JP2010109784A - Stand-type scanner, imaging method and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the diameter of a rotary filter as further as possible and to miniaturize a scanner head in spite of a stand-type scanner that uses the rotary filter to separate a plurality of colors included in an optical image. <P>SOLUTION: The stand-type scanner 1 is provided with, in a scanner head 4 that is disposed spatially away from a document: a CCD 5 for converting an optical image of the document into an electric signal; a lens group 6 for forming the optical image of the document on an imaging plane of the CCD 5; and a rotary filter 7 for separating a plurality of colors included in the optical image of the document through a plurality of color filters 7a-7d arranged side by side in a rotating direction. The rotary filter 7 is disposed between two of lenses 6a-6d included in the lens group 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a stand-type scanner device such as a document camera that captures an image of a subject at a position spatially separated from the subject, an imaging method, and an imaging device.

A stand-type scanner device that captures an image of a subject at a position spatially separated from the subject is known (see, for example, Patent Document 1).
This type of stand-type scanner device includes an image sensor that converts an optical image of a subject into an electrical signal in a scanner head that is spatially separated from the subject, and an optical image of the subject that is connected to the imaging surface of the image sensor. And a lens group for imaging, and it is desired to increase the resolution of an image to be obtained and to reduce the size of a scanner head.

  Note that a two-dimensional CCD element or CMOS element can be used as the imaging element. The difference between the CCD element and the CMOS element is mainly due to the difference in the semiconductor process, and there is no difference that directly affects the problem to be solved by the present invention. Therefore, in the following description, the CCD element is used as the imaging element. Describe the case.

One method for acquiring an image with high resolution in a stand-type scanner device is to increase the number of pixels of the image sensor itself.
However, using a CCD, which is an image sensor, on a single plate and increasing the number of pixels results in poor device yield in comparison with a CCD having a small number of pixels, and makes the CCD expensive. Further, since the light receiving area of the CCD becomes large, the scanner head may be increased in size.

In order to satisfy the required performance of high image quality and high sensitivity, it is also possible to adopt a three-plate method using three image sensors. The three-plate method is a method in which one CCD is prepared for each of RGB colors, and each color optical signal separated by the spectroscopic prism is received by each CCD, and RGB color signals are extracted.
However, in this method, since three CCDs must be provided, there is a problem that the apparatus becomes expensive and the apparatus becomes large.
Further, in the three-plate method, in order to prevent color misregistration of RGB, positioning accuracy with respect to the three CCDs is also required, so that a high level of technology is required for assembly.

A CCD having a structure in which light receiving elements corresponding to RGB colors are arranged vertically is also known. This system is composed of three layers of photodetectors corresponding to primary colors, and can detect the color of one pixel in full color at the position of one element.
Therefore, it is possible to reproduce color information more accurately than the conventional methods in which the color information of three neighboring points is combined to detect the color of the pixel. In the two layers, it is necessary to transmit light of a specific wavelength, and the photoelectric element must absorb light of a specific wavelength. Therefore, the detection accuracy of each color is affected by the transmission and absorption characteristics of the spectral wavelength. Differences are likely to occur.
In addition, this type of CCD has a small quantity on the market compared to the entire imaging device, and is expensive.

Further, when shifting from a monochrome CCD to a color CCD, compatibility with past databases such as seal collation images becomes a problem. For example, in a financial institution, an image of a seal stamp is registered in advance for the purpose of stamp verification. Most of the data registered at present is based on an image acquired by a scanner having a spectral wavelength of a monochrome CCD. It has become.
For this reason, a monochrome image is generated by image processing in an image acquired by a color CCD instead of monochrome image acquisition, and a difference due to different spectral wavelength characteristics becomes a problem.
In order to eliminate this difference, it is conceivable that a single device has a color optical unit and a monochrome optical unit, but there is a problem that the device becomes expensive and the device becomes large.

Furthermore, a method of performing pixel shifting to obtain a high-resolution image is also known (see Patent Document 1).
This method shifts pixels in an oblique direction between two images and uses a point that originally has no center of the image sensor as an imaging space sample point, and is a method for improving the resolution in the horizontal and vertical directions. is there.
However, as the number of shifts increases, the overlap between pixels increases due to the shift, resulting in a decrease in resolution. When the number of shifts increases, the amount of shift repeatedly performed in micron units is highly accurate. Therefore, there is a limit to increasing the resolution only by shifting pixels.

