Hitachi, Ltd.

Aisin Seiki Company, Ltd.

Giichi Ishida

Kosho Ishizaki

Ichiro Hashimoto

Masayoshi Sunada

Koujirou Yamashita

Yuukou Nojiri

Junshiro Inamura

Kaneharu Kuzuya

A step motor which comprises a stator having a winding wound therearound, a rotor rotatably provided with respect to the stator, a multiplicity of pole teeth formed on mutually opposing faces of the stator and rotor, a position detector for detecting a position of the rotor, and switching means for changing over a phase current flowing through the winding wound around the stator on the basis of a position signal indicative of the position of the rotor, wherein the pole teeth and a position detectable portion are integrally formed on a rotary yoke of the rotor and the position detectable portion is detected by the position detector. A method for recording a position signal of the rotor in the step motor, wherein, when the position detectable portion is made in the form of a magnetic recording medium, the pole teeth are formed on a predetermined surface of a rotary yoke of the rotor, a magnetic recording medium is provided on a surface of the rotary yoke which is not provided with the pole teeth, and a position detecting signal is magnetically recorded on the magnetic recording medium with respect to a reference position of the pole teeth.

Step motor and method for recording position signal of motor rotor

A cylindrical field system of a low speed high torque motor is divided in an axial direction into first and second field system portions, these two field system portions are connected by a connecting member and a field magnet is disposed between the field system portions so that particularly machine work can be made before fitting of the field magnet. Accordingly, chips can be removed easily by use of a simple device. A cylindrical field system is divided in an axial direction into first and second field system portions, these field system portions are connected by a connecting member and cylindrical magnets fixed to a flexible belt-like fixture are wound on the field system portions between them so as to produce a rotor. Accordingly, the assembling property of the motor can be improved remarkably.

Low speed high torque motor with production method

The present invention provides method and apparatus to control a plurality of DC motors each having an encoder by a sole microcomputer. The actual rotating speed of each DC motor is detected in response to the signal from the encoder. A pulse width of a voltage which is applied to each motor is controlled due to the deviation between the actual speed and a preset speed. The output signals from the encoders regarding a specific DC motor to the other DC motor are sequentially selected by a selection signal, thereby controlling the speed measurements and calculations regarding a plurality of DC motors and the duties of electric powers which are applied to the DC motors.

Method of and an apparatus for controlling a plurality of DC motors

A stitch pattern setting apparatus for an electrically driven sewing machine comprises at least two pattern setting units each including stitch pattern selecting arrangements for selecting a desired one of a plurality of different stitch patterns and pattern setting arrangements for setting the numbers of stitches, respectively, for pattern elements constituting the selected stitch pattern. Each of the pattern setting unit is capable of selecting the stitch pattern and setting the stitch numbers independent of the other pattern setting unit.

Stitch pattern setting apparatus for electrically driven sewing machine

In a control circuit for controlling the rotating speed of a clutch and brake motor of a sewing machine capable of performing non-ravel seaming, an improved non-ravel seaming controller for enabling non-ravel seaming during a certain number of seams at the start of sewing and for generating a medium speed signal at a predetermined level during a certain number of seams at the end of sewing to enable non-ravel seaming at such time.

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Hitachi, Japan

Giichi Ishida