JP2005101752A - Solid-state imaging device and drive method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging device increased in sensitivity and miniaturized, and a drive method therefor. <P>SOLUTION: The solid-state imaging device includes: a first sensor array 2; a second sensor array 3 requiring same spectral sensitivity as that of the first sensor array 2; a vertical register 4 for vertically transferring signal electric charge stored in the second sensor array; a read gate 5 for reading signal electric charge stored in the first sensor array and the signal electric charge transferred by the vertical register; and a horizontal register 7 for horizontally transferring the signal electric charge read by the read gate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solid-state imaging device and a driving method thereof. Specifically, the present invention relates to a solid-state imaging device having two or more sensor rows that require the same spectral sensitivity and a driving method thereof.

  A horizontal register in which pixels consisting of photodiodes that store signal charges in an amount corresponding to incident light are arranged one-dimensionally, and signal charges from these pixels are transferred to the output unit by a charge transfer method of a CCD (Charge Coupled Device) The CCD linear sensor having is used in many fields such as copying, facsimile, OCR, pattern recognition and various measurements.

  Here, in order to improve the reading resolution in the main scanning direction of the CCD linear sensor, that is, the reading resolution in the arrangement direction of the imaging elements in the CCD linear sensor chip, the number of imaging elements constituting the CCD linear sensor chip is set to Need to increase. However, if the size of each element is the same and the number is increased, the CCD linear sensor chip becomes larger and its price increases.

  In addition, when each element is downsized and the number of image pickup elements is increased without increasing the size of the CCD linear sensor chip, the sensitivity of the CCD linear sensor chip is proportional to the light receiving area per unit pixel. There is a disadvantage in that the amount of received light decreases, the sensitivity of the chip of the CCD linear sensor decreases, and the reading speed and S / N ratio decrease.

  Conventionally, as a color image pickup device that can read a high-quality image with a simple configuration without increasing the cost, the image pickup device array in which a plurality of image pickup devices are linearly arranged. Are arranged in parallel with each other on a substrate, corresponding to each of a plurality of colors, and each imaging element column is arranged in the direction of arrangement of the imaging elements with respect to the other imaging element rows in the imaging element group. There has been proposed a color image sensor arranged so that the positions of the individual image sensors coincide with each other (for example, see Patent Document 1).

JP 2001-309121 A (page 2-6, FIG. 1)

  However, the conventional color image sensor described above has a problem in that it is difficult to reduce the size of the solid-state image sensor because the horizontal charge transfer unit corresponding to each sensor array is formed. It was.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a solid-state imaging device and a driving method thereof that can realize downsizing without reducing sensitivity.

  In order to achieve the above object, a solid-state imaging device according to the present invention includes a first sensor row and a first sensor row in a solid-state imaging device having two or more sensor rows that require the same spectral sensitivity. A second sensor array provided adjacent thereto, a vertical charge transfer section for transferring at least a signal charge stored in the second sensor array in a vertical direction, and a signal charge stored in the first sensor array; And a read gate for reading the signal charge transferred by the vertical charge transfer unit, and a horizontal charge transfer unit for transferring the signal charge read by the read gate in the horizontal direction.

Here, the first sensor array and the second sensor array provided adjacent to the first sensor array can accumulate signal charges in an amount corresponding to the incident light by photoelectrically converting the incident light. it can.
Further, the signal charge transferred to the vertical charge transfer unit may be transferred to a position where it can be read out by the read gate by the vertical charge transfer unit that transfers at least the signal charge accumulated in the second sensor array in the vertical direction. it can.
Further, the signal charges accumulated in the first sensor column and the signal charges transferred by the vertical charge transfer unit are read out and read out by the signal charge and vertical charge transfer unit accumulated in the first sensor column. Signal charges can be added.
Further, the signal charge added by the read gate can be transferred to the output unit by the horizontal charge transfer unit that transfers the signal charge read by the read gate in the horizontal direction.

  In order to achieve the above object, a method for driving a solid-state imaging device according to the present invention includes a first sensor row, and the first sensor row provided adjacent to the first sensor row. A second sensor array that requires the same spectral sensitivity, a vertical charge transfer unit that transfers at least a signal charge stored in the second sensor array in a vertical direction, and a signal charge stored in the first sensor array And a driving method of the solid-state imaging device, comprising: a readout gate that reads out the signal charge transferred by the vertical charge transfer unit; and a horizontal charge transfer unit that transfers the signal charge read out by the readout gate in a horizontal direction, The step of imaging a predetermined line with the second sensor array, and the step of transferring the signal charge accumulated in the second sensor array to the vertical charge transfer unit by imaging with the second sensor array. And imaging the same line as the line imaged with the second sensor array with the first sensor array, and imaging the first sensor array with the first sensor array. Reading out the signal charges accumulated in the image sensor and the signal charges accumulated by performing imaging with the second sensor array transferred to the vertical charge transfer unit by a readout gate, and accumulating at least in the second sensor array Transferring the signal charge obtained by adding the signal charge and the signal charge accumulated in the first sensor array from the read gate to the horizontal charge transfer unit.

