GB1536709A - Electronic timepieces - Google Patents

Abstract

1536709 Electronic timepieces DAINI SEIKOSHA KK 23 Dec 1976 [29 Dec 1975] 53944/76 Heading G3T A digital electronic timepiece has hours, minutes and day of the week display portions and a display portion for selectively indicating either the date or seconds. Setting arrangements are provided, seconds being automatically displayed when a time of day correction is effected; 12 hr or 24hr mode is selectable and AM/PM indication accordingly. Any or all display portions may be caused to flash when battery voltage is too low. The timepiece Fig. 1 comprises a crystal controlled oscillator, frequency divider 45, level shifter 46, frequency divider 49, seconds counter 50. Counting circuits 53, 61, 62, 70, 78 are used in 12 hr mode operation and 54, 63, 71, 79 in 24 hr mode operation. The operative mode is determined by state of a flip-flop 20 controlled by switches 3 and 4. Each counter in a set is connected to a succeeding counter via a respective electronic switch. Electronic switches selectively couple the counters to respective decoder/drivers 56, 65, 73, 82 to operate mins, hours, day display devices 57, 66, 74 respectively. Display device 83 will receive the secs or date count value via switch circuit 81 and decoder 82, depending upon the position of a manual switch 1 acting on a flip-flop 35. Setting A switch 2 functions as a safety and reset switch. A switch 3 selects digits to be corrected, a shift register 18 receiving a shift pulse each time switch 3 is closed. In normal operation of the timepiece the register output N is at "H" level. If switch 3 is then closed, the "H" level shifts to output DM the other outputs being at "L" level. Therefore only the date will be displayed. To advance the date, switch 4 is operated, a pulse being applied via electronic switch 76 to the date counter 79 each time switch 4 is closed. The mins and hours counters are similarly selected by switch 3 and corrected by switch 4, the respective display being advanced by one unit each time switch 4 is closed. Battery condition indicator A battery voltage detector circuit 36 operates once per day, as it is controlled by AM/PM counter 62. If the voltage is low circuit 36 sets a flip-flop 37 so that NAND 42 passes inverted signals from seconds counter 50 to control terminals of decoder/drivers 56, 65, 73, 82 causing the display to flash. Testing A terminal 48 is provided whereat a high frequency can be injected to the timekeeping circuit for testing. A terminal 85 is provided at which an "H" level signal may be applied whereby all the counters are set to a predetermined time. Thus the displayed contents become 59 sec 59 min 23.00 hrs Sat 31st. After the elapse of 1 sec they will become 00 sec, 00 min, 00 hrs, Sun 1st confirming that the counters are operating satisfactorily.