JP2007336519A - Solid-state image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image pickup device in simple configuration which reduces a pixel array pitch of one-dimensional pixel arrays and suppresses the occurrence of color displacement in a reproduced image. <P>SOLUTION: The solid-state image pickup device is provided with (n) one-dimensional pixel arrays for picking up a document image by relative movement of the one-dimensional pixel arrays and the document image in a scanning direction. The solid-state image pickup device includes: an image readout circuit, commonly provided for the one-dimensional pixel arrays, for performing a horizontal readout operation from the (n) one-dimensional pixel arrays with respect to image data acquired by sensing the document image, wherein a pixel array pitch of each of the (n) one-dimensional pixel arrays in the scanning direction is set to at least (n+1)/n times as large as pixel width of each of pixels constituting the one-dimensional pixel arrays in the scanning direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device, and more particularly to a color linear image sensor.

2. Description of the Related Art Conventionally, a solid-state imaging device of a CCD (Charge Coupled Device) linear image sensor has been used in document reading devices such as scanners, facsimiles, and copiers. Recently, color-compatible devices are becoming popular. In this regard, for example, a solid-state imaging device (color linear image sensor) in which a plurality of R, G, and B pixel rows, that is, a plurality of one-dimensional pixel rows, as disclosed in Patent Document 1, for example, is known. . When this solid-state imaging device is used in a document reading device or the like, a scanning operation is performed by mechanically moving the solid-state imaging device, the imaging optical system, or the document in the document reading device. At that time, when the pitch between a plurality of one-dimensional pixel rows is large, each pixel row is supposed to be sequentially read at the same position of the original image. The image of the position is read. As a result, when the solid-state imaging device is a color imaging device as described above, a noticeable color shift occurs in the reproduced image. Therefore, it is desirable that the pitch between the one-dimensional pixel columns is small.
JP 2002-142078 A JP-A-10-51602 SONY CX-PAL (vol. 65) p. 12-13

  However, since a transfer gate and a CCD shift register are necessarily required between the respective one-dimensional pixel columns in the conventional CCD linear image sensor, for example, it is composed of three or more one-dimensional pixel columns in Patent Document 1. As a result, in the case of a solid-state imaging device, the pixel column pitch of the one-dimensional pixel column is about four times as large as the pixel width (pixel column dimension) in the scanning direction of the one-dimensional pixel column. In addition, it is difficult to suppress the color shift.

  To deal with this problem, for example, Patent Document 2 and Non-Patent Document 1 have configurations in which the one-dimensional pixel columns are in contact with each other, that is, the pixel column pitch matches the pixel width in the scanning direction of the one-dimensional pixel column. A solid-state imaging device is disclosed. However, in the solid-state imaging device disclosed in Patent Document 2, it is impossible to realize a pixel column pitch that matches the pixel width in all three or more one-dimensional pixel columns. In addition, in the solid-state imaging device disclosed in Non-Patent Document 1, it is necessary to reduce the pixel width (pixel size) in the direction perpendicular to the scanning direction in at least one column. This will cause difficulty and decrease the sensitivity of document reading.

  The present invention has been made in view of the above circumstances, and is an image reading method in which the pixel row pitch between one-dimensional pixel rows is reduced and the occurrence of color misregistration in a reproduced image due to the influence of unevenness in scanning operation is suppressed. It is an object of the present invention to provide a solid-state imaging device having a simple configuration capable of.

  A solid-state imaging device according to the present invention is a solid-state imaging device that includes n one-dimensional pixel columns and images a document image by moving the original image relative to the scanning direction by using the one-dimensional pixel columns. An image readout circuit common to each one-dimensional pixel array for horizontally reading out image data obtained by imaging the original image from the pixel array, and each primary in the scan direction in the n one-dimensional pixel arrays The pixel column pitch, which is the pitch of the original pixel column, is at least (n + 1) / n times the pixel width, which is the width in the scanning direction, of the pixels constituting each one-dimensional pixel column. However, the symbol “n” indicates a natural number of 2 or more, and the symbol “/” indicates division.

  According to the above configuration, the solid-state imaging device is provided with n one-dimensional pixel rows that are picked up by relatively moving the document image in the scanning direction, and for horizontal reading with respect to the n one-dimensional pixel rows. Each one-dimensional pixel column is provided with a common image readout circuit, and the pixel column pitch of these one-dimensional pixel columns is at least (n + 1) / n times the pixel width.

  Further, in the above configuration, a control unit that controls an image reading operation by the image reading circuit is further provided, and the control unit is a distance in which one one-dimensional pixel row corresponds to a resolution pitch in the scan direction in the document image. The image reading circuit may be caused to execute an image reading operation so that the image reading operation of all the n one-dimensional pixel columns is completed during the time for moving the image.

  According to this, during the time during which a certain one-dimensional pixel column out of the n one-dimensional pixel columns moves a distance corresponding to the resolution pitch in the scanning direction in the document image under the control of the control unit. The image reading operation is executed by the image reading circuit so that the image reading operation of all the n one-dimensional pixel columns is completed.

  In the above configuration, the pixel column pitch may be not less than (n + 1) / n times the pixel width and less than 4 times.

  According to this, the pixel column pitch is not less than (n + 1) / n times and less than 4 times the pixel width.

  In the above configuration, the image readout circuit is connected to the image readout vertical signal line wired in the scan direction across the n one-dimensional pixel columns, and each pixel in each one-dimensional pixel column is connected. A circuit for reading out the pixel signals in time series may be used.

  According to this, the pixel signal of each pixel in each one-dimensional pixel column is sometimes transmitted by the image readout circuit connected to the vertical signal line for image readout wired in the scanning direction over n one-dimensional pixel columns. Read out to series.

  Further, in the above configuration, the pixels constituting the one-dimensional pixel column are configured such that a photoelectric conversion unit that generates a photocurrent by photoelectric conversion with respect to light incident on the pixels, and charges from the photoelectric conversion unit are accumulated. From the floating diffusion, a reset transistor for applying a reset bias to the floating diffusion, a transfer transistor for switching between transfer and non-transfer of the photocurrent to the floating diffusion, and the floating diffusion It is good also as a MOS type image pick-up element provided with the amplification transistor for amplifying the signal of (2), and the reading transistor for switching the reading of the signal amplified by the amplification transistor from the pixel, and non-reading (claim) 5).

  According to this, a pixel constituting the one-dimensional pixel column is a MOS type image pickup device including a photoelectric conversion unit, a floating diffusion, a reset transistor, a transfer transistor, an amplification transistor, and a readout transistor.

  In the solid-state imaging device according to the present invention, the pixel includes a photoelectric conversion unit that generates a photocurrent by photoelectric conversion with respect to incident light, and a peripheral circuit of the photoelectric conversion unit, and the pixels are arranged in one dimension. A solid-state imaging device that includes n one-dimensional pixel arrays and images a document image that is relatively moved in the scanning direction by using the one-dimensional pixel array, and from the n one-dimensional pixel arrays, the document image Each of the one-dimensional pixel columns for horizontally reading the image data obtained by imaging is provided with a common image reading circuit, and the pitch of each one-dimensional pixel column in the scan direction in the n one-dimensional pixel columns The pixel column pitch is at least (n + 1) / n times the photoelectric conversion unit width which is the width of the photoelectric conversion unit in the scanning direction. However, the symbol “n” represents a natural number of 2 or more, and the symbol “/” represents division (Claim 6).

  According to the above configuration, the pixel is a pixel including a photoelectric conversion unit that generates a photocurrent by photoelectric conversion with respect to incident light and a peripheral circuit of the photoelectric conversion unit, and the solid-state imaging device relatively moves the document image in the scan direction. And n one-dimensional pixel columns to be imaged, and a common image readout circuit for each one-dimensional pixel column for horizontal readout with respect to the n one-dimensional pixel columns. The pixel column pitch of the one-dimensional pixel column is at least (n + 1) / n times the width of the photoelectric conversion unit (photoelectric conversion unit width) in the pixel.

  Further, in the above configuration, a control unit that controls an image reading operation by the image reading circuit is further provided, and the control unit is a distance in which one one-dimensional pixel row corresponds to a resolution pitch in the scan direction in the document image. The image reading circuit may be caused to execute an image reading operation so that the image reading operation of all the n one-dimensional pixel columns is completed during the time for moving the image.

  According to this, during the time during which a certain one-dimensional pixel column out of the n one-dimensional pixel columns moves a distance corresponding to the resolution pitch in the scanning direction in the document image under the control of the control unit. The image reading operation is executed by the image reading circuit so that the image reading operation of all the n one-dimensional pixel columns is completed.

  In the above configuration, the pixel column pitch may be not less than (n + 1) / n times and less than 4 times the width of the photoelectric conversion unit.

  According to this, the pixel column pitch is set to (n + 1) / n times or more and less than 4 times the photoelectric conversion unit width.

  In the above configuration, the image readout circuit is connected to the image readout vertical signal line wired in the scan direction across the n one-dimensional pixel columns, and each pixel in each one-dimensional pixel column is connected. A circuit for reading out the pixel signals in a time series may be used.

  According to this, the pixel signal of each pixel in each one-dimensional pixel column is sometimes transmitted by the image readout circuit connected to the vertical signal line for image readout wired in the scanning direction over n one-dimensional pixel columns. Read out to series.

  Further, in the above configuration, the pixels constituting the one-dimensional pixel column are divided into the photoelectric conversion unit, a floating diffusion that accumulates charges from the photoelectric conversion unit and converts the charges into a voltage, and a reset for the floating diffusion. A reset transistor for applying a bias; a transfer transistor for switching between transfer and non-transfer of the photocurrent to the floating diffusion; an amplification transistor for amplifying a signal from the floating diffusion; and the amplification transistor A MOS type image pickup device including the peripheral circuit having a read transistor for switching between reading and non-reading of the signal amplified by the pixel (claim 10).

  According to this, a pixel constituting the one-dimensional pixel column is a MOS type image pickup device including a photoelectric conversion unit, a peripheral circuit having a floating diffusion, a reset transistor, a transfer transistor, an amplification transistor, and a readout transistor. The

  According to the solid-state imaging device of the first aspect, since the image readout circuit for performing horizontal readout from n one-dimensional pixel columns is provided in common to each one-dimensional pixel column, An image reading circuit (horizontal reading circuit) may not be provided for each pixel column, that is, only one n-dimensional pixel column is arranged and arranged, for example, a common image reading circuit is installed. Therefore, the pixel column interval (pixel column pitch) of the n one-dimensional pixel columns can be reduced, and the apparatus can have a simple configuration. In addition, since the pixel column pitch is at least (n + 1) / n times the pixel width, a non-pixel portion where no pixel exists in the pixel column pitch (1 / n times the pixel width (= (n + 1) / n times) -N / n times the width of the non-exposed portion; the inter-pixel space) is read by the image reading circuit using the timing of moving between the imaging pitches of the document image, in other words, For example, during the time when each one-dimensional pixel column moves a distance corresponding to the resolution pitch (= pixel width) in the scanning direction of the original image, the image reading circuit performs the image reading operation for all n one-dimensional pixel columns. Since the configuration to be completed can be realized, it is possible to realize image reading that suppresses the occurrence of color misregistration in the reproduced image due to the influence of unevenness in the scanning operation.

  According to the solid-state imaging device according to the sixth aspect, since the image readout circuit for performing horizontal readout from n one-dimensional pixel columns is provided as a common to each one-dimensional pixel column, An image reading circuit (horizontal reading circuit) may not be provided for each pixel column, that is, only one n-dimensional pixel column is arranged and arranged, for example, a common image reading circuit is installed. Therefore, the pixel column interval (pixel column pitch) of the n one-dimensional pixel columns can be reduced, and the apparatus can have a simple configuration. Further, since the pixel column pitch is at least (n + 1) / n times the photoelectric conversion unit width, a portion other than the photoelectric conversion unit in the pixel column pitch (1 / n times the photoelectric conversion unit width (= (n + 1)) / N times-n / n times); a portion having a width obtained by combining the peripheral circuit portion and the inter-pixel space) by the image reading circuit using the timing of moving between the imaging pitches of the document image. A configuration for performing image readout of the original pixel row, in other words, an image readout circuit during a time during which each one-dimensional pixel row moves a distance corresponding to the resolution pitch (= photoelectric conversion unit width) in the scan direction in the document image. Thus, it is possible to realize a configuration that completes the image reading operation of all n one-dimensional pixel columns, and therefore, it is possible to perform image reading that suppresses the occurrence of color misregistration in a reproduced image due to the influence of uneven feeding of the scanning operation. It can be.

  According to the solid-state imaging device according to claim 2, one one-dimensional pixel column out of the n one-dimensional pixel columns moves a distance corresponding to the resolution pitch (= pixel width) in the scanning direction in the document image. Since the image reading operation is performed so that the image reading operation of all the n one-dimensional pixel columns is completed during the time to perform the color shift in the reproduced image due to the influence of unevenness in the scanning operation. Can be suppressed.

  According to the solid-state imaging device according to claim 7, a distance corresponding to a resolution pitch (= photoelectric conversion unit width) in a scanning direction in a document image of a certain one-dimensional pixel row among n one-dimensional pixel rows. Since the image reading operation is performed so that the image reading operation of all the n one-dimensional pixel columns is completed during the time of moving the image, in the reproduced image due to the influence of the feeding operation unevenness, etc. The occurrence of color misregistration can be suppressed.

  According to the solid-state imaging device according to claim 3, the pixel column pitch is not less than (n + 1) / n times the pixel width and less than four times, that is, the upper limit value of the pixel column pitch is four times the pixel width. By doing so, it is possible to reliably prevent the color shift in the reproduced image from becoming prominent due to the influence of unevenness in the scanning operation.

  According to the solid-state imaging device according to claim 8, the pixel column pitch is not less than (n + 1) / n times and less than four times the photoelectric conversion unit width, that is, the upper limit value of the pixel column pitch is set to the photoelectric conversion unit width. By setting the number to 4 times, it is possible to reliably prevent the color shift in the reproduced image from becoming prominent due to the influence of unevenness in the scanning operation.

  According to the solid-state imaging device according to claim 4 and claim 9, since the pixel signal of each pixel in each one-dimensional pixel column is read in time series by the image reading circuit, the image reading having such a configuration is performed. Using a circuit and a configuration in which the pixel column pitch is at least (n + 1) / n times the pixel width (photoelectric conversion unit width), the distance corresponding to the resolution pitch in the scanning direction in the original image is determined for each one-dimensional pixel column. It is possible to easily realize a configuration for completing the image reading operation for all n one-dimensional pixel columns during the moving time.

  According to the solid-state imaging device according to claims 5 and 10, each pixel of the one-dimensional pixel column includes a photoelectric conversion unit, a floating diffusion, a reset transistor, a transfer transistor, an amplification transistor, and a readout transistor. For example, a pixel for performing horizontal readout from a one-dimensional pixel column because it is a MOS type image pickup device including a conversion unit, a peripheral circuit having a floating diffusion, a reset transistor, a transfer transistor, an amplification transistor, and a readout transistor No transfer gate or CCD shift register is required in the case of a CCD image sensor (horizontal readout using an image readout circuit common to the one-dimensional pixel array is possible by the XY address system). The pixel column spacing can be reduced, And it can be a device with a simple configuration.

  FIG. 1 is a schematic configuration diagram of a linear sensor which is an example of a solid-state imaging device according to the present embodiment. As shown in FIG. 1, the linear sensor 1 includes a sensor unit 2, a vertical scanning circuit 3, a horizontal scanning circuit 4, and a readout circuit 5. The sensor unit 2 is composed of a plurality of pixels 21 (pixels), and performs photoelectric conversion to an image signal according to the amount of light of the subject light image and outputs the image signal. The sensor unit 2 includes a plurality of R (Red), G (Green), and B (Blue) color sensor arrays (pixel columns; one-dimensional pixel columns) in which a plurality of pixels 21 are linearly arranged in one column. That is, an R sensor array 22, a G sensor array 23, and a B sensor array 24 are provided. The R, G, and B sensor arrays are each provided with R, G, and B color filters (not shown) that transmit light of each color on the light receiving surface of the pixel 21.

  The vertical scanning circuit 3 is a so-called vertical shift register that performs vertical scanning with respect to the sensor unit 2, and sequentially scans the row selection signal lines 25 corresponding to the R, G, and B sensor arrays 22 to 24. The horizontal scanning circuit 4 is a so-called horizontal shift register that performs horizontal scanning with respect to the sensor unit 2, and a vertical signal line 26 (column selection signal line; output signal) corresponding to each pixel 21 of the R, G, B sensor arrays 22 to 24. Line) sequentially.

  The readout circuit 5 outputs an image signal (photoelectric conversion signal) derived from each pixel 21 of the R, G, B sensor arrays 22 to 24 to the output signal line 26 for each pixel according to horizontal scanning by the horizontal scanning circuit 4. It is a circuit for sequentially reading out, and is a horizontal reading circuit that performs so-called horizontal reading. For example, one reading circuit 5 is provided for the sensor unit 2 and is a common reading circuit for the R, G, and B sensor arrays 22 to 24 (all pixel columns). The read circuit 5 includes a constant current load 51, a signal sample hold circuit 52, a noise sample hold circuit 53, and an amplifier 54 arranged for each vertical signal line 26. The constant current load 51 includes a load transistor Qa that functions as a so-called electronic load by applying a load voltage (signal VD) to a gate. The signal VD is also used to perform a potential operation so as to be adjusted to an operation range of a source follower amplifier described later. A signal VPS indicates a voltage applied to the source of the load transistor Qa.

  The signal sample hold circuit 52 samples (samples) a signal (image signal) as an input analog signal and temporarily holds this value. The signal sample and hold circuit 52 includes a signal sample and hold switch S1, a signal sample and hold capacitor C1 (capacitor C1), and the like, and the signal sample and hold capacitor C1 is charged and charged in accordance with the on and off of the signal sample and hold switch S1. The signal sample hold function is realized by holding and discharging the potential. The noise sample hold circuit 53 samples input noise (noise signal) and temporarily holds this value. The noise sample and hold circuit 53 includes a noise sample and hold switch S2, a noise sample and hold capacitor C2 (capacitor C2), and the like. The noise sample and hold capacitor C2 is charged and charged in accordance with the on / off state of the noise sample and hold switch S2. The noise sample hold function is realized by holding and discharging the potential.

  The amplifier 54 takes a difference between the image signal obtained by the sample hold and the noise signal (for example, subtracts the noise signal from the signal signal), and resets by the reset gate (transistor T11) in each pixel of the sensor unit 2. An image signal from which the variation of the FD potential is removed is obtained.

