JPH02203666A - Color picture reader - Google Patents

Abstract

PURPOSE:To surely prevent deterioration in the picture quality of a red color at the time of reading a color image and to obtain a color picture with high picture quality without losing the color sensitivity of the red color by using a sharp cut filter so as to eliminate a signal only at the red area especially at a long wavelength side from a reflected light from an original and sending the result to a photodetector section. CONSTITUTION:A sharp cut filter deflecting a reflected light from an original 1 toward a photodetector section 4 is provided and the light toward the long wavelength, especially a signal in the red area is removed from the reflected light from the original 1 by the sharp cut filter 7 and the resulting signal is fed to the photodetector section 4. Thus, abnormal sensitivity of the sensor in the infrared region is prevented and the deterioration in the picture is prevented without losing the color component of the red color. Thus, the color picture is read with high picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image reading device used to read color images in color facsimile machines, color copying machines, and the like.

[Prior Art] Fig. 5 shows the configuration of a color image reading device shown in, for example, the proceedings of the 70th Anniversary National Conference of the Institute of Electronics, Information and Communication Engineers (1988) Nα1241r multi-chip contact type color image sensor unit. In the figure, 1 is an original on which a color image to be read is written, 2 is a transparent original table (glass etc.) on which this original 1 is placed, 3
4 is a fluorescent lamp (light source) that illuminates the original 1; 4 is a sensor board (light receiving unit) that reads a color image; 5 is a rod lens array that forms a color image of the original 1 on the sensor board 4;
Reference numeral 6 denotes an infrared cut filter disposed between the fluorescent lamp 3 and the document table 2.

Next, the operation will be explained. The original 1 placed on the yXX table 2 is illuminated by a fluorescent lamp 3, and a color image of the original 1 is formed by the rod lens array 5 onto the sensor substrate 4 as an erect, equal-magnification real image.

In addition, fluorescent lamp 3. Sensor board 4. Rod lens array 5
And the infrared cut filter 6 is integrated in the direction of arrow A (
Since the image information of the original 1 is sequentially converted into an electric signal for each scanning line (main scanning direction), the image information of the original 1 is sequentially converted to an electric signal for each scanning line (main scanning direction). Further, a plurality of color filters are arranged on the sensor substrate 4.

At this time, the light from the fluorescent lamp 3 is filtered through the infrared cut filter 6
Since the long wavelength side components of the light are removed and the light is irradiated onto the original 1, only the image in the visible range from the original 1 can be photoelectrically converted.

By the way, FIG. 6 is a graph showing the spectral characteristic curve of the color image sensor in the light receiving section (sensor board 4), and shows sensor outputs for yellow Y, green G, cyan C, and white W, respectively.

FIG. 7 shows the spectral transmission characteristics of the infrared cut filter 6.

Furthermore, the spectral characteristics of the conventional color image reading device shown in FIG. 5 are expressed as the product of the spectral characteristics of the color image sensor and the spectral characteristics of the infrared cut filter 6 shown in FIGS. 6 and 7. and each color Y, G.

A curve as shown in FIG. 8 is obtained for each C2W.

Next, calculation of RGB will be explained. If the output values for each color obtained through the color filter of each light receiving element on the sensor board 4 are Sv, Sy, Sg, and SC, then the following equation (
1), red (R), green (G).

Blue CB) is converted to a value.

The matrix of 3 rows and 4 columns in the above equation (1) is called a transformation matrix M.

[Problems to be Solved by the Invention] Since the conventional color image reading device is configured as described above, the output value obtained from the color image reading device having the spectral characteristics shown in FIG. 8 is (1). When converted into RGB values by the formula, the long wavelength side (600 to 700+m
) has low sensitivity, so the elements of the conversion matrix M that determine red color must be increased. So this is the red S
This poses a problem of worsening the /N ratio and leading to deterioration of image quality.

This invention was made to solve the above-mentioned problems, and provides a color image reading device that prevents the deterioration of images for reddish colors and makes it possible to read color images with higher image quality. The purpose is to obtain.

[Means for Solving the Problems] A color image reading device according to the present invention is provided with a sharp cut filter that deflects reflected light from a document toward a light receiving section.

[Function] In the color image reading device of the present invention, the reflected light from the original is sent to the light receiving section after signals only in the long wavelength region, particularly in the infrared region, are removed by the sharp cut filter.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

In Figure 1, as in the past, 1 is a document on which a color image to be read is written, 2 is a transparent document table (glass etc.) on which this document 1 is placed, and 3 is a fluorescent lamp that illuminates the document 1. (light source), 4 is a sensor substrate (light receiving section) having a plurality of color filters for reading a color image, and 5 is a rod lens array for forming a color image of the original 1 on the sensor substrate 4.

