RECORDER MIT ANTRIEBS-PHASENDETEKTOR

摘要

Integrated motor circuits for controlling electronically commutated motors driving head drums are known which include means of obtaining tacho-signals for the motor speed control and means of obtaining control signals for commuting the motor phase belts. These signals are obtained by commutation by the detection and evaluation of the transitions through zero of the induced countervoltages when the phase belts are switched off. However, the precision of the motor drive is determined by the manufacturing tolerances on the motor. For high-precision motor drives in recording and playback instruments, therefore, a phase regulation derived from markings on the rotating parts is also used. The aim is to reduce the complication of phase detection of the read/write heads fitted at the periphery of a rotating head drum in a circuit for regulating the head drum and tape drive. In an electronically commutated head drum motor (3) fitted with a motor control circuit (32) generating commutation control and tacho-signals from the commutation of the phase belts (X, Y, Z) of the motor (3), in order to detect the phase of the read/write heads (K1, K2) arranged at the periphery of the rotating head drum (1), one of the phase belts (X, Y, Z) is used by deriving from the commutation of this phase belt a commutation signal (I) which is placed in a relationship with the reference signal (20) of a signal track to be recorded or played back. Especially for video recorders and camcorders.