| 摘要 |
PURPOSE:To reduce the time for judgement of the key collation by changing the frequency from a signal generating means, detecting the time from the start of the change to the detection the resonance frequency, and driving the engine when the detecting time agrees with the set time. CONSTITUTION:Rotor coils 24, 26 are coiled around a core 22 arranged on the circumference of a key inserting hole 12. A resonance frequency detecting circuit 39 detects the generation of the resonance by the voltage drop of a resistor 28 connected to the rotor coils 24, 26, and supplies the stop signal to a timer circuit 50. The timer circuit 50 inputs the signal of the started oscillation to be supplied from a microcomputer 52 to a variable frequency oscillator 30 as the start signal, and starts the counting of the clock signal from a clock signal generating circuit 41. This counting is maintained until the stop signal is received, and this counting signal is compared with the reference signal which is set and stored in ROM, and when two signals agree with each other, the signal to permit the engine drive is outputted. That means, the resonance frequency is not read as a numerical value, and the time for judgement is reduced. |
