JP2006332250A - Line image sensor with two or more light receiving element rows - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly sensitive and low-cost line image sensor by enlarging a light receiving surface area by arranging a suitable light receiving element, without increasing the silicone area of a photoelectric conversion device. <P>SOLUTION: A line image sensor R formed on a common substrate comprises an R light receiving element rows 1 where R light receiving elements R1, R2 and the like are arranged in a line shape formed with R filters; a G light receiving element rows 2 where G light receiving elements G1, G2 and the like are arranged in a line shape formed with G filters; a B light receiving element rows 3 where B light receiving elements B1, B2 and the like are arranged in a line shape formed with B filters; a circuit 7 which processes and outputs signals from each light receiving element rows 1-3; and wiring parts 11, 21 and 31 which connects each light receiving elements of each light receiving element rows 1-3 and the circuit 7. Sequentially from a side near the circuit 7 of the subscanning direction; the B light receiving element rows 3, the G light receiving element rows 2, and the R light receiving element rows 1 are arranged one by one. For every light receiving element rows 1-3, the light receiving surface are of a light receiving element is varied by utilizing the regions other than the regions through which the wiring 11, 21 and 31 pass among empty regions between the light receiving. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a line image sensor having a plurality of light receiving element arrays, and more particularly to an arrangement of effective light receiving elements of a line image sensor.

  In recent years, in the field of photoelectric conversion devices, CCD sensors using a reduction optical system and equal-magnification contact image sensors mounted with a plurality of photoelectric conversion devices have been actively developed (for example, Patent Document 1). reference). FIG. 4 is a layout view of the light receiving elements in the color line sensor of the conventional example proposed in Patent Document 1.

  In FIG. 4, a color line sensor 2024 is applied to an image scanner (image reading device), and RGB primary color filters are formed on each light receiving element made of a photodiode. Reference numeral 2024-1 denotes a light receiving element array in which light receiving elements R... R on which an R filter that transmits a red wavelength component in visible light is formed are arranged in one line. Reference numerals 2024-2 and 2024-3 denote light-receiving element arrays in which light-receiving elements G... G, B... B formed with a G filter and a B filter that transmit wavelength components of green light and blue light are arranged in one line, respectively. It is. These three light receiving element arrays 2024-1, 2024-2, and 2024-3 form RGB 3 line reading lines and generate charges corresponding to the amount of light incident on each light receiving element during a predetermined accumulation time.

  2024-4 is a CCD analog shift register 2024-5 as a charge transfer unit for transferring charges accumulated in the respective light receiving elements of the three light receiving element arrays 2024-1, 2024-2, and 2024-3. Is an output amplifier for converting a charge signal into a voltage and outputting it as a voltage output signal.

  The light receiving element arrays 2024-1, 2024-2, and 2024-3 having different optical characteristics of the RGB3 lines are arranged in parallel to each other so as to read the same line. The CCD analog shift register 2024-4 is arranged in parallel with and adjacent to the light receiving element array 2024-3 at the outer position of the three lines of light receiving element arrays 2024-1, 2024-2, and 2024-3. Each of the light receiving element arrays 2024-1, 2024-2, and 2024-3 and the CCD shift register 2024-4 have a monolithic structure on the same silicon chip.

The respective light receiving elements are arranged so that the pixel pitch in the main scanning direction in each line is 42 μm, which is equal to the size of the opening of one pixel in the main scanning direction. The light receiving elements are arranged so that the interval between the lines is 42 μm, which is equal to the size of the opening of one pixel in the sub-scanning direction. In the above prior art, all the light receiving elements have the same light receiving area.
Japanese Patent Laid-Open No. 2003-32437

  In the line image sensor having a plurality of light receiving element rows as shown in FIG. 4 of Patent Document 1 described above, the sensitivity of the light receiving elements is not equal even if the light receiving areas of the light receiving elements are made equal. The cause is that it is difficult to make the transmittance of the filter equal to each light wavelength, and silicon used as a photoelectric conversion element material has different photoelectric conversion rates for each light wavelength.

  Therefore, a photoelectric conversion element that separates the input light components into red, green, blue, and three colors has the same sensitivity. Therefore, a means for changing the amplifier gain or a part of the light receiving area of the light receiving element having high sensitivity is provided. In general, a means for shielding light with a metal layer and matching the light receiving element with the lowest sensitivity is used.

