Patent · US Expired

Exposure measurement circuit

US4190337A · kind A · utility

1Cited by

9References

7Claims

0Family size

Assignee

VEB Pentacon Dresden Kamera und Kinowerke · DE

Inventors

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

Key dates

Filing date	Jan 30, 1978
Grant date	Feb 26, 1980
Priority date	—
Expiry date	Jan 30, 1998

Classification

Technology area (CPC G)Physics
CPC primaryG03B17/18
WIPO fieldOptics
WIPO sectorInstruments

Abstract

The exposure metering circuit comprises a differential amplifier, whose inputs are connected to a measuring bridge consisting of a photo-conductive cell and setting controls for the insertion of exposure factors and whose outputs are connected to light-emitting elements for the indication of a set under-exposure, over-exposure or the correct exposure. The two measuring bridge feed points are connected across a resistor, on the one hand, and across a transistor which is driven by means of a voltage derived from the common emitter circuit of the differential amplifier, on the other hand, to an operating voltage source.

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