Citizen Watch Company, Ltd.

Citizen Holdings Company, Ltd.

Takushi Hagita

Akira Kato

Akinari Takada

Tadashi Yasuoka

Provided is a satellite radio-controlled watch, which is capable of holding back a receiving operation when in a posture that does not allow normal reception of a satellite signal, and is capable of performing a receiving operation under conditions varied to suit the type of reference information to be obtained. The satellite radio-controlled watch includes: a reception circuit () for receiving a satellite signal; and a controller () for sequentially detecting a received light amount of the satellite radio-controlled watch, calculating a received light variation which is an amount of change of the received light amount, and controlling the reception circuit () to start an operation of receiving the satellite signal, based on the received light variation. Alternatively, the controller () stores a condition for activating the reception circuit in order to obtain the reference information, in association with each piece of the reference information, and determines, when each piece of the reference information is obtained, whether or not the activation condition stored in association with each piece of the reference information is satisfied, and then controls the reception circuit () to start an operation of receiving the satellite signal, based on a result of the determination.

Satellite radio-controlled watch

A radio-controlled wristwatch that determines whether or not illuminance of light irradiating a solar cell is high, using plural criteria but without directly measuring voltage or current. The wristwatch includes: a solar cell; a control circuit which stops operation under a predetermined condition; and an illuminance detection circuit which indicates illuminance of light irradiating the solar cell being higher than a given threshold value. The wristwatch switches the given threshold value between a first and a second value, larger than the first value, starts the control circuit in a stop state when a signal indicating that the illuminance is higher than the first value is output, receives a satellite signal containing time information from a satellite when a signal indicating that the illuminance is higher than the second value is output, and displays time corresponding to the time information contained in the received satellite signal.

Radio-controlled wristwatch

Provided is a radio-controlled wristwatch that receives a radio wave including day-related information from a satellite within a global positioning system, in which a cycle number of the day-related information is correctly updated even in a case where a power supply voltage drops. A radio-wave wristwatch () according to the present invention includes: reception means () for receiving a radio wave from a satellite and extracting day-related information therefrom; timekeeping-circuit halting means for halting an operation of a timekeeping circuit based on a power supply voltage; timekeeping-circuit halt detection means for detecting that the operation of the timekeeping circuit () has been halted by the timekeeping-circuit halting means; a nonvolatile memory () for storing the day-related information and a cycle number of the day-related information; and cycle-number updating means for updating, when the timekeeping-circuit halt detection means detects that the operation of the timekeeping circuit has been halted, the cycle number of the day-related information based on a comparison result between the day-related information extracted by the reception means () and the day-related information stored in the nonvolatile memory ().

Provided is a radio-controlled watch capable of performing leap second correction even when information on a leap second is not received from a satellite. Provided is a radio-controlled watch that adjusts time by receiving a signal containing time information from a satellite, the radio-controlled watch being configured to: store a leap second correction value to be used for leap second correction with respect to the time information; display a numerical value corresponding to the leap second correction value; receive an instruction operation of changing the leap second correction value from a user in a state in which the numerical value is displayed; and change the leap second correction value in response to the received instruction operation.

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Tokorozawa, Japan

Takushi Hagita