  FIG. 2 shows an example of the circuit configuration of each pixel 21 in the sensor unit 2. The pixel 21 includes a photodiode PD1, transistors T10 to T13 as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), and FD (Floating Diffusion). Here, N-channel MOSFETs are employed as the transistors T10 to T13. VDD, φRSB, φRST, φTX, and φV indicate signals (voltages) for the respective transistors, and GND indicates ground.

  The photodiode PD1 is a photoelectric conversion unit (photosensitive unit), and generates an electric signal corresponding to the amount of incident light from the subject, that is, a photocurrent IPD1. The transistor T12 forms a source follower amplifier (amplifier circuit) for a source follower amplification in combination with the constant current load 51, and amplifies a voltage V1OUT described later. The transistor T13 is a signal readout transistor that operates as a switch that is turned on and off in accordance with a voltage (signal φV) applied to the gate. The source of the transistor T13 is connected to the vertical signal line 26. When the transistor T13 is turned on, the current amplified by the transistor T12 is led to the vertical signal line 26 as an output current. The transistor T10 operates as a switch that is turned on and off in accordance with a voltage applied to the gate of the transistor, and is generated in the photodiode PD1 in response to on / off switching depending on the level of the gate potential. This is a so-called transfer gate that switches between transfer and non-transfer of the photocurrent IPD1 (charge) to the FD.

  The photocurrent IPD1 generated in the photodiode PD1 flows through the parasitic capacitance of the photodiode PD1, the charge is accumulated, and a voltage corresponding to the amount of accumulated charge is generated. At this time, if the transistor T10 is in an on state, the charge (negative charge) accumulated in the parasitic capacitance moves toward the FD. The FD is a charge holding unit that temporarily holds this charge, and plays a role of a so-called capacitor that changes the held charge into a voltage. The transistor T11 (reset gate transistor) switches between application and non-application of a reset bias to the FD according to on / off switching depending on the gate voltage of the transistor.

  FIG. 3 is an example of a timing chart relating to the imaging operation of the pixel 21, and in particular, R, G, and V by vertical scanning after charge accumulation is completed during a horizontal blank period (or within a column selection period by the horizontal scanning circuit 4). The timing chart regarding the signal read-out (charge sweep-out) operation | movement of each pixel of the B sensor arrays 22-24 is shown. Here, due to the polarity of the N-channel MOSFET, it is turned on at Hi (high) and turned off at Lo (low). As shown in the figure, the signal φRST is set to Hi at the timing indicated by reference numeral 201, and then the sample hold control signal φS2 for the noise sample-hold switch S2 is set to Hi at the timing indicated by reference numeral 202, whereby the noise signal is vertical. The noise signal (noise level) is sampled and held by the noise sample hold circuit 53 by reading it out to the signal line 26. Next, the signal φTX is set to Hi at the timing indicated by reference numeral 203, and then the sample hold control signal φS1 for the signal sample / hold switch S1 is set to Hi at the timing indicated by reference numeral 204, whereby the image signal is transferred to the vertical signal line 26. The image signal (signal level) is sampled and held by the read and signal sample and hold circuit 52.

  By the way, the linear sensor 1 includes a main control unit that controls the entire operation of the linear sensor 1. Specifically, the main control unit includes a ROM that stores various control programs, a RAM that temporarily stores various data, and a central processing unit (CPU) that reads and executes control programs from the ROM. Thus, the operation of each functional unit such as the sensor unit 2 and the vertical and horizontal scanning circuits 3 and 4 or the reading circuit 5 in the linear sensor 1 is controlled. FIG. 4 is a block diagram showing a scanning operation in the main control unit (referred to as main control unit 100). The main control unit 100 includes a sensor control unit 101, a scan drive control unit 102, a vertical scanning control unit 103, a horizontal scanning control unit 104, and a readout control unit 105.

  The sensor control unit 101 controls the imaging operation of each of the R, G, and B sensor arrays 22 to 24 in the sensor unit 2, and outputs various signals such as VDD, φRSB, φRST, φTX, and φV to each pixel. To do. The scan drive control unit 102 scans and moves the linear sensor 1 or the imaging optical system with respect to the document or reads the document with respect to the linear sensor 1 or the imaging optical system so that the sensor unit 2 can read the document image. Driving for moving (scanning driving) is performed. The imaging optical system is an optical system (lens, mirror, etc.) for forming a subject light image from a document on the light receiving surfaces of the R, G, and B sensor arrays 22 to 24. 1 may be provided with this imaging optical system. The vertical scanning control unit 103 controls the vertical scanning operation for the R, G, and B sensor arrays 22 to 24 by the vertical scanning circuit 3. The horizontal scanning control unit 104 controls the horizontal scanning operation for the R, G, and B sensor arrays 22 to 24 by the horizontal scanning circuit 4. The read control unit 105 controls the image read operation from the R, G, B sensor arrays 22 to 24 by the read circuit 5. Details of the image reading operation by the reading control unit 105 will be described later.

  In the above configuration, in the linear sensor 1, the R, G, and B sensor arrays 22 to 24 are sequentially selected by the vertical scanning circuit 3, and the image signals are extracted line-sequentially by the common readout circuit 5 and the horizontal scanning circuit 4. . The linear sensor 1 is a so-called MOS type (for example, CMOS type) solid-state imaging device, and each pixel is selected by the XY addressing method (XY scanning method) by the vertical scanning circuit 3 and the horizontal scanning circuit 4. The image signal of each pixel can be taken out.

  By the way, in this embodiment, although it has the main feature points about the structure of the sensor part 2 and the scanning operation | movement by this sensor part 2, this feature point is demonstrated below. FIG. 5 is a schematic diagram conceptually illustrating a configuration example of the sensor unit 2. As shown in the figure, the pitch of each R, G, B sensor array 22-24 in the scanning direction SD (direction perpendicular to the pixel array direction (longitudinal direction) of the sensor array; vertical scanning direction) (this is the pixel column pitch). P) is 4/3 times the width of the pixel 27 in the scanning direction SD of the R, G, B sensor arrays 22 to 24 (this is expressed as the pixel width W). In other words, the pixel column pitch P is four times the length obtained by dividing the pixel width W into three equal parts (the length of “1/3” when the pixel width W is “1”). In general, the pixel column pitch P is (n + 1) / n times the pixel width W (n: a natural number of 2 or more). This “n” corresponds to the number of columns of the sensor array (here, the number of columns is the same as the number of types of colors (three types of RGB)). Here, since there are three rows of R, G, and B sensor arrays 22 to 24, n = 3. However, n is set to 2 or more because the scan operation method according to the present embodiment is applied when the sensor array has a plurality of columns, that is, two or more columns. The pixel 27 corresponds to the pixel 21, and a spatial gap (referred to as a space 28) indicated by reference numeral 28 exists between the pixels 27 of the R, G, and B sensor arrays 22 to 24. The total length of the space 28 in the scanning direction SD and the pixel width W is the pixel column pitch P.