Here, by imaging a predetermined line with the second sensor array, signal charges based on imaging of the predetermined line can be accumulated in the second sensor array.
Further, the signal charges accumulated in the second sensor array are transferred to the vertical charge transfer unit by performing imaging with the second sensor array, and the signal charges accumulated in the second sensor array are read out by the read gate. Transfer to a position where reading is possible is possible.
Furthermore, by imaging the same line as the line imaged with the second sensor array with the first sensor array, the same line as the line imaged with the second sensor array is captured in the first sensor array. It is possible to accumulate signal charges based on imaging.
In addition, the signal charges accumulated in the first sensor array by imaging with the first sensor array and the signal charges accumulated by imaging with the second sensor array transferred to the vertical charge transfer unit are obtained. By reading out by the readout gate, the signal charge accumulated in the first sensor array and the signal charge accumulated in the second sensor array can be added.
Further, at least a predetermined line is imaged by the second sensor array, and the signal charge accumulated in the second sensor array and the same line as the line imaged by the second sensor array are captured by the first sensor array. A signal charge obtained by adding the signal charges accumulated in the first sensor array by performing imaging is transferred from the read gate to the horizontal charge transfer unit, whereby the first sensor array performs imaging by at least the first sensor array. The signal charges accumulated in the sensor array and the signal charges accumulated by performing imaging with the second sensor array can be added and output to the output unit.

  In the solid-state imaging device to which the present invention is applied and the driving method thereof, downsizing can be realized without reducing the sensitivity.

  FIG. 1 is a schematic plan view for explaining a CCD linear sensor which is an example of a solid-state imaging device to which the present invention is applied. The CCD linear sensor 1 shown here is a first sensor array 2 composed of 10000 pixels indicated by s1 to s10000, and is provided adjacent to the first sensor array consisting of 10000 pixels indicated by t1 to t10000. Second sensor array 3, vertical register 4 for transferring signal charges stored in pixels of second sensor array in the vertical direction, storage in pixels of first sensor array provided adjacent to first sensor array The readout gate 5 for reading out the signal charge transferred by the vertical register and the horizontal register 7 for transferring the signal charge read out by the readout gate to the FD unit 6 are provided.

The horizontal register is a two-phase drive, and horizontal drive pulses φ1 and φ2 are applied, and φ1 and φ2 are two levels of high level (hereinafter referred to as H level) and low level (hereinafter referred to as L level), respectively. The signal charge is transferred by these.
A vertical drive pulse V1 is applied to the first electrode (hereinafter referred to as Vφ1) 8 of the vertical register, and a vertical drive pulse V2 is applied to the second electrode (hereinafter referred to as Vφ2) 9 of the vertical register. V1 and V2 take binary values of H level and L level, respectively, and signal charges are read and transferred by these values.
Further, a read pulse φROG is applied to the read gate, and φROG takes a binary value of H level and L level. When the read pulse is at the H level, the signal charge is read to the read gate.

  Hereinafter, a method for driving the CCD linear sensor configured as described above will be described. That is, an example of a driving method of the solid-state imaging device to which the present invention is applied is the unit storage time of the CCD solid-state imaging device, that is, the time from the application of the first readout pulse to the application of the subsequent readout pulse. An example of a driving method of a CCD linear sensor that moves in the sub-scanning direction by a distance d equal to the width of the sensor row and the second sensor row and scans the imaging region indicated by reference symbol a in FIG. An example of a method for driving a solid-state imaging device will be described with reference to a diagram illustrating a transfer state of signal charges accumulated in pixels indicated by reference numerals s3, s4, t3, and t4 in FIG. Note that reference numerals (1) to (3) in FIG. 2 represent areas obtained by dividing the imaging area for each distance d, and reference numeral b in FIG. 2 indicates an area that can be scanned by the first sensor array, and reference numeral c. Indicates an area that can be scanned by the second sensor array.

