Electric shutter control circuit

Claim 2

An electric shutter control circuit comprising a first pulse oscillator means for producing a train of pulses at a pulse frequency corresponding to the illumination intensity of the scene to be photographed, control means for establishing a time interval in accordance with exposure parameters other than scene brightness, a multi-stage counting and memorizing means operable prior to an exposure for counting and memorizing the number of pulses produced from said first pulse oscillator means during said interval, a second pluse oscillator means for producing a train of pulses at a predetermined pulse frequency and operable after said interval for shifting the content of the counting and memorizing means to the last stage thereof, and a shutter circuit receiving the last stage output of said counting and memorizing means including means responsive to the time required for shifting the content of said counting and memorizing means to the last stage thereof for controlling the open time of a shutter.

Claim 3

An electronic shutter control circuit according to claim 1, which further comprises indicating means provided at individual output stages of said counting and memorizing means, said indicating means indicating the shutter speed.

Claim 4

An electric shutter control circuit according to claim 1, which includes a first switch interlocked to the operation of depressing a shutter release button said control means comprising, a pulse generator producing in response to the action of said first switch a pulse having a time length corresponding to photographing conditions such as stop value and film sensitivity, said pulse generator producing a pulse having a predetermined time length for existing said conditions in response to the action of opening the shutter, and a said first pulse oscillator oscillated means in a preliminary shutter-off stage prior to the photographing in response to the output of said pulse generator at a pulse frEquency corresponding to the illumination intensity of the scene to be photographed, said second pulse oscillator means being oscillated in response to the action of opening the shutter during the presence of the output produced from said pulse generator at a predetermined frequency sufficient to shift the content of said counting and memorizing means to the last stage thereof, and in which said counting and memorizing means comprises a binary counter to count the output pulses of said pulse oscillator, a discriminating means for producing only output signals from said binary counter representing powers of 2 and a shift register memorizing the output of said discriminating means.

Claim 5

An electric shutter control circuit according to claim 1, which includes a first switch interlocked to the operation of depressing a shutter release button said control means comprising, a pulse generator producing in response to the action of said first switch a pulse having a time length corresponding to photographing conditions such as stop value and film sensitivity, and said first pulse oscillator means oscillated in a preliminary shutteroff stage prior to the photographing in response to the output of said pulse generator at a pulse frequency corresponding to the illumination intensity of the scene to be photographed, said second pulse oscillator means being oscillated at the time of opening of the shutter in response to the output of a second switch actuated upon the action of opening the shutter to produce pulses at a predetermined frequency sufficient to shift the content of said counting and memorizing means to the last stage thereof, and in which said counting and memorizing means comprises a binary counter to count the output pulses of said pulse oscillator, a discriminating means for producing only output signals from said binary counter representing powers of 2 and a shift register memorizing the output of said discriminating means.