JPS5883476A - Image pickup device - Google Patents

Abstract

PURPOSE:To keep the phase relation constant to a reference synchronizing signal, by comparing an average DC level of a video signal pickup up based on the reference synchronizing signal with a saw tooth wave signal formed from the reference synchronizing signal, and determining the shutter opening time. CONSTITUTION:A light obtained from an electronic shutter 8 is irradiated to a photodetector 21 and given to a transfer section 22 with a reference synchronizing signal from a synchronizing signal generating circuit 23, and to a recording processing circuit 25 via a video processing circuit 24 with the signal from the circuit 23. A vertical synchronizing signal VD being a reference is applied to a control circuit 26 controlling the processing circuits 24 and 25. A picked-up video signal from a CCD chip 9 is given to the circuit 26, where an average DC level is picked up and the level is applied to a voltage comparator together with a saw tooth wave signal formed based on the signal VD for comparison and the opening time of a shutter 8 can be controlled with the output of voltage comparison.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging device that captures an image of a subject with an image sensor through an optical system and reads it out as an electrical video signal, and particularly relates to a small electronic device that records the video signal on a rotating magnetic sheet. The present invention relates to an imaging device suitable for use in a camera.

For example, CCD (Charge Coupled
Device) A small electronic camera that records still image video signals from an imaging device such as an image sensor on a recording medium such as a small rotating magnetic sheet has various functions similar to those of general film cameras, such as aperture priority shutter. Automatic speed control function, strobe shooting function, continuous shooting function, multiple exposure function, etc. are required, but reading out video signals from the image sensor such as the CCD image sensor is
Since the timing is sequentially based on a certain reference synchronization signal, the timing of opening/closing the shirt, the timing of strobe light emission, the timing of recording on the recording medium, etc.
It is necessary to maintain a constant phase relationship with respect to the reference synchronization signal.

In view of these circumstances, the present invention makes it possible to control the shutter opening time according to the amount of exposure, such as when automatically controlling the shutter speed with aperture priority, and to adjust the shutter opening/closing timing and the above-mentioned criteria. The object of the present invention is to provide an imaging device that can maintain a constant phase relationship with a synchronization signal.

That is, the feature of the imaging device according to the present invention is that a video signal captured based on a reference synchronization signal is read out from an imaging device disposed behind a shutter, an average DC level of this video signal is detected, The purpose is to compare a sawtooth wave signal, which is a reference signal for time determination and is formed from the reference synchronization signal, with the average DC level, and determine the opening time of the shutter based on the comparison output.

Preferred embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 1 shows a small electronic camera 1 in which an imaging device according to the present invention is used. FIG. 2 is a perspective view schematically showing the entire structure. The external shape of this small electronic camera 1 is similar to that of a conventional single-lens reflex camera, and a cylindrical lens portion 3 is attached and fixed to the front side of a rectangular parallelepiped-shaped housing 2. A removable battery bag 4 is provided on the side of the housing 2, and a rechargeable battery or a dry cell battery 5 is housed in the battery pack 4.The subject is the lens 6 of the lens unit 3 and the mirror 7. CCf) (Char
ge Coupled Devlce) is imaged onto the chip 9. Here, in the mirror 7, most of the incident light is reflected, and the light is reflected by another mirror 10 and sent to the finder window section 11. The electronic shutter 8 uses, for example, a liquid crystal or the like, and has a light transmittance that changes according to an electrical control signal. The CCD chip 9 has a photoelectric conversion semiconductor cell (photocell), for example, 490 x 570 in length and width.
By sequentially scanning these cells, a video signal conforming to a general television signal is output. This output video signal is recorded on a magnetic recording medium (rotating magnetic sheet) housed in the magnetic seat back 12 so as to form concentric tracks.

This recording is performed in accordance with the pressing operation of the release button (or shutter button) 13 while maintaining a constant synchronous relationship with a reference synchronization signal, which will be described later. At this time, the rotating magnetic sheet in the magnetic sheet pack 12 must also be rotationally driven by the motor 14 so as to maintain a constant synchronization relationship with the reference synchronization signal. For this reason, the release button 13 is configured so that it can be mechanically operated in two steps, and when the first step is a suppression operation, the rotation of the motor 14 is started and the motor 14 is kept on standby in the state in which the synchronization relationship is maintained. During the suppression operation, a video signal from the CCD chip 9 is recorded on the rotating magnetic sheet. Next, the mode selection switch 15 is
For example, it is a sliding four-stage switch that can be selectively set to one of the following modes: off mode, single-shot mode, continuous shooting mode, and multiple exposure mode.

