Device for indicating exposure information in the viewfinder of

Details Device for indicating exposure information in the viewfinder of Device for indicating exposure information in the viewfinder of

1974-07-29

1976-05-11

Corbin, John K.

Optics: measuring and testing

Photometers

Photoelectric

356226, 356227, 354230, 354 60L, G01J 142, G03B 708

Patent

active

039558924

ABSTRACT:
Light emitting elements such as light emitting diodes provided in the viewfinder of a camera are connected with a light measuring circuit including a photodetector through an A-D converter, a decoder and a gate circuit so that the light emitting elements may indicate exposure information in a digital form in accordance with the output of the light measuring circuit. An oscillator is connected with the A-D converter and the gate circuit for giving sampling pulses to the A-D converter and clock pulses to the gate circuit. Between the oscillator and the gate circuit is provided a duty modulator to change the duty cycle of the square wave transmitted from the oscillator to the gate circuit. The duty modulator is connected with the light measuring circuit or the A-D converter so as to control the duty cycle of the square wave in accordance with the output from the light measuring circuit. the brightness of the light emitting elements in the viewfinder is controlled so as to be proportional to the brightness of the image viewed through the viewfinder.

REFERENCES:
patent: 3261273 (1966-07-01), Broschke
patent: 3416032 (1968-12-01), Jahns et al.
patent: 3473084 (1969-10-01), Dodge
patent: 3843265 (1975-10-01), Egli et al.

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