JP3345182B2 - Driving method of solid-state imaging device - Google Patents

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 imaging device.

[0002]

2. Description of the Related Art At present, cameras using CCDs have become widespread, and CCDs capable of realizing high resolution and high functions have been demanded. 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 denotes a plurality of two-dimensionally arranged photoelectric conversion elements. Numeral 2 denotes two sets of vertically arranged signal charges read out from four photoelectric conversion elements 1 arranged in the vertical direction by four types of read gates for reading out signal charges accumulated in the photoelectric conversion elements 1. A vertical transfer unit that combines the conversion elements 1 and couples each pair of the two photoelectric conversion elements 1 to transfer in the vertical direction. Reference numeral 3 denotes a horizontal transfer unit that transfers the signal charges transferred by the vertical transfer unit 1 in the horizontal direction. Reference numeral 4 denotes an output amplifier that generates an output signal corresponding to the amount of signal charge transferred by the horizontal transfer unit 3.

[0003] 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 vertical transfer gate is defined as φ1, φ2, φ3,
Expressed by φ4, φ5, φ6, φ7, φ8. Of these vertical transfer gates φ1 to φ8, φ1, φ3, φ5, and φ7 also serve as readout gates for reading out signal charges accumulated in the photoelectric conversion element 1.

The signal charges stored 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, 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
Are transferred to the output amplifier unit 4 in the direction indicated by the arrow c in FIG. The output amplifier unit 4 generates an output signal according to the amount of the transferred signal charge.

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

[0006] The operation of the driving method of the solid-state imaging 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 represented by 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, Assuming that the accumulation time from the last pulse 301 of the control pulse 9 to the fourth read pulse 8 is t4, the signal charges accumulated in the photoelectric conversion element 1 in the accumulation time t1 in FIG. The signal charge accumulated at t2 is the second
The read pulse 6, the signal charge accumulated during the accumulation time t3 is the third read pulse 7, and the signal charge accumulated during the accumulation time t4 is converted into the gates φ1, φ3, φ5 of the vertical transfer unit 2 in FIG. , Φ7. The signal charges read by the first read pulse 5 and the signal charges read by the second read pulse 6 are shown in FIG.
The signal charges read out by the third readout pulse 7 and the fourth readout pulse 8
The signal charges read out in step (1) are charge-coupled in the vertical transfer unit 2 in 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 supplied to the output amplifier unit 4 of FIG. An output signal corresponding to the amount of each signal charge that has been charge-coupled by the output amplifier unit 4 in FIG. 2 is converted into a voltage.

[0007]

However, in the above-mentioned 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 accumulation time t1 of the electronic shutter control pulse 9 are reduced. The sum of the accumulation time of the accumulation time t2 from the last pulse 301 to the second read pulse 6, the accumulation time t3 from the last pulse 301 of the electronic shutter control pulse 9 to the third read pulse 7, and the accumulation time t3 of the electronic shutter control pulse 9 Storage time t from last pulse 301 to fourth read pulse 8
4 have different sums of accumulation times. That is, t1 + t2 <t3 + t4. For this reason, even if the amount of light incident on each photoelectric conversion element 1 is the same, a difference occurs in the level of the output signal corresponding to each charge-coupled signal charge in the output amplifier unit 4 of FIG. On the monitor screen.
Flicker and line crawl occur.

The present invention solves the above-mentioned problems, and provides a driving method of a solid-state imaging device capable of equalizing the time integrals of n / 2 pairs or two pairs of signal charges combined. The purpose is to:

[0009]

According to a first aspect of the present invention, there is provided a driving method of a solid-state imaging device, wherein signal charges read from n photoelectric conversion elements arranged vertically by n kinds of read gates are vertically transferred. When the two photoelectric conversion elements arranged side by side are paired and each pair of two photoelectric conversion elements is combined and transferred in the vertical direction, the signal charges accumulated by the photoelectric conversion elements are transferred in the same field. In order to read, the pulses applied to the n kinds of read gates are set as the i-th (i = 1, 2, 3,..., N) read pulses in the read temporal order, and the j-th (j = j) 1,2,
3,... N / 2) of the signal charges read out by the readout pulse and the k-th (k = n + 1−) of the i-th readout pulse.
j) combining signal charges read by a read pulse.

According to a second aspect of the present invention, there is provided a method for driving a solid-state imaging device, comprising:
When transferring the signal charges read from the two photoelectric conversion elements in the vertical direction by combining each of the two photoelectric conversion elements arranged in the vertical direction as a pair and combining each of the two photoelectric conversion elements in each pair In order to read out the signal charges accumulated in the photoelectric conversion element in the same field, the first read pulse, the second read pulse, and the third read pulse are sequentially applied to the four types of read gates in the read time sequence. ,
The fourth read pulse is combined with the signal charge read by the first read pulse and the signal charge read by the fourth read pulse, and the signal charge read by the second read pulse and the third read pulse are combined. The read signal charges are combined.

According to a third aspect of the present invention, there is provided a driving method of a solid-state imaging device according to the first or second aspect, wherein an ejection pulse is applied to a substrate, and a signal charge stored in an imaging section is applied. Is discharged through the substrate, and then the signal charges are accumulated in the photoelectric conversion element.

[0012]

According to the first aspect of the present invention, when the amount of light incident on the photoelectric conversion element is the same, when reading out the signal charges accumulated in the photoelectric conversion element to the vertical transfer unit, n types of signals are read. Of the signal charges read by the read gate, the time integral of n / 2 pairs of signal charges obtained by combining the signal charges read by the two types of read gates becomes equal.

