Ebara Corporation

Kajima Corporation

Ebara Research Co., Ltd.

National Aerospace Laboratory, Ebara Research Co., Ltd.

Yoichi Kanemitsu

Katsuhide Watanabe

Yuji Shirao

Hiroyuki Shinozaki

Mamoru Suzuki

Masao Matsumura

Shunichi Aiyoshizawa

Kenichi Yano

Takahide Haga

Shinichi Moriyama

Naoji Hiraki

Norio Kimura

Yukio Ikeda

Atsushi Nakajima

Satoshi Mori

Takayuki Mizuno

Naoaki Ogure

Masayoshi Hirose

Katsuyuki Aoki

Noburu Shimizu

Tadashi Kataoka

Yoshio Sato

Minoru Takizawa

Katsuaki Usui

Kazuyuki Kasahara

Fumio Kondo

Chikara Murakami

Daisuke Konno

Takeshi Yoshioka

Masaaki Kajiyama

Takashi Kataoka

Manabu Toshimitsu

Seigo Katsuta

Masaru Nakaniwa

Masato Eguchi

Hideki Kondo

Yoshiyuki Maruta

Hideo Tsuboi

Shunsuke Mimura

Tatsuo Hinata

Ryuta Katamura

An electron microscope has an electron gun for emitting an electron beam, a specimen holder for holding a specimen thereon, and a deflection coil for applying the electron beam from the electron gun to the specimen on the specimen holder. A controller produces a differential signal representing the difference between a signal from a vibration sensor which detects vibrations of the electron gun and a signal from another vibration sensor which detects vibrations of the specimen holder. The differential signal is added to a deflection signal for the deflection coil for thereby effecting feedforward control of the electron beam to cause the electron beam to reach the specimen on the specimen holder, irrespective of the vibrations of the electron gun and the specimen holder.

Electron microscope

A magnetically levitated vibration damping apparatus includes a table having a flat board of a magnetic material, an electromagnetic actuator for applying magnetic attractive forces to the flat board to levitate the table, a displacement sensor for detecting relative displacement between the flat board and the electromagnetic actuator, an acceleration sensor for detecting absolute acceleration of the table, and a control system for controlling a current supplied to the electromagnetic actuator based on signals from the displacement sensor and the acceleration sensor according to a first control rule for controlling a gap between the flat board and the electromagnetic actuator based on the signal from the acceleration sensor and a second control rule for controlling vibrations of the table based on the signal from the acceleration sensor, the second control rule including stability control of relative displacement of the table.

Magnetically levitated vibration damping apparatus

A vibration damping apparatus has a vibration-isolating table for placing an object thereon which is to be isolated from vibrations, an air spring mounted on an installation floor and supporting the vibration-isolating table for attenuating vibrations from the installation floor, an air pressure controller for controlling an air pressure of the air spring, a displacement sensor for detecting a relative displacement between the vibration-isolating table and the installation floor and supplying a signal indicative of the detected relative displacement to the air pressure controller, and a spring element acting between the vibration-isolating table and the installation floor for positioning the vibration-isolating table horizontally. An electromagnet is disposed between the vibration-isolating table and the installation floor for actively attenuating vibrations of the vibration-isolating table. The vibration damping apparatus is operated to position the vibration-isolating table horizontally by means of the spring elements, and vertically by means of the air spring.

Vibration damping apparatus

A control system for controlling a linear actuator including magnetic bearings for levitating a robot arm and a pulse motor for linearly driving the arm in a non-contact manner is disclosed, which comprises a displacement detection unit including displacement sensors, first and second calculation units, moving amount detection unit and adding circuit. The displacement detection unit detects displacement values of the arm from a reference posture, the first calculation unit calculates guiding (y), levitation (z), roll (p), pitching (q), and yaw (r) control current values in response to the displacement values and provides guiding, levitation, roll, pitching, and yaw control current signals (, , , , ). The moving amount detecting circuit detects a moving amount (X.sub.0) of the arm from a reference position in response to an operation of the pulse motor, and provides a compensation current value (.DELTA.Iq') proportional to the moving amount, and the adding circuit adds the compensation current value (.DELTA.Iq') to the pitching control current signal (). The second calculation unit, in response to the guiding, levitation, roll and yaw control current signals (, , , ) and the added pitching control current signal (+.DELTA.Iq'), calculates drive current control values to compensate drive current flowing through the magnetic bearings.

Control system for a linear actuator including magnetic bearings for

Magnetic levitation conveyor apparatus

A thin-film forming device including a reaction chamber having an atmosphere different from that in the outside world, a susceptor rotatably disposed in the reaction chamber for mounting a substrate thereon to form a thin film thereon, and a nozzle disposed within the reaction chamber facing the susceptor for supplying a thin-film forming material on the substrate, the thin-film forming device comprises: a levitating means including magnetic bearings for non-contact support of the susceptor; and a driving means for rotating the susceptor at high speed, to thereby increase the rotational speed of the susceptor and the thin-film forming rate.

Thin-film forming apparatus with magnetic bearings and a non-contact

An electromagnetically suspended floating floor apparatus in which a floating floor on which machines are set up is suspended from an installation floor with electromagnetic actuators so that the floating floor is spatially separated from the installation floor whereby no vibration is transmitted to equipment on the floating floor. The floating floor apparatus comprises the floating floor suspended from the installation floor at a plurality of supporting points by electromagnetic actuators, a light emitting member, fixed to a beam or a pillar, which emits a horizontal light beam, and a photosensor fixed to the installation floor which outputs a position signal representing a position of incidence of the horizontal light beam to the electromagnetic actuators. On the basis of the position signal, the electromagnetic actuators control a vertical position of the floating floor.

