An electronic timepiece comprising a means for generating a base signal, an electromechanical transducer to convert the base signal into mechanical motion of a rotatable shaft, only a back side chain of wheels and a driving means whereby the back side chain of wheels is directly driven by the rotatable shaft. Furthermore, the driving means is coupled to the rotatable shaft such that idling rotation of the driving means occurs without rotation of the rotatable shaft when the timepiece is being set externally.
A movement structure for an analog display type electronic watch powered by a coin-shaped lithium cell. The movement structure comprises a base plate of a synthetic resin. The base plate has an integral lug portion which engages with and support the battery cell in a fixed place.
A stepping motor driven by a time-based electrical driving signal periodically rotates an overhung gear train directly driving the hour and minute hands mounted on a main arbor. The arbor is rotatably mounted in two spaced journals in a single tapered bearing hole in the frame. An intermediate arbor is similarly journaled. The gear train is assembled from only one side of the timepiece. The main arbor, center gear assembly, hands and dial are all added as a subassembly.
A thin movement for a stepping motor watch employs a single frame member a peripheral front frame portion surrounding and connected to a back frame portion and stepping motor stator, affixed to the frame member, pins fixed in the back frame portion and stepping motor stator, gear members including the stepping motor rotor and gear train driving the watch hands rotatably mounted on said pins, a dial for the timepiece supported on the front frame portion, the dial serving to control axial movement of the gear members on the pins. Only two layers of gear members are required in the space between the back frame portion and the dial.
In the movement for an electronic watch with analogue display, hand-carrying arbors 20, 22 have pinions 20a, 22a of very small diameter, rather than wheels. The cell 10 has a diameter which is substantially equal to the radius of the movement plate 2, since the cell extends from the periphery of the movement up to the pinions 20a, 22a. The wheels 28, 30, 34, 40, 42 which drivably connect the motor 8 to the pinions 20a, 22a are arranged in such a manner that there is no overlapping between the cell 10 and the wheels. This makes possible a movement which is both of small diameter and thin.
A gear train mechanism for a wristwatch provides a thinner watch, the gear train comprising a frame plate, a dial, a plate interposed between the dial and the frame plate, and a shaft rotatably supporting a center wheel and pinion. The shaft is attached to the frame plate. Rubbing and misalignment of the hands is prevented by aligning their rotating support members for an extended longitudinal distance on the shaft. This is accomplished by the gear train of this invention despite a reduction in the thickness of the watch. Hour and minute hands or hour, minute, and second hands are provided in alternative embodiments.