Furthermore, although it is not shown in FIG. 1, numerical values in the continuous shooting mode and multiple exposure mode (the repetition period of continuous shooting and the number of multiple exposures) are displayed at a predetermined position on the back surface of the housing 2, for example, in the upper right position. A setting changeover switch is provided, for example, it is a 4-stage changeover type, with four types of continuous shooting cycles: 2 seconds, 1 second, 1/2 seconds, and 1/4 seconds, and the number of multiple exposures is 2 times. Four types can be selected: 4 times, 8 times, and 16 times. Further, a piezoelectric buzzer 16 for various warnings, a self-timer lever 17, an accessory shoe 18 for attaching a strobe light, etc., which will be described later, are provided as necessary.

Next, the schematic configuration of the internal circuit will be explained with reference to FIG. 2.

In this FIG.
The light from the subject obtained through the light receiving section 21 is focused on the light receiving section 21 . This CCD chip 9 is driven by a reference synchronization signal from a synchronization signal generation circuit 23, and this reference synchronization signal includes a horizontal synchronization signal HD and a vertical synchronization signal VD, like a normal television video signal. be. The image information signal photoelectrically converted by the light receiving unit 21 is sent to the transfer unit 22 during the vertical blanking period, for example.
From the transfer section 22, the video signals are timed by the HD and VD synchronization signals and are sequentially transferred to the video processing circuit section 24. Light receiving section 21 in this case
Signal transfer from the transfer unit 22 to the video processing circuit 24 and from the transfer unit 22 to the video processing circuit 24 are sequentially performed by a transfer lock signal tcK from the synchronization signal generation circuit 23.

Next, the video processing circuit section 24 outputs, for example, the luminance signal Y1 and the color difference signals R-Y and B-Y, and sends them to the recording processing circuit section 25. These processing circuit units 24 and 25 are
6 by the control signal from the control circuit section (controller) 26.
controlled. The control circuit section 26 is supplied with the vertical synchronization signal VD that serves as the reference, and according to this signal VD and the release signal from the release switch 27 (signal caused by the second stage suppression operation of the release button 13). ,
The ON operation of the recording gate switch 28 of the recording processing circuit section 25 is controlled. This switch 28 is the autumn equinox in the image.
That is, it is for sending a video signal of -vertical period (17 intervals) to the recording head 29, and this picture-autumn equinox video signal is recorded as concentric recording tracks on the rotating magnetic sheet 30. In addition, in order to sequentially obtain a large number of temporally continuous images for each VD, rather than a still image such as the above-mentioned autumnal equinox image, the signal at the position before the switch 28 of the recording processing circuit section 25 is converted into a movie. Output terminal 31
Just take it out.

Next, the servo circuit section 40 of the motor 14 that rotationally drives the rotating magnetic sheet 30 will be explained. The rotating shaft of the motor 14 (or the hub portion of the rotary air rupture sheet 30, etc.) has a
A pulse generator 32 for detecting the rotational position and a frequency generator 33 for detecting the rotational speed are provided. From the frequency generator 33, a signal with a frequency proportional to the rotational speed of the motor 14 and the rotating magnetic sheet 30 is generated.
The signal is sent to a frequency-voltage converter (f-V converter) 41 of the servo circuit section 40, and sent to a voltage comparator 42 as a voltage signal corresponding to the rotational speed.

This voltage comparator 42 is supplied with a reference voltage corresponding to a rotational speed (rotation speed) of, for example, 3600 rpm from a reference voltage source 43, and this reference voltage and the output voltage from the fV converter 41 are The error amount is sent as a speed error signal to the motor drive amplifier 45 via the adder 44 and fed back to the motor 14. Particularly, the pulse generator 32 detects a constant rotational angle position every rotation of the rotating magnetic sheet 30 and generates a pulse.
Although it may be configured to generate two or more pulses per rotation, in order to simplify the explanation, it is assumed that one pulse is generated per rotation. This rotational angle position detection pulse (or rotational phase detection pulse) is sent to the phase comparator 46.
, the phase is compared with the reference vertical synchronizing signal VD from the synchronizing signal generating circuit 23, and this phase error signal is fed back to the motor 14 via an adder 44 and a motor drive amplifier 45.