In an example of a method for driving a CCD linear sensor to which the present invention is applied, at time t1, as shown in FIG. 3, φROG and V1 are at an L level and V2 is at an H level. In this state, FIG. As shown in FIG. 4 (t), by scanning the area indicated by reference numeral (1) in FIG. 2 in the first sensor array and the area indicated by reference numeral (2) in FIG. 2 in the second sensor array, FIG. as shown in _1), together with the signal charges represented by Q ₁₁ to the first sensor array is accumulated signal charges represented by Q ₁₂ is accumulated in the second sensor array. Also, Q ₀₁ is stored for at time t1 time t0 is earlier time accumulated by the second sensor array to V.phi.2.

Here, Q _xy indicates the signal charge accumulated by scanning the area indicated by (y) at time x. Since photoelectric conversion is always performed in the sensor array in accordance with incident light, actually, Q _xy reads the signal charge from the sensor array after the first pulse for reading the signal charge from the sensor array is applied. For the convenience of explanation, in this specification, for the convenience of explanation, the first pulse is applied and the second pulse is applied. The description is made assuming that the accumulated signal charges are accumulated at a certain time.

Then, at time t2, by the φROG to H level, as shown in FIG. 4 (t _2), Q ₁₁ accumulated in the first sensor array is read out to the readout gate.

Then, at time t3, by the V2 at the L level, as shown in FIG. 4 _{(t 3), Q 01} accumulated in the Vφ2 is read to the read gate, read at time t2 and Q ₁₁ and _{Q 01} are added by the read-out gate.

Next, at time t4, by the V1 and H level, as shown in FIG. _{4 (t} 4), _{Q 12} accumulated in the first sensor array is transferred to V.phi.1.

Then, at time t5, by the φROG the L level, as shown in FIG. 4 _{(t 5),} and the _{Q 11} and _{Q 01} are transferred to the horizontal register.
The signal charge transferred to the horizontal register is subjected to normal CCD register transfer in which φ1 and φ2 are alternately set to H level and L level, and the region indicated by reference numeral (1) in FIG. 2 is scanned at time t0 and time t1. The signal charges accumulated at this time are added, transferred to the FD unit by the horizontal register, and output.

Then, at time t6, by the V2 and H level, as shown in FIG. 4 _{(t 6), Q 12} stored in Vφ1 it is transferred to V.phi.2.

Thereafter, the CCD linear sensor is moved in the sub-scanning direction by a distance d and V1 is set to L level, whereby φROG and V1 are set to L level and V2 is set to H level. In this state, FIG. As shown, the first sensor array scans the area indicated by reference numeral (2) in FIG. 2, and the second sensor array scans the area indicated by reference numeral (3) in FIG. _The signal charge represented by ₆₂ is accumulated, and the signal charge represented by Q ₆₃ is accumulated in the second sensor array. Also, Q ₁₂ is stored for at time t1 accumulated in the second sensor array to V.phi.2.
That is, the state in which V1 is set to the L level after time t6 is a relationship in which the position of the CCD linear sensor is different from the state at time t1, and the first sensor is obtained by repeatedly performing the operation from time t1 to t6. The same line is scanned by the column and the second sensor column, and the accumulated signal charges can be added by scanning each sensor column.

  FIG. 5 is a schematic plan view for explaining a CCD linear sensor which is another example of the solid-state imaging device to which the present invention is applied. The CCD linear sensor 1 shown here is a first sensor array 2 composed of 10000 pixels indicated by s1 to s10000, and is provided adjacent to the first sensor array consisting of 10000 pixels indicated by t1 to t10000. Signal charges accumulated in pixels of the third sensor column 10 and the second sensor column, which are composed of 10000 pixels indicated by the second sensor column 3 and u1 to u10000 and are adjacent to the second sensor column, and The vertical register 4 for transferring the signal charges accumulated in the third sensor row in the vertical direction, the signal charges accumulated in the pixels of the first sensor row provided adjacent to the first sensor row, and the vertical registers are transferred. And a horizontal register 7 for transferring the signal charge read by the read gate to the FD unit 6.

  Here, the vertical drive pulse V1 is applied to the first electrode (hereinafter referred to as Vφ1) 8 of the vertical register, and the vertical drive pulse V2 is applied to the second electrode (hereinafter referred to as Vφ2) 9 of the vertical register. A vertical drive pulse V3 is applied to the third electrode (hereinafter referred to as Vφ3) 11 of the register, and a vertical drive pulse V1 is applied to the fourth electrode (hereinafter referred to as Vφ4) 12 of the vertical register. The vertical drive pulse V2 is applied to the electrode 13 (hereinafter referred to as Vφ5), the vertical drive pulse V3 is applied to the sixth electrode (hereinafter referred to as Vφ6) 14 of the vertical register, and the seventh electrode (hereinafter referred to as Vφ6). , Vφ7) 15 is applied with a vertical drive pulse V4, V2, V3 and V4 take H level and L level, respectively, V1 is H level, middle level (hereinafter referred to as M level) and L level 3 Taken up, by reading and transfer of the signal charges takes place.

