Light quantity measuring system

Details Light quantity measuring system Light quantity measuring system

1988-04-20

1989-06-27

Adams, Russell E.

354458, G03B 7091

Patent

active

048434191

ABSTRACT:
A light quantity measuring system with a function of controlling an exposure comprises a capacitor an anode potential of which drops from a predetermined level to a set-up reference level with a rate of change responding to a quantity of light incident on a photodiode through which a discharging current of the capacitor flows. A counter counts a pulse signal with a set-up repetitive frequency, the counted number of which represents a quantity of the light. A counting condition setting means sets the reference level and the repetitive frequency in response to a counted number in the counter so as to prevent an overflow of the counter. A calculating means calculates a quantity of light based on the counted number, the reference level and the repetitive frequency.

REFERENCES:
patent: Re29776 (1978-09-01), Kohtani
patent: 3677151 (1972-07-01), Werner et al.
patent: 3703130 (1972-11-01), Watanabe
patent: 3836262 (1974-09-01), Yata et al.
patent: 3876876 (1975-04-01), Kitai et al.
patent: 4191459 (1980-03-01), Saito et al.
patent: 4249109 (1981-02-01), Ogawa

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