GB1535342A - Electronic timepieces - Google Patents

Abstract

1535342 Electronic timepieces DAINI SEIKOSHA KK 13 Oct 1976 [15 Oct 1975] 42537/76 Heading G3T An electronic timepiece with digital display, e.g. liquid crystals, is arranged to display time of day in hours, minutes and seconds and, on the same display devices, chronograph time in either hours minutes and seconds or tenths and hundredths of seconds in dependence upon the state of a manual selector switch means. For chronograph operation, a switch SW1 Fig. 1 is closed, and transmission gates 13-18 are controlled to select the contents of counters 3 and 4 or 5 and 6 for display. With a switch SW2 open, the count in seconds counters 5, 6 is applied via transmission gates 14, 16, 18 to a decoder-driver 19 which causes the seconds and tens of seconds indication. In addition, a driver circuit 26 causes the display of the count in minutes and hours counters 7-10. In the driver circuit 26, AND gates 24 receive a 32Hz pulse train derived from oscilator circuit_1, and AND gates 23 receive the pulse train (i.e. 32 Hz) via an inverter and transmission gate 21. The common electrode of the display receives the 32 Hz pulse signal. If an output of decoder 22 is logic "I", a respective AND gate 23 is open to pass the 32 Hz pulses via an OR gate 25 to an appropriate display segment so that a potential difference exists between that segment and the common electrode. If switch SW2 is closed, with switch SW1 still closed, the transmission gates 14, 16, 18 will be blocked and transmission gates 13, 15, 17 opened to pass the output of the 1/100 seconds and 1/10 seconds counters 3, 4 to the decoder-driver 19 for display on the same devices previously used for seconds display. In addition, gate 21 is blocked and gate 20 is opened to pass the 32 Hz pulses to AND gates 23 instead of the 32 Hz pulses, the AND gates 24 receiving the 32 Hz pulses as before. Therefore the OR gates 25 will pass the 32 Hz pulses to the display segments whether the decoder 22 outputs are high or low. Consequently there will be no potential difference between the common electrode and segments and hence no display of hours and minutes.