JP2008067241A - Solid-state image pickup device and image pickup system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image pickup device that simultaneously reads a system control signal such as a focus control signal and an image-pickup signal, and also to provide an image pickup system using the same. <P>SOLUTION: The solid-state image pickup device is provided with: a pixel part 11 in which a plurality of pixels respectively including a photoelectric conversion element are two-dimensionally arrayed; a vertical signal line 10 for a focus control signal, which is used for outputting a signal from each pixel 6 for a focus control signal respectively set at a specific position in the pixel part; a vertical scanning circuit 9; a transfer switch 13; a horizontal scanning circuit 8; a part 7 for reading out a focus control signal; a vertical signal line 5 for an image pickup signal, which is used for outputting a signal from each image-pickup pixel 1 other than each pixel for a focus control signal; a vertical scanning circuit 4; a transfer switch 12; a horizontal scanning circuit 3; and a part 2 for reading an image-pickup signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device capable of simultaneously reading an imaging signal and a system control signal, and an imaging system using the same.

Conventionally, for example, as disclosed in JP-A-6-141225, pixels having two-dimensionally arranged photoelectric conversion elements, a V-direction address register for arbitrarily designating a pixel row to be read, and a pixel A solid-state imaging device having a vertical signal line commonly connected to a pixel column for reading a signal and an H direction address register for arbitrarily selecting a pixel signal to be read from a pixel row selected by a V direction address register By controlling the V-direction address register and the H-direction address register, it is possible to read out pixel signals from pixels at arbitrary positions in the pixel portion, and by limiting the pixels to be read out, focus control using the pixel signals can be performed at high speed. What is comprised so that it can be performed by is known.
JP-A-6-141225

  In the prior art disclosed in the above publication, it is possible to speed up the focus control by using a part of the pixel signal as the focus control signal, but the focus control signal readout and the imaging signal readout can be performed simultaneously. There was no limit to speeding up the focus control. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to provide a solid-state imaging device capable of simultaneously reading a focus control signal and an imaging signal, and an imaging system using the same. To do.

  In order to solve the above problem, the invention according to claim 1 is characterized in that a common well made of a first conductive type semiconductor and a second conductive different from the first conductive semiconductor formed in the common well. A plurality of pixels including photoelectric conversion elements made of a type semiconductor, a pixel unit in which the pixels are arranged two-dimensionally, and a signal from a system control pixel set at a plurality of specific positions in the pixel unit is output. 1 vertical signal line, a first vertical scanning circuit for selecting a row related to the system control pixel that outputs a signal to the first vertical signal line, and a signal related to the system control pixel to the outside The first signal readout unit, the first transfer switch connecting the first vertical signal line and the first signal readout unit, and the first corresponding to the column relating to the system control pixel. A vertical signal line is selected and the first signal line is selected. The first horizontal scanning circuit for driving the transfer switch and the first vertical signal line are provided separately from each other, and all the pixels of the pixel portion excluding the system control pixels are set as imaging pixels. A second vertical signal line that outputs a signal from the imaging pixel; a second vertical scanning circuit that selects a row related to the imaging pixel that outputs a signal to the second vertical signal line; and the imaging A second signal reading unit that outputs a signal related to the pixel for use to the outside, a second transfer switch that connects the second vertical signal line and the second signal reading unit, and a pixel that relates to the imaging pixel The solid-state imaging device is configured to include a second horizontal scanning circuit that selects the second vertical signal line corresponding to the column and drives the second transfer switch.

  The invention according to claim 2 is the solid-state imaging device according to claim 1, further comprising well potential fixing means for electrically fixing the common well of the pixel to a constant potential, wherein the system control pixel is the well. The pixel includes a potential fixing unit.

  The invention according to claim 3 is the solid-state imaging device according to claim 1 or 2, the optical system that forms a subject image on the pixel section of the solid-state imaging device, and the first signal readout of the solid-state imaging device. The image pickup system is configured to include system control means for controlling the focal length of the optical system based on a signal supplied from the unit.

