JPH02166974A - Driving device for image pickup element - Google Patents

Abstract

PURPOSE:To eliminate the difference of smear levels in a movie mode and a still mode by outputting a sweeping-out signal from a pulse signal output means at every field when a sweep-out requesting means is turned on. CONSTITUTION:To an image pickup means 11, a periodical accumulation control means and reading signal are periodically outputted from a pulse signal output means 13 at a normal time and a signal charge is transferred from a vertical transferring part at usual speed. On the other hand, at the time of electronic shutter operation, a forcible accumulation control signal is outputted from a control means 14 to the image pickup means 11 and a sweep-out requesting signal is outputted to the pulse signal output means 13. Then, the unnecessary charge of a light receiving part is transferred to the vertical transferring part and swept out in a short time. At the time of the movie mode, when a sweep-out requesting signal output means 25 is operated, a sweep-out signal is outputted from the pulse signal output means 13 at every field and the unnecessary charge remaining in the vertical transferring part is swept out in a short time. Thus, the smear level is made uniform in the movie mode and still mode.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a driving device for an image sensor in an electronic still camera that can continuously monitor in movie mode and record one image at a time in still mode.

"Prior Art and its Problems" In recent years, various electronic still cameras have been developed that use CCD image sensors instead of conventional silver halide films. This C
The CD image sensor can provide the same shutter speed control function as a conventional mechanical shutter by changing the time interval at which the charges accumulated in the light receiving section are transferred to the vertical transfer CCD (vertical transfer section), that is, the accumulation time. . So recently,
We are trying to reduce the weight of the camera by adopting a purely electronic shutter that actively utilizes this charge accumulation time adjustment.

In order to reduce costs, conventional electronic still cameras use an incline transfer type CCD image pickup element and drive device, which is similar to the image pickup unit used in video cameras.

In this CCD imaging unit for a video camera, the signal charges accumulated in the light receiving section are periodically (every 1/60 seconds) simultaneously transferred to the vertical transfer COD (vertical transfer section), and the signal charges are transferred to the vertical transfer COD (vertical transfer section). They are sequentially read out before the next periodic transfer of signal charges is performed. Transfer to the vertical transfer CCD is performed by a regular accumulation control signal, and reading is performed by a read signal consisting of vertical and horizontal transfer signals.

During electronic shutter operation, signal charges are forcibly transferred at a predetermined timing, and exposure is started. The unnecessary charge transferred to the vertical transfer CCD is swept out in a short time immediately before the periodic accumulation control signal is output. and,
The signal charge accumulated in the light receiving section after the forced transfer described above and before the periodic transfer (exposure time) is transferred to the vertical transfer CCD by a periodic accumulation control signal, and is transferred to the vertical transfer CCD by a periodic readout signal. They are read out in order.

When such a purely electronic shutter is adopted, the signal charges accumulated in the light receiving section are periodically read out at the smear level in the movie mode, and when the electronic shutter is operated, charges are accumulated for a time corresponding to the shutter speed. Thereafter, the smear level in the still mode in which signal charges accumulated within this time are read out is different, and the image becomes unbalanced.

For example, in the movie mode, a periodic accumulation control signal for transferring signal charges from the light receiving section to the vertical transfer CCD is outputted every 1/60 seconds, and then read out by a readout signal. Therefore, signal charges that could not be read out in the previous frame may remain in the vertical transfer CCD.

However, when capturing an image with a shutter speed of 1760 seconds in still mode, after the forced accumulation control signal is output and immediately before the periodic accumulation control signal is output, the vertical transfer C
The charge transferred to OD is swept out. Therefore, unnecessary charges hardly remained in the vertical transfer CCD.

In other words, the smear level tends to be higher in the movie mode, even though the charge accumulation time is the same.

Since such unbalance is undesirable, it is necessary to perform circuit adjustment, but this circuit adjustment is extremely difficult and time-consuming.

``Object of the Invention'' The present invention has been made in view of such conventional problems, and it is possible to control the charge accumulation time of the imaging means,
Another object of the present invention is to provide an image pickup device driving device that facilitates adjustment to make the smear level the same in movie mode and still mode.

