| 摘要 |
PURPOSE:To quicken the response, by heightening accuracy by lengthening the gate pulse width in idling time and shortening the gate pulse width in traveling time in an engine tachometer. CONSTITUTION:The pulse of frequency proportional to the number of revolutions of engine is outputted by a rotating number detector 1 and this pulse is passed through a gate circuit 3 by a time width of gate pulse outputted from a gate pulse generating circuit 2 and is multiplied by a frequency multiplyier 4. Then, said pulse is counted by a counter 5 and is digitally displayed by a display device 7. At this time, when the number of revolutions is a prescribed value or more (traveling time), the width of the gate pulse is shortened by driving a gate pulse alteration circuit 9 by the output of a detecting circuit 8 and also the frequency multiplying ratio is increased in accordance with this shortening ratio. Thus, a highly accurate display is made in idling time because the gate pulse width is long as it is and on the contrary, a response time of display is shortened in traveling time. |
