| 摘要 |
The control mechanism for the hours and minutes display on a wrist watch includes a balance wheel (15) acting under the effect of a spring, via an ratchet wheel (18) on a cam (12) situated at the centre of the movement. This in turn is linked to the hour hand. The balance wheel (15) is lifted up progressively under the effect of the cam (12), to fall back suddenly once per hour. When the wheel makes these sudden drops, a toothed sector (23) engages a central pinion via a drive chain (24,25,26), the central pinion carrying the minute hand. Thus once per hour the minute hand is returned to its original position. The balance wheel is also linked to a pawl (30) co-operating with a star wheel with twelve branches carrying a disc indicating the hours. |
