Seiko Koki Kabushiki Kaisha

Youichi Seki

Takeo Saito

Kiyoshi Kitai

A camera shutter digital control circuit having a counter for counting a number of pulses representative of exposure time and for reading-out the counted pulses to control exposure time. An adjustable delay circuit synchronizes shutter opening and the initiation of memory read-out. Upon the initiation of shutter opening a signal is applied to the delay circuit, which is adjusted to develop a delay equal to a particular shutter opening time. The delayed signal is then applied to initiate reading-out of the control pulses so that the exposure time is controlled in synchronism with the shutter opening.

Digital camera shutter control circuit having memory read-out/shutter

An electric shutter circuit having an exposure time display disabled in synchronism with the opening of a camera shutter. A brightness-time conversion circuit and a pulse generator together develops a plurality of pulses the number of which is representative of the exposure time and which are stored in a reversible counter. Upon actuation of a shutter release mechanism a display circuit is enabled to display the exposure time by displaying a visual signal determined by the number of pulses stored in the reversible counter. The display circuit is disabled in synchronism with the shutter opening. In one embodiment a Schmidt trigger circuit is triggered by the shutter release mechanism to disable the display circuit.

Shutter control circuit having exposure time display

An exposure time control device of an electric camera shutter includes a brightness time conversion circuit for developing a single pulse having a width representative of the brightness of a subject to be photographed and a reference pulse generating circuit for generating reference pulses at a standard rate. A reversible counter counts the reference pulses for a period of time equal to the duration of the single pulse. Upon termination of the single pulse, a reversible counter control circuit applies control signals to the reversible counter to read-out the count stored therein for controlling the shutter exposure time. A selector switch selects the input position of the reference pulses to the reversible counter in dependence upon exposure time factors other than brightness of the subject thereby enabling the selection of the exposure time in accordance with the subject brightness as well as other factors, such as film sensitivity and diaphragm setting.

Exposure time control device for electric camera shutter

An exposure time control device of an electric shutter includes a brightness-time conversion circuit for developing a single pulse having a width representative of the brightness of a scene to be photographed and a standard pulse generating circuit for generating pulses at a standard rate. A reversible counter counts the standard pulses for a period of time equal to the duration of the single pulse. Upon termination of the single pulse, a reversible counter control circuit applies control signals to the reversible counter to read-out the count stored therein for controlling the shutter exposure time. A delay circuit develops a trigger pulse upon opening of the shutter. The trigger pulse is applied to the reversible counter control circuit, and if it is applied prior to the termination of the single pulse, read-out of the count stored in the reversible counter is initiated prior to termination of the single pulse.

Exposure time control device of electric shutter for camera

An electric camera shutter of the type having a digital recording and reproducing system has a self-timer mode and has a counter circuit for counting and memorizing pulses produced by a pulse generator. In one mode of operation, the exposure time is controlled in accordance with the memorized content of the counter circuit and when in the self-timer mode, the output of the counter circuit controls the energization of a self-timer operation indicator circuit which indicates operation in the self-timer mode.

System for indicating the operation of a self-timer in an electric

A shutter control circuit including a brightness-time conversion circuit for developing an output pulse having a duration representative of exposure time, and a standard pulse generating circuit for generating standard pulses at a certain rate. A reversible counter operable in an addition mode and a subtraction mode counts the standard pulses for the duration of the output pulse of the brightness-time conversion circuit so that the number of counted pulses is representative of exposure time. The reversible counter is then operated in a subtraction mode to read-out the counted pulses to control exposure time. The shutter control circuit further includes circuitry for operating the counter in the addition mode and for applying a selectable number of standard pulses to the reversible counter in order to determine exposure time. When the brightness-time conversion circuit controls the number of standard pulses counted, the control circuit is operative in an automatic mode, and when the number of standard pulses counted are manually selected the control circuit is operative in a manual mode. The shutter control circuit also includes circuitry for reducing the duration of the output pulse of the brightness-time conversion circuit substantially to zero so that the brightness-time conversion circuit is rendered ineffective to determine the exposure time when the shutter control circuit is operated in the manual mode.

Exposure time control device of electric shutter for camera capable of

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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Chiba, Japan

Youichi Seki