JPH0888808A - Solid-state image pickup device and drive method therefor - Google Patents

Abstract

PURPOSE: To provide a solid-state image pickup device and a drive method therefor for reducing the number of vertical scanning circuit units to half the number of picture elements in a vertical direction and independently and successively scanning and reading all the picture elements. CONSTITUTION: This device is provided with a vertical scanning circuit 2 composed of the vertical scanning circuit units 2-1,... corresponding to every other picture element rows in the vertical direction and a selection row changeover switch part 3 composed of a first switch 3a and a second switch 3b for transmitting the output of the units 2-1,... to the picture element rows of the preceding stage and poststage of the rows corresponding to the units 2-1,.... Then, selection signals outputted from the units 2-1,... are outputted over consecutive two horizontal scanning periods, the first changeover switch is made conductive and the second switch is made nonconductive in the first horizontal scanning period and the second switch is made conductive and the first switch is made nonconductive in the following horizontal scanning period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device and a driving method thereof.

[0002]

2. Description of the Related Art Generally, in an XY address type solid-state image pickup device for reading out a signal of a pixel array in which pixels are arranged in a matrix in an XY address system, in order to realize all pixel independent sequential scanning, one pixel row is used. On the other hand, one vertical scanning circuit unit for controlling the image pickup state of pixels is required. This configuration is shown in FIG. In FIG. 6, 101 is a horizontal scanning circuit, 102 is a vertical scanning circuit, 102-1 is a vertical scanning circuit unit, and 103 is a pixel. The horizontal scanning circuit 101 sequentially outputs the signals of the pixels in the row selected by the vertical scanning circuit 102, and the vertical scanning circuit 102 puts the pixels in each row into a selected state or a non-selected state. In order to realize all-pixel independent sequential scanning, it is necessary to control each pixel row independently in the selected / non-selected state. Therefore, as shown in FIG. 6, the vertical scanning circuit unit 102-1 has the same number of pixels in the vertical direction. The same number is required.

[0003]

In the case of realizing all pixel independent sequential scanning with such a configuration, if the pixel pitch in the vertical direction is reduced, the pitch of the scanning circuit must be reduced. Requires processing technology. Further, when it is difficult to reduce the pitch of the scanning circuit to the pixel pitch, it can be realized by disposing the scanning circuits on both sides of the pixel region as disclosed in Japanese Patent Application No. 4-283506. , Causing an increase in area. Furthermore, if the number of pixels in the vertical direction increases, the number of units of the scanning circuit must increase accordingly. These have a problem that the manufacturing yield of the solid-state imaging device of all-pixel independent sequential scanning is reduced as compared with the solid-state imaging device of two-row mixed interlaced scanning, which can be realized by a vertical scanning circuit having half the number of vertical pixels. Further, as in a solid-state imaging device compatible with two-row mixed interlaced scanning, a method of realizing sequential scanning by a vertical scanning circuit having half the number of vertical pixels is disclosed in JP-A-6-9826.
Although disclosed in No. 4, there is a problem in this method that the output signal is a two-row mixed signal and the vertical resolution corresponding to the number of vertical pixels cannot be obtained.

The present invention has been made to solve the above problems in the conventional solid-state image pickup device of all-pixel independent sequential scanning system. The inventions described in claims 1, 2, 3 and 7 are vertical scanning circuits. It is an object of the present invention to provide a solid-state imaging device capable of realizing all-pixel independent sequential scanning readout with half the number of pixels in the vertical direction and a driving method thereof.

The invention according to claim 4 is the same as claims 1 to 3.
It is an object of the present invention to provide a solid-state imaging device capable of controlling the first and second switching means in each invention described in any one of 1) to 1 above with one input clock.

The invention according to claim 5 is the same as claims 1 to 4.
It is an object of the present invention to provide a solid-state imaging device capable of forming the first and second switching means in each invention described in any one of 1) to 1) on the same substrate as the solid-state imaging device.

Further, the invention according to claim 6 is defined by claims 1 to 5.
In each invention described in any one of (1) to (4) above, it is an object of the present invention to provide a solid-state imaging device capable of uniforming outputs from pixels in all rows.

