JPH0846874A - Driving method for solid-state image pickup device - Google Patents

Abstract

PURPOSE:To keep the time integral value of charge quantity for storage time constant and to prevent flickering and line crawling from occurring. CONSTITUTION:When the signal charge of a solid-state image pickup device provided with four kinds of readout gates is read out in the same field, the signal charge is read out by applying a first readout pulse 11, a second readout pulse 12, a third readout pulse 13 and a fourth readout pulse 14 to the four kinds of readout gates, and the time integral values of two pairs of coupled signal charges can be set equal by coupling the signal charge read out by the first readout pulse 11 with the one read out by the fourth readout pulse 14, and the signal charge read out by the second readout pulse 12 with the one read out by the third readout pulse 13.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art At present, cameras utilizing CCDs are in widespread use, and CCDs capable of realizing high resolution and high function are required. First, a solid-state imaging device using a CCD will be described with reference to FIG. FIG. 2 is a conceptual diagram of the solid-state imaging device. In FIG. 2, reference numeral 1 is a photoelectric conversion element which is two-dimensionally arranged. Reference numeral 2 denotes photoelectric conversion elements 1 that read out signal charges accumulated in the photoelectric conversion element 1 by four types of read gates arranged in the vertical direction. This is a vertical transfer unit in which the conversion elements 1 are paired and two photoelectric conversion elements 1 forming each pair are coupled and transferred in the vertical direction. A horizontal transfer unit 3 transfers the signal charges transferred by the vertical transfer unit 1 in the horizontal direction. An output amplifier unit 4 generates an output signal according to the amount of signal charges transferred by the horizontal transfer unit 3.

Φ1 to φ8 are vertical transfer gates having four types of read gates. The plurality of photoelectric conversion elements 1 are two-dimensionally arranged and accumulate signal charges corresponding to the amount of incident light. The vertical transfer unit 2 is composed of eight-phase vertical transfer gates, and each of the vertical transfer gates is φ1, φ2, φ3.
It is represented by φ4, φ5, φ6, φ7, and φ8. Of these vertical transfer gates φ1 to φ8, φ1, φ3, φ5, and φ7 also serve as read gates for reading out the signal charges accumulated in the photoelectric conversion element 1.

The signal charges accumulated in the photoelectric conversion element 1 are transferred from the photoelectric conversion element 1 to the read gates φ1, φ3, φ5, φ7 of the vertical transfer section 2 in the direction indicated by the arrow a in FIG. Next, the signal charges are transferred from the vertical transfer unit 2 to the horizontal transfer unit 3 in the direction indicated by the arrow b in FIG. Horizontal transfer unit 3
2 is transferred to the output amplifier section 4 in the direction indicated by arrow c in FIG. The output amplifier unit 4 generates an output signal according to the amount of the transferred signal charges.

A conventional method for driving a solid-state image pickup device will be described below. FIG. 3 is a driving timing chart of a solid-state imaging device for reading pulses applied to four types of read gates φ1, φ3, φ5, and φ7 that read out signal charges accumulated by the photoelectric conversion element 1 of FIG. 2 to the vertical transfer unit 2 of FIG. Is. In FIG. 3, 5 is a first read pulse, 6 is a second read pulse, 7 is a third read pulse, and 8 is a fourth read pulse, and these are signal charges accumulated by the photoelectric conversion element 1 of FIG. Four types of read gates φ1, φ3, φ5, φ read out to the vertical transfer unit 2 of FIG.
7 in chronological order. Reference numeral 9 denotes an electronic shutter control pulse having a constant cycle which is a discharge pulse applied to the substrate.

