JP2997974B2 - 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 and movies using a solid-state imaging device (CCD) have become widespread, and demand for high added value has increased. There is a demand for driving with the above-mentioned driving timing.

[0003] When driving is performed according to the drive timing of the solid-state image pickup device, all processing must be performed within a blanking period of a television signal, and there is a time limitation. As a driving method using a solid-state imaging device, after reading charges from the photodiode to the vertical transfer unit, an arbitrary number of stages are transferred at high speed in the direction of the horizontal transfer unit on the vertical transfer unit within the vertical blanking period, and the horizontal transfer unit is used. In some cases, unnecessary charges may be discharged via the signal charge detection unit.

FIG. 5 shows a drive timing chart of the solid-state image pickup device. The solid-state image pickup device is an interline type CCD having a structure of four vertical phases, two horizontal phases, and a structure in which charges are read out from photodiodes φV1, 3 gates. FIG. 5 shows four phases (φV1 to φV4) of the vertical transfer unit and two phases (φH1, φH1) of the horizontal transfer unit during the vertical blanking period of the television signal.
2), blanking signal (BLK), vertical synchronization signal (VD),
The horizontal synchronizing signal (HD) is shown.

First, a pulse having a voltage of about 15 V is applied to the φV1,3 gates to transfer the charges accumulated in the photodiodes to the vertical transfer unit. The upper and lower pairs are changed and mixed on the vertical transfer unit. Next, after charge mixing, an arbitrary number of stages are transferred at high speed on the vertical transfer unit by the vertical high-speed transfer unit A of a certain vertical transfer unit, and several stages of unnecessary charges on the vertical transfer unit are discharged. During the period, the vertical transfer unit is stopped, and after the unnecessary charges remaining on the horizontal transfer unit have been discharged, normal vertical transfer starts from point B.

In general, when a high-luminance subject is imaged by a camera using a solid-state imaging device, the amount of accumulated smear component generated in a vertical transfer unit corresponding to the high-luminance part is calculated by integrating the amount of smear component during the transfer stop period of the vertical transfer unit. Amount. The suspension period is the suspension period of the vertical transfer unit during normal transfer (about one horizontal scanning period)
If the length is longer than this, at the start of the normal vertical transfer, the amount of smear becomes larger than a normal smear amount, becomes a bright point (hereinafter, referred to as a smear bright point), and stands out like a white flaw on a monitor.

That is, when the vertical high-speed transfer frequency in the vertical high-speed transfer A section in FIG. 5 is constant and the number of vertical high-speed transfer stages is changed, the level of the smear luminescent spot also changes according to the number of vertical high-speed transfer stages. .

For example, when the number of vertical high-speed transfer stages is large, the transfer stop time from the end of vertical high-speed transfer to normal vertical transfer is shortened, and the level of smear bright spots is reduced. The transfer stop time from the end of the high-speed transfer to the normal vertical transfer becomes longer, and the level of the smear bright spot becomes larger.

[0009]

As described above, even if the same object is photographed on the monitor, the amount of accumulation of the smear component due to the change in the number of vertical high-speed transfer stages on the vertical transfer unit after the charge readout is changed. There is a problem that the level of the smear luminescent spot changes and the human eye reacts sensitively to this.

The present invention solves the above-mentioned problems, and reduces the change in the transfer stop period of the vertical transfer section from the end of vertical high-speed transfer to the normal transfer after reading out the signal charge to the vertical transfer section, or reduces this transfer stop. An object of the present invention is to make it possible to reduce the smear bright spot level by shortening the period.

[0011]

The present invention SUMMARY OF] In order to solve the above problems, the invention according to a first aspect of the present invention, a matrix
A plurality of photoelectric conversion elements arranged in a vertical transfer section for transferring in the vertical direction is read out the signal charges accumulated in the photoelectric conversion element <br/>, the signal charges transferred from said vertical transfer unit It includes a horizontal transfer section for transferring in the horizontal direction, and a signal charge detection unit for converting the signal charge from the horizontal transfer unit into a signal voltage or signal current, before the first time
Reading signal charges from the photoelectric conversion element to the vertical transfer unit
After that, unnecessary charges of n stages are transferred from the vertical transfer section to the horizontal transfer section.
Transfer and eject at a first high speed transfer frequency, and then
The horizontal synchronization signal from the vertical transfer unit to the horizontal transfer unit at the time
A method for driving a solid-state imaging device that performs normal transfer in synchronization with the first time and the second time that is F between the first time and the second time.
Of the vertical transfer unit that can perform high-speed transfer at a high-speed transfer frequency of
Assuming that the maximum number of transfer stages is N, the N is set to 1 or more.
The first high-speed transfer each time the smaller value of n changes
The frequency is controlled so as to be F × (n / N), and the unnecessary
It discharges electric charges .

