WO2018146807A1

WO2018146807A1 - Display device

Info

Publication number: WO2018146807A1
Application number: PCT/JP2017/005117
Authority: WO
Inventors: 洋和田口
Original assignee: 三菱電機株式会社
Priority date: 2017-02-13
Filing date: 2017-02-13
Publication date: 2018-08-16

Abstract

The purpose of the present invention is to provide a display device for which variations in display-unit luminance and chromacity can be improved. This display device comprises: a first display unit (1) having disposed therein a plurality of first light-emitting elements (1a) the lighting of which is controlled by a first driving unit (6); a second display unit (2) having disposed therein a plurality of second light-emitting elements (2a) the lighting of which is controlled by a second driving unit (9); a luminance measuring unit (100) for measuring the luminance of the plurality of second light-emitting elements (2a); and a luminance correcting unit (18) for correcting luminance information on the basis of the measured luminance, such luminance information being included in a signal associated with the lighting control of each of the first light-emitting elements (1a). The first driving unit (6) controls the lighting of each of the first light-emitting elements (1a) on the basis of the corrected signal. The luminance measuring unit (100) includes a light-receiving element (10) and an integrator element (20). The light-receiving element (10) receives the light rays emitted from the plurality of second light-emitting elements (2a) and thereby measures luminance. The integrator element (20) is disposed between the second display unit (2) and the light-receiving element (10). The cross-section of the integrator element has a cylindrical shape larger than the region in which the plurality of second light-emitting elements (2a) are disposed, and the light rays emitted from the plurality of second light-emitting elements (2a) pass through the inside of such cylindrical shape and are guided to the light-receiving element (10).

Description

Display device

The present invention relates to a display device including a display unit having a light emitting element.

2. Description of the Related Art An LED display device that displays an image using a plurality of LEDs (Light Emitting Diodes) is used in many applications such as outdoor and indoor advertisement display due to LED technology development and cost reduction. Specifically, conventionally, LED display devices have been mainly used for displaying natural images and animated moving images. However, in recent years, with the narrowing of the pixel pitch, it has become possible to maintain the image quality even when the viewing distance is short. Therefore, it is also used indoors as a conference room and a monitoring application. Of these, in surveillance applications, a personal computer image close to a still image is often displayed.

Since the luminance of the LEDs decreases as the cumulative lighting time becomes longer, a difference occurs in the cumulative lighting time of each LED and consequently the luminance reduction rate of each LED depending on the content of the displayed image. As a result, pixel luminance variations and chromaticity variations occur as the cumulative lighting time increases.

In order to reduce such luminance variation and chromaticity variation, a technique has been proposed in which the luminance of the LED display surface, that is, the surface on which a desired image is displayed to the observer is corrected by the reference LED (for example, a patent). Reference 1). The reference LED is mounted on the surface opposite to the surface on which the plurality of LEDs constituting the LED display surface are mounted out of the two surfaces of the circuit board.

JP 2014-102484 A

The above-mentioned reference LED that is driven in the same manner as the driving of a plurality of LEDs mounted on the display surface side deteriorates in the same manner as the LED on the display surface side. The LED display device can detect the luminance of the reference LED with an optical sensor, measure the luminance reduction rate, and correct the luminance of the LED on the display surface side based on the luminance reduction rate. With this technique, the LED display device can correct the luminance variation and chromaticity variation of the LED display surface caused by the difference in the lighting time of the LED. However, only one reference LED is mounted per circuit board on which a plurality of LEDs on the display surface side are mounted, and when the variation in the characteristics of each LED is large, the luminance variation is accurately corrected. It is difficult. Furthermore, when one of the reference LEDs is suddenly turned off due to an accidental failure or the like, it is impossible to measure the LED luminance reduction rate. For this reason, the LED display device cannot correct luminance variations on the LED display surface.

An LED display device in which a plurality of reference LEDs are mounted makes it possible to use the average value of the luminance of each reference LED for the above correction. That is, the LED display device can suppress adverse effects due to variations in the characteristics of the LEDs. Furthermore, even when one of the plurality of reference LEDs suddenly turns off due to an accidental failure or the like, the LED display device detects the number of the reference LEDs that have failed, and the brightness of the remaining reference LEDs that are continuously lit. It is possible to continue the correction of the luminance variation of the LED display surface by measuring. However, if the light sensor is simply arranged in front of the plurality of reference LEDs, the brightness of each reference LED detected by the light sensor is greatly different depending on the relative position between each reference LED and the light sensor. This is because the light distribution of each reference LED changes, that is, the light intensity with respect to the radiation angle changes with respect to the light emitted from each reference LED. For this reason, correction of luminance variation on the LED display surface is largely governed by the characteristics of the reference LED that contributes greatly to the luminance detected by the optical sensor.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a display device in which the effect of suppressing the luminance variation and chromaticity variation of the display unit is improved.