The operation of the driving method of the solid-state image pickup device configured as described above will be described below. In the electronic shutter mode, the accumulation time from the last pulse 301 of the electronic shutter control pulse 9 to the first read pulse 5 is t
1, the accumulation time from the last pulse 301 of the electronic shutter control pulse 9 to the second read pulse 6 is t2, the accumulation time from the last pulse 301 of the electronic shutter control pulse 9 to the third read pulse 7 is t3, the electronic shutter When the accumulation time from the last pulse 301 of the control pulse 9 to the fourth read pulse 8 is t4, the signal charge accumulated at the accumulation time t1 in the photoelectric conversion element 1 of FIG. 2 is the first read pulse 5 and the accumulation time. The signal charge accumulated at t2 is the second
The read pulse 6, the signal charge accumulated at the accumulation time t3 is the third read pulse 7, and the signal charge accumulated at the accumulation time t4 is the fourth read pulse 8 at the gates φ1, φ3, φ5 of the vertical transfer unit 2 of FIG. , Φ7, respectively. The signal charge read by the first read pulse 5 and the signal charge read by the second read pulse 6 are shown in FIG.
Of the signal charges read out by the third read pulse 7 and the fourth read pulse 8
The signal charges read in step 2 are charge-coupled in the vertical transfer unit 2 of FIG. Each pair of charge-coupled signal charges is transferred from the vertical transfer unit 2 of FIG. 2 to the horizontal transfer unit 3 of FIG. 2 once in one horizontal synchronization period, and is supplied to the output amplifier unit 4 of FIG. In the output amplifier section 4 of FIG. 2, the output signal corresponding to the amount of each signal charge that is charge-coupled is converted into a voltage.

[0007]

However, in the above conventional technique, in the electronic shutter mode, the accumulation time t1 from the last pulse 301 of the electronic shutter control pulse 9 to the first read pulse 5 and the electronic shutter control pulse 9 are set. The sum of the accumulation time t2 from the last pulse 301 to the second read pulse 6, and the accumulation time t3 from the last pulse 301 to the third read pulse 7 of the electronic shutter control pulse 9 and the electronic shutter control pulse 9. Accumulation time t from the last pulse 301 to the fourth read pulse 8
The sum of the storage times of 4 is different. That is, t1 + t2 <t3 + t4. Therefore, even if the amount of light incident on each photoelectric conversion element 1 is the same, a difference occurs in the output signal levels according to the respective charge-coupled signal charges in the output amplifier section 4 of FIG. On the monitor screen,
Flicker and line crawl occur.

The present invention solves the above problems and provides a method for driving a solid-state image pickup device capable of equalizing the time integral values of the signal charges of each of the coupled n / 2 pairs or 2 pairs. The purpose is to

[0009]

According to a first aspect of the present invention, there is provided a method for driving a solid-state image pickup device, wherein signal charges read out from n photoelectric conversion elements arranged in a vertical direction by n kinds of read gates are read in a vertical direction. When two photoelectric conversion elements arranged side by side are paired and each pair of two photoelectric conversion elements are coupled and transferred in the vertical direction, the signal charges accumulated in the photoelectric conversion elements are transferred in the same field. For reading, the pulse applied to the n kinds of read gates is the i-th (i = 1, 2, 3, ... N) read-out pulse in the time sequence of reading, and among the i-th read-out pulse, the j-th (j = j = 1, 2,
3, ... N / 2) The signal charge read by the read pulse and the k-th (k = n + 1−) of the i-th read pulse
j) It is characterized in that the signal charges read by the read pulse are combined.

According to a second aspect of the present invention, there is provided a method for driving a solid-state image pickup device, wherein four types of read gates are arranged in a vertical direction.
When the signal charge read out from each photoelectric conversion element is paired with two photoelectric conversion elements arranged in the vertical direction, and each pair of two photoelectric conversion elements is coupled and transferred in the vertical direction. In order to read out the signal charges accumulated in the photoelectric conversion element in the same field, the pulses to be applied to the four kinds of read gates are read out in the order of time, that is, the first read pulse, the second read pulse, and the third read pulse. ,
The fourth read pulse is used, and the signal charge read by the first read pulse and the signal charge read by the fourth read pulse are combined, and the signal charge read by the second read pulse and the third read pulse are combined. It is characterized in that the read signal charges are combined.

According to a third aspect of the present invention, there is provided a method of driving a solid-state image pickup device according to the first or second aspect of the present invention, wherein a discharge pulse is applied to the substrate to accumulate the signal charge accumulated in the image pickup section. After being discharged through the substrate, signal charges are accumulated in the photoelectric conversion element.

[0012]

According to the structure of the first aspect, when the amount of light incident on the photoelectric conversion element is the same, when reading the signal charges accumulated in the photoelectric conversion element to the vertical transfer unit, n kinds of signals are read out. Among the signal charges read by the read gate, the time integration values of the n / 2 pairs of signal charges in which the signal charges read by the two types of read gates are combined become equal.

According to the structure described in claim 2, when the signal charges accumulated in the photoelectric conversion element are read out to the vertical transfer section when the amount of light incident on the photoelectric conversion element is the same,
Of the signal charges read by the four types of read gates, the time integration values of the two pairs of signal charges obtained by combining the signal charges read by the two types of read gates become equal.

