Memory used in automatic exposure control mechanism

Details Memory used in automatic exposure control mechanism Memory used in automatic exposure control mechanism

1980-08-29

1982-03-02

Adams, Russell E.

354 50, 354 51, 354 43, G03B 700

Patent

active

043176232

ABSTRACT:
In a through-the-lens, single lens reflex camera wherein light reflected from an object to be photographed is intercepted when a quick-release mirror jumps up in response to the depression of a shutter button to one of a plurality of positions, a system for generating and supplying a voltage signal corresponding to the intensity of the reflected light for use in a circuit for opening and closing the camera shutter or a circuit for opening or closing the camera diaphragm. An input pulse generator generates an input pulse signal having a first frequency related to the intensity of the light reflected from the object to be photographed and a reference pulse generator generates a reference pulse signal having a second frequency. A phase lock loop generates a control pulse signal having a third frequency and compares the frequency of the input pulse signal to the frequency of the control pulse signal when the reflected light is not intercepted by the quick-release mirror to produce and supply the voltage signal to the shutter or diaphragm circuit, and adjusts the frequency of the control pulse signal and the reference pulse signal to coincide with the frequency of the input pulse signal. When the quick-release mirror intercepts the reflected light, the reference pulse signal is supplied to the phase lock loop to maintain the generation of the output pulse signal. The reference pulse signal generator can be embodied by a second phase lock loop.

REFERENCES:
patent: 3712191 (1973-01-01), Nobusawa
patent: 3858224 (1974-12-01), Heaney
patent: 3858226 (1974-12-01), Nakagawa et al.
patent: 4048643 (1977-09-01), Arita

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