The invention according to claim 8 is the same as claim 1.
In each of the inventions described in any one of (1) to (6), a solid-state imaging device is provided which can obtain a signal component that does not depend on incident light information included in all-pixel independent sequential scanning read-out signals without blocking the solid-state imaging device. It is an object of the present invention to provide a driving method of the.

[0009]

In order to solve the above problems, the invention according to claim 1 selects a read row of a pixel array arranged in a matrix according to the output of a vertical scanning circuit. In the solid-state imaging device described above, a vertical scanning circuit composed of a vertical scanning circuit unit corresponding to every other pixel row in the vertical direction, and the output of each vertical scanning circuit unit is arranged in front of the pixel row corresponding to the unit. Output from each of the vertical scanning circuit units, comprising first switching means for transmitting to each row, and second switching means for transmitting the output of each vertical scanning circuit unit to a pixel row subsequent to the pixel row to which the unit corresponds. The selected signal is output over two consecutive horizontal scanning periods, and the first switching means is turned on during the first horizontal scanning period.
The second switching means is rendered non-conductive during the subsequent horizontal scanning period, rendered non-conductive during the first horizontal scanning period, and rendered conductive during the subsequent horizontal scanning period.
Also, the switching operation of the second switching means is configured to be performed during the horizontal blanking period. According to a second aspect of the present invention, in the first aspect of the invention, each vertical scanning circuit unit is configured to correspond to an odd-numbered pixel row. The invention of claim 3 is the same as claim 1.
In the invention described above, each vertical scanning circuit unit is configured to correspond to an even-numbered pixel row.

In this way, the selection signal output from each vertical scanning circuit unit is output over two consecutive horizontal scanning periods, and the first switching means is conductive and the second switching means is non-conductive in the first horizontal scanning period. Then, in the subsequent horizontal scanning period, the second switching means is rendered conductive and the first switching means is rendered non-conductive, and the switching operation of the first and second switching means is performed in the horizontal blanking period. With this configuration, the vertical scanning circuit units, which are half the number of pixels in the vertical direction, can perform all pixel independent sequential scanning reading without mixing outputs according to incident light of two pixels in the vertical direction.

According to a fourth aspect of the present invention, in each of the first to third aspects of the present invention, the second switching means is controlled by an inverted clock of the clock for controlling the first switching means. It is composed of. Thereby, the first and second switching means can be controlled by one input clock.

According to a fifth aspect of the present invention, in each of the first to fourth aspects of the invention, the first and second switching means are constituted by switches formed of MOS transistors. . This makes it possible to form the first and second switching means on the same substrate as the solid-state imaging device.

According to a sixth aspect of the present invention, in each invention according to any one of the first to fifth aspects, between the pixel row to which each vertical scanning circuit unit corresponds and the output section of the unit, The configuration is equivalent to that of the first or second switching means, and is provided with a switching means that is always in a conductive state. This makes it possible to make the outputs from the pixels in all rows uniform.

According to a seventh aspect of the present invention, in the method for driving the solid-state image pickup device according to any one of the first to sixth aspects,
The signal of each pixel in the pixel row selected to be read by the vertical scanning circuit is read nondestructively, and the switching of the first and second switching means performed in the horizontal retrace period precedes the switching. This is performed after resetting the optical information accumulated in each pixel selected in the reading state in the horizontal reading period. As a result, the vertical scanning circuit composed of the vertical scanning circuit units, which is half the number of pixels in the vertical direction, does not mix outputs according to the incident light of two pixels in the vertical direction, and all pixel independent sequential scanning read operation is performed. Is possible.

The invention described in claim 8 is the method for driving a solid-state image pickup device according to any one of claims 1 to 6, wherein:
The signal of each pixel in the pixel row selected to be read by the vertical scanning circuit is read nondestructively, and the reading is performed after the switching of the first and second switching means performed in the horizontal blanking period. The light information accumulated in each pixel selected in the state is reset.
As a result, it is possible to obtain a dark equivalent output of the solid-state imaging device without blocking the solid-state imaging device.

