JP2018101995A - Photoelectric conversion element, image reading device, image forming apparatus, and image reading method - Google Patents

Abstract

A photoelectric conversion element, an image reading apparatus, an image forming apparatus, and an image reading method capable of preventing a decrease in sensitivity are provided. A plurality of light receiving elements that generate charges for each pixel in accordance with an amount of received light, and a plurality that operates to derive charges generated by the plurality of light receiving elements for each pixel from the plurality of light receiving elements, respectively. The plurality of light receiving elements are arranged in a light receiving region that receives light from the outside, and the plurality of pixel circuits are provided in a non-light receiving region that does not receive light from the outside. It is characterized by that. [Selection] Figure 9

Description

  The present invention relates to a photoelectric conversion element, an image reading apparatus, an image forming apparatus, and an image reading method.

  In an image reading apparatus for reading a document, a conventional CCD is mainly used as a photoelectric conversion element that photoelectrically converts light reflected from the document. In recent years, CMOS linear image sensors have attracted attention as photoelectric conversion elements due to demands for higher speed and lower power consumption for image reading apparatuses. A CMOS linear image sensor is the same as a CCD in that incident light is photoelectrically converted by a photodiode. However, while the CCD transfers charges by a shift register and performs charge-voltage conversion by the charge detector after the transfer, the CMOS linear image sensor performs charge-voltage conversion near the pixel and outputs it to the subsequent stage.

  In addition, a conventional CMOS linear image sensor includes a photodiode (PD) that performs photoelectric conversion, a floating diffusion (FD) that performs charge-voltage conversion of charges accumulated in the PD, a reset circuit that resets the potential of the FD, and an FD A source follower (SF) that buffers the voltage signal and transmits it to the subsequent stage is formed in the pixel. In other words, the conventional CMOS linear image sensor has a problem that the area (opening) of the photodiode is limited and the sensitivity is lowered because a portion (pixel circuit) other than the photodiode is arranged in the pixel.

  This problem is particularly true in a CMOS linear image sensor for a reduction optical system having a smaller pixel size than a contact image sensor (CIS; Contact-Image-Sensor) for the same magnification optical system, even in the same CMOS linear image sensor. Become prominent.

  As a technical example for solving the above problem, for example, Patent Document 1 discloses a CMOS solid-state imaging device in which a pixel row in which a plurality of pixels are arranged in a one-dimensional manner is arranged in a plurality of rows, and each pixel is individually Provided in each pixel, and a second pixel circuit provided in common to the pixels in each column, wherein the second pixel circuit includes the pixel A solid-state imaging device that is disposed outside the column is disclosed.

  However, the conventional CMOS linear image sensor has a problem that the sensitivity is still low because a part of the pixel circuit is configured in the pixel. Further, since there is a common part between colors (RGB) in the pixel circuit, only one of RGB can be read at a time, and it is difficult to increase the speed.

  The present invention has been made in view of the above, and an object thereof is to provide a photoelectric conversion element, an image reading apparatus, an image forming apparatus, and an image reading method capable of preventing a decrease in sensitivity.

  In order to solve the above-described problems and achieve the object, the present invention provides a plurality of light receiving elements that generate charges for each pixel in accordance with an amount of received light, and a plurality of charges generated by the plurality of light receiving elements. A plurality of pixel circuits that operate so as to be derived for each pixel from each of the light receiving elements, wherein the plurality of light receiving elements are arranged in a light receiving region that receives light from the outside, and the plurality of pixel circuits are external A non-pixel provided in a non-light-receiving region that does not receive light from the light-receiving element, and the pixel circuit that operates to derive the sub-scanning width of the pixel region in which the light-receiving element generates charges and derives the generated charges The sub-scanning width of the area is substantially equal.

  According to the present invention, it is possible to prevent a decrease in sensitivity.

