| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a power source controller for a universal serial bus(USB) capable of supplying power from host equipment when the power source of a printer is turned off and enabling power supply to equipment as well even in an off-state of the printer. SOLUTION: When the power source of a printer 6 is turned on, power is supplied from a printer power source part 8, a driving current flows to relays RL1 and RL2, the contact of the relay RL2 is turned on, and power on the side of the printer 6 is supplied through transistors Q1-Q3 to connected equipment. When the power source of the printer 6 is turned off, power supply from the printer power source part 8 is cut off, the supply of the current to the relays RL1 and RL2 is stopped, and power is supplied from the side of a USB cable to the connected equipment by turning on the contact of the relay RL1. Through such control, while the printer 6 is driven, power is supplied from the side of the printer 6 to the equipment but while the printer 6 is not driven, power can be supplied from the side of the USB cable.</p> |