Next, a specific configuration of the control circuit section 26 and an example of its operation will be explained with reference to FIGS. 3 and 4. In FIG. 3, the output pulse PG from the detection head 35 of the pulse generator 32 is As shown in FIG. 4a, the cycle gradually increases as the rotational speed increases over time from the start of driving the motor 14 in response to the first operation of the release button 13. Appears to be shorter. This output pulse PG is sent to the delay circuit 52 via the amplifier 51 and delayed by a time τ, and is converted into a pulse having a pulse width τ3 by the multi-purpose circuit 53. This pulse is inverted by the inverter 54, becomes a reset signal as shown in FIG. 4, and is sent to the reset terminal of the D-type flip-flop 55. The reference vertical synchronizing signal VD as shown in FIG. 4C is sent to the clock input terminal of the D-type flip-flop 55, and the 10B power supply terminal is connected to the data input terminal. Therefore, only when the vertical synchronizing signal VD is input during the reset signal SugaL (low level), the data of the 10B power supply voltage is
H (high level) appears at the output terminal Q of the D-type flip 70 knob 55, and this output is as shown in FIG. 4d. In FIG. 4, the rotational speed and phase of the motor 14 are locked at time t1 by the operation of the servo circuit section 40 described above, and the servo is controlled so that the PG pulse maintains a constant phase relationship with the VD pulse. Since the output terminal Q of the p-type flip-flop 55 is controlled after this time t1,
A pulse P synchronized with the above-mentioned VD is output from , and this pulse output is sent to the counter circuit 56 .

This counter circuit 56 uses, for example, a hexadecimal counter, and at time t2 in FIG. 4 when six pulses P are input, a carry pulse is outputted to the R-8 flip-flop 5.
It is sent to the set input terminal of 7.

Further, the pulse P shown in FIG. The output is inverted by an inverter 59 to become a reset signal as shown in FIG. Here, the monomulti circuit 58 is of the so-called IJ i, IJ null type, and if it is once triggered and then triggered again within the time of the pulse width (for example, 1°5V), the An attempt is made to output a pulse with the above pulse width from the time it is triggered, and while the pulse is continuously triggered at a cycle shorter than this pulse width, it does not return to the initial state (for example, °L"). Therefore, the fourth As shown in FIG. d, while being sequentially triggered by periodic pulses P, the output from the inverter 59 (FIG. 4 e) and the counter circuit 56 check whether the servo of the motor 14 is locked or not. It is determined that the servo lock is stable only when six pulses P in Fig. 4d appear consecutively like P!~P6, and the input time of the pulse P6 is determined as follows. At t2,
A carry pulse as shown in FIG. 4f is output from the counter circuit 56, and the R-8 flip-flop 57 is set. The Q output from R-8 flip-flop 57 is
As shown in Fig. g, the temperature becomes °H° at the above-mentioned time t2. This output g is a servo lock state judgment information signal,
The signal is sent to an amplifier 60 and drives a ready display LED (light emitting diode) 61 to light up. This LED61 is
For example, it is placed within the field of view of the finder.

Next, the output from the switch 27 is turned on in response to the second operation of the release button 13.
As shown in the figure, it is input at a timing unrelated to the synchronizing signal VD, PG pulse, etc.

This second stage release operation signal is transmitted to the mono multi circuit 62.
The signals are waveform-shaped and sent via an OR circuit 63 to AND gates 64 and 65, respectively.

These AND gates 64 and 65 perform complementary conduction and cutoff operations (operation in which one conducts and the other shuts off) in response to a gate control signal from an AND circuit 66.
Do the following. The AND gate 64 becomes conductive when all of the conditions necessary for complete recording of the video signal described above are satisfied, and the other AND gate 65 becomes conductive when at least one of the conditions described above is satisfied. It becomes conductive when it is not satisfied. For example, to determine the servo lock state of the motor, the Q output from the R-8 flip 70 knob 57 as shown in FIG. , this Q output g is sent as a gate control signal to an AND gate 64 as it is, and is inverted by an inverter 67 and sent to an AND gate 65, respectively.

