The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 19, 1977
Filed:
Apr. 18, 1975
Armin Stiller, Braunschweig, DT;
Rollei-Werke Franke & Heidecke, Braunschweig, DT;
Abstract
Electronic flash apparatus of the general type having exposure-measuring and flash-limiting mechanism comprising a light-sensitive element connected in series with an integrating capacitor and a thyristor, arranged so that when the thyristor becomes conductive, it causes a pulse which interrupts or terminates the flash. In distinction from prior flash apparatus of this same general type, the present apparatus has circuitry in which one plate of the integrating capacitor is connected to the collector of a photo-transistor and the other plate is connected to the control grid of the thyristor and to a higher voltage source, while the emitter of the photo-transistor is connected to a lower voltage source. Other circuit details are disclosed, resulting in a flash unit which is less trouble-prone and easier to adjust than prior flash units of the same general type, and which compensates for the close-up effect so that pictures taken at close range are not over-exposed, as happens so often with many of the prior art flash units.