GB1397667A - Electric clocks - Google Patents

Abstract

1397667 Clocks SONY CORP 21 Feb 1973 [26 Feb 1972] 8431/72 Heading G3T A digital electric clock comprises a D.C. motor 21 which is supplied intermittently from a cell 51, Fig. 4, via a semi-conductor switch 50, the latter switch being controllable by a magnet-sensitive switch, e.g. a reed switch, 22, the control magnet 38 of the switch 22 being displaceable by rotation of the motor 21 so that when the switch 50 is closed by a pulse at electrode b, the motor is energized and displaces the magnet to hold the switches 22 and 50 closed until the motor has advanced the time indicating means 13-15 by one digit only. After this advancement, a cam 42 driven by the motor displaces arm 39 and thus the magnet 38 away from the switch 22 which is thereby opened, opening the switch 50 to stop the motor. The motor is thus energized only during advance of the display drums, which is stated to conserve battery power. The drums 13-15 show hours and tens and units of minutes, the drums being coupled by pins and pin wheels and the drum 15 carrying a ratchet wheel 19 driven by a pawl (37), Fig.2 (not shown) on an arm 35 which is actuated every minute by a cam 23 driven by the motor. The pulses which close the switch 50 once each minute are derived from a quartz oscillator (55), Fig.5 (not shown) via frequency dividers (56,57). The minute drum 15 carries a heart cam 60 so that depression of a pin 62 resets this drum to zero, the count held in the divider (57) being zeroed at the same time. An arrangement is also envisaged in which both dividers and all the drums may be set to zero simultaneously.