The display device according to the present invention includes a first display unit in which a plurality of first light emitting elements whose lighting is controlled by a first driving unit and a plurality of second light emitting elements whose lighting is controlled by a second driving unit. The second display unit in which is arranged, the luminance measuring unit that measures the luminance of the plurality of second light emitting elements, and the lighting control of each of the plurality of first light emitting elements based on the luminance measured by the luminance measuring unit A luminance correction unit that corrects luminance information included in the related signal. The first driving unit controls lighting of each of the plurality of first light emitting elements based on the signal whose luminance information is corrected by the luminance correcting unit. The luminance measurement unit includes a light receiving element and an integrator element. The light receiving element receives the light emitted from the plurality of second light emitting elements and measures the luminance. The integrator element is provided between the second display unit and the light receiving element, has a cylindrical shape whose cross section is larger than a region where the plurality of second light emitting elements are arranged, and is emitted from the plurality of second light emitting elements. The light beam is guided through the cylindrical shape to the light receiving element.

According to the present invention, it is possible to provide a display device in which the effect of suppressing the luminance variation and chromaticity variation of the display unit is improved. In particular, the display device can suppress the adverse effect of the characteristic variation of the light emitting element and can increase the accuracy of correcting the luminance variation.

The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

1 is a block diagram illustrating a configuration of an LED display device according to Embodiment 1. FIG. 3 is a block diagram showing a processing circuit of the LED display device in Embodiment 1. FIG. It is a figure which shows an example of the relationship between the 2nd cumulative lighting time of 2nd LED, and an average luminance fall rate. It is a figure which shows an example of the relationship between the 1st cumulative lighting time of 1st LED, and a luminance fall rate. FIG. 3 is a schematic diagram showing an integrator element in the first embodiment. FIG. 3 is a schematic diagram illustrating a cross section of a second LED display unit and a luminance measurement unit in the first embodiment. 6 is a schematic diagram illustrating an example of a light distribution of first LEDs and second LEDs in Embodiment 2. FIG. 6 is a schematic diagram showing a cross section of a second LED display unit and a luminance measurement unit in Embodiment 2. FIG. FIG. 10 is a schematic diagram showing cross sections of a second LED display unit and a luminance measurement unit in a modification of the second embodiment. FIG. 10 is a schematic diagram showing an integrator element in a third embodiment.

Embodiments of the display device according to the present invention will be described below. In each embodiment, the display device will be described by taking an LED display device as an example.

<Embodiment 1>
FIG. 1 is a block diagram illustrating a configuration of an LED display device 300 according to the first embodiment. The LED display device 300 includes a first LED display unit 1, a second LED display unit 2, an input terminal 3, a video signal processing unit 4, a signal correction unit 5, a first drive unit 6, and a lighting time storage unit 7. A signal generation unit 8, a second drive unit 9, a luminance measurement unit 100, an average luminance calculation unit 13, a luminance transition storage unit 11, and a correction coefficient calculation unit 12. The luminance correction unit 18 includes a signal correction unit 5 and a correction coefficient calculation unit 12.

First, the 1st LED display part 1 and the 2nd LED display part 2 are demonstrated. For example, an LED display panel is applied to the first LED display unit 1 and the second LED display unit 2.

The first LED display unit 1 includes a plurality of first LEDs 1a. In the first embodiment, a total of 16 first LEDs 1a of 4 vertical x 4 horizontal are arranged in a matrix. However, the number of 1st LED1a is not restricted to this.

The first LED display unit 1 displays a desired image such as characters and figures. The 1st LED display part 1 is driven based on the 1st drive signal output from the 1st drive part 6 mentioned later. The first drive signal includes a display pattern, a drive pattern, and drive data. That is, lighting control of each first LED 1a is performed by the first drive signal output from the first drive unit 6.

The second LED display unit 2 has a plurality of second LEDs 2a. In the first embodiment, a total of four second LEDs 2a of 2 vertical x 2 horizontal are arranged in a matrix. Although the number of 2nd LED2a is not restricted to this, the 2nd LED display part 2 is comprised from 2 or more 2nd LED2a.

The second LED display unit 2 is driven based on a second drive signal output from a second drive unit 9 described later. The second drive signal includes a display pattern, a drive pattern, and drive data. That is, lighting control of each second LED 2a is performed by the second drive signal output from the second drive unit 9.

The second LED display unit 2 performs display for the LED display device 300 to measure or predict the transition of the luminance of the first LED display unit 1. Note that the transition of luminance is, for example, the luminance maintenance rate indicating the current luminance when the initial luminance is 100%, or the luminance reduction rate that is inversely related to the luminance maintenance rate (= 100% −luminance maintenance rate). Etc. In the following description, it is assumed that the luminance decrease rate is applied to the luminance transition.

The luminance reduction rate of each second LED 2a is equivalent to the luminance reduction rate of each first LED 1a. That is, the brightness reduction rate of each second LED 2a is the same as or similar to the brightness reduction rate of each first LED 1a. For example, LEDs having the same manufacturing lot are applied to the first LEDs 1a and the second LEDs 2a. Alternatively, for example, the first LED 1a and the second LED 2a are applied with LEDs having the same BIN code for classifying the LEDs according to luminance, wavelength, and the like. Each of the first LEDs 1a and each of the second LEDs 2a have similar characteristics such as luminance and wavelength, and the luminance reduction rates of both are the same.

In addition, in the first embodiment, the display operation, ie, driving of the first LED display unit 1 and the display operation, ie, driving, of the second LED display unit 2 are performed in parallel. Thereby, 1st LED1a and 2nd LED2a are lighted on in the same environment, and it is possible to make both luminance fall rates close to each other.

Next, each component and function will be described in order from the input terminal 3 shown in FIG.