FIG. 1 is a diagram showing an outline of the configuration of a CMOS area sensor. FIG. 2 is a diagram illustrating a pixel configuration in units of columns of the CMOS area sensor. FIG. 3 is a diagram illustrating an operation example of the CMOS area sensor. FIG. 4 is a diagram showing an outline of a first example of a CMOS linear image sensor. FIG. 5 is a diagram illustrating an operation example of the CMOS linear image sensor. FIG. 6 is a diagram showing an outline of a second example of the CMOS linear image sensor. FIG. 7 is a diagram illustrating a pixel configuration in units of columns in the second example of the CMOS linear image sensor. FIG. 8 is a diagram illustrating an operation example of the CMOS linear image sensor. FIG. 9 is a diagram illustrating an outline of the configuration of the photoelectric conversion element according to the embodiment. FIG. 10 is a diagram illustrating a pixel configuration in units of columns of the photoelectric conversion element illustrated in FIG. 9. FIG. 11 is a diagram illustrating an operation example of the photoelectric conversion element. FIG. 12 is a schematic diagram of a cross section of a photoelectric conversion element showing the position of a signal line that transmits a signal output from a pixel circuit to another circuit. FIG. 13 is a diagram showing an outline of the first embodiment of the photoelectric conversion element. FIG. 14 is a diagram showing an outline of a second embodiment of the photoelectric conversion element. FIG. 15 is a diagram illustrating a pixel configuration in units of columns of photoelectric conversion elements. FIG. 16 is a diagram illustrating an operation example of the photoelectric conversion element. FIG. 17 is a diagram illustrating an outline of an image forming apparatus including an image reading apparatus having a photoelectric conversion element.

  First, the background that led to the present invention will be described by taking as an example a CMOS area sensor in which replacement of a CCD image sensor with a CMOS image sensor has preceded. FIG. 1 is a diagram showing an outline of the configuration of the CMOS area sensor 10.

  The pixel 20 of the CMOS area sensor 10 includes a photodiode (PD) that performs photoelectric conversion that generates a charge according to the amount of received light, and a pixel that operates to derive the charge generated by the photoelectric conversion from the photodiode from the photodiode. Circuit 200. Specifically, the pixel circuit 200 converts the charge generated by the photodiode into a voltage signal and outputs the voltage signal to another circuit in the subsequent stage. The CMOS area sensor 10 is a Bayer array area sensor and uses four R / G / G / B pixels as one unit.

  FIG. 2 is a diagram illustrating a pixel configuration in units of columns of the CMOS area sensor 10 illustrated in FIG. Hereinafter, substantially the same components are denoted by the same reference numerals. The pixel circuit 200 includes a floating diffusion (FD: charge voltage conversion unit) that performs charge-voltage conversion of charges accumulated in the PD, a transfer unit (T, Tr2) that transfers charges to the FD, and a reset unit that resets the potential of the FD. (RS, Tr1), a source follower (SF) that buffers the voltage signal of FD and transmits it to other circuits in the subsequent stage, and a pixel selector (S, Tr3) that selects a pixel. The readout line (SIG (*)) from the pixel circuit 200 is common for each column, and the signal of the pixel 20 is read for each row.

  At this time, since the pixel circuit 200 is configured in the pixel 20, the area (opening) of the PD is limited, and the sensitivity is lowered. In particular, in the area sensor, pixels are spread two-dimensionally due to the configuration, and thus such a decrease in sensitivity becomes an unavoidable problem. Therefore, in an area sensor, it is common to secure an aperture by forming an on-chip lens for each pixel and condensing light on the PD surface, but this leads to an increase in cost and a decrease in yield.

  FIG. 3 is a diagram illustrating an operation example of the CMOS area sensor 10. In the CMOS area sensor 10, since the readout line from the pixel circuit 200 is common for each column, the signal of the pixel 20 is read for each row. As shown in FIG. 3A, R → G → R... Is read in SIG (1), and G → B → G... Is read in SIG (2). The read signals are rearranged for each R / G / B (or R / G / G / B) and transmitted to other circuits not shown.

  FIG. 3B shows the operation of the pixel circuit 200. First, the pixel 20 (row) to be read is selected by the pixel selection unit (S is turned ON). In the selected pixel 20, the FD is reset (RS is turned on), the transfer unit is turned on (T is turned on), and the charge of the PD is transferred to the reset FD. The voltage signal converted by the FD is buffered by the SF and output as a signal of SIG (*) via the readout line. Thereafter, the next pixel row is selected by the pixel selection unit, and reading operations are sequentially performed.

  In SIG, a signal is generally held by a sample and hold circuit. However, when correlated double sampling (CDS) is performed, the signal after RS is turned on (before T is turned on) is held as a reference level. Is done.

