JPH0326803B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention eliminates wasteful power consumption, and
The present invention relates to a control circuit for a programmable electric shutter linked to a light receiving unit, which stabilizes exposure control operation.

In an electromagnetic activation control circuit, the time for supplying power to the electromagnet is generally set to a predetermined constant time with some margin so that the actuating mechanism can reliably complete its work.

Therefore, supplying power until the end of a certain period of time after the work is completed results in wasted power consumption.

It is also possible to stop the power supply to the electromagnet using the completion of the work of the operating mechanism as a signal, but in order to obtain this signal, a new element (mechanical switch,
photo sensors, etc.), which had the disadvantage of increasing costs.

Therefore, the first object of the present invention is to set the electric circuit system to an exposure warning mode when the light-receiving element is exposed to field light in a stationary state, and when the shutter mechanism is activated, the light-receiving element is exposed to field light. Motoko is
The field light is temporarily blocked, and as the shutter blades are opened, they are exposed again one after another, and the electric circuit system is switched to exposure control mode, which is activated by supplying power to the electromagnet. In a light-receiving unit-linked programmable electric shutter controlled by excitation operation, the start-up operation of the shutter mechanism includes:
When the power supply to the electromagnet is completed within a certain period of time, the power supply is stopped by an output change signal of the light-receiving element circuit when the light-receiving element is once blocked from field light upon activation, To provide a control circuit that does not add any new elements, is contactless, and eliminates wasteful power consumption.

Furthermore, in a programmable electric shutter linked to a light receiving section, when the activation of the shutter mechanism and the closing of the shutter blades are controlled by a single electromagnet, the operation is performed as follows.

(i) A large current is applied to the electromagnet for a certain period of time in response to a start signal to attract the iron lever, and the attracted action of the iron lever activates the shutter mechanism.

(ii) After the above-mentioned certain period of time has elapsed, the power supply to the electromagnet is suppressed to a small current to maintain the attracted state of the iron piece lever and prevent the movement of the closing drive member of the shutter blade.

(iii) The exposure control output signal completely stops the power supply to the electromagnet, and the movement of the closing drive member is released by the separation movement of the iron piece lever to close the shutter blade.

The above conventional example had the following drawbacks.

(i) If we assume that the certain period of time during which a large current is to be supplied to the electromagnet is set to 16 ms, for example, to ensure that the shutter mechanism starts, the amount of time that is wasted in the power supply will be reduced. However, the maximum speed is limited.

(ii) If, as a condition for completely stopping the power supply to the electromagnet, the exposure amount control output signal is given priority over the end signal for a certain period of time to remove the maximum speed constraint, the electromagnet When stopping the power supply from a state where a large current is being supplied, and when stopping the power supply from a state where a small current is being supplied to the electromagnet, the cutting action of the electromagnet is different and the separation movement of the iron piece lever is different. This is inconsistent, causing irregularities in the closing movement of the shutter blades.

Therefore, a second object of the present invention is to perform level conversion from a state of supplying a large current to a state of supplying a small current to the electromagnet by adjusting the output of the light-receiving element circuit when the light-receiving element is once blocked from field light. It is possible to control even when a change signal is generated, eliminating unnecessary power consumption, and constantly outputting exposure control output while the power supply to the electromagnet is converted to a small current. Let the signal occur,
The present invention provides a control circuit for a programmable electric shutter linked to a light receiver, which stabilizes the closing movement of a shutter blade.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

First, in Figure 1, the activation of the shutter mechanism and the closing of the shutter blades are controlled by separate electromagnets, where SPD is a silicon photodiode as a light receiving element, _R1 is a variable resistor for bias adjustment, and OP is a variable resistor for bias adjustment. Operational amplifier, D _L is a diode for logarithmic compression, T _L is a transistor for logarithmic expansion, C ₁ is a capacitor for controlling exposure time, T ₁ is a transistor for controlling the start of light reception time measurement, MG ₁ is a start control for the shutter mechanism. MG ₂ is an electromagnet for shutter blade closure control, R ₂ and C ₂ are electromagnets MG ₁
Resistors and capacitors forming a time circuit to obtain a constant power supply time (e.g. 16ms) to T ₂
is a transistor for controlling the timing start of the circuit, R ₃ and C ₃ are resistors and capacitors for configuring the aborted seconds circuit that regulates the longest exposure time (for example, 48 ms), and T ₃ is for controlling the timing start of the circuit. T ₄ and T ₅ are transistors for driving electromagnets, I ₁ to I ₅ are constant current circuits, CP ₁ to CP ₄ are comparators, FF ₁ and FF ₂ are flip-flops, AG is an AND gate, and NG is a NAND gate. , SW is a switch for generating a start signal for the shutter mechanism.

