Patent GB-1385567-A (GB)
Title: Watches
IPC: G04F5/06
Filed: 1972-06-20
Abstract: 1385567 Electronic watches TIME COMPUTER Inc 20 June 1972 28906/72 Heading G3T A solid state timepiece comprises a crystal controlled oscillator providing timing signals at 32768 HZ to an integrated circuit including - an MOS frequency divider chain, MOS counting registers, and a decoder logic circuit coupling the outputs of the divider to digital electro-optical display devices each in the form of 7-bar segment array of light-emitting diodes (or alternatively a 27 dot matrix of diodes, or incandescent lamps or a liquid crystal, ferro-electric crystal or electroluminescent display). The display indicates hours and minutes on demand for a pre-set period (1“ secs) only or optionally indicates continuously. Seconds are indicated on the same display devices as the minutes digits, if a demand button is maintained pressed. Day and month also A.M. and P.M. may optionally be displayed. Also the time indicating control may be by-passed and the display devices used to display information fed thereto from a source external to the watch. Connections to give alarm indication are also suggested. The light emitting intensity may be varied in dependence upon the ambient light conditions. CIRCUIT OPERATION - (FIGS 5 and 6) - The integrated circuit components of FIG 6 are contained in a block 70, Fig. 5, the crystal 64 and tuning capacitor 66 of the oscillator 26 being external of the integrated circuit. From the oscillator output the divider 30 produces several output frequencies including an 8 Hz output which is fed into a counting register 164 to produce 1 HZ output on a lead 166. This 1 HZ output is fed into counting registers 172, 174, 176, 178, 180 where it is further divided by 10, 6, 10, 6 and 12, corresponding to the digits needed to display seconds, minutes and hours. The binary coded decimal outputs of all the dividers in the registers are fed into respective selection gates 182, 190, 192, 194 and 196. These gates are controlled by a strobe circuit 216 which determines the numeral passing through input gates 184 into a decoder driver 186. A timer 170 controls the strobing circuit 216. When the demand switch 132, Fig. 5, is pressed the strobe circuit selects the register to be read. Since the seconds display does not occur at the same time as the minutes and hours, only four numerals are 'strobed'. Six outputs ABCDEF of the strobe circuit 216 are applied to similarly labelled lines of the selection gates. A second set of strobe outputs S 1 , S 2 , S 3 , S 4 , S 5 , S 6  are applied respectively to the bases of transistors 82, 84, 86, 88, 90, 92, Fig. 5, in the anode circuits of respective display diodes. The decoder 186 converts the binary coded decimal signals of the registers determined by the strobe circuit into suitable drive signals which are applied via buffer amplifiers 188 and via terminals a, b, c, d, e, f, g to the bases of respective transistors 112, 114, 116, 118, 120, 122, 124, in the cathode circuits of respective display diodes of the display devices 76, 74, 80, 78 and colon 81. The colon 81 may be used for A.M., P.M. display INTENSITY CONTROL The strobe drive signal comprises a train of pulses which blink the diodes on and off for example at 6 4 HZ. To control the intensity the pulse width of this signal is varied m dependence upon the incident light falling on the watch display and as sensed by a photo-resistor 146, Fig. 5. Arrangements for fast or slow-rate setting of the hours and minutes is described.