JPS5681481A - Electronic clock - Google Patents

Abstract

PURPOSE:To enhance the accuracy of the electronic clock by presetting a frequency- dividing circuit periodically in accordance with the output of the temperature detection controlling the pulse-width of an indication driving pulse. CONSTITUTION:By a sampling signal of a prescribed time width of the shift output of a shift register 10 corresponding to the counted value of a watch counting circuit 5, a switch N1 is made conductive sequentially and an information corresponding to the temperature detected by a temperature detecting circuit formed of a thermistor 26 and a comparator 14, etc. is latched by latch circuits 15-18. By these latch outputs, the output of AND circuits 191-194 is controlled, the driving pulse width is changed according to the temperature through the intermediary of a pulse width controlling circuit 20, the driving excution voltage of a matrix liquid-crystal indicating body 9 is controlled, and thus an indication with an excellent contrast characteristic is performed. Meanwhile, by the output changing with a prescribed detection temperature by the circuit 191 as a boundary, the term of set and reset of FF3 is changed, the frequency-dividing circuit 4 is preset periodically, the number of the frequency-dividing pulse for the watch is compensated according to whether it is above or below the prescribed temperature, and thus time counting of high accuracy is performed.