JPH0396062A - Color information input device - Google Patents

Abstract

PURPOSE:To fetch correct color input information without losing color balance among each color by forming the light receiving plane of each photoelectric conversion element in shape so that the change of an element area in a main scan direction can be kept constant in each photoelectric conversion element group. CONSTITUTION:The shape of the light receiving plane of the photoelectric conversion element of each color of R, G, and B in the photoelectric conversion element group is divided and formed in stripe shape with equal width in a direction of 45 deg. against the main scan direction M(arranging direction) and a subscan direction(scanning direction) S. The output of each color goes to R=R1+R2+R3, G=G1+G2, and B=B1+B2, respectively, and the change of the area of the light receiving plane of each color is expressed in the change of length in the subscan direction assuming the main scan direction as an axis of obscissa in one group, and R, G, and B is kept constant, respectively. Therefore, the input intensity of each color in each group of (n-1), (n), and (n+1) can be set uniformly among each color by receiving light with the light intensity of a black and white pattern A, which enables precise input information to be obtained.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a color information input device.

2. Description of the Related Art As an image sensor used in color copying machines, color facsimile machines, etc., a CCD linear image sensor is generally used, which reads image contents line by line while scanning the surface of a document.

Here, the image content on the document surface is imaged onto a linear light receiving section by a 1-magnification imaging element such as a lens or a roof mirror lens array. The light-receiving section is configured as a collection of minute groups (each responsible for reading three pixels) arranged along a straight line, and usually performs photoelectric conversion corresponding to the three primary colors of green G, blue B, and red R. It is determined by the element. The image information photoelectrically converted row by row is sequentially converted for each group and output to an external circuit.

FIG. 6(b) shows an example of the configuration of a light receiving section of a conventional color image sensor (CCD linear image sensor).

That is, each photoelectric conversion element indicated by R, G, and B is set as one set.
(n-l) v ne (n + 1) v~
It consists of photoelectric conversion element groups as shown in , which are regularly arranged in the main scanning direction M. A photodiode is generally used as a photoelectric conversion element.

Problems to be Solved by the Invention With such a color imaging device, extremely satisfactory results can be obtained if the illuminance of the imaged document can be considered to be uniform within the light-receiving surface of each group. However, if the image density on the document surface changes, the illuminance of the image formed on the image sensor light receiving section will change correspondingly, and it can no longer be considered constant within each group, resulting in the following problems. A point occurs.

First, as shown in FIG. 6(a), consider a case in which an image on a document is scanned and read in the vicinity of a black and white area by a color image pickup device as shown in FIG. 6(b).

For example, when a transparent original is brought into close contact with a color image sensor and irradiated from above, the black and white two-division pattern A on the original is irradiated as pattern A onto the color image sensor. Here, if the black level is represented by 0 and the white level is represented by lO, the output of each photoelectric conversion element in each group is as shown in Table 1.

In addition, when a reflective original is illuminated and the reflected light is imaged on a color image sensor using an imaging optical system such as a lens, the black and white two-split pattern A on the original has a spatial frequency that is equal to the resolution MTF of the lens. As the value increases, it approaches 1, so an image is formed on the color image sensor in a pattern as shown by B in FIG. 6(a). In this case, the output of each photoelectric conversion element in each group is as shown in Table 2.

On the other hand, in a digital copying machine, information on any one point is required as color signals of the three primary colors R, G, and B.

In this case, in the example of a black and white pattern, R, G of each group
, B must have equal amounts of R, G, and B.

If the amounts are not equal, the data will be colored gray or black, i.e.
This is because the data will be input as color-balanced data.

However, as shown in Tables 1 and 2, R, G, B
have different outputs, and in the case of Table 1, 1
00%, and in the case of Table 2, the color balance is out of order by up to 65%.

Even if the shape of each R, G, and B light-receiving surface is oblique as shown in Figure 7(b), the image is formed in black and white pattern B with the light intensity as shown in Figure 7(a). In this case, the output of each photoelectric conversion element in each group will be as shown in Table 3, and the color balance will be out of order as in the above case.

Means for Solving the Problems In a color information input device in which photoelectric conversion element groups consisting of a plurality of types of photoelectric conversion elements that operate in response to light of different wavelength pairs are arranged regularly in at least one-dimensional main scanning direction. In the invention described in claim 1, the light-receiving surface of each photoelectric conversion element is formed in a shape such that the element area change in the main scanning direction is constant within each photoelectric conversion element group, and in addition to this,
In the invention according to claim 2, the light receiving surface of each photoelectric conversion element is
The element area change in the sub-scanning direction was shaped to be constant within each photoelectric conversion element group.

No matter where in the element the part where the density of the working original has changed passes, the light-receiving surface area of the photoelectric conversion element of each color in the light'a conversion element group is constant in the main scanning direction. The input intensity between the two is the same at any position in the main scanning direction, so the color balance between each color is not disturbed, and accurate color information can be captured.

In this case, if the change in the light-receiving surface area is made constant in the sub-scanning direction, no electrical correction is required.
Reading without deviation of color balance is possible at any position in the sub-scanning direction.