The input terminal 3 receives a video signal from the outside. The video signal processing unit 4 selects an area necessary for display based on the video signal received at the input terminal 3 and performs processing such as gamma correction.

The signal correction unit 5 corrects the luminance information included in the output signal of the video signal processing unit 4 using a correction coefficient input from the correction coefficient calculation unit 12 described later. By this correction, the signal correction unit 5 can substantially correct the first drive signal output from the first drive unit 6 to the first LED display unit 1, and consequently the luminance of the one or more first LEDs 1a. is there.

The first drive unit 6 generates a first drive signal for driving the first LED display unit 1 based on the output signal corrected by the signal correction unit 5. The first drive unit 6 drives the first LED display unit 1 by outputting the first drive signal to the first LED display unit 1. That is, the 1st drive part 6 performs lighting control of each 1st LED1a.

The lighting time storage unit 7 stores the first cumulative lighting time of each of the first LEDs 1a. The first cumulative lighting time is a time obtained by cumulatively adding times when the first LEDs 1a are turned on.

The signal generation unit 8 generates a signal for generating the second drive signal of the second LED display unit 2 based on the output signal corrected by the signal correction unit 5.

The second drive unit 9 generates a second drive signal for driving the second LED display unit 2 based on the signal generated by the signal generation unit 8. The second drive unit 9 drives the second LED display unit 2 by outputting the second drive signal to the second LED display unit 2. That is, the 2nd drive part 9 performs lighting control of each 2nd LED2a.

The second drive unit 9 includes a detection unit (not shown). A detection part determines the lighting state of each 2nd LED2a which the 2nd LED display part 2 has. For example, the detection unit detects a failure state or a normal state of each second LED 2a. And a detection part counts the number of each 2nd LED2a currently lighted normally.

The luminance measuring unit 100 includes a light receiving element 10 and an integrator element 20. In the first embodiment, the light receiving element 10 is disposed to face the second LED display unit 2. The light receiving element 10 receives the light emitted from the plurality of second LEDs 2a and measures the luminance thereof. For the light receiving element 10, for example, a measuring device such as a photodiode capable of measuring light having a wavelength in the visible range is applied.

The integrator element 20 is provided between the second LED display unit 2 and the light receiving element 10. The integrator element 20 has a cylindrical shape whose cross section is larger than a region where the plurality of second LEDs 2a are arranged. Although details will be described later, the integrator element 20 is, for example, a light tunnel having a cylindrical shape with a rectangular cross section. The integrator element 20 has a mirror formed by depositing a reflective film on four inner walls that form a rectangular cross section. In FIG. 1, for convenience of explanation, the integrator element 20 is shown in a perspective view. The integrator element 20 takes in the light emitted from the plurality of second LEDs 2a of the second LED display unit 2 into the cylindrical shape and guides it to the light receiving element 10 as a leveled light.

The average luminance calculation unit 13 calculates the average luminance of each second LED 2a. The average luminance is obtained by dividing the luminance of at least one second LED 2a that is normally lit among the plurality of second LEDs 2a by the number of each second LED 2a that is normally lit as counted by the detection unit of the second drive unit 9. Is calculated. The luminance of the at least one second LED 2a that is normally lit is measured by the luminance measuring unit 100.

The luminance transition storage unit 11 stores the average luminance of each second LED 2a calculated by the average luminance calculation unit 13 and the second cumulative lighting time of each second LED 2a in association with each other. Here, the second cumulative lighting time is a time obtained by cumulatively adding the times when the second LEDs 2a are turned on.

In the measurement by the luminance measurement unit 100, the calculation by the average luminance calculation unit 13, and the storage by the luminance transition storage unit 11, at least one second LED 2a among the plurality of second LEDs 2a of the second LED display unit 2 is lit. It is done at any time.

The correction coefficient calculation unit 12 calculates a luminance reduction rate from the first cumulative lighting time stored in the lighting time storage unit 7 and the average luminance and the second cumulative lighting time of the second LED 2a stored in the luminance transition storage unit 11. To do. The correction coefficient calculation unit 12 calculates a luminance correction coefficient based on the luminance reduction rate.

Here, the luminance correction unit 18 in FIG. 1 includes the signal correction unit 5 and the correction coefficient calculation unit 12 described above. That is, the luminance correction unit 18 is based on the first cumulative lighting time stored in the lighting time storage unit 7 and the average luminance and the second cumulative lighting time of the second LED 2a stored in the luminance transition storage unit 11. A correction coefficient is calculated. Then, the brightness correction unit 18 corrects the brightness information included in the output signal of the video signal processing unit 4 using the correction coefficient. As a result, the first drive signal output from the first drive unit 6 to the first LED display unit 1 and the brightness of the first LED 1a are corrected.

In the first embodiment, the plurality of first cumulative lighting times of the plurality of first LEDs 1a are different. The second cumulative lighting time of the second LED 2a is set to the longest first cumulative lighting time among the first cumulative lighting times of the plurality of first LEDs 1a. That is, the length of the second cumulative lighting time of the second LED 2a is controlled to be equal to or longer than the length of the first cumulative lighting time of the first LED 1a. Further, the plurality of second LEDs 2 a are driven based on the same second drive signal from the second drive unit 9, whereby the plurality of second LEDs 2 a are all subjected to the same lighting control and the like. That is, the second cumulative lighting times of the plurality of second LEDs 2a are not different individually and are the same time.