  FIG. 4 is a diagram showing an outline of the configuration of the first example of the CMOS linear image sensor. As shown in FIG. 4, the CMOS linear image sensor 12 is, for example, a contact image sensor (CIS; Contact-Image-Sensor), and has a configuration similar to the CMOS area sensor 10. The CMOS linear image sensor 12 is different from the CMOS area sensor 10 in that pixels 22 are arranged in one direction for each color of R / G / B light received through a filter (not shown). The pixel 22 includes a photodiode (PD) and a pixel circuit 220.

  Further, in the CMOS linear image sensor 12, the readout line from the pixel circuit 220 is common for each column, and the signal of the pixel 22 is read for each row. That is, the CMOS linear image sensor 12 serves as a common readout line for RGB and is read for each RGB. Thus, since the CMOS linear image sensor 12 has a configuration similar to that of the CMOS area sensor 10, there is a problem of sensitivity reduction due to the pixel circuit 220.

  FIG. 5 is a diagram illustrating an operation example of the CMOS linear image sensor 12. In the CMOS linear image sensor 12, since the readout line from the pixel circuit 220 is common to RGB, the signal of the pixel 22 is read for each RGB. At this time, SIG (1) to SIG (n) all have the same output and are read out as R → G → B. The operation of the pixel circuit 220 is the same as the operation shown in FIG. The CMOS linear image sensor 12 is similar to the CMOS area sensor 10 in that when correlated double sampling (CDS) is performed, a signal after RS is turned on (before T is turned on) is held as a reference level. .

  FIG. 6 is a diagram showing an outline of the configuration of the second example of the CMOS linear image sensor. FIG. 7 is a diagram illustrating a pixel configuration in units of columns of the second example of the CMOS linear image sensor shown in FIG. As shown in FIG. 6, the CMOS linear image sensor 14 is divided into a pixel circuit that is common to the pixels and a pixel circuit that is not common to the pixels in order to reduce sensitivity reduction due to the pixel circuit. A pixel circuit is disposed outside the pixel.

  That is, as shown in FIG. 6, the CMOS linear image sensor 14 includes a circuit in which the pixel circuit is independent for each pixel (first pixel circuit 240) and a circuit common to the RGB pixels 24 (second pixel circuit 242). It is divided into. The first pixel circuit 240 includes a transfer unit (Tr2, T). The second pixel circuit 242 includes a floating diffusion (FD), a reset unit (Tr1, RS), and a source follower (SF) as pixel circuits common to RGB. The CMOS linear image sensor 14 is the same as the CMOS linear image sensor 12 in that it is a common readout line for RGB. In the CMOS linear image sensor 14, the RGB pixel column pitch is 4/3 lines (4/3 times the pixel sub-scanning size).

  The CMOS linear image sensor 14 can increase the area of the photodiode (PD) because the pixel circuit configured in the pixel 24 is small, but a part of the pixel circuit (first pixel circuit 240) in the pixel 24. Remains, and it cannot be said that the sensitivity is sufficiently improved. Specifically, the PD sub-scanning size is set to 3/4 with respect to the area of the square pixel 24, and the first pixel circuit 240 is arranged in the remaining 1/4 area. That is, it means that 1/4 of the PD area is cut by the first pixel circuit 240, and the situation that the area of the PD is limited by the pixel circuit remains unchanged. That is, the CMOS linear image sensor 14 still has room for improvement in sensitivity, and the pixel area is inefficient.

  Even in the case of a CMOS linear image sensor, since the pixel size is originally large in the case of a contact image sensor (CIS), even a configuration such as the CMOS linear image sensor 14 shown in FIG. 6 is inefficient. There is almost no impact. On the other hand, in the CMOS linear image sensor for the reduction optical system having a pixel size of 1/10 or less of CIS, the influence of the first pixel circuit 240 is large, and the sensitivity of the configuration such as the CMOS linear image sensor 14 is still unsatisfactory. It is enough. This is because even if the pixel size changes, the size of the pixel circuit is substantially the same, so that the smaller the PD area, the greater the influence of the pixel circuit. In the configuration of the CMOS linear image sensor 14, since the second pixel circuit 242 is common to RGB, only one of RGB can be read at a time (line sequential reading). For this reason, the configuration of the CMOS linear image sensor 14 has a problem that the reading operation cannot be speeded up.

