JPH0420168B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an improvement to an electric shutter device for a camera;
More specifically, the present invention relates to an improvement in an electric shutter device in which opening of the shutter is started by energization of a shutter opening magnet, and a trigger switch for starting charging of an integral capacitor is operated in conjunction with the opening of the shutter.

The conventional electric shutter device as described above maintains the energization time of the shutter opening magnet at a constant time sufficient for opening the shutter. Therefore, even when the shutter is opened and the trigger switch is activated, the shutter opening magnet continues to be energized, which wastes the power supply battery. Further, at low temperatures or under low voltage, the shutter may not open within the above-mentioned fixed time.

The present invention has been made to solve the above-mentioned problems, and starts the shutter opening by energizing the shutter opening magnet, and responds to a trigger signal generated by a trigger switch that operates in conjunction with the opening of the shutter. In an electric shutter device having a drive circuit that closes the shutter by driving a shutter closing magnet according to a charging voltage of an integral capacitor to be charged, when the trigger signal is input, power to the shutter opening magnet is turned off. There is provided an electric shutter device for a camera, characterized in that a control circuit for controlling the drive circuit is provided.

FIG. 1 is a block circuit diagram of the device according to the invention, FIG.
3 and 3 are main operating time charts of the circuit of FIG. 1 when the trigger switch operates normally and when it does not operate.

In Fig. 1, the light-receiving element P is placed, for example, behind a sub-diaphragm that is linked to the photographic aperture, and outputs a photocurrent for preliminary photometry to the photometry circuit OP before the shutter opens, and adjusts the exposure as the shutter opens. The photometric photocurrent that determines the value is output to the photometric circuit OP. The photometric circuit OP performs impedance conversion on the photocurrent of the light receiving element P, and outputs the amplified photocurrent as necessary as the charging current of the integrating capacitor C. When the transistor T1 is OFF, the integrating capacitor C outputs a charging voltage based on the output photocurrent of the photometric circuit OP to the comparator circuit CP. The comparator circuit CP compares the charging voltage of the integrating capacitor C with the predetermined voltage output by the constant voltage circuit VR, and outputs "0" to the control circuit SC while the charging voltage is lower than the predetermined voltage, so that the charging voltage remains at the predetermined level. When the voltage exceeds the voltage, it is reversed and becomes “1” as the control circuit
Output to SC. The battery check circuit BC consists of the predetermined voltage of the constant voltage circuit VR and the power supply voltage of the power supply battery B.
V _p and detects the state of consumption of the power supply battery B, and outputs a release prohibition signal to the control circuit SC when the battery B is consumed beyond a certain level. Both the power switch S1 and the release switch S2 are switches that are activated by operating the release button, and when the release button is pressed in the first step, the power switch S1 is first activated.
The release switch S2 is turned ON by the subsequent second step of pressing, and when the button is released, the release switch S2 is turned OFF first as the release button is restored, and then the power switch S1 is turned OFF.
Turn off. The trigger switch TG is turned off when the shutter is opened, that is, when the shutter opening magnet α is turned on, and turned on when the shutter is closed or other photographing end operations are performed. The winding switch WE is turned ON when winding the camera, and turned OFF when the shutter is closed or other shooting operations are completed. The switch signal output circuit GC, which includes a gate circuit, has a built-in chattering prevention circuit and waveform shaping circuit, and is used to control winding switches.
Outputs a release signal when WE is ON and release switch S2 is turned ON, and also outputs a trigger switch.
Outputs trigger signal even when TG turns OFF. The frequency divider circuit FD divides the frequency of the clock signal output from the oscillation circuit OS and outputs various time signals to the control circuit SC. The control circuit SC maintains and stops power supply to each circuit based on the various input signals described above, controls ON/OFF of the transistor T1, and turns ON the shutter opening magnet α and closing magnet β via the drive circuit DR. , OFF control, ON/OFF control of the light emitting element L, etc. A shutter (not shown) opens when the aperture magnet α is energized, that is, turned ON, and its opening is held by the energization or ON of the closing magnet β, and when it is turned OFF, it is released from holding and closes. Light emitting element L
displays the subject at low brightness, but it may also display the consumption of the power battery B, or the ON/OFF state of the shutter opening magnet α and the shutter closing magnet β. reset circuit
RS outputs an initial reset pulse when power is supplied, and a system reset pulse when a sequence end signal is input from the control circuit SC to the control circuit SC and frequency divider circuit FD.