[0016]

EXAMPLES Next, examples will be described. FIG. 1 is a circuit configuration diagram showing an embodiment of a solid-state imaging device according to the present invention. Although a solid-state image pickup device having a 4 × 5 pixel configuration is assumed in this embodiment, the present invention is not limited to this pixel configuration. In FIG. 1, 1 is a horizontal scanning circuit for sequentially outputting signals of pixels, 2 is a vertical scanning circuit, 2-
Reference numerals 1, 2-2, 2-3 are vertical scanning circuit units, 3 is a selection row changeover switch unit, 4 is a pixel capable of nondestructively reading out a signal corresponding to incident light, and arranged in a 4 × 5 matrix. It is arranged. Si (i = 1 to 4) is a signal extraction line, and Gi (i = 1 to 5) is a horizontal pixel selection line. Pixels in the same row in the horizontal direction are commonly connected to one horizontal selection line, and pixels in the same column in the vertical direction are commonly connected to one signal extraction line. And the vertical scanning circuit unit
When the pixel is selected, the pixel signal is read when the reset clock ΦR is “L”, and when the reset clock ΦR is “H”, a selection signal for resetting the charge accumulated in the pixel is output to the pixel. ing.

In addition, odd-numbered horizontal pixel selection lines G1, G3,
Vertical scanning circuit units 2-1 and 2-
The respective outputs L1, L2, L3 of 2, 2-3 are directly output,
Outputs L1 and L2 of the vertical scanning circuit unit 2-1 and 2-2 are output to the even-numbered horizontal pixel selection line G2 via the second and first switches 3b and 3a of the selected row changeover switch unit 3. Similarly, the vertical scanning circuit units 2-2 and 2-2 are connected to the horizontal pixel selection lines G4 of even rows.
-3 outputs L2 and L3 are selected row changeover switch section 3
Are output via the second and first switches 3b and 3a.

The selected row changeover switch unit 3 uses the selected row changeover clock ΦLi to output the vertical scanning circuit unit 2-.
The combination of rows transmitting the outputs L1, L2, L3 of 1, 2, 2 and 2-3 is changed, and when ΦLi is “H”, the output L1 of the vertical scanning circuit 2 is the horizontal pixel selection line G1, The output L2 is the horizontal pixel selection line G3, G
4, the output L3 is output to the horizontal pixel selection line G5, and when ΦLi is “L”, the output L1 is the horizontal pixel selection line G1, the output L2 is the horizontal pixel selection lines G2 and G3, and the output L3 is the horizontal pixel. It is output to the selection lines G4 and G5. The output Li (i = 1 to 3) of the vertical scanning circuit unit outputs a ternary pulse, and the lowest level of the ternary signals is in the non-selected state and the intermediate level is in the selected state. Is read out and the signal charge is reset in the selected state at the highest level. The highest level, that is, the timing of resetting the selected pixel corresponds to the time when the reset clock ΦR becomes “H”.

Next, the operation of the solid-state image pickup device configured as described above will be described with reference to the timing chart shown in FIG. From time t ₁ to time t ₄ , the horizontal pixel selection line G1 is in the selected state. Since ΦLi is “L” from t ₁ to t ₂ , the pixel rows other than the first row are not selected. After resetting the optical information of the pixels in the selected row according to "H" of the reset clock ΦR which becomes "H" in the horizontal blanking period (HBL) at t ₂ , ΦLi is set to "H". Since ΦLi is “H” from t ₃ to t ₄ , the pixels in the first row and the second row are selected. As for the pixels on the first row, since they have just been reset at t ₂ , little optical information is stored. Therefore, during the period of t ₃ , the dark output of the pixels in the first row (1d) and the dark output of the pixels in the second row (2
The total signal of d) and the output (2s) corresponding to the optical information is output as the output signal. At t ₄ , the optical information accumulated in the pixels of the first row and the second row is reset according to the reset clock ΦR.

Similarly, during the period of t ₅ , the dark output (2d) of the pixels of the second row and the dark output (3 of the pixels of the third row).
d) and an output (3s) corresponding to the light information, and during the period of t ₇ , the dark output (3d) of the pixels in the third row and the dark output (4d) of the pixels in the fourth row and the light information. Output according to (4s)
Is output, and during the period of t ₉ , the dark output (4d) of the pixels in the fourth row, the dark output (5d) of the pixels in the fifth row, and the output (5s) according to the optical information are obtained. Therefore, t ₃
The output according to each light information of the pixel of the second row, the pixel of the third row at t ₅ , the pixel of the fourth row at t ₇ , and the pixel of the fifth row at t ₉ is read independently for each row. Become.

As can be seen from the above description, the signal to be read is the total of the dark output for two pixels and the output corresponding to the optical information for one pixel. Since a signal required as a video signal is only a signal corresponding to optical information, the dark output for two pixels may be subtracted from the read signal in order to form the video signal. In this case, if the dark output of each pixel is constant, a constant value may be subtracted from the read signal. However, if the dark output is not constant because it varies from pixel to pixel, Even if a constant value is subtracted, leftovers occur and fixed pattern noise in the dark occurs in the video signal. The following method is generally used to remove the dark fixed pattern noise. That is, first, the dark output is read from the imaging device, and this signal is stored in the memory. Next, the dark output of the corresponding pixel stored in the memory is subtracted from the signal read from the image pickup device. The fixed pattern noise in the dark can be removed by the above operation.

In order to obtain a dark output from the image pickup device, a signal may be read out by using a mechanical or optical shutter so that light does not enter the image pickup device. However, it is not preferable to use a mechanical or optical shutter because the number of components is increased, which causes an increase in cost and a decrease in reliability. Therefore, a method for obtaining a dark output from the image pickup device without shielding the image pickup device will be described next.

In the solid-state image pickup device of the above embodiment, the signal corresponding to the optical information of the pixel in the selected state is read out, the optical information is reset, and then the selected row changeover switch unit is switched to change the combination of the selected rows. The next signal is read out to obtain an output according to the optical information of each row. However, by continuing the timing of switching the selected row changeover switch unit before resetting the optical information, the following operation continues. During the signal reading period, the dark output having no light information of the pixels in the selected row can be read without blocking the solid-state imaging device.

A method of reading the dark output will be described with reference to the timing chart shown in FIG. In reading the dark output, for example, at time t ₄₀ , ΦLi =
Since “L” and ΦR = “H”, horizontal pixel selection lines G2 and G
The reset level is output to 3 and the horizontal pixel selection line G2
The signal charges of the pixels in the row corresponding to G3 are reset.
At time t ₅₀ , since ΦLi = “L” and ΦR = “L”, the signal read level is output to the horizontal pixel selection lines G2 and G3, and the signal immediately after reset of the pixels in the row corresponding to the horizontal pixel selection lines G2 and G3. Is read. In this case, the horizontal pixel selection lines G2 and G3 that are in the selected state immediately after the reset operation are performed.
In the pixel of the row corresponding to, the optical information is stored for the time from the end of the reset operation to the start of the read operation, but since it is sufficiently smaller than the normal optical information storage time, that is, one vertical scanning period, this storage effect Can be almost ignored. Therefore, the signal read here can be treated as a dark signal.

The above description has been made on the assumption that the signal from the pixel is composed of a dark output and an output according to optical information. For example, it is assumed that the charges generated by the incident light are read directly. In the case of the solid-state imaging device having such a configuration, the output in the dark is zero. In such a case, the signal from the pixel in the selected state is only the output corresponding to the light information from one pixel, and it is not necessary to subtract the dark output when forming the video signal. That is, in FIG. 2, for example, at time t ₅ , the output is only (3 s).

In the above embodiment, the output from the vertical scanning circuit unit has three values and one horizontal pixel selection line is provided for each unit. However, the selection signal line and the reset signal line are independent and It is also possible to use two horizontal pixel selection lines per row.

Further, in the above embodiment, the operation for resetting the optical information accumulated in the selected pixel in response to the "H" of the reset clock .PHI.R during the horizontal blanking period has been described. However, in the case of reading the signal itself resets the accumulated optical information, that is, in the case of destructive reading, this reset operation is unnecessary, and the output from the vertical scanning circuit unit is a binary pulse of non-selection / selection. Good.

