JPH07203313A - Solid state image pickup device - Google Patents

Abstract

PURPOSE:To remove unevenness in the luminance of a screen due to a characteristic difference between an FDA and a preamplifier in each divided area by automatically controlling the mean value of respective video signals at a fixed value in a solid state image pickup device for synthesizing the outputs of plural divided and read photodetection elements and outputting a video signal. CONSTITUTION:Signal charge generated by an optical signal made incident upon a photodetector 1 is respectively converted into signal voltage components by 1st and 2nd FDAs 4, 5, amplified to required voltage levels by 1st and 2nd preamplifiers 6, 7 and then double sampled by 1st and CDSs 8, 9. The mean value of these analog video signals is always controlled to a fixed value by 1st and 2nd video level control circuits 16, 17, so that a signal voltage difference generated due to a characteristic difference between the FDA and the preamplifier in each divided area can be compensated.

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 which divides a light receiving region of a photodetector into a plurality of regions and reads them out, and outputs a video signal synthesized on a screen by a synthesis circuit.

[0002]

2. Description of the Related Art As a conventional example of a solid-state image pickup device, light-receiving regions of photodetectors are arranged line by line.
Description will be made on the basis of a two-division read solid-state image pickup device which reads out the output of each of the odd field element array and the even field element array separately. FIG. 6 is a block diagram showing an example of a conventional solid-state image pickup device. Reference numeral 1 is a photodetector for separately reading an odd field element array and an even field element array in a light receiving region, and 2 is a first odd field element array.
Divided areas (hereinafter, referred to as first divided areas), 3 is a second divided area (hereinafter, referred to as second divided area) that corresponds to an even field element row, and 4 is a first floating diffusion amplifier (hereinafter, first FDA). 5 is a second floating diffusion amplifier (hereinafter referred to as the second FDA).
6) is a first preamplifier (hereinafter referred to as a first preamplifier), 7 is a second preamplifier (hereinafter referred to as a second preamplifier), and 8 is a first double sampling circuit (hereinafter referred to as a first CDS). , 9 is a second double sampling circuit (hereinafter referred to as a second CDS), and 10 is a first A /
D conversion circuit (hereinafter referred to as the first A / D conversion circuit), 11
Is a second A / D conversion circuit (hereinafter referred to as a second A / D conversion circuit), 12 is a combining circuit, 13 is a correction circuit, and 14 is D /
An A conversion circuit, 15 is a monitor.

Next, the operation will be described. The signal charges generated in the first divided region 2 and the second divided region 3 by the optical signal incident on the photodetector 1 are converted into signal voltages by the first FDA 4 and the second FDA 5 and output. The output signal voltage is amplified to a desired voltage by the first preamplifier 6 and the second preamplifier 7, respectively. The amplified video signal is double-sampled by the first CDS 8 and the second CDS 9, respectively for noise cancellation. The double-sampled video signals are converted into digital video signals by the first A / D conversion circuit 10 and the second A / D conversion circuit 11, respectively, and are combined into one screen by the combining circuit 12. The combined digital video signal is subjected to correction processing in the correction circuit 13 and then in the D / A conversion circuit 14.
It is converted into an analog video signal and displayed on the monitor 15.

[0004]

Since the conventional solid-state image pickup device is constructed as described above, the FDA and the preamplifier are independent for each divided area. Therefore, when there is a difference in the characteristics (FDA output characteristic, preamplifier gain characteristic, etc.), a difference occurs in the signal voltage in each divided region. This has the drawback that it appears as a difference in brightness on the screen.

The present invention has been made in order to solve such a problem, and an object thereof is to automatically eliminate non-uniformity of brightness in a screen due to a difference in characteristics of FDA and preamplifier in each divided area. .

[0006]

The solid-state image pickup device according to the present invention comprises a video level control circuit for automatically controlling the average voltage level of an analog video signal to a constant value.

A solid-state image pickup device according to another embodiment includes a video level average value detection circuit for detecting an average voltage level of an analog video signal in a certain division area, and another division for the detected video level average voltage. It is provided with a video level control circuit for adjusting the average level of analog video signals in the area.

