JPH02162879A - Image pickup element driving device - Google Patents

Abstract

PURPOSE:To obtain an electronic shutter only with altering the software of an existing system by outputting a forcible accumulation control signal and a sweeping request signal from an MPU, and outputting a high-speed sweeping signal from a clock generator. CONSTITUTION:The forcible accumulation control signal is outputted from a microprocessing unit(MPU) 14 to an image pickup means 11 at a shutter time start reference time, unnecessary charge is transferred to a vertical transfer part, a sweeping request signal is outputted to a clock generator 13, the high- speed sweeping signal is outputted from the clock generator 13, and the unnecessary charge of the vertical transfer part is swept at high speed. After the forcible accumulation control signal is outputted, the signal charge accumulated in a light receiving part 11 is read by a periodical accumulation control signal and a read signal, which are outputted from the clock generator 13. Thus, only by changing a control program, the electronic shutter can be constructed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an image sensor driving device, and more specifically to an image sensor driving device that can control the charge accumulation time of an image sensor such as a CCD.

[Prior Art and its Problems 1] In recent years, various electronic still cameras have been developed that use CCD image sensors instead of conventional silver halide films. This type of electronic still camera uses a mechanical shutter similar to conventional cameras, and mechanically adjusts the shutter speed, that is, the time during which the light receiving section of the CCD image sensor receives subject light.

By the way, the CCD image sensor can obtain a shutter speed control function similar to that of a conventional mechanical shutter by changing the time interval at which charges accumulated in the light receiving section are transferred to the vertical transfer CCD, that is, the accumulation time. Therefore, in recent years, efforts have been made to reduce the weight of cameras by adopting pure electronic shutters that actively utilize this charge accumulation time adjustment.

However, the CCD image sensor used in the conventional electronic still camera has a configuration in which an accumulation control signal is periodically output to transfer the signal charges accumulated in the light receiving section to the vertical transfer COD. Therefore, a new device was provided that can output the accumulation control signal at a desired time. Providing such a new device increases the cost of the camera, which is not desirable.

[Objective of the Invention 1] The present invention has been made in view of the above-mentioned conventional problems. The purpose is to provide

[Summary of the Invention] To achieve the above object, the present invention includes an imaging means equipped with a light receiving section that converts incident light from a subject into signal charges; A regular accumulation control signal to be transferred to the transfer section is periodically output to the imaging means, and after outputting this accumulation control signal,
A readout signal for sequentially reading out the signal charges transferred to the vertical transfer section is output to the imaging means, and when a sweep request signal is input from the outside, the signal charges transferred to the vertical transfer section are output to the imaging means. pulse signal output means for outputting a high-speed sweep signal for sweeping out at high speed to the imaging means; outputting an accumulation control signal for transferring the signal charge accumulated in the light receiving section to the vertical transfer section to the imaging means at any time; The device is also characterized in that it has a control means for outputting a purge request signal to the pulse signal output means after outputting the forced accumulation control signal.

According to this configuration, under normal conditions, the pulse output means periodically sends the periodic accumulation control signal and the readout signal (
vertical and horizontal transfer signals) are output.

On the other hand, when the control means starts the shutter operation, a forced accumulation control signal is output from the control means to the imaging means at the shutter time start reference time, unnecessary charges are transferred to the vertical transfer section, and a sweep request is sent to the pulse signal output means. The signal is output, a sweep signal (high-speed vertical reverse transfer signal) is output from the pulse signal output means, and unnecessary charges in the vertical transfer section are swept out at high speed.

After the forced accumulation control signal is output from the control means, the signal charges accumulated in the light receiving section are read out by the regular accumulation control signal and readout signal output from the pulse signal output means.

The forced accumulation control signal output from the control means can be output at an appropriate timing depending on the brightness of the subject or at a timing set by the photographer.

By the above operation, a purely electronic shutter using only the imaging means can be realized.

Further, since the pulse signal output means and the control means are already existing ones, and there is no need to newly provide them, the electronic shutter can be constructed by simply changing the control program without increasing costs.

[Description of Embodiments] Hereinafter, embodiments of an image sensor driving device according to the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing a schematic configuration of an image sensor driving device.

As shown in the figure, a CCD image sensor 11 as an imaging means
, a driver 12 that drives this CCD image sensor 11.
is connected. A COD driving clock generator 13 and a microprocessing unit (MPU) 14 are connected to this driver 12 via changeover switch circuits 2OA and 20B. Note that the MPU 14 and changeover switch circuits 2OA and 20B constitute a sterilization means.

From the clock generator 13, the charges accumulated in each light receiving element (photodiode) of the CCD 1il image element 11 are transferred all at once to the vertical transfer CCD serving as a vertical transfer section at a fixed period (usually approximately 1/60 second period). A periodic accumulation control pulse as a periodic accumulation control signal and a relatively low-speed transfer pulse are respectively outputted to the switch circuit 2OA via CTG and to the switch circuit 20B via Cv and Cv4.

Further, the clock generator 13 outputs horizontal and vertical transfer signals as read signals for reading out the signal charges transferred to the vertical transfer CCD. Note that among the read signals, the vertical transfer signal is outputted via CV1 to Cv4, but the configuration related to the horizontal transfer signal is omitted from the explanation of this embodiment for the sake of simplicity.

The transfer pulses CV, to CV4 become either an accumulation control signal or a vertical transfer signal (read signal or high-speed sweep signal) depending on the level of the CTG accumulation control pulse.

Next, the configuration that is a feature of the present invention will be explained.

The MPU 14 comprehensively controls the operation of the entire drive device, and from here on, the changeover switch circuits 2OA, 2
The switching signal that causes each 0B to perform a switching operation is PS.
Output via . Depending on whether the switching signal output to this PS is "H" or "L", the connection position of the changeover switch circuits 2OA and 20B, that is, the driver 12
It is determined whether to connect the PU 14 or the clock generator 13.

In addition, from the MPU 14, the CCDtlCCD image sensor 1
A forced accumulation control pulse and a transfer pulse are output as forced accumulation control signals that cause the signal charges accumulated in each of the photodiodes 1 to be transferred all at once to the vertical transfer CCD. The forced accumulation control pulse is output to the changeover switch circuit 2OA via the PTG, and the transfer pulse is Pv, ~P■
4 to the changeover switch circuit 20B.

Further, the MPU 14 outputs a sweep request pulse as a sweep request signal to the clock generator 13 via the PHV. When this sweep request pulse is output, the clock generator 13 outputs a high-speed vertical transfer pulse as a high-speed sweep signal that sweeps out unnecessary charges at high speed to the changeover switch circuit 20B via CV1 to C4. Ru.

From the changeover switch circuit 2OA to the driver 12, the CTG or PTG accumulation control pulse output from the MPU 14 or clock generator 13 is
It is output via G.

From the switch circuit 20B to the driver 12, Cv
lNCv4 or Pvl~Pv4 transfer pulse is ■1
~v4 is output.

Transfer pulses as accumulation control signals, readout signals, or high-speed sweep signals are transmitted from the driver 12 to the CCD image sensor 11 from Φ■1 to Φ■4.
Output via .

As mentioned above, the clock generator 13 or MP
Which accumulation control pulse output from U14 is used, and whether it is MPU 14 or clock generator 13
It is up to the MPU to decide which transfer pulse output from
It is determined by the switching signal output from 14 to PS.

The transfer pulses Φv1 to Φv4 outputted from the driver 12 are either an accumulation control signal for transferring the charge of the photodiode to the CCD for vertical transfer, or an accumulation control signal for transferring the charge on the CCD for vertical transfer, depending on the level of the accumulation control pulse of the TG. This serves as a readout signal for vertical transfer or a high-speed sweep signal.

That is, when the transfer pulse is output together with the accumulation control pulse, it becomes an accumulation control signal, and when not, it becomes a readout signal or a sweep signal.

Note that the accumulated charges transferred to the vertical transfer COD are swept out to a charge sweep drain provided in the opposite direction to the horizontal transfer CCD.

The photodiode constituting the light-receiving element of the CCD image sensor 11 forms an image of the object that has entered the phototaking lens 15 and passed through the aperture 16, and the object image is captured in the form of a signal charge.

The horizontal transfer CCD of the CCD image sensor 11 includes a recording/reproducing section 18.
is connected. The recording/reproducing unit 18 records information regarding the signal charge output from the CCD 1il image element 11 as a video signal on the magnetic disk 17, or reads out and reproduces the video signal recorded on the magnetic disk 17. The operation of the magnetic disk 17 and the recording/reproducing section 18 is as follows.
Controlled by MPU 14.

Furthermore, the MPU 14 is connected to a photometry section 22 that logarithmically compresses a photometry signal from a photometry element 21 that measures the brightness of a subject, converts it into an A/D signal, and outputs it as digital photometry data. The MPU 14 calculates an optimal aperture value and shutter speed (charge accumulation time) based on the photometric data.

Further, an aperture drive circuit 23 that drives the aperture 16 and a release button 24 are connected to the MPU 14 . When an on signal is output from the release button 24, the MPU
Reference numeral 14 performs the photometric calculation, controls the aperture 16 via the aperture drive circuit 23, and drives the CCD image sensor 11.

FIG. 2 shows an example of a specific circuit of the inverting type driver 12.