  FIG. 2 shows a light receiving element row arrangement image diagram of a color line sensor having a light receiving element row in which a part of the light receiving region is shielded with metal. However, the means (see FIG. 2) for shielding a part of the light receiving region of the light receiving element having high sensitivity with the metal layer generates a useless space and is not an ideal design method.

  The present invention has been made in consideration of such a conventional situation, and without increasing the silicon area of the photoelectric conversion device, by arranging an appropriate light receiving element, the light receiving area can be expanded, and high sensitivity and low cost. An object is to provide a simple line image sensor.

  In order to achieve the above object, a line image sensor having a plurality of light receiving element arrays according to the present invention is provided on a common substrate on which a main scanning direction and a sub-scanning direction of the line image sensor are defined. A plurality of light receiving element arrays in which color filters are formed along a line and arranged in a line at predetermined intervals and having different sensitivities determined by the transmittance of the color filter and the photoelectric conversion rate of the light receiving elements. And a circuit unit that processes and outputs signals from the plurality of light receiving element rows, and a plurality of wirings that electrically connect the light receiving elements of the plurality of light receiving element rows and the circuit unit, The plurality of light receiving element arrays are arranged in parallel with each other at a predetermined interval in the sub-scanning direction, the circuit unit is disposed on one outer side of the plurality of light receiving element arrays in the sub-scanning direction, and the plurality of wirings are arranged in front In the line image sensor arranged through the empty area between the respective light receiving elements in the plurality of light receiving element arrays, the light receiving element array having the highest sensitivity among the plurality of light receiving element arrays and the wiring in the empty area are arranged. From the high sensitivity to the low sensitivity, the remaining light receiving element rows are arranged on the side closest to the circuit portion in the sub-scanning direction so that the area of the passing region is the largest. In order, the area of the empty region through which the wiring passes sequentially becomes smaller than the light receiving element array having the highest sensitivity, in a state parallel to the light receiving element array having the highest sensitivity and the main scanning direction, The light receiving areas of the light receiving elements are arranged for each of the plurality of light receiving element rows by sequentially arranging the empty areas other than the area through which the wiring passes from the side closer to the circuit unit in the sub-scanning direction. Different Wherein the is caused al.

  In the present invention, the light receiving element array having the highest sensitivity has the smallest light receiving area of the light receiving element, and the remaining light receiving element arrays are arranged in order from the highest sensitivity to the lowest in the empty area. The light receiving area of the light receiving element may be configured to be sequentially larger than the light receiving element array having the highest sensitivity using a region other than the region through which the wiring passes.

  In the present invention, the plurality of light receiving element arrays include a first light receiving element array in which a plurality of light receiving elements on which a first color filter that transmits a red component wavelength in visible light is formed are arranged in a line. A second light receiving element array in which a plurality of light receiving elements formed with a second color filter that transmits a green component wavelength in visible light are arranged in a line, and a blue component wavelength in visible light A plurality of light receiving elements in which a third color filter that transmits light is arranged in a line, and sequentially from the side closer to the circuit unit in the sub-scanning direction to the side farther from the side. A third light receiving element array, the second light receiving element array, and the first light receiving element array may be sequentially arranged.

  According to the present invention, the empty area formed between the light receiving elements of the plurality of light receiving element arrays is made the light receiving area of the light receiving elements, so that the pitch of the light receiving element arrays in the sub-scanning direction is not changed, and thus the photoelectric conversion device Therefore, it is possible to increase the light receiving area without increasing the silicon area, and to provide a line image sensor with higher sensitivity than the conventional technique at a low cost.

  The best mode for carrying out a line image sensor having a plurality of light receiving element arrays according to the present invention will be described below in detail with reference to the drawings.

  The line image sensor according to the present embodiment is based on the relationship between the empty area generated between the light receiving elements arranged in a line in the plurality of light receiving element rows, the photoelectric conversion rate of the light receiving element, and the transmittance of the color filter. High sensitivity is realized by arranging the light receiving elements in each row at appropriate positions. In the following description, the “sensitivity” of the light receiving element is determined by the photoelectric conversion rate of the light receiving element and the transmittance of the color filter.

