JPS62161A - Color original reader - Google Patents

Abstract

PURPOSE:To attain excellent color reading with a simple construction by setting each filter to an arc shape and the shape of an opening part between filters to a shading correction shape. CONSTITUTION:Respective filters 19a-19c are made in arc shapes, coaxially arranged with a rotating spindle 20 as a center and are generally made in approximately a cylindrical shape. The ends of the filters 19a-19c are bent in a drumlike shape so as to form, and the shapes of the opening parts 22a-22c formed between the filters 19a-19c are set in shading correction shapes. Namely the opening parts 22a-22c are set so that their centers are narrow in width sand become gradually wider as the width go to both sides. Thus it is unnecessary that an exclusively used shading correction plate is separately installed, and the excellent color reading can be possible at a moderate cost with the simple construction.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a color document reading device such as a facsimile machine or a digital scanner.

BACKGROUND OF THE INVENTION Conventionally, there have been various color reading systems for this type of color document reading apparatus, but most of them use a tr-shaped tip light source as a light source. FIG. 3 schematically shows a color scanner using such a band-shaped light source. First, the original 1 is transported by transport rollers 2 and 3 to a reading position between a target glass 4 and a pressure plate 5. As shown in FIG. This document 1 is exposed and illuminated by a band-shaped light source, for example, a fluorescent lamp 6. and,
Reflected light from the original 1 is imaged on a photoelectric conversion element, for example, a CGDIO, through an imaging optical system 9 including a mirror 7 and a lens 8, and photoelectrically converted to read the original image. Here, 11 is a circuit board to which the CCD10 is attached, and 12 is a base for the lens 8. A filter group 13 is provided in the optical path of the imaging optical system 9, here in front of the lens 8. This filter group 13 uses a plurality of filters, for example, three filters 14a to 14c, in order to decompose the reflected light from the original 1. Here, these filters 14a to 14c are arranged and fixedly supported in a substantially equilateral triangular prism shape with respect to the side plate 15, and there is a filter 14a between each filter 14a to 140.
Openings 16a to 16c are formed opposite to 14c. Further, a rotating shaft 17 is formed on the outside of the side plate 15.
It is connected to a drive motor (not shown). This results in
By controlling the drive motor to rotate the filter group 13, one of the filters 14a to 14c is positioned in the optical path, and the document 1 that has passed through the filter 14a to 14C is
The reflected light is focused by the lens 8 and imaged on the CGDIO. Here, the filter group 13 is CGDIO
The rotation is controlled by a drive motor in accordance with the reading timing.

When considering the operation of the filter group 13, it is necessary to accurately maintain the surface angle of each filter 14a to 14c with respect to the optical axis (reading line) φ. In other words, if the filter 14a is tilted with respect to the optical axis φ as shown in FIG. 4, it will deviate from the reading line of the CCD 10 as shown by the dashed line, making it impossible to perform color separation using the filter 14a. This is because Therefore, in the conventional method, the attitude control of the filter group 13 is required to be highly accurate, resulting in an expensive product.

Furthermore, in the case of such a strip-shaped light source, the illuminance at both ends is lower than that at the center. Therefore, in order to prevent a decrease in illuminance at the ends, shading correction is generally performed using a shading correction plate. Here, the color reading device shown in FIG. 3 uses a filter group 13 for color reading, and these filter groups 13 and shading correction plates are each installed separately. This results in an increase in the size and complexity of the device, and further increases in cost.

Purpose The present invention has been made in view of the above points, and an object of the present invention is to provide a color document reading device in which the posture control of a filter group is extremely simple, and in which a shading correction function can be easily ensured. do.

