Hitachi, Ltd.

Japan Servo Co.,ltd.

Hideki Nihei

Nobuyoshi Tsuboi

Hiroshi Sasaki

Yoshio Sato

Norifumi Miyamoto

Satoshi Shimada

Hiroaki Koyanagi

Hiroshi Kimura

Fumio Tajima

Shigeki Morinaga

Tetsuo Ito

Nobuyoshi Mutoh

Atsumi Watanabe

Hiroyuki Minemura

Kunio Miyashita

Hiroshi Kanazawa

Hiroshi Nagase

Syooichi Kawamata

Hideaki Horie

Ryoso Masaki

Satoru Kaneko

Shiho Izumi

Hiroshi Katayama

Noriaki Hino

Hiromi Inaba

Kanji Kawakami

Yasunori Katayama

Ryo Hiraga

Toshihiko Matsuda

Ryuji Watanabe

Seizi Yamashita

Hideki Asano

Kazuo Ohnishi

Hiroshi Hayashida

Masahiro Kayama

Tsutomu Miyoshi

Shunichi Tanae

Kenzo Kamiyama

Ryoichi Naganuma

Toshiyuki Tadokoro

Ito Tetsuo

Satoshai Shimada

Kouichi Saitoh

When the torque command value is zero, a set point of DC current for an inverter is calculated to obtain a difference between the set point and a detected DC current so that an error in magnetic pole position may be estimated and corrected. By correcting the magnetic pole position, unwanted power running and regenerative torque of the motor can be avoided and unnecessary charge or discharge to or from a battery can be prevented.

Motor controller

The present invention comprises a stator, and a rotor which is disposed oppositely to the stator with a gap interposed. The stator comprises a stator core, and a distributed stator winding mounted to the stator core. The stator core comprises a ring-like yoke core, and a plurality of teeth cores which protrude from the yoke core in the radial direction. The rotor comprises a rotor core, and a plurality of permanent magnets embedded in the rotor core. A pair of non-magnetic portions is created inside the rotor core and on both sides of the circumferential width of a permanent magnet for one magnetic pole. In the rotor core located on the stator side of the pair of non-magnetic portions, a pair of magnetic paths is created as the result of the creation of the pair of non-magnetic portions. Furthermore, a groove or hole is created on the outer circumferential portion of the rotor core and between the adjacent magnetic poles.

Permanent magnet type generator and hybrid vehicle using the same

An elevator system in which an elevator-car and a counter weight are suspended on a pulley system in a hoistway. The elevator system includes a receiving unit for receiving an electric power from a feeding unit provided in the hoistway, an inverter for converting the received electric power into ac power, a motor connected to an ac side of the inverter for driving the counter weight in up and down directions, a sensor for detecting a position of the receiving unit, and a control unit for controlling an inverter on the basis of the position detected by the position sensor. The counter weight carries the receiving means, the inverter, and the motor.

Elevator

A portable-type disk apparatus for a 3.5-inch or less optical disk implemented in a thin, light-weight and miniaturized structure having a vibration-withstanding capability. An optical head assembly is disposed stationarily while an optical disk and a spindle motor for rotating the optical disk are disposed movably in a diametrical direction of the optical disk. The spindle motor is constituted by a brushless motor of a substantially semi-circular form in cross section and having a laterally truncated portion. The optical head assembly including an optical head and a laser circuit is disposed at the side of the laterally truncated portion.

Optical disk apparatus

A motor has a stator and a rotor, the stator having cores and drive coils which generate magnetic fields for rotating the rotor. The stator also has a yoke surrounding the rotor and the rotor is positioned such that it is closer to one part of the outer periphery of the yoke than another part of the outer periphery of the yoke. Such a motor is particularly suitable for use in a disk drive unit as a spindle motor for rotating the disk. Then an actuator for moving a head may be located adjacent the part of the outer periphery of the yoke which is closest to the rotor. This permits the head to approach closely the axis of rotation of the disk without the spindle motor interferring with the movement of the head. The continuous yoke prevents magnetic flux leakage from the spindle motor interferring with the actuator. The actuator may itself have a yoke integral with the yoke of the spindle motor, and/or other components in common.

Disk drive unit having motor components in a compact arrangement

A linear actuator for e.g. a disk drive has a fixed member and a movable member. One of those members carries at least one track of permanent magnets extending in the direction in which the movable member is to move, with adjacent permanent magnets having alternate magnetic polarity. The other member has first and second drive parts, each having at least one pair of opposing sets of teeth. The moveable member or each track passes between those teeth. Each pair of teeth is associated with a corresponding drive coil giving the teeth a magnetic polarity so that there is a magnetic alignment between a polarity of the teeth and the permanent magnets. The drive parts are arranged so that, for any given relative position of the first and second members, the magnetic alignment of the teeth of one drive part is out of phase with the magnetic alignment of the teeth of the other part. In order to ensure that the magnetic alignments are out of phase, there may be a physical displacement between the teeth of the two drive parts. This displacement may be (m.+-.1/2).multidot.T.sub.p, where m is an integer and T.sub.p is the teeth pitch. This gives a phase displacement of 180.degree.. Alternatively, the drive parts may be aligned, and two tracks of permanent magnets be provided with the magnets thereof having opposite polarity for a given track position, or the drive current to the drive coils may be controlled to be out of phase.