  Hereinafter, a method for driving the CCD linear sensor configured as described above will be described. That is, another example of the driving method of the solid-state imaging device to which the present invention is applied is a distance equal to the width of the first sensor row, the second sensor row, and the third sensor row in the unit accumulation time of the CCD solid-state imaging device. As an example, a driving method of the CCD linear sensor that moves in the sub-scanning direction by d and scans the imaging region indicated by symbol a in FIG. 6, s3, s4, t3, t4, u3 in FIG. Another example of the method for driving the solid-state imaging device will be described with reference to the diagram showing the transfer state of the signal charge accumulated in the pixel indicated by u4. Note that reference numerals (1) to (4) in FIG. 6 represent areas obtained by dividing the imaging area for each distance d, and reference numeral b in FIG. 6 indicates an area that can be scanned by the first sensor array. The middle symbol c indicates a region that can be scanned by the second sensor array, and the symbol e in FIG. 6 indicates a region that can be scanned by the third sensor array.

In another example of the driving method of the CCD linear sensor to which the present invention is applied, at time t2, as shown in FIG. 7, φROG, V1 and V3 are in the L level, and V2 and V4 are in the H level. 6A, in the first sensor row, the region indicated by reference numeral (1) in FIG. 6, in the second sensor row, the region indicated by reference numeral (2) in FIG. 6, the third sensor by performing scanning in the region indicated by the reference numeral in FIG. 6 column (3), as shown in FIG. 8 (t _2), the signal charges represented by Q ₂₁ are accumulated in the first sensor array, a second sensor together with the signal charges represented by Q ₂₂ is accumulated in the column, the signal charges are accumulated representing Q ₂₃ to the third sensor array. Further, V.phi.2 Q ₁₂ accumulated in the third sensor array at time t2 the time t1 is earlier time is stored in, Q ₁₁ accumulated in the second sensor array at time t1 is stored in Vφ5, Vφ7 Q ₀₁ stored in the third sensor array at time t 0, which is a time before time t _1, is stored.

Then, at time t3, by the V4 to L level while the φROG to H level, as shown in FIG. 8 _{(t 3),} stored in _{Q 21} and Vφ7 accumulated in the first sensor array The read Q ₀₁ is read to the read gate, and Q ₂₁ and Q ₀₁ are added at the read gate.

Next, at time t4, by the H level V3 with the V2 to L level, as shown in FIG. 8 _{(t 4), Q 12} accumulated in the Vφ2 is transferred to V.phi.3, the Vφ5 The stored Q ₁₁ is transferred to Vφ6.

Then, at time t5, M level V1, by the H level V4 while the V3 to the L level, as shown in FIG. 8 _{(t 5), Q 12} accumulated in the Vφ3 within Vφ4 is transferred, _{Q 11} accumulated in the Vφ6 is transferred to Vfai7.

Then, at time t6, the V1 L level, by the L level V4 while the V2 to H level, as shown in FIG. 8 _{(t 6), Q 12} accumulated in the Vφ4 within Vφ5 while being transferred, _{Q 11} accumulated in the Vφ7 is read to the read gate, and _{Q 21} and _{Q 01} and _{Q 11} read at time t3 is added at the readout gate.

Next, at time t7, by setting V1 to H level, V2 to L level, and V3 to H level, as shown in FIG. 8 (t ₇ ), Q accumulated in the third sensor array ₂₃ is transferred to V.phi.1, with _{Q 22} that has been stored in the second sensor row is transferred to V.phi.4, _{Q 12} accumulated in the Vφ5 is transferred to V.phi.6.

Then, at time t8, .phi.ROG and V3 the L level, by the H level V4 while the V1 to M level, as shown in FIG. _{8 (t} 8), _{Q 12} accumulated in the Vφ6 is Vφ7 Q ₂₁ , Q ₀₁ and Q ₁₁ stored in the read gate are transferred to the horizontal transfer register.
The signal charge transferred to the horizontal register performs normal CCD register transfer in which φ1 and φ2 are alternately set to H level and L level, and the area indicated by reference numeral (1) in FIG. 6 at time t0, time t1, and time t2. The signal charges accumulated at the time of scanning are added, transferred to the FD section by the horizontal register, and output.

