| 摘要 |
PURPOSE:To allow highly accurate speed control by controlling the driving amount with a speed control voltage being increased or decreased based on the time difference between the period of a speed detection signal of a motor and a time reference thereby feedback controlling the speed. CONSTITUTION:At the time of low speed operation where the rotational speed of a motor 22 is lower than a reference level, the period of a speed signal Vf elongates and the H interval of a speed pulse signal V2 becomes longer than a time pulse signal Vt. Consequently, a first error pulse signal V31 having pulse width corresponding to the time difference is outputted to increase the speed control voltage Vcp. At the time of high speed operation, the period of the speed signal Vf is shortened and the H interval of the speed pulse signal V2 becomes shorter than the time pulse signal Vt. Consequently, a second error pulse signal V32 having pulse width corresponding to the time difference is outputted to decrease the speed control voltage Vcp. Rotational speed of the motor 22 is feedback controlled to equalize the speed pulse signal V2 and the H interval of the time pulse signal Vt. This constitution allows highly accurate speed control using a circuit having relatively small number of elements. |