According to the second aspect of the present invention, when the amount of light incident on the photoelectric conversion element is the same, when reading out the signal charges accumulated in the photoelectric conversion element to the vertical transfer section,
Of the signal charges read by the four kinds of read gates, the time integrals of two pairs of signal charges obtained by combining the signal charges read by the two kinds of read gates become equal.

According to the third aspect of the present invention, unevenness of an image due to non-uniform residual signal charges is eliminated.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a solid-state imaging device driving timing chart of a read pulse applied to a read gate according to an embodiment of the present invention. Reference numeral 11 denotes a first read pulse, reference numeral 12 denotes a second read pulse, reference numeral 13 denotes a third read pulse, and reference numeral 14 denotes a fourth read pulse. Reference numeral 15 denotes an electronic shutter control pulse having a constant period, which is a bare 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.

The configuration of the solid-state imaging device is the same as that of the conventional example. The operation of the driving method of the solid-state imaging device according to this embodiment configured as described above will be described below.
First, in the electronic shutter mode, the electronic shutter control pulse 1
5, the accumulation time from the last pulse 101 to the first readout pulse 11 is t1, the accumulation time from the last pulse 101 of the electronic shutter control pulse 15 to the second readout pulse 12 is t2, and the last time of the electronic shutter control pulse 15 is 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
2nd, 3rd readout pulse 13 and 4th readout pulse 14
Set the time intervals of.

The signal charge stored in the photoelectric conversion element 1 in FIG. 2 during the storage time t1 is the first read pulse 11, and the signal charge stored in the storage 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 read pulse.
The data is read to the read gates φ1, φ5, φ7, and φ3 of the vertical transfer unit 2 in FIG. The signal charges read by the first read pulse 11 and the signal charges read by the fourth read pulse 14 are charge-coupled in the vertical transfer unit 2 in 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 in FIG.

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

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 Storage time t4 from pulse 101 to fourth read pulse 14
, 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.
Are 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
The sum of the accumulation times t1 and t4 and the sum of the accumulation times t2 and t3 are equal, assuming that the time intervals of the third and fourth readout pulses 14 are equal, but 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 interval between 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 types of read gates, but n (n = 2 m; m
The present invention can be applied to a case where two or more natural numbers) of read gates are provided. In this case, in order to read out the signal charges accumulated in the photoelectric conversion elements in the same field, the pulses applied to the n kinds of readout gates are sequentially read out in the ith (i = 1, 2, 3,.
n) A read pulse, and among the i-th read pulses,
The signal charge 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 driving method of the solid-state imaging device according to the first aspect, when the amount of light incident on the photoelectric conversion element is the same, each of the n / 2 pairs of charge-coupled signal charges is output. The time integration value can be made equal, and the level of each output signal converted according to the signal charge in the output amplifier can be made equal. Therefore, the occurrence of flicker and line crawl on the monitor screen can be eliminated.

According to the driving method of the solid-state imaging device according to the second aspect, when the amount of light incident on the photoelectric conversion element is the same, the time integration value of each of the two pairs of signal charges that are charge-coupled is calculated. The level of each output signal converted according to the signal charge in the output amplifier unit can be made equal. Therefore, the occurrence of flicker and line crawl on the monitor screen can be eliminated.

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

[Brief description of the drawings]

FIG. 1 is a drive timing chart of a read pulse signal in one embodiment of the present invention.

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

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoelectric conversion element 2 vertical transfer section 3 horizontal transfer section 4 output amplifier section 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 15 301 Last pulse of electronic shutter control pulse 9

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/335 H01L 27/146

Claims (3)

(57) [Claims] 1. A plurality of two-dimensionally arranged photoelectric conversion elements, n (n = 2m; m is a natural number of 2 or more) kinds of read gates for reading signal charges accumulated in the photoelectric conversion elements, and n kinds of read gates The signal read out from the n photoelectric conversion elements arranged in the vertical direction by the readout gate is a pair of two photoelectric conversion elements arranged in the vertical direction. A vertical transfer unit that transfers the signal charges transferred in the vertical transfer unit in the horizontal direction, and a horizontal transfer unit that transfers the signal charges transferred in the vertical transfer unit in the horizontal direction. A drive circuit for driving the solid-state imaging device, comprising: an output amplifier for generating an output signal; applying a signal charge accumulated in the photoelectric conversion element to the n types of read gates in order to read the signal charge in the same field. You A pulse, in time order to read the i (i =
.., N) read pulses and j-th (j = 1, 2, 3,..., N / 2) of the i-th read pulses
The solid-state imaging device according to claim 1, wherein the signal charge read by the read pulse and the signal charge read by the k-th (k = n + 1-j) read pulse of the i-th read pulse are combined. Method. 2. A plurality of two-dimensionally arranged photoelectric conversion elements, four types of read gates for reading signal charges accumulated in the photoelectric conversion elements, and four types of four read gates arranged in the vertical direction. Vertical transfer in which signal charges read from the photoelectric conversion elements are vertically paired and each pair of two photoelectric conversion elements arranged in the vertical direction is combined and transferred in the vertical direction. A horizontal transfer unit that transfers the signal charges transferred by the vertical transfer unit in the horizontal direction; 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 method for driving a solid-state imaging device, comprising: reading out four types of pulses applied to the readout gates in a temporal order in order to read out signal charges accumulated in the photoelectric conversion elements in the same field; A read pulse, a second read pulse, a third read pulse, and a fourth read pulse, and combining the signal charge read by the first read pulse and the signal charge read by the fourth read pulse; A method for driving a solid-state imaging device, comprising: combining signal charges read by two read pulses with signal charges read by the third read pulse. 3. The solid-state imaging device according to claim 1, wherein a signal pulse is applied to the substrate to discharge the signal charges stored in the imaging unit through the substrate, and then store the signal charges in the photoelectric conversion element. Drive method.