Rollei-werke Franke & Heidecke

Arthur Schneider

A light detecting and measuring device for use with an electronic flash unit comprises a phototransistor, integrating capacitor and diodes connected in circuit to the flash unit. The diodes and capacitor are connected to the phototransistor and responsive to signals from the flash unit for enabling measurement of light by the phototransistor only while the flash unit is operating thus preventing measurement from external light sources.

Light measuring unit for an electronic flash device

A control circuit for rapid charging of an accumulator with a pulsating current includes a transistor arranged for switching the charge current on and off. The collector circuit of the transistor has an emitter resistor arranged to establish a control voltage that is substantially constant throughout each pulse of the charge current, and a comparator has an output connected to the base of the transistor and inputs from a reference voltage and the voltage on the accumulator so as to block the transistor when the charge voltage exceeds the reference voltage. The emitter resistor is preferably an incandescent lamp, a zener diode is preferably arranged in parallel with the lamp to provide a constant voltage for the base-emitter circuit of the transistor, and a complementary transistor is preferably connected with the switching transistor to form a two-stage transistor circuit.

Rapid-charging circuit

In a light-generating electronic flashlight which has a reflector and first and second discs which may be selectively placed ahead of the reflector for normal and wide-angled illumination of an object to be photographed, respectively, the improvement includes third and fourth discs which may be placed ahead of the reflector. Each of the third and fourth discs have parallel prismatic elements for unilateral deflection of the light generated by the flashlight for the third and fourth discs to displace the flashlight-generated light upwardly and laterally, when the third and fourth discs are placed ahead of the reflector, respectively, and upon the flashlight being in an upright position and directed towards the object to be photographed.

Electronic flashlight for direct and indirect flashing

An electronic flash unit for photographic purposes, with improved means for quenching the flash when sufficient light has been emitted from the flash tube. The discharge circuit of the main storage capacitor comprises the flash tube and a switch thyristor in series with each other. A quench circuit including a quenching capacitor and a quenching thyristor will deliver a quenching current to the switch thyristor when the quenching thyristor is triggered by exposure metering and flash limiting mechanism, this mechanism including a resistor, a phototransistor, and an integrating capacitor in series with each other and in parallel with a feed capacitor which supplies feed current to the exposure metering and flash limiting mechanism, and which is in parallel with the switch thyristor.

Electronic photographic flash apparatus

Photographic flash apparatus having one flash unit which may be called the main or master or primary flash unit, and one or more additional flash units which may be called secondary or slave or dependent units. Eliminating connecting cables often used in the prior art, and also eliminating ratio frequency controls sometimes used in the prior art relating to multiple units, the secondary or dependent units of the present invention are independently powered and are triggered to initiate a flash by the light from the flash of the main unit, and triggered to terminate or discontinue the flash in each dependent unit when the flash in the main unit turns off. The control of each secondary unit is entirely by means of the flash of light from the main unit. The apparatus is particularly useful in studio lighting where it is desired to illuminate the subject being photographed from a plurality of different directions.

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Volkenrode, Germany

Arthur Schneider