JPS6278956A - Color sensor - Google Patents

Abstract

PURPOSE:To facilitate manufacture and to improve yield by thinning out only one photoelectric transducer of a color which exerts less influence upon hues at a joint part at the end of a color sensor chip formed by mounting three primary color filters on a chip. CONSTITUTION:One picture element consists of a group of photoelectric transducers 5R, 5G, and 5B of red R, green G, and blue B, but one B element 5B is thinned out at a joint part 4. Digital signals 15R, 15G, and 15B obtained corresponding to serial signals of R, G, and B from plural color sensor chips 2 and 3 are written in respective line buffer memories 16R, 16G, and 16B to obtain respective color signals of R, G, and B for one line. In this case, a signal corresponding to the thinned-out B element is interpolated by an interpolating circuit 17. When the signal is written in the line buffer memory 16B of B, a signal from the B element of picture element which is right before a picture element to be interpolated at the joint part or next picture element is used as a signal from the B element of the corresponding picture element to facilitate the writing.

Description

Detailed Description of the Invention [Industrial Application Field] 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 provided on-chip on the photoelectric conversion element. The present invention relates to a color sensor constructed by arranging a plurality of color sensors in a linear manner.

[Prior Art] Conventionally, there are two types of document reading methods using this type of line sensor: a reduction type in which a reduced image is formed and read, and a same-size type in which a same-size image is formed and read. In recent years, the 1-magnification type has been widely used because it has a small optical system, is easy to adjust, and requires a small amount of light; however, the 1-magnification type requires a long sensor.

In addition, color document reading methods include a light source switching method and a three-color separation method using a filter.Furthermore, the one-filter method uses only one line sensor and reads three colors sequentially by switching filters. A sequential reading method, a method that reads three colors simultaneously using three line sensors, and a method that reads three colors simultaneously using a three-color stripe filter on the sensor.
There is a method that reads colors simultaneously.

In recent years, 3-color filter-on-chip, 1-magnification color sensors that are capable of high-speed reading have attracted attention. However, in order to read with the same reading density as a monochrome sensor using this sensor, a sensor with a reading density three times that of the monochrome sensor is required.

As mentioned above, a 3-color filter-on-chip, 1-magnification sensor requires a high-density long sensor, but COD image sensors, MOS image sensors, etc. require photoelectric conversion on a silicon wafer. 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 1.
00III11 or less.

In order to form, for example, an A4 width (210 mm) line sensor using such image sensor chips, a plurality of such image sensor chips must be arranged. ,
There are staggered arrangement and linear arrangement.

Staggered arrangement is easy to arrange because there are overlapping parts, but
Several lines of buffer memory are required for the distance between adjacent chips, and it is also necessary to process the joint positions.

On the other hand, with a linear array, there is no need to process the buffer memory or joint positions as in the case of a staggered array, but photoelectric conversion elements such as photodiodes are placed all the way to the edge of the chip, making the chip more compact. They must be cut with high precision and arranged on the substrate with high precision.

In particular, in the case of a color sensor, color separation filters for three colors are required, so the density of photoelectric conversion elements in the main scanning direction (line direction) is three times that of a monochrome sensor. For example, when the reading density is 16 pixels/1I11, the element density of the color sensor is 48 elements/■, and the element pitch is approximately 20IL1.
It becomes 1. It is extremely difficult to form a photodiode within this element 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 eliminate the above-mentioned drawbacks and provide a linear array color sensor that is easier to manufacture. It is about providing.

/'f Means for Solving the Problem] In order to achieve such an object, the present invention provides a method in which a plurality of photoelectric conversion elements are arranged in a line, and a three-color stripe filter is arranged on the photoelectric conversion element. In a color sensor configured by arranging a plurality of color sensor chips in a straight line, in the connecting portion between adjacent color sensor chips among these color sensor chips,
The present invention is characterized by thinning out only one photoelectric conversion element for a color that has little effect on hue among the three-color stripe filter.

[Function] According to the present invention, in a color line sensor in which a plurality of color sensor chips are arranged in a straight line, one of the connecting parts of the ends of each chip is arranged with a color filter that has little influence on the hue. By thinning out the photoelectric conversion elements, it is possible to provide a color sensor that is easy to manufacture in terms of cutting accuracy and arrangement accuracy, with less damage caused by cutting.

[Example] The present invention will be described in detail below with reference to the drawings.

In general, in devices that read color originals and output color prints, the color materials used in color printers are usually yellow (Y), magenta (M), and cyan (C).
According to human visual characteristics, the resolution of Y is the worst among these three, and it is difficult to detect changes in density.

In light of these facts, the present invention thins out one photoelectric transducer element in which a filter corresponding to the printer's color material Y is disposed, and converts the signal corresponding to the same color characteristic of the previous and subsequent pixels. It was confirmed that no difference could be visually detected even if the signals of the elements were interpolated.

Similarly, if the color sensor's three-color separation filter is the primary colors red (R), green (G), and blue (B), the printer's color material Y corresponds to its complementary color B.
Therefore, 1 where the filter corresponding to B is arranged
It was confirmed that even if one photoelectric conversion element is thinned out and the signal corresponding to that signal is interpolated with the signals of the elements of the same color characteristics of the previous and subsequent pixels, no difference can be detected visually.

