Abstract: For stably supporting a vibration isolating table to isolate a vibration-protected apparatus from external vibrations, a vibration isolating apparatus comprises a vibration isolating table 10; magnetic levitation devices 31-34 for supporting the vibration isolating table 10 without contact and applying a control force thereto; displacement sensors 41-44 for detecting amounts of relative displacement of the vibration isolating table 10 with respect to a foundation to output displacement signals; and acceleration sensors 61-63 for outputting acceleration signals upon detection of vibrations of the foundation.

Abstract: There are disclosed a vibration isolating apparatus and a vibration eliminating method imposed less restrictions on the positioning of components, such as active actuators, forming part of the vibration isolating apparatus. The vibration isolating apparatus can be implemented with a relatively simple controller (such as an analog circuit) and can limit the interference of control forces to a practically ignorable degree. The vibration isolating apparatus has a table for mounting thereon a device vulnerable to vibrations, a plurality of sensors 15-20 for detecting motions of the table and a plurality of active actuators 11-14 for controlling positions of the table.

Abstract: A magnetic levitation control apparatus comprises a pair of electromagnets for holding a levitated body having a magnetic body in the levitated state. A signal source for supplying a voltage signal of a frequency on a level such that enables the electromagnets to function as the position sensor, wherein a control voltage signal for controlling the magnetic attraction of the electromagnets is superimposed on the voltage signal. A circuit differentially supplies the voltage signal to the pair of electromagnets to form a position signal of the levitated body from an add signal of currents respectively from the electromagnets, and a circuit detects a control current of the electromagnets from a subtraction signal of currents respectively from the electromagnets. A controller generates a control voltage signal of the electromagnets from the detected position signal of the levitated body and, in addition, corrects the position signal detected from the detected control current of the electromagnets.

Abstract: A micro-positioning apparatus enables stable and rapid positioning of a stage on which a specimen is placed. The apparatus has a stage for placing a specimen to be radiated with a beam, actuators for levitating the stage and controlling a movement of the stage, a first position sensor for measuring a relative displacement between the stage and the actuators, a second position sensor for measuring a relative displacement between an actual radiation position of the beam on the specimen and a target radiation position, and a controller for positioning the stage so as to decrease the relative displacement detected by the second sensor.

Abstract: There are disclosed a vibration isolating apparatus and a vibration eliminating method imposed less restrictions on the positioning of components, such as active actuators, forming part of the vibration isolating apparatus. The vibration isolating apparatus can be implemented with a relatively simple controller (such as an analog circuit) and can limit the interference of control forces to a practically ignorable degree. The vibration isolating apparatus has a table for mounting thereon a device vulnerable to vibrations, a plurality of sensors 15-20 for detecting motions of the table and a plurality of active actuators 11-14 for controlling positions of the table.

Abstract: The polishing apparatus can control the attitude of the top ring with respect to a surface of a turntable of a polishing apparatus is controlled so as to provide a uniform polish surface pressure across the entire polish surface. The polishing apparatus includes the turntable having an abrading surface, a top ring for holding an object to be polished to keep the object surface in moving contact with the abrading surface while rotating the turntable and the top ring, a magnetic bearing assembly for supporting a rotation shaft of the top ring by means of a thrust bearing device and at least one radial bearing device, and an attitude controller for controlling an orientation of the top ring with respect to the turntable through the magnetic bearing assembly.

Abstract: A polisher provided with a vibration detection system which can detect vibration caused by rubbing between an article to be polished and a polishing member without any noise which is generated in prior art polishers. The polisher includes a turntable assembly with a polishing surface, a rotatable carrier assembly for holding an article to be polished in such a manner that the article is kept in contact, under pressure with the polishing member while being polished. A vibration detector is provided on the rotatable carrier assembly in order to detect the vibration caused by the rubbing between the article and the polishing member of the turntable assembly. A light signal emission device is provided on the rotatable carrier assembly and is adapted to receive electrical signals transmitted from the vibration detector to generate and emit light signals in response to the vibration detected by the detector. A light signal receiving device is provided on a stationary part of the polisher.

