| 摘要 |
PROBLEM TO BE SOLVED: To make the power supply of a peripheral device automatically be in off-state, when it is not necessary to operate or to initialize the internal status of a peripheral device automatically when it is not expected to operate normally. SOLUTION: In a system where a personal computer 100, as a host unit is connected with a printer 200, as a peripheral device through the USB interface for instance, the printer 200 detects the on/off status of power supply and the connection of a USB cable with the personal computer 100 through the monitoring of the voltage of V bus line 170 of USB by a sensor 231 in a USB hardware 230. An initialization and power source control section 221 in the printer 200 initializes the internal status of the printer 200 or turns off a power source circuit 240 of the printer 200 if it is detected that the power source of personal computer 100 is turned off or the USB cable is disconnected. |