The silicon photodiode SPD is exposed to field light through a light receiving window for exposure warning when the shutter mechanism (not shown) is at rest, and once the shutter mechanism is activated, it is exposed to field light. The light is blocked, and as the shutter blades are opened, the light is exposed again by the light-receiving pattern.

Although not shown, the exposure warning circuit also controls the potential of the lower end of the capacitor C ₁ to invert the output of the comparator CP ₁ within a predetermined time from the point in time when the cutoff of the transistor T ₁ is controlled by another circuit. It is a real-time format that determines whether the level drops or not.

Next, the operation will be explained.

When a power switch (not shown) is closed by a release operation, power is supplied to each part of the circuit, and an exposure warning circuit (not shown) is activated.

When the release operation further progresses and the switch SW is closed, the flip-flop _FF1 is set and the output Q is inverted to the "H" level and the output is inverted to the "L" level. As a result, transistors T ₂ and T ₃ are respectively cut off, and all inputs of AND gate AG become "H" level, so that the output is inverted to "H" level. Therefore, the transistor _T4 becomes conductive, so that the electromagnet _MG1 is supplied with current and is excited, and the shutter mechanism is activated by the operation of attracting the iron piece lever (not shown).

The activated shutter mechanism temporarily shields the silicon photodiode SPD that was exposed to the field light before the shutter blade is released, and then exposes the silicon diode SPD to the field light again. The shutter blades open as they move.

The output of the opamp OP is on the high level side when the silicon photodiode SPD is exposed to field light, and the output of the silicon photodiode SPD
When it is shielded from the field light, it falls to the low level side.

Therefore, when the output of the operational amplifier OP falls to the low level side, the comparator _CP4 inverts the output to the "H" level, sets the flip-flop _FF2 , sets the output Q to the "H" level, and turns the output back on. Invert to "L" level.

As a result, the AND gate AG is closed, so power supply to the electromagnet MG ₁ is stopped, and the transistor T ₁ is also cut off.

Thus, capacitor C ₁ is charged corresponding to the current flowing through transistor T _L , and capacitor C ₁
When the potential at the lower end of CP1 drops to a predetermined value, the output of comparator _CP1 is inverted to the "L" level, opening NAND gate NG and cutting off transistor _T5 .

Therefore, the power supply to the electromagnet MG ₂ is stopped and the shutter mechanism is activated, causing the unillustrated iron lever, which has been released from inhibition, to move away, and this movement activates the closing drive member to shut the shutter. The blades are closed from the middle of opening or from the fully open position.

In addition, a comparator is connected to the output of the operational amplifier OP.
If the level drop that inverts CP ₄ does not occur, the capacitor C ₂ has already started charging via the resistor R ₂ , so the output of the comparator CP ₂ will go to the "L" level after a certain period of time. When reversed to , power supply to electromagnet MG ₁ is stopped.

In addition, the maximum time (exposure time) for supplying power to electromagnet MG ₂ , including the case where electromagnet MG ₁ cannot activate the shutter mechanism, is limited to the flip-flop.
When _FF1 is set, capacitor _C3 is charged via resistor _R3 , and the time is regulated to the time until the output of comparator _CP3 is inverted to the "L" level after a certain period of time has elapsed.

Next, in Figure 2, the activation of the shutter mechanism and the closing of the shutter blades are controlled by a single electromagnet.The difference from Figure 1 is that the single electromagnet is shown as MG ₃ . dots and transistors
The point is that T ₅ is omitted and a resistor R ₄ is added.

