| 摘要 |
PURPOSE:To realize a battery saving by judging with a receiving input electric field level or receiving data whether the battery exists at either inside or outside the service area and turning on or off the power source of respective circuits periodically outside the area. CONSTITUTION:A receiving electric field strength is detected by a transmitting/ receiving part 2 and sent to an out-of-range detecting circuit 5 as an RSSI signal 13 converted to a direct current component. By a voltage comparing circuit in the circuit 5, it is judged whether the battery is lower or higher than the voltage of the RSSI signal necessary at the minimum as a service area, when it is lower, a low level signal 1 2 is supplied and when it is higher, a high level signal 12 is supplied to a battery saving circuit 6. At the circuit 6, when the signal 12 is a high level, the power source is always supplied to the transmitting/receiving part 2 and a control part 3, and when the signal 12 is the low level, the power source supply is periodically turned on or off. |
