| 摘要 |
PURPOSE: To judge the state of using/not using a device without using any special mechanical switch and to easily suppress power consumption according to that state. CONSTITUTION: When there is an optical input, a photodiode 5 for light reception generates a photoelectric current IL to be changed corresponding to its luminosity L and sends that photoelectric current IL to an operational amplifier 6. When the photoelectric current IL is received, the operational amplifier 6 generates an output voltage Vo. A voltage detection circuit 8 detects the output voltage Vo from the operational amplifier 6 and sends the result to a power management controller 10. Based on the output result from this operational amplifier 6, the power management controller 10 judges the usual using state/not using state of this device. |