In addition to the above, as a method of increasing the resolution, a method of combining a rotary filter and a monochrome CCD is known. Since the rotation filter can separate a plurality of colors included in the optical image of the subject by a plurality of color filters arranged in the rotation direction, color imaging can be realized even with a monochrome CCD.
For example, Patent Document 2 discloses a technique for shortening an imaging time by devising control of imaging and a filter in a configuration in which a rotary filter is disposed between a camera lens and an imaging element.
Patent Document 3 discloses a configuration in which a rotation filter is disposed between a CCD and an infrared cut filter of a video camera in order to obtain a highly accurate color still image with a black and white video camera.

JP 2001-136350 A Japanese Patent Laid-Open No. 10-051796 JP 08-1111871 A

However, in the method using the rotation filter, as shown in FIG. 9, since the rotation filter 102 is disposed between the CCD 100 and the lens group 101, the diameter of the rotation filter 102 (the dimension in the diameter direction of each color filter portion). ) Is determined by the effective imaging area of the CCD 100 or the effective transmission area of the lens 101a facing the CCD 100.
For this reason, there exists a problem that the diameter of a rotary filter becomes large and an apparatus enlarges. In particular, in a stand-type scanner device, since a rotary filter is disposed in the scanner head, it is required to reduce the diameter of the rotary filter as much as possible in order to avoid an increase in the size of the scanner head. The

  The present invention has been considered in view of the above circumstances, and uses a rotating filter to separate a plurality of colors included in an optical image, while reducing the diameter of the rotating filter as much as possible. An object of the present invention is to provide a stand-type scanner device, an imaging method, and an imaging device that can be reduced in size.

In order to achieve the above object, a stand-type scanner device of the present invention is provided with a scanner head disposed spatially away from a subject, and disposed in the scanner head.
An image sensor that converts an optical image of the subject into an electrical signal, a lens group that forms the optical image of the subject on the imaging surface of the image sensor, and a plurality of color filters arranged in the rotation direction. And a rotation filter that separates the colors of the lens, and the rotation filter is arranged between two lenses included in the lens group.

  In order to achieve the above object, the imaging method of the present invention includes an imaging device that converts an optical image of a subject into an electrical signal at a position spatially separated from the subject, and an optical image of the subject on the imaging surface of the imaging device. When imaging a subject by arranging a lens group to form an image and a rotary filter that separates a plurality of colors included in the optical image of the subject by a plurality of color filters arranged in the rotation direction, the rotational filter is arranged in the lens group. This is a method of separating a plurality of colors included in an optical image of a subject by arranging between two included lenses.

  In order to achieve the above object, an imaging device of the present invention is an imaging device disposed in a scanner head of a scanner device that images a subject, and an imaging device that converts an optical image of the subject into an electrical signal; A lens group that forms an optical image of a subject on an imaging surface of an image sensor, and a rotation filter that separates a plurality of colors included in the optical image of the subject by a plurality of color filters arranged in the rotation direction. In this configuration, the lens group is disposed between two lenses included in the lens group.

  According to the present invention, while using a rotation filter to separate a plurality of colors included in an optical image, the diameter of the rotation filter can be made as small as possible and the scanner head can be downsized.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
First, a stand-type scanner device according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view of a stand type scanner device according to a first embodiment of the present invention.
2 is a schematic side view showing an arrangement configuration in the scanner head according to the present embodiment, FIG. 3 is a partially cutaway side view showing the internal configuration of the scanner head according to the present embodiment, and FIG. FIG. 5 is a front view of a rotary filter according to the present embodiment, and FIG. 6 illustrates an opening angle of each color filter included in the rotary filter according to the present embodiment. It is a table.

As shown in FIG. 1, a stand-type scanner device 1 according to the first embodiment of the present invention is an image input device that captures an image of a document at a position spatially separated from the document without closely contacting the document (subject). is there.
Specifically, the stand-type scanner device 1 of the present embodiment includes a document table 2 on which a document is set, an arm 3 standing on the end of the document table 2, and a scanner head provided on the upper end of the arm 3. 4.
As shown in FIGS. 2 to 4, the scanner head 4 includes a CCD (imaging device) 5, a lens group 6, and a rotation filter 7. The CCD 5, the lens group 6 and the rotary filter 7 constitute an image pickup apparatus of the present invention.

The CCD 5 is an image sensor that converts an optical image of a document into an electrical signal.
Here, in the present embodiment, the CCD 5 is employed as the image pickup device, but the contents of the present invention can be similarly applied to a CMOS.
There are monochrome and color CCDs, but the stand-type scanner device 1 according to the present invention uses a rotary filter 7 to separate colors and acquire a color image. Is used.