  FIG. 8 is a diagram illustrating an operation example of the CMOS linear image sensor 14. As shown in FIG. 8A, the pixel reading method of the CMOS linear image sensor 14 is the same as that of the CMOS linear image sensor 12. Also in this case, since the readout line from the second pixel circuit 242 is common to RGB, the signal of the pixel 24 is read for each RGB.

  Further, as shown in FIG. 8B, the operations of the first pixel circuit 240 and the second pixel circuit 242 are different from the operation shown in FIG. 3B in that the transfer unit (Tr2, T) is a pixel selection unit. It is different that doubles. Therefore, the CMOS linear image sensor 14 selects a pixel column to be read when the charge transfer unit is sequentially turned on, such as R → G → B →. Further, the CMOS linear image sensor 14 also shows that the signal after RS is turned on (before T is turned on) is held as a reference level when correlated double sampling (CDS) is performed in FIG. It is the same as the operation shown.

  The sensitivity of the CMOS linear image sensor 14 is improved, but the first pixel circuit 240 remains in the pixel 24, and it cannot be said that the sensitivity is sufficiently improved. This is due to the presence of the second pixel circuit 242 common to RGB, that is, the configuration of line sequential reading. That is, in the case of line-sequential reading, it is necessary to read out the image signals for three colors of RGB in the period of one line, so that it is read out in a time division manner. As a result, color misregistration occurs. For this reason, the pitch of the RGB pixel rows cannot be increased, and the area for arranging the pixel circuits cannot be secured, so the area of the PD must be reduced. In addition, line-sequential reading cannot be performed at high speed because each color of RGB is read out one by one.

(Embodiment)
Next, an embodiment of the photoelectric conversion element will be described in detail. FIG. 9 is a diagram illustrating an outline of a configuration of the photoelectric conversion element 16 according to the embodiment. FIG. 10 is a diagram illustrating a pixel configuration in units of columns of the photoelectric conversion element 16 illustrated in FIG. 9. The photoelectric conversion element 16 is, for example, a CMOS linear color image sensor that does not include an on-chip lens. In the photoelectric conversion element 16, n pixels 26 are arranged in one direction for each color of R / G / B light received through a filter (not shown).

  Each pixel 26 is provided with a light receiving element (photodiode; PD) that generates an electric charge according to the amount of received light so as to occupy substantially the entire region except a separation band described later. The plurality of pixels 26 are arranged in one direction for each color of received light to form three pixel rows of RGB. Each of the three pixel columns is provided in a light receiving region that receives light from the outside.

  The photoelectric conversion element 16 is provided with a non-pixel region 30 for each pixel so as to be adjacent to each pixel column. The non-pixel region 30 is a non-light receiving region that does not receive light from the outside. The non-pixel region 30 is provided with a pixel circuit 300 that operates to derive charges generated by the PD from the PD for each pixel. The pixel circuit 300 includes a floating diffusion (FD; charge-voltage conversion unit) that performs charge-voltage conversion of charges accumulated in the PD, a transfer unit (T, Tr2) that transfers charges generated by the PD to the FD, and the potential of the FD. Reset section (RS, Tr1) for resetting and a source follower (SF; transmission section) for buffering the voltage signal of FD and transmitting it to other circuits in the subsequent stage. Each of the n pixel circuits 300 independently outputs the signal of the pixel 26 to another circuit in the subsequent stage.

  That is, the photoelectric conversion element 16 can simultaneously read the reflected RGB light, and can increase the pitch of the RGB pixel columns as compared with the case of line-sequential reading. For example, the pitch of 4/3 lines in the CMOS linear image sensor 14 shown in FIG. 6 is expanded to a pitch of 2 lines in the photoelectric conversion element 16. That is, the photoelectric conversion element 16 is formed so that the non-pixel region 30 having an area equivalent to the size of the pixel 26 (sufficient for the area of the pixel circuit) is adjacent to the pixel column. There is no need to divide the common portion and the non-common portion, and all the pixel circuits can be arranged in the non-pixel region 30 for each pixel. Note that since the photoelectric conversion element 16 can read signals independently for each pixel, a pixel selection unit is not necessary.