  According to a fourth aspect of the present invention, there is provided a solid-state imaging device according to the first or second aspect, an optical system that forms a subject image on a pixel portion of the solid-state imaging device, and a first signal readout of the solid-state imaging device. An imaging system is configured by including system control means for controlling exposure related to the subject image based on a signal supplied from the unit.

  According to the present invention, the signal output from the system control pixel is transmitted from the first readout unit via the first vertical signal line, and the signal output from the imaging pixel is separated from the first vertical signal line. The signals are output from the second reading unit via the second vertical signal line. As a result, the signal output from the system control pixel and the signal output from the imaging pixel can be read out independently in time, and system control based on the signal output from the system control pixel, for example, focus Control and exposure control can be performed at high speed.

  Next, the best mode for carrying out the present invention will be described.

(Example 1)
The solid-state imaging device according to the present invention performs focus control using a signal from a pixel unit, and can perform an imaging operation at the same time. First, Example 1 will be described. FIG. 1 is a block diagram illustrating a configuration of the solid-state imaging apparatus according to the first embodiment. The solid-state imaging device according to this embodiment includes a pixel unit 11 including pixels including two-dimensionally arranged photoelectric conversion elements, and hatching arranged in a position suitable for focus control in the pixel unit 11. A focus control signal pixel 6, a focus control signal vertical scanning circuit 9 for selecting a readout row of only the focus control signal pixel 6, and a focus control signal for reading an output signal from the focus control signal pixel 6. A focus control signal horizontal scanning circuit 8 for selecting a pixel signal from a pixel in a row selected by the vertical signal line 10 for use, the focus control signal vertical scanning circuit 9 via the transfer switch 13, and for the focus control signal. A focus control signal readout unit 7 that reads out the signal of the focus control signal pixel 6 selected by the horizontal scanning circuit 8, and further, an imaging pixel that is all pixels excluding the focus control signal pixel 6 from the pixel unit 11. 1 and The imaging signal vertical scanning circuit 4 for selecting the readout row of the imaging pixel 1, the imaging signal vertical signal line 5 for reading out the output from the imaging pixel 1, and the imaging signal vertical scanning circuit 4. The imaging signal horizontal scanning circuit 3 for reading out the pixel signals of the pixels in the selected row via the transfer switch 12, and the imaging pixel 1 selected by the imaging signal vertical scanning circuit 4 and the imaging signal horizontal scanning circuit 3 And an imaging signal readout unit 2 for reading out the above signals.

  Next, the operation of the solid-state imaging device according to the first embodiment configured as described above will be described. First, the row position of the imaging pixel 1 in the pixel section 11 is designated by the imaging signal vertical scanning circuit 4 for the imaging pixel 1. By sequentially turning on the transfer switch 12 by the imaging signal horizontal scanning circuit 3 for the row position designated by the imaging signal vertical scanning circuit 4, the signal from the imaging pixel 1 is transmitted via the vertical signal line 5. Transfer to the imaging signal readout unit 2. After all the pixel signals from the imaging pixels for one row are transferred, the next row is selected by the imaging signal vertical scanning circuit 4. Thereafter, by operating the imaging signal horizontal scanning circuit 3 in the same manner, the pixel signals of the imaging pixels in the designated row are transferred to the imaging signal reading unit 2, and this operation is performed for imaging in the first row of the pixel unit 11. By repeating from the pixel to the imaging pixel in the last row, all the signals of the imaging pixel can be read out.

  The focus control signal pixel 6 also includes a dedicated focus control signal vertical scanning circuit 9, a focus control signal vertical signal line 10, a focus control signal horizontal scanning circuit 8, a transfer switch 13, and a focus control signal readout unit 7. The row selection by the focus control signal vertical scanning circuit 9 and the transfer to the focus control signal reading unit 7 by the focus control signal horizontal scanning circuit 8 are performed in the same manner as the reading of the pixel signal of the imaging pixel 1.