The lens group 6 forms an optical image of the original on the imaging surface of the CCD 5.
The lens group 6 of the present embodiment includes four lenses 6a to 6d, and these lenses 6a to 6d are held by two cylindrical bodies 6e and 6f.

The rotation filter 7 is a disk-shaped member that separates a plurality of colors included in an optical image of a document by a plurality of color filters 7a to 7d arranged in the rotation direction, and is fixed at a constant speed by a rotation driving mechanism such as a motor (not shown). It is rotated by.
For example, the rotation filter 7 in which the red filter 7a, the green filter 7b, and the blue filter 7c are arranged in the rotation direction can separate the three primary colors (RGB) included in the optical image of the document. Can also obtain color images.

In the stand type scanner device 1 of the present invention, the rotary filter 7 is disposed between the two lenses 6 a to 6 d included in the lens group 6.
In this way, while the rotation filter 7 is used to separate a plurality of colors included in the optical image, the diameter of the rotation filter 7 can be made as small as possible and the scanner head 4 can be downsized. .

That is, when the rotary filter 7 is arranged between the CCD 5 and the lens group 6, the diameter of the rotary filter 7 (the dimension in the diameter direction of each color filter portion) is the effective imaging area of the CCD 5 or a lens facing the CCD 5. Determined by the effective transmission area of 6a. However, between the two lenses 6 a to 6 d included in the lens group 6, the rotation filter 7 can be arranged by selecting an arbitrary position where the luminous flux becomes thin.
Thereby, the dimension of each color filter portion of the rotary filter 7 in the diameter direction can be reduced, and consequently the diameter of the rotary filter 7 can be reduced.

The rotary filter 7 is disposed between the two lenses 6 a to 6 d including the position where the light beam becomes the narrowest in the lens group 6 among the two lenses 6 a to 6 d included in the lens group 6. It is preferable to do.
For example, in this embodiment, the light beam becomes the thinnest between the second lens 6b and the third lens 6c when viewed from the CCD 5 side, and therefore the rotary filter 7 is disposed here.
In this way, the diameter dimension of each color filter portion of the rotary filter 7 can be further reduced, so that the diameter of the rotary filter 7 can be further reduced.

The cross-sectional area of the light beam that passes through the rotary filter 7 is preferably smaller than the effective imaging area of the CCD 5 and smaller than the effective transmission area of the lens 6 a facing the CCD 5.
In this way, the diameter of the rotary filter 7 can be reliably reduced as compared with the case where the rotary filter 7 is arranged between the CCD 5 and the lens group 6.

In addition to the plurality of color filters 7a to 7c for color imaging, the rotary filter 7 preferably includes a clear filter 7d for monochrome imaging that passes the entire visible wavelength range, as shown in FIG.
In this way, monochrome imaging can be performed without separately providing a monochrome optical unit.

A monochrome image can be obtained by combining images of each color acquired with a color CCD, but even if the ratio of calculating the black and white density from each color is devised, the entire visible region is passed continuously. There is a difference in characteristics from the monochrome CCD.
For example, a seal stamp database used in a financial institution or the like often uses a monochrome CCD image as a registered image, so a monochrome image synthesized from a color CCD and a clear filter 7d are included. Comparing with a monochrome image obtained by transmission through a monochrome CCD, it is the latter that has a wavelength characteristic close to that of the original imprint database.
Therefore, the monochrome image acquisition method of this embodiment in which the clear filter 7d is combined with the monochrome CCD 5 is advantageous for an application that makes a query with a database acquired with a monochrome CCD.

In the rotary filter 7, the amount of energy (color sensitivity) of light transmitted by the filters 7a to 7d differs.
For example, in order to read a white form into the scanner and reproduce the white image in the same manner in the acquired image, it is necessary to match the level for each color, and the gain value of the acquired image for each color is changed. It is possible to combine them.
However, for example, when a white reference form image is acquired, if the blue image level is extremely small with respect to the green image, if the acquired image is lifted only by the gain value, the gain value is high. Image noise starts to stand out when it becomes too much.
For this reason, in the case of image acquisition by the blue filter 7c, it is necessary to increase the exposure time for the CCD 5 at the time of acquisition compared to other colors.

