JPH0736594B2 - Imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a color sensor chip having a configuration in which a plurality of photoelectric conversion elements are arranged in a line and a three-color stripe filter is on-chip on the photoelectric conversion elements. The present invention relates to an image pickup apparatus configured by arranging a plurality of lines on a straight line.

[Prior Art] Conventionally, in a document reading method using this type of image pickup device,
There are two methods, a reduction type in which a reduced image is formed and read, and a unit type in which a uniform image is formed and read. In recent years, an equal-magnification type, which has a small optical system, is easy to adjust, and may have a small amount of light, is often used, but the equal-magnification type requires a long sensor.

The color original reading method includes a light source switching method and a three-color separation method using a filter. Further, the filter method uses a single line sensor to sequentially read three colors by switching the three colors. There are a method, a method of simultaneously reading three colors using three line sensors, and a method of simultaneously reading three colors with a single color line sensor configured by on-chip a three-color stripe filter.

In recent years, a three-color filter-on-chip unity-size color sensor capable of high-speed reading has attracted attention. However, in order to use this sensor to read at the same reading density as that of the black and white sensor, a sensor having a reading density three times that of black and white is required.

As described above, a high-density long sensor is required for a three-color filter-on-chip unity-size sensor, but in CCD image sensors and MOS image sensors, photoelectric conversion elements are placed on a silicon wafer. Since it is formed, the chip size of the image sensor is limited by the size of the silicon wafer. For example, when using a 4-inch wafer, the chip size of the image sensor is 100 m.
It will be less than m.

With such an image sensor chip, for example,
To form a line sensor with A4 width (210 mm),
A plurality of such image sensor chips must be arranged. As a method of arranging the plurality of chips, there are a staggered arrangement and a linear arrangement.

The staggered arrangement is easy to arrange because there is an overlapping part,
A buffer memory of several lines is required corresponding to the distance between adjacent chips, and processing of connection positions is also required.

On the other hand, the linear array does not require the processing of the buffer memory and the connecting position as in the staggered array, but a photoelectric conversion element such as a photodiode is arranged up to the end of the chip, and the chip is further improved. It must be cut with high precision and arranged with higher precision on the substrate.

In particular, in the case of a color sensor, since a color separation filter for three colors is required, the photoelectric conversion element density in the main scanning method (line direction) is three times that of a black and white sensor. For example, when the reading density is 16 pixels / mm, the element density of the color sensor is 48
Element / mm, and element pitch is about 20 μm. It is very difficult to form a photodiode within this element pitch and cut it with high precision without damaging it.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide an image pickup apparatus which is easy to manufacture and has substantially no deterioration in image quality at the joint portion of the ends of the color sensor chip. Especially.

[Means for Solving Problems] In order to achieve such an object, according to the present invention, a plurality of photoelectric conversion elements are arranged in a line, and a plurality of color filters are arranged on the photoelectric conversion element in a predetermined manner. A plurality of color sensor chips arranged in a repeating order are arranged on a straight line, and the hue of the plurality of color filters is affected in a gap between adjacent color sensor chips of the color sensor chips. Of the first color among the outputs of the color separation means and the color separation means for separating and outputting a plurality of color signals from the output of the image pickup means. And an interpolating means for interpolating the missing portion from the output of the color signal corresponding to the color.

[Operation] In the present invention, in the joint portion at the end of the color sensor chip, only one photoelectric conversion element of a color having a small influence on the hue is thinned out, and the signal of the missing portion is supplied to the pixels of the surrounding pixels. Since the data is interpolated with respect to the same color, it is possible to provide an image pickup apparatus which is easy to manufacture and has substantially no deterioration in image quality.

[Examples] Hereinafter, the present invention will be described in detail with reference to the drawings.

Generally, in an apparatus that reads a color original and outputs a color print, yellow (Y), magenta (M), or cyan (C) ink or toner is usually used as a color material of a color printer. According to the human visual characteristics, the resolution of Y is the worst among these three, and it is difficult to detect the density change.

Based on such a fact, in the present invention, for example, one photoelectric conversion element in which a filter corresponding to the color material Y of the printer is arranged is thinned out, and a signal corresponding to the signal is output with the same color characteristic of the preceding and following pixels. It was confirmed that no visual difference could be found even if interpolation was performed using the signal of the element.

Similarly, when the three color separation filters of the color sensor are primary colors of red (R), green (G) and blue (B), the color material Y of the printer corresponds to the complementary color B.
Therefore, the filter corresponding to B is arranged 1
It was confirmed that no difference can be found visually even if two photoelectric conversion elements are thinned out and the signal corresponding to the signal is formed by interpolation with the signals of the elements of the same color characteristics of the pixels before and after.

According to the present invention, based on the above recognition, when the color sensor chips are arranged in series, the photoelectric conversion elements of one pixel of B or C corresponding to the color material Y of the printer are thinned out at the connecting portion. Constitute.

