Patent GB-1419595-A (GB)
Title: Solid state watch with calendar display
IPC: G04G9/08
Filed: 1973-03-06
Abstract: 1419595 Electronic watches TIME COMPUTER Inc 6 March 1973 10892/73 Heading G3T An electronic watch with an electro-optical numeric display is arranged to selectively indicate on demand either the time of day (i.e. hours and minutes) or the date (day and month) on the same display elements. Each element or display station may comprise a 7-bar segment array of light emitting diodes, as shown Fig. 3, or a 27-dot matrix thereof, or may comprise liquid crystal, ferroelectric crystal or electro-luminescent materials. A.M./P.M. is also indicated. The watch comprises integrated circuit modules 70, 141, Fig. 3 forming a time computer and calendar computer respectively. TIME INDICATING The operation of the time computer circuit 70 is substantially as described in Specification 1342164, and the circuit is illustrated in Figs. 4a, 4b, 4c (not shown). Briefly it comprises hours (180), minutes (176, 178) and seconds (172, 174) counting registers formed by binary chains of MOS elements - fed by a 1Hz signal from a frequency divider chain (30) (164). The divider is fed from a quartz crystal controlled oscillator. The outputs of the registers are fed, via respective selection or transmission gates to a common decoder (186). This converts binary coded decimal signals from the registers into suitable drive signals which are applied via buffer amplifiers to the displays. As shown Fig. 3, the said amplifiers outputs a to f go to control energization of the anodes of respective segments a to f in each display station 74, 76, 78, 80 via transistors 112, 114, 116, 118, 120, 122, 124. All of the cathodes of the diodes in each display station are connected to the supply (3 volt battery 72) in common through a strobing transistor for that time unit display station, transistors 86, 88 serving the minutes display in the stations 78, 80 while transistors 90, 92 serve the seconds display in those same stations. When a "read" switch 132 is operated, hours and minutes are displayed for a controlled time period (1“ seconds). If the switch 132 is maintained closed then seconds will be displayed. DATE INDICATING Upon demand by a date switch 138, the calendar circuit 141 acts to display, on display stations 74, 76, 78, 80, the day and month numerically, and A.M. or P.M. on colon dots 81, 83 respectively. Upon closure of date switch 138 the transmission gates for feeding time information to the decoder (186) are disabled and date information in BCD form is fed via terminals 1 to 4 and Q1 to Q4 and transmission gates (284), Fig. 4a (not shown) to the decoder (186) in circuit 70. The calender circuit 141 is detailed in Figs. 6a, 6b and comprises an A.M./P.M. counter 342, a day counter 344, a month counter 346, a strobe circuit 348 and transmission gates 350, 352, 354, 356. Each counter includes a suitable number of flipflop stages, the flip-flop FF2 being an A.M./P.M. stage, and the input to the counters being applied via a lead 286 to a terminal 5 and FF1 from a "carry out" terminal 12 of the time computer. A strobe signal (512 Hz) is applied at calender circuit terminal 12, Fig. 3 and is sub-divided in FF16 FF17 to give appropriate signals at outputs S 1 ', S 2 ', S 3 ', S 4 ' of NOR gates 337 to 340. These signals are applied to correspondingly labelled leads of the respective transmission gates 350, 352, 354, 356. Outputs from these gates pass through OR gates 333 to 336 to the BCD output terminals 1 to 4 of the calendar computer. Flip-flops FF10 to FF14 form a month counter and a system of gates 307 to 318 controls the day counters FF8, FF9 and FF4-FF7, to count 29, 30 or 31 days. Calendar setting arrangements are described. Display intensity control 144 Fig. 3 is provided, using a photo-resistor 146 on the watch face. The switches are reed switches and are operated by permanent magnets on their respective pushbuttons. The hour and minute setting switches are preferably operated by separate permanent magnets manually applied from outside the watch.