Then, the luminance correction unit 18 includes the longest first cumulative lighting time among the plurality of first cumulative lighting times stored in the lighting time storage unit 7 and the luminance reduction rate of the second LED 2 a stored in the luminance transition storage unit 11. The correction is performed based on the second cumulative lighting time.

FIG. 2 is a diagram illustrating an example of the processing circuit 90 provided in the LED display device 300. The processing circuit 90 includes a memory 91 and a processor 92 that are connected to each other. The functions of the video signal processing unit 4, the signal correction unit 5, the first drive unit 6, the signal generation unit 8, the second drive unit 9, the average luminance calculation unit 13, and the correction coefficient calculation unit 12 are described as a program. And stored in the memory 91. The processor 92 reads out and executes the program stored in the memory 91, thereby realizing each operation of each unit described above. The functions of the lighting time storage unit 7 and the luminance transition storage unit 11 are realized by the memory 91, for example.

Next, the luminance correction operation performed by the LED display device 300 will be described.

The luminance transition storage unit 11 stores the average luminance calculated by the average luminance calculation unit 13 and the second cumulative lighting time of the second LED 2a in association with each other. The correction coefficient calculation unit 12 of the luminance correction unit 18 reads the average luminance and the second cumulative lighting time, and calculates the luminance reduction rate.

FIG. 3 is a diagram illustrating an example of the relationship between the second cumulative lighting time of the second LED 2a and the luminance reduction rate. In addition, the logarithmic scale is applied to the scale of the 2nd cumulative lighting time of FIG. The luminance reduction rate of the second LED 2a shown in FIG. 3 is the average luminance reduction rate of the plurality of second LEDs 2a as described above.

As shown in FIG. 3, as the lighting time increases, the average luminance reduction rate of the second LED 2a increases. That is, the brightness of each second LED 2a decreases.

As described above, each first LED 1a of the first LED display unit 1 has characteristics similar to each second LED 2a to such an extent that the luminance reduction rate can be identified with the luminance reduction rate of each second LED 2a. FIG. 4 is a diagram illustrating an example of the relationship between the first cumulative lighting time of the first LED 1a and the luminance reduction rate. The logarithmic scale is applied to the scale of the lighting time of FIG. 4 like FIG. Note that a total of 16 first LEDs 1a are arranged in the first LED display unit 1, but for convenience of explanation, FIG. 1 shows the brightness of each of the three representative first LEDs 1a having different first cumulative lighting times. Only the rate of decline is displayed.

As shown in FIG. 4, the luminance of each first LED 1a also decreases with the lighting time, like the luminance of the second LED 2a. However, since there is a difference in the first cumulative lighting time of each of the plurality of first LEDs 1a, the respective luminance reduction rates are different. If the brightness of each of the plurality of first LEDs 1a is not corrected, brightness variation occurs in the display of the first LED display unit 1.

Therefore, the correction coefficient calculation unit 12 reads the luminance corresponding to the lighting time of the second LED 2a that is the same as or close to the lighting time of the first LED 1a stored in the lighting time storage unit 7, and calculates the luminance reduction rate. The lighting time of the first LED 1a is an actual measurement time. Further, as described above, the luminance reduction rate of each second LED 2a is equal to the luminance reduction rate of each first LED 1a. Therefore, the LED display device 300 according to the first embodiment can calculate the luminance decrease rate of each first LED 1a without requiring actual measurement of the luminance of each first LED 1a.

At this time, the correction coefficient calculation unit 12 obtains the largest luminance reduction rate as the maximum luminance reduction rate among the plurality of calculated luminance reduction rates of the first LEDs 1a. Further, the correction coefficient calculation unit 12 refers to the lighting time storage unit 7 and the luminance transition storage unit 11, and for all the first LEDs 1a of the first LED display unit 1, a theoretical luminance reduction rate with respect to the first cumulative lighting time, A correction coefficient for each first LED 1a is obtained based on the maximum luminance reduction rate described above.

The luminance correction unit 18 corrects the luminance information included in the output signal of the video signal processing unit 4 using the correction coefficient for each first LED 1a. By this correction, the first drive signal is substantially corrected. The LED display device 300 corrects the luminance of each of the plurality of first LEDs 1a as indicated by arrows in FIG. That is, the LED display device 300 corrects the luminance of all the first LEDs 1a to the same luminance indicated by a one-dot chain line in FIG.

According to the LED display device 300 according to the first embodiment that performs the correction as described above, the luminance after correction of the first LED display unit 1 is reduced as a whole as compared with the luminance before correction. The brightness | luminance of 1st LED1a can be unified into the brightness | luminance of LED with the longest lighting time, ie, the brightness | luminance with the largest brightness | luminance fall rate. For this reason, brightness uniformity and white balance can be maintained as a whole of the first LED display unit 1, and brightness variations and chromaticity variations can be suppressed.

Next, an example of the configuration of the integrator element 20 will be described. As shown in FIG. 1, in the first embodiment, the light receiving element 10 of the luminance measuring unit 100 is disposed so as to face the second LED display unit 2 via the integrator element 20, and the luminance of the plurality of second LEDs 2 a. Measure.

FIG. 5 is a schematic diagram showing the integrator element 20. The integrator element 20 is composed of, for example, four rectangular mirrors 201. A reflective film is formed on one surface 201 a of the mirror 201. The integrator element 20 is a light tunnel 200 that is fixed so that the one surface 201a having the reflective film functions as a reflective surface when the one surface 201a is located on the inner surface and has a rectangular cross section.

FIG. 6 is a schematic diagram showing cross sections of the second LED display unit 2 and the luminance measurement unit 100. FIG. 6 includes an illustration of a plurality of light rays emitted from the second LED 2 a included in the second LED display unit 2 as an example. The plurality of light rays emitted by the second LED 2a are taken into the light tunnel 200 from the entrance 202 and propagate while repeating reflection on the reflection surface of the inner wall. Thereby, each light beam is superimposed and made uniform. Each light beam exits from an exit port 203 opposite to the entrance port 202. The light receiving element 10 receives the uniformed light beam and measures the luminance of the second LED 2a.

As described above, an LED having the same manufacturing lot as that of each first LED 1a or an LED having the same BIN code for classifying the LEDs according to luminance or the like is applied to each second LED 2a. Therefore, the characteristics such as the luminance of each first LED 1a and each second LED 2a are substantially the same.

The light beam emitted from each second LED 2a propagates through the inside without leaking out of the light tunnel 200, and reaches the light receiving element 10 as a uniformed light beam. Therefore, the ratio which each 2nd LED2a contributes with respect to the brightness | luminance which the brightness | luminance measurement part 100 measures is substantially the same. That is, the measured luminance is not strongly influenced by the characteristics of the specific second LED 2a among the plurality of second LEDs 2a. The luminance measured by the luminance measuring unit 100 is a value based on the characteristics of the second LEDs 2a in which the characteristics are equally averaged. Thus, the light tunnel 200 suppresses the influence of the characteristic variation of each second LED 2a.

The LED display device 300 can continue correcting the brightness of each first LED 1a even when one of the plurality of second LEDs 2a is turned off due to an accidental failure or the like. This is because, as described above, the average luminance calculation unit 13 calculates the average luminance of each second LED 2a in the normal state, and the correction coefficient calculation unit 12 calculates the luminance reduction rate and the correction coefficient from the average luminance. The contribution rate of each second LED 2a is substantially the same with respect to the luminance measured by the luminance measuring unit 100. Therefore, the fact that one of the plurality of second LEDs is turned off does not affect the average luminance of each second LED 2a calculated by the average luminance calculation unit 13. The LED display device 300 can continue to accurately correct the luminance of each first LED 1a.

The second LED display unit 2 and the light receiving element 10 in the first embodiment are arranged adjacent to the entrance 202 and the exit 203 of the light tunnel 200, respectively. Therefore, no light other than the light emitted by each second LED 2 a is incident on the light receiving element 10 of the luminance measuring unit 100. The LED display device 300 can accurately correct the luminance of each first LED 1a without being affected by surrounding stray light.

In the prior art, when there is a large variation in the characteristics of LEDs for luminance measurement or when a failure occurs, it is difficult to uniformly control the luminance and chromaticity of the entire LED display surface. However, the LED display device 300 according to the first embodiment performs luminance measurement of the LEDs for luminance measurement via the light tunnel 200. For this reason, the LED display device 300 eliminates the influence of variations in the characteristics of LEDs for luminance measurement and the effect of luminance reduction due to failure, so that the luminance and chromaticity of the entire LED display device do not shift and are always stable and uniform. Can be controlled.

In summary, the display device according to the first embodiment is lit by the first display unit in which a plurality of first light emitting elements whose lighting is controlled by the first driving unit 6 and the second driving unit 9 are lit. And a second display unit on which a plurality of second light emitting elements to be controlled are arranged. The plurality of first light emitting elements are a plurality of first LEDs, and the first display unit is a first LED display unit in which a plurality of first LEDs are arranged. The plurality of second light emitting elements are a plurality of second LEDs, and the second display unit is a second LED display unit in which a plurality of second LEDs are arranged. That is, the display device in the first embodiment is the LED display device 300.

The LED display device 300 includes a luminance measurement unit 100 that measures the luminance of the plurality of second LEDs 2a, and a signal related to lighting control of each of the plurality of first LEDs 1a based on the luminance measured by the luminance measurement unit 100. And a luminance correction unit 18 that corrects luminance information to be corrected. In the first embodiment, a signal related to the lighting control of each of the plurality of first LEDs 1 a is an output signal of the video signal processing unit 4.

The first driving unit 6 controls lighting of each of the plurality of first LEDs 1a based on the signal whose luminance information is corrected by the luminance correcting unit 18. The luminance measuring unit 100 is provided between the light receiving element 10 that receives the light emitted from the plurality of second LEDs 2a and measures the luminance, and the second LED display unit 2 and the light receiving element 10, and has a cross section of the plurality of second LEDs 2a. And an integrator element 20 that guides the light emitted from the plurality of second LEDs 2a to the light receiving element 10 through the inside of the cylindrical shape.

With the configuration as described above, the light beam emitted from each second LED 2 a reaches the light receiving element 10 without leaking out of the integrator element 20. In addition, light other than the light emitted from each second LED 2a does not enter the light receiving element 10, and the influence of surrounding stray light is eliminated. Further, the light emitted from each second LED 2 a is leveled by the integrator element 2 and enters the light receiving element 10. Therefore, the LED display device 300 calculates the luminance maintenance rate of each first LED 1a after suppressing the influence of variation in characteristics of each second LED. The LED display device 300 reliably measures the light rays emitted from the plurality of second LEDs 2a and calculates the luminance transition (luminance maintenance rate or luminance reduction rate) of the first LED 1a with high accuracy. The LED display device 300 can suppress luminance variation and chromaticity variation of the first LED display unit 1 in a state where a desired image is displayed on the first LED display unit 1.

The display device (LED display device 300) according to the first embodiment includes a lighting time storage unit 7 that stores the first cumulative lighting time of each of the plurality of first light emitting elements (first LEDs 1a), and the luminance measurement unit 100. Is further provided with a luminance transition storage unit 11 that stores the luminance measured by the above and the second cumulative lighting time of the plurality of second light emitting elements (second LEDs 2a) in association with each other. The brightness correction unit 18 is based on the first cumulative lighting time of each of the plurality of first LEDs 1a stored in the lighting time storage unit 7, the luminance stored in the luminance transition storage unit 11, and the second cumulative lighting time. Luminance information included in a signal related to lighting control of each of the plurality of first LEDs 1a is corrected.

With the above configuration, the luminance of the first LED display unit 1 is corrected by the luminance transition (luminance maintenance rate or luminance reduction rate) corresponding to the first cumulative lighting time of each first LED 1a. Therefore, the LED display device 300 can correct the luminance of the first LED display unit 1 with high accuracy.

Moreover, the 2nd drive part 9 with which the display apparatus (LED display apparatus 300) in this Embodiment 1 is provided determines each lighting state of several 2nd light emitting element (2nd LED2a), and each is a normal state. A detection unit for counting the number of second LEDs 2a is included. The LED display device 300 includes the number of normal second LEDs 2a counted by the detection unit and the luminance of at least one second LED 2a in the normal state among the plurality of second LEDs 2a measured by the luminance measurement unit 100. An average luminance calculation unit 13 that calculates the average luminance of each second LED 2a is further provided. The luminance transition storage unit 11 stores the average luminance calculated by the average luminance calculation unit 13 and the second cumulative lighting time in association with each other. The luminance correction unit 18 includes a first cumulative lighting time of each of the plurality of first light emitting elements (first LEDs 1a) stored in the lighting time storage unit 7, an average luminance and a second cumulative value stored in the luminance transition storage unit 11. Based on the lighting time, the luminance information included in the signal related to the lighting control of each of the plurality of first LEDs 1a is corrected.

With the configuration as described above, the LED display device 300 uses the average brightness of the remaining second LEDs 2a that are normally lit even when some of the plurality of second LEDs 2a are not lit due to accidental failure or the like. The brightness correction of the first LED display unit 1 can be continued. Further, the LED display device 300 can suppress the luminance correction error due to the characteristic variation of each of the second LEDs 2a by measuring the luminance after averaging the characteristics of all the second LEDs 2a. As a result, the LED display device 300 can perform brightness correction with high accuracy. When the LED display device 300 does not include the average luminance calculation unit 13, the luminance measured by the luminance measurement unit 100 is stored in the luminance transition storage unit 11 as it is.

<Embodiment 2>
The block configuration of the LED display device in the second embodiment is the same as the block configuration of the LED display device 300 shown in FIG. 1 of the first embodiment. Hereinafter, among the configurations included in the LED display device in the second embodiment, the same or similar components as those in the first embodiment are denoted by the same reference numerals.

FIG. 7 is a schematic diagram showing an example of the light distribution of the first LED 1a and the second LED 2a. The vertical direction is a radiation angle of 0 ° with respect to the light emitting surface of each of the first LED 1a and the second LED 2a. Further, the same plane as the light emitting surface has radiation angles of −90 ° and 90 °. FIG. 7 shows the luminous intensity of the light emitted by the first LED 1a and the second LED 2a at the radiation angle of −90 ° to 90 °. In FIG. 7, the light distribution Iv0 indicates the light distribution in the initial lighting of the first LED 1a and the second LED 2a. The light distribution distribution Ivt is a light distribution when the cumulative lighting time is short, and the light distribution IvT is a light distribution after the cumulative lighting time is long. In each cumulative lighting time, there is almost no difference in the amount of light per unit time emitted in all directions, that is, the luminous flux. However, as the accumulated lighting time becomes longer, the luminous intensity decreases in a small angle region and increases in a large angle region.

When the light distribution of each first LED 1a has the aging characteristics shown in FIG. 7, the observer observes an image in which luminance variation or chromaticity variation occurs as the usage time of the LED display device 300 elapses. That is, when an observer observes an image from a position away from the first LED display unit 1 or from a narrow angle range near the front of the first LED display unit 1, an image displayed by the first LED 1a having a long first cumulative lighting time. Is observed to be lower than the luminance of the image displayed by the first LED 1a having a short first cumulative lighting time.