Linear actuator

An information recording and erasing method and apparatus of an optical memory medium including a substrate, a guard film, and an intermediate layer portion so disposed between said substrate and said guard film as to include at least a recording material layer having a phase changing with temperature and include at least one good conductor layer, comprising the steps of supplying magnetic flux varying relatively to said good conductor layer to generate eddy currents within said good conductor layer, and heating said recording material layer with heat generated in said good conductor due to the eddy current loss to effect information recording and erasing with respect to said recording material layer.

Optical memory medium and its information recording and erasing method

An electrostatic actuator includes a stationary element and a movable element. The stationary element has a surface which faces a surface of the moving element. Both the surface of the stationary element and the surface of the moving element have electrode lines disposed thereon, including a first set of parallel electrode lines and a second set of parallel electrode lines which are perpendicular to the lines in the first set. By facing the stationary surface and the movable surface towards each other such that the electrode lines of such surfaces are aligned, the movable element can be moved along either of two perpendicular axes when a voltage is applied to the electrode lines.

High-speed two-dimensional electrostatic actuator

An actuator suitable for use in a joint device for driving a robot arm or in a subject follow-up device in a video camera, etc., is designed to have a mobility of a freedom of two degrees or more and is adapted to drive a movable part directly using first piezoelectric motor elements each of which consists of piezoelectric elements having a non-ring-like configuration and an elastic body and second piezoelectric motor elements each of which consists of at most one ring-like piezoelectric element and an elastic member. The actuator exhibits a simplified structure, is small and lightweight, provides a powerful driving power and has a wide range of mobility.

Actuator

The A phase stator and the A phase stator are opposed each other winding same phase coil thereat. The B phase stator and the B phase stator are opposed each other winding same phase coil thereat. The A phase stator and the A phase stator, and the B phase stator and the B phase stator sandwich the mover, respectively. The mover fixes the permanent magnets having small magnetized pitch on the both surfaces thereof. The permanent magnets on both surfaces of the mover comprises the first permanent magnets and the second permanent magnets. The first permanent magnets having one polarity and a predetermined interval each other along the longitudinal direction of the mover are fixed previously on the mover. The second permanent magnets are inserted to the intervals on the mover.

Permanent magnet type linear pulse motor

The present invention provides a large-thrust stepping motor improved in thrust constant by provision of slots at equal intervals between adjacent N and S poles of a permanent magnet disposed on a movable member of the motor or by division of the winding for each phase of a stator of the motor into two or more sections to pass currents independently through the divisional sections in accordance with the speed of the motor. Further, the invention provides a large-thrust stepping motor using a field magnet having large magnetomotive force, the field magnet being formed by combination of a magnet substrate and permanent magnets independent from the magnet substrate.

Structure of stepping motor and method of driving the stepping motor

A laser light flux is divided and synthesized so that its light intensity distribution is changed from a Gaussian distribution to a non-Gaussian distribution. When a laser light flux having a Gaussian distribution is irradiated onto a dividing prism, it is divided into a left part and a right part which are refracted right and left inversely from each other. When the right and left parts are incident on a synthesizing prism, they are refracted again and travel to be overlapped with each other on a recording medium. The light intensity distribution on a segment at the apex of the synthesizing prism is weaker at the central part and stronger at the peripheral part. This is because the light fluxes resulting from the division are inverted in their position so that the central part of the Gaussian distribution is separated left and right while the peripheral part with a weaker light intensity is centered.

Optical recording and reproducing device

In the present invention, a micro Fresnel lens in the shape of a thin film is used. A lens driving member constructed of piezoelectric transducers or of magnets and coils is disposed around the lens. The focus of the lens is adjusted by controlling applied voltages to the piezoelectric transducers or the coils.

Beam spot control device using a thin micro lens with an actuator

A film of a crystal - crystal phase transformation type optical recording alloy is formed on an insulating substrate. Information is erased from the alloy film by heating it with an expedient other than a laser beam. Information is read by sensing reflected light of light projected on the alloy film.

Optical information recording device

The present invention employs as a recording medium a metal or alloy which exhibits an intercrystalline transition before and after writing. In the present invention, two light beams of unequal wavelengths are used so as to write information with the light beam of the longer wavelength and to erase information with the light beam of the shorter wavelength. In changing a written content, a wavelength with which the reflection rate of the recording medium increases is used.

Optical information apparatus and method of recording and erasing

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Hitachi, Japan

Hideki Nihei