A solid-state image pickup device according to still another embodiment includes a video level control circuit for automatically controlling the average level of a digital video signal to a constant value.

In a solid-state image pickup device according to still another embodiment, a video level average value detection circuit for detecting the average level of a digital video signal in a certain divided area, and another division for the detected video level average value. It is provided with a video level control circuit for matching the digital video signals in the area.

Further, in a solid-state image pickup device according to still another embodiment, after synthesizing the digital video signals of the divided areas for each field element array by a synthesizing circuit, the average of the digital video signals of each field is obtained. It is provided with a video level control circuit for automatically controlling the level to a constant value.

[0011]

In the solid-state image pickup device according to the present invention, by controlling the average voltage of the analog video signal after double sampling to a constant value by the video level control circuit,
The signal voltage difference caused by the characteristic difference between the FDA and the preamplifier in each divided area is corrected to prevent the luminance difference from occurring in the screen.

In a solid-state image pickup device according to another embodiment, a video level average value detection circuit detects an analog video signal average voltage after double sampling in a certain divided area, and the analog video signal in another divided area is detected. The average value
By controlling so that it becomes the same as the average voltage detected by the video level control circuit, the signal voltage difference caused by the characteristic difference between the FDA and the preamplifier in each divided region is corrected,
This is to prevent a difference in brightness from occurring on the screen.

In the solid-state image pickup device according to still another embodiment, the average value of the digital video signal after A / D conversion is controlled to be a constant value by the video level control circuit, so that each divided area The signal voltage difference caused by the characteristic difference between the FDA and the preamplifier is corrected to prevent the luminance difference from occurring in the screen.

In a solid-state image pickup device according to still another embodiment, a video level average value detection circuit detects an average value of a digital video signal after A / D conversion of a certain divided area,
By controlling the average value of the digital video signals in the other divided areas to be the same as the average value detected by the video level control circuit, the signal voltage difference caused by the characteristic difference between the FDA and the preamplifier in each divided area is eliminated. The correction is performed to prevent a difference in brightness from occurring on the screen.

Further, in a solid-state image pickup device according to still another embodiment, after synthesizing the digital video signals of the respective divided regions for each field element row by a synthesizing circuit,
By controlling the average value of the digital video signal of each field to a constant value by the video level control circuit,
The signal voltage difference caused by the characteristic difference between the FDA and the preamplifier in each divided area is corrected to prevent the luminance difference from occurring in the screen.

[0016]

【Example】

Embodiment 1 FIG. 1 is a block diagram showing an embodiment of the solid-state image pickup device according to the present invention. In the figure, 1 to 15 are the same as the conventional embodiment. Reference numeral 16 is a first video level control circuit, and 17 is a second video level control circuit.

Next, the operation will be described. The signal charge generated in the first divided region 2 and the second divided region 3 by the optical signal incident on the photodetector 1 is converted into a signal voltage by the first FDA4 and the second FDA5, respectively, and the signal voltage is output. It is amplified to a desired voltage by the second preamplifier 7. The amplified video signal is double-sampled by the first CDS 8 and the second CDS 9 for noise cancellation, as in the conventional device. The average value of the analog video signal after the double sampling is always controlled to a constant value by the first video level control circuit 16 and the second video level control circuit 17, respectively.
As a result, the first divided area 2 and the second divided area 3
The signal voltage difference caused by the characteristic difference between the FDA and the preamplifier is corrected. This corrected analog video signal,
The first A / D conversion circuit 10 and the second A / D conversion circuit 11 respectively convert the signals into digital video signals, and the combination circuit 12 combines them into one screen. The combined digital video signal is subjected to correction processing in the correction circuit 13 and converted into an analog video signal in the D / A conversion circuit 14. Since this signal is displayed on the monitor 15, there is no difference in brightness between the divided areas in the screen.

Embodiment 2 FIG. 2 is a block diagram showing an embodiment of a solid-state image pickup device according to another invention, in which 1 to 15 are the same as the conventional embodiment. 18 is a video level average value detection circuit, 19
Is a video level control circuit.