Embodiment A first embodiment of the present invention will be explained based on FIGS. 1 to 3.6 First, FIG. 1(a) shows photoelectric conversion of each color of R, G, and B in one photoelectric conversion element group. This shows the shape of the light-receiving surface of the element, which is formed by dividing into equal-width stripes in the direction of 45 degrees with respect to the main scanning direction (array direction) M and the sub-scanning direction (scanning direction) S. Although the colors can be arranged in any order, in this embodiment, the colors are arranged in the order of R, G, and B.

Here, the output of each color is R = R, + R, +
R,, G=G, 10G,, B=B, +B, and the change in the light-receiving surface area of each color is, if the main scanning direction is taken as the horizontal axis within l group, then the sub-scanning direction is Although it is expressed as a change in length in the direction, each of R, G, and B remains constant as shown in FIG. 1(b). The horizontal axis is the sub-scanning direction, and the length changes for each color R, G, and B in the main scanning direction are also shown in Figure 1 (
It is constant as in case b).

In Fig. 1(b), the constant area change of each color R, G, and B is shown by the same straight line, but depending on the light receiving sensitivity of R, G, and B and the processing of the input signal, the same straight line ( That is,
They do not have to be the same width).

Such photoelectric conversion element groups are shown in Figures 2(b) and 3.
A large number of them are arranged in the main scanning direction M, as shown by ~(n-1), n, (n+1)r~ in FIG. 2(b).

According to such a configuration, for example, the black and white pattern as described above is closely attached to the color image sensor, as shown in FIG. 2(a).
If light is received with the light intensity of black and white pattern A as shown in Table 4, the input intensity of each color in each group of (n-1), n, and (n+1) is as shown in Table 4, and the power is As shown in Table 5, although the intensity of the light changes somewhat depending on the MTF of the imaging system, the color balance will not be disrupted.

It is uniform between each color and accurate input information can be obtained.

This means that even if the image forming optical system distorts the black and white pattern B, the resolution MTF corresponding to the sensor density is
If the imaging system has the following, the correct color balance between each color is maintained as in the case of Table 5 without affecting the light intensity of adjacent groups.

Furthermore, as shown in FIG. 3(a), the black and white pattern B is 1
Regardless of where the black and white pattern appears in the sub-scanning direction, the appearance of each color in this case is the same no matter where in the group it passes (for example, between groups as shown).

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, within l pixels (within one group),
The light-receiving surfaces of the photoelectric conversion elements for each color of R, G, and B are arranged in the form of equal-width stripes in the sub-scanning direction, so that only the change in area in the main-scanning direction is constant. 300dpi
In the case of 84 pm, in the case of 400 dpi, the positive force form of about 63 pm forms l group 1.
This is the size of a pixel.

In the case of this embodiment, the effect of maintaining color balance appears only in the main scanning direction and not in the sub-scanning direction, but in the sub-scanning direction, the input information of the light intensity of each color is adjusted according to the speed of the scanner traveling body. This can be dealt with by electrical correction such as delayed capture.

As shown in FIG. 5, the light-receiving areas of the photoelectric conversion elements for each color of R, G, and B are arranged in the sub-scanning direction as stripes with different widths depending on the light-receiving sensitivity of each color. Alternatively, only the area change may be made constant.

Effects of the Invention In the present invention, as described above, the light-receiving surface of each color photoelectric conversion element in a photoelectric conversion element group is shaped so that the change in element area in the main scanning direction is constant. Regardless of where the photoelectric conversion element passes through the element, the input intensity between the photoelectric conversion elements of each color is the same at any position in the main scanning direction, so the color balance between each color is not disturbed, and accurate color information can be obtained. In particular, since the change in the light-receiving surface area remains constant even in the sub-scanning direction, color correction can be performed at any position in the sub-scanning direction without the need for electrical correction. It is possible to perform reading without shifting the balance.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the light receiving surface shape and area change characteristics showing the first embodiment of the present invention, Fig. 2 is an explanatory diagram showing the light intensity and light receiving part configuration of a black and white pattern, and Fig. 3 is an explanatory diagram showing the black and white pattern. FIG. 4 is an explanatory diagram showing the light intensity and configuration of the light-receiving section, FIG. 4 is an explanatory diagram of the shape of the light-receiving image showing the second embodiment of the present invention, FIG. FIG. 7 is an explanatory diagram showing an example of the light intensity and the configuration of the light receiving section of a conventional black and white pattern, and FIG. 7 is an explanatory diagram showing an example of the light intensity and the configuration of the light receiving section of a different conventional black and white pattern. R, G, B... photoelectric conversion element, n-1, n, n+l.
...Photoelectric conversion element group 1 7 times

Claims (1)

[Claims] 1. A color information input device in which a photoelectric conversion element group consisting of a plurality of types of photoelectric conversion elements that operate in response to light of mutually different wavelength pairs is regularly arranged in at least one-dimensional main scanning direction. A color information input device characterized in that the light-receiving surface of each photoelectric conversion element is formed in a shape such that a change in element area in the main scanning direction is constant within each photoelectric conversion element group. 2. The color information input device according to claim 1, wherein the light-receiving surface of each photoelectric conversion element is formed in a shape such that a change in element area in the sub-scanning direction is constant within each photoelectric conversion element group.