"Summary of the Invention" To achieve the above object, the present invention includes a light receiving section that converts incident light from a subject into signal charges and accumulates them, and a vertical an imaging means including a transfer section; under normal conditions, an accumulation control signal for transferring the signal charges accumulated in the light receiving section to the vertical transfer section is periodically outputted to the imaging section; After the output, a readout signal for sequentially reading out the signal charges transferred to the vertical transfer section of the imaging means is outputted to the imaging means, and when a sweep request signal is input from the outside, a readout signal is sent to the vertical transfer section of the imaging means. pulse signal output means for outputting a sweep signal for sweeping out the transferred charges in a short time to the imaging means at a predetermined time and for a predetermined time; forced accumulation for transferring the signal charge accumulated in the light receiving section to the vertical transfer section; A control means for outputting a control signal at an arbitrary timing and a sweep request signal to the pulse signal output means; and a sweep request signal output means for outputting a sweep request signal to the pulse signal output means. It is characterized by:

Therefore, during normal operation (movie mode), the pulse signal output means periodically outputs a periodic accumulation control signal and a readout signal to the imaging means, and the vertical transfer section transfers signal charges at a normal speed. It is done.

On the other hand, when the electronic shutter is operating (in still mode), the control means outputs a forced accumulation control signal to the imaging means, and a sweep request signal is output to the pulse signal output means, thereby eliminating unnecessary charges in the light receiving section. It is transferred to the vertical transfer section and swept out in a short time. This realizes an electronic shutter using only the imaging means.

If the sweep request signal output means is activated in the movie mode, the pulse signal output means outputs a sweep signal every 1 fields, and unnecessary charges remaining in the vertical transfer section are swept out in a short time.

As a result, the smear level in movie mode and still mode is made uniform, and uniform images can be obtained in movie mode and still mode.

"Embodiments of the Invention" Examples of the driving device for an image sensor according to the present invention will be described in detail below with reference to the drawings.

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

As shown in the figure, a CCDCD element 11 as an imaging means, and a driver 12 that drives this CCD image sensor 11.
is connected. The driver 12 includes a CCD driving clock generator 13 as a pulse signal output means and a microprocessing unit (MPU) as a control means via changeover switch circuits 2OA and 20B.
)14 are connected. Note that the MPU 14 and changeover switch circuits 2OA and 20B constitute a control means.

The CCD image sensor 11 uses an interline transfer method, and a subject image that enters through the photographing lens 15 and passes through the aperture 16 is formed on each photodiode constituting the light receiving section, and the subject image is converted into a signal charge. captured in the form of

The aperture 16 and an aperture adjustment circuit 23 whose drive is controlled by the MPU 14 constitute an aperture adjustment means.

The signal charges accumulated in the photodiodes are simultaneously transferred to a vertical transfer CCD serving as a vertical transfer section. The charges transferred to the vertical transfer CCD are sequentially transferred to the horizontal transfer CCD during readout, read out from the horizontal transfer COD every horizontal line, and when swept, the charges are transferred to the horizontal transfer CCD.
It is swept out by a sweep-out train provided on the opposite side from D.

The horizontal transfer CCD of the CCD image sensor 11 includes a recording/reproducing section 1.
8 are connected. The recording/reproducing unit 18 records information regarding the signal charge output from the CCD image sensor 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 PU14.

An electronic viewfinder 28 is connected to the recording/reproducing section 18 , and images input to the recording/reproducing section 18 can be viewed on this electronic viewfinder 27 .

The MPU 14 includes a photometric element 2 that measures the brightness of the subject.
A photometry section 22 is connected which logarithmically compresses the photometry signal from 1, performs A/D conversion, 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, the MPU 14 is connected to a release button 24 and a sweep switch 25 as a sweep request signal output means. When an on signal is output from the release button 24, the MPU 14 performs the photometric calculation, controls the aperture 16 via the aperture drive circuit 23, drives the CCD image pickup device 11, and performs video recording.

When the on signal is output from the sweep switch 25, M
The PU 14 outputs a sweep request signal to the clock generator 13 via the PHV.

Next, the configuration and operation related to the signals that drive the CCD image sensor 11 will be explained.