Next, the operation will be described. The signal charge generated in the first divided region 2 and the second divided region 3 by the optical signal incident on the photodetector 1 is converted into a signal voltage by the first FDA4 and the second FDA5, respectively, and the signal voltage is output. It is amplified to a desired voltage by the second preamplifier 7. The amplified video signal is double-sampled by the first CDS 8 and the second CDS 9 for noise cancellation, as in the conventional device. In the video level average value detection circuit 18, the first divided area 2
Of the analog video signal average voltage after double sampling is detected, and in the video level control circuit 19, the average value of the analog video signal after double sampling of the second divided region 3 is detected by the video level average value detection circuit 18. Same as the value. As a result, the signal voltage difference caused by the characteristic difference between the FDA and the preamplifier in the first divided area 2 and the second divided area 3 is corrected. The corrected analog video signal is supplied to the first A / D conversion circuit 1 respectively.
0, the second A / D conversion circuit 11 converts it into a digital video signal, and the synthesizing circuit 12 synthesizes it into one screen. The combined digital video signal is subjected to correction processing in the correction circuit 13 and converted into an analog video signal in the D / A conversion circuit 14. Since this signal is displayed on the monitor 15, there is no difference in brightness between the divided areas in the screen.

Embodiment 3 FIG. 3 is a block diagram showing an embodiment of a solid-state image pickup device according to yet another invention. In the figure, 1 to 15 are the same as the conventional embodiment. 20 is a first video level control circuit,
Reference numeral 21 is a second video level control circuit.

Next, the operation will be described. The signal charges generated in the first divided region 2 and the second divided region 3 by the optical signal incident on the photodetector 1 are converted into signal voltages by the first FDA 4 and the second FDA 5 and output. The output signal voltage is amplified to a desired voltage by the first preamplifier 6 and the second preamplifier 7, respectively. The amplified video signal is double-sampled by the first CDS 8 and the second CDS 9, respectively, for noise cancellation. The process of converting the double-sampled video signal into a digital video signal by the first A / D conversion circuit 10 and the second A / D conversion circuit 11, respectively, is the same as in the conventional device. The average value of the digital video signal after the A / D conversion is always controlled to a constant value by the first video level control circuit 20 and the second video level control circuit 21, respectively. As a result, the FDA of the first divided area 2 and the second divided area 3
And the signal voltage difference caused by the characteristic difference of the preamplifier is corrected. The corrected digital video signal is combined by the combining circuit 12 into one screen. The combined digital video signal is subjected to correction processing in the correction circuit 13, and D /
The A conversion circuit 14 converts the analog video signal.
Since this signal is displayed on the monitor 15, there is no difference in brightness between the divided areas in the screen.

Embodiment 4 FIG. 4 is a block diagram showing an embodiment of a solid-state image pickup device according to yet another invention. In the figure, 1 to 15 are the same as the conventional embodiment. 22 is a video level average value detection circuit, and 23 is a video level control circuit.

Next, the operation will be described. The signal charges generated in the first divided region 2 and the second divided region 3 by the optical signal incident on the photodetector 1 are converted into signal voltages by the first FDA 4 and the second FDA 5 and output. The output signal voltage is amplified to a desired voltage by the first preamplifier 6 and the second preamplifier 7, respectively. The amplified video signal is double-sampled by the first CDS 8 and the second CDS 9, respectively, for noise cancellation. The process of converting the double-sampled video signal into a digital video signal by the first A / D conversion circuit 10 and the second A / D conversion circuit 11, respectively, is the same as in the conventional device. The video level average value detection circuit 22 detects the digital video signal average value of the first divided area 2 after A / D conversion, and the video level control circuit 23 detects the digital value of the second divided area 3 after A / D conversion. The average level of the video signal is made the same as the value detected by the video level average value detection circuit 22. As a result, the signal voltage difference caused by the characteristic difference between the FDA and the preamplifier in the first divided area 2 and the second divided area 3 is corrected. The corrected digital video signal is combined by the combining circuit 12 into one screen. The combined digital video signal is subjected to correction processing in the correction circuit 13 and converted into an analog video signal in the D / A conversion circuit 14. Since this signal is displayed on the monitor 15, there is no difference in brightness between the divided areas in the screen.