  As described above, in the photoelectric conversion element 16, the PD occupies the region in the pixel 26 (excluding a separation band described later). That is, the photoelectric conversion element 16 can maximize the PD area in the pixel (or the light receiving region), and the sensitivity is maximized. Further, since the photoelectric conversion element 16 can independently read out the signals of the respective RGB pixels 26, it is possible to speed up the reading operation (simply 3 times that of the line-sequential reading method). The above speed can be increased).

  FIG. 11 is a diagram illustrating an operation example of the photoelectric conversion element 16. In the photoelectric conversion element 16, since the readout lines from the pixel circuit 300 are independent for each pixel 26, the signals of the pixels 26 are read simultaneously, for example, for each of RGB. Further, while the operation of the CMOS linear image sensor 14 shown in FIG. 8B is an RGB sequential operation, each pixel circuit 300 operates at the same timing for each pixel 26 at the same time. Further, the photoelectric conversion element 16 is similar to the CMOS linear image sensor 14 in that, when correlated double sampling (CDS) is performed, a signal after RS is turned on (before T is turned on) is held as a reference level. It is.

  FIG. 12 is a schematic cross-sectional view of the photoelectric conversion element 16 showing the position of a signal line (output signal line) that transmits a signal output from the pixel circuit 300 to another circuit. In the CMOS linear image sensor for the reduction optical system, the ratio of the area where the signal line (wiring) is arranged to the area where the PD is arranged may be larger than the CIS. The photoelectric conversion element 16 has a width in which the RGB signal lines output from the pixel circuit 300 are arranged to be equal to or smaller than the width of a separation band (pixel separation band) 40 that separates adjacent pixels (PD) in a pixel column. It is supposed to be.

  Specifically, as shown in FIG. 12A, the photoelectric conversion element 16 has a width W0 of the separation band 40 in the main scanning direction, an R signal line 42, a G signal line 44, and a B signal line. When W is a width in which 46 is arranged, W ≦ W0 is satisfied. Thereby, the photoelectric conversion element 16 is prevented from being limited in the opening of the PD by the signal line from the pixel circuit 300. Note that M1 to M3 in FIG. 12 each represent a wiring layer. That is, FIG. 12A shows an example in which the photoelectric conversion element 16 has a three-layer wiring structure. As described above, the output signal line for transmitting the signal output from the pixel circuit 300 to another circuit is formed in the wiring layer in which the separation band 40 for separating the PDs in the pixel column is not disposed, and the separation band 40. It is arranged in the range that overlaps.

  In addition, when a plurality of signal lines are arranged adjacent to each other, a false color may occur due to crosstalk between colors if the interval between the signal lines is small. Therefore, as shown in FIG. 12B, the photoelectric conversion element 16 may have signal lines arranged in different wiring layers for each pixel column. Thereby, the photoelectric conversion element 16 prevents crosstalk between colors due to the signal lines, and prevents the opening of the PD from being limited by the signal lines from the pixel circuit 300. It should be noted that the RGB signal lines do not necessarily have the same position in the main scanning direction at the center of the separation band 40 as shown in FIG. 12B. From the viewpoint, it is desirable to arrange as shown in FIG.

  FIG. 13 is a diagram showing an outline of the first embodiment (photoelectric conversion element 16 a) of the photoelectric conversion element 16. The photoelectric conversion element 16 is not limited to a signal line that transmits a signal output from the pixel circuit 300, but a control line (control signal line) that transmits a control signal for controlling the pixel circuit 300 may limit the opening of the PD. is there.

  In the photoelectric conversion element 16a, a control line for the pixel circuit 300 is disposed in a non-light receiving region such as the non-pixel region 30. This prevents the photoelectric conversion element 16a from restricting the opening of the PD by the control line to the pixel circuit 300.

  In FIG. 13, the control lines are indicated by three RS / T / VDD (power supply lines). However, since there are actually a plurality of control lines, the wiring space cannot be ignored. Therefore, the photoelectric conversion element 16a has a common control line to the pixel circuit 300 at least in the same pixel column. Thereby, in the photoelectric conversion element 16a, the scale of the control line is minimized and the opening of the PD is prevented from being restricted.

  Further, in the photoelectric conversion element 16a, a control line to the pixel circuit 300 is common between pixel columns (between RGB). As a result, the photoelectric conversion element 16a realizes simultaneous exposure (global shutter) in which the exposure timings are adjusted in RGB, thereby enabling to prevent color misregistration. In FIG. 13, it is possible to make exposure timings simultaneous by making the control lines common to RGB, but the control lines are configured independently of each other using RGB control signals at the same timing. The effect is the same.