As shown in the figure, Φv1 to Φv4 that drive the CCD image sensor 11 include the TG accumulation control pulse, C■,
A plurality of sets of pulse signals are output by combining the transfer pulses of ~C24.

When the TG accumulation control pulse level is "L", the changeover switch element 30 is connected to VH as shown in the figure, and when the same pulse level is "H", it is switched to connection with VM. .

When the transfer pulse level of Vl is "L", the changeover switch element 31 is in a connected state with the switch 30 as shown in the figure, and when the same level is "H", it is switched to the connection of Vi.

The changeover switch element 32 is in a connected state with 2' as shown in the figure when the transfer pulse level of 2 is "L", and is switched to the connection with VL when the same level is H".

Note that the level of the above V,,V,(V,'),VL is V
The relationship is H>Vv>VL.

The circuits related to (1) and (4) are constructed in the same way as the circuits (1) and (2) above, respectively.

The specific timing chart of the driver 12 is shown in the third section.
It is shown in the figure. When the TG accumulation control pulse is not input, the changeover switch element 30 is switched to ■2, so the transfer pulse of ■1 is inverted and output from ΦV.

From ΦVx, Φv3, and Φ■4, ■2, ■8,
The transfer pulse of V4 is inverted and output similarly to the above V1.

In the above case, the "H" level of (1) to (4) corresponds to the v, , v, level of ΦV1 to (ΦV4), and the "L" level of the same corresponds to the vL level.

Further, when the TG accumulation control pulse is input, the changeover switch element 30 changes to ■ as shown in the figure. , so V
,, when the level of V is “L”, Φ■1, Φ■,
The level becomes ■.

As explained above, ΦV and Φ■ are three-value signals, and when ΦV3 and Φ■ are at the highest level, v,4, they become accumulation control signals, and the charge accumulated in the photodiode is transferred to the COD for vertical transfer. Transfer to. On the other hand, Φ■1～
When the level of Φ■4 takes on levels ■2, ■2', and ■, a vertical transfer pulse is generated, and the charge transferred to the vertical transfer COD is sequentially transferred onto the vertical transfer CCD.

Next, the specific operation of the image sensor control device of the present invention configured as described above will be explained based on the flowchart shown in FIG. 4. Note that this flowchart will be explained with reference to the schematic configuration diagram in FIG. 1 and the timing charts in FIGS. 5 and 6.

First, when the release button 24 is turned on, the MPU 14
sets the PS switching pulse to "H" and sets the PHV sweep request signal to "L" (step 51).
．． 52). With this set, the clock generator 13 is connected to the driver 12, and from the clock generator 13, as shown in FIG.
It is output to Vl-C4. In other words, the image of the subject is read out from the CCD image sensor 11 at a cycle of 1760 seconds,
It will be output to the recording/playback section 18.

Then, the MPU 14 performs a photometric calculation based on the photometric data regarding the brightness of the subject outputted from the photometric section 22 (step 53), and determines the optimal aperture value AV and shutter speed TV. Then, the aperture drive circuit 23 is controlled based on the optimum aperture value AV, and the aperture 16 is set to the optimum aperture value (steps 54 and 55).

When the setting of the aperture 16 is completed, the MPU 14 waits until the pulse of VD shown in FIG. 5 becomes H'', and then sets the switching pulse PS to L'' (step 56 and 57). , 20B are switched, the MPU 14 is connected to the driver 12, and the MPU 1
4, it becomes possible to output forced accumulation control pulses and transfer pulses. In other words, the driver 12 is in a state where it can output the accumulation control signal.

When the optimum shutter speed TV calculated in step 53 is obtained, the MPU 14 applies a forced accumulation control pulse to the PTG, as shown in FIGS.
A transfer pulse is output to Pv4. This allows the CCD
The unnecessary charges accumulated in the light receiving section of the image sensor 11 are transferred all at once to the vertical transfer CCD (step 58). When the forced accumulation control pulse is outputted faster than 1760 seconds, the next periodic accumulation control pulse is output from the clock generator 13, and when it is slower than 1760 seconds, the periodic accumulation control pulse of several lights is output. It can be determined by calculating the shutter speed TV from .

Then, the MPU 14 determines that the VD pulse shown in FIG.
Wait until it rises to "H", then switch the PS switching pulse and P
The HV high-speed transfer pulse request signal is set to "H" (steps 59 and 60).

As a result, from the clock generator 13, C■1 to C
■ A high-speed sweep pulse is output at 4 for a predetermined time, and a transfer pulse as a high-speed sweep pulse is output from the driver 12 to Φ
The unnecessary charge that is output to the CCD image sensor 11 via vI to Φ■ and transferred to the vertical transfer CCD of the CCD image sensor 11 is swept out at high speed. This high-speed sweep pulse ends before the next regular accumulation control pulse is output from the clock generator 13.

