JPS63107377A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To obtain a high shutter speed by issuing exhaust signals repeatedly after issuing a timing signal in order to exhaust charges accumulated in a photoelectric conversion part as unnecessary charges by means of high speed transmitting signals. CONSTITUTION:If a shutter commanding signal is inputted to a drive pulse switching signal generator 5, the generator 5 transmits a switching signal to a high-speed pulse switcher 4 normally at this time, so that the status in which normal drive pulses are transmitted normally to the switcher 4 and a CCD drive circuit 2 from a CCD drive pulse generator 6 is shifted to a status in which high-speed drive pulses are issued by a high-speed drive pulse generator 7 for unnecessary charge exhaust. Thereafter, one scene share of charges accumulated in a PD for photoelectric conversion are transmitted to a CCD register by means of read pulses issued sequentially with a short interval time, and thus exhausted by the high-speed transmitting pulses.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a solid-state imaging device, more specifically, to a solid-state imaging device such as an electronic camera that extracts signal charges accumulated in a photoelectric conversion section as an image signal at an arbitrary timing. It relates to an imaging device.

[Prior Art] Conventionally, in a solid-state imaging device such as an electronic camera, an electronic shutter operation by COD drive is performed as shown in FIG. In other words, if unnecessary charge is accumulated in the photoelectric conversion photodiode (hereinafter referred to as PD) of the COD to a saturation level, a read pulse is given at the start of the shutter operation, and at this point the CCD register is read. The applied transfer pulse shifts from the normal transfer speed frequency to the high speed transfer frequency, and unnecessary charges accumulated in the photoelectric conversion PD are discharged at high speed. By this high-speed transfer, the next signal charge is accumulated as an effective charge in the photoelectric conversion PD during the time when the unnecessary charge is discharged. Then, when the next read pulse is applied after the shutter time t, the effective charge is normally transferred to the CCD register by the normal speed transfer pulse, and an image output corresponding to the shutter time t is output from the CCD register. be done.

[Problems to be Solved by the Invention] Incidentally, in the above-mentioned conventional solid-state imaging device, the shutter time t is shorter than the time t required for all unnecessary charges accumulated in the photoelectric conversion PD to be discharged to a saturation level. I can't. In other words, the minimum value of shirt short time t is t
(min), the value of S t (mIn) is limited by the time t required to quickly discharge the unnecessary charges. If the shutter time tS is made shorter than the above time t, some of the unnecessary charge that could not be completely discharged will remain in the CCD register and mix with the effective charge at the shutter time t, resulting in image deterioration. Become. Furthermore, since there is a limit to high-speed driving of the CCD register due to reasons such as a decrease in transfer efficiency, the above-mentioned time t.

itself cannot be shortened, and the shirt time cannot be increased beyond a certain value.

The present invention has been made with attention to such problems, and is designed to obtain a high-speed shutter time by making the minimum value of the shutter time sufficiently shorter than the time for discharging unnecessary charges accumulated to the saturation level. The purpose of the present invention is to provide a solid-state imaging device with improved performance.

[Means for Solving the Problems] The solid-state imaging device of the present invention includes means for generating a timing signal for reading charges accumulated in a photoelectric conversion section, and a means for generating a high-speed transfer signal after the timing signal is generated. means for generating, after the timing signal is issued, a means for repeatedly generating a discharge signal for discharging the accumulated charge as a non-f7 load by the high-speed transfer signal; It consists of a means for extracting the charges accumulated in the photoelectric conversion section as an image signal.

[Function] When the timing signal is issued, the discharge signal is then repeatedly issued, and the charges accumulated in the photoelectric conversion section are discharged as unnecessary charges by the high-speed transfer signal, and the charges that were accumulated after the last discharge signal is generated are discharged as unnecessary charges. The charge is extracted as an image signal.

[Embodiment] An electronic camera, which is a solid-state imaging device of the present invention, is configured as shown in the block diagram shown in FIG. 1, for example. In FIG. 1, the CCD imaging element 1 is supplied with vertical register drive pulses φV to φV, horizontal register drive pulses φH1゜l4ゝφH2, reset pulse φR, etc. by the CCD drive circuit 2, and these pulses Accumulation of signal charges in the photoelectric conversion photodiode of the CCD image sensor 1,
Image output is read by transferring the accumulated charges to the CCD register and transferring signal charges from the register.