Therefore, before time t1 in FIG. 4, the Q output g is Lr CI'/Pl! 21y, since the tlIb is cut, the AND gate 64 is in the cut-off state and the -AND gate 65 is in the conductive state, and after time t2, the Q output g and the output of the AND circuit 66 are "Ho". The AND gate 64 is in a conductive state, and the AND gate 65 is in a cut-off state.Here, at an arbitrary time to before the above-mentioned time t2, the slitch 27 for the second stage release operation is turned on, and the signal of the fourth figure is turned on. When it becomes Ho, this release operation signal is sent to the amplifier 68 via the AND gate 65, drives the piezoelectric buzzer 16 mentioned above, and lights up the LED 69 indicating the unrecordable angle. This LE
D69 is arranged, for example, within the field of view of the finder.

Next, when the switch 27 is turned on at an arbitrary time t3 after the time t2 and the signal shown in the fourth diagram becomes H, this signal is passed through the AND gate 64 to the clock of the flip-flop 71. sent to the input terminal. The Q output of this J-flip-flop 71 is sent to a series-connected circuit of three J-flip-flops 72, 73, and 74.

These three J- have flip-flops 12, 13.7
The PG pulse shown in FIG. 4a from the pulse generator 32 is supplied to each clock input terminal of 1.4. This PG pulse is sequentially delayed by one period and sent to the next stage. Here, the reset terminal of the flip-flop 71 at J- of the first stage is connected to the Q output of the flip-flop 72 at J- of the second stage.

As shown in FIG. 4J, the Q output from the flip-flop 72 to J- in the second stage of G is output from the first PG pulse input time t4 after the above-mentioned time ts. , only until the next (second) PG pulse input time t6 is a pulse of °H°. The Q output from the flip-flop 73 at the next third stage J- is the signal shown in FIG. Therefore, as shown in FIG. 4, the signal is delayed by one period and appears. While the Q output from the flip-flop 73 becomes "H" in the third stage J- (from time t6 to t6), the video signal read out from the transfer section 22 of the CCD chip 9 is The video signal recording magnetic head 294 is sent to record and form one concentric recording track on the rotating magnetic sheet 30.

This recorded video signal is transmitted to the light receiving section 21 of the CCD chip 9 before time t5 (from time t4 to t
This is the signal of the image received during the period up to 5). Next, the Q output of the flip-flop 74 at J- in the fourth stage is converted into a signal with a constant pulse width as shown in FIG. sent to. The output from this amplifier 76 causes the video signal recording magnetic head 29 to be moved onto the rotating magnetic sheet 30.
The coil 77 of the head sending plunger for moving the magnetic head 29 in the radial direction is driven, and the magnetic head 29 is sent by one track in the radial direction.

By the way, the AND circuit 78 and the NOR circuit (N
The AND circuit 78 and the NOR circuit 79 are supplied with a condition determination signal obtained by determining the various conditions necessary for complete magnetic recording of the captured video signal. The output from the AND circuit 66 is sent to the AND circuit 78. For example, the track number after the head feed is the maximum recordable track number (for example, 50
The track end detection signal becomes °L° when the magnetic head 29 reaches the position of the next recordable track when the magnetic sheet pack 12 on which several tracks have already been recorded is mounted. °
A track coincidence detection signal that becomes "H", an accidental erasure prevention signal that becomes "L" when the accidental erasure prevention claw of the magnetic sheet pack 12 is detected and recording is prohibited, and a power source for the battery pack 4, etc. A possible example is a battery check signal that becomes °L° when recording is difficult due to voltage drop, etc. All of these input signals to the AND circuit T8 are signals that become "Ho" when recording is possible. . Furthermore, the input signal to the NOR circuit 79 is as described below.
This is a signal that becomes °H° when so-called underexposure or overexposure (overexposure) is detected, and both are in the "Lo" state when recording is possible. Therefore, the outputs from these AND circuits 78 and NOR circuits 79 are , if any one of the above conditions for complete recording is not satisfied, it becomes °L°, and the output of the AND circuit 66 becomes °L°.
Therefore, the AND gate 64 is cut off, the AND gate 65 is turned on, and when the second stage release operation switch 27 is turned on, the buzzer 16 sounds and the LFliD 69 is lit.

