| 摘要 |
PROBLEM TO BE SOLVED: To obtain the ringer device for the radio telephone set which has no power source by extracting electric power induced with a sent radio wave at the termination time of the radio telephone set by a tuning circuit and a double voltage rectifying circuit connected to a copper foil antenna which is connected closely to the radio telephone set. SOLUTION: The copper foil antenna 3 provided on a circuit board on which the components of the ringer device are mounted is placed almost in contact with the radio telephone set 10. The tuning circuit 4 connected to the copper foil antenna 3 tunes to a sent radio wave responding to the termination of the radio telephone sets 10 induces a resonant current flowing in itself. Part of this induced electric power is boosted by a transformer 5 and led out by the double voltage rectifying circuit 6 composed of a capacitor C and diodes D1 and D2. A notification circuit 7 includes, for example, an LED lamp, etc., and operates with the DC electric power led out by the double voltage rectifying circuit 6. Consequently, a termination display of a radio telephone device 10 can be made without any electric power, and there is not the possibility that termination notification is disabled unlike before since the user is not aware that the battery is flat. |