The CCD drive circuit 2 is supplied with a read pulse from a read pulse generator 3 at a timing to be described later, and is also supplied with a drive pulse for transfer from a normal/high speed pulse switch 4. The normal/high-speed pulse switching device 4 receives the switching signal from the drive pulse switching signal generator 5 to
Drive pulses for normal transfer inputted from the CD drive pulse generator 6 and high-speed drive pulse generator 7 for unnecessary charge discharge
The drive pulses for high-speed transfer, which are more manually input, are switched and one of the drive pulses is sent to the CCD drive circuit 2.

The read pulse generator 3 receives a shutter command signal and t
Counter C, t Counter C2,..., t
Counter C, t Counter C n-1n-1n
By inputting the n can output signals, a read pulse is generated at the timing of each of these signal inputs. The t counter C1 starts counting after the shutter command signal is issued, and outputs an output when the time t1 set in advance by the setter R1 has been counted. t
Counter C2 is a time 1 set in advance by setting aR2 after the count output of tl counter C1 is issued.
(<11), a count output is generated.

Thereafter, counter outputs are sequentially issued at short time intervals in the same manner, and the t counter C at the last stage corresponds to the t at the previous stage. −
A count output is generated when a time 1 (<1°-1)n preset by the shutter time setting device R has elapsed after the output of the counter C1-1 is generated. The output signal of the last stage t counter C and the previous stage n
n tn-1 Time interval t with the output signal of counter Cn-1
corresponds to the shutter time, and the shutter time setting device R can be set to a value corresponding to an arbitrary shutter speed prior to photographing. Further, the shutter command signal and the n output signal of the t counter C at the last stage are inputted to the drive pulse switching signal generator 5 as a trigger signal for generating a switching signal.

Next, the operation of the electronic camera shown in FIG. 1 will be explained with reference to the time chart shown in FIG.

When a release switch for performing a shutter operation is turned on, a shutter command signal is issued. When this shutter command signal is input to the drive pulse switching signal generator 5, the drive pulse switching signal generation W5 is normal at this point.
Since the switching signal is sent to the high-speed pulse switching device 4, normal
The high-speed pulse switch 4 connects the CCD drive circuit 2 to the CCD drive circuit 2.
The state in which the normal drive pulses generated by the OD drive pulse generator 6 are sent out is switched to the state in which the high speed drive pulses generated by the unnecessary charge discharge force 1 high speed drive pulse generator 7 are sent out.

Furthermore, when the shutter command signal is input to the readout pulse generator 3, the first readout pulse is sent to the CCD at this point.
Since the signal is sent to the drive circuit 2, the CCD drive circuit 2 superimposes the readout pulse on the drive pulse (transfer pulse) for high-speed transfer emitted from the normal/high-speed pulse switch 4 at this time, and outputs the readout pulse to the CCD imaging probe 1. Send to. Then, C
The charge ■ that has been accumulated in the photoelectric conversion PD of the CD image sensor 1 is transferred as an unnecessary charge to the CCD register at the time when the above-mentioned read pulse is applied, and is transferred within the same COD register by the above-mentioned high-speed transfer pulse. be discharged. Thereafter, after a time t1 has elapsed since the shutter command signal was input, that is, from the time when the first read pulse was emitted, the read pulse generator 3 outputs the second read pulse.
A read pulse is emitted. Here, the above time t1
is a slightly longer time than the time t required to discharge all of the charges as unnecessary charges when the charges (2) have been accumulated in the photoelectric conversion PD to a saturation level. When the second read pulse passes through the CCD drive circuit 2 and is superimposed on the high-speed transfer pulse and is input to the CCD image sensor 1, it accumulates in the photoelectric conversion PD during the high-speed transfer at time t1 to discharge the first unnecessary charge (■). The generated charge (2) is transferred to a CCD register, and is transferred and discharged as an invalid charge by a high-speed transfer pulse. The time required to completely discharge the invalid charge ■ accumulated during the above time t1 may be shorter than the time required to discharge all the unnecessary charges ■ at the saturation level, so the time is shorter than the above time t1. By the time t2 has elapsed since the generation of the second read pulse, all of the invalid charge ■ has been discharged, and at the same time, the third read pulse is generated. When the third read pulse is issued, the invalid charges (2) accumulated in the photoelectric conversion PD during the above-mentioned time t2 are transferred to the CCD register and then discharged by high-speed transfer. The time required to discharge all of the invalid charges ■ accumulated during time t2 may be shorter than the time required to discharge all of the invalid charges ■ accumulated during the previous time t1. After a comparatively shorter time t3 has elapsed, all of the invalid charges 3 are discharged, and at the same time a fourth read pulse is generated.

Thereafter, in the same manner, charges for one screen accumulated in the photoelectric conversion PD are sequentially transferred to the CCD register by readout pulses emitted at short time intervals, and discharged by high-speed transfer pulses. Therefore, during time tn-1, PD1 for photoelectric conversion. :The time required to discharge the accumulated invalid charge ■ by a high-speed transfer pulse is only a short time, so
The charge accumulated in the photoelectric conversion PD from the time when this invalid charge (2) is transferred to the CCD register by the n-1th read pulse is used as the effective charge by the shutter operation. That is, from the point in time when the (n-1)th read pulse is issued, the nth read pulse is issued when the above-mentioned invalid charge (2) is completely discharged by the high-speed transfer pulse and time t has elapsed. This number 0 [
The read pulse of l is obtained by the output of the t counter C, but n n The output of this t counter C is the driving pulse switch n
Since the No. n generator 5 is also manually powered, the drive pulse switching signal generator 5 sends a switching signal to the normal/high speed pulse switch 4 at this time, and the normal/high speed pulse switch 4 receives the signal from the CCD drive pulse generator 6. A normal transfer pulse is sent to the CCD drive circuit 2. Therefore, at the time when the n-th read pulse is issued, the charge accumulated in the photoelectric conversion PD during the time t is transferred to the COD register as an effective charge, and is normally transferred to the COD register by the transfer pulse at the normal speed. The image signal is transferred from the CCD image sensor 1 as an image signal with a shutter time t.sub.1.

In this way, by dividing the charges accumulated in the photoelectric conversion PD into unnecessary charges and repeatedly discharging them by high-speed transfer, the accumulation time of the charges finally accumulated in the photoelectric conversion PD is shortened. However, since the previously accumulated unnecessary charge can be discharged within this charge accumulation time, the effective charge time t 1 , that is, the shutter time t can be made n shorter. For example, while the shutter time t (a+in) in the conventional electronic camera described above can be at most 11,500 shutter seconds, in the above embodiment it is 1/1000 to 1/20.
00 high speed shutter speeds can be obtained.

The above-mentioned time t can be set to any desired shutter speed by the photographer using the shutter time setting device R, and of course can be set not only to a high speed shutter speed but also to a low speed shutter speed.

In the above embodiment, the readout pulse for discharging unnecessary charge is emitted from the time when the first readout pulse is emitted by the shutter command signal and discharge of unnecessary charge is started until the accumulation of effective charge finally starts. Set the time interval to tt > t
2>ts,...Snow. -1 and gradually become shorter, but the present invention does not necessarily require different discharge time intervals in this way, and read pulses for unnecessary charge discharge are repeatedly emitted at short equal time intervals. You can do it like this.

Further, in the solid-state imaging device of the present invention, C
OD can also be applied.

[Effects of the Invention] As described above, according to the present invention, the minimum value of the shutter time can be made sufficiently shorter than the time for discharging unnecessary charges at saturation, and good images can be taken even at high shutter speeds. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a solid-state imaging device showing an embodiment of the present invention, FIG. 2 is a time chart for explaining shutter operation in the device shown in FIG. 1, and FIG. 3 is a conventional solid-state imaging device. 3 is a time chart for explaining shutter operation in the solid-state imaging device of FIG. 1... CCD image sensor (photoelectric conversion unit, image signal generation means) 2... CCD drive circuit (image signal generation means) 3... ... Read pulse generator (means for generating timing signals, ejection signal generation means) 4 ..... Normal/high speed pulse switch (means for generating high speed transfer signals) 7 .....・High-speed drive pulse generator for discharging unnecessary charges (high-speed transfer signal generation means)

Claims (1)

[Claims] Means for generating a timing signal for reading signal charges accumulated in a photoelectric conversion section, and after the timing signal is generated, generating a transfer signal at a faster rate than a normal transfer rate. a high-speed transfer signal generating means for generating a high-speed transfer signal; and a discharge signal generating means for repeatedly generating a discharge signal for discharging the electric charge accumulated in the photoelectric conversion section as an unnecessary charge by the high-speed transfer signal after the timing signal is generated. A solid-state imaging device comprising: and image signal generation means for extracting the charge accumulated in the photoelectric conversion unit as an image signal after the generation of the last discharge signal.