That is, as in the previous embodiment, the flip-flop
When the output Q of FF ₁ is reversed to the "H" level, a large current is supplied to the electromagnet MG ₃ , and the shutter mechanism is activated by the attracted operation of the iron piece lever. Then, when the output of flip-flop FF ₂ is inverted to "L" level, the transistor
Although T ₄ shuts off, the electromagnet MG ₃ continues to hold the shingle lever in the attracted state since a small current drive loop remains through the resistor R ₄ . Furthermore, when the output of the comparator CP ₁ is reversed to the "L" level and the output of the NAND gate NG is reversed to the "H" level, the power supply to the electromagnet MG ₃ is completely stopped, and due to the separation movement of the iron piece lever. The shutter blades are forced to close.

Therefore, at the time when the shutter blade closes when the output of the comparator CP ₁ is inverted to the "L" level, the drive current of the electromagnet MG ₃ is always a small constant current through the resistor R ₄ , regardless of the length of the exposure time. Therefore, the separation movement of the iron piece lever is constant, and no disturbance occurs in the closing operation of the shutter blade.

Further, the maximum time for driving the electromagnet MG ₃ with a large current and the maximum time for driving it with a small current are regulated by the inversion times of the comparators CP ₂ and CP ₃ , respectively.

As described above, according to the present invention, in a type of shutter mechanism in which the start-up is controlled by an electromagnet, wasteful power consumption after start-up can be eliminated, and furthermore, when the exposure control output is generated, Since the driving state of the electromagnet is constant, the demagnetizing operation of the electromagnet is always constant, and the closing movement of the shutter blade is stabilized.

[Brief explanation of drawings]

1 and 2 are circuit diagrams showing different embodiments of the present invention, respectively. SW... Release switch, MG ₁ ... Electromagnet for starting the shutter mechanism, MG ₂ ... Electromagnet for closing the shutter blade, MG ₃ ... Electromagnet for starting the shutter mechanism and closing the shutter blade.

Claims (1)

[Scope of Claims] 1. A light-receiving circuit including a light-receiving element that is placed in a light-receiving state when the shutter is stationary, is temporarily blocked by light when the shutter is activated, and is placed in a light-receiving state again when the shutter is opened, and an exposure light connected to the light-receiving circuit. a time control circuit, a shutter activation control electromagnet that is energized by the shutter release, and a shutter closing control electromagnet that is energized by the shutter release and demagnetized when the appropriate exposure time determined by the exposure time control circuit has elapsed. In a programmable electric shutter linked to a light receiving section, an AND gate circuit is connected to a switch means for an electromagnet for controlling shutter start, and the AND gate circuit is activated by a shutter release to ensure the start of the shutter. A delay circuit having a time constant necessary for the above-mentioned light-receiving circuit is connected to a comparator circuit connected to the light-receiving circuit, and when the light-receiving element is temporarily blocked from light after the shutter release, the light-receiving circuit and the comparator circuit are connected to each other. The switch means is turned off via the AND gate circuit by the earlier signal of the signal emitted by the switch and the signal emitted after the elapse of a predetermined time determined by the delay circuit, and the shutter is started. A control circuit characterized in that a control electromagnet is demagnetized. 2. A light-receiving circuit including a light-receiving element that is placed in a light-receiving state when the shutter is stationary, is once blocked from light when the shutter is activated, and is placed in a light-receiving state again when the shutter is opened; an exposure time control circuit connected to the light-receiving circuit; The shutter is excited by a relatively large current through the switch means turned on by the shutter release, and after the switch means is turned off, the shutter is continuously excited by a relatively small current through the exposure time control circuit. In a programmable electric shutter linked to a light receiver, which is equipped with an electromagnet that closes a shutter that is demagnetized when a proper exposure time determined by an exposure time control circuit has elapsed, an AND gate circuit is connected to the switch means, and the AND gate circuit is connected to the switch means. A delay circuit that is activated by the shutter release and has a time constant necessary to ensure startup of the shutter and a comparator circuit connected to the light receiving circuit are connected to the gate circuit, and the light is received after the shutter release. The switching means is activated by the earlier of the signal emitted via the light receiving circuit and the comparator circuit when the element is once shielded from light, and the signal emitted when a predetermined time determined by the delay circuit has elapsed. is turned off via the AND gate circuit.