  A document image is scanned by the sensor unit 2 having such a configuration. This scanning operation will be described with reference to FIGS. FIG. 6 shows an example of the relationship between the accumulation time (exposure time) and readout time in each of the R, G, B sensor arrays 22 to 24 (RGB pixels) in one frame (one frame time) of the scanning operation. It is a timing chart which shows. FIG. 7 is a schematic diagram for conceptually explaining the scanning operation by the R, G, B sensor arrays 22 to 24. Specifically, FIG. 7 shows pixels for one column in the scan direction SD of the R, G, B sensor arrays 22 to 24, for example, the leftmost pixel (R, G) of the sensor unit 2 shown in FIG. , B represents a pixel column composed of three pixels 27 and a space 28 (which is expressed as a pixel column SE), for example, moves from the state (1) to the state (4) in the scan direction with time. ing. Here, a case where the pixel column pitch P is 4/3 times the pixel width W is shown.

  In FIG. 6, first, at time t1, the accumulation (charge accumulation) operation continued from time t01 in the R sensor array 22 (represented as an R pixel column here) is completed, and the accumulated information (images) of the R pixel column is terminated. Reading of information) is started. The movement position of the pixel row SE at time t1 is shown in the state (1) in FIG. Here, assuming that the reading pitch PR is the pitch at which the document image is read by the sensor unit 2, in the state (1), for example, the R pixel of the pixel row SE is a portion having a width indicated by the reading pitch PR as indicated by reference numeral 301. Are located at the same position as the original image position (represented as the imaging pitch position), that is, the overlapping position. The readout operation in the R pixel column started from time t1 ends at time t2. From time t1 to time t2, as described above, since there is one readout circuit 5, signals from other pixel columns cannot be read out simultaneously. Note that the readout operation of the accumulated information of the R pixel column does not necessarily have to be performed continuously during the period from the time t1 to the time t2. In short, it is only necessary that the readout operation is performed within the period.

  At time t2, the accumulation operation that has been continued from time t02 in the G sensor array 23 (represented as a G pixel column) is completed, and the operation for reading the accumulated information of the G pixel column is started (this G pixel column). Is continued until time t3 described later). The movement position of the pixel row SE at time t2 is shown in state (2). In this state (2), as indicated by reference numeral 302, until the G pixel in the pixel row SE becomes the same position as the position of the R pixel (R pixel row) relative to the imaging pitch position at the time t1, that is, The entire linear sensor 1 is scanned and moved from the position of the state (1) by a distance of 1/3 of the pixel width W indicated by reference numeral 311 (a distance of 1/4 of the pixel column pitch P).

  Next, at time t3, the accumulation operation that has been continued from time t03 in the B sensor array 24 (represented as a B pixel column) ends, and the operation for reading the accumulated information of the B pixel column is started (this operation). The readout operation of the B pixel column is continued until time t4 described later). The movement position of the pixel row SE at time t3 is shown in state (3). In this state (3), as indicated by reference numeral 303, until the B pixel in the pixel row SE is at the same position as the position of the R pixel (R pixel row) relative to the imaging pitch position at time t1, that is, The entire linear sensor 1 is scanned and moved from the position of the state (2) by a distance of 1/3 of the pixel width W indicated by reference numeral 312.

  Further, at time t4, the accumulation operation continued from time t1 in the R pixel column is finished again, and the readout operation of the accumulated information in the R pixel column is started. The movement position of the pixel row SE at time t3 is shown in state (4). In this state (4), as indicated by reference numeral 304, the R pixel is the distance corresponding to 1/3 of the pixel width W indicated by reference numeral 313 from the position of the state (3), that is, the R pixel is in the state (1). The entire linear sensor 1 is scanned and moved to the imaging pitch position 322 next to the imaging pitch position 321 that has been imaged in FIG. Thereafter, similarly, the entire linear sensor 1 is scanned and moved by a distance of 1/3 of the state (5), (6), (7)... And the pixel width W, and G → B → R → G → B. The readout operation for each color is performed at the timing when the pixels of each color (referred to as color pixels) coincide with the imaging pitch position. Then, the R pixel further advances from the imaging pitch position 322 to the next imaging pitch position, and similarly, R, G, and B read operations are sequentially performed. In this way, the series of scanning operations are executed over the entire document image. Note that the time from time t01 to time t1, that is, the accumulation time of a certain color pixel, is the time for the color pixel, for example, the R pixel in the pixel row SE to move from a certain imaging pitch position to the next imaging pitch position. Therefore, the time intervals at times t01, t02, t03, and t1 are the same as the time intervals at times t1, t2, t3, and t4.

  In this way, the time (the time from time t1 to time t4) that the R pixel row moves from the imaging pitch position that was imaged at time t1 to the imaging pitch position that is imaged at time t4, that is, the resolution pitch (resolution) in the scan direction. ) During the time of moving the distance corresponding to (), the readout operation for all the R, G, and B color pixel columns is completed. In other words, the time corresponding to 1/3 of the accumulation time of one pixel column (corresponding to the time t4-t1) is allocated to the readout time of each R, G, B pixel column. As described in the configuration of the sensor unit 2, the pixel columns of the respective colors are arranged on the imaging surface of the sensor unit 2 with a space of 1/3 of the pixel width W (scan direction pixel column dimension). That is, by arranging the pixel row pitch P to be 4/3 times the pixel width W, this scanning operation can be performed. When the pixel column pitch P is made shorter than 4/3 times the pixel width W, that is, the width in the scanning direction in the space 28 between the pixels 27 in the pixel column SE is 1 / n times the pixel width W. If it is narrower, the R, G, B sensor arrays 22 to 24 (each pixel column) are displaced from each other, that is, the color pixels are not aligned with the imaging pitch position in order as described above, and color misregistration occurs. As a result, the quality of the reproduced image data deteriorates.

