JPH0374979A - Sensitivity adjustment method for solid-state image pickup device - Google Patents

Abstract

PURPOSE:To obtain a consecutive natural video image by sweeping out a signal charge to a semiconductor substrate for plural number of times in a picture and transferring the signal charge to a vertical transfer section of an image pickup section for plural number of times. CONSTITUTION:A signal charge stored in a photoelectric conversion section 31 is swept out in a semiconductor substrate by using a sweepout (PHIVSUB) pulse for each horizontal blanking period after the end of the vertical blanking period and the PHIVSUB pulse is stopped at nearly the center of the picture, and a signal charge for 8 horizontal scanning periods stored in the photoelectric conversion section 31 is transferred to a vertical transfer section 32 by using a charge pulse from the center. Then the signal charge is again swept out in the semiconductor substrate from the photoelectric conversion section 31 by using the PHIVSUB pulse and the PHIVSUB pulse is stopped near the vertical blanking period, and the signal charge by the 8 horizontal scanning period from the photoelectric conversion section 31 to the vertical transfer section 32 again by using the charge pulse after the 8 horizontal scanning period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for adjusting the sensitivity of a solid-state imaging device.

2. Description of the Related Art Conventionally, an electronic shutter in a solid-state imaging device is driven by applying a pulse voltage to a substrate voltage to variably adjust the charge accumulation time to an arbitrary time.

FIG. 2 shows an example of the configuration of a conventional solid-state image sensor.

The solid-state image sensor includes a photoelectric conversion section 31, a vertical transfer section 32, an accumulation section 33, a horizontal transfer section 34, and a signal charge detection section 35. The arrow indicates the direction of normal signal charge transfer.

FIG. 3 shows an example of a composite blanking signal of a television signal and a typical drive pulse of a solid-state image sensor.

In Figure 2, (a) is a composite blanking signal, (b)
(F) is the transfer pulse (hereinafter referred to as ΦVAI pulse) applied to the VAI gate among the four-phase clocks of the vertical transfer section 32, and (C) is the VB of the four-phase clocks of the storage section 33.
(d) is one transfer pulse (hereinafter referred to as horizontal transfer pulse) of the two-phase clock that transfers the signal charge of the horizontal transfer section 34 to the signal charge detection section 35. ), (e) (g)
is a pulse (hereinafter referred to as ΦVSUB pulse) that sweeps out the signal charge accumulated in the photoelectric conversion unit 31 to the semiconductor substrate.
It shows.

Below, with reference to Figures 2 and 3, 1/1000
The operation of shifting the shutter speed from the second electronic shutter to the 1/250 second electronic shutter will be explained. First, 1000
To explain the operation for one minute of a second, the vertical blanking period D2
After each horizontal blanking interval; this ΦVSUB pulse (
e), the signal charge accumulated in the photoelectric conversion unit 31 is swept out into the semiconductor substrate, and the charge readout pulse (hereinafter abbreviated as charge pulse) is generated by ΦVSUB 16 horizontal scanning periods before C2.
The pulse (e) is stopped and accumulation of signal charges is started. After charge accumulation for 16 horizontal scanning periods, the signal charge of the photoelectric conversion section 31 is transferred to the vertical transfer section 32 by a charge pulse C2. Immediately after that, vertical high-speed transfer pulse B2 causes vertical transfer section 3 of the imaging section to
The signal charges are transferred from the storage unit 2 to the storage unit 33. Thereafter, signal charges are transferred from the storage section 33 to the horizontal transfer section 34 by the storage section vertical transfer pulse (C) every -horizontal scanning period. At the same time, a horizontal transfer pulse (d) having a frequency that can transfer one signal charge on the horizontal transfer section 34 is applied to the horizontal transfer section 34 between the accumulation section vertical transfer pulses (C), and the signal charge is detected. It is output from the section 35. The output signal of the solid-state imaging device using the above driving method is electrically processed, and 1000
Obtain a composite video signal of 1/2 second electronic shutter.

When the amount of light on the object is reduced to one-fourth, the output signal of the solid-state image sensor is reduced to one-fourth, and electrical processing is performed accordingly. Here, 1/4 of the current electronic shutter speed
Consider the case where the speed changes to 1/250th of a second.

In this case, with the electronic shutter of 1/1000 seconds, the storage time is 16 horizontal scanning periods before the charge pulse C2, but at 1/250 second, it becomes 63 horizontal scanning periods before the charge pulse C2. (FIGS. 3(f) and (g)) As described above, the speed of the electronic shutter can be changed and the sensitivity can be adjusted simply by changing the timing of the ΦVSUB pulse.

Problems to be Solved by the Invention However, with the above configuration, when a moving object is imaged, only a period corresponding to the electronic shutter speed near the vertical retrace period is sampled as an image, and the output image becomes an intermittent image. , the human eye (this is unnatural).

In view of the above-mentioned drawbacks, the present invention provides a method for adjusting the sensitivity of a solid-state imaging device, which allows continuous and clear images to be obtained when a moving object is imaged by driving the solid-state imaging device.

Means for Solving the Problems In order to solve the above problems, the sensitivity adjustment method of a solid-state imaging device according to the present invention includes sweeping signal charges to a semiconductor substrate multiple times within one screen or multiple screens, and sweeping signal charges multiple times to a semiconductor substrate. It has a configuration for transferring signal charges to the vertical transfer section of the imaging section.

Effect With this configuration, when a moving object is imaged while the total amount of charge accumulation remains the same, a more continuous and natural image can be obtained by shortening the sampling time and increasing the number of samplings.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a composite blanking signal and a drive pulse for a solid-state image sensor in this embodiment. In Figure 1, (
(a) is the composite blanking signal, (b) (f) is the imaging unit vertical transfer pulse ΦV A 1 , (C) is the storage unit vertical transfer pulse ΦV B 1 , (d) is the horizontal transfer pulse, (e)
(g) shows the ΦVSUB pulse.