[0012] The invention of claim 2, wherein the present invention, the line
A plurality of photoelectric conversion elements arranged in a row, and the photoelectric conversion
Reads out the signal charge stored in the device and transfers it vertically
A vertical transfer unit that transfers data from the vertical transfer unit.
A horizontal transfer unit for transferring a signal charge in a horizontal direction;
The signal charge from the transfer unit is converted into a signal voltage or a signal current.
A signal charge detection unit that converts and outputs the signal charge,
Read signal charges from the photoelectric conversion element to the vertical transfer unit.
After the transfer, the horizontal transfer from the vertical transfer unit is performed at the second time.
Until the normal transfer synchronized with the horizontal synchronization signal to the unit starts
A third time provided between the first time
At a second high-speed transfer frequency F between
The maximum transfer number of the vertical transfer units that can perform high-speed transfer is
When N is set, there is no need for n or more stages that are smaller than the N stages.
The charge is transferred from the vertical transfer section to the horizontal transfer section at the high speed.
The third time at which the transfer is started at the transmission frequency and the discharge is started,
(N−n) from the time when the high-speed transfer of the N stages is started.
/ F is delayed.

Further, the invention according to claim 3 of the present invention, the line
A plurality of photoelectric conversion elements arranged in a row, and the photoelectric conversion
A horizontal transfer section for transferring the vertical transfer section for transferring in the vertical direction is read out the signal charges accumulated in the element, the <br/> signal charges transferred from said vertical transfer unit in a horizontal direction, said horizontal transfer unit said signal charges and outputs the converted into a signal voltage or signal current signal charge detector from, free of m rows the is in the horizontal transfer portion means for reading out from the signal charges the photoelectric conversion element of the vertical transfer portion and a pseudo transfer portion reads a signal charge from the photoelectric conversion element to the vertical transfer section
The unnecessary charges in the n stages of the vertical transfer unit
After the transfer from the printer to the horizontal transfer unit at a high transfer frequency and ejection
The horizontal transfer from the vertical transfer unit to the horizontal transfer unit.
Until the normal transfer synchronized with the synchronization signal starts, 1
The vertical transfer unit is horizontally moved by the number of stages not less than m and not more than m stages.
Normal transfer is performed so as to synchronize with the synchronization signal .

[0014]

According to the first aspect of the present invention, by controlling the transfer frequency of the vertical high-speed transfer section A after charge reading in accordance with the number of transfer stages, the time from the end of the vertical high-speed transfer to the normal vertical transfer is controlled. Becomes almost constant, the level change of the smear luminescent spot when the number of transfer stages is changed can be reduced more than the fixed time when the transfer frequency of the vertical high-speed transfer A section is constant, and the absolute level of the smear luminescent spot is further reduced. It is also possible.

According to the second aspect of the invention, by controlling the start position of the vertical high-speed transfer after the charge readout according to the number of transfer stages, the time from the end of the vertical high-speed transfer to the normal vertical transfer becomes constant, and the transfer is completed. It is possible to completely eliminate the level change of the smear luminescent spot when the number of steps is changed, and it is also possible to lower the absolute level of the smear luminescent spot.

According to the third aspect of the present invention, the absolute level of smear luminescent spots can be reduced by shortening the vertical transfer section stop period when unnecessary charges are discharged from the horizontal transfer section after charge reading and vertical high-speed transfer. It is.

[0017]

FIG. 1 shows a drive timing chart of an embodiment according to the first aspect of the present invention, and is a detailed timing chart of .phi.V1 to .phi.V4 of the vertical high-speed transfer A section in FIG.

In this embodiment, as shown in FIG. 5, an arbitrary number of stages are transferred at high speed on the vertical transfer unit by the vertical high-speed transfer unit A after charge mixing, and unnecessary charges on the vertical transfer unit are transferred to the horizontal transfer unit. After the transfer, the vertical transfer unit is stopped for several horizontal scanning periods, unnecessary charges of the horizontal transfer unit are discharged, and normal vertical transfer starts from point B. Here, the charges accumulated in the photodiode are transferred to the vertical transfer unit. And a maximum of N transfer stages during a T period (see FIG. 5) from a point immediately after the charges of the two photodiodes are mixed on the vertical transfer unit to a point B at which normal vertical transfer starts. When the frequency is F, the desired number of transfer stages is n ( n can be in the range of 0 <n <N).
Vertical high speed transfer frequency for transferring variable) F × (n /
N) is controlled every time the value of n changes.