Embodiment 5 FIG. 5 is a block diagram showing an embodiment of a solid-state image pickup device according to yet another invention. In the figure, 1 to 15 are the same as the conventional embodiment. Reference numeral 24 is a video level control circuit.

Next, the operation will be described. The signal charges generated in the first divided region 2 and the second divided region 3 by the optical signal incident on the photodetector 1 are converted into signal voltages by the first FDA 4 and the second FDA 5 and output. The output signal voltage is amplified to a desired voltage by the first preamplifier 6 and the second preamplifier 7, respectively. The amplified video signal is double-sampled by the first CDS 8 and the second CDS 9, respectively, for noise cancellation. The double-sampled video signal is converted into a digital video signal by the first A / D conversion circuit 10 and the second A / D conversion circuit 11, respectively, and the digital video signal of each divided region divided for each field element row is The process of synthesizing by the synthesizing circuit 12 is the same as the conventional device. The average value of the digital video signal of each field is always controlled to a constant value by the video level control circuit 24. This makes the first
The signal voltage difference caused by the characteristic difference between the FDA and the preamplifier in the divided area 2 and the second divided area 3 is corrected. The digital video signal is corrected in the correction circuit 13 and converted into an analog video signal in the D / A conversion circuit 14. Since this signal is displayed on the monitor 15, there is no difference in brightness between the divided areas on the screen.

[0026]

As described above, according to the present invention, by arranging the average values of the video signals of each divided area, the unevenness of the brightness in the screen caused by the difference in the FDA and preamplifier characteristics of each divided area is automatically detected. It has the effect of eliminating it.

[Brief description of drawings]

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

FIG. 2 is a diagram showing the configuration of another embodiment of the solid-state imaging device according to the present invention.

FIG. 3 is a diagram showing the configuration of yet another embodiment of the solid-state imaging device according to the present invention.

FIG. 4 is a diagram showing the configuration of yet another embodiment of the solid-state imaging device according to the present invention.

FIG. 5 is a diagram showing the configuration of yet another embodiment of the solid-state imaging device according to the present invention.

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

[Explanation of symbols]

 1 Photodetector 2 1st division area 3 2nd division area 4 1st FDA 5 2nd FDA 6 1st preamplifier 7 2nd preamplifier 8 1st CDS 9 2nd CDS 10 1st A / D conversion circuit 11 2nd A / D conversion circuit 12 Compositing Circuit 13 Correction circuit 14 D / A conversion circuit 15 Monitor 16 First video level control circuit 17 Second video level control circuit 18 Video level average value detection circuit 19 Video level control circuit 20 First video level control circuit 21 Second video level Control circuit 22 Video level average value detection circuit 23 Video level control circuit 24 Video level control circuit

Claims (5)