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

FIG. 1 shows an embodiment of the present invention in which the photoelectric conversion elements of B are thinned out, where l 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, 5
G, 5B are R, G on the first and second chips 2 and 3.
, B three-color stripe filters are arranged on-chip for R, G, and B photoelectric conversion elements. Here, one pixel is composed of one set of elements 5R, 5G, and 5B. In this example, one B element 5 is provided in the connecting portion 4.
B is being thinned out. In addition, photoelectric conversion elements 5R, 5G, 5
As B, various types such as a photoconductor, a photodiode, a phototransistor, a MOS transistor, and a MOS capacitor can be used.

If the three-color separation filter of the color sensor is complementary color yellow (Y), green (G), and cyan (C), it is converted into R, G, and B signals as in the normal method.

R=Y-G G=G B=C-G Therefore, it is element C of the color sensor that corresponds to color material Y of the printer, and in this case, the sensor chip is connected as shown in Figure 2. In the portion 4, one C element 6C is thinned out and arranged. Here, 6Y, 6
G, 8C are Y on the first and second chips 2 and 3,
These are Y, G, and C photoelectric conversion elements in which G and C three-color stripe filters are arranged on-chip. Here, one pixel is composed of one set of elements 8Y, 8G, and 6G.

In the present invention, by thinning out only one element in the connecting portion 4 as described above, there is a margin in cutting precision and arrangement precision at the end of the sensor chip 1.2, thereby facilitating the manufacture of a color sensor. For example, in a high-density color line sensor of 16 pixels/I1m (element density is 48 elements/I1m), by thinning out only one element, a margin of about 20 pLm is created, making it practically possible to manufacture.

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

In FIG. 3, R, G, and B serial signals from the color sensor chip shown in FIG. The parallel signals 13R, 13G, and 13B are converted to the AID conversion circuit 14.
After converting into digital signals 15R, 15G, 15B, these R, G, B signals 15R, 15G, 15B
Each corresponding line buffer memory 18R, IEi
Write to G, 16B.

Here, R from the plurality of color sensor chips 2 and 3,
Digital signal 1 obtained according to G and B serial signals
5R, 15G, and 15B are written to the R, G, and B line buffer memories 18R, 18G, and 18B, respectively, to obtain 1947 R, G, and B color signals, corresponding to the thinned out B elements. The signal is interpolated by an interpolation circuit 17. That is, in the case of FIG. 3, the B signal corresponds to the printer Y, and since it is subtracted for one pixel, the interpolation circuit 17 uses the connection when writing to the B line buffer memory 18B. It is easy to write the signal from the B element of the pixel immediately before the pixel to be interpolated or the signal from the B element of the primary pixel as the signal from the B element of the pixel in question.

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

In the case of the YGC filter shown in FIG. 2, an interpolation circuit can be constructed in the same manner as shown in FIG.

[Effects of the Invention] As explained above, according to the present invention, a photoelectric conversion element of a color that has little effect on the hue, for example, Y of a printer, is used at the connecting part of the end of a color sensor chip having a three-color filter on-chip. 1 element to extract the corresponding signal
By using a structure in which only the elements are thinned out, it becomes easier to manufacture a color line sensor in which a plurality of sensor chips are arranged in a straight line, and the yield is also improved.

Moreover, in a color original reading device using a color line sensor according to the present invention.

A signal for an element that has been thinned out by one element is formed by interpolating data for the same color of surrounding pixels, but even in this case, there is almost no deterioration in image quality in practice.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of the present invention having two sensor chips arranged in a linear arrangement with an on-chip RGB filter, and Fig. 2 shows two sensors arranged in a linear arrangement with an on-chip YGC filter. FIG. 3 is a schematic diagram illustrating another embodiment of the present invention having chips, and FIG. FIG. 2 is a block diagram showing an example of a circuit formed by interpolation. 1... Board, 2.3... Color sensor chip, 4... Connecting part. 5R, 5G, 5B...R, G, B photoelectric conversion element, BY
, 8G, 8G...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, 18R,
16G, 18B...Line buffer memory, 17...
・Interpolation circuit. Figure 1: Honda's Sun and Moon's Tora Se I Column Figure 1 A-month color secessor's F-ha circuit n Peng greeting IJ
Figure 3 of the block diagram shown in i.

Claims (3)

[Claims] (1) In a color sensor configured by linearly arranging a plurality of color sensor chips each having a configuration in which a plurality of photoelectric conversion elements are arranged in a line and a three-color stripe filter is arranged on the photoelectric conversion element, A color sensor characterized in that, in a connecting portion between adjacent color sensor chips of the color sensor chips, photoelectric conversion elements for colors that have little influence on hue among the three-color stripe filters are thinned out by one element. (2) In the color sensor according to claim 1, when the three-color stripe filter is of a red-green-blue type, the photoelectric conversion element for blue is subtracted by one element. color sensor. (3) In the color sensor according to claim 1, when the three-color stripe filter is yellow-green-cyan, the photoelectric conversion element for cyan is subtracted by one element. color sensor.