JPH06288429A - Vibration isolation device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a vibration isolation device capable of always holding a vibration isolation table equipped with a mechanical device that is extremely reluctant to vibrate horizontally in a non-contact state. [Structure] An anti-vibration table 1 on which a mechanical device that dislikes vibration is mounted, a magnetic yoke fixed to the anti-vibration table, and a fixed floor 6 that supports the magnetic yoke by a magnetic force in a noncontact manner. A levitation electromagnet, a displacement sensor 5 for measuring a gap between the levitation electromagnet and the magnetic yoke, a compensation circuit 9 for outputting an exciting current of the levitation electromagnet based on an output from the displacement sensor, and a power An anti-vibration device that includes a controller 7 including an amplifier 10 and supports the anti-vibration table in a floating manner in a non-contact manner. An inclination sensor installed on the anti-vibration table for detecting an inclination angle of the anti-vibration table 1 from the horizontal. 20 is provided, and the vibration isolation table is held horizontally by adding or subtracting the output from the tilt sensor 20 to the output of the displacement sensor 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration device, and more particularly to an anti-vibration device for removing vibrations from a floor by suspending an anti-vibration table equipped with a mechanical device which is not sensitive to vibrations by magnetic force.

[0002]

2. Description of the Related Art Conventionally, mechanical devices such as an electron microscope and a semiconductor manufacturing device, which are extremely reluctant to vibrate, have been installed in a vibration isolator and installed in a factory or the like. As a conventional vibration isolation device,
An anti-vibration device using magnetic levitation that can realize high-performance anti-vibration has been developed in place of the air spring and rubber that have been used for a long time, and the details thereof are disclosed in, for example, Japanese Patent Laid-Open No. 2-203040.

FIG. 2 shows an example of such a magnetic levitation vibration isolator. On the vibration isolation table 1, mechanical devices such as an electron microscope and a semiconductor manufacturing device that are extremely reluctant to vibrate are mounted (not shown). Instead, it is held in a non-contact floating state by the electromagnetic actuator 2. Therefore, even if the installation floor on which the electromagnetic actuator 2 is installed vibrates due to an earthquake or the like, the vibration is not transmitted to the vibration isolation table 1 that is floated and held in a non-contact manner, and the mechanical device or the like that is extremely reluctant to install the vibration is installed. Not affected by floor vibration.

FIG. 3 is an explanatory view of an electromagnetic actuator of the vibration isolator. A magnetic yoke 3 is fixed to a vibration isolation table 1 which is equipped with a device for vibration isolation. Installation floor 6
The levitation electromagnet 4 fixed to the above supports the magnetic yoke 3 to which the vibration isolation table 1 is fixed by the magnetic attraction force in a non-contact manner. The gap c between the magnetic pole of the levitation electromagnet 4 and the target magnetic yoke 3 is measured by the displacement sensor 5. The controller 7 includes a compensation circuit 9 and a power amplifier 10.
Based on the output from the displacement sensor 5, the magnetic yoke 3
The exciting current of the levitation electromagnet 4 is controlled so that the vibration isolation table 1 with fixed is stably supported at the target position by levitation.

Further, a horizontal control electromagnet 14 is provided for supporting the vibration isolation table in a non-contact manner and for performing horizontal vibration isolation control. The horizontal acceleration sensor 15 measures the horizontal acceleration, and controls the exciting current of the horizontal control electromagnet 14 so that the compensation circuit 19 and the power amplifier 22 stably support the vibration isolation table 1 in the horizontal direction. .

[0006]

In the conventional vibration isolator, since the lateral rigidity in the horizontal direction can be reduced, the vibration transmission in that direction can be reduced. However, because of its low lateral rigidity, when the levitation table tilts with respect to the horizontal direction due to the level of the installation floor, variations in the target value of the levitation control displacement sensor, etc. There arises a problem that the magnetic yokes that move horizontally and are fixed to the vibration isolation table come into contact with the levitation electromagnet on the installation floor.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an anti-vibration device capable of holding the anti-vibration table horizontally while always floating in a non-contact manner.

[0008]

[Means for Solving the Problems] An anti-vibration table equipped with a mechanical device that dislikes vibration, a magnetic yoke fixed to the anti-vibration table, and the magnetic yoke is levitationally supported by a magnetic force in a non-contact manner. A levitation electromagnet fixed to the installation floor, a displacement sensor that measures the gap between the levitation electromagnet and the magnetic yoke, and a compensation circuit that controls the exciting current of the levitation electromagnet based on the output from the displacement sensor. In a vibration isolation device including a controller including a power amplifier, the vibration isolation table includes an inclination sensor that detects an inclination angle of the vibration isolation table from the horizontal, and an output from the inclination sensor is output by the displacement sensor. The vibration isolation table is controlled to be held horizontally by adding or subtracting to the output.

[0009]

In the present invention, when the anti-vibration table is tilted due to variations in the level of the installation floor, the tilt sensor detects the tilted state of the vibration isolation table, and the tilt sensor outputs a detection signal to the controller. Is output. In the controller, based on the displacement signal of the gap between the levitation electromagnet and the magnetic yoke by the displacement sensor, and the detection signal from the tilt sensor, a current compensating circuit for exciting the exciting coil of the levitation electromagnet, The gap is controlled by controlling with a power amplifier. As a result, the tilted state of the vibration isolation table is corrected and the vibration isolation table is horizontally held in a non-contact state.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the vibration isolator according to the present invention will be described below with reference to FIG.

FIG. 1 shows a structure in which an inclination sensor is attached to the vibration isolator shown in FIGS. 2 and 3. The same components are designated by the same reference numerals and their description is omitted. .

In the vibration isolator of this embodiment, as shown in the figure, an inclination sensor 2 for detecting the inclination state of the vibration isolation table 1 is used.
0 is attached to the vibration isolation table 1. This tilt sensor 2
0 can detect the inclination angle and the inclination direction when the vibration isolation table 1 is changed from the horizontal state to the inclined state.

An acceleration sensor, for example, is used as the inclination sensor. The acceleration sensor is usually provided with a pendulum-like element and electrically outputs the acceleration applied to the pendulum. At the same time, the vertical position of the pendulum can be extracted as a DