| 摘要 |
PURPOSE:To extend the service life of a battery by saving power consumption. CONSTITUTION:An output of a light receiving circuit 7 is at a low level when the surrounding is bright, a switch element 263 is conductive and a switch element 202 is nonconductive. Thus, an output 204 of a light emitting element use power supply and a light emitting element 8 are directly connected, the light emitting element 8 receives the power supplied by the output 204 of the light emitting element use power supply as it is and is lighted. When the surrounding is dark on the other hand, an output of the light receiving circuit 7 goes to a high level, the switch element 202 is conductive and the switch element 203 is nonconductive. Thus, a resistor R is interposed between the output 204 of the light emitting element use power supply and the light emitting element 8 and the light emitting element 8 receives the power supplied by the output 204 of the light emitting element use power supply while a voltage drop by the resistor R is received and is lighted weakly. That is, the current consumption is saved. |