  Specifically, this embodiment includes a circuit unit in which a plurality of light receiving element arrays are arranged in parallel in the sub-scanning direction on a common substrate, and processes and outputs signals from the plurality of light receiving element arrays. The line image sensor which has is applied. In this configuration, the light receiving element array having the highest sensitivity is arranged on the closest side (directly above or directly below) of the circuit unit in the sub-scanning direction, and the remaining light receiving element arrays are arranged in the order of the highest sensitivity. In parallel with the high light receiving element array, it is arranged in a direction away from the circuit section in the sub-scanning direction. Thereby, the empty area formed between the light receiving elements in the light receiving element array is made the light receiving area of the light receiving elements. In this way, a line image sensor that does not change the pitch of the light receiving element rows in the sub-scanning direction and has higher sensitivity than the prior art is realized.

  FIG. 1 shows a light receiving element arrangement image diagram of a color line sensor having a plurality of light receiving element rows.

  The color line sensor 100 shown in FIG. 1 includes a light receiving element array 1 (hereinafter referred to as “R light receiving element array”), a light receiving element array 2 (hereinafter referred to as “R light receiving element array”) as a plurality of light receiving element arrays formed on a common substrate. “G light receiving element array”) and light receiving element array 3 (hereinafter referred to as “B light receiving element array”) are arranged.

  The R light receiving element array 1 includes light receiving elements R1, R2, R3,... (Hereinafter referred to as “R light receiving elements”) in which a color filter (R filter) that transmits a red wavelength component in visible light is formed. They are arranged in a line. The G light receiving element array 2 includes light receiving elements G1, G2, G3,... (Hereinafter referred to as “G light receiving elements”) in which color filters (G filters) that transmit green wavelength components in visible light are formed. They are arranged in a line. The B light receiving element array 3 includes light receiving elements B1, B2, B3,... (Hereinafter referred to as “B light receiving elements”) in which color filters (B filters) that transmit blue wavelength components in visible light are formed. They are arranged in a line.

  Among these, the sensitivity of the light receiving elements increases in the order of the R light receiving element array 1, the G light receiving element array 2, and the B light receiving element array 3, as will be described later. In FIG. 1, a is a dimension in the main scanning direction of the light receiving area of the R, G, B light receiving elements, d is an arrangement interval (pitch) in the main scanning direction of the R, G, B light receiving elements, and f is R, G. , B shows the arrangement interval (pitch) in the sub-scanning direction of the light receiving elements.

  The color line sensor 100 is individually connected to each R light receiving element R1, R2, R3,... In the R light receiving element array 1 as a circuit formed on a common substrate with a plurality of light receiving element arrays. Read circuit 4 for R light receiving element, read circuit 5 for G light receiving element individually connected to each G light receiving element G1, G2, G3,. , Each of the B light receiving elements B1, B2, B3,...

  Further, the color line sensor 100 processes and outputs signals from the R, G, and B light receiving element arrays 1, 2, and 3 as circuits and wirings formed on a common substrate with a plurality of light receiving element arrays. The circuit unit 7, output readout wirings 11 ... 11 for the R light receiving element connected between the circuit unit 7 and the readout circuit 4 for the R light receiving element, the circuit unit 7 and the readout circuit 5 for the B light receiving element, Output readout wirings 21... 21 for the G light receiving elements connected between the B, and output readout wirings 31... 31 for the B light receiving elements connected between the circuit section 7 and the readout circuit 6 for the B light receiving elements. Have

  In FIG. 1, 101 is an empty area formed between two light receiving elements R and R adjacent in the main scanning direction in the R light receiving element array 1, and 102 is adjacent in the main scanning direction in the G light receiving element array 2. An empty area 103 formed between the two light receiving elements G and G is an empty area formed between the two light receiving elements B and B adjacent in the main scanning direction in the B light receiving element array 3.

