Patent ID: 7079451

Claim:
A time measurement device, comprising: power generating means for generating power from energy coming in from the outside; power storage means for storing the power generated by the power generating means; current time information storage means for counting the passage of time; receiving means for receiving a radio wave bearing time information; time display means for displaying the current time; power detecting means for outputting a power detection signal when the power generating means is in a power generating state or when the magnitude of a voltage stored in the power storage means is not less than a predetermined voltage magnitude; and operation mode switching means for switching, in response to the power detection signal output from the power detecting means, between a power saving mode in which the time display means is maintained in a suspended state and a standard mode in which the time display means is maintained in an active state; wherein in response to the device being switched from the power saving mode to the standard mode, the operation mode switching means causes the receiving means to receive the time information and causes the time display means to display the current time based on the time information counted by the current time information storage means and the time information received by the receiving means.