| 摘要 |
Warning circuit of an electric shutter for indicating the conditions of over exposure, wavering of camera resulting from too long exposure time, proper exposure range and overflow of the counter. The electric shutter comprises a photoelectric single pulse generating circuit for generating a pulse indicative of exposure time, a reference clock pulse generating circuit and a logic circuit including a pair of binary counters or an up-down counter assembly having a plurality of stages of the counter units for counting the reference clock pulses during the photoelectric single pulse being generated so as to digitally control the exposure time. The warning circuit comprises a pilot lamp means including a flip-flop circuit and a transistor operated thereby for energizing or disenergizing the lamp. The set input of the flip-flop circuit is supplied from the output of a selected stage of the counter units for counting the pulses corresponding to the time of over exposure, proper exposure range, wavering of camera and overflow of the counter so that the flip-flop circuit is actuated by the selected stage to indicate the required condition.
|