FIG. 4 shows a specific configuration example of the selected row changeover switch section 3. In FIG. 4, the selection signal output from the vertical scanning circuit unit is the horizontal pixel selection lines Gi and P.
The source of the channel MOS transistor Q1, the drain of the N-channel MOS transistor Q2, and the P-channel M
It is connected to the source of the OS transistor Q3 and the drain of the N-channel MOS transistor Q4,
Transistor Q1 and N-channel MOS transistor Q2
Form a first switch 3a, and a P-channel MOS transistor Q3 and an N-channel MOS transistor Q4 form a second switch 3b. ΦLi is input to the gates of the P-channel MOS transistor Q1 and the N-channel MOS transistor Q4, and the inverted signal / ΦLi of ΦLi is input to the gates of the N-channel MOS transistor Q2 and the P-channel MOS transistor Q3. Therefore, when ΦLi is “H”, the P-channel MOS transistor Q3 and the N-channel MOS transistor Q4 are rendered conductive, and the selection signal output from the vertical scanning circuit unit is supplied to the horizontal pixel selection lines Gi and Gi + 1. When .PHI.Li is "L", the P-channel MOS transistor Q1 and the N-channel MOS transistor Q2 are rendered conductive, and the selection signal output from the vertical scanning circuit unit is supplied to the horizontal pixel selection lines Gi-1 and Gi.

Here, the selected row changeover switch section is similar to the field changeover switch in the solid-state image pickup device for two-row mixed interlaced scanning, but during interlaced scanning, this switch is switched during the vertical blanking period. , Switching can take a relatively long time. In the present invention, since the selected row changeover switch section is changed over within the horizontal blanking period, it is necessary to have a higher changeover speed than the field changeover switch in the solid-state imaging device compatible with two-row mixed interlaced scanning. To this end, when a switch is formed by MOS transistors, the power supply voltage is increased, the gate width of the MOS transistors is increased, the gate length is decreased, and the ability of the clock output buffer to control the switches is increased. There are ways to increase it.

In the present invention, since the output of the pixels in each row is independently taken out, it is desirable that the selection signal output from the vertical scanning circuit unit be similarly output to the pixels in each row. However, in the configuration of the embodiment shown in FIG.
Output from the vertical scanning circuit unit (selection signal) Li (i
= 1 to 3) is directly output to the pixels in the odd-numbered rows without passing through the switches in the selected-row changeover switch unit, and is output to the pixels in the even-numbered rows via the switches in the selected-row changeover switch unit. To be done. This configuration can cause non-uniform output in the pixels in the odd rows and the pixels in the even rows. Therefore, as in the embodiment shown in FIG. 5, the switches 3a, which constitute the selected row changeover switch unit 3, are provided between the horizontal pixel selection lines G1, G3, G5 corresponding to the pixels in the odd rows and the vertical scanning circuit unit. This problem is solved by providing the dummy switch 5 which is always in the conductive state with the same configuration as 3b.

In each of the above-described embodiments, the vertical scanning circuit unit is described as being associated with the pixels in the odd-numbered rows, but the vertical scanning circuit unit is associated with the even-numbered rows and the selected rows are switched to the odd rows before and after. The same effect can be obtained even if the connection is made via the first and second switches of the switch section. Further, in the present invention, since it suffices to pay attention to the selection state of pixels in the horizontal direction, the configuration of the horizontal scanning circuit is not limited as long as the signals of the pixels in the selected horizontal direction are sequentially output.

[0032]

As described above on the basis of the embodiments,
According to each of the first to third aspects of the present invention, the vertical scanning circuit composed of the vertical scanning circuit units, which is half the number of pixels in the vertical direction, mixes the outputs according to the incident light of two pixels in the vertical direction. A solid-state imaging device capable of performing independent sequential scanning reading of all pixels can be obtained. According to the invention described in claim 4, since the first and second switching means in each invention described in any one of claims 1 to 3 are configured to be controlled by one input clock, the input terminal It is possible to obtain a solid-state imaging device in which the number is reduced and the driving is easy. According to the invention of claim 5, claims 1 to 4
Since the first and second switching means in each invention described in any one of 1 to 3 are composed of switches composed of MOS transistors, the first and second switching means should be formed on the same substrate as the solid-state imaging device. Therefore, it is possible to reduce the scale of the entire configuration. According to a sixth aspect of the invention, in each of the first to fifth aspects of the invention, a pixel in a row to which the vertical scanning circuit unit corresponds and a pixel in a row to which the vertical scanning circuit unit does not correspond. Therefore, it is possible to extract a uniform signal.