1 shows an embodiment of the present invention in which the photoelectric conversion elements of B of FIG. 1 are thinned out, where 1 is a substrate, 2 is a first color sensor chip, 3 is a second color sensor chip, and both chips 1 and A connecting portion 4 is formed between the two. 5R, 5G, 5B
Is an R, G, B photoelectric conversion element in which a R, G, B three-color stripe filter is on-chip arranged on the first and second chips 2 and 3. Here, one pixel is configured by one set of elements 5R, 5G, 5B. In this example, one B element 5B is thinned out in the connecting portion 4. As the photoelectric conversion elements 5R, 5G, 5B, various ones such as photoconductors, photodiodes, phototransistors, MOS transistors, MOS capacitors can be used.

When the three color separation filters of the color sensor are complementary colors of yellow (Y), green (G) and cyan (C), they are usually converted into R, G and B signals as follows.

R = Y−G G = G B = C−G Therefore, the color material Y of the printer corresponds to the element C of the color sensor, and in this case, as shown in FIG. In the part 4 of 1), one C element 6C is thinned out and arranged. Where 6Y, 6G, 6C
Is a Y, G, C photoelectric conversion element in which a Y, G, C three-color stripe filter is arranged on-chip on the first and second chips 2 and 3. Here, one set of elements 6Y, 6G, and 6C constitutes one pixel.

In the present invention, by thinning out only one element in the connecting portion 4 as described above, there is a margin in the cutting accuracy and the alignment accuracy of the ends of the sensor chips 1 and 2, so that the color sensor can be easily manufactured. For example, 16 pixels / m
In a high-density color line sensor with an m (element density of 48 elements / mm), by thinning out only one element, a margin of about 20 μm can be obtained, which makes it practically manufacturable.

Next, an example of a circuit for interpolating a thinned signal from one element in processing a signal from the color sensor of the present invention as described above will be described with reference to FIG.

In FIG. 3, the R, G, B serial signals from the color sensor chip shown in FIG. 1 are supplied from the input terminal 11 to the sample hold circuit 12, where the R, G, B parallel signals 13R, 13 are supplied.
Convert to G, 13B and A / D these parallel signals 13R, 13G, 13B
After being converted into digital signals 15R, 15G, 15B in the conversion circuit 14, these R, G, B signals 15R, 15G, 15B are written in the corresponding line buffer memories 16R, 16G, 16B.

Here, digital signals 15R, 15G, 15 obtained according to the serial signals of R, G, B from the plurality of color sensor chips 2, 3
B to the R, G, and B line buffer memories 16R and 16
When writing to G, 16B to obtain R, G, B color signals for one line, the interpolation circuit 17 interpolates the signal corresponding to the thinned B element. That is, in the case of FIG. 3, the B signal corresponds to the printer Y and is subtracted for one pixel. Therefore, in the interpolation circuit 17, when writing to the B line buffer memory 16B, the connection is made. It is easy to write the signal from the B element of the pixel immediately before the pixel to be interpolated in the section 1) or the signal from the B element of the next pixel as the signal from the B element of the pixel.

Alternatively, the interpolation circuit 17 may be configured to take the average value of the signals from the B elements of the preceding and following pixels and write this average value as the signal from the B element of the pixel.

Also in the case of the YGC system filter of FIG. 2, the interpolation circuit can be configured in the same manner as in FIG.

[Effects of the Invention] As described above, according to the present invention, a photoelectric conversion element of a color that has little influence on the hue at a joint portion at the end of a color sensor chip on which a three-color filter is on-chip, for example, Y of a printer. By adopting a structure in which only one element for extracting a signal corresponding to is thinned out, it is easy to manufacture a color line sensor in which a plurality of sensor chips are linearly arranged, and the yield is improved.

Moreover, in the image pickup apparatus of the present invention, the signal for the element thinned out by one element is formed by interpolating with the data for the same color of the surrounding pixels,
Even in this case, there is practically no deterioration in image quality.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention having two sensor chips in a linear array on-chip with an RGB filter, and FIG. 2 is two sensors in a linear array on-chip with a YGC filter. FIG. 3 is a schematic view showing another embodiment of the present invention having a chip, and FIG. 3 shows signals of elements thinned out when writing signals in one line for each color into a line buffer memory. It is a block diagram showing an example of a circuit formed by interpolation. 1 ... Substrate, 2,3 ... Color sensor chip, 4 ... Connecting part, 5R, 5G, 5B ... R, G, B photoelectric conversion element, 6Y, 6G, 6C ... Y, G, C photoelectric conversion Element, 11 …… Input terminal, 12 …… Sample hold circuit, 13R, 13G, 13B …… Parallel signal, 14 …… A / D conversion circuit, 15R, 15G, 15B …… Digital signal, 16R, 16G, 16B… … Line buffer memory, 17… Interpolation circuit.

Claims (1)

[Claims] 1. A color sensor chip having a plurality of photoelectric conversion elements arranged in a line, and a plurality of color filters arranged on the photoelectric conversion element in a predetermined repeating order is arranged in a straight line. And an image pickup unit configured to arrange a color filter so that a first color of the plurality of color filters, which has a small influence on a hue, is omitted in a gap portion between adjacent color sensor chips of the color sensor chip. A color separation unit that separates and outputs a plurality of color signals from the output of the image pickup unit; and an interpolation unit that interpolates a missing portion from the output of the color signal corresponding to the first color of the output of the color separation unit. An image pickup apparatus comprising: