Exposure information storage device for a photographic camera

An exposure information storage device for a camera capable of storing the exposure information supplied thereto comprising:

• (a) an exposure information producing means for providing an analog value corresponding to a supplied exposure information;
• (b) a pulse generating means for producing pulses at a predetermined period;
• (c) a counter means for counting pulses from the pulse producing means;
• (d) a digital-to-analog conversion means responsive to said counter means for providing an analog electrical value representative of the content of the counter;
• (e) a comparator means for comparing the analog value from the exposure information producing means with the analog electrical value from the digital-to-analog conversion means, the output of said comparator means being changed from a first signal to a second signal when both analog values reach a predetermined relation with each other;
• (f) a transmitting means for transmitting the pulses from the pulse producing means to the counter means in response to the first signal and for prohibiting the transmission of the pulses from the pulse producing means to the counter means in response to the second signal;
• and
• (g) a control circuit coupled to the transmitting means, said circuit for applying an independent signal from the output of the comparator means to the transmitting means corresponding to the first signal for a certain determined time in synchronization with said pulses.

An exposure information storage device for a camera capable of storing the exposure information supplied thereto comprising:

• (a) an exposure information producing means for providing an analog value corresponding to a supplied exposure information;
• (b) a pulse generating means for producing pulses at a predetermined period;
• (c) a counter means for counting pulses from the pulse producing means;
• (d) a digital-to-analog conversion means responsive to said counter means for providing an analog electrical value representative of the content of the counter;
• (e) a comparator means for comparing the analog value from the exposure information producing means with the analog electrical value from the digital-to-analog conversion means, the output of said comparator means being changed from a first signal to a second signal when both analog values reach a predetermined relation with each other;
• (f) a transmitting means for transmitting the pulses from the pulse producing means to the counter means in response to the first signal and for prohibiting the transmission of the pulses from the pulse producing means to the counter means in response to the second signal;
• and
• (g) a control circuit coupled to the transmitting means for applying a signal corresponding to the first signal to the transmitting means for a predetermined time in synchronism with said pulses independently of the output of the comparator means.

An analog-to-digital converter circuit for storing an analog input signal supplied thereto comprising:

• means for providing an analog input signal for storage;
• means for providing pulses;
• a counter responsive to said pulse providing means for counting pulses;
• digital-to-analog conversion means for converting the content of the counter into an analog output signal;
• a control circuit for terminating the pulse counting operation of the counter and having a comparator responsive to the analog input signal and the digital-to-analog output signal for providing a completion signal to terminate the pulse counting operation of said counter when said two analog signals are related in a predetermined manner
• and a control means to prevent the count stopping operation by the control circuit during changing of the output of the digital-to-analog conversion means at the time of pulse counting by the counter.

An analog-to-digital conversion device for a camera comprising:

• (a) an exposure information producing circuit for providing an analog output corresponding to a supplied exposure information;
• (b) a pulse producing circuit for forming pulses;
• (c) an analog-to-digital conversion circuit including a counter means for counting the pulses, a digital-to-analog conversion means for converting a content of the counter means into an analog value, detecting means for detecting the analog value and the analog output and producing a signal for stopping the count operation of the counter means when the analog value and the analog output reach a predetermined relation;
• (d) preventive means for avoiding the stopping of the count operation with the signal from the detecting means due to temporary changes in the output of the digital-to-analog conversion means during counting by the counter means.