JPH0720219B2 - Driving method for photoelectric conversion device - Google Patents

Description

The present invention relates to a method for driving a photoelectric conversion device, more specifically, a step of irradiating a plurality of photoelectric conversion elements with light and accumulating carriers in the plurality of photoelectric conversion elements. And a method for driving a photoelectric conversion device including a step of reading an optical signal based on the accumulated carriers from each photoelectric conversion element, and a step of performing a refresh operation for removing the carriers accumulated in the plurality of photoelectric conversion elements. It is a thing.

[Prior Art] Conventionally, a TV camera using an image sensor such as CCD or MOS,
Some SV cameras have a diaphragm function. As photoelectric conversion devices equipped with such a TV camera and SV camera having an automatic aperture function, there are photoelectric conversion devices described in JP-A-60-12759 to JP-A-60-12765. .

This photoelectric conversion device comprises an optical sensor section in which a plurality of optical sensor cells having carriers are arranged on a control electrode of a semiconductor transistor.

FIG. 3 is a circuit diagram of the photoelectric conversion device, and FIG. 4 is a diagram showing its timing chart.

In these figures, the capacitor electrodes 101 ... Of the optical sensor cells 100 ... Are commonly connected to the drive line, and the collector electrodes 102 ... Are commonly connected to the positive voltage terminal.

The drive terminal is connected to the drive line.

A pulse signal for driving the optical sensor cell 100 ... Is applied to the drive terminal, and the emitter terminal 103 ... Of the optical sensor cell 100 ... is connected to a vertical signal line. It is commonly connected through the reset FET 104 ... And is also connected to the ground terminal GND.

Further, the gate electrodes of the FETs 104 ... Are commonly connected to the reset terminal.

FET 104 ... Is a field effect transistor for switching.

The vertical signal line is connected to the storage capacitor 106 ... Through the FET 105 ... and also connected to the source electrode of the FET 107 ..., and the drain electrode of the FET 107 ... Is common to the horizontal signal line. And the gate electrode of the FET 105 is commonly connected to the control terminal.

The gate electrode of the FET 107 is connected to the output terminal of the scanning circuit 108.

The horizontal signal line is connected to the external output terminal via the output amplifier 109 and also connected to the ground terminal GND via the FET 110.

Further, the gate terminal of the FET 110 is connected to the reset terminal.

The FET 110 used here is a field effect transistor for resetting a horizontal line.

Next, the driving method of the circuit of FIG. 3 will be described with reference to the timing chart of FIG.

First, both the control terminal and the reset terminal are set to H level. Then, during the reset period, the storage capacitor 106 ...
The optical signal stored in is reset.

When the control terminal is at the H level and the reset terminal is at the L level, the pulse signal for reading is applied to the drive terminal to read out the optical signal accumulated in the optical sensor cells 100. The optical signal is read out on the signal line and stored in the storage capacitors 106 ...

In this way, the reading of the photosensor cells 100 ... Starts when the reading pulse signal is at the H level, and the reading pulse signal becomes the L level and the reading ends after a lapse of a predetermined period.

When the control terminal is at the L level and the reset terminal is at the H level, the refresh operation state is set, and the optical sensor cell 100
The optical signal stored in ... Is erased.

Then, the pulse signal for refresh becomes L level and the refresh operation is completed.

That is, the period until the next read operation state is reached is the accumulation period for accumulating carriers in the photosensor cell 100.

The pulse signal from each output terminal of the scanning circuit 108 is
The FET 107 is sequentially turned on according to the shift timing.

By the horizontal scanning of the scanning circuit 108, the storage capacitor 106
The optical signals stored in ... Are read serially on the horizontal line, amplified by the output amplifier 109, and then output from the external output terminal.

When the reading of all the optical signals stored in the storage capacitors 106 ... Is completed in this way, the process returns to the first reset period again.

Then, the above operation is repeated.

[Problems to be Solved by the Invention] In the above-described method for driving the photoelectric conversion device, the output signal read from the photosensor cell is noisy due to the variation of the dark voltage generated in the photosensor cell at any storage time. May be included.

Therefore, conventionally, an output signal corresponding to the dark current generated in the photosensor cell is stored in advance in the external storage device as a reference light signal, and the reference output signal from this reference light signal and the actual read signal from the light sensor cell are read. There is a method in which correction is performed by comparing output signals of optical signals to remove a noise component due to dark voltage.

However, in such a conventional photoelectric conversion device, when attempting to systemize the photoelectric conversion device, there is a problem that the system becomes more complicated because an external circuit is separately required.

The present invention has been made in view of the above circumstances, and includes a dark voltage signal storage unit that stores a dark voltage signal read from a photoelectric conversion element together with an optical signal storage unit that stores an optical signal read from a photoelectric conversion element, By simultaneously reading the actual optical signal stored in the optical signal storage means and the dark voltage signal stored in the dark voltage signal storage means on separate output lines, the signal corresponding to the dark voltage is optically read. The purpose is to correct for each sensor cell and remove the noise due to the variation of the dark voltage from the output signal.

