Document Type and Number:
Japanese Patent JPS50115030
Kind Code:
A
Abstract:
A digital exposure time control circuit including a standard pulse generating circuit for developing standard rate pulses which are applied under control of a brightness-time conversion circuit to a dividing circuit, and subsequently counted in a reversible counter operating in a counting mode. The number of standard pulses counted are controlled by the brightness-time conversion circuit to be proportional to an exposure time, and the counted pulses are subsequently read-out from the counter to control exposure time. The exposure time control circuit also includes a self-timer control circuit which is responsive to a predetermined number of counted pulses to clear the reversible counter, and enable the brightness-time conversion circuit when the number of counted pulses exceeds the predetermined number in order to develop a delay time, determined by the predetermined number of pulses to which the self-timer is responsive, before the start of counting the pulses for controlling exposure time.
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Application Number:
JP1927274A
Publication Date:
September 09, 1975
Filing Date:
February 18, 1974
Export Citation:
International Classes:
G03B7/093; G03B9/62; G03B9/64; (IPC1-7): G03B7/08; G03B9/08; G03B9/62
Domestic Patent References:
| JPS4817347A | ||||
| JPS4734097U | 1972-12-15 |