JPH06169371A - Image input device - Google Patents

Abstract

PURPOSE:To compensate chromatic aberrations and simplify the structure of a lens system by varying the thickness or refractive index of a color separation filter which separate reflected light from a document into the primary colors. CONSTITUTION:An image forming lens 2 and a color separation filter part 6 are provided in the optical path 1 extending from the document to a photoelectric conversion part 5. The color separation filter part 6 consists of a 1st filter 6B which passes a blue light component, a 2nd filter 6G which passes a green light component, and a 3rd filter 6R which passes red light; and they are different in thickness from one another and selectively put in and out of the optical path 1 between the image forming lens 2 and photoelectric conversion part 5, one by one. Namely, the 1st filter 6B has maximum thickness, the 2nd filter 6G has intermediate thickness, and the 3rd filter 6R has minimum thickness, so that a difference in refractive index with wavelength is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device used for a color scanner such as a copying machine, a stencil printing machine and a facsimile.

[0002]

2. Description of the Related Art The color separation method in a color scanner is
The light source switching method, the 3-line image sensor method, and the color separation filter switching method can be classified into three methods. The color separation filter switching method is widely adopted in order to downsize the apparatus and reduce the price. For example, Japanese Patent Publication No. 4
As described in Japanese Patent Laid-Open No. 19533, there is one in which a plurality of color filters are provided so as to be able to advance and retract in the optical path from the subject to the photoconductor. In addition, Japanese Patent Laid-Open No. 2-217167
As described in the publication, an additive mixing type filter corresponding to the three primary colors of light and a subtractive mixing type filter corresponding to the three primary colors of dye and pigment are selectively advanced into the optical path. is there.

[0003]

Here, no matter which filter is used for color separation, it is necessary to provide an imaging lens 2 in the optical path 1 as shown in FIG.
Since the color scanner uses the entire visible light region, the imaging lens 2 has an influence of chromatic aberration. For example, when comparing the light 3 _R light 3 _B and red components of the blue component, an imaging lens than the light 3 _R component of wavelength longer red towards the light 3 _B components of wavelength shorter Blue The focus will be on a position close to 2. In order to remove the influence of such chromatic aberration, conventionally, the correction lens 4 is used as shown in FIG. 12 or the correction is performed by using a plurality of lenses, but the configuration of the imaging lens becomes complicated and the cost is increased. There is a problem that becomes high.

[0004]

The invention according to claim 1 is
A blue (B) or cyan (C) first filter, a green (G) or magenta (M) second filter,
A color separation filter portion is formed by a third filter of red (R) or yellow (Y), and the color separation filter portion is 0.1 mm to 4 m.
In the range of m, the thickness of the first filter was set to the maximum and the thickness of the third filter was set to the minimum.

Further, in the invention according to claim 2, a first filter of blue (B) or cyan (C), a second filter of green (G) or magenta (M), and red (R) or A color separation filter portion is formed by the third filter of yellow (Y), the refractive index of the first filter is 1.7 or more, the refractive index of the second filter is 1.55 to 1.7, The refractive index of the third filter was set to 1.55 or less.

Further, in the invention according to claim 3, the filters of the respective colors of the color separation filter portion are provided so as to be able to advance and retreat with respect to the optical path, and the image forming lens and the photoelectric conversion portion are formed depending on the type of the filter advancing into the optical path. An optical path length changing means for changing the optical path length is provided.

[0007]

According to the first aspect of the invention, since the chromatic aberration can be corrected by changing the thickness of the first, second and third filters, the structure of the lens system can be simplified.

According to the second aspect of the present invention, since the chromatic aberration can be corrected by changing the refractive index of the first, second and third filters, the structure of the lens system can be simplified.

According to the third aspect of the present invention, since the chromatic aberration can be corrected by changing the optical path length between the imaging lens and the photoelectric conversion section according to the type of the filter that advances into the optical path, the structure of the lens system is changed. It can be simplified.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the invention described in claim 1 will be described with reference to FIGS. An imaging lens 2 is provided in an optical path 1 from a document (not shown) to a photoelectric conversion unit (CCD image sensor) 5. Reference numeral 6 denotes a color separation filter unit. The color separation filter unit 6 includes a first filter 6 _B that transmits light of a blue (B) component and a second filter 6 _G that transmits light of a green (G) component. And a third filter 6 _R that allows light of the red (R) component to pass therethrough. The first, second, and third filters 6 _B , 6 _G , and 6 _R are characterized by different thicknesses, respectively, and are selectively provided one by one between the imaging lens 2 and the photoelectric conversion unit 5. Is to be advanced into the optical path 1 of.