Electromagnetically suspended floating floor apparatus

There is provided a vibration eliminating apparatus utilizing a magnetic suspending system which achieves zero power control. The vibration eliminating apparatus includes a table on which equipment to be installed, magnetic yokes fixed on the table, control magnets for suspending the magnetic yokes from an installation floor, displacement sensors for measuring gaps between the control magnets and the magnetic yokes, power amplifiers for supplying exciting currents to the control magnets, and compensation circuits for controlling the exciting currents of the control magnets by supplying outputs from the displacement sensors to the power amplifiers. Each control magnet includes a permanent magnet for generating a bias magnetic flux and an electromagnet for generating a control magnetic flux to form a magnetic circuit. An integrated value of the exciting current fed to the electromagnet is fed back to the power amplifier.

Zero-power control type vibration eliminating apparatus

A robot with no mechanically contacting components are suitable for use in special environments such as semiconductor manufacturing processes where dust and lubrication are matters of important concern. The robot has a linear actuator composed of magnetic bearings and a linear motor for moving a robot arm linearly without mechanical contact, and a rotary actuator composed of magnetic bearings and a rotary motor for rotating a body which supports the linear actuator, around the rotary actuator without mechanical contact.

Robot with dust-free and maintenance-free actuators

A dynamic pressure bearing is provided with a moving side bearing member and a fixed side bearing member so as to support a rotor for rotation by generating a fluid dynamic pressure between the moving side bearing member and the fixed side bearing member. The dynamic pressure bearing includes a high-frequency exciting device for applying a high-frequency vibration to the fixed side bearing member at the time of at least one of start-up and shutdown of the rotor. In this way, both bearing members are kept almost free from contact with each other and a frictional resistance at start-up and/or shutdown is minimized.

Dynamic pressure bearing

A spindle motor has a rotor supported by a stator through a thrust bearing and a radial bearing. At least the thrust bearing is a hydrodynamic bearing. The spindle motor is provided with a device for adjusting the thrust laod that is applied to the thrust bearing. The load adjusting device has an electromagnet that is provided on the stator and a permanent magnet that is provided on the rotor in opposing relation to the electromagnet. Either the repelling force or the attraction force, which acts between the electromagnet and the permanent magnet, is controlled by changing the current supplied to the electromagnet.

Spindle motor

An inductance-type displacement sensor which can measure the displacement of a measured object of magnetic material without any contact with the object. A pair of series connected coils is provided adjacent to the object so that the inductance of the coils varies in response to a displacement of the object from a predetermined position. The inductance, the number of windings, the direction of the windings and the section of each of the cores are so set that the magnetic flux produced by one of the coils runs in a direction opposite to that of the magnetic flux produced by the other coil and the densities of the respective magnetic fluxes are identical with each other.

Inductance-type displacement sensor for eliminating inaccuracies due to

A turbo molecular pump includes a magnetic bearing system which includes a rotor having an impeller connected to a shaft and a motor. A stator is positioned between the shaft and the impeller. Radial magnetic bearings, an active axial magnetic bearing and emergency bearings are each provided between the rotor and the stator. The radial magnetic bearings include passive magnetic bearings provided on the rotor and the stator respectively. The axial magnet bearing is disposed in the vicinity where the impeller is connected to the shaft. The emergency bearings are disposed on a low vacuum side with one emergency bearing being positioned near the axial magnetic bearing. A diameter of the shaft is made smaller than an inside diameter of the emergency bearing near the axial magnetic bearing. By this arrangement, only one control axis is necessary for controlling the position of the rotor. Disassembling of the shaft and impeller is easy and contamination of the high vacuum side can be prevented.

Turbo molecular pump

An apparatus for correcting imbalance of a rotor suspended by a magnetic bearing system including a displacement sensor for detecting a displacement of the rotor. An imbalance correcting circuit applies a trial imbalance correcting signal to the magnetic bearing system. A command computer applies an amount of correction to the imbalance correcting circuit and calculates an influence factor of the imbalance correcting signal on the basis of outputs from the displacement sensor before and after the imbalance correcting signal is applied to the magnetic bearing system, so as to cause the imbalance correcting circuit to apply a predetermined imbalance correcting signal produced from the influence factor to the magnetic bearing system, thereby minimizing the output of the displacement sensor to correct mass-imbalance of the rotor.

Imbalance correcting apparatus for a rotor

A cemtrifugal pump in which the thrust generated by an impeller is balanced by the operation of a balancing disc device. In the pump, a magnetic bearing is employed as an axial thrust bearing. The distance between the surface of a balancing disc and an axial displacement detecting surface which, together with the pump shaft, and the distance between such surface of a balancing disc seat is a fixed-side member which faces the balancing disc surface. The surface of a displacement sensor is another fixed-side member which faces the axial displacement detecting surface and are made equal to each other, or the latter distance is made slightly larger than the former distance. The neutral position of the magnetic thrust bearing is made to substantially coincide with the axial position of the rotator of the pump and is determined by the balancing disc device during running of the pump. By these arrangements, the position of the stator is determined by the balancing disc device during normal operation of the pump, whereas the position is determined by the magnetic thrust bearing when the pump is at rest or in a transient running state.

Centrifugal pump having magnet bearing

Growing community of inventors

Kanagawa, Japan

Yoichi Kanemitsu