  In the above embodiment, as shown in FIG. 5, the pixel column pitch is at least (n + 1) / n times the “pixel width”. However, the present invention is not limited to this, and the pixel column pitch is set to “photoelectric conversion unit width”. It may be configured to be at least (n + 1) / n times "". That is, in FIG. 8, the pixel 27 is actually provided with a photoelectric conversion unit 271 and a peripheral circuit 272 as shown by a pixel 27 ′, and the pixel 27 ′ is arranged in one dimension. This is a one-dimensional pixel column (R, G, and B sensor arrays 22, 23, and 24; R, G, and B pixel columns). The photoelectric conversion unit 271 corresponds to the photodiode PD1, and the peripheral circuit 272 is a circuit unit arranged, for example, in an L shape around the photoelectric conversion unit 271, and includes the transistors T10 to T13 and the FD. It is a circuit including. In this configuration, the pixel column pitch P may be at least (n + 1) / n times (here, 4/3 times) the width of the photoelectric conversion unit 271 in the scanning direction SD (referred to as photoelectric conversion unit width T). However, even in this modification, the document image scanning operation is the same as in the above embodiment. For example, in the description of FIGS. 6 and 7, “pixel width W” is replaced with “photoelectric conversion unit width T”. Think about it.

  In this case, a portion other than the photoelectric conversion unit 271 in the pixel column pitch P (a portion having a width of 1 / n times (= (n + 1) / n times−n / n times) the photoelectric conversion unit width T) in the scanning direction SD. A readout circuit using the timing at which the width of the peripheral circuit 272 and the width of the space 28 ′ between the pixels 27 ′ (the width indicated by the symbol Y) moves between the imaging pitches (reading pitches) of the document image. 5 reads out the image of each one-dimensional pixel column.

  The configuration (shape) of the photoelectric conversion unit 271 and the peripheral circuit 272 of the pixel 27 ′ is not limited to the above. For example, as illustrated in FIG. 9A, the peripheral circuit 272 is positioned relative to the position illustrated in FIG. Configuration located on the opposite side in the scanning direction SD (may be located on the opposite side in the direction of arrow A with respect to the position shown in FIG. 9A), or peripheral circuit 272 as shown in FIG. 9B May be a straight line instead of the L-shape, and this may be arranged at one or both ends in the scanning direction SD of the photoelectric conversion unit 271. A peripheral circuit 272 that surrounds the entire circumference of the photoelectric conversion unit 271 may be used. In short, it is sufficient that the peripheral circuit 272 has a width in the scan direction SD. However, when the peripheral circuit 272 is arranged so as to surround both ends of the photoelectric conversion unit 271 in the scanning direction SD or the entire circumference of the photoelectric conversion unit 271, the width indicated by the symbol Y (the photoelectric conversion unit 271 in the scanning direction SD). The width of the space 28 ′ and the width of the two peripheral circuits 272 in the adjacent image 27 ′ of each color.

  As described above, according to the linear sensor 1 (solid-state imaging device) according to this embodiment, the n linear one-dimensional pixel array (R, G, B sensor arrays 22 to 24) and a readout circuit 5 common to the one-dimensional pixel column for horizontal readout for each one-dimensional pixel column, and a pixel column pitch of the one-dimensional pixel column P is at least (n + 1) / n times the pixel width W.

  Thus, since the readout circuit 5 for performing horizontal readout from n one-dimensional pixel columns is provided as a common circuit for each one-dimensional pixel column, the readout circuit 5 ( Horizontal readout circuit) may not be provided, that is, as shown in FIG. 1, only n one-dimensional pixel columns are arranged together, and for example, a common readout circuit 5 is installed. Therefore, the pixel column pitch P of the n one-dimensional pixel columns can be reduced, and the apparatus can have a simple configuration. In addition, since the pixel column pitch P is at least (n + 1) / n times the pixel width W, a non-pixel portion where no pixel exists in the pixel column pitch P (1 / n times the pixel width (= (n + 1)) / N times-n / n times) width of the non-exposed part; the space 28) between the pixels 27 is used by the readout circuit 5 to take advantage of the timing at which the space 28) moves between the imaging pitches of the original image. A configuration in which reading is performed, in other words, during the time during which each one-dimensional pixel column moves a distance corresponding to the resolution pitch in the scanning direction (imaging direction) in the original image, the reading circuit 5 performs n one-dimensional pixel columns. Since a configuration that completes all image reading operations can be realized, it is possible to realize image reading that suppresses the occurrence of color misregistration in a reproduced image due to the influence of unevenness in scanning operation.

  In addition, according to the linear sensor 1 (solid-state imaging device) (see FIG. 8) according to another embodiment, the photoelectric conversion unit 271 in which the pixel 27 ′ generates a photocurrent by photoelectric conversion with respect to incident light, and the photoelectric conversion unit 271. The peripheral sensor 272 includes a peripheral circuit 272, and the linear sensor 1 includes n one-dimensional pixel rows that are picked up by relatively moving the document image in the scan direction. A common readout circuit 5 is provided for each one-dimensional pixel column for horizontal readout with respect to one one-dimensional pixel column, and the pixel column pitch of these one-dimensional pixel columns is the width of the photoelectric conversion unit 271 in the pixel 27 ′ ( The size is at least (n + 1) / n times that of the photoelectric conversion unit T).

  Thus, since the readout circuit 5 for performing horizontal readout from n one-dimensional pixel columns is provided as a common circuit for each one-dimensional pixel column, the readout circuit 5 ( The horizontal readout circuit) may not be provided, that is, only one n-dimensional pixel column may be collectively arranged, and for example, a common readout circuit 5 may be installed. The pixel column interval (pixel column pitch) of the one-dimensional pixel column can be reduced, and the apparatus can be configured simply. In addition, since the pixel column pitch is at least (n + 1) / n times the photoelectric conversion unit width T, a portion other than the photoelectric conversion unit 271 in the pixel column pitch (1 / n times the photoelectric conversion unit width T (= (N + 1) / n times-n / n times); a portion having a width obtained by combining the peripheral circuit 272 and the inter-pixel space 28 ') using the timing of moving between the imaging pitches of the document image. A configuration in which an image of each one-dimensional pixel column is read by the readout circuit 5, in other words, a time during which each one-dimensional pixel column moves a distance corresponding to the resolution pitch (= photoelectric conversion unit width T) in the scanning direction in the document image In the meantime, since the readout circuit 5 can complete the image readout operation of all n one-dimensional pixel columns, it is possible to suppress the occurrence of color misregistration in the reproduced image due to the influence of unevenness in the scanning operation. Image reading has can be achieved.