Here, as shown in FIG. 2, for example, if the first filter 6 _B is advanced into the optical path 1, only the light 3 _B of the blue (B) component passes, and the third filter 6 _R passes.
If is made to enter the optical path 1, only the light 3 _R of the red (R) component passes. As shown in FIG. 2, if the first filter 6 _B and the third filter 6 _R have exactly the same thickness, the light 3 _B of the blue (B) component is red due to the difference in the refractive index depending on the wavelength. The light is focused on a position closer to the imaging lens 2 than the light 3 _R of the component (R). That is, the image plane of the image information of the blue (B) component that is desired to be input to the photoelectric conversion unit 5 appears on the imaging lens 2 side rather than the image plane of the image information of the red (R) component. This is because the light 3 _B of the blue (B) component has a larger refractive index depending on the wavelength than the light 3 _R of the red (R) component.

Therefore, in this embodiment, the thickness of the first filter 6 _B is maximized, the thickness of the second filter 6 _G is set to the second thickness, and the thickness of the third filter 6 _R is set. Was set as the minimum.

With such a structure, when an image of the red (R) component is obtained, as shown in FIG.
The third filter 6 _R is advanced into the optical path 1. As a result, the light 3 _B of the blue (B) component and the light of other components such as the light 3 _B do not pass, but only the light 3 _R of the red (R) component passes. When obtaining the image of the blue (B) component, the first filter 6 _B is advanced into the optical path 1 as shown in FIG. As a result, light of other components such as the light 3 _R of the component of red (R) does not pass, but only light 3 _B of the component of blue (B) passes. In FIG. 3, red (R) and blue (B), which have the largest chromatic aberration, are compared, but in order to obtain an image of the green (G) component, the second filter 6 _G is advanced into the optical path 1.

In this case, blue (B) and green (G)
And red, but (R) imaging lens 2 and a filter 6 due to a difference in wavelengths light component with _B, 6 _G, the refractive index with respect to 6 _R are different, the filter 6 according to a difference in the refractive index _B, 6 _The focal points can be made equal with a very simple structure in which the thicknesses of _G and 6 _R are set.

Here, when the imaging lens 2 having a focal length of 43 mm made of a material of BK7 is used, the difference in focal length between the red (R) component light and the blue (B) component light having the largest chromatic aberration. Is about 0.67 mm. This difference is corrected by the thickness of the filter. If the thickness of the third filter 6 _R is 1 mm, the second filter 6 _R
The thickness of _G is about 1.98 mm, and the thickness of the first filter 6 _B is about 2.95 mm. The filters 6 _B , 6 _G , and 6 _R are preferably thin in consideration of downsizing and thinning of the device, but in view of cost, if they are too thin, it becomes difficult to process.
From this point of view, the thickness of the third filter 6 _R is 0.
It is desirable to be 1 or more and 2 mm or less. Accordingly, the thickness of the second filter 6 _G is 0.9 mm or more and 3 mm or less, and the thickness of the first filter 6 _B is 2 mm or more and 4 mm or less, which are substantially desirable ranges.

Next, a second embodiment of the invention according to claim 1 will be described with reference to FIGS. 4 and 5. The same parts as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted (the same applies hereinafter).
7 is a color separation filter unit, and this color separation filter unit 7 is
First filter 7 _{C for} cyan (C) and magenta (M)
Of the second filter 7 _M for yellow and the third filter 7 _{Y for} yellow (Y). These first, second and third filters 7 _C , 7 _M and 7 _Y are selectively combined and advanced into the optical path 1 between the imaging lens 2 and the photoelectric conversion unit 5. is there.

In this case, in order to obtain an image of the blue (B) component, the first filter 7 _C and the second filter 7 _M
In order to move the and into the optical path 1 and obtain an image of the green (G) component, the first filter 7 _C and the third filter 7 _Y are advanced into the optical path 1, and the red (R) The second filter 7 _M and the third filter 7 _M are used to obtain the component images.
Advance _Y and into optical path 1.

The thickness of the filter is set such that the first filter 7 _C has the largest thickness, the second filter 7 _M has the next largest thickness, and the third filter 7 _Y has the smallest thickness. That is, the thickness of the filter for obtaining an image of the blue (B) component is the thickest in the total of the thickness of the first filter 7 _{C and} the thickness of the second filter 7 _M , and the thickness of the green (G) component is To obtain an image, the thickness of the first filter 7 _C and the third filter 7 _Y
And the thickness of the second filter 7 _{M and} the thickness of the third filter 7 _Y are the smallest when the image of the red (R) component is obtained.