[Means for Solving Problems] In order to solve the above problems, the present invention includes a step of irradiating a plurality of photoelectric conversion elements with light to accumulate carriers in the plurality of photoelectric conversion elements. A step of reading an optical signal based on the carrier from each photoelectric conversion element and accumulating it in the optical signal accumulating means; a step of performing a refresh operation for removing the carriers accumulated in the plurality of photoelectric conversion elements; A step of reading a dark voltage signal from each photoelectric conversion element in a state where the element is shielded and accumulating it in the dark voltage signal accumulating means; And a step of respectively outputting a signal and the dark voltage signal, and a method for driving a photoelectric conversion device, comprising:

[Operation] According to the method described above, the dark voltage signal stored in the dark voltage signal storage means is simultaneously read on the separate information output lines, and the dark voltage signal is corrected for each photosensor cell. The noise caused by the variation of is removed.

Therefore, since noise corresponding to the dark voltage can be processed in the sensor, an external circuit or the like is not required, the system configuration can be simplified, and a low-cost photoelectric conversion device can be provided.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a circuit diagram showing an example of a photoelectric conversion device using the present invention.

In this figure, reference numeral 1 is a photosensor cell which is a photoelectric conversion element, and the photosensor cells 1 are arranged one-dimensionally.

The capacitor electrode 2 of the photosensor cell 1 is commonly connected to the drive line and is also connected to the drive terminal, and the collector electrode 3 of the photosensor cell 1 is commonly connected to the positive voltage terminal.

In addition, the emitter electrode 4 of the optical sensor cell 1 has a vertical line 5
The vertical line 5 is commonly connected via the FET 6, and the FET 6 is connected to the ground terminal 7.

A reset terminal is commonly connected to the gate electrode of the FET 6.

The vertical line 5 is connected to the capacitor 9 and FE via the FET 8.
The source electrode of T10 is connected, and the capacitor 9 is connected to the earth terminal 12 via the earth line 11.

The capacitor 9 is a capacitor for storing an optical signal.

The gate electrode of the FET 10 is connected to the output terminal 14 of the scanning circuit 13, and the drain electrode of the FET 10 is connected to the output amplifier 16 via the horizontal line 15. The output side of the output amplifier 16 is connected to the external output terminal 17, and the output voltage is taken out from the external output terminal 17.

The gate electrode of the FET 10 is also connected to the gate electrode of the FET 18, and the drain electrode of the FET 18 is connected to the output amplifier 20 via the output line 19.

The output side of the output amplifier 20 is connected to the external output terminal 21, and the output voltage is taken out from the external output terminal 21.

Further, the source electrode of the FET 18 is also connected to the vertical line 5 via the FET 22.

In addition to the above, in the present embodiment, one electrode portion of the capacitor 24 is connected between the source electrode of the FET 18 and the FET 22 through the vertical line 23, and the other electrode portion of the capacitor 24 is connected to the earth line 11. ing.

This capacitor 24 is a capacitor for dark voltage signal storage.

Next, the operation of this embodiment will be described.

As shown in the timing chart of FIG. 2, the optical sensor cells 1 ... Accumulate an optical signal according to the light amount by the optical accumulation operation in the light irradiation accumulation period.

First, during the fixed period until the optical signal read-out period,
The photosensor cells 1 ... Accumulate carriers by light irradiation. Then, in the reset period, both the control terminal and the reset terminal become the H level, and the electric charge stored in the capacitor 9 is reset.

Next, when the read terminal pulse voltage is applied to the drive terminal with the control terminal at the H level and the reset terminal at the L level, the optical information stored in the optical sensor cells 1 ... Is read out on the vertical line. It

Then, the optical signal is stored in the capacitor 9.

After the end of the optical signal reading period, if the reset terminal is set to the H level and the refresh pulse voltage is applied to the drive terminal, the optical sensor cells 1 ...
The optical signals accumulated in the optical sensor cells 1 ... Are erased.

After the refresh period ends, the light sensor cells 1 ...

At this time, the dark voltage generated in the dark state is accumulated in the photosensor cells 1 ... Here, the dark voltage accumulation period and the light irradiation accumulation period are set to be the same time.

Next, by setting both the dark voltage read terminal and the reset terminal to the H level, the electric charge stored in the capacitor 24 during the reset period is reset.

The dark voltage signal accumulated in the optical sensor cells 1 ... Is read on the vertical line 5 by setting the dark voltage read terminal to the H level and the reset terminal to the L level, applying the read pulse voltage Er to the drive terminal. put out.

In this way, the dark voltage signal is stored in the capacitor 24.

After the end of the dark voltage reading period, the dark voltage reading terminal is set to L.
The level and reset terminal are set to H level, and the pulse voltage E0 for refresh is applied to the drive terminal to bring the photosensor cells 1 ...

When the refresh pulse voltage is set to the L level after a certain period of time, the refresh period ends and the light shielding period ends, and the reset terminal is set to the L level.

Next, the FET 10 and the FET 18 are sequentially turned on according to the timing at which the output pulse from the output terminal 14 of the scanning circuit 13 shifts.

