Patent ID: 7480625

Claim:
A sales data processing device which executes sales data processing by referring to a date and time, comprising: electromagnetic wave clock means for clocking a date and time, for receiving a time signal containing date and time information that is transmitted from a time signal transmission station, and for correcting the clocked date and time based on the received time signal; clock means for clocking a date and time for the sales data processing; processing state determination means for determining whether or not sales data processing is being executed; power source determination means for determining whether the sales data processing device is in an energized state in which power is supplied to the sales data processing device by a main power source, or in a standby state in which power is supplied to the sales data processing device by a secondary power source due to disconnection from the main power source; and selection means for, when the power source determination means determines that the sales data processing device is in the energized state to be operated by the main power source and when the processing state determination means determines that the sales data processing device is in a state of not executing the sales data processing, selecting a time correction method in which the time signal is received at regular time intervals by the electromagnetic wave clock means, and in which the date and time of the clock means is corrected by the correction means based on the time signal received at the regular time intervals.