GB1410208A - Time-setter for an electronic timepiece - Google Patents

Abstract

1410208 Electric timepieces CITIZEN WATCH CO Ltd 13 Dec 1972 [13 Dec 1971] 57585/72 Heading G3T An electronic timepiece comprising a drive means and a gear train which couples the drive means to the hands of the timepiece has a handsetting push-button 31, Fig. 1 which controls a heart-shaped cam 5 on a seconds-hand arbour 6, and a notched cam 7 on a minute-hand arbour 8, Fig.4, and a clutch mechanism in the transmission between the arbours 6 and 8 which is arranged to slip when both the seconds and minute hands are set, and not to slip when the seconds hand alone is set. In a first embodiment the drive means is a balance-wheel assembly 24 having a stop cam 24a carrying an impulse pin 24b which drives the gear train consisting of an indexing wheel 22, a sixth wheel 21, a fifth wheel 20 and a fourth wheel 6b which is mounted on seconds-hand arbour 6. Between indexing of the wheel 22 it is positioned by a magnet 23 mounted on a base-plate 1. Upon actuation of button 31, a lever 2 is rotated to release a resilient lever 27 which engages one of two projections 24d, 24e or stop cam 24a, thus stopping the balance wheel with pin 24b clear of wheel 22 so that damage to the balance wheel during hand-correction is prevented. The rotation of lever 2 also rotates levers 9 and 11. Lever 9 contacts the heart-shaped cam 5 to zero the seconds hand, and, providing the end 11a of lever 11 engages in notch 7a of cam 7, the minute hand is also set to zero. During this setting the clutch mechanism, which is constituted by a friction clutch comprising a ring 17 and a disc spring 18, slips. If lever 11 does not engage notch 7a no clutch slippage occurs and the minute hand rotates by less than a half-minute, corresponding to the rotation of the seconds hand as it is set. Notch 7a may correspond to a range of + 4 minutes around zero minutes, and further notches may be provided e.g. at thirty minutes and forty five minutes. In another modification Fig.5 (not shown) cam 7 has peripheral teeth. An embodiment is also envisaged in which the drive means is a Piezo-electrically-maintained tuning fork which carries a feed pawl which drives a ratchet wheel. A stop pawl also engages the ratchet wheel to prevent reverse motion thereof, and during setting both the feed and stop pawls are disengaged from the ratchet wheel so that it is freely rotable. Reference has been directed by the Comptroller to Specification 1347024.