Then, L level V1 while moving the CCD linear sensor distance d in the sub-scanning direction, by the V2 to H level, the _{Q 23} accumulated in the Vφ1 is transferred to V.phi.2, .phi.ROG, V1 and In this state, V3 is at the L level, and V2 and V4 are at the H level. In this state, as shown in FIG. 6 (b), the region indicated by the reference numeral (2) in FIG. area indicated by reference numeral in FIG. 6 column (3), a third signal charge represented by the sensor column Q ₈₂ to the first sensor column by performing scanning in the region indicated by the reference numeral (4) in FIG. 6 is accumulated The signal charge represented by Q ₈₃ is accumulated in the second sensor array, and the signal charge represented by Q ₈₄ is accumulated in the third sensor array. Further, V.phi.1 _{Q 23} accumulated in the third sensor array at time t2 is stored in, Vφ5 _{Q 22} accumulated in the second sensor array at time t2 is stored in the third at time t1 in Vφ7 Q ₁₂ is stored accumulated in the sensor array.
That is, the state in which V1 is set to the L level and V2 is set to the H level after time t8 is the only difference between the state at time t2 and the position of the CCD linear sensor, and by repeating the operation from time t2 to t8. It is possible to scan the same line with the first sensor row, the second sensor row, and the third sensor row, and add the signal charges obtained by scanning with each sensor row.

  In the above-described CCD linear sensor driving method to which the present invention is applied, the same line is scanned twice or three times with different sensor arrays, and the signal charge obtained by each scan is added to obtain an output signal. The CCD linear sensor can be miniaturized without reducing the sensitivity and by adopting a structure in which all the signal charges accumulated in the sensor array by a plurality of scans are transferred by the same horizontal register. Can do.

It is a typical top view for demonstrating the CCD linear sensor which is an example of the solid-state image sensor to which this invention is applied. It is a schematic diagram for demonstrating an example of the drive method of the solid-state image sensor to which this invention is applied. It is a timing chart of a clock about an example of a drive method of a solid-state image sensing device to which the present invention is applied. It is the figure which showed the transfer state of the signal charge taken in by the pixel shown by code | symbol s3, s4, t3, and t4 in FIG. 1 about an example of the drive method of the solid-state image sensor to which this invention is applied. It is a typical top view for demonstrating the CCD linear sensor which is another example of the solid-state image sensor to which this invention is applied. It is a schematic diagram for demonstrating another example of the drive method of the solid-state image sensor to which this invention is applied. It is a timing chart of the clock about other examples of the drive method of the solid-state image sensing device to which the present invention is applied. FIG. 7 is a diagram illustrating a transfer state of signal charges taken in by pixels denoted by reference numerals s3, s4, t3, t4, u3, and u4 in FIG. 6 for another example of a method for driving a solid-state imaging device to which the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 CCD linear sensor 2 1st sensor row | line | column 3 2nd sensor row | line | column 4 Vertical register 5 Reading gate 6 FD part 7 Horizontal register 8 1st electrode 9 2nd electrode 10 3rd sensor row | line | column 11 3rd electrode 12 Fourth electrode 13 Fifth electrode 14 Sixth electrode 15 Seventh electrode

Claims (2)

In a solid-state imaging device having two or more sensor rows that require the same spectral sensitivity,
A first sensor row;
A second sensor row provided adjacent to the first sensor row;
A vertical charge transfer unit that transfers at least the signal charge accumulated in the second sensor array in the vertical direction;
A readout gate for reading out the signal charges accumulated in the first sensor array and the signal charges transferred by the vertical charge transfer unit;
A solid-state imaging device, comprising: a horizontal charge transfer unit that transfers a signal charge read by the read gate in a horizontal direction. The first sensor array, the second sensor array that is adjacent to the first sensor array and requires the same spectral sensitivity as the first sensor array, and at least the second sensor array are accumulated. A vertical charge transfer unit that transfers the signal charge in the vertical direction, a read gate that reads the signal charge accumulated in the first sensor array and the signal charge transferred by the vertical charge transfer unit, and a read gate that reads the signal charge. A method for driving a solid-state imaging device including a horizontal charge transfer unit that transfers a signal charge that has been output in a horizontal direction,
Imaging a predetermined line with the second sensor array;
Transferring signal charges accumulated in the second sensor array to the vertical charge transfer section by performing imaging with the second sensor array;
Imaging the same line as the line imaged with the second sensor array with the first sensor array;
The signal charge accumulated in the first sensor array by imaging with the first sensor array and the signal charge accumulated by imaging with the second sensor array transferred to the vertical charge transfer unit Reading through the readout gate;
Transferring at least the signal charge accumulated in the second sensor array and the signal charge accumulated in the first sensor array from the read gate to the horizontal charge transfer section. A method for driving a solid-state imaging device.

Images