  As shown in FIG. 1, depending on the positional relationship between the R, G, B light receiving element arrays 1, 2, 3 and the circuit unit 7, the number of output read wirings in other columns passing through the own column differs. Therefore, the areas of the empty areas 101, 102, and 103 are different. Specifically, none of the output read wirings 21 and 31 of the G and B light receiving element arrays 2 and 3 pass through the empty area 101 in the R light receiving element array 1, and the empty area 102 in the G light receiving element array 2. In this case, only the output readout wiring 11 of the R light receiving element array 1 passes, and the output readout wirings 11 and 21 of the R and G light receiving element arrays 1 and 2 pass through the empty area 103 in the B light receiving element array 3. Passing through. As the number of output read wirings increases, the areas of the empty regions 101, 102, and 103 are smaller. That is, the area of the empty area 101 between the R light receiving elements in the R light receiving element row 1 arranged on the side farthest from the circuit unit 7 in the sub scanning direction (the lower side in the drawing) is the largest, and the circuit in the sub scanning direction The area of the empty region 103 between the B light receiving elements in the B light receiving element row 3 arranged on the side closest to the portion 7 (upper side in the drawing) is the smallest. The area of the empty region 102 between the G light receiving elements in the G light receiving element array 2 arranged between the two is smaller than the area of the empty region 101 between the R light receiving elements and larger than the area of the empty region 103 between the B light receiving elements. .

  Therefore, in this embodiment, the sensitivity is improved by effectively utilizing the empty areas 101, 102, and 103 of the columns having different areas as the light receiving areas of the light receiving elements of the columns. A specific implementation method will be described in the following example.

  Here, the sensitivity of the light receiving element is represented by S (Sensitive), the sensitivity of the R light receiving element is S_R, the sensitivity of the G light receiving element is S_G, and the sensitivity of the B light receiving element is S_B. When each is different as in the formula (1), the sensitivity of the B light receiving element is the highest, the sensitivity of the R light receiving element is the lowest, and the sensitivity of the B light receiving element is the sensitivity of the B light receiving element and the sensitivity of the G light receiving element. Intermediate.

S_B>S_G> S_R (1)
In FIG. 2, since each light receiving element has the same sensitivity, a part of the light receiving regions of the B and R light receiving elements having high sensitivity are shielded by the metal layers (light shielding layers) 111 and 112, and the most sensitive is obtained. The arrangement | positioning image figure of R, G, B light receiving element row | line | column 1, 2, 3 at the time of matching with a low R light receiving element is shown.

  In FIG. 2, the dimension in the main scanning direction in the light receiving area of the R light receiving element is a, and the dimension in the main scanning direction in the light receiving area of the G light receiving element where a part of the light receiving region is shielded by the metal layer 111 is b. When the dimension in the main scanning direction in the light receiving area of the B light receiving element in which a part of the light receiving region is shielded by the layer 112 is c, a> b> c. Therefore, as shown in FIG. 2, the means for shielding a part of the light receiving regions of the B and R light receiving elements having high sensitivity with the metal layers 111 and 112 generates useless space, and is an ideal design method. Absent. This is as described above.

  On the other hand, FIG. 3 shows an arrangement image diagram of the R, G, and B light receiving element rows 1, 2, and 3 when the light receiving areas are different for each row.

  Here, the light receiving area of the light receiving element is represented by A (Area), the light receiving area of the R light receiving element is A_R, the light receiving area of the G light receiving element is A_G, and the light receiving area of the B light receiving element is A_B. Are different from each other as in the above formula (1), the sensitivity of the light receiving elements in all the rows can be easily made equal by setting the light receiving area as in the following formula (2).

A_B <A_G <A_R (2)
In FIG. 3, the B light receiving element having the highest sensitivity does not need to expand the light receiving area when the sensitivity is sufficient even without increasing the light receiving area. The R light receiving element having the lowest sensitivity uses the empty area 101 to expand the light receiving area. The B light receiving element, which is an intermediate sensitivity between the sensitivity of the B light receiving element and the sensitivity of the G light receiving element, uses the empty area 103 to expand the light receiving area. That is, in FIG. 3, the dimension in the main scanning direction in the light receiving area of the R light receiving element is a, the dimension in the main scanning direction in the light receiving area of the G light receiving element is g, and the dimension in the main scanning direction in the light receiving area of the B light receiving element. Where h is a <g <h.

  When the light receiving area of all the light receiving elements is effectively used by the method shown in FIG. 3, it is easy to realize the same sensitivity as all the light receiving elements as in the following formula (3).

S_B = S_G = S_R (3)
Therefore, according to the present embodiment, the B light receiving element row having the highest sensitivity is arranged immediately above or immediately below the circuit unit, and the remaining G and R light receiving element rows are arranged in descending order of sensitivity in order of high sensitivity. It is arranged in parallel to the columns in a direction away from the circuit unit. As a result, by effectively utilizing the empty area formed between the light receiving elements of the light receiving element array to make the light receiving area of the light receiving element, the pitch of the light receiving element array in the sub-scanning direction is not changed, and compared with the prior art A highly sensitive line image sensor can be realized. According to this, even if the short side length of the photoelectric conversion device is reduced, it is possible to provide an inexpensive color line sensor that can achieve the same sensitivity as that of the prior art. This effect can be maximized when applied to a low-cost multi-line sensor that will be required in the future.

