A defect detection method characterized in that time is set to be different. In the defect detection method according to claim 1 or 2,
In the inspection image data acquisition step and the background image data acquisition step, the light amounts of the incident light beams are different so that the average values of the pixel values of all the pixels in the inspection image data and the background image data are substantially the same. The defect detection method characterized by being set to. In the defect detection method in any one of Claims 1-4,
The shading correction step includes
The level of each pixel value for each pixel in the correction target image data of either the inspection image data or the background image data is determined using any one of the inspection image data and the background image data using a predetermined approximate expression. A corrected image data generation procedure for generating corrected image data by approximating the level of each pixel value for each pixel in the other non-correction target image data;
A defect detection method comprising: a difference image data generation procedure for calculating a difference for each pixel corresponding to the corrected image data and the non-correction target image data and generating difference image data. The defect detection method according to claim 5,
In the corrected image data generation procedure,
Each pixel value for each pixel in the corrected image data is X ′ _{(m, n)} ,
Each pixel value for each pixel in the correction target image data is X _{1 (m, n)} ,
The average value of each pixel value X _{1 (m, n)} for each pixel in the correction target image data is X _1a ,
The standard deviation of the correction target pixel for each pixel in the image data values X _{1 (m, n)} and S _1,
Each pixel value for each pixel in the non-correction target image data is X _{2 (m, n)} ,
The average value of each pixel value X _{2 (m, n)} for each pixel in the non-correction target image data is X _2a ,
When the standard deviation of each pixel value X _{2 (m, n)} for each pixel in the non-correction target image data is S ₂ , using the approximate expression of the following expression (1),

A defect detection method for generating the corrected image data. The defect detection method according to claim 5,
In the corrected image data generation procedure,
Each pixel value for each pixel in the corrected image data is X ′ _{(m, n)} ,
Each pixel value for each pixel in the correction target image data is X _{1 (m, n)} ,
The average value of each pixel value X _{1 (m, n)} for each pixel in the correction target image data is X _1a ,
The standard deviation of the correction target pixel for each pixel in the image data values X _{1 (m, n)} and S _1,
Each pixel value for each pixel in the non-correction target image data is X _{2 (m, n)} ,
The average value of each pixel value X _{2 (m, n)} for each pixel in the non-correction target image data is X _2a ,
When the standard deviation of each pixel value X _{2 (m, n)} for each pixel in the non-correction target image data is S ₂ , the approximate expression of the following expression (2) is used:

A defect detection method for generating the corrected image data. In the defect detection method according to any one of claims 5 to 7,
The image display device is driven so that the outermost peripheral pixel in the image display device has a predetermined luminance value, and the other pixels have a luminance value smaller than the predetermined luminance value. An outermost peripheral image display step for displaying
An outermost periphery image data acquisition step of causing the imaging device to capture an outermost periphery image displayed on the image display device and acquiring outermost periphery image data;
Recognizing an outer edge position corresponding to the outermost peripheral pixel based on the outermost peripheral image data, and including an inspection target area determination step for determining the inside of the outer edge position as an inspection target area,
The shading correction step includes an inspection target region extraction procedure for generating the correction target extraction image data and the non-correction target extraction image data by extracting the inspection target regions of the correction target image data and the non-correction target image data, respectively. ,
In the correction image data generation procedure, the correction image data is generated based on the correction target extraction image data and the non-correction target extraction image data,
In the difference image data generation procedure, a difference is obtained for each pixel corresponding to the corrected image data and the non-correction target extraction image data, and the difference image data is generated. A defect detection apparatus that detects a display defect of an image display device that displays an image by modulating an incident light beam for each pixel by applying a voltage of a predetermined voltage value,
A light source device for irradiating the image display device with a light beam;
An imaging device for imaging a light flux via the image display device;
A control device for driving and controlling the image display device and the imaging device;
The controller is
When the voltage display defect that can be generated in an image when a voltage having a predetermined voltage value is present in the image display device, the image display device is enabled in a state that enables detection of the voltage cause defect. An inspection image display control unit for driving the image display device with an inspection voltage value for driving and displaying an inspection image on the image display device;
Unlike the inspection voltage value, the image display device is driven with a background voltage value for driving the image display device in a state in which detection of the voltage factor defect is impossible, and a background image is displayed on the image display device. A background image display control unit for displaying
An inspection image data acquisition unit for acquiring inspection image data by causing the imaging device to image an inspection image displayed on the image display device;
A background image data acquisition unit that acquires background image data by causing the imaging device to capture a background image displayed on the image display device;
A shading correction unit that takes the difference for each pixel corresponding to the inspection image data and the background image data, and generates difference image data;
A defect detection apparatus comprising: a defect detection unit that detects a display defect of the image display device based on the difference image data. A defect detection apparatus that detects a display defect of an image display device that displays an image by modulating an incident light beam for each pixel by applying a voltage of a predetermined voltage value,
A light source device for irradiating the image display device with a light beam;
An imaging device for imaging a light flux via the image display device;
A control device for driving and controlling the image display device and the imaging device;
The controller is
When the voltage display defect that can be generated in an image when a voltage having a predetermined voltage value is present in the image display device, the image display device is enabled in a state that enables detection of the voltage cause defect. An inspection image display control unit for driving the image display device with an inspection voltage value for driving and displaying an inspection image on the image display device;
The image display device is driven in a state in which detection of the voltage factor defect is impossible with the first background voltage value that is higher or lower than the inspection voltage value. A first background image is displayed on the image display device, and the image display device is driven with the other second background voltage value among the voltage value higher and lower than the inspection voltage value. A background image display control unit for displaying a second background image on the image display device;
An inspection image data acquisition unit for acquiring inspection image data by causing the imaging device to image an inspection image displayed on the image display device;
A background image data acquisition unit that acquires the first background image data and the second background image data by causing the imaging device to respectively capture the first background image and the second background image displayed on the image display device. When,
The inspection image data and the first background image data are differentiated for each corresponding pixel to generate first difference image data, and the inspection image data and the second background image data are associated with each corresponding pixel. A shading correction unit that takes the difference and generates second difference image data;
A defect detection apparatus comprising: a defect detection unit that detects a display defect of the image display device based on the first difference image data and the second difference image data.

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