Victor Company of Japan, Limited

Yukimi Hirose

Makoto Itonaga

Kinzo Wada

Ken Enami

Nobuaki Nakamura

Masakatsu Kai

An optical detection system for detecting a displacement amount of a movement device with an optical encoder movable in accordance with a movement of the movable device has on a light-reflecting layer a plurality of pits successively strung in a predetermined direction. An optical pickup optically picks up the pit information by irradiating the optical encoder with light beams and receiving reflected light beams from the optical encoder. The optical pickup comprises a light-division device for dividing the light beam from a light-emitting device into three light beams so that the divided three light beams are directed to the pit string to apply three light spots to the pit string. The light-division device is adapted to be rotatable with respect to the optical encoder so that a light passing through the three light spots intersects the pit string at a predetermined angle. The reflected light beams due to the outside light spots are respectively incident on two photosensitive elements each generating an electrical signal. The electrical signals from the photosensitive elements, which are out-of-phase by an amount corresponding to the rotation of the light-division device, are fed to a detection circuit to detect information of the movement of the movable device and produce a pit detection signal indicative of the information.

Detection system with an optical encoder to optically detect

A commutatorless electrical motor comprises a cylindrical magnetic rotor having main magnetic poles where N and S poles are alternately arranged in the circumferential direction, and an axis of N and S poles of each magnet extends radially, and a sub magnetic poles at one end of the cylindrical rotor. The sub magnetic poles are arranged such that N and S poles of each magnetized area extends axially. The magnetized area providing each sub magnetic pole has an arcuate extent of .pi./2 or less in an electrical angle. Each of the magnetized area providing each sub magnetic pole makes a given change in the magnetic flux density distribution in the vicinity of rotational position detecting elements so that the rotational position of the rotor can be accurately detected. As a result, current switching circuit for changing over armature currents will be controlled by the accurate information from the detecting elements, and thus each armature winding will be energized in a desirable manner, reducing undesirable torque ripple.

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Fujieda, Japan

Yukimi Hirose