Ebara Corporation

Kajima Corporation

Takahide Haga

Katsuhide Watanabe

Yoichi Kanemitsu

Yoshinori Jouno

Mamoru Suzuki

Takayuki Mizuno

Ichiju Satoh

Kenichi Yano

Shinichi Moriyama

Ryuta Katamura

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 for detecting motions of the table and a plurality of active actuators for controlling positions of the table. Processing and controlling means converts values measured by the respective sensors and control forces exerted by the respective active actuators to control and operating amounts for motions in a total of six degrees of freedom: one each for translation in the vertical direction and for rotation about the axis of the translation of the device vulnerable to vibrations, resiliently supported by the vibration isolating apparatus, or the table, and two each for translations on a horizontal plane and rotations about the axes of the translations. The conversion is performed on the assumption that the resilient supporting center matches the center of gravity, and based on the two-dimensional positional relationship between the resilient supporting center and the sensors and the active actuators.

Vibration isolating apparatus for table for mounting device sensitive to vibrations and method therefor

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.

Magnetic levitation control apparatus

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.

Stage positioning device

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.

Vibration cancellation apparatus

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.

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Kanagawa, Japan

Takahide Haga