  As described above, in this embodiment, the path from the imaging pixel 1 to the imaging signal readout unit 2 and the path from the focus control signal pixel 6 to the focus control signal readout unit 7 are completely physically independent. Therefore, reading can be performed under independent control.

  Next, an imaging system using the solid-state imaging device according to the first embodiment having the above-described configuration shown in FIG. 1 will be described with reference to FIG. As shown in FIG. 2, the focus control signal 25 output from the solid-state imaging device 21 is input to the AF detection circuit 22. The AF detection circuit 22 calculates the control amount of the lens unit 24 based on the focus control signal, and the control amount is transferred to the control signal generator 23. The lens unit 24 is controlled by the control signal from the control signal generator 23. The focus control adjustment is performed by driving. The imaging signal from the imaging pixel of the solid-state imaging device 21 is output independently from the output terminal 26. The imaging pixel 1 and the focus control signal pixel 6 in the pixel unit 11 of the solid-state imaging device 21 have a small number of focus control signal pixels 6 and the readout unit is independent as described above. Focus control can be realized. Here, focus control has been described as system control in the imaging system. However, for exposure control, system control pixels such as those for focus control signals are used as exposure control signal pixels, and are output from the solid-state imaging device as exposure control signals. This signal can be fed back to the shutter speed and aperture control.

(Example 2)
Next, a second embodiment of the solid-state imaging device according to the present invention will be described. First, the pixel configuration of the imaging pixel and the focus control signal pixel in the pixel unit according to the second embodiment will be described. FIG. 3 schematically shows the structure of the imaging pixel. As shown in FIG. 3, the signal charge of the photoelectric conversion element of the pixel is accumulated between the P well 31 and the N-type layer 32 disposed on the P well 31. This charge is read out to the charge storage section (FD) 35 by turning on the voltage applied to the gate 34 of the transfer transistor 33. In FIG. 3, 30 is an N-type substrate, and 36 is a reset transistor for resetting the charge storage portion (FD) 35. In addition, the P ⁺ -type impurity layer on the surface of the photodiode portion has an Si-SiO ₂ interface on the surface of the light receiving portion of the photodiode, and crystal defects are likely to occur. Therefore, this is to suppress this.

  Here, since the potential of the P well 31 is connected to GND around the pixel portion, the potential is the GND potential. However, when the pixel size is increased, a potential difference is generated in the P well due to an imaging operation. This causes shading. In Example 2, for the purpose of stabilizing the potential of the pixel portion 11 and preventing shading, the well contacts 37 are provided in a plurality of pixels in the pixel portion 11 as shown in FIG. The well contact pixel 6a is used as a focus control signal pixel. The reason why the well contact pixel is used as the focus control signal pixel is that the normal well contact pixel has a contact region for stabilizing the potential, and therefore the region of the light receiving portion is narrowed, which is larger than that of the normal pixel. This is because the characteristics are inferior and are not used as imaging pixels.

  Next, the configuration of the solid-state imaging device according to the second embodiment will be described with reference to the block configuration diagram shown in FIG. The pixel portion 11 is composed of a pixel 1 not provided with a well contact and a well contact pixel 6a provided with a well contact arranged at an appropriate interval, and the pixel 1 without a well contact is used as an imaging pixel. Using the well contact pixel 6a as a focus control signal pixel, the signal from the imaging pixel 1 is the imaging signal vertical scanning circuit 4, the imaging signal vertical signal line 5, and the imaging signal horizontal scanning, as in the first embodiment. The signals from the well contact pixel 6a as the focus control signal pixel are output from the circuit 3 and the imaging signal readout unit 2, and the focus control signal vertical scanning circuit 9, the focus control signal vertical signal line 10, the focus. The control signal horizontal scanning circuit 8 and the focus control signal reading unit 7 output the signals.