  Further, under the control of the reading control unit 105 (main control unit 100), one of the n one-dimensional pixel columns has a resolution pitch (= pixel width W or The image reading operation is executed by the reading circuit 5 so that the image reading operation of all the n one-dimensional pixel columns is completed during the time of moving the distance corresponding to the photoelectric conversion unit width T). Therefore, it is possible to suppress the occurrence of color misregistration in the reproduced image due to the influence of uneven feeding of the scanning operation.

  Further, the pixel column pitch P is not less than (n + 1) / n times and less than four times the pixel width W (photoelectric conversion unit width T), that is, the upper limit value of the pixel column pitch P is set to the pixel width W ( By setting 4 times the photoelectric conversion portion width T), it is ensured that the pixel column pitch P becomes 4 times or more, and color misregistration in the reproduced image due to the influence of scanning operation unevenness becomes remarkable. Can be prevented.

  Further, the readout circuit 5 is connected to an image readout vertical signal line 26 wired in the scan direction over n one-dimensional pixel columns, and the pixel signal (image signal) of each pixel 21 in each one-dimensional pixel column. And the noise signal) are read out in time series, that is, the readout circuit 5 reads out the pixel signals of the pixels 21 in the one-dimensional pixel column in time series. Using the circuit 5 and a configuration in which the pixel column pitch P is at least (n + 1) / n times the pixel width W (photoelectric conversion unit width T), each one-dimensional pixel column has a resolution pitch in the scanning direction of the document image. It is possible to easily realize a configuration for completing the image reading operation of all n one-dimensional pixel columns during the time of moving the corresponding distance.

  Further, each pixel 21 of the one-dimensional pixel column includes a photoelectric conversion unit (photodiode PD1), a floating diffusion (FD), a reset transistor (transistor T11), a transfer transistor (transistor T10), an amplification transistor (transistor T12), and a readout transistor. (Transistor T13; row selection transistor) or a MOS type image pickup device including a photoelectric conversion unit 271, a peripheral circuit 272 including a floating diffusion, a reset transistor, a transfer transistor, an amplification transistor, and a readout transistor. This eliminates the need for a transfer gate and a CCD shift register for performing horizontal readout from a one-dimensional pixel array, for example, when the pixel is a CCD image sensor (according to the XY address method). Horizontal read using a common reading circuit 5 to the original pixel column is possible), it is possible to reduce the pixel column pitch P of the one-dimensional pixel row, also can be an apparatus with simple structure.

It should be noted that various configurations can be added or changed without departing from the spirit of the present invention, and for example, the following modifications can be taken.
(A) In the above-described embodiment, the linear sensor 1 is configured to include three sensor arrays of R, G, and B colors. The sensor array may be provided.

  (B) In the above embodiment, the pixel column pitch P is (n + 1) / n times as large as the pixel width W (or photoelectric conversion unit width T), but is not limited to (n + 1) / n times. Alternatively, the size may be (n + 1) / n times or more. In this case, the upper limit value of the pixel column pitch P is preferably less than, for example, four times the pixel width W (photoelectric conversion unit width T) ((n + 1) / n ≦ pixel width W of the pixel column pitch P (photoelectric conversion unit) Magnification <4) for width T). Specifically, when the pixel column pitch P in the above embodiment is 4/3 times the pixel width W (photoelectric conversion unit width T), the pixel column pitch P is 4/3 times larger than the pixel width P. Even if the G, B, and B sensor arrays 22 to 24 are arranged, each sensor array of each color is sequentially captured in the same manner as the sensor arrays of the respective colors are sequentially matched with the reference numerals 301, 302, and 303 in FIG. It is possible to perform a scanning operation that matches the pitch position. In this case, each reading pitch PR in the document image is larger than the pixel width W (photoelectric conversion unit width T) unlike the case of FIG. 7, and a reading pitch larger than the pixel width W (photoelectric conversion unit width T) is set. For example, the image reading operation for all of the R, G, and B sensor arrays 22 to 24 is completed during the time during which the R pixels of the R sensor array 22 scan and move (however, the high reading pitch means that the resolution is high) Indicating a large pitch).

  In this case, if the switching frequency of the horizontal scanning circuit 4 and the readout circuit 5 is set to the same frequency as that when the pixel column pitch P is 4/3 times the pixel width W (photoelectric conversion unit width T), as a whole A high-speed scanning operation is executed. In this case, the entire scanning operation time is set to be the same time as when the pixel row pitch P is 4/3 times the pixel width W (photoelectric conversion unit width T) (that is, the low-speed scanning with respect to the high-speed scanning). If so, the scanning operation is executed with the switching frequency of the horizontal scanning circuit 4 and the reading circuit 5 lowered. However, when the pixel column pitch P is four times or more the pixel width W (photoelectric conversion unit width T), the color shift of the reproduced image due to the influence of unevenness of scanning operation becomes significant, and therefore the pixel column pitch P is the pixel. It is desirable that the width be less than four times the width W (photoelectric conversion portion width T).

  (C) In the above embodiment, the readout circuit common to each of the R, G, B sensor arrays 22 to 24 is configured to include one readout circuit 5 as shown in FIG. A configuration including a plurality of readout circuits may be employed. For example, as shown in FIG. 10, vertical signal lines 26 ′ are alternately drawn from the R, G, B sensor arrays 22 ′ to 24 ′ for each pixel to the R sensor array side and the B sensor array side (R sensor array For example, two readout circuits 401 and 402 may be provided so as to correspond to the extracted vertical signal line 26 ′. Also in this case, the two readout circuits 401 and 402 are readout circuits (horizontal readout circuits) common to the R, G and B sensor arrays 22 'to 24', respectively.

  (D) In the above embodiment, all three pixel columns of the R, G, and B sensor arrays are arranged in the same positional relationship (equally spaced from each other). For example, one pixel column among the plurality of pixel columns The present invention can be applied even when is arranged at a position different from other pixel columns.