Below, 1/250th from 1/1000 second electronic shutter
The operation of shifting the shutter speed to the second electronic shutter will be explained. First, to explain the 1/1000th second electronic shutter, after the end of the vertical blanking period D1, during each horizontal blanking period, the ΦVSUB pulse (e) causes the photoelectric conversion unit 31 to
Sweeps out the signal charge accumulated in the semiconductor substrate, stops the ΦVSUB pulse at approximately the center of the screen, and after 8 horizontal scanning periods from there, the photoelectric conversion unit 3 is activated by the charge pulse C1.
The signal charges for 8 horizontal scanning periods accumulated in 1 are transferred to the vertical transfer section. Thereafter, the signal charge is swept out from the photoelectric conversion unit 31 into the semiconductor substrate again by the ΦVSUB pulse, and when the vertical blanking period approaches, the ΦVSUB pulse is stopped, and the ΦVSUB pulse is stopped.
After the horizontal scanning period, the signal charges for 8 horizontal scanning periods are transferred from the photoelectric conversion section 31 to the vertical transfer section 3 again by the charge pulse C1.
Move to 2. Therefore, signal charges for 16 horizontal scanning periods are accumulated in this vertical transfer section.

Immediately after this, the charges accumulated in this vertical transfer section are transferred to the accumulation section 33 by high-speed transfer of about IMHz during the B1 period.

Next, in the video period A1, an accumulation section vertical transfer pulse (C) is applied to the accumulation section 33 every horizontal scanning period, and the signal charges in the accumulation section 33 are transferred to the horizontal transfer section 34. At the same time, a horizontal transfer pulse (d) of a frequency that can transfer the signal charge on the horizontal transfer section 34 once is applied to the horizontal transfer section during the period between the storage section vertical transfer pulses (C), and the signal charge is transferred to the horizontal transfer section 34. It is output from the detection unit 35. As a result, a composite video signal corresponding to 1/1000 second electronic shutter is output for 8 horizontal scanning periods, that is, the accumulated charge for 1/2000 second electronic shutter is accumulated twice at approximately equal intervals, and a total of 1/1000 second electronic shutter is equivalent. When a moving object is photographed, the subject is photographed twice in one field.

If we consider a case where the amount of light on the subject is reduced to one-fourth, the output signal of the solid-state image sensor will be reduced to one-fourth, and electrical processing will be performed accordingly to reduce the amount of light to one-fourth of the current electronic shutter speed, that is, The total accumulation time is changed to 1/250th of a second.

In this case, one electronic shutter speed is fixed at 1/2000th of a second, and this is repeated eight times at equal time intervals to achieve a 1/250th of a second electronic shutter. (
(FIGS. 1(f), (g)) As described above, it is possible to adjust the sensitivity by changing the number of charge accumulations in one field period without changing the time for one charge accumulation.

In this embodiment, the sensitivity is adjusted by controlling the number of times the electronic shutter is activated for 1/2000 seconds at a time, but the electronic shutter speed may be set arbitrarily. Further, the electronic shutter speed does not need to be constant either.

Furthermore, sensitivity adjustment over multiple fields is also possible depending on the presence or absence of a high-speed vertical transfer pulse of 81 periods.

Effects of the Invention According to the present invention, when photographing a moving object, it is possible to obtain a more continuous and natural image by adjusting the sensitivity using an electronic shutter, and the practical effects thereof are extremely large.

[Brief explanation of drawings]

FIG. 1 is a drive pulse voltage waveform diagram of a solid-state imaging device in an embodiment of the present invention, FIG. 2 is a configuration diagram of a solid-state imaging device, and FIG.
The figure is a drive pulse voltage waveform diagram of a solid-state imaging device in a conventional example. (a)...Composite blanking signal, (b) (f)
......Imaging unit vertical transfer pulse, (C)...
・Storage section vertical transfer pulse, (d)...Horizontal transfer pulse, (e) (+r)...ΦVSUB pulse, AI, A2...Video scanning period, Bl, B2
...Vertical high-speed transfer pulse, C1, C2...
...Charge pulse, Di, D2...Vertical blanking period, 31...Photoelectric conversion section, 32...
...Vertical transfer section, 33...Storage section, 34...
. . . horizontal transfer section, 35 . . . signal charge detection section.

Claims (2)

[Claims] (1) A photoelectric conversion section in which a plurality of photoelectric conversion elements are two-dimensionally arranged on a semiconductor substrate, a vertical transfer section that vertically transfers signal charges accumulated in the photoelectric conversion section, and a vertical transfer section that transfers signal charges from the vertical transfer section. an accumulation section that accumulates signal charges of a plurality of horizontal lines; a horizontal transfer section that horizontally transfers signal charges for one horizontal line transferred from the accumulation section; After sweeping out unnecessary charges multiple times within one screen according to the output signal of a solid-state imaging device having a signal charge detection unit that converts into a current and outputs it, the photoelectric conversion element is operated multiple times while keeping the electronic shutter speed constant. The solid-state imaging device is characterized in that the signal charge is transferred from the vertical transfer section to the vertical transfer section and accumulated intermittently a plurality of times, and the signal charge is transferred from the vertical transfer to the accumulation section at high speed only once per screen. Sensitivity adjustment method. (2) The sensitivity adjustment method of a solid-state imaging device according to claim 1, characterized in that the signal charges are transferred at high speed from the vertical transfer section to the storage section only once for a plurality of screens, and the sensitivity is adjusted by the number of times the electronic shutter is read. .