In this embodiment, the conventional infrared cut filter (see reference numeral 6 in FIG. 5) is omitted, and instead, a sharp cut filter 7 is provided that deflects the reflected light from the document 1 toward the sensor substrate 4. ing.

This sharp cut filter 7 has transmittance characteristics which will be described later with reference to FIG. Further, a rod lens array 5 is arranged between the sharp cut filter 7 and the sensor substrate 4.

Note that if the distance between the reflective surface of the original 1 and the sharp cut filter 7 is a, the distance between the sharp cut filter 7 and the rod lens array 5 is b, and the distance between the rod lens array 5 and the sensor board 4 is C, then c Each part is installed so that = a + b.

Next, the operation of the apparatus of this embodiment will be explained.

A document 1 placed on a document table 2 is illuminated by a fluorescent lamp 3 , and reflected light from the document 1 is deflected toward a sensor substrate 4 by a sharp cut filter 7 . Then, the light deflected by the sharp cut filter is imaged by the rod lens array 5 on the sensor substrate 4 as a real image with the same magnification. In addition, fluorescent lamp 3. Sensor board 4. The rod lens array 5 and the sharp cut filter 7 integrally move the original 1 and the original platen 2 in the direction of arrow A (sub-scanning direction).
Since the image information of the original 1 is sequentially converted into an electric signal for each scan M (main scanning direction),

Here, the sharp cut filter 7 transmits light on the long wavelength side, and by using it as a means of deflection, it can simultaneously transmit light in the infrared region and reflect light in the visible region. in.

A color image is sent to the sensor board 4.

Figure 2 is a graph showing the transmittance of the sharp cut filter in Figure 1.As is clear from this figure, the transmittance increases rapidly from around 700 m on the long wavelength side. By using this as a reflector, it is possible to transmit light in the infrared region and reflect only light in the visible region.

Therefore, FIG. 3 is a graph showing the spectral characteristics of the color image reading device in consideration of the transmittance of the sharp cut filter 7 shown in FIG. Accordingly, abnormal sensitivity of the sensor in the infrared region can be prevented, and image deterioration can be prevented without damaging red color components.

In the above embodiment, the sharp cut filter 7 used as a reflection plate was arranged between the rod lens array 5 and the sensor board 4, but as shown in FIG. 2) and the sharp cut filter 7 may be arranged. In this case as well, not only the same effects as in the above embodiment can be obtained, but also the effect that the dimensions in the sub-scanning direction A can be further reduced and the apparatus can be made more compact can also be obtained.

Further, in the above embodiment, the reflected light from the document 1 is configured to be reflected in the right angle direction by the sharp cut filter 7, but the reflected light may be reflected in a direction other than the right angle. In the example, the rod lens array 5 is used as the imaging system, but the invention is not limited to this, and other systems having an imaging function, such as a reduction lens, may also be used. Further, in the above embodiment, the fluorescent lamp 3 is used as a light source, but other lamps capable of illuminating the original 1, such as a tungsten lamp, may also be used.

[Effects of the Invention] As described above, according to the present invention, the reflected light from the original is configured to be sent to the light receiving section by removing signals only in the long wavelength side, especially in the infrared region, using a sharp cut filter. This has the effect of reliably preventing deterioration of the image quality of red colors when reading a color image without impairing red color sensitivity, and obtaining a high quality color image.

[Brief explanation of the drawing]

FIG. 19 is a configuration diagram showing a color image reading device according to an embodiment of the present invention, FIG. 2 is a graph showing transmittance characteristics of the sharp cut filter of this embodiment, and FIG. 3 is a spectral characteristic of the device of this embodiment. 4 is a block diagram showing a color image reading device according to another embodiment of the present invention, FIG. 5 is a block diagram showing a conventional color image reading device, and FIG. 6 is a block diagram showing a conventional color image reading device. Graph showing spectral characteristics, 7th
The figure is a graph showing the spectral transmission characteristics of a conventional infrared cut filter, and FIG. 8 is a graph showing the spectral characteristics of a conventional device. In the figure, 1 - original, 3 - fluorescent lamp (light source), 4 - sensor board (light receiving section), 7 - sharp cut filter. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a color image reading device comprising a light source that illuminates a document, and a light receiving section having a plurality of color filters for receiving reflected light from the document illuminated by the light source and reading a color image written on the document. . A color image reading device, further comprising a sharp cut filter that deflects reflected light from the document toward the light receiving section.