Next, the timing of major operations in response to the second-stage operation of the release button 13 will be explained with reference to FIG. 5.

First, FIG. 5 shows the second operation of the release button 13, that is, the ON operation of the switch 27.
This turning-on time tto is the time when the PG is turned on as shown in FIG. 5B.
It appears independently of the timing of the pulse (equal to FIG. 4a) and the reference vertical synchronization signal VD shown in FIG. 5C (equal to FIG. 4C). If the PG pulse and the VD do not satisfy a predetermined phase relationship (the servo lock is not applied), then at time t in FIG.
An error output (FIG. 4i) as shown in the operation from o appears, and the buzzer warning and recording failure display as described above are performed. Now, FIGS. 5B and 5C show the above-mentioned servo lock state in which the PG pulse and the VD pulse satisfy a predetermined phase relationship, and the period of these pulses is 1/60 seconds. There is. At this time, when the switch 2T is turned on at the time t1o, the Q output of the flip-flop 72 changes from the PG pulse input time (pulse fall time in FIG. 5B) bt to the J- of the second stage. rises as shown in the fifth diagram and falls at the next PG pulse input time t1m 1760 seconds later. This pulse signal in Figure 5 is equal to that in Figure 4j. Next, the Q output from the flip-flop 73 at the third stage J- is as shown in FIG. 5E.
The signal shown in the fifth diagram appears delayed by IV (1/60 second), rises at east time 112, and falls at time to. This figure 5 E
The pulse signal shown in FIG. 4 is the same as that shown in FIG. , as shown in FIG.
', and the shutter opening time τS changes depending on the amount of light.
Later “L.

By repeatedly performing the following actions, these °
H" and 'L" correspond to opening and closing of the shutter, respectively.

Here, the image information signal of the light receiving section 21 of the CCD chip 9 is approximately the synchronization pulse interval τ of the vertical synchronization signal shown in FIG. 5C.
During V, it is transferred to the transfer unit 22, and from this transfer unit 22, a video signal for l fields, which is similar to a general television video signal, is read out in the time of one vertical scanning period (lV = l/60 seconds). . Therefore, the above time tti,
The image information signal received by the light receiving unit 21 during the shutter release time of 18 out of tL2 is transferred between time t12 and tH shown in FIG. 5E. The information is read out from the section 22, sent to the above-mentioned controller 29, and recorded.Also, when using a strobe,
The pulse shown in Fig. 5 (pulse shown in Fig. 4 j) is delayed by τD in the slow-to-ground circuit 81 shown in Fig. 3, and is sent to the monomulti circuit 83 via the AND circuit 82, thereby producing the pulse shown in Fig. 5 G. A short-time strobe pulse as shown is generated, a strobe light emission driving transistor 84 is turned on, and a strobe driving signal is outputted from an output terminal 85. Note that a charge-up information signal that becomes "H" when charging of the strobe charger is completed is input to the other terminal 86 of the AND circuit 82. Next, in the multiple exposure mode, a shutter release signal with a pulse width of 1/2000 seconds, for example, is generated at time tl! as shown in FIG. 5 H4. , t11 (particularly from the rise time of VD to time 111), for example, 4
are displayed and sent to the electronic shutter 8. Sorry,
Q from the flip-flop 72 to J- in the '2nd stage above.
The output (FIG. 5, FIG. 4J) is used as a gate signal for the multiple exposure pulse of FIG. 5H.

Next, in the continuous shooting mode, the switch 91 in FIG.
is turned on, and the continuous shooting switching signal from the circuit section after oscillation -92 is supplied to the OR circuit 63 via the switch 91. That is, when the switch 27 for the second stage release operation is turned on, this signal is sent to the oscillator 92, and the oscillator 92 outputs pulses of, for example, 4 Hz (4 pulses per second). This pulse consists of three stages of l
/2 frequency divider (or binary counter) 93,94°95
These oscillators 92, frequency dividers 9
The four outputs from 3, 94, and 95 are sent to respective switching terminals of a four-contact type switching selection switch 96. This changeover selection switch 96 is used to set the above-mentioned numerical value, that is, to set the repetition rate of continuous shooting in continuous shooting mode, and is used to set the repetition rate of continuous shooting in the continuous shooting mode.
and 2 seconds, the repetition period can be selected. The output from the changeover selection switch 96 is sent to the OR circuit 63 via the switch 91, and the same operation as the above-mentioned negative to negative shooting is sequentially repeated at each of the selected repetition periods.

