Communications: electrical – Audible indication – Percussion-type sound producer
Patent
1976-01-26
1979-01-02
Miller, Charles D.
Communications: electrical
Audible indication
Percussion-type sound producer
354 23D, 356218, H03K 1303
Patent
active
041329856
ABSTRACT:
This invention relates to an automatic camera exposure control device comprising a first light measuring circuit including a photoelectric element receiving light through the objective lens of the camera and generating a first output proportional to the logarithm of the brightness of an object to be photographed, and a circuit for providing a second output indicative of the film sensitivity and the lens aperture value, the light measuring circuit for providing a first signal indicative of the sum of the first and second outputs and a second circuit including a pulse genrator circuit for generating clock pulses and a counter for counting the clock pulses and for producing a second signal of a stairstep waveform corresponding to the counting of a pulse; a voltage comparator circuit for comparing the second signal with the first signal and for producing a signal when the level of the second signal exceeds that of the first signal; a third circuit composed mainly of a gate circuit for stopping the counting of the pulse upon receipt of the threshold level signal from the voltage comparator circuit; and a shutter control circuit including a transistor for inverse logarithmic conversion and for producing a collector current proportional to the exponent of the second signal applied to its base, and a capacitor to be charged by the collector current of the transistor and a switching circuit responsive to the voltage charged in the capacitor in excess of a predetermined level for actuating the shutter to terminate the exposure interval.
REFERENCES:
patent: 3124794 (1964-03-01), Patmore
patent: 3553443 (1971-01-01), Neil
patent: 3807879 (1974-04-01), Mori
Miller Charles D.
Minolta Camera Kabushiki Kaisha
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