| 摘要 |
PURPOSE: To prolong the service life of a battery as a power source by switching the level of an infrared output corresponding to a distance between a transmission circuit and a reception circuit concerning the transmitter/receiver to perform infrared communication. CONSTITUTION: When the side of the reception circuit is disconnected from the side of a transmission circuit 1, a signal at a low level is outputted from a terminal 4 of an MPU part 3 at the transmission circuit 1, and a PNP transistor Tr 1 is turned on. When a transmitting signal at a high level is outputted from a terminal 5 of the MPU part 3, a field effect transistor(FET) 1 is turned on. At such a time, a current I (V/[(R1.R2)/(R1+R2)]) flows to an infrared LED 1. When the side of the reception circuit is mounted on the side of the transmission circuit 1, the high level is outputted from the terminal 4 of the MPU part 3. Thus, the PNP transistor Tr 1 is turned off. Then, when the FET 1 is turned on, no current flows to a resistor R1 so that a current 1 (V/R2) flows to the infrared LED 1. |
