Patent ID: 6140781
Filing Date: 2000-10-31
Classification: H02K,H02P

Abstract:
A control method for driving a head drum assembly of a video cassette recorder, said method comprising the steps of:(i) providing a test current to each of magnetic coils having a phase thereof in an initial halt state of a motor of a head drum assembly while an operating mode is set for a video tape recorder;(ii) generating an impulse detection signal while a displacement of a hall sensor is produced with respect to magnetic fluxes generated from impulse generation magnets installed on N and P magnetic poles alternately disposed and included in a plurality of frequency generator magnets installed on an inner peripheral surface of a frame of a rotor included in said motor, and detecting an initial switching position of said rotor based on the impulse detection signal;(iii) comparing a zero-crossing signal obtained by executing a zero-crossing detecting process with respect to the impulse detection signal generated in step (ii) with a count signal obtained by counting a pulse number of the impulse detection signal, determining a next drive order of switching means for driving said motor with reference to a present position of rotary magnets of said rotor, and computing a signal for controlling a rotational speed of said motor based on a determined drive order;(iv) judging whether both the determination of the drive order and the computation operation of the rotational speed of said motor currently proceeding in step (iii), are completed or not; and(v) supplying providing an exciting current to a relevant magnetic coil installed in a stator of said motor in accordance with the drive order determined in step (iii) when it is judged in step (iv) that both the determination of the drive order and the computation operation of the rotational speed control signal are completed, and controlling the rotational speed of said motor to a predetermined speed based on the rotational speed control signal computed in step (iii).