JPH09172522A - Image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure of an image forming lens system and to correct color aberration. SOLUTION: A color separate filter section 10 is arranged toward an original side of an image forming lens 2 and filters 10B, 10G, 10R of each color of the color separation filter section 10 are provided independently movably freely forwards and backwards in a direction orthogonal to an optical path 1. Then the device has a moving body 14 in interlocking with the motion of the filters 10B, 10G, 10R, a spring 13 energizing a photoelectric conversion section 5 to butt-contact with the moving body 14 and an optical path length revision means to change the optical path length between the image forming lens 2 and the photoelectric conversion section 5 by moving the photoelectric conversion section 5 in response to the motion of the moving body 14.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a copying machine,
The present invention relates to an image input device used for a color scanner such as a stencil printer 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 retreat in an optical path from a subject to a photoconductor. In addition, Japanese Patent Laid-Open No. 2-217167
As described in the publication, an additive mixture type filter corresponding to the three primary colors of light and a subtractive mixture type filter corresponding to the three primary colors of dye and pigment are selectively advanced into the optical path. is there.

[0003]

No matter which filter is used for color separation, as shown in FIG.
Although it is necessary to provide the imaging lens 2 in the optical path 1, since the color scanner uses the visible light region entirely, 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. 3 or the correction is performed using a plurality of lenses.
There is a problem that the structure of the imaging lens becomes complicated and the cost becomes high.

[0004]

According to the present invention, a light source for illuminating an original with illumination light, an imaging lens for forming an image of reflected light from the original, and a color for separating the reflected light from the original into primary colors. In a color scanner including a separation filter unit and a photoelectric conversion unit that converts separated light into an electric signal, the color separation filter unit is arranged on the original side of the imaging lens, and each color of the color separation filter unit is arranged. Each of the filters is provided so as to independently advance and retreat in the direction orthogonal to the optical path, and the photoelectric conversion unit is biased so as to come into contact with the movable body that is interlocked with the movement of the filter that advances into the optical path. An optical path length changing unit having a spring and changing the optical path length between the imaging lens and the photoelectric conversion unit by moving the photoelectric conversion unit according to the movement of the movable body is provided. Therefore, since the chromatic aberration can be corrected by 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, the structure of the lens system can be simplified and the photoelectric conversion can be performed. Since the element is biased by the spring and pressed against the movable body, it can be moved with high accuracy and does not change with time.

[0005]

FIG. 1 shows an embodiment of the present invention. One embodiment of the present invention 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. Color Separation Filter Unit 10 of One Embodiment of the Present Invention
Is the first filter 10 that allows light of the blue (B) component to pass therethrough.
_B , a second filter 10 _G that allows light of a green (G) component to pass through, and a third filter 10 _R that allows light of a red (R) component to pass through. These filters 10 _B , 10
_G and 10 _R have the same thickness and refractive index, and are selectively advanced one by one into the optical path 1. The movable base 11 holding the photoelectric conversion unit 5 is held by a guide 12 so as to be movable in the optical path length direction, and a spring 13 forms an imaging lens 2
It is urged in a direction away from.

Thus, the arm 14 as a movable body is rotatably held around the support shaft 15. Projections 16 and 17 that interfere with the first filter 10 _B and the second filter 10 _G when they advance into the optical path 1 are formed at one end of the arm 14, and the movable table 11 is provided at the other end. An abutting portion 18 that abuts the end face of the. This arm 1
4 receives the pressure of the spring 13 via the moving base 11, but is normally stabilized at the position shown in FIG. 1 by a stopper (not shown). The projection 16 is projected more toward the optical axis of the imaging lens 2 than the projection 17. The movable table 11 holding the photoelectric conversion unit 5, the spring 13, and the arm 14 form an optical path length changing unit.

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 clockwise rotation is made around 15 and the movable table 11 is pressed by the contact portion 18. 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, although the moving table 11 is pressed by the contact portion 18, since the protrusion amount of the protrusion 17 is small, the optical path length between the imaging lens 2 and the photoelectric conversion portion 5 is a case where a blue (B) image is obtained. 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 a component having a shorter wavelength, the filters 10 _B , 10
_{When G} and 10 _R are 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 simple structure for image formation can be obtained. The chromatic aberration can be corrected by using the lens system of

[0009]

According to the present invention, since the chromatic aberration can be corrected by changing the optical path length between the imaging lens and the photoelectric conversion unit according to the type of the filter that advances into the optical path, the structure of the lens system is simplified. Since the photoelectric conversion element is biased by the spring and pressed against the movable body, the photoelectric conversion element can be moved with high accuracy, and there is an effect that there is no change with time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a difference between image forming positions of lights having different wavelengths.

FIG. 3 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 2 Imaging Lens 5 Photoelectric Converter 10 Color Separation Filter 10 _B Filter 10 _G Filter 10 _R Filter 13 Spring 14 Arm (Movable Body)

Front Page Continuation (72) Inventor Toshiaki Watanabe 10 Ricoh Applied Electronics Research Laboratories, Inc., 5th place, Yukata, Takadate, Kumanodou, Natori City, Miyagi Prefecture

Claims (1)

[Claims] 1. A light source for illuminating an original document with illumination light, an imaging lens for forming an image of reflected light from the original document, a color separation filter section for separating the reflected light from the original document into primary colors, and a separated light beam. In a color scanner including a photoelectric conversion unit for converting to an electric signal, the color separation filter unit is arranged on the original side of the imaging lens, and each color filter of the color separation filter unit is orthogonal to an optical path. The movable body is provided so as to independently advance and retreat in the direction, and has a movable body that interlocks with the movement of the filter that advances into the optical path, and a spring that urges the photoelectric conversion unit to contact the movable body. An image input device comprising: an optical path length changing unit that changes the optical path length between the imaging lens and the photoelectric conversion unit by moving the photoelectric conversion unit according to the movement of the body.