Abstract: The polishing apparatus can control the attitude of the top ring with respect to a surface of a turntable of a polishing apparatus is controlled so as to provide a uniform polish surface pressure across the entire polish surface. The polishing apparatus includes the turntable having an abrading surface, a top ring for holding an object to be polished to keep the object surface in moving contact with the abrading surface while rotating the turntable and the top ring, a magnetic bearing assembly for supporting a rotation shaft of the top ring by means of a thrust bearing device and at least one radial bearing device, and an attitude controller for controlling an orientation of the top ring with respect to the turntable through the magnetic bearing assembly.

Abstract: A polishing apparatus is used for polishing a workpiece such as a semiconductor wafer to a flat mirror finish. The polishing apparatus has an interlock function includes a turntable having a polishing surface thereon, a top ring for holding a workpiece to be polished and pressing the workpiece against the polishing surface on the turntable, a first motor for rotating the turntable, and a second motor for rotating the top ring. The polishing apparatus further comprises a first actuator for lifting and lowering the top ring, a second actuator for moving the top ring in a horizontal direction, and a control unit for controlling the motors and the actuators. The control unit controls the motors and the actuators in such a manner that when an abnormality is detected in at least one of the motors and the actuators, at least one of the motors and the actuators other than that of the abnormality performs a predetermined operation.

Abstract: A compact vibration cancellation apparatus based on a combination of air springs and electromagnetic actuators with smaller power capacity enables an anti-vibration table to be maintained in a level position even when the center of gravity of the anti-vibration table moves a large distance because of a movement of objective equipment on the table. The vibration cancellation apparatus is operable for isolating floor vibration or for canceling vibration of the objective equipment on the anti-vibration table. The apparatus includes displacement sensors, acceleration sensors, a levitation position control device, a vibration canceling control device, and air spring actuators for supporting four corners of the anti-vibration table by air pressure. The air pressure in each air spring actuator is controlled in response to a change of load which corresponds to a movement of the center of gravity caused by movement of the objective equipment on the anti-vibration table.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A displacement sensor system is provided which is capable of simultaneously and independently detecting displacements in two directions orthogonal to an axis of an object to be detected, using a less number of displacement sensors than before. The displacement sensor system, for enabling the simultaneous detection of displacements in two directions orthogonal to an axial direction of a pillar-shaped member, has a plurality of displacement sensors positioned around the pillar-shaped member, and a detector circuit for receiving outputs of the plurality of displacement sensors to output signals indicative of displacements in the two directions orthogonal to the axial direction of the pillar-shaped member. The detector circuit includes a multi-bridge circuit for parallelly connecting a circuit having the plurality of displacement sensors connected in series to a plurality of resistor circuits.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A vibration eliminating apparatus for eliminating vibration suspends a floor board from an installation floor. A supporting electromagnet is provided on the installation floor in order to suspend a magnetic member fixed to the floor board by a magnetic force. The magnetic member is provided with a thin magnetic pole through a non-magnetic member, and a control electromagnet having a yoke located in proximity to the thin magnetic pole is provided to control a horizontal position of the floor board. A vibration detector is provided to detect vibration of the floor board, and a vibration monitor is used to decide whether or not vibration detected by the vibration detector is within an allowable range of a machine mounted on the floor board and output an operation enable signal only when vibration is within the allowable range.

Abstract: A system for supporting a rotor without contact with a stator comprising a magnetic bearing apparatus mounted on the stator and including a controlling magnet means fixed to the stator, a non-controlling magnetic pole fixed to the stator, a biasing magnetic poles sandwiched between the controlling magnet and the non-controlling magnetic pole, and a rotor magnetic pole fixed to the rotor to enable the magnetic path of a biasing flux to run in a plane which includes the longitudinal axis of the stator. The non-controlling and rotor magnetic poles may have teeth facing each other.