Victor Company of Japan, Limited

Eiichi Kotake

Kinzo Wada

Ken Enami

Naoki Akiyama

Kenichi Kitamura

A tachogenerator has a magnetoresistance film coil formed on a stator surface along a circular path concentric with a rotor axis. The coil has a spatially periodic structure, with multiple spaced-apart lateral components series connected with longitudinal components. The stator surface is opposite to a rotor surface having multiple equiangularly spaced magnetic pole faces with alternately opposite polarities. Current passed through the coil develops voltage variations. Undesirable small voltage variations resulting from manufacturing tolerances are averaged to zero at the coil output terminals.

Tachogenerator having a magnetoresistance stator coil

A rotation control device causes a disc on which information and sync signals are recorded to rotate at a predetermined speed. The control device includes a generator for generating a signal whose frequency is identical with that of a rotation signal which will be output from a frequency generator while the disc rotates at the predetermined speed. A control loop is defined which compares a phase of an output of the signal generator and a rotation signal output from the frequency generator, thereby controlling the drive of the motor.

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Fujieda, Japan

Eiichi Kotake