Citizen Watch Company, Ltd.

Citizen Holdings Company, Ltd.

Takuji Ike

Takayuki Uchida

Akinari Takada

Masaaki Namekawa

Takayuki Hasumi

Isao Kitazawa

Koichi Sato

Teruhiko Fujii

A radio-controlled timepiece includes an oscillator circuit of which an oscillation condition can be varied by an oscillation condition adjustment circuit that adjusts an oscillation frequency, a frequency divider circuit that divides the oscillation frequency and generates a time measurement reference timing signal, a frequency adjustment circuit that adjusts the period of time measurement reference timing signal, a local oscillator circuit that uses the oscillation frequency as a reference frequency and outputs a local oscillation frequency, and a control circuit. The control circuit, when the radio-controlled timepiece is performing reception operations, causes the oscillation condition adjustment circuit to operate whereby the oscillation frequency is adjust to an optimal frequency for the local oscillator circuit and the variation setting value of the frequency adjustment circuit is set such that time measurement reference timing signal has a fixed period for normal operations and for reception operations.

Radio-controlled timepiece

An electronic timepiece includes a limiting circuit that is controlled by the rotation detecting circuit and limits output of a locking pulse PL. The electronic timepiece prevents the display of the incorrect current time due to impact, by executing impact detection when rotation is detected, and prevents errant hand operation in a magnetic field by not outputting a locking pulse PL by prohibiting impact detection when non-rotation is detected. The electronic timepiece controls the limiting circuit using a ranking-down storing circuit and if the electronic timepiece employs multi-stage load correction, executes impact detection when regularly occurring non-rotation is detected. Thereby, errant deviation in the display of the current time due to impact is prevented. The electronic timepiece prohibits the impact detection and causes the locking pulse PL not to be output when non-rotation other than those occurring regularly is detected. Thereby, errant hand operation in a magnetic field is prevented.

Electronic timepiece

An analog electronic watch of the present invention includes: a display unit () for displaying time with a position of a hand; a stepper motor () for driving the hand; a motor drive unit () for controlling driving of the stepper motor at a predetermined hand drive cycle at normal time; hand position detection means () for detecting a position of the hand; a hand position detection means control unit () for intermittently controlling driving of the hand position detection means () at a first detection cycle which is longer than the hand drive cycle; and a detection cycle changing unit () for instructing the hand position detection means () to change the detection cycle. When detecting a predetermined detection cycle changing condition, the detection cycle changing unit () changes a cycle at which the hand position detection means () detects a position of the hand, from the first detection cycle to a second detection cycle, while maintaining the hand drive cycle at which the stepper motor () drives the hand.

Analog electronic watch

Growing community of inventors

Tokyo, Japan

Takuji Ike