According to the structure of claim 3, the unevenness of the image due to the non-uniform residual signal charge is eliminated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a driving timing chart of a solid-state image pickup device of a read pulse applied to a read gate in one embodiment of the present invention. 11 is a first read pulse, 12 is a second read pulse, 13 is a third read pulse, and 14 is a fourth read pulse in the order of reading the read pulses applied to the four types of read gates. Reference numeral 15 denotes an electronic shutter control pulse having a constant cycle which is a discharge pulse applied to the substrate. The first read pulse 11 is the read gate φ1 of FIG. 2, the fourth read pulse 14 is the read gate φ3 of FIG. 2, the second read pulse 12 is the read gate φ5 of FIG. 2, and the third read pulse 13 is the read gate of FIG. applied to φ7 respectively.

The structure of the solid-state image pickup device is the same as that of the conventional example. The operation of the driving method of the solid-state imaging device of this embodiment configured as described above will be described below.
First, in the electronic shutter mode, electronic shutter control pulse 1
5, the accumulation time from the last pulse 101 to the first read pulse 11 is t1, the accumulation time from the last pulse 101 to the second read pulse 12 of the electronic shutter control pulse 15 is t2, and the last time of the electronic shutter control pulse 15 is t2. The accumulation time from the pulse 101 to the third read pulse 13 is t3, and the last pulse 1 of the electronic shutter control pulse 15
The accumulation time from 01 to the fourth read pulse 14 is t4
And the first read pulse 11 and the second read pulse 1
2, third read pulse 13, and fourth read pulse 14
Set the time intervals of to equal.

In the photoelectric conversion element 1 of FIG. 2, the signal charge accumulated at the accumulation time t1 is the first read pulse 11, and the signal charge accumulated at the accumulation time t2 is the second read pulse 1.
2. The signal charge accumulated at the accumulation time t3 is the third read pulse 13, and the signal charge accumulated at the accumulation time t4 is the fourth.
The read pulse 14 is read to the read gates φ1, φ5, φ7, and φ3 of the vertical transfer unit 2 of FIG. The signal charge read by the first read pulse 11 and the signal charge read by the fourth read pulse 14 are charge-coupled in the vertical transfer unit 2 of FIG. 2, and read by the second read pulse 12. The signal charge and the signal charge read by the third read pulse 13 are charge-coupled in the vertical transfer unit 2 of FIG.

In the case of interlaced scanning, the combination of photoelectric conversion elements 1 for coupling signal charges is 1
In the first field of the frame, one photoelectric conversion element and another photoelectric conversion element adjacent to one side in the vertical direction are paired, but one photoelectric conversion element and the other side in the vertical direction in the second field. The other photoelectric conversion element adjacent to is paired.

As described above, according to this embodiment, in the electronic shutter mode, the accumulation time t1 from the last pulse 101 of the electronic shutter control pulse 15 to the first read pulse 11 and the last time of the electronic shutter control pulse 15 are set. Accumulation time t4 from the pulse 101 to the fourth read pulse 14
Accumulation time, the accumulation time t2 from the last pulse 101 of the electronic shutter control pulse 15 to the second read pulse 12, and the accumulation time t3 from the last pulse 101 of the electronic shutter control pulse 15 to the third read pulse 13.
The sum of the accumulation times of is equal. That is, t1 + t4 = t2 + t3.

In the above embodiment, the first read pulse 11, the second read pulse 12 and the third read pulse 1 are used.
Although the sum of the accumulation times t1 and t4 and the sum of the accumulation times t2 and t3 are equal on the assumption that the time intervals of the third and fourth read pulses 14 are equal, the sum of the accumulation times t1 and t4 and the sum of the accumulation times t2 and t3 are equal. So that the first read pulse 11
It is also possible to arbitrarily set the time intervals of the second read pulse 12, the third read pulse 13, and the fourth read pulse 14.

In the above embodiment, the driving method has four read gates, but n (n = 2m; m)
The present invention can also be applied to a case in which there are two or more types of read gates. In this case, in order to read out the signal charges accumulated in the photoelectric conversion element in the same field, the pulses applied to the n kinds of read gates are read in the i-th order (i = 1, 2, 3, ...
n) a read pulse, of the i-th read pulse,
Of the signal charges read by the j-th (j = 1, 2, 3, ... N / 2) read pulse and the k-th (k = n + 1−j) read pulse of the i-th read pulse. Combine signal charges.