In such a structure, when an image of the red (R) component is obtained, as shown in FIG.
The second filter 7 _M and the third filter 7 _Y are advanced into the optical path 1. As a result, the light 3 of the blue (B) component
Light of other components such as _B does not pass, but only light 3 _R of the component of red (R) passes. When obtaining the image of the blue (B) component, the first filter 7 _C and the second filter 7 _M are advanced into the optical path 1 as shown in FIG. 5B. As a result, light of other components such as the light 3 _R of the component of red (R) does not pass, but only light 3 _B of the component of blue (B) passes. In FIG. 5, red (R) and blue (B), which have the largest chromatic aberration, are compared, but in order to obtain an image of a green (G) component, the first filter 7 _C and the third filter 7 are used.
Advance _Y and into optical path 1.

In this case, blue (B) and green (G)
And although red (R) formed by the difference in wavelength each light component of the lens 2 and the filter 7 _C, 7 _M, 7 refractive index with respect to _Y are different, the filter 7 _C, 7 in accordance with the difference in refractive index _The focal points can be made equal with an extremely simple structure in which the thicknesses of _M and 7 _Y are set.

Also in this embodiment, when the image forming lens 2 having a focal length of 43 mm made of the material BK7 is used, the focal points of the red (R) component light and the blue (B) component light having the largest chromatic aberration are focused. The difference in distance is about 0.67 mm. This difference is corrected by the thickness of the filter, but if the thickness of the third filter 7 _Y is 1 mm,
The second filter 7 _{M has} a thickness of about 1.95 mm, and the first filter 7 _{C has} a thickness of about 2.92 mm. Also in this embodiment, the thickness of the third filter 7 _Y is preferably 0.1 or more and 2 mm or less from the viewpoints of downsizing, thinning, and cost of the device. Accordingly, the thickness of the second filter 7 _M is 1 mm or more and 3 mm or less, and the thickness of the first filter 7 _C is 2 mm or more and 4 mm or less, which are substantially desirable ranges.

Next, a first embodiment of the invention of claim 2 will be described with reference to FIGS. 6 and 7. Reference numeral 8 denotes a color separation filter unit. The color separation filter unit 8 includes a first filter 8 _B that transmits light of a blue (B) component and a second filter 8 _G that transmits light of a green (G) component. And a third filter 8 _R which allows light of the red (R) component to pass therethrough. These first, second, and third filters 8 _B , 8 _G , and 8 _R are characterized in that the respective materials have different refractive indexes, and selectively form the imaging lens 2 and the photoelectric conversion unit 5 one by one. It is to be advanced into the optical path 1 between.

As described in FIG. 2, due to the difference in the refractive index depending on the wavelength, the light 3 _B of the blue (B) component is closer to the imaging lens 2 than the light 3 _R of the red (R) component. Focus on. That is, the image plane of the image information of the blue (B) component that is desired to be input to the photoelectric conversion unit 5 appears on the imaging lens 2 side rather than the image plane of the image information of the red (R) component. This is because the light 3 _B of the blue (B) component has a larger refractive index depending on the wavelength than the light 3 _R of the red (R) component.

Therefore, in this embodiment, the refractive index of the first filter 8 _B is maximized, the refractive index of the second filter 8 _G is set to the second value, and the refractive index of the third filter 8 _R is set. Was set to the minimum value. The difference in refractive index is determined by the material.

In the structure as described above, when an image of the red (R) component is obtained, as shown in FIG.
The third filter 8 _R is advanced into the optical path 1. As a result, the light 3 _B of the blue (B) component and the light of other components such as the light 3 _B do not pass, but only the light 3 _R of the red (R) component passes. When obtaining an image of the blue (B) component, the first filter 8 _B is advanced into the optical path 1 as shown in FIG. 7B. As a result, light of other components such as the light 3 _R of the component of red (R) does not pass, but only light 3 _B of the component of blue (B) passes. In FIG. 7, red (R) and blue (B), which have the largest chromatic aberration, are compared, but in order to obtain an image of the green (G) component, the second filter 8 _G is advanced into the optical path 1.

In this case, blue (B) and green (G)
And although red (R) formed by the difference in wavelength each light component of the lens 2 and the filter 8 _B, the refractive index with respect to 8 _G, 8 _R are different, the filter 8 in accordance with the difference in refractive index _B, 8 _The focal points can be made equal with a very simple structure in which the refractive indices of _G and 8 _R are set.

Here, when the imaging lens 2 having a focal length of 43 mm made of the material BK7 is used, the difference in focal length between the red (R) component light and the blue (B) component light having the largest chromatic aberration. Is about 0.67 mm. This difference is corrected by the refractive index of the filter, but the refractive index of the third filter 8 _R is set to 1.51385 (material BK).
7), the refractive index of the second filter 8 _G is 1.66446.
Assuming that (material BaSF2), the refractive index of the first filter 8 _B is 1.78472 (material SF11), and the thickness of the third filter 8 _R is 1 mm, the thickness of the second filter 8 _G is approximately 1 mm. The thickness of the first filter 8 _B is 0.69 mm, and the thickness of the first filter 8 _B is approximately 2.3 mm. Therefore, the thickness of the filter can be made thinner than that of the embodiment of FIG. The range of the refractive index of each filter is _preferably 1.55 or less for the third filter 8 _R , 1.55 to 1.7 for the second filter 8 _G , and 1.7 or more for the first filter 8 _B.

To determine this refractive index, the material of the third filter 8 _R is FK5, K3, etc., the material of the second filter 8 _G is BaF4, SF2, etc., and the material of the first filter 8 _B. Is preferably LaSF2, SF6 or the like. When a plastic material is used, PMMA (acrylic) is used for the third filter 8 _R and the second filter 8 _R is used.
It is desirable to use PC (polycarbonate) for _G in terms of cost. Further, the range of the thickness of each filter when the refractive index of such a filter material is different is 0.1 mm to 2 mm for the third filter 8 _R and 0.8 mm to 2. mm for the second filter 8 _G. 6 mm, first filter 8
_B is preferably 1.5 to 3.1 mm.

Further, a second embodiment of the invention according to claim 2 will be described with reference to FIGS. 8 and 9. Reference numeral 9 is a color separation filter unit. The color separation filter unit 9 includes a first filter 9 _{C for} cyan (C), a second filter 9 _{M for} magenta (M), and a third filter 9 for yellow (Y).
_{And Y} , each of which has a different refractive index. The refractive index of the filter is the first filter 9 _C
Is the largest, the second filter 9 _M is the second largest, and the third filter 9 _Y is the smallest.

With such a structure, when an image of the red (R) component is obtained, as shown in FIG. 9 (a),
The second filter 9 _M and the third filter 9 _Y are advanced into the optical path 1. As a result, the light 3 of the blue (B) component
Light of other components such as _B does not pass, but only light 3 _R of the component of red (R) passes. When obtaining an image of the blue (B) component, as shown in FIG. 9B, the first filter 9 _C and the second filter 9 _M are advanced into the optical path 1. As a result, light of other components such as the light 3 _R of the component of red (R) does not pass, but only light 3 _B of the component of blue (B) passes. In FIG. 9, red (R) and blue (B), which have the largest chromatic aberration, are compared, but in order to obtain an image of the green (G) component, the first filter 9 _C and the third filter 9
Advance _Y and into optical path 1.

As shown in FIG. 9A, when an image of the red (R) component is obtained, the light passes through the second filter 9 _M having the medium refractive index and then the third filter having a small refractive index. Since the light passes through the filter 9 _Y , the focal length is in the direction of contraction. On the other hand, as shown in FIG. 9B, when a blue (b) image is obtained, the light is largely refracted when passing through the first filter 9 _C having the largest refractive index, and then the medium level is obtained. Since the light passes through the second filter 9 _M having a refractive index of, the focal length is in the extending direction. Although not shown, when obtaining an image of a green (G) component, light passes through the first filter 9 _C having a large refractive index and then the third filter 9 _Y having a small refractive index.
, The focal length is intermediate between the case where a red (R) image is obtained and the case where a blue (B) image is obtained. Therefore, chromatic aberration can be corrected with a simple structure by optimally setting the refractive index of the material of the filters 9 _C , 9 _M , and 9 _Y.

For example, also in this case, when the imaging lens 2 having a focal length of 43 mm made of the material BK7 is used, the red (R) component light and the blue (B) component, which have the largest chromatic aberration, are used.
The difference in focal length from the light of the component is about 0.67 mm.
This difference is corrected by the refractive index of the filter. The refractive index of the third filter 9 _Y is 1.51385 (material BK7), and the refractive index of the second filter 9 _M is 1.664.
46 (material BaSF2), the refractive index of the first filter 9 _C is 1.78472 (material SF11), and the thickness of the third filter 9 _Y is 1 mm, the thickness of the second filter 9 _M is about 1.5 mm, the thickness of the first filter 9 _C is about 2
mm. Therefore, the thickness of the filters 9 _C , 9 _M and 9 _Y can be made thinner than in the embodiment of FIG. Range of the refractive index of each filter 9 _C, 9 _M, 9 _Y, the third of the filter 9 _Y is 1.55 or less, a second filter 9 _M 1.5
5 to 1.7 and the first filter 9 _C is preferably 1.7 or more.

To determine this refractive index, the material of the third filter 9 _Y is FK5, K3, etc., the material of the second filter 9 _M is BaF4, SF2, etc., and the material of the first filter 9 _C. Is preferably LaSF2, SF6 or the like. When a plastic material is used, PMMA (acrylic) is used for the third filter 9 _Y and the second filter 9 _Y is used.
It is desirable to use PC (polycarbonate) for _M in terms of cost. In addition, such filters 9 _C , 9
Each filter 9 _C when the refractive index of the material of _M and 9 _Y is different,
9 _M, 9 thickness in the range of _Y is 0 in the third filter 9 _Y.
1 mm to 2 mm, 0.7 mm with second filter 9 _M
To 2.4 mm, and the first filter 9 _C preferably 1.4 to 2.6 mm.

Furthermore, an embodiment of the invention of claim 3 is shown in FIG.
It shows in 0. The present embodiment is characterized in that the difference in focal length due to the difference in wavelength of light is corrected by moving the photoelectric conversion unit on the optical axis according to the filter used.
The color separation filter unit 10 of the present embodiment includes a first filter 10 _B that transmits light of a blue (B) component and a green (G) filter.
The second filter 10 _G that passes the light of the component of _R and the third filter 10 _R that passes the light of the component of red (R). These filters 10 _B , 10 _G , and 10 _R have the same thickness and the same refractive index and are selectively advanced one by one into the optical path 1. Mobile stand 11 that holds the photoelectric conversion unit 5
Is held by the guide 12 so as to be movable in the optical path length direction,
It is biased by the spring 13 in a direction away from the imaging lens 2.

Therefore, the arm 14 as the optical path length changing means is held rotatably around the support shaft 15. Projections 16 and 17 are formed at one end of the arm 14 to interfere with the first filter 10 _B and the second filter 10 _G when they advance into the optical path 1, and at the other end, the movable table 1
An abutting portion 18 that abuts the end face of 2 is formed. Although this arm 14 receives the pressure of the spring 13 via the movable table 12, it is normally provided with a stopper not shown in FIG.
It is stable in the position shown in. The protrusion 16 is the protrusion 1.
It projects more than 7 toward the optical axis of the imaging lens 2.

In such a structure, when the filter 10 _B is advanced into the optical path 1 to obtain a blue (B) image, the arm 14 is supported by the arm 14 due to the interference between the protrusion 16 and the filter 10 _B. A large amount of clockwise rotation is made around 15 and the abutment portion 18 presses the movable table 12. As a result, the optical path length between the imaging lens 2 and the photoelectric conversion unit 5 becomes the shortest. When the filter 10 _G is advanced into the optical path 1 to obtain a green (G) image, the arm 14 rotates clockwise around the support shaft 15 due to the interference between the protrusion 17 and the filter 10 _G. Then, the contact table 18 presses the movable table 12, but the projection 17 has a small projection amount, and therefore the optical path length between the imaging lens 2 and the photoelectric conversion section 5 is a blue (B) image. It becomes short after. When the filter 10 _R is advanced into the optical path 1 in order to obtain a red (R) image, the arm 14 does not interfere with the filter 10 _R at all, so that the arm 14 remains stationary and the imaging lens 2 and photoelectric conversion are performed. The optical path length with the section 5 is the shortest.

Therefore, although the focal length becomes shorter as the light of the component having the shorter wavelength, the filters 10 _B , 10 _G ,
When 10 _R is selectively advanced into the optical path 1, the optical path length can be automatically and optimally changed by the operation of the arm 14, and therefore, a lens having a simple structure for imaging. The chromatic aberration can be corrected by using the system.

As described above, the method for changing the thickness of the filter, the method for changing the refractive index of the filter, and the method for changing the optical path length have been shown as examples for correcting the chromatic aberration, but these methods are independent. The method is not limited to the one used in, and a plurality of methods may be combined.

[0039]

According to the invention described in claim 1, the thickness of the first, second and third filters of the color separation filter section is changed in accordance with the difference in the wavelength of light, thereby forming the structure of the imaging lens system. It is possible to simplify the above and to correct chromatic aberration.

According to a second aspect of the invention, the structure of the imaging lens system is simplified by changing the refractive index of the first, second and third filters of the color separation filter section according to the difference in the wavelength of light. It has an effect that it is possible to correct the chromatic aberration as well as to reduce the color.

According to a third aspect of the present invention, the structure of the imaging lens system is provided by providing optical path length changing means for changing the optical path length between the imaging lens and the photoelectric conversion unit according to the type of filter that advances into the optical path. It is possible to simplify the above and to correct chromatic aberration.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration according to a first embodiment of the invention described in claim 1.

FIG. 2 is an explanatory diagram showing a difference in image forming position of light having different wavelengths when the thickness and the refractive index of the filter are the same.

FIG. 3 is an explanatory diagram showing image forming positions of light having different wavelengths when the thickness of the filter is changed.

FIG. 4 is an explanatory diagram showing a configuration according to a second embodiment of the invention according to claim 1;

FIG. 5 is an explanatory diagram showing image formation positions of lights having different wavelengths when the thickness of the filter is changed.

FIG. 6 is an explanatory diagram showing a configuration according to a first embodiment of the invention as set forth in claim 2;

FIG. 7 is an explanatory diagram showing image formation positions of light having different wavelengths when the refractive index of the filter is changed.

FIG. 8 is an explanatory diagram showing a configuration according to a second embodiment of the invention as set forth in claim 2;

FIG. 9 is an explanatory diagram showing image formation positions of lights having different wavelengths when the refractive index of the filter is changed.

FIG. 10 is an explanatory diagram showing a configuration according to an embodiment of the invention as set forth in claim 3;

FIG. 11 is an explanatory diagram showing a difference in image forming positions of lights having different wavelengths.

FIG. 12 is an explanatory diagram showing a conventional structure for correcting a difference in image forming position of light having different wavelengths.

[Explanation of symbols]

1 Optical Path 5 Photoelectric Conversion Section 6 Color Separation Filter Section 6 _B First Filter 6 _G Second Filter 6 _R Third Filter 7 Color Separation Filter Section 7 _C First Filter 7 _M Second Filter 7 _Y Third Filter 8 color separation filter section 8 _B first filter 8 _G second filter 8 _R third filter 9 color separation filter section 9 _C first filter 9 _M second filter 9 _Y third filter 10 colors Decomposition filter unit 10 _B filter 10 _G filter 10 _R filter 14 Optical path length changing means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Watanabe 10 Ricoh Applied Electronic Research Laboratories, Inc., 5th place, Yukata, Takadate, Kumanodou, Natori City, Miyagi Prefecture

Claims (3)

[Claims] 1. A light source for illuminating a document with illumination light, and a color separation filter section for separating reflected light from the document into primary colors.
In a color scanner including a photoelectric conversion unit that converts decomposed light into an electric signal, a first filter of blue (B) or cyan (C) and green (G) or magenta (M)
Second filter with red (R) or yellow (Y)
The third color filter is used to form the color separation filter section, and the thickness of the first filter is set to the maximum and the thickness of the third filter is set to the minimum in the range of 0.1 mm to 4 mm. Characteristic image input device. 2. A light source for illuminating a document with illumination light, and a color separation filter section for separating reflected light from the document into primary colors.
In a color scanner including a photoelectric conversion unit that converts decomposed light into an electric signal, a first filter of blue (B) or cyan (C) and green (G) or magenta (M)
Second filter with red (R) or yellow (Y)
The third color filter is used to form the color separation filter section, the first filter has a refractive index of 1.7 or more, and the second filter has a refractive index of 1.55 to 1.7. An image input device in which the refractive index of the third filter is set to 1.55 or less. 3. A light source for illuminating a document with illumination light, and a color separation filter section for separating reflected light from the document into primary colors.
In a color scanner including a photoelectric conversion unit that converts separated light into an electric signal, a filter for each color of the color separation filter unit is provided to advance and retreat with respect to an optical path, depending on the type of the filter that advances into the optical path. An image input device comprising optical path length changing means for changing an optical path length between the imaging lens and the photoelectric conversion unit.