| 摘要 |
PURPOSE:To prevent erroneous measurement by generating a characteristic delay signal longer than the scan signal pitch of a microcomputer with performs speed arithmetic when a speed is high and the width of a waveform-shaped speed pulse is short. CONSTITUTION:A speed detection signal from the speed sensor 1 for a bicycle, etc., consisting of a rotating magnet 3 and a Hall element 5 is shaped by a waveform shaping circuit 8, and a microcomputer 10 controlled by a prescribed scan signal calculates a speed. When the bicycle runs fast and the width of a speed pulse is narrow, a characteristic delay pulse from a timer which has a little bit wider width than the interval of the scan signal outputted by a monostable circuit of a delay setting time constant part of a resistance R1, a capacitor C1, etc., and a circuit 8 of the timer 9, etc., is applied to the computer 10. When the speed is low and the width of the speed pulse is long, the circuit 8 never has a monostable phenomenon and the speed pulse is applied as it is to the computer 10, thus obtaining a speed indicator which prevents malfunction even during a high-speed run. |