As shown in FIG. 6, the LED display device 300 according to the first embodiment has a configuration in which the second LED display unit 2 and the luminance measurement unit 100 are arranged adjacent to the entrance port 202 and the exit port 203 of the light tunnel 200, respectively. Have. Therefore, the light beam emitted from the second LED 2 a passes through the inside of the light tunnel 200 without entering the surroundings and enters the light receiving element 10. The light distribution distribution Ivt with a short cumulative lighting time and the light distribution distribution IvT with a long cumulative lighting time shown in FIG. Therefore, there is almost no difference in the luminance measured by the luminance measuring unit 100. That is, the correction coefficient calculated by the luminance correction unit 18 based on the luminance of the second LED 2a having the short second cumulative lighting time and the luminance correction unit 18 calculated based on the luminance of the second LED 2a having the long second cumulative lighting time. The correction coefficient to be applied is almost the same. The brightness of each first LED 1a based on these correction coefficients is corrected only at the same rate. As a result, luminance variations due to aging of the first LED display unit 1 are not eliminated.

FIG. 8 is a schematic diagram showing cross sections of the second LED display unit 2 and the luminance measurement unit 101 in the second embodiment. FIG. 8 includes an illustration of light rays emitted from the second LED 2 a included in the second LED display unit 2. The luminance measuring unit 101 includes an integrator element 20 and a light receiving element 10 as in the first embodiment. However, the light tunnel 200 that is the integrator element 20 is provided with a predetermined gap between one end of the cylindrical shape, that is, between the incident port 202 and the second LED display unit 2. The other end of the cylindrical shape, that is, the emission port 203 is provided adjacent to the light receiving element 10 without a gap.

Among the light rays emitted from the second LED 2a, light rays having a large emission angle are not taken into the light tunnel 200 and do not enter the light receiving element 10. A light beam having a large radiation angle that increases with the passage of the second cumulative lighting time does not contribute to the luminance of the second LED 2 a measured by the luminance measuring unit 101. The luminance measurement unit 101 measures different luminances according to the second cumulative lighting time.

That is, the correction coefficient calculated by the luminance correction unit 18 based on the luminance of the second LED 2a and the second cumulative lighting time is calculated as a coefficient that takes into account the aging characteristics of the light distribution of the second LED 2a and the first LED 1a. . By correcting the luminance of each first LED 1a based on the correction coefficient, the luminance variation on the display surface of the first LED display unit 1 is eliminated.

Here, the distance d shown in FIG. 8 is the distance between the entrance 202 of the light tunnel 200 and the second LED display unit 2. Further, the angle θ is an angle formed by the central axis (perpendicular line) of the second LED display unit 2 and a line connecting the end of the incident port 202 and the center of the second LED display unit 2. The distance d has a relationship with the angle θ. The distance d may be determined in consideration of the environment where the first LED display unit 1 is actually installed. That is, the distance d may be determined in consideration of the relative positional relationship between the first LED display unit 1 and the observer. Here, the vertical direction with respect to the display surface of the first LED display unit 1 is an angle of 0 °, and the same surface as the display surface is an angle of −90 ° or 90 °. For example, if the observer is located within an angle range of −30 ° to 30 °, the distance d is determined so that the angle θ is approximately 30 °.

With the configuration as described above, only light rays having an emission angle of −30 to 30 ° out of the light rays emitted from the second LED 2 a of the second LED display unit 2 are taken into the light tunnel 200. And the brightness | luminance of each 1st LED1a is correct | amended based on the decreasing rate of the light beam within the said radiation angle, ie, the decreasing rate of a brightness | luminance. As a result, for an observer located within an angle range of −30 ° to 30 °, an image in which luminance variation and chromaticity variation are suppressed is displayed on the first LED regardless of the cumulative usage time of the LED display device 300. Provided to Part 1.

In summary, the integrator element 20 (light tunnel 200) included in the LED display device 300 according to the second embodiment has a cylindrical end with a gap between the second LED display unit and the other end. It is provided adjacent to the light receiving element 10.

With such a configuration, even when the light distribution of the first LED 1a and the second LED 2a has an aging characteristic, the LED display device 300 allows the observer to observe the first LED display unit 1 from a narrow range near the front. Thus, a uniform image in which luminance variation and chromaticity variation are corrected is provided. In particular, although the aging characteristics show that there is almost no difference in luminous flux as the cumulative lighting time increases, the light intensity gradually decreases in the small radiation angle region, and the light intensity gradually increases in the large radiation angle region. It is effective when it is a characteristic.

(Modification of Embodiment 2)
When the light tunnel 200 is disposed with a gap between the second LED display unit 2 and the incident port 202, there is a possibility that unnecessary unnecessary light may enter the light tunnel 200 from the gap. The unnecessary light reaches the light receiving element 10 and affects the luminance of the second LED 2 a measured by the luminance measuring unit 101. Therefore, in order to prevent the intrusion of unnecessary light, as shown in FIG. 9, the luminance measurement unit 102 is positioned between the incident port 202 and the second LED display unit 2 outside the cylindrical shape of the light tunnel 200. It is desirable to include a light shielding member 25 that surrounds the gap. It is desirable that the light shielding member 25 is disposed by connecting the second LED display unit 2 and the light receiving element 10 without any gap, and covers the entire cylindrical outer side of the light tunnel 200.

<Embodiment 3>
In the first embodiment and the second embodiment, the integrator element 20 is a light tunnel 200 configured by bonding and fixing four mirrors 201 as shown in FIG. However, the integrator element 20 is not limited thereto, and may have another configuration as long as it has a similar function.