Next, the multiple exposure mode and shutter opening time control operations described above will be further explained with reference to FIGS. 6 to 8.

FIG. 6 is a block circuit diagram schematically showing an example of a circuit configuration for driving and controlling the electronic shutter 8;
The transmittance of the electronic shutter 8 changes in accordance with the output from the output terminal 100, and is controlled in a binary manner, for example, between a light transmitting state and a light blocking state.

First, as a circuit unit for multiple exposure mode operation, the oscillator 101 oscillates at about 1 kHz, for example, and oscillates at about 16 kHz within the l vertical travel period (IV period='l/60 seconds).
It is designed so that it can output 100 pulses. The output from this oscillator 10゛1 is output from a frequency division circuit or frequency division m
to2, and the pulse signal of approximately 1kHz is 1/
Three outputs of 2, 1/4, and 1/8 are sent to three switching terminals of the selection switch 103, respectively.

This selection switch 104 has four switching terminals, and the output pulse from the oscillator 101 is supplied to the remaining one switching terminal. Therefore, by switching and selecting the selection switch 1°3, one of 16, 8, 4, and 2 pulse outputs can be obtained during the IV period, and this pulse output is applied to the monomulti circuit 1.
For example, 1/2000 seconds (Q, 5
m5ec) and is sent to the OR circuit 106 via the switch 105. This switch 105 acts as a gate and is
Q output of the flip-flop 72 (Fig. 4 j1 Fig. 5 D
) and the multiple exposure mode selection signal from the AND circuit 107. The output from the OR circuit 106 is sent to the output terminal 100 via an amplifier 108 for driving an electronic shutter.

Next, the shirt opening/closing control circuit section 110 includes the CCD
The imaging video signal from the chip 9 is supplied via the input terminal 111, and the vertical synchronization signal VD is supplied to the input terminal 1.
12. An example of an integrated structure of this shirt shirt opening/closing control circuit section 110 is shown in FIG.

In FIG. 7, the imaging video signal supplied to the input terminal 111 is amplified by transistors 121 and 122, and then sent to a clamp circuit 124 via a capacitor 123.
For example, the pedestal level is clamped to a certain level. This pedestal clamped video signal is sent to the base of transistor 125. The emitter output of this transistor 125 is connected to the diode 12
6 and integrated by an integrating circuit 127, and an average DC level of the video signal is taken out by an active low-pass filter 128 and supplied to a non-inverting input terminal of a differential amplifier 129 serving as a voltage comparator. Here, the average DC level from the active low-pass filter 128 is a level corresponding (proportional) to the brightness of the image of the human video signal. Next, the reference vertical synchronization signal VD supplied to the input terminal 112 appears, for example, as shown in FIG. Outputs a sawtooth wave signal like this. This sawtooth wave signal is a reference signal for determining the shutter opening time, and the differential amplifier 129 serving as the voltage comparator (1)
is supplied to the inverting input terminal of Here, if the average DC level from the active low-pass filter 128 appears as the level LDC shown in FIG.
9 to output terminal 1 via transistors 132 and 133.
The output sent to 13 has a pulse width τ, as shown in FIG. 8C.
It appears as a pulse of S. Here, the level LDC shown in FIG. 8 is l when the image of the input video signal is bright.
On the other hand, when the image is dark, the level LDC increases and the pulse width τS becomes longer. The output signal from this output terminal 113 is sent to the OR circuit 106 in FIG.

By the way, when the so-called underexposure state occurs and the level LDC shown in FIG. 8 rises beyond the peak level of the sawtooth wave signal, the output from the output terminal 113 becomes as shown in FIG. 8 d. It is always °H°. At this time, the output from the output terminal 113 is supplied to the data input terminal of the D-type flip-flop 141 in FIG. By detecting and taking out from the Q output terminal of the D-type flip 70 knob 141, it is possible to obtain an underexposure detection signal which becomes °H° only when the upper part is underexposed. Here, the sawtooth wave forming circuit 131 in FIG. 7 and the circuits before and after it, the differential amplifier 129, the transistor 132
, 133, the waveform in Figure 8C appears slightly delayed, and the rise of the pulse in Figure 8C is slightly slower than the rise of the VD pulse in Figure 8A. appears later. Therefore, while the shutter is opened and closed within the range that does not lead to the above-mentioned underexposure,
from the D-type flip-flop '141.

The output is L, and it is °H only when underexposure.

becomes. Based on the Q output from the D-type flip-flop 141, the amplifier 142 drives the LBD 143 for indicating underexposure.

Next, a so-called overexposure condition occurs, and the average DC level LDC shown in FIG.
When the pulse width τ5 in Figure C becomes a certain value, for example, l/2000 seconds (0.5N(6)) or less, D in Figure 6
An overexposure detection signal is output from the type flip-flop 146. This means that the output from the above output terminal 113 is
A delayed VD pulse as shown in FIG. , the input data is taken in at the rising edge of this delayed VD pulse, and the inverted signal is sent to the D-type flip-flop 146.
It is taken out from the Q output terminal of. Here, delay circuit 1
The delay time due to 45 is approximately 1/2000 seconds, and to be more precise, the delay time is approximately 1/2000 seconds, and more precisely, the delay time is between the rise of the reference VD pulse in Figure 8a and Figure 8C.
This is the sum of the time lag between the rise of the shutter opening and closing pulses and the above 1/2000 second. Therefore, the Q output of the D-type flip-flop 146 becomes °H° only when overexposure occurs and the shutter opening time τS becomes 1/2000 seconds or less, and this overexposure detection signal is transmitted to the amplifier 147.
is sent to the LBDl 48 via the overexposure display.

Furthermore, these D-type flip-flops 141°
They are each sent to the two-person Kanoa (NOR) circuit 79 in the figure.
The output from this NOR circuit 79 is sent to the AND circuit 66.

In addition, in the multiple exposure mode, the input terminal, terminal 13 in FIG.
5 is supplied with, for example, a 10B power supply voltage, and this voltage is sent to the inverting input terminal of the differential amplifier 129 via the diode 136. Therefore, the shutter opening/closing pulse in FIG. ), and switch 1 in Figure 6
The opening and closing of the electronic shutter 8 is controlled by the output from 05. At this time, although not shown, the overexposure detection signal is cut off midway and is of course not supplied to the NOR circuit 79 in FIG. 3.

Of the operations of each part of the electronic camera described above, the system control operation is performed using a microcomputer device, for example, and will be schematically explained according to the entire operation sequence from power-on to video signal recording.
Ru.

First, when the main power of the small electronic camera 1 shown in FIG. 1 is turned on, initial settings and resets of various functional sections are performed. The main power may be turned on simultaneously when a position other than the off mode of the mode selection switch 15 is selected, but a separate main power switch may be provided on the back surface of the housing 2 or the like. Then, the erroneous erasure prevention claw of the magnetic sheet pack 12 is checked, and it is detected that the value of the shot number counter of the magnetic sheet pack 12 matches the track number on which the video signal recording magnetic head is located. If not, move the magnetic head in the radial direction until they match. Assuming that the maximum number of images to be captured in the magnetic sheet pack 12 is 50, a track end detection signal is output when the magnetic head reaches the 51st track position. If any one of these three conditions is not satisfied, for example, when the release button 13 is operated, a warning is given by the piezoelectric buzzer 16, and an LED or the like is lit in the field of view of the finder.

Next, for example, a battery check button (not shown), a self-timer lever 17, and a release button 1
The three operation states of the second stage operation in step 3 are sequentially and repeatedly detected, and if an operation has been performed, the process jumps to the respective sequence, and if none of the operations have been performed, the above detection is repeated.

First, in the battery check sequence, the voltage of a power source such as a dry cell battery 5 is detected, and if the voltage drops and there is a power shortage, a warning is issued using a piezoelectric buzzer 16 or the like.

Next, in the self-timer sequence, the process jumps to the release sequence approximately 10 seconds after the self-timer lever 11 is pressed. At this time, for example, for the first 7 seconds, a slow intermittent buzzer sound and a blinking LED will continue.
For the next 2 seconds, you will hear a fast intermittent buzzer and the LED will flash.1. During the last second, the buzzer continues to sound continuously and the LED remains lit. Then continue to the release sequence. During this time, servo lock detection is performed at any time.

Next, in the release sequence, the photographing mode corresponding to the setting operation position of the mode selection switch 15 is checked, and each mode is executed. First, when the single-shot or continuous shooting mode is selected, the shutter release prohibition state is canceled and the electronic shutter drive system is activated. Synchronize with the rising edge of VD to check whether it is a regular field.

If the fields are different, wait until the next field. Here, if the dedicated strobe is attached and fully charged, the electronic shutter 8 is opened and the VD
For example, 1.3 ms after the rise of the strobe light pulse (see FIG. 5G) is output. If the strobe is not on or if it is not fully charged, normal shooting will occur, and if the exposure is appropriate, the camera will jump to the recording sequence. If the exposure amount is not appropriate, a buzzer sounds to warn you, no recording is made, and the process jumps to the operation status detection sequence described above.

Next, when the lower multiple exposure mode is selected, a signal is output to open the electronic shutter for 1/2000 seconds at appropriate intervals a number of times according to the number of times setting SW within the period lv. Then jump to the recording sequence.

Next, in the recording sequence, the video signal during the IV period from the falling edge of the PG signal to the next falling edge is recorded. As explained above in conjunction with Fig.
The difference is that the field that is exposed to light is different from the field that is recorded on the magnetic sheet. This is because in the COD image sensor, the light receiving section and the transfer section are separated, and the received light signal is sent to the transfer section during the vertical blanking period. After the magnetic head finishes recording, the head is advanced by one track.

After confirming that the second stage operation of the release button 13 has been completed, the process jumps to the track end detection sequence described above.

In the case of continuous shooting mode, after recording, the sequence of the single shot and continuous shooting mode is executed again after waiting for the time corresponding to the repeat cycle setting switch, and the second step operation of the release button 13 is performed. Repeat until finished.

Other subprograms include, for example, a servo lock detection sequence and an exposure display sequence.

In the servo lock detection sequence, if the time difference between the PG rising edge and the VD rising edge is within a predetermined range, the R
The EADY lamp, that is, the LED 61 in FIG. 3 lights up. When the lock is released, the lamp goes out.

Next, in the exposure display sequence, the electronic shutter 8
The opening/closing control signal from the drive control system is detected, and if the shutter is always open, underexposure is displayed, and if the shutter opening time is 1/2000 seconds or less, overexposure is displayed.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, as the image sensor, in addition to the CCD image sensor, an MO8 type image sensor and various other solid-state image sensors or image pickup tubes can be used. In addition, the video signal for one image to be recorded is not only for ■field, but also for
One frame (=°2 fields) may be used.

Also, a mechanical shutter may be used instead of the electronic shutter. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing main parts of the overall shape of a small electronic camera 1 to which an imaging device according to the present invention is applied;
2 is a block circuit diagram showing a schematic configuration of the internal circuit, FIG. 3 is a block circuit diagram showing an example of the main part of the control circuit section 26 in FIG. 2, and FIG. 4 is a block circuit diagram showing the main part of the control circuit section 26 in FIG. 5 is a time chart for explaining the operation of each sub-image mode in the servo lock state. FIG. 6 is a block circuit diagram showing an example of the electronic shutter drive control system. Fig. 7 is a circuit diagram showing a specific example of the shutter opening/closing control circuit section 110 of the niece Fig. 6, and the first... small electronic camera 8... electronic shutter 9... CCD chip. 12...Magnetic seat back 13...Release button 14I...Motor 15...Mode selection switch 23...Synchronization signal generation main circuit 26 ... Control circuit section 29 ... Magnetic head 30 ... Rotating magnetic sheet 40 ... Servo circuit section 110 ... Shirt opening/closing control circuit section 111...
. . . Imaging video signal input terminal 112 . . . Reference vertical synchronization signal input terminal 113 . . . Shirt open/close control signal output terminal 127 . . . Integrating circuit 128 .・Active low-pass filter 129...
... Differential amplifier 131 for voltage comparison ... Sawtooth wave forming circuit

Claims (1)

[Claims] A video signal imaged based on a reference synchronization signal is read out from an image sensor disposed behind the shirt and evening, the average DC level of this video signal is detected, and a sawtooth shape formed from the reference synchronization signal is read out. An imaging device characterized in that the wave signal and the average DC level are compared, and the opening time of the shirt is determined based on the comparison output.