When the next periodic accumulation control pulse is output from the clock generator 13 to the CTG, the signal charges accumulated during the optimum shutter speed TV time are transferred to the vertical transfer CCD. M
After the transfer, the PU 14 opens the REC gate of the recording/reproducing section 18 and starts recording the signal charge (step 61).
. That is, signal charges sequentially output from the vertical transfer CCD in response to vertical and horizontal transfer signals output from the clock generator 13 are recorded on the magnetic disk as a video signal via the recording/reproducing section 18.

When recording for one screen is completed, the PHV sweep request pulse is set to "L" to return to the initial state (steps 62 and 63).

As described above, according to this embodiment, the forced accumulation control signal that controls the shutter time and the sweep request signal that sweeps out unnecessary charges are output from the existing MPU 14, and the high-speed sweep signal for sweeping out unnecessary charges is output from the existing MPU 14. Since it is output from the clock generator 13, a pure electronic shutter can be obtained by simply changing the software of the existing system.

In the above embodiments, an incline transfer type CCD image sensor that does not have a memory area is exemplified as the type of CCD image sensor, but the present invention is not limited to this, and even if there is a type that has a memory area, the present invention is not limited to this. Applicable.

Further, in this embodiment, an example of automatic exposure control in which the shutter speed changes depending on the brightness of the subject was shown, but the present invention
A configuration in which the shutter speed is manually set may also be used.

[Effects of the Invention] As is clear from the above description, according to the image sensor driving device of the present invention, an accumulation control signal for controlling the signal charge accumulation time of an image capturing means such as a CCD, and a method for sweeping out unnecessary charges at high speed. The high-speed transfer request signal is a readout signal that is output from the existing control means and reads out an image signal from the imaging means, and the high-speed sweep signal is output based on the sweep request signal output from the control means. Since the pulse signal is output from the existing pulse signal output means, an electronic shutter that can control the shutter speed can be realized using only the existing device without installing a new device.

Timing chart: FIG. 4 is an operation flowchart of the image sensor drive device shown in FIG. 1; FIGS. 5 and 6 are timing charts of each part of the image sensor drive device shown in FIG. 1. .

11... CCD image sensor (imaging means), 12... Driver (pulse signal output means), 13... Clock generator (pulse signal output means), 14... MPU (control means), 2OA, 20B ...changeover switch circuit (control means)
.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an image sensor driving device according to the present invention, FIG. 2 is a diagram showing an example of a specific circuit of an inversion type driver, and FIG. Asahi Optical Industry Co., Ltd.'s agent Kunio Miura ψ− is the patent applicant for the inverted type driver shown in the figure. Figure 1 Figure 2 Figure 3 Figure 4 Director General of the Patent Office Yoshi 1) Moon Yi 1. Display of the case 1986 Patent Application No. 317374 2, Name of the invention Person who corrects the drive device of an image sensor 3° Relationship to the case Patent applicant address 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Name (
052) Asahi Optical Industry Co., Ltd. Representative: Toru Matsumoto 4, Agent address: 116 Niban-cho, Chiyoda-ku, Tokyo 102 Contents of amendment (1) On page 16, line 12 of the specification attached to the application, r
1/60 sec" was replaced with ``Shutter speed TV is 1/60 sec.
/60 seconds”. (2) On page 18, line 15 of the same specification, the statement "even if it has" is amended to read "even if it has". (3) On page 19, line 5 of the same specification, the description "high-speed transfer request signal" is corrected to read "sweeping request signal."(that's all)

Claims (2)

[Claims] (1) An imaging means equipped with a light receiving section that converts incident light from a subject into a signal charge and accumulates the signal charge, and an accumulation control signal that transfers the signal charge accumulated in the light receiving section to the vertical transfer section during normal operation. After outputting this periodic accumulation control signal, a readout signal for sequentially reading out the signal charges transferred to the vertical transfer section is outputted to the imaging means, while a sweep request signal is received from the outside. When the signal charges are input, pulse signal output means outputs to the imaging means a high-speed sweep signal for sweeping out the signal charges transferred to the vertical transfer section at high speed; It is characterized by comprising a control means that outputs a forced accumulation control signal to be transferred to the transfer section to the imaging means at any time, and outputs a sweep request signal to the pulse signal output means after outputting the forced accumulation control signal. A driving device for an image sensor. (2) Claim 1, further comprising a switching means for selectively switching the accumulation control signal inputted to the imaging means to a signal from the pulse signal output means or the control means, the switch circuit comprising: a signal from the control means; 1. A driving device for an image sensor, characterized in that the driving device is controlled by.