Timepiece movement with differential gear mechanism
AssigneeETA A.G. Ebauches-Fabrik
InventorPierre-Alain Vuille
Life of this patent
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Abstract
In a timepiece movement, more particularly a quartz wrist watch movement, having a low-torque stepping motor, there is provided a differential mechanism which drives the hands and makes it possible to move the hour-hand alone in jumps. A cannon-pinion having a toothing acts as a sun gear. A planet gear is mounted on an hour-wheel which acts as a planet carrier. A ring gear takes the form of an annulus having internal teeth which is normally stationary but is controlled by a stem and can be rotated by jumps to cause the planet gear to roll along the cannon-pinion toothing, thus causing the planet carrier and consequently the hour hand to jump.
Claims6
A timepiece movement having hands and comprising a differential gear mechanism controlling the position of an hour-hand and means for controlling said mechanism, said mechanism in turn comprising a planetary carrier, planet gear means having two coaxial sets of teeth, a sun gear, and a ring gear, said planet gear means engaging said ring gear and said sun gear, wherein said planetary carrier is designed as an hour-wheel, said sun gear is designed as a cannon-pinion having a toothing, and said ring gear is an annulus having internal teeth encircling the path of said planet gear means and connected to said means for controlling said mechanism.
Dependencies are inferred from the claim text.