  (E) In the above embodiment, an N-channel MOSFET is employed in each pixel of the sensor unit 2, but a P-channel MOSFET may be employed.

It is a schematic block diagram of the linear sensor which is an example of the solid-state imaging device which concerns on this embodiment. It is a figure which shows an example of the circuit structure of each pixel in the sensor part of the said linear sensor. It is a figure which shows an example of the timing chart regarding the imaging operation of the said pixel. It is a block block diagram regarding the scanning operation of the main control part. It is a schematic diagram which shows notionally one structural example of the said sensor part. It is a timing chart which shows an example of the relationship between the accumulation | storage time (exposure time) in each R, G, B sensor array in 1 frame of scanning operation | movement, and reading time. It is a schematic diagram conceptually explaining a scanning operation by an R, G, B sensor array. It is a schematic diagram for demonstrating one modification regarding the scanning operation | movement of a linear sensor. It is a schematic diagram for demonstrating one modification regarding the scanning operation | movement of a linear sensor. It is a mimetic diagram for explaining one modification of a linear sensor.

Explanation of symbols

1 Linear sensor (solid-state imaging device)
2 Sensor unit 22 R sensor array (one-dimensional pixel array)
23 G sensor array (one-dimensional pixel array)
24 B sensor array (one-dimensional pixel array)
21, 27, 27 ′ pixels (MOS-type image sensor)
25 row selection signal line 26 vertical signal line 271 photoelectric conversion unit 272 peripheral circuit 28, 28 'space 3 vertical scanning circuit 4 horizontal scanning circuit 5 reading circuit (image reading circuit)
51 Constant Current Load 52 Signal Sample Hold Circuit 53 Noise Sample Hold Circuit 54 Amplifier 100 Main Control Unit 105 Read Control Unit (Control Unit)
P Pixel row pitch W Pixel width PR Reading pitch (distance corresponding to resolution pitch)
SE pixel row T photoelectric conversion part width

Claims (10)

A solid-state imaging device that includes n one-dimensional pixel columns and images a document image by relatively moving the original image in the scan direction using the one-dimensional pixel columns,
An image reading circuit common to each one-dimensional pixel column for horizontally reading image data obtained by imaging the original image from the n one-dimensional pixel columns;
A pixel column pitch which is a pitch of each one-dimensional pixel column in the scan direction in the n one-dimensional pixel columns is at least (n + 1) of a pixel width which is a width in the scan direction of pixels constituting each one-dimensional pixel column. ) / N times, a solid-state imaging device.
However, the symbol “n” indicates a natural number of 2 or more, and the symbol “/” indicates division. A controller for controlling an image reading operation by the image reading circuit;
The controller is
The image reading is performed so that the image reading operation of all the n one-dimensional pixel columns is completed during a time in which one one-dimensional pixel column moves a distance corresponding to the resolution pitch in the scan direction in the document image. The solid-state imaging device according to claim 1, wherein an image reading operation is executed by a circuit.   3. The solid-state imaging device according to claim 1, wherein the pixel column pitch is not less than (n + 1) / n times and less than 4 times the pixel width. The image readout circuit includes:
A circuit connected to the vertical signal lines for image readout that are wired in the scan direction over the n one-dimensional pixel columns, and for reading out the pixel signals of the respective pixels in each one-dimensional pixel column in time series. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is provided. The pixels constituting the one-dimensional pixel row are
A photoelectric conversion unit that generates a photocurrent by photoelectric conversion with respect to light incident on the pixel;
A floating diffusion for accumulating the charge from the photoelectric conversion unit and converting the charge into a voltage;
A reset transistor for applying a reset bias to the floating diffusion;
A transfer transistor for switching between transfer and non-transfer of the photocurrent to the floating diffusion; and
An amplification transistor for amplifying a signal from the floating diffusion;
5. A MOS type image pickup device comprising: a readout transistor for switching between reading and non-reading of a signal amplified by the amplification transistor from the pixel. Solid-state imaging device. The pixel is a pixel including a photoelectric conversion unit that generates a photocurrent by photoelectric conversion with respect to incident light, and a peripheral circuit of the photoelectric conversion unit, and includes n one-dimensional pixel columns in which the pixels are arranged one-dimensionally. , A solid-state image pickup device that picks up an image by relatively moving a document image in the scan direction by using these one-dimensional pixel rows,
An image reading circuit common to each one-dimensional pixel column for horizontally reading image data obtained by imaging the original image from the n one-dimensional pixel columns;
The pixel column pitch that is the pitch of each one-dimensional pixel column in the scan direction in the n one-dimensional pixel columns is at least (n + 1) / n of the photoelectric conversion unit width that is the width of the photoelectric conversion unit in the scan direction. A solid-state imaging device characterized by being doubled.
However, the symbol “n” indicates a natural number of 2 or more, and the symbol “/” indicates division. A controller for controlling an image reading operation by the image reading circuit;
The controller is
The image reading is performed so that the image reading operation of all the n one-dimensional pixel columns is completed during a time in which one one-dimensional pixel column moves a distance corresponding to the resolution pitch in the scan direction in the document image. The solid-state imaging device according to claim 6, wherein the circuit is caused to execute an image reading operation.   The solid-state imaging device according to claim 6, wherein the pixel column pitch is not less than (n + 1) / n times and less than 4 times the width of the photoelectric conversion unit. The image readout circuit includes:
A circuit connected to the vertical signal lines for image readout that are wired in the scan direction over the n one-dimensional pixel columns, and for reading out the pixel signals of the respective pixels in each one-dimensional pixel column in time series. The solid-state imaging device according to claim 6, wherein the solid-state imaging device is provided. The pixels constituting the one-dimensional pixel row are
The photoelectric conversion unit;
A floating diffusion for accumulating the charge from the photoelectric conversion unit and converting the charge into a voltage;
A reset transistor for applying a reset bias to the floating diffusion;
A transfer transistor for switching between transfer and non-transfer of the photocurrent to the floating diffusion; and
An amplification transistor for amplifying a signal from the floating diffusion;
7. A MOS type imaging device comprising: the peripheral circuit having a readout transistor for switching between reading and non-reading of a signal amplified by the amplification transistor from the pixel. The solid-state imaging device according to any one of 9.

Images