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US 4,052,644 AGranted
Electronic flash unit with operational signal
AssigneeRollei-Werke Franke & Heidecke
InventorStefan Borejko
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AssigneeRollei-Werke Franke & Heidecke
InventorStefan Borejko
Estimating the term…
An electronic flash unit having the conventional flash tube, storage capacitor dischargeable through the flash tube, measuring device for recording the quantity of light emitted by the flash tube and reflected back from the subject being photographed, a pulse generator responsive to the measured reflected light, and means for quenching the flash in response to a pulse produced when the measured reflected light reaches a threshold value. The present flash unit, in addition to the conventional features just mentioned, includes the novel feature of a light-emitting diode which becomes illuminated when the light measuring means and the pulse generator circuit become operative, thus signalling to the user of the device that the so-called "computer" mechanism has actually operated. Circuit means is provided for extinguishing the light-emitting diode at the proper time. By incorporating such a light-emitting diode in the flash unit, the operator is informed of the operativeness of the computer in a more satisfactory way than is possible with prior art devices which notify the operator, the present invention being particularly useful in informing the operator of the functioning of the computer mechanism during each flash in a rapid succession of flashes, not possible in the customary prior art constructions.
An electronic flash unit, comprising a flash tube, a storage capacitor dischargeable through said flash tube, flash measuring means responsive to the quantity of light emitted by the flash tube and reflected back from a photographic subject being photographed, a pulse generator circuit device, means for rendering said pulse generator circuit device operative to produce a pulse when an adjustable value of light has been measured by said measuring means, a flash tube quenching device, and means for rendering said quenching device operative in response to said pulse, characterized by a direct current source (25), an electronic switch, a light-emitting diode (29) connected to said direct current source (25) through said electronic switch, means for closing said electronic switch in response to a signal derived from one of said devices, and means for opening said electronic switch automatically after an adjustable closing period.
The invention defined in claim 9, wherein said adjusting means includes a capacitor (35) and an adjustable resistor (33).
An electronic flash unit comprising means for producing a light flash, computer means responsive to light reflected from a subject being photographed for terminating a light flash when the such reflected light reaches a threshold value, a light-emitting diode, and circuit means responsive to operation of said computer means for supplying current to said light-emitting diode to produce light therefrom when said computer means is operated, so that such light from said diode may serve as an indication that said computer means has operated, further comprising means for adjusting the length of time that light is produced from said diode in response to an operating cycle of said computer means.
Dependencies are inferred from the claim text.