  FIG. 14 is a diagram showing an outline of a second embodiment (photoelectric conversion element 16 b) of the photoelectric conversion element 16. FIG. 15 is a diagram illustrating a pixel configuration in units of columns of the photoelectric conversion element 16b illustrated in FIG. When the photoelectric conversion element 16 is a CMOS linear color image sensor, a logic circuit can be built in. Therefore, a variable gain amplifier (PGA; Programmable-Gain-Amplifier) or ADC (Analog-Digital-Converter) is provided in the subsequent stage of the pixel circuit 300. In some cases, high-precision and low-noise image reading is performed. In addition, the photoelectric conversion element 16 may include a PGA or an ADC for each pixel in order to further increase the speed, but in that case, the circuit scale becomes large.

  As shown in FIGS. 14 and 15, the photoelectric conversion element 16 b includes a pixel circuit 300 and an analog memory 302 (MEM, Cm) in each non-pixel region 30 for each pixel. The analog memory Cm is connected to the subsequent stage of the pixel circuit 300, and temporarily holds the output of the pixel circuit 300. The switch at the subsequent stage of the analog memory Cm is a pixel selection unit (S, Tr3), which is a selection switch for sequentially outputting RGB output to the PGA or ADC.

  Therefore, since the photoelectric conversion element 16b can once hold the signal output from the pixel circuit 300 in the analog memory Cm, it is possible to share the PGA and ADC that can be arranged in the subsequent stage of the pixel circuit 300. That is, the photoelectric conversion element 16b can perform processing by PGA or ADC serially, and can process each RGB signal independently by the same circuit, so that the circuit scale can be reduced. Since the photoelectric conversion element 16b includes a pixel selection unit and sequentially transmits RGB signals to other circuits in the subsequent stage, the signal readout line is common to RGB.

  FIG. 16 is a diagram illustrating an operation example of the photoelectric conversion element 16b. The operation of the pixel circuit 300 is the same as the operation shown in FIG. In the photoelectric conversion element 16b, the signal output from the pixel circuit 300 is temporarily held in the analog memory Cm ((*)) for each of RGB. Next, when the RGB pixel selection signal (S (*)) is sequentially turned ON, the signal held in the analog memory Cm ((*)) is read out to the RGB common signal readout line (SIG) and is not shown in the subsequent stage. Output to PGA or ADC.

  Further, in the case where correlated double sampling (CDS) is performed, the photoelectric conversion element 16b may hold a signal after RS is turned on (before T is turned on) as a reference level. However, in this case, the photoelectric conversion element 16b needs to further include an analog memory Cm for the reference level.

  Next, an image forming apparatus provided with an image reading apparatus having the photoelectric conversion element 16 will be described. FIG. 17 is a diagram illustrating an outline of an image forming apparatus 50 including an image reading device 60 having the photoelectric conversion element 16. The image forming apparatus 50 is, for example, a copying machine or an MFP (Multifunction Peripheral) having an image reading device 60 and an image forming unit 70.

  The image reading device 60 includes, for example, a photoelectric conversion element 16, an LED driver (LED_DRV) 600, and an LED 602. The LED driver 600 drives the LED 602 in synchronization with a line synchronization signal output from the timing control unit (TG) 160. The LED 602 irradiates the original with light. The photoelectric conversion element 16 receives reflected light from the document in synchronization with a line synchronization signal or the like, and a plurality of light receiving elements (PD) (not shown) generate electric charges and start accumulation. The photoelectric conversion element 16 performs AD conversion, parallel serial conversion, and the like, and then outputs image data to the image forming unit 70 through the LVDS 162.

  The image forming unit 70 includes a processing unit 80 and a printer engine 82, and the processing unit 80 and the printer engine 82 are connected via an interface (I / F) 84.

  The processing unit 80 includes an LVDS 800, an image processing unit 802, and a CPU 804. The CPU 804 controls each part of the image forming apparatus 50 such as the photoelectric conversion element 16. In addition, the CPU 804 (or the timing control unit 160) performs control so that each PD starts generating charges according to the amount of received light almost simultaneously.

