Patent ID: 8274398
Filing Date: 2012-09-25
Classification: G07C

Abstract:
1. A Universal Serial Bus (USB) flash drive, comprising: a quartz meter comprising a scale dial and a dial pointer; a timer operable to count a time value when the dial pointer runs around the scale dial; a storage unit operable to store a file system that records storage capacity information of the USB flash drive; a control unit operable to obtain a current storage capacity and a previous storage capacity of the USB flash drive according to the storage capacity information, calculate a storage capacity difference between the current storage capacity and the previous storage capacity, calculate a runtime of the dial pointer according to a time calculation algorithm when the dial pointer points to a mark of the scale dial corresponding to the current storage capacity, generate an enabling signal if the storage capacity difference is not equal to zero, and generate an interrupt signal when the runtime equals the time value; and a logic circuit operable to output a high voltage to the quartz meter to control the dial pointer to run around the scale dial when the enabling signal is received from the control unit, and output a low voltage to the quartz meter to control the dial pointer to stop running on the scale dial when the interrupt signal is received from the control unit.