That is, as shown in the detailed timing chart of the N-stage vertical high-speed transfer section in FIG. 1, in the case of FIG. 1 (1) in which N-stage vertical high-speed transfer is performed, the signal charges are transferred for one scanning line toward the horizontal transfer section. Although the transfer time is 1 / F, when performing N / 2-stage vertical high-speed transfer, the signal charges are horizontally transferred as shown in the detailed timing diagram of the N / 2-stage vertical high-speed transfer unit in FIG. The maximum transfer time for one scanning line in the direction of the section is 2 / F.

FIG. 2 is a drive timing chart of an embodiment according to the second aspect of the present invention, and is a detailed timing chart of φV1 to φV4 of the vertical high-speed transfer A section in FIG.

In this embodiment, as shown in FIG. 2A, the start position of the vertical high-speed transfer for transferring the desired number of transfer stages n (n ≦ N) is determined by transferring signal charges from the photodiode to the vertical transfer unit. The S point is controlled every time the value of n changes so as to start from the S point delayed by (N−n) / F from the position where the N-stage vertical high-speed transfer is started immediately after the start.

That is, as shown in FIG. 2B, when the vertical high-speed transfer of N-4 stages is performed with respect to the vertical high-speed transfer start position of the N-stage vertical high-speed transfer, the vertical high-speed transfer start position is determined. Is S point delayed by 4 / F as compared with the time when the N-stage vertical high-speed transfer is performed.

FIGS. 3 and 4 show a drive timing chart of an embodiment according to the third aspect of the present invention.

The solid-state image pickup device is an interline CCD having a structure in which charges are read out from the four-phase, two-phase, and photodiodes from the φV1 and 3 gates. A pseudo transfer unit (hereinafter, referred to as a dummy bit) not connected to the photoelectric conversion unit (2 rows).
It has.

FIG. 3 shows four phases of the vertical transfer section (φV1 to φV4), two phases of the horizontal transfer section (φH1 and φH2), a blanking signal (BLK), and vertical synchronization during the vertical blanking period of the television signal. 5 shows a signal (VD) and a horizontal synchronizing signal (HD).

FIG. 4 shows the vertical transfer B and C shown in FIG.
FIG. 6 is a detailed timing chart of points φV1 to φV4.

First, a pulse having a voltage of about 15 V is applied to the φV1,3 gates to transfer the charges accumulated in the photodiodes to the vertical transfer unit. In order to perform interlacing, the charges of the two photodiodes are transferred by the field. The upper and lower pairs are changed and mixed on the vertical transfer unit.

After charge mixing, an arbitrary number of stages are transferred at high speed on the vertical transfer unit by the vertical high-speed transfer unit A of a certain vertical transfer unit, and unnecessary charges on the vertical transfer unit are discharged. The vertical transfer unit is stopped, and unnecessary charge discharge of the horizontal transfer unit is started. Thereafter, the normal transfer of the vertical transfer unit is started while the horizontal transfer unit is operating ( point C ). From the point C, the vertical transfer unit is operated by the number of rows equal to or less than the number of dummy bit lines, that is, L rows (here, L = 2 ) before the horizontal scanning period ( point B ), and unnecessary charges of the horizontal transfer unit are operated. After the ejection is completed, normal vertical transfer is started from point B.

In the above embodiment, the vertical high-speed transfer frequency for transferring the desired number of transfer stages n and the start position S of the vertical high-speed transfer in claim 2 are determined in the vertical blanking period. Any time before the signal charge is transferred from the photodiode to the vertical transfer unit within the above.

As described above, by changing the drive timing, it is possible to improve the smear luminescent spot without impairing the functions of the solid-state image sensor such as the electronic zoom.

[0031]

As described above, the solid-state imaging device of the present invention
According to the driving method of the device, in the invention according to the first aspect, the transfer frequency of the vertical high-speed transfer A portion after the charge readout is controlled according to the number of transfer stages, from the end of the vertical high-speed transfer to the normal vertical transfer. Time becomes almost constant, the level change of the smear luminescent spot when the number of transfer stages is changed can be lessened than the time when the transfer frequency of the vertical high-speed transfer section A is constant, and the absolute level of the smear luminescent spot can be further reduced. Can also be reduced.

According to the second aspect of the present invention, by controlling the start position of the vertical high-speed transfer section A after the charge readout in accordance with the number of transfer stages, the time from the end of the vertical high-speed transfer to the normal vertical transfer is kept constant. That is, it is possible to completely eliminate the level change of the smear luminescent spot when the number of transfer stages is changed, and it is also possible to lower the absolute level of the smear luminescent spot.