FIG. 4 is a light receiving element arrangement diagram for explaining an empty area in a light receiving element row of a color line sensor according to an embodiment of the present invention. FIG. 2 is a light receiving element arrangement diagram for explaining a case where a part of the light receiving region of the color line sensor shown in FIG. 1 is shielded by metal. FIG. 2 is a light receiving element arrangement diagram for explaining a case where a light receiving area is changed for each column using an empty area in the light receiving element column of the color line sensor shown in FIG. 1. It is a light receiving element arrangement | positioning figure of the color line sensor of a prior art (patent document 1).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 R light receiving element row 2 G light receiving element row 3 B light receiving element row 4 R light receiving element read circuit 5 G light receiving element read circuit 6 B light receiving element read circuit 7 Circuit part 11 R light receiving element output read wiring 21 G light receiving Element output read wiring 31 B Light receiving element output read wiring 100 Color line sensor 101 Empty area (between R light receiving elements)
102 Free space (between G light receiving elements)
103 Free space (between B light receiving elements)
111 G light receiving element metal layer (light shielding layer)
112 B Light receiving element metal layer (light shielding layer)

Claims (3)

A plurality of light receiving elements in which color filters are formed along the main scanning direction are arranged in a line at predetermined intervals on a common substrate in which the main scanning direction and the sub scanning direction of the line image sensor are defined. A plurality of light receiving element arrays having different sensitivities determined by the transmittance of the color filter and the photoelectric conversion rate of the light receiving elements, a circuit unit for processing and outputting signals from the plurality of light receiving element arrays, and the plurality A plurality of wirings that electrically connect each light receiving element of the light receiving element row and the circuit unit,
The plurality of light receiving element arrays are arranged in parallel with each other at a predetermined interval in the sub-scanning direction, the circuit unit is disposed on one outer side of the plurality of light receiving element arrays in the sub-scanning direction, and the plurality of wirings are arranged In the line image sensor arranged through the empty area between the light receiving elements in the plurality of light receiving element rows,
The light receiving element row having the highest sensitivity among the plurality of light receiving element rows is arranged on the side closest to the circuit unit in the sub-scanning direction so that the area of the empty region through which the wiring passes is maximized. ,
Among the plurality of light receiving element rows, the remaining light receiving element rows are arranged in order from the high sensitivity to the low sensitivity, and the area of the region through which the wiring passes in the empty area is higher than the light receiving element row having the highest sensitivity. In order to sequentially decrease, the light receiving element array having the highest sensitivity and the main scanning direction in parallel with each other, are sequentially arranged from the side closer to the circuit unit in the sub scanning direction,
A line image sensor having a plurality of light receiving element rows, wherein a light receiving area of the light receiving element is made different for each of the plurality of light receiving element rows by utilizing a region other than the region through which the wiring passes among the empty regions. . The light receiving element array having the highest sensitivity has the smallest light receiving area of the light receiving element,
The remaining light receiving element arrays receive light of the light receiving elements in order from the highest sensitivity to the lower ones using the remaining areas other than the area through which the wiring passes, than the light receiving element array having the highest sensitivity. 2. A line image sensor having a plurality of light receiving element rows according to claim 1, wherein the line image sensor has a structure in which the area gradually increases. The plurality of light receiving element rows are:
A first light-receiving element array in which a plurality of light-receiving elements formed with a first color filter that transmits a red component wavelength in visible light are arranged in a line;
A second light receiving element array in which a plurality of light receiving elements in which a second color filter that transmits a green component wavelength in visible light is formed are arranged in a line;
A third light receiving element array in which a plurality of light receiving elements formed with a third color filter that transmits a blue component wavelength in visible light are arranged in a line;
The third light receiving element array, the second light receiving element array, and the first light receiving element array are sequentially arranged in this order from the side closer to the circuit unit in the sub-scanning direction to the side farther from the circuit unit. A line image sensor having a plurality of light receiving element rows according to claim 1.

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