Patent ID: 7307919

Claim:
A radio-controlled timepiece comprising: a reception means for receiving time information modulated by rectangular wave pulses; a reception control means for controlling driving the reception means based on a preset schedule; a time information updating means for updating internal time information, based on the time information received by the reception means; a time adjustment storage means for storing how much the internal time information was adjusted by the time information updating means; and a time display means for displaying the time based on the internal time information; wherein the rectangular wave pulses have a rising edge or falling edge occurring at a one-second interval and have a pulse width that when measured from a reference timing that is the timing of the rising edge or falling edge of a pulse to the falling edge of a pulse that rose or the rising edge of a pulse that fell is less than the one-second interval and is one of a plurality of lengths; the reception control means comprises a simple time adjustment means that is driven when the reception means is driven within a predetermined time of the last successful signal reception, and a normal time adjustment means that is driven when the reception means is driven after a predetermined time since the last successful signal reception has passed; the normal time adjustment means drives the reception means for the time required to receive a full time code, and adjusts the internal time information by means of the time information updating means when time code reception is successful; and the simple time adjustment means comprises a pulse timing detection unit for driving the reception means for a shorter time than when receiving a full time code and detecting the reference timing of the rectangular wave pulses in the time information, an offset calculation unit for calculating the offset between the reference timing of the rectangular wave pulses detected by the pulse timing detection unit and the timing of seconds in the internal time information, an offset evaluation unit for determining if the offset calculated by the offset calculation unit is within a tolerance range set based on the previous time adjustment stored in the time adjustment storage means, and a seconds information adjustment unit for adjusting seconds information of the internal time information based on the offset when the offset evaluation unit determines the offset is within the tolerance range.