According to the third aspect of the present invention, charge reading,
After the vertical high-speed transfer, the absolute level of smear luminescent spots can be reduced by shortening the vertical transfer unit stop period when unnecessary charges are discharged from the horizontal transfer unit.

[Brief description of the drawings]

FIG. 1 is a drive timing chart of a solid-state imaging device according to an embodiment of the present invention.

FIG. 2 is a drive timing chart of a solid-state imaging device according to an embodiment of the invention described in claim 2;

FIG. 3 is a drive timing chart of a solid-state imaging device according to an embodiment of the invention described in claim 3;

FIG. 4 is a partially enlarged view of the driving timing of FIG. 3;

FIG. 5 is a drive timing diagram of a conventional solid-state imaging device.

[Explanation of symbols]

A: vertical high-speed transfer unit, F: N-stage vertical high-speed transfer frequency,
B: Normal vertical transfer start point after charge reading, S:
n-stage vertical high-speed transfer start point, T: time from charge mixing until normal vertical transfer starts, C: dummy bit transfer start point.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/30-5/335

Claims (3)

(57) [Claims] 1. A plurality of photoelectric conversion elements arranged in a matrix
When read the signal charge accumulated in the photoelectric conversion element
Conversion and vertical transfer section for transferring in the vertical direction, a horizontal transfer section for transferring the signal charges transferred from said vertical transfer unit in a horizontal direction, the signal charge from the horizontal transfer unit into a signal voltage or signal current Te A signal charge detecting unit for outputting the vertical transfer from the photoelectric conversion element at a first time.
After reading the signal charge to
Transfer from the sending unit to the horizontal transfer unit at the first high-speed transfer frequency
Discharge, and then at a second time from the vertical transfer
A method for driving a solid-state imaging device that performs normal transfer to a transfer unit in synchronization with a horizontal synchronization signal , wherein a second high-speed F between the first time and the second time is set.
Of the vertical transfer units that can perform high-speed transfer at the transfer frequency,
Assuming that the maximum number of transfer stages is N stages, it is 1 or more and smaller than N.
Each time the value of n changes, the first high-speed transfer frequency
Is controlled to be F × (n / N) by controlling the unnecessary charge.
A driving method of a solid-state imaging device , wherein the driving is performed . 2. A plurality of photoelectric conversion elements arranged in a matrix.
When read the signal charge accumulated in the photoelectric conversion element
Conversion and vertical transfer section for transferring in the vertical direction, a horizontal transfer section for transferring the signal charges transferred from said vertical transfer unit in a horizontal direction, the signal charge from the horizontal transfer unit into a signal voltage or signal current Te and a signal charge detection unit that is output, signal from said photoelectric conversion elements in the first time to the vertical transfer section
After reading the signal charge, the second transfer is performed at the second time.
Normal transfer synchronized with the horizontal sync signal to the horizontal transfer
A third time provided before the start,
A second high-speed transfer F between the first time and the second time
Transfer of the vertical transfer unit capable of high-speed transfer at a frequency
If the maximum number of stages is N, one or more stages are smaller than the N stages.
Transfer unnecessary charge of n stages from the vertical transfer unit to the horizontal transfer unit.
Transfer at the high-speed transfer frequency to start discharging
3 is the time when the high-speed transfer of the N stages is started.
Remote (N-n) / F solid state imaging instrumentation, characterized in that the delay
The driving method of location. 3. A plurality of photoelectric conversion elements arranged in a matrix.
When read the signal charge accumulated in the photoelectric conversion element
Conversion and vertical transfer section for transferring in the vertical direction, a horizontal transfer section for transferring the signal charges transferred from said vertical transfer unit in a horizontal direction, the signal charge from the horizontal transfer unit into a signal voltage or signal current Te A signal charge detection unit for outputting
The photoelectric conversion unit is located on the side of the horizontal transfer unit of the vertical transfer unit.
And a pseudo transfer portion of m rows no means for reading out signal charges from the device, to read a signal charge from the photoelectric conversion element to the vertical transfer section
Out of the vertical transfer section, and vertically transfer unnecessary charges in n stages.
Transfer from the sending unit to the horizontal transfer unit at high transfer frequency and discharge
After the transfer from the vertical transfer unit to the horizontal transfer unit.
Until the normal transfer synchronized with the horizontal sync signal is started
The vertical transfer unit includes at least one stage and at most m stages.
A method for driving a solid-state imaging device , wherein normal transfer is performed so as to be synchronized with a horizontal synchronization signal .