Electronic shutter control circuit having exposure time indicato

Details Electronic shutter control circuit having exposure time indicato Electronic shutter control circuit having exposure time indicato

1974-12-23

1976-10-19

Peters Jr., Joseph F.

354 60L, 354127, G03B 708, G03B 1718

Patent

active

039874648

ABSTRACT:
An electronic camera shutter control circuit having an indicator for indicating when the camera shutter is open. A circuit responsive to a control signal controls a current flow through an electromagnet which is energized during the opening of the camera shutter to prevent the shutter release mechanism from closing the shutters. An indicating element indicates that current is flowing through the electromagnet and therefore indicates that the shutter is open. A control circuit having a photoresponsive element develops a control signal determined by the brightness of the scene to be photograhed and applies the control signal to the circuit responsive to the control signal. The control circuit includes a capacitor which is charged at a rate determined by the conductivity of the photoresponsive element which varies according to the light sensed. When the voltage stored in the capacitor exceeds a predetermined value, the circiut responsive to the control signal deenergizes the electromagnet so that the camera shutter closes. The circuit responsive to the control signal comprises a pair of transistors with their respective emitters connected to the indicator.

REFERENCES:
patent: 3504604 (1970-04-01), Kitai
patent: 3672267 (1972-06-01), Harvey et al.
patent: 3678821 (1972-07-01), Kitai
patent: 3698299 (1972-10-01), Arisaka et al.
patent: 3712194 (1973-01-01), Yoshimura
patent: 3765311 (1973-10-01), Nobusawa
patent: 3800683 (1974-04-01), Nobusawa
patent: 3821756 (1974-06-01), Kitai
patent: 3846814 (1974-11-01), Yata et al.
patent: 3868705 (1975-02-01), Katai

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