[Claims] 1. A photodetector for dividing a light-receiving region into a plurality of regions for reading, a plurality of preamplifiers connected to each of the plurality of light-receiving regions of the photodetector for amplifying respective output signals, and the plurality of preamplifiers. Connected to the plurality of double sampling circuits for double sampling each output signal, a plurality of video level control circuits connected to the plurality of double sampling circuits for controlling respective output video levels to a constant value, and the plurality of video A plurality of A / D conversion circuits connected to the level control circuit for A / D converting the respective output signals, a combination circuit connected to the plurality of A / D conversion circuits for combining the respective output digital signals, and the above combination A correction circuit connected to the circuit to correct the output digital signal, and a correction circuit connected to the correction circuit to convert the output digital signal to D / A. D / A conversion circuit for converting
A solid-state image pickup device comprising: a monitor connected to the A / A conversion circuit and displaying an output signal thereof. 2. A photodetector for dividing a light receiving region into a plurality of regions for reading, a plurality of preamplifiers connected to each of the plurality of light receiving regions of the photodetector for amplifying respective output signals, and the plurality of preamplifiers. A plurality of double sampling circuits each of which is connected to the double sampling circuit for sampling each output signal, and a video level average value detection circuit which is connected to one of the plurality of double sampling circuits and detects an average value of the output video level, An A / D conversion circuit connected to the double sampling circuit for A / D converting the output signal thereof, and a plurality of other double sampling circuits and the video level average value detection circuit connected to the output video levels of the plurality of double sampling circuits. And a plurality of video level control circuits for controlling the average value detected by the video level average value detection circuit, A plurality of A / D conversion circuits connected to the plurality of video level control circuits for A / D converting each output signal, and a combination circuit connected to all the A / D conversion circuits and combining the output digital signals A correction circuit connected to the synthesizing circuit for correcting the output digital signal, a D / A conversion circuit connected to the correction circuit for D / A converting the output digital signal, and connected to the D / A conversion circuit. A solid-state imaging device comprising: a monitor that displays the output signal. 3. A photodetector for dividing a light receiving area into a plurality of areas for reading, a plurality of preamplifiers connected to each of the plurality of light receiving areas of the photodetector for amplifying respective output signals, and the plurality of preamplifiers. Connected to the plurality of double sampling circuits for double sampling each output signal, a plurality of A / D conversion circuits connected to the plurality of double sampling circuits for A / D converting each output signal, and the plurality of A A plurality of video level control circuits connected to the D / D conversion circuit and controlling respective output digital video levels to a constant value; a combination circuit connected to the plurality of video level control circuits and combining the respective output digital signals; A correction circuit connected to the combining circuit to correct the output digital signal, and a correction circuit connected to the correction circuit to output the output digital signal A solid-state imaging device comprising: a D / A conversion circuit for D / A conversion; and a monitor connected to the D / A conversion circuit and displaying an output signal thereof. 4. A photodetector for dividing a light receiving area into a plurality of areas for reading, a plurality of preamplifiers connected to each of the plurality of light receiving areas of the photodetector for amplifying respective output signals, and a plurality of preamplifiers. Connected to the plurality of double sampling circuits for double sampling the respective output signals, a plurality of A / D conversion circuits connected to the plurality of double sampling circuits for A / D converting the respective output signals, and a plurality of A / D conversion circuits. A video level average value detection circuit connected to one of the D conversion circuits to detect the average value of the output digital video level, and the video level average value detection circuit and the plurality of other A / D conversion circuits connected to each other. A /
A plurality of video level control circuits for controlling the output digital signal of the D conversion circuit to the average value detected by the video level average value detection circuit, and an A / D conversion circuit connected to the video level average value detection circuit. A synthesizing circuit connected to the plurality of video level control circuits for synthesizing output digital signals of the respective circuits, a correction circuit connected to the synthesizing circuit for correcting the output digital signals, and a output connected to the correction circuit D for D / A conversion of digital signals
A solid-state image pickup device comprising: an A / A conversion circuit; and a monitor connected to the D / A conversion circuit and displaying an output signal thereof. 5. A photodetector for reading by dividing a light receiving region into a plurality of fields for each field element row, and a light detector connected to each of the plurality of light receiving areas divided for each field element row of the photodetector. A plurality of preamplifiers for amplifying signals, a plurality of double sampling circuits connected to the plurality of preamplifiers for double sampling each output signal, and a plurality of double sampling circuits connected to the plurality of double sampling circuits for A / D conversion of each output signal A plurality of A / D conversion circuits, a combination circuit that is connected to the plurality of A / D conversion circuits and combines the output digital signals, and an average of the digital video signals of each field that is the output that is connected to the combination circuit A video level control circuit for controlling the value to a constant value and an output digital signal connected to the video level control circuit. And a correction circuit that is connected to the correction circuit and D / A converts the output digital signal of the correction circuit.
A solid-state image pickup device comprising: an A / A conversion circuit; and a monitor connected to the D / A conversion circuit and displaying an output signal thereof.