  Also in the second embodiment having such a configuration, compared to conventional focus control using a solid-state imaging device that needs to read out all pixels, focusing can be performed at high speed, and shading can be prevented from occurring. Focus control can be realized well. As in the first embodiment, for exposure control when the imaging system is configured, a well contact pixel as a system control pixel for a focus control signal is used as an exposure control signal pixel, and the exposure control signal is solid. This can be realized by feeding back the signal output from the imaging device to the shutter speed and aperture control.

1 is a block configuration diagram illustrating a configuration of a first embodiment of a solid-state imaging device according to the present invention. FIG. It is a block block diagram which shows the structure of the imaging system using the solid-state imaging device shown in FIG. 6 is a schematic cross-sectional view illustrating a configuration of an imaging pixel in a pixel unit of a solid-state imaging device according to Embodiment 2. FIG. FIG. 6 is a schematic cross-sectional view illustrating the configuration of well contact pixels in a pixel portion of the solid-state imaging device according to the second embodiment. FIG. 6 is a block configuration diagram illustrating an overall configuration of a solid-state imaging apparatus according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging pixel 2 Imaging signal readout part 3 Imaging signal horizontal scanning circuit 4 Imaging signal vertical scanning circuit 5 Imaging signal vertical signal line 6 Focus control signal pixel 6a Well contact pixel 7 Focus control signal readout part 8 Focus control signal Horizontal scanning circuit 9 Vertical control circuit for focus control signal
10 Vertical signal line for focus control signal
11 Pixel section
12 Image signal transfer switch
13 Focus control signal transfer switch
21 Solid-state imaging device
22 AF detection circuit
23 Control signal generator
24 Lens unit
25 Focus control signal
26 Image signal output terminal
30 N-type substrate
31 P-well
32 N-type layer
33 Transfer transistor
34 Gate
35 Charge storage unit
36 Reset transistor
37 Well contact

Claims (4)

A plurality of two-dimensional pixels each including a photoelectric conversion element including a common well made of a first conductive type semiconductor and a second conductive type semiconductor different from the first conductive semiconductor formed in the common well. Pixel parts arranged in a shape,
A first vertical signal line from which signals from system control pixels set at a plurality of specific positions in the pixel portion are output;
A first vertical scanning circuit for selecting a row related to the system control pixel that outputs a signal to the first vertical signal line;
A first signal readout unit for outputting a signal related to the system control pixel to the outside;
A first transfer switch connecting the first vertical signal line and the first signal readout unit;
A first horizontal scanning circuit that selects the first vertical signal line corresponding to the column relating to the system control pixel and drives the first transfer switch;
The second vertical signal line is provided separately from the first vertical signal line, and all pixels of the pixel unit excluding the system control pixel are used as imaging pixels, and at least a signal from the imaging pixel is output. A vertical signal line;
A second vertical scanning circuit for selecting a row related to the imaging pixel that outputs a signal to the second vertical signal line;
A second signal readout unit for outputting a signal related to the imaging pixel to the outside;
A second transfer switch connecting the second vertical signal line and the second signal readout unit;
A solid-state imaging device comprising: a second horizontal scanning circuit that selects the second vertical signal line corresponding to the column relating to the imaging pixel and drives the second transfer switch.   2. The system according to claim 1, further comprising well potential fixing means for electrically fixing the common well of the pixel to a constant potential, wherein the system control pixel is a pixel provided with the well potential fixing means. Such a solid-state imaging device.   The solid-state imaging device according to claim 1 or 2, an optical system that forms a subject image on a pixel unit of the solid-state imaging device, and a signal supplied from a first signal readout unit of the solid-state imaging device. And an image pickup system having system control means for controlling the focal length of the optical system.   The solid-state imaging device according to claim 1 or 2, an optical system that forms a subject image on a pixel unit of the solid-state imaging device, and a signal supplied from a first signal readout unit of the solid-state imaging device. An imaging system comprising system control means for controlling exposure related to the subject image.

Images