FIG. 10 is a schematic diagram showing the light tunnel 205 in the third embodiment. The light tunnel 205 has a cylindrical shape formed by bending a single thin plate 206 made of stainless steel. One surface 206a of the thin plate 206 is a substantially mirror surface. The one surface 206a is, for example, a polished surface polished by a mirror buff. Moreover, the inner wall of the light tunnel 205 is the one surface 206a, and the cross section of the light tunnel 205 has a rectangular shape. Although the light tunnel 205 has the same function as the light tunnel 200 shown in the first embodiment, the integrator element 20 can be configured by simple processing. The light tunnel 205 is lightweight and inexpensive.

In each of the above embodiments, an example of an LED display device including a display unit in which LEDs are arranged as light emitting elements has been shown, but the present invention is not limited thereto. Even in the case of a display device including a display unit in which a self-luminous light source, for example, a plurality of solid light sources or a plurality of light sources formed by coating or vapor deposition is arranged as a light emitting element, the effects described in the above embodiments The same effect is produced.

Further, in each of the above embodiments, the signal for correcting the luminance information by the luminance correction unit 18, that is, the signal related to the lighting control of each of the plurality of first light emitting elements, is output from the video signal processing unit 4. An example of a signal has been shown, but is not limited thereto.

In the present invention, it is possible to freely combine the respective embodiments within the scope of the invention, and to appropriately modify and omit the respective embodiments.

As mentioned above, although this invention was demonstrated in detail, above-mentioned description is an illustration in all the situation, Comprising: This invention is not limited to it. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

1 1st LED display section, 1a 1st LED, 2nd LED display section, 2a 2nd LED, 5 signal correction section, 6 1st drive section, 7 lighting time storage section, 8 signal generation section, 9 2nd drive section, 10 light reception Element, 11 luminance transition storage unit, 12 correction coefficient calculation unit, 13 average luminance calculation unit, 18 luminance correction unit, 20 integrator element, 100 luminance measurement unit, 300 LED display device.

Claims

A first display unit in which a plurality of first light emitting elements whose lighting is controlled by the first driving unit (6) are arranged;
A second display unit in which a plurality of second light emitting elements whose lighting is controlled by the second driving unit (9) are arranged;
A luminance measuring unit (100) for measuring luminance of the plurality of second light emitting elements;
A luminance correction unit (18) for correcting luminance information included in a signal related to lighting control of each of the plurality of first light emitting elements based on the luminance measured by the luminance measurement unit (100); ,
The first driving unit (6) controls lighting of each of the plurality of first light emitting elements based on the signal in which the luminance information is corrected by the luminance correcting unit (18),
The brightness measuring unit (100)
A light receiving element (10) that receives light emitted from the plurality of second light emitting elements and measures the luminance;
Provided between the second display unit and the light receiving element (10), and having a cross-sectional shape larger than a region where the plurality of second light emitting elements are disposed, and from the plurality of second light emitting elements A display device including an integrator element (20) for guiding the emitted light through the cylindrical shape to the light receiving element (10).
A lighting time storage unit (7) for storing a first cumulative lighting time of each of the plurality of first light emitting elements;
A luminance transition storage unit (11) for storing the luminance measured by the luminance measurement unit (100) and the second cumulative lighting times of the plurality of second light emitting elements in association with each other;
The luminance correction unit (18) is stored in the first cumulative lighting time of each of the plurality of first light emitting elements stored in the lighting time storage unit (7) and in the luminance transition storage unit (11). The display device according to claim 1, wherein the luminance information included in the signal related to the lighting control of each of the plurality of first light emitting elements is corrected based on the luminance and the second cumulative lighting time. .
The second drive unit (9)
A detector that determines a lighting state of each of the plurality of second light emitting elements and counts the number of the second light emitting elements in a normal state;
The display device
The number of the second light emitting elements in the normal state counted by the detection unit, and at least one of the plurality of second light emitting elements measured by the luminance measurement unit (100) in the normal state. An average luminance calculation unit (13) for calculating an average luminance of each second light emitting element from the luminance of the second light emitting element;
The luminance transition storage unit (11) stores the average luminance calculated by the average luminance calculation unit (13) in association with the second cumulative lighting time,
The luminance correction unit (18) is stored in the first cumulative lighting time of each of the plurality of first light emitting elements stored in the lighting time storage unit (7) and in the luminance transition storage unit (11). The display according to claim 2, wherein the luminance information included in the signal related to the lighting control of each of the plurality of first light emitting elements is corrected based on the average luminance and the second cumulative lighting time. apparatus.
The integrator element (20) is provided with one end of the cylindrical shape having a gap between the second display unit and the other end adjacent to the light receiving element (10). Item 4. The display device according to any one of Items 3 to 3.
The display device according to any one of claims 1 to 4, wherein the cylindrical shape of the integrator element (20) has a rectangular cross section and a single plate is bent.
The plurality of first light emitting elements are a plurality of first LEDs (1a),
The first display unit is a first LED display unit (1) in which the plurality of first LEDs (1a) are arranged,
The plurality of second light emitting elements are a plurality of second LEDs (2a),
The display device according to any one of claims 1 to 5, wherein the second display unit is a second LED display unit (2) in which the plurality of second LEDs (2a) are arranged.