Electronic slave flash delay device
AssigneeVivitar Corporation
InventorJean M. Orban
Life of this patent
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Abstract
A device for activating an electronic slave flash unit for photographic use includes a circuit wherein there is a delay circuit responsive to a light sensing signal after a predetermined time delay to activate a flash unit. The time delay of the delay circuit is adjustable as required, and the delayed operation of the flash of the slave flash unit eliminates incorrect impulse signals being transmitted to light sensors of other slave flash units which would otherwise prematurely extinguish their flash and give a resultant incorrect lighting effect. The power for the circuit is obtained from a capacitor which is energized by a flash unit. The energy in the capacitor is used to power the delay circuit, and a Zener diode and unijunction transistor and variable resistance permit accurate variable time delays.
Claims33
A device for activating an electronic slave flash unit including in a circuit
- light sensing means adapted to be responsive to a light impulse from a master flash unit to thereby generate a first signal;
- delay circuit means including control means for providing different time delays, said delay circuit means being responsive to said first signal and operative, after a predetermined selected time delay, to generate a switching signal;
- and
- switching means responsive to the switching signal and adapted to activate the associated flash unit.
A device for activating an automatic electronic flash unit including in a circuit
- light sensing means adapted to be responsive to a light impulse from a master flash unit and thereby generate a signal, such light sensing means including an amplifier;
- switch means responsive to the signal from the amplifier to transmit a trigger signal;
- delay circuit means including control means for providing different time delays, said delay circuit means being responsive to the trigger signal and operative, after a predetermined selected time delay provided by the delay circuit, to generate a switching signal, said time delay being adapted to be at least substantially the duration of the light impulse;
- and
- switching means responsive to the switching signal and adapted to activate the associated flash unit.
A device for activating an automatic electronic slave flash unit including in a circuit
- light sensing means adapted to be responsive to a light impulse from a master flash and thereby generate a signal;
- delay circuit means including means selectively switchable into circuit for providing different predetermined time delays, and means being responsive to the trigger signal and operative, after a selected predetermined time delay in the range between substantially one millisecond and eight milliseconds as provided by the delay circuit, to generate a switching signal;
- and
- switching means responsive to the switching signal and adapted to activate the associated flash unit.
A device for activating an electronic slave flash unit having a circuit including a photodiode responsive to a light impulse to generate a signal, an amplifier for said signal, switch means and the amplifier output feeding said switch means, an energy storing capacitor powering the circuit, a delay circuit including a unijunction transistor and a bank of resistors, a chosen resistor being connected to determine the time delay of the delay circuit operation, operation of the switch means generating a trigger signal wherein energy stored in the capacitor powers the delay circuit, a thyristor, the delay circuit operation passing a switching signal to the gate of the thyristor connected across terminals for a flash unit, the signal activating the thyristor to close the circuit across the terminals and so activate a flash, a zener diode in the delay circuit regulating the voltage supply to the delay circuit thereby to ensure an accurate time delay for the delay circuit.
A system of operating electronic flash units with a camera, wherein slave flash units are flashed in sequence after generation of a master flash initiated by the camera, the flashes of the various slave flash units being triggered by light impulse sensors with the flash units and the flashes of each flash unit being delayed relative to each other until substantial completion of the flash from the previous flash unit by a delay circuit operative with each slave flash unit, the master flash and the time delayed flashes of the slave units occurring within the shutter open time of the camera.
A method of operating an electronic slave flash device including the steps of
- selecting a time delay for the device between the activation of the device and the initiation of a flash by the device;
- sensing a light impulse to activate the device;
- generating a first signal in response to sensing the light impulse;
- initiating a delay circuit with such first signal;
- generating a switching signal from the delay circuit after the selected time delay;
- and
- activating switching means with such switching signal to fire the flash of a flash device.
For use with electronic flash units in flash photography, wherein one or more slave flash units are flashed after generation of a flash from a master flash unit initiated by a camera, at least one or more of the slave flash units or the master flash unit being automatic, a device for activating a slave flash unit including in a circuit, light sensing means adapted to be responsive to a light impulse from a master flash unit to thereby generate a first signal, delay circuit means including control means for providing different time delays, said delay circuit means being responsive to said first signal and operative, after a predetermined selected time delay to generate a switching signal, and switching means responsive to the switching signal and adapted to activate the associated slave flash unit.
An electronic slave flash unit including in a circuit
- a flash unit,
- light sensing means adapted to be responsive to a light impulse from a master flash device to thereby generate a first signal;
- delay circuit means including control means for providing different time delays, said delay circuit means being responsive to said first signal and operative, after a predetermined selected time delay, to generate a switching signal;
- and
- switching means responsive to the switching signal and adapted to activate the associated flash unit.
A device for activating an electronic slave flash unit including in a circuit
- light sensing means adapted to be responsive to a light impulse from a master flash unit to thereby generate a first signal;
- delay circuit means for providing a delay duration of at least substantially the duration of the light impulse from the master flash, said delay circuit means being responsive to said first signal and operative, after a predetermined time delay, to generate a switching signal;
- and
- switching means responsive to the switching signal and adapted to activate the associated flash unit.
Dependencies are inferred from the claim text.