In the image acquisition using the rotation filter 7, as a method of adjusting the exposure time of each color, a method of adjusting the passing time of each color filter 7a-7d by controlling the rotation speed of the rotation filter 7, or each color filter 7a-7d. A method of adjusting the passage time of each of the color filters 7a to 7d by changing the opening angle that determines the length in the rotation direction of the color filter can be considered.
In the former method, since it is necessary to provide a fast rotation portion and a slow rotation portion in one color image acquisition, control of the rotation speed becomes complicated, and it is necessary to provide an acceleration region and a deceleration region. It is necessary to provide an extra area for acceleration / deceleration in the rotary filter 7.
For this reason, the diameter of the rotary filter 7 is increased, which may increase the size of the scanner head 4.

On the other hand, in the latter method, if the opening angle of each color filter 7a to 7d in the rotary filter 7 is set to be inversely proportional to the color sensitivity of each color, even if the rotary filter 7 is rotated at a constant speed, it corresponds to the color sensitivity. Since the exposure amount (exposure time) of each color can be changed, high-quality color imaging can be performed.
For example, the opening angle of each of the color filters 7a to 7d is set as shown in FIG. 6 according to the color sensitivity of each color.

  According to the stand type scanner apparatus 1 of the present embodiment configured as described above, the CCD 5 that converts an optical image of an original into an electric signal in the scanner head 4 that is spatially separated from the original, and the original A lens group 6 that forms an optical image of the image on the imaging surface of the CCD 5, and a rotary filter 7 that separates a plurality of colors included in the optical image of the document by a plurality of color filters 7a to 7d arranged in the rotation direction. Since the rotation filter 7 is disposed between the two lenses 6a to 6d included in the lens group 6, the rotation filter 7 is used to separate a plurality of colors included in the optical image. 7 can be made as small as possible to reduce the size of the scanner head 4.

  That is, when the rotary filter 7 is arranged between the CCD 5 and the lens group 6, the diameter of the rotary filter 7 (the dimension in the diameter direction of each color filter portion) is the effective imaging area of the CCD 5 or a lens facing the CCD 5. Although it is determined by the effective transmission area of 6a, between the two lenses 6a to 6d included in the lens group 6, the rotation filter 7 can be arranged by selecting an arbitrary position where the luminous flux becomes thin. The size of each color filter portion of the rotary filter 7 in the diameter direction can be reduced, and as a result, the diameter of the rotary filter 7 can be reduced.

The rotary filter 7 is disposed between the two lenses 6 a to 6 d including the position where the light beam becomes the narrowest in the lens group 6 among the two lenses 6 a to 6 d included in the lens group 6. Thus, the diameter of the rotary filter 7 can be further reduced.
Further, since the cross-sectional area of the light beam passing through the rotary filter 7 is smaller than the effective imaging area of the CCD 5 and smaller than the effective transmission area of the lens 6 a facing the CCD 5, it rotates between the CCD 5 and the lens group 6. Compared with the case where the filter 7 is disposed, the diameter of the rotary filter 7 can be reliably reduced.

Further, since the rotary filter 7 includes a clear filter 7d for monochrome imaging in addition to the plurality of color filters 7a to 7c for color imaging, monochrome imaging can be performed without separately providing a monochrome optical unit. .
Further, the color filters 7a to 7d of the rotary filter 7 have an opening angle that determines the length in the rotation direction based on the color sensitivity of each color. Therefore, even if the rotary filter 7 is rotated at a constant speed, the color sensitivity Accordingly, it is possible to change the exposure amount (exposure time) of each color and perform high-quality color imaging.

[Second Embodiment]
Next, a stand type scanner device according to a second embodiment of the present invention will be described with reference to FIGS. However, about the same structure as the said embodiment, description of the said embodiment is used by using the same code | symbol as the said embodiment.

FIG. 7 is a schematic perspective view showing the arrangement configuration in the scanner head according to the second embodiment of the present invention, and FIG. 8 is an explanatory view showing the operation of the pixel shifting mechanism according to this embodiment.
As shown in FIG. 7, the stand type scanner device according to the second embodiment is provided with a pixel shifting mechanism 8 for shifting the relative position between the CCD 5 and the optical image of the subject imaged on the imaging surface. It is different from the form.
In this way, the resolution can be increased without using a large CCD with a high resolution. Thereby, the enlargement of the lens group 6 and the rotary filter 7 accompanying the enlargement of the CCD can be avoided.