It should be noted that each circuit operates as described above only after power is supplied to each circuit, that is, each circuit starts operating as described above after transistor T2 is turned on.
Each circuit enters an operating state when voltage v _p is supplied from power supply battery B to each circuit.

Although the above is a general configuration, the details of the configuration will be further explained with reference to FIGS. 2 and 3.

First, when winding is performed, the winding switch WE is turned on and grounded. If the release button is pushed in and released in this state, the power switch S1 and the release switch S2 are turned on and off as shown in FIGS. 2 and 3. When the power switch S1 is turned on, the base of the transistor T2 is grounded and the transistor T2 is turned on, whereby the power supply voltage v _p is supplied to each circuit, and each circuit enters an operating state. Therefore, the reset circuit RS outputs an initial reset pulse to the control circuit SC and the frequency dividing circuit FD, as shown by S _r in FIGS. 2 and 3. Thereby, the frequency divider circuit FD is controlled by the control circuit SC
A time signal is output to the control circuit SC, and the control circuit SC starts control.

That is, when the power supply voltage v _p is supplied to each circuit by turning on the power switch S1, at the same time, the control circuit SC
In this case, a photometry command signal with a fixed time width is output to the transistor T1, and its base is grounded and the transistor T1 is turned off and timing is started, and a release prohibition signal is not input from the battery check circuit BC. As a result, the switch signal output circuit GC enters a state where it can accept signals.

As mentioned above, during a certain period of time when the transistor T1 is turned off, the photocurrent for preliminary photometry output from the photometry circuit OP charges the integrating capacitor C, and the comparator circuit CP uses the charging voltage of the integrating capacitor C as a constant voltage circuit. When the predetermined voltage of VR is reached, "1" is output, but the control circuit SC determines whether the subject brightness is sufficient depending on whether "1" is input within a predetermined time. , if insufficient, drive circuit
Outputs a low brightness signal to DR and turns on light emitting element L
let This allows the photographer to know if the subject brightness is insufficient.

When the release switch is turned on by pressing the release button further, the winding switch WE is turned on.
When the release switch S2 is turned ON in the state of
The shutter closing magnet β is turned on by applying a voltage to the base of transistor T2, kept on by grounding the base of transistor T2, and outputs a signal to the drive circuit DR to turn on the shutter closing magnet β.

Next, when a predetermined time t ₁ (for example, 10 msec) has elapsed since inputting the above-mentioned release signal, the control circuit SC outputs a signal to the drive circuit DR to turn on the shutter opening magnet α. As a result, the shutter opens, and the opened state is maintained by the shutter closing magnet β, which is turned on. When the shutter opens, the trigger switch TG turns off.
However, the switch signal output circuit GC outputs a trigger signal.

When the control circuit SC receives the above trigger signal, it outputs a signal to the drive circuit DR to turn off the shutter opening magnet α. Therefore, power is saved, and even if the operating force of the shutter opening magnet α decreases due to low temperature or low voltage, the operation of the shutter opening magnet α can be confirmed by a trigger signal within a predetermined period of time, as described later. Since the drive signal for the magnet continues to be output until the magnet is turned on, the magnet can be operated reliably.

In addition, the control circuit SC grounds the base of the transistor T1 again by inputting the trigger signal.
At the same time as turning off, a new time measurement starts. Therefore, when the shutter opens, the photocurrent for determining exposure, which is now output from the photometry circuit OP, charges the integrating capacitor C, and the charging voltage is again input to the comparator circuit CP. When the charging voltage reaches the predetermined voltage from the constant voltage circuit VR, the comparison circuit CP
will output "1" to the control circuit.

When the control circuit SC inputs “1” from the comparator circuit CP within a predetermined time after inputting the trigger signal,
At the same time as starting a new time measurement, a signal is output to the drive circuit DR to turn off the shutter closing magnet β.
let Thereby, the shutter is released from holding the opening and closes.

In the example shown in FIG. 2, the trigger switch TG is turned ON in conjunction with the closing of the shutter, and the winding switch WE is configured to be turned OFF in conjunction with the photographing end operation following the closing of the shutter.

