Patent · US Expired

Camera circuit arrangement for the pre-indication of exposure time

US3997904A · kind A · utility

2Cited by

3References

3Claims

0Family size

Assignee

VEB Pentacon Dresden · DE

Inventors

Siegfried Schutze · Dresden, DE
Werner Locke · Radebeul, DE

Key dates

Filing date	May 16, 1975
Grant date	Dec 14, 1976
Priority date	—
Expiry date	May 16, 1995

Classification

Technology area (CPC G)Physics
CPC primaryG03B7/08
WIPO fieldOptics
WIPO sectorInstruments

Abstract

A circuit arrangement for the pre-indication of the exposure time to be expected in automatic mirror-reflex cameras in which the brightness of a controllable luminous element, which is constant for the duration of the exposure, is used for the illumination of the photo-receiver of the electronic time-formation system. The voltage dropping over the luminous element, which is proportional to the exposure time, is ascertained by means of a measuring mechanism. The luminous element is formed as luminous diode and in parallel therewith there is connected a current path containing the measuring mechanism fed from a constant current source for the compensation of the response voltage of the luminous diode and for the adaptation of the measuring mechanism to the characteristics of the luminous diode.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.