The pixel shifting mechanism 8 of the present embodiment moves the CCD 5, but may be a pixel shifting mechanism that optically moves the optical image without moving the CCD 5.
The pixel shifting mechanism 8 can realize pixel shifting by moving the CCD 5 by a distance that is exactly half the distance between the pixels of the CCD 5.
In the present embodiment, pixel shifting is realized by moving the CCD 5 diagonally with respect to the grid-like pixel arrangement by a half distance between the pixels.
A mirror 9 is disposed at one end of the scanner head 4 to bend the optical path by approximately 90 °.

  The preferred embodiments of the stand-type scanner device, imaging method, and imaging device according to the present invention have been described above. However, the stand-type scanner device, imaging method, and imaging device according to the present invention are limited to the above-described embodiments. However, it goes without saying that various modifications can be made within the scope of the present invention.

  The present invention can be applied to a stand-type scanner device such as a document camera that includes an image sensor, a lens group, and a rotation filter in a scanner head and images a subject at a position spatially separated from the subject, and an imaging method.

It is a perspective view of the stand type scanner device concerning a first embodiment of the present invention. It is a schematic side view which shows the arrangement configuration in the scanner head which concerns on 1st embodiment of this invention. It is a partially cutaway side view showing the internal configuration of the scanner head according to the first embodiment of the present invention. It is a perspective view which shows the internal structure of the scanner head which concerns on 1st embodiment of this invention. It is a front view of the rotary filter which concerns on 1st embodiment of this invention. It is a table | surface which shows the opening angle of each color filter with which the rotary filter which concerns on 1st embodiment of this invention is provided. It is a schematic perspective view which shows the arrangement configuration in the scanner head which concerns on 2nd embodiment of this invention. It is explanatory drawing which shows the effect | action of the pixel shift mechanism which concerns on 2nd embodiment of this invention. It is a schematic side view which shows the example of arrangement | positioning of a general rotation filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stand type scanner apparatus 2 Document stand 3 Arm 4 Scanner head 5 CCD
6 Lens group 6a-6d Lens 7 Rotation filter 7a-7c Each color filter 7d Clear filter 8 Pixel shift mechanism

Claims (10)

A scanner head arranged spatially away from the subject;
Disposed in the scanner head,
An image sensor that converts an optical image of a subject into an electrical signal;
A lens group that forms an optical image of a subject on the imaging surface of the image sensor;
A rotation filter that separates a plurality of colors included in an optical image of a subject by a plurality of color filters arranged in a rotation direction;
The rotary filter is
A stand type scanner device, which is disposed between two lenses included in the lens group.   2. The stand according to claim 1, wherein the rotary filter is disposed between two lenses including a position where the luminous flux is the thinnest in the lens group among the two lenses included in the lens group. Type scanner device.   3. The stand type scanner device according to claim 1, wherein a cross-sectional area of a light beam transmitted through the rotation filter is smaller than an effective imaging area of the imaging device and smaller than an effective transmission area of a lens facing the imaging device.   The stand type scanner device according to claim 1, wherein the rotation filter includes a clear filter for monochrome imaging in addition to a plurality of color filters for color imaging.   The stand type scanner device according to any one of claims 1 to 4, wherein each color filter of the rotation filter has an opening angle that determines a length in a rotation direction based on a color sensitivity of each color.   The stand type scanner device according to any one of claims 1 to 5, further comprising a pixel shifting mechanism that shifts a relative position between the imaging element and an optical image of a subject formed on the imaging surface. In a position spatially away from the subject,
An image sensor that converts an optical image of a subject into an electrical signal;
A lens group that forms an optical image of a subject on the imaging surface of the image sensor;
When arranging a rotation filter that separates a plurality of colors included in an optical image of a subject by a plurality of color filters arranged in a rotation direction, the subject is imaged.
An image pickup method comprising: disposing a plurality of colors included in an optical image of a subject by disposing the rotation filter between two lenses included in the lens group.   The rotary filter is disposed between two lenses including a position where the light flux becomes the narrowest in the lens group among the two lenses included in the lens group. 8. The imaging method according to 7. An imaging device disposed in a scanner head of a scanner device that images a subject,
An image sensor that converts an optical image of a subject into an electrical signal;
A lens group that forms an optical image of a subject on the imaging surface of the image sensor;
A rotation filter that separates a plurality of colors included in an optical image of a subject by a plurality of color filters arranged in a rotation direction,
The rotary filter is
An imaging apparatus, wherein the imaging apparatus is disposed between two lenses included in the lens group.   The imaging according to claim 10, wherein the rotary filter is disposed between two lenses including a position where the light flux becomes the narrowest in the lens group among the two lenses included in the lens group. apparatus.

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