| 摘要 |
PURPOSE:To reduce the power consumption of an electronic clock by providing one photodetection quantity detecting circuit for plural photodetecting elements and using it on a time-division basis, and making the period of sampling pulses different according a correction state, a noncorrection state, and a storage state. CONSTITUTION:The voltage of the photodetecting elements 5-7 with a control function arranged under a display device 2 equipped with time display parts 2a-2c, a timer signal ft and clock signals f1 and f2 with a one-second period generated by a frequency dividing circuit 11, and a carry signal fm outputted by the second counter 13 of a timer circuit 12 are inputted to a sampling pulse generating circuit 50, sampling pulses Ps which differ in period according to the condition of a terminal C1 are inputted to a generating circuit 60, and output photodetection signals P5-P7 are outputted to a dark state detecting means OR gate 100 and a photodetection condition decision circuit 20. The gate 100 outputs a signal Ph to the circuit 50 when the signals P5-P7 are all in a dark state and a correction permitting signal Pc and a correction digit selecting signal Psl outputted by the circuit 20 and the timer signal ft passed through the circuit 12 are inputted to a display driving circuit 17 and outputted to the device 2, so that the time is displayed. |
