Hitachi, Ltd.

Aisin Seiki Company, Ltd.

Kosho Ishizaki

Hiroshi Kimura

Shigeki Morinaga

Kunio Miyashita

Hiroshi Hayashida

Katsutoshi Nii

Kazuhiko Kawaike

Giichi Ishida

Satosi Uno

Sueo Akashi

Hiroo Hiroyama

Takeo Maeda

Ichiro Hashimoto

Yuukou Nojiri

Junshiro Inamura

Kaneharu Kuzuya

A motor provided with a magnetic fluid bearing device for suppressing vibration and irregular rotation as well as preventing the magnetic fluid from being scattered from a bearing portion and the inside of the motor. The motor includes a rotor having a polygon mirror mounted thereon, a stator unit having driving coils, a rotor position detector and a rotor revolution detector attached thereto, a magnetic fluid bearing unit having a magnetic seal and a dynamic pressure seal attached thereto and a magnetic bearing. A triple seal structure for magnetic fluid which includes a first fluid seal constituted by the seals of the bearing unit, a second fluid seal constituted by a magnet of the rotor and a third fluid seal constituted by a magnet of the seal magnet is provided in the motor.

Sealed magnetic fluid bearing for polygon mirror drive motor

A motor with a magnetic fluid bearing for suppressing vibration and irregular rotation as well as preventing the magnetic fluid from being scattered from a bearing portion in the inside of the motor. The motor includes a rotor having a polygon mirror mounted thereon, a stator unit having driving coils, a rotor position detector and a rotor revolution detector attached thereto, a magnetic fluid bearing unit having a magnetic seal and a dynamic pressure seal attached thereto and a magnetic bearing. A triple seal structure for magnetic fluid which includes a first fluid seal constituted by the seals of the bearing unit, a second fluid seal constituted by a magnet of the rotor and a third fluid seal constituted by a seal of the magnetic magnet is provided in the motor.

A large number of teeth are formed on the outer circumference of a rotor. A stator is disposed around the rotor. The stator has multiple magnetic poles whose number is n times the number of phases. Each pole has formed on its surface a plurality of teeth at a pitch equal to the rotor tooth pitch. The teeth mounted on the adjacent magnetic poles are selected to deviate in pitch one-half or thereabout from the rotor teeth and the adjacent poles are to be opposite phases from each other.

Low-speed high-torque motor

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

An endless counting apparatus comprises a first memory for storing a code of a first predetermined number of bits sufficient to represent the maximum value of each coded input expressed according to the binary notation, a second memory for storing an endless-making code of a second predetermined number of bits of higher order than and contiguous to the less and least significant bits stored in the first memory, and a control circuit for adding or subtracting the value of the coded input to or from the contents of the first and second memories depending on the input value to be counted and applying the result of addition or subtraction to the first and second memories. A method for endless counting by such an apparatus comprises clearing the most significant bit of the endless making code stored in the second memory when the code stored in the second memory has attained a value which causes an overflow due to a carry from the contents of the first memory if the carry occurs, and setting the most significant bit of the endless-making code stored in the second memory when the code stored in the second memory has attained a value which causes an underflow due to a borrow from the contents of the first memory if the borrow occurs.

Method and apparatus for counting an infinite length with a counter of

A method and apparatus for controlling the angular position of a motor by controlling the revolution of the motor in response to a given positioning command value commanding a predetermined angular position of the motor shaft so as to stop the motor shaft at the predetermined angular position, wherein the acceleration of the motor being accelerated in the initial acceleration stage of the motor position control operation is calculated, and on the basis of the calculated acceleration and a commanded maximum velocity, the remainder angular distance between the deceleration starting angular position and the desired angular position of the motor and the deceleration command value in the deceleration stage are calculated so as to control the deceleration of the motor on the basis of the calculated values.

Method for controlling angular position and apparatus therefor

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

An apparatus for controlling an electric sewing machine has a mechanism for transmitting the driving torque of a motor to the sewing machine to drive the same, a mechanism for imparting braking power to the sewing machine to stop the same, a mechanism for stopping the needle of said sewing machine at desired positions in its stroke and controlling means adapted to control these mechanisms. At least a part of the controlling means is constituted by a microcomputer. The signal input to the microcomputer is provided in synchronization with a synchronizing clock signal, and only such input signals as required in respective periods of operation are checked in each of the periods, so that the checking of the input signals is facilitated and accidents due to erroneous operation are avoided.

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Hitachi, Japan

Kosho Ishizaki