[0022]

According to the method for driving a solid-state image pickup device of the first aspect, when the amount of light incident on the photoelectric conversion element is the same, the charge-coupled signal charges of n / 2 pairs are generated. The time integrated values can be made equal, and the levels of the respective output signals converted according to the signal charges in the output amplifier section can be made equal. Therefore, it is possible to eliminate the occurrence of flicker and line crawl on the monitor screen.

According to the driving method of the solid-state image pickup device of the second aspect, when the light amount of the light incident on the photoelectric conversion element is the same, the time-integrated value of each of the two pairs of signal charges that are charge-coupled is calculated. They can be made equal, and the levels of the respective output signals converted according to the signal charges in the output amplifier section can be made equal. Therefore, it is possible to eliminate the occurrence of flicker and line crawl on the monitor screen.

According to the solid-state imaging device driving method of the third aspect, it is possible to eliminate the unevenness of the image due to the non-uniform residual signal charge on the monitor screen.

[Brief description of drawings]

FIG. 1 is a drive timing chart of a read pulse signal according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of a solid-state imaging device.

FIG. 3 is a drive timing chart of a conventional read pulse signal.

[Explanation of symbols]

 1 photoelectric conversion element 2 vertical transfer unit 3 horizontal transfer unit 4 output amplifier unit 5 first read pulse 6 second read pulse 7 third read pulse 8 fourth read pulse 9 electronic shutter control pulse 11 first read pulse 12 second read Pulse 13 Third read pulse 14 Fourth read pulse 15 Electronic shutter control pulse 101 Last pulse of electronic shutter control pulse 301 Last pulse of electronic shutter control pulse 9

Claims (3)

[Claims] 1. A plurality of two-dimensionally arranged photoelectric conversion elements, n (n = 2 m; m is a natural number of 2 or more) read gates for reading signal charges accumulated in the photoelectric conversion elements, and n kinds of read gates. 2 photoelectric conversion elements forming a pair, each pair consisting of two photoelectric conversion elements arranged in the vertical direction of the signal charges read from n photoelectric conversion elements arranged in the vertical direction by the read gate Depending on the amount of the signal charge transferred by the horizontal transfer unit, a vertical transfer unit that transfers the signal charges transferred by the vertical transfer unit in the horizontal direction, and a horizontal transfer unit that transfers the signal charges transferred by the vertical transfer unit in the horizontal direction. A driving method for a solid-state imaging device, comprising: an output amplifier section for generating an output signal, wherein signal charges accumulated in the photoelectric conversion element are applied to n kinds of read gates in order to read the signal charges in the same field. You A pulse, in time order to read the i (i =
1, 2, 3, ..., N) read pulses, and among the i-th read pulse, the j-th (j = 1, 2, 3, ... N / 2)
Driving a solid-state imaging device, characterized in that the signal charge read by a read pulse and the signal charge read by a kth (k = n + 1-j) th read pulse of the i-th read pulse are combined. Method. 2. A plurality of two-dimensionally arranged photoelectric conversion elements, four kinds of read gates for reading out signal charges accumulated in the photoelectric conversion elements, and four pieces arranged in a vertical direction by the four kinds of read gates. Vertical transfer in which the signal charges read out from the photoelectric conversion element are paired with two photoelectric conversion elements arranged in the vertical direction, and the two photoelectric conversion elements forming each pair are combined and transferred in the vertical direction. Unit, a horizontal transfer unit that horizontally transfers the signal charges transferred by the vertical transfer unit, and an output amplifier unit that generates an output signal according to the amount of the signal charges transferred by the horizontal transfer unit. A driving method of a solid-state imaging device, wherein in order to read out signal charges accumulated in the photoelectric conversion element in the same field, four types of pulses applied to the read gates are read in a temporal order of reading. A read pulse, a second read pulse, a third read pulse, and a fourth read pulse are set, and the signal charge read by the first read pulse and the signal charge read by the fourth read pulse are combined, A method of driving a solid-state imaging device, characterized in that the signal charges read by two read pulses and the signal charges read by the third read pulse are combined. 3. The solid-state image pickup device according to claim 1, wherein a discharge pulse is applied to the substrate to discharge the signal charge accumulated in the image pickup section through the substrate, and then the signal charge is accumulated in the photoelectric conversion element. Driving method.