By this horizontal scanning, the optical signals stored in the capacitor 9 are serially read out on the horizontal line 15. Further, in synchronization with this reading, the dark voltage signal is read on the output line 19.

In this way, the optical signal read on the horizontal line 15 is output to the external output terminal 17 through the output amplifier 16, while the dark voltage signal read on the output line 19 is output by the output amplifier 20.
To the external output terminal 21, and the output voltage is taken out from this external output terminal.

Then, after a fixed period, the horizontal scanning period ends, the reset period returns again, and thereafter, the above operation is repeated.

Since the photoelectric conversion device in this embodiment operates as described above, an additional external circuit such as a conventional photoelectric conversion device is not required to remove noise due to dark voltage, and the system configuration is simple. Therefore, it becomes possible to meet the demand for a low-cost photoelectric conversion device.

In the above embodiment, the actual optical signals simultaneously read on the individual lines and the dark voltage signal are amplified in the output circuit section 25 by using the output amplifiers 16 and 20 and output to the outside. However, the configuration is not limited to such a configuration, and the output circuit unit 25 is replaced with a differential amplifier or the like, and an optical signal corresponding to the actual optical signal minus the dark voltage signal contained therein is output to the outside. It goes without saying that it may be one that has been done.

Further, in this embodiment, the dark voltage accumulation period and the light irradiation period are set at the same time, but the present invention is not limited to this.

For example, by effectively utilizing the relationship between the dark voltage generation amount and the dark voltage storage time in the photosensor cells 1 ..., The dark voltage storage time is made shorter than the light irradiation time, and the output amplifier of the output circuit unit 25 is provided. The gains of 16 and 20 are individually adjusted, or the values of the storage capacitors 9 ..., 24 ... Are adjusted to obtain the same result as the above embodiment. It goes without saying that it is good.

Further, in the present embodiment, the one in which the photosensor cells are arranged one-dimensionally has been described, but it goes without saying that the present invention is not limited to this.

[Effects of the Invention] As described above, a step of irradiating a plurality of photoelectric conversion elements with light to accumulate carriers in the plurality of photoelectric conversion elements, and reading an optical signal based on the accumulated carriers from each photoelectric conversion element The photoelectric signal storage means, a step of performing a refresh operation for removing the carriers stored in the plurality of photoelectric conversion elements, and a step of darkening each photoelectric conversion element in a state where the plurality of photoelectric conversion elements are shielded from light. Reading the voltage signal and accumulating it in the dark voltage signal accumulating means; and outputting the optical signal and the dark voltage signal to a plurality of output lines independent of the optical signal accumulating means and the dark voltage signal accumulating means, respectively. Therefore, when outputting the actual optical signal read from the optical sensor cell to the outside, the signal corresponding to the dark voltage contained therein is corrected for each optical sensor cell, and It is possible to remove noise due to variations in dark voltage. Further, unlike the conventional driving method, an additional external circuit is not required, so that the system configuration can be simplified and it is possible to meet the demand for an economical photoelectric conversion device.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an example of a photoelectric conversion device using the present invention, FIG. 2 is a timing chart diagram thereof, FIG. 3 is a circuit diagram of a photoelectric conversion device, and FIG. 4 is a timing chart thereof. It is a thing. DESCRIPTION OF SYMBOLS 1 is a photoelectric conversion element 2 is a capacitor electrode 9 is an optical information storage means 15, 19 is an information output line 24 is a dark voltage storage means

Claims (5)

[Claims] 1. A step of irradiating a plurality of photoelectric conversion elements with light to accumulate carriers in the plurality of photoelectric conversion elements, and an optical signal accumulating means for reading an optical signal based on the accumulated carriers from each photoelectric conversion element. And a step of performing a refresh operation for removing carriers accumulated in the plurality of photoelectric conversion elements, and reading a dark voltage signal from each photoelectric conversion element with the plurality of photoelectric conversion elements shielded. A step of accumulating in the dark voltage signal accumulating means, and a step of outputting the optical signal and the dark voltage signal to a plurality of output lines independent of the optical signal accumulating means and the dark voltage signal accumulating means, respectively. A method of driving a photoelectric conversion device, which is characterized. 2. The method for driving a photoelectric conversion device according to claim 1, wherein the photoelectric conversion element is a transistor. 3. The method for driving a photoelectric conversion device according to claim 1, wherein the optical signal and the dark voltage signal are amplified and output by an amplifier provided in the plurality of output lines. And a method for driving a photoelectric conversion device. 4. A method of driving a photoelectric conversion device according to claim 1, wherein a signal obtained by subtracting the dark voltage signal from the optical signal is output by an operational amplifier provided in the plurality of output lines. A method for driving a photoelectric conversion device, comprising: 5. A method for driving a photoelectric conversion device according to any one of claims 1 to 4, wherein the photoelectric signal storage means and the dark voltage signal storage means accumulate the light by a scanning circuit. A method of driving a photoelectric conversion device, wherein the optical signal and the dark voltage signal for each photoelectric conversion element are simultaneously output to the plurality of output lines.