Seiko Clock Inc.

Koji Baba

Hiroyuki Hashizume

Katsuhiro Hatano

A timepiece movement comprises a first luminous element for emitting light, a second luminous element for emitting light, and a light-receiving element for receiving the light emitted by the first and second luminous elements. A second wheel has an aperture through which light from the first luminous element may pass and a reflecting portion. A first transmitting wheel transmits a rotational drive to the second wheel as a function of second time and has an aperture through which light from the first luminous element may pass and which is positioned to become aligned with the aperture of the second wheel. A rotational minute wheel has apertures disposed at equal angular intervals and through which light from the second luminous element may pass. A rotational hour wheel has apertures through which light from the second luminous element may pass. Each of the apertures of the hour wheel are positioned to become aligned with respective ones of the apertures of the minute wheel during rotation of the minute and hour wheels. A second transmitting wheel transmits a rotational drive to the minute wheel and the hour wheel as a function of minute time and hour time, respectively. The second transmitting wheel has a plurality of apertures disposed at equal angular intervals and through which light from the second luminous element may pass. The apertures of the minute wheel are positioned to become aligned with respective ones of the apertures of the second transmitting wheel during rotation thereof.

Timepiece movement

A timepiece movement comprises a light-emitting device for emitting light and a light-receiving device for receiving the light emitted from the light-emitting device. An hour wheel has a plurality of apertures through which light from the light-emitting device may pass. A minute wheel has an aperture through which light from the light-emitting device may pass, the aperture being positioned to become aligned with respective ones of the apertures of the hour wheel during rotation of the minute and hour wheels. Minute and hour wheel gear trains respectively rotate the minute wheel and the hour wheel as a function of minute and hour time.

A viscous coupling gear device has a first case having a protrusion extending from a surface thereof, and a second case having a surface facing the surface of the first case and a protrusion extending from the surface of the second case. A gear has a driving portion for driving engagement with a first rotary member undergoing intermittent rotation and for transmitting intermittent rotation to the gear, a tubular portion extending from the gear and mounted on the protrusion of the first case for relative rotation therewith, and a tubular wall portion extending from the gear and disposed coaxially with and spaced from the tubular portion to define a cavity therebetween, the protrusion of the second case extending into the cavity and defining, together with the cavity and the tubular wall portion, a clearance. A driving member engages with a second rotary member for transmitting rotation of the gear to the second rotary member. A viscous fluid is disposed in the clearance for absorbing a velocity variation due to the intermittent rotation of the first rotary member so that the driving member transmit a smooth and continuous rotary motion to the second rotary member.

Viscous coupling gear device

A timepiece movement comprises a rotor driven for intermittent rotation by a stepping motor, a speed-reducing wheel train and a second stop device. The speed-reducing wheel train has a movement conversion mechanism for transmitting intermittent rotary movement of the rotor to continuous rotary movement of a second hand wheel in a smooth manner. The second stop device is moveable between a first position, for immediately stopping the second hand wheel, and a second position, for immediately moving the second hand wheel at a predetermined speed.

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Tokyo, Japan

Koji Baba