ROTATIONAL SPEED CONTROL METHOD FOR MOTOR, ROTATIONAL SPEED CONTROL DEVICE FOR MOTOR AND RECORDING OR REPRODUCING DEVICE

摘要

PURPOSE: To make an arithmetic processing simple in the recording/reproducing device of a reel drive system. ;CONSTITUTION: Edges of wave form shaped outputs are detected by a detection part 30 and counter clocks (CP) 32 are supplied to a pulse width measuring part 31. Edge detection pulses are supplied to a one rotation detecting part 33 and registers 34A to 34D and shifted. An adding unit 35 generates the addition value E of the disk of registers according to a one rotation detection pulse. A rating rotational period holding part 37 holds the count value F of the same frequency as that of the CP generating part 32 and a dividing unit 36 calculates G=E/F. Next, a multiplying unit 38 generates a modulation rate H by multiplying the ratio G by the present modulation ratio H₁ of a memory 39. The modulation ratio H is supplied to a frequency modulation pulse generating part 40 and to the memory 39 via the terminal T₂ of a switch 42 to be stored as the modulation ratio H₁ of a next calculation. At first, the memory 39 is connected to a terminal T₁ to calculate a first H by multiplying the ratio G by a modulation ratio (G=1) being as an initial value and later is switched to the terminal T₂.;COPYRIGHT: (C)1995,JPO