According to the seventh aspect of the invention, the vertical scanning circuit composed of the vertical scanning circuit units, which is half the number of pixels in the vertical direction, mixes the outputs according to the incident light of the two pixels in the vertical direction. Without doing so, it is possible to obtain a method for driving a solid-state imaging device that performs independent pixel sequential scanning reading. According to the invention described in claim 8, a dark-time output that does not depend on incident light information contained in all pixel independent sequential scanning read signals obtained in the solid-state imaging device according to any one of claims 1 to 6 is provided. It is possible to obtain the solid-state imaging device without blocking the light.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a solid-state imaging device according to the present invention.

FIG. 2 is a timing chart for explaining a driving method of the embodiment shown in FIG.

FIG. 3 is a timing chart for explaining a driving method for obtaining a dark output in the embodiment shown in FIG.

FIG. 4 is a diagram showing a configuration example of a selected row changeover switch unit in the embodiment shown in FIG.

FIG. 5 is a circuit configuration diagram showing another embodiment.

FIG. 6 is a circuit configuration diagram showing a configuration example of a conventional solid-state imaging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Horizontal scanning circuit 2 Vertical scanning circuit 2-1, 2-2, 2-3 Vertical scanning circuit unit 3 Selected row changeover switch part 3a 1st switch 3b 2nd switch 4 Pixel 5 Dummy switch

Claims (8)

[Claims] 1. A solid-state imaging device in which a readout row of a pixel array arranged in a matrix is selected by the output of the vertical scanning circuit, and the vertical scanning circuit corresponds to every other pixel row in the vertical direction. A vertical scanning circuit composed of a unit, first switching means for transmitting the output of each vertical scanning circuit unit to a pixel row preceding the pixel row corresponding to the unit, and the unit for outputting the output of each vertical scanning circuit unit. A second switching means for transmitting to a subsequent pixel row of the corresponding pixel row, the selection signal output from each of the vertical scanning circuit units is output over two consecutive horizontal scanning periods. The first switching means is conductive during the first horizontal scanning period, is non-conductive during the subsequent horizontal scanning period, and the second switching means is non-conductive during the first horizontal scanning period. The solid-state image pickup device is configured to be conductive during a subsequent horizontal scanning period and to perform switching operations of the first and second switching means during a horizontal blanking period. 2. The solid-state imaging device according to claim 1, wherein each vertical scanning circuit unit is configured to correspond to an odd-numbered pixel row. 3. The solid-state imaging device according to claim 1, wherein each vertical scanning circuit unit is configured to correspond to an even-numbered pixel row. 4. The second switching means is configured to be controlled by an inverted clock of a clock controlling the first switching means.
4. The solid-state imaging device according to any one of 3 to 3. 5. The first and second switching means are M
The solid-state imaging device according to any one of claims 1 to 4, wherein the solid-state imaging device includes a switch including an OS transistor. 6. Switching between a pixel row to which each of the vertical scanning circuit units corresponds and an output section of the unit, which has a configuration equivalent to that of the first or second switching means and is always in a conductive state. The solid-state imaging device according to any one of claims 1 to 5, further comprising means. 7. The method for driving a solid-state imaging device according to claim 1, wherein the signals of the respective pixels in the pixel row selected to be read by the vertical scanning circuit are read nondestructively. In addition, the switching of the first and second switching means during the horizontal blanking period is performed after resetting the optical information accumulated in each pixel selected to be in the readout state in the horizontal readout period prior to the switching. A method for driving a solid-state imaging device, comprising: 8. The method for driving a solid-state image pickup device according to claim 1, wherein signals of respective pixels of a pixel row selected to be read by the vertical scanning circuit are read nondestructively. And the optical information stored in each pixel selected in the read state is reset after the first and second switching means are switched during the horizontal retrace line period. Driving method.