  The LVDS 162 outputs, for example, image data of an image read by the image reading device 60, a line synchronization signal, a transmission clock, and the like to the LVDS 800 at the subsequent stage. The LVDS 800 converts received image data, a line synchronization signal, a transmission clock, and the like into parallel 10-bit data. The image processing unit 802 performs image processing using the converted 10-bit data, and outputs image data and the like to the printer engine 82. The printer engine 82 performs printing using the received image data.

16, 16a, 16b Photoelectric conversion element 30 Non-pixel region 40 Separation zone 50 Image forming device 60 Image reading device 70 Image forming unit 300 Pixel circuit 302 MEM, Cm (analog memory)
PD photodiode (light receiving element)
FD floating diffusion (charge-voltage converter)
SF source follower (transmitter)
Tr1 Reset unit Tr2 Transfer unit Tr3 Pixel selection unit

JP 2010-135464 A

Claims (14)

A plurality of light receiving elements that generate charges for each pixel according to the amount of light received;
A plurality of pixel circuits that operate to derive charges generated by the plurality of light receiving elements for each pixel from the plurality of light receiving elements, and
The plurality of light receiving elements are:
Arranged in the light receiving area to receive light from the outside,
The plurality of pixel circuits are
It is provided in a non-light-receiving area that does not receive light from the outside,
The sub-scanning width of the pixel region in which the light receiving element generates charge and the sub-scanning width of the non-pixel region in which the pixel circuit that operates so as to derive the generated charge is substantially equal. A characteristic photoelectric conversion element. Each of the pixel circuits
A transfer unit that transfers the charge generated by the light receiving element for each pixel;
A charge-voltage converter that converts the charge transferred by the transfer unit into a voltage;
A reset unit for resetting the electric potential of the charge-voltage conversion unit;
The photoelectric conversion element according to claim 1, further comprising: a transmission unit that transmits the voltage converted by the charge-voltage conversion unit to another circuit. The plurality of light receiving elements are:
One or more pixel rows are arranged in one direction for each color of light received,
The non-light receiving region is
The photoelectric conversion element according to claim 1, wherein the photoelectric conversion element is provided for each pixel column so as to be adjacent to the pixel column. The photoelectric conversion element according to claim 3, wherein a control signal line for transmitting a control signal for controlling the pixel circuit is common between the light receiving elements in the pixel column. The photoelectric conversion element according to claim 4, wherein the control signal line is common between the pixel columns. The photoelectric conversion element according to claim 4, wherein the control signal line is formed in the non-light-receiving region. An output signal line for transmitting a signal output from the pixel circuit to another circuit is formed in a wiring layer in which no separation band for separating the light receiving elements in the pixel column is arranged, and overlaps the separation band. It is arrange | positioned in the range. The photoelectric conversion element of any one of Claim 3 thru | or 6 characterized by the above-mentioned. The photoelectric conversion element according to claim 7, wherein the output signal line is formed in a different wiring layer for each pixel column. The output signal line is
The photoelectric conversion element according to claim 7, wherein the photoelectric conversion element is formed independently for each of the pixel circuits. The pixel circuit includes:
The photoelectric conversion element according to any one of claims 1 to 9, wherein a signal is output through an analog memory. The photoelectric conversion element according to any one of claims 1 to 10,
An image reading apparatus comprising: a control unit that controls the plurality of light receiving elements to start generating electric charges according to the amount of received light substantially simultaneously. An image reading apparatus according to claim 11,
An image forming apparatus comprising: an image forming unit that forms an image based on an output of the image reading apparatus. A step of generating a charge for each pixel according to the amount of light received by each of a plurality of light receiving elements arranged in a light receiving region that receives light from the outside;
The light receiving element receives light from the outside in which the sub-scanning width of the pixel area where the charge is generated is substantially equal to the sub-scanning width of the non-pixel area where the pixel circuit that operates to derive the generated charge is arranged. A step of deriving charges generated by each of the plurality of light receiving elements for each pixel from the plurality of light receiving elements by each of the plurality of pixel circuits provided in the non-light-receiving region,
An image reading method including:   A step of transmitting a signal output from each of the pixel circuits to another circuit by an output signal line formed independently for each of the pixel circuits, or a step of outputting a signal via an analog memory by each of the pixel circuits. The image reading method according to claim 13.

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