The clock generator 13 periodically outputs an accumulation control pulse as a periodic accumulation signal, a relatively low-speed transfer pulse, and a readout pulse as a readout signal for reading out the signal charge transferred to the vertical transfer CCD. .

The periodic accumulation control pulse and the low-speed transfer pulse are activated at constant intervals (1760 seconds), and the charges accumulated in the light receiving section of the CCD image sensor 11 are transferred all at once to the vertical transfer COD.

The readout pulse is periodically output while the periodic accumulation control pulse is output, and reads out the charge transferred to the vertical transfer CCD.The readout pulse reads out the signal charge transferred to the vertical transfer CCD. It consists of a vertical transfer pulse that sequentially moves to the horizontal transfer COD, and a horizontal transfer pulse that reads out the signal charge of the horizontal line transferred to the horizontal transfer CCD. I won't explain the pulse.

Furthermore, from the clock generator 13, a vertical transfer C
A high-speed transfer pulse is output as a sweep signal that sweeps out the charge on the CD in a short time. This high-speed transfer pulse is M
On the condition that the sweep request pulse is input from the PU 14, the pulse is output for a predetermined time after the output of the read pulse is finished, and the output ends before the next periodic accumulation control pulse is output.

The periodic accumulation control pulse is outputted to the changeover switch circuits 2OA and 20B via CTG, and both transfer pulses and read pulses are outputted via CVI to Cv4, respectively.

The pulses output to Cv, to C4 are either an accumulation control signal or a vertical transfer signal (a read signal or a high-speed sweep signal) depending on the level of the CTG accumulation control pulse.

The MPU 14 comprehensively controls the operation of the entire drive device, and a switching pulse is output from here via the PS. The switching pulse output to this PS is “H”
or L″, the changeover switch circuit 2OA,
The connection position of the driver 20B, that is, whether the MPU 14 or the clock generator 13 is connected to the driver 12 is determined.

The MPU 14 transfers the signal charges accumulated in each photodiode of the light receiving section of the CCD image sensor 11 to the CC for vertical transfer.
The forced accumulation control pulse as a forced accumulation control signal and the 0 forced accumulation control pulse from which the transfer pulse is output are transferred to the changeover switch circuit 2 via the PTG.
The transfer pulse is output to the changeover switch circuit 20B via PV+ to PV4.

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 transfer pulse as a high-speed sweep signal that sweeps out unnecessary charges at high speed as described above to the changeover switch circuit 20B via CV1 to Cv4. Ru.

As already explained, when the on signal is output from the sweep switch 25, the MPU 14 sends a sweep request pulse to the clock generator 1 via the PHV.
Output to 3. The clock generator 13 that receives this sweep request pulse PHV sends a high-speed sweep pulse to the CCD image sensor 11 via the changeover switch circuit 20B to sweep out the charge of the vertical transfer COD at high speed every field. It is output for a predetermined time after the end of output of the read pulse, and is sent to the CCD for vertical transfer every l frame.
Sweeping is executed.

FIG. 2 shows the MPU 14 around the sweep switch 25.
The specific circuit inside is shown. The sweep switch 25 is input to one input of the OR gate 26, and the still/movie switching signal inside the MPU 14 is input to the other input. The still/movie switching signal is
A signal within the MPU 14 that is “H” in still mode.
When in movie mode, it becomes L”.

The output of the OR gate 26 is input to one of the inputs of the AND gate 27. The other input of the AND gate has
A sweep request signal within the MPU 1J is input. This sweeping request signal is output periodically at a predetermined timing in the movie mode, and is output once at a predetermined timing in the still mode. The output of the AND gate 27 is PHV.

Therefore, in the movie mode, the PHV periodically outputs a sweep request pulse on the condition that the "H" signal (on signal) is output from the sweep switch 25, and in the still mode, the sweep request pulse is output at a predetermined time. A request pulse is output.

The CTG or PTG accumulation control pulse output from the MPU 14 or the clock generator 13 is alternatively output from the changeover switch circuit 2OA to the driver 12 via the TG.

From the switch circuit 20B to the driver 12, MP
Transfer pulses CV1 to CV4 or Pv1 to PV4 outputted from U14 or the clock generator 13 are alternatively outputted via 1 to v4.