Then, the control circuit SC outputs a sequence end signal to the reset circuit RS after a predetermined time _t2 has elapsed from inputting "1" to the comparator circuit CP until the end of the photographing operation, and resets the sequence end signal to the reset circuit RS. Circuit RS outputs a system set pulse. As a result, the control circuit SC is reset, and the transistor T2, which has already been turned off by the power switch S1, is reset.
The transistor T2 is connected by disconnecting the grounding of the base of the transistor T2.
Turn off. Therefore, the supply of power supply voltage v _p to each circuit is stopped, and the device returns to its initial state before winding.

The above is a case where shooting was performed normally, and the second
The figure shows the operating timing.

In addition, among the sequence operations described above, if the trigger switch TG does not operate, that is, the control circuit SC inputs the release signal from the switch signal output circuit GC, and the shutter closing magnet β and opening magnet α are turned ON. If the shutter does not open even though the shutter is turned on, or if the trigger switch TG does not turn OFF for some other reason, the switch signal output circuit GC does not output a trigger signal. Therefore, the control circuit SC controls the shutter opening magnet α by inputting the signal.
OFF, transistor T1 is not turned OFF, and new time measurement is not started. Therefore, since the integrating capacitor C is not charged and the comparator circuit CP does not output "1", the control circuit SC also determines that the start of a new time measurement due to "1" from the comparator circuit CP is also caused by the shutter closing magnet β. OFF is also not performed. In other words, the control circuit SC continues to measure time after inputting the release signal, and even if the trigger signal is not input, the control circuit SC calculates the predetermined time required for the shutter opening magnet α to be turned ON and for the trigger signal to be input.
As time _t3 progresses, a signal is first output to the drive circuit DR to turn off the shutter opening magnet α, and
Next, the predetermined time after turning on the aperture magnet α
With the passage of t ₄ , the shutter closing magnet β is
Turn it off. This will cause the shutter to close if it is open. The above-mentioned predetermined time _t3 can be set to wait for a slight delay in opening the shutter due to low temperature or low voltage within a range that allows proper exposure, or it can be set to be the same as the predetermined time _t4 .
The control circuit SC that turned off the shutter opening magnet β sends the sequence end signal to the reset circuit RS.
output to each circuit, and stop the power supply to each circuit.
If the shutter has been opened, the device will
It returns to the initial state before winding, and if the shutter has not been opened, it returns to the state where only winding was performed. Therefore, even if the trigger switch is not activated, the power supply battery will not be wasted unnecessarily.

FIG. 3 shows the above-mentioned operation timing when the trigger switch is not activated.

In addition, if the release is operated without winding, the winding switch WE remains OFF even if the release switch S2 is ON, so the switch signal output circuit GC transfers the release signal to the control circuit.
There is no output to SC, therefore, shutter closing magnet β and opening magnet α are not turned on.
Since the release sequence is not performed, no sequence end signal is output, and the base of transistor T2 is not grounded for holding, so power supply is stopped when power switch S1 is turned off. Returns to the initial state of unwinding.

Furthermore, when the release prohibition signal is input from the battery check circuit BC, the control circuit SC does not accept the signal from the switch signal output circuit GC, and therefore the release sequence is not performed as in the case where winding is not performed. .

Although the configuration of the illustrated apparatus has been described in detail in relation to its operation, it goes without saying that the present invention is not limited to the illustrated example.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of the device according to the invention, FIG.
3 and 3 are main operating time charts of the circuit of FIG. 1 when the trigger switch operates normally and when it does not operate. P...Photodetector, OP...Photometering circuit, SC...Control circuit, T1, T2...Transistor, C...Integrating capacitor, CP...Comparison circuit, VR...Constant voltage circuit, BC...Battery check circuit , B...power supply battery, _vp ...power supply voltage, S1...power switch, S2...release switch, TG...trigger switch, WE...winding switch, GC...switch signal output circuit, FD...minute Circuit, OS...
Transmission circuit, DR...Drive circuit, α...Shutter opening magnet, β...Shutter closing magnet,
L...Light emitting element, RS...Reset circuit, S _r ...
Reset signal.

Claims (1)

[Claims] 1 Starts the shutter opening by energizing the shutter opening magnet, and drives the shutter closing magnet in accordance with the charging voltage of the integral capacitor that is charged in response to a trigger signal generated by a trigger switch activated in conjunction with the opening of the shutter. In an electric shutter device having a drive circuit for closing the shutter, when the trigger signal is input, the shutter opening magnet is not energized.
An electric shutter device for a camera, comprising a control circuit that controls the drive circuit to turn it off.