Structure In order to achieve the above object, the present invention provides a filter group in which a plurality of arc-shaped filters are arranged in a substantially cylindrical shape through openings, and are rotatable so that any one of the filters can be selected. It is installed in the optical path of the imaging optical system that images the light reflected from the original onto the light receiving section, and the end of each filter in this filter group is formed into a curved shape, and the opening between each filter is shaped into a shading correction shape. It is characterized by this.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 and 2. The overall configuration as a color scanner is the third.
Since it is the same as the figure, it will be omitted (the same reference numerals will be used in the description when necessary).

In this embodiment, the filter group 18 is basically the same as the filter group 13, and includes a plurality of filters, for example, three filters 19a to 19c, for color-separating the reflected light from the document, and has a rotation shaft 20. Although the filters 198 to 19c are fixedly supported between the side plates 21, each of the filters 198 to 19c is arc-shaped.
They are arranged concentrically around the rotating shaft 2o, and have a generally cylindrical shape as a whole. In addition, in this embodiment, in such a filter group 18, each filter 19a to
The end of 19c is formed into a drum-shaped curved shape,
Each opening 22 formed between each filter 19a to 19c
The shapes of a to 22c are made into shading correction shapes. In other words, each of the openings 22a to 22c has a curved shape that is narrow at the center and widens toward both ends. Note that R, G, and B are used for each of the filters 19a to 19c in the case of full-color reading, but filters in other colors may be used for special purposes.

According to such a configuration, first of all, when considering attitude control of the filter group 18, each of the filters 19a to 19c has an arc shape centered on the rotation axis 20, and even if the stop position is slightly shifted, Any filters 198 to 19c selected are orthogonal to the optical axis φ,
The light after passing through these filters 19a to 19c does not deviate from the optical axis φ, and the color separation signals are reliably read by the CCD 10.

Further, when the reflected light from the original 1 passes through the openings 22a to 22c in the filter group 18, the light in the center is narrowed down by the shading correction shape, and the reflected light from the original 1 is generated by an apparently uniform light source. CC in the same state as
The image is formed on D10.

More specifically, for example, when the filter 19a is used, filters 1 other than this filter 19a
Shading correction is performed by the opening 22a formed by 9b and 19c.

According to this embodiment, each of the filters 19a to 19c of the filter group 18 has an arc shape and is arranged on concentric circles, which facilitates orthogonality to the optical axis φ.
The filter 19a of the filter group 18 provided for color reading simplifies the attitude control of the filter group 18 and enables reliable color reading at low cost.
Since shading correction can be performed by making the openings 22a to 22c into shading correction shapes using the openings 22a to 22c, there is no need to separately provide a dedicated shading correction plate. This makes it possible to perform good color reading with an inexpensive and simple structure.

Effects In the present invention, as described above, each filter in the filter group is formed into an arc shape, so that it is easy to achieve orthogonality between each filter and the optical axis when the filter group is rotated.
The attitude of the filter group can be controlled extremely easily.
It is possible to perform reliable color reading at a low cost of 1 or more, and since the shape of the opening between the filters is a shading correction shape, there is no need to provide a dedicated shading correction plate separately from the filter group. , it is possible to perform good color reading with an inexpensive and simple structure.

[Brief explanation of drawings]

FIG. 1 is a side view of a filter group showing one embodiment of the present invention;
FIG. 2 is a front view thereof, FIG. 3 is a side view of the entire color scanner showing a conventional example, and FIG. 4 is a side view of its filter group. 1... Original, 9... Imaging optical system, 1'o... CC
D (light receiving section), 18...filter group, 19a to 19
c...Filter, 22a-22c...Aperture amount Applicant Ricoh Co., Ltd. -3"times" Z-Wa

Claims (1)

[Claims] A plurality of arc-shaped filters are arranged in a substantially cylindrical shape through openings, and a filter group that is rotatable so that any one of the filters can be selected forms an image of reflected light from the original on a light receiving section. 1. A color original reading device, which is provided in an optical path of an imaging optical system, and wherein an end portion of each filter of the filter group is formed into a curved shape, and the opening between each filter is formed into a shading correction shape.