| 摘要 |
<p>PURPOSE:To simplify the structure of a transmitter provided on a key. CONSTITUTION:A key detecting switch, a primary coil 14, a photo-diode 16, and a transmission/reception judging circuit 17 are provided on an ignition key cylinder 2. A light emitting diode 22 and an oscillating circuit 20 constituted of a secondary coil 19 and a capacitor 21 are provided on a key 5. When the key 5 is inserted into the key cylinder 2, the primary coil 14 is excitation- controlled, the induced electromotive force is generated on the secondary coil 19, the oscillating circuit 20 is oscillated, and the light emitting diode 22 emits a light signal based on the oscillation. The light signal is received by the photo- diode 16. The transmission/reception judging circuit 17 allows the operation of an EFI 18 only when it judges that the received signal is a specific signal. A transmitter is constituted of the oscillating circuit 20 and the light emitting diode 22, and the structure of the transmitter can be made simple as compared with that emitting the radio signal.</p> |
