Optics: motion pictures – Removable film strip magazine type
Patent
1976-06-29
1978-02-07
Hix, L. T.
Optics: motion pictures
Removable film strip magazine type
354 43, 354 44, 354 51, 352141, 356223, 307357, 318640, G03B 708, G05B 106, G01J 142, H03K 520
Patent
active
040729621
ABSTRACT:
A metering device comprises a photoelectric converter circuit for generating a first voltage corresponding to the brightness of a subject to be photographed. The converter circuit includes a photoelectric converter element and a first conductor element for logarithmically converting the output of the photoelectric converter element. The device further comprises a voltage generating circuit including a second semiconductor element and a current source for flowing a current proportional to an absolute temperature to a resistor connected in series to the second semiconductor element. The voltage generating circuit is effective to generate a second voltage comprising the sum of the voltages generated in the resistor and the second conductor element. The difference beween the first and the second voltage is put out by a differential amplifier. A third voltage proportional to the absolute temperature is put out by a voltage generating circuit, and the third voltage and the output voltage of the differential amplifier are compared by a comparator circuit. Means is provided for equalizing the output voltage of the differential amplifier and the third voltage by the output of the comparator circuit.
REFERENCES:
patent: 3747487 (1973-07-01), Tanikoshi
patent: 3776111 (1973-12-01), Maida
patent: 3798662 (1974-03-01), Suzuki
patent: 3829867 (1974-08-01), Ono
patent: 3935524 (1976-01-01), Cap et al.
patent: 3936842 (1976-02-01), Narba et al.
patent: 3977011 (1976-08-01), Matsuda
Hix L. T,.
Nippon Kogaku K.K.
Perkey William B.
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