Then, from the driver 12 to the CCD image sensor 11, a transfer pulse as an accumulation control signal, a readout signal, or a high-speed sweep signal is transmitted from ΦVI to Φv4.
Output via .

As mentioned above, the clock generator 13 or MP
The MPU determines which accumulation control pulse output from LI 14 is used and which transfer pulse is used.
14 via the PS.

The transfer pulses Φv1 to Φv4 output from the driver 12 are either accumulation control signals for transferring the charge of the photodiode to the vertical transfer CCD, or transfer the charges on the vertical transfer CCD to the vertical transfer, depending on the accumulation control pulse level of the TG. This serves as a readout signal for 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.

FIG. 3 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 and CV1.
A plurality of sets of pulse signals are output by combining the transfer pulses of ~Cv4.

When the TG accumulation control pulse level is "Lo", 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 any connection.

The changeover switch element 31 is connected to the switch 30 as shown when the transfer pulse level of vl is "L", and is switched to the connection with VL when the level is "H".

The changeover switch element 32 is connected to v,' as shown in the figure when the transfer pulse level of (1) is "L", and is switched to Vt, which connection is made when the same level is "H".

Note that the above V, , V, (VM'), and VL (7) levels have a relationship of Vs>VM (Vll')>VL.

The circuits related to (2) and v4 are constructed in the same way as the circuits for V1 and V, respectively.

A specific timing chart of the driver 12 is shown in FIG. When there is no input of the TG accumulation control pulse, the changeover switch element 30 is switched to Vv, so the transfer pulse of vl is inverted and output from Φv1.

From ΦV l , ΦVs, and Φv4, v, , V
The transfer pulses s and v are inverted and output in the same way as v1 above.

In the above case, the "H" level of (1) to v4 corresponds to the VM%v11 level of ΦV and to Φv4, and the "L" level of the same corresponds to the vL level.

Furthermore, when the TG accumulation control pulse is input, the changeover switch element 30 switches to v8 as shown in the figure, so that V
, , when the level of V is "L", ΦV1, Φvs
level becomes vH.

As explained above, Φv1 and ΦV are three-value signals, and when Φv1 and ΦV are at the highest level vH, they become accumulation control signals, and the charges accumulated in the photodiodes are transferred to the vertical transfer CCD. On the other hand, ΦV1~
When the level of Φv4 reaches v,,v,'' and vL, it becomes a vertical transfer pulse, and the charges transferred to the vertical transfer CCD are sequentially transferred on the vertical transfer CCD.

Next, a specific electronic shack 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.

Note that this flowchart will be explained with reference to the schematic configuration diagram of FIG. 1 and the timing chart of FIG. 6.

First, when the release button 24 is turned on, the MPU 14
sets the PS switching pulse to “H” and the PHV sweep request pulse to “L” (step 5).
1.52) With this set, the clock generator 13 is connected to the driver 12, and the clock generator 13 sends periodic accumulation control pulses to the CTG at a cycle of 1/60 seconds, as shown in FIG. , transfer pulses are output to C1 to CV4. In other words, the image of the subject is read out from the CCD image sensor 11 at a cycle of 1760 seconds and output to the recording/reproducing 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 for the VD pulse shown in FIG. 5 to become "H", and then sets the PS switching pulse to "L" (steps 56 and 57).
As a result, the switch circuits 2OA and 20B switch and operate, the MPU 14 is connected to the driver 12, and the MPU
14, 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 forced accumulation control pulses to the PTG, Pv, ~Pv, as shown in FIGS. 6 and 7.
4 outputs a transfer pulse. As a result, unnecessary charges accumulated in the light receiving section of the CCD image sensor 11 are transferred all at once to the vertical transfer CCD (step 58). When the above forced accumulation control pulse is output, the shutter speed TV is l/
When faster than 60 seconds, the clock generator 13
If it is late, the shutter speed TV can be determined by back calculating the shutter speed TV from the time when the next periodic accumulation control pulse is output.

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 sweep request pulse is set to "H" (step 59.60). As a result, the clock generator 13 outputs a high-speed sweep pulse to C■ to Cv4 for a predetermined time, and the driver 12 outputs a high-speed transfer pulse to Φvl.
.about.Φv2 to the CCD image sensor 11, and unnecessary charges transferred to the vertical transfer COD of the CCD image sensor 11 are swept out at high speed.

This high-speed transfer pulse ends before the next periodic 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 image charge accumulated for the optimum shutter speed TV waiting time is transferred to the vertical transfer CCD.

After the transfer, the MPU 14 opens the REC gate of the recording/reproducing section 18 and starts recording the image charge (step 61).
), that is, signal charges sequentially output from the vertical transfer COD in response to read pulses output from the clock generator 13 are recorded (recorded) on the magnetic disk 17 as a video signal via the recording/reproducing section 18 .

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

The above is the shutter operation in a state where the sweep switch 25 is not turned on. When the sweep switch 25 is turned on, a sweep request pulse is constantly output to the clock generator 13 as shown in FIG. is output. Therefore, the smear level can be easily adjusted between the still mode and the movie mode by turning on this switch 25.

Furthermore, when a high-brightness subject is being monitored in the movie mode, turning on the sweep switch 25 lowers the smear level of the image in the electronic viewfinder 28, making it less unsightly. Furthermore, power consumption can be saved by turning off the sweep switch 25.

In the above embodiments, an interline transfer type CCD image sensor without a memory area is illustrated as an example, but the present invention is not limited to this, and even a frame interline transfer type with a memory area can be used. The invention is applicable.

Further, the forced accumulation control pulse and the transfer pulse are configured to be output from the clock generator 13, and the MPU 1
From 4 onwards, a configuration may be adopted in which a control signal for outputting the forced paving control pulse and transfer pulse is output.

"Effects of the Invention" As is clear from the above explanation, according to the present invention, the charge accumulation time of the imaging means can be controlled according to the brightness of the subject, and the sweeping request means can be turned on in the movie mode. Then, the pulse signal output means outputs a sweep signal every l fields after outputting the read signal, and the charges in the vertical transfer section are swept out in a short time. Therefore, the difference in smear level between movie mode and still mode is eliminated, making it possible to obtain uniform images in both modes, and furthermore, there is no need to adjust the smear level, and even if it is necessary, it can be done easily. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of an image sensor driving device according to the present invention. FIG. 2 is a specific circuit diagram of the drive device around the sweep switch. FIG. 3 is an inversion type driver. 4 is a timing chart of the inversion type driver shown in FIG. 3; FIG. 5 is an operation flowchart of the image sensor driving device shown in FIG. 1; FIG. 6 is a timing chart of each part of the image sensor driving device shown in FIG. 1. 11...COD element (imaging means), 12...driver (pulse signal output means), 13...
・CCD driving clock generator (pulse signal output means), 14...MPU (control means),

Claims (3)

[Claims] (1) Imaging means equipped with a light receiving section that converts incident light from a subject into signal charges and accumulates them, and a vertical transfer section that temporarily holds the signal charges accumulated in this light receiving section; Periodically outputting an accumulation control signal to the imaging means for transferring the signal charge accumulated in the light receiving section to the vertical transfer section, and after outputting the periodic accumulation control signal,
While outputting a readout signal for sequentially reading out the signal charges transferred to the vertical transfer section of the imaging means to the imaging means, when a sweep request signal is input from the outside,
pulse signal output means for outputting a sweep signal to the imaging means at a predetermined time and for a predetermined time to sweep out the charge transferred to the vertical transfer section in a short time; control means for outputting a forced accumulation control signal to be transferred to the pulse signal at an arbitrary timing and a sweep request signal to the pulse signal output means; and a sweep request signal output for outputting the sweep request signal to the pulse signal output means. 1. A driving device for an image sensor, comprising: means. (2) Claim 1 is characterized in that the sweep signal requesting means is constituted by a switch member connected to the control means, and the sweep request signal is output from the control means in response to ON/OFF of the switch member. A driving device for an image sensor. (3) In claim 1, when the sweep request signal is input, the pulse signal output means starts outputting the sweep signal after the end of output of the read signal, and when outputting the next periodic accumulation control signal. 1. A driving device for an image sensor, characterized in that: