| 摘要 |
PURPOSE:To eliminate the need for an IC for serial-parallel conversion and to shorten the time required for the conversion and also to eliminate malfunction which is caused by a noise by controlling the illumination of a blank lamp with a PWM signal. CONSTITUTION:The PWM signal (pulse width - modulated signal) sent out of a control means 21 is sent to an integration circuit 22 and converted into a voltage signal which varies linearly with the pulse width. A lamp driving circuit part 23 is constituted by connecting series circuits of comparing amplifiers and lamps in parallel, and the voltage signal for control which is obtained through the conversion of the integration circuit 22 is applied to the positive side terminals of the respective comparing amplifiers and a reference voltage is applied to the negative side terminals, so that lamps whose number corresponds to the input voltage signal illuminate. Consequently, data for the illumination control can be sent at a time and the need for the IC for serial- parallel conversion is therefore eliminated; and the time spent for the conversion is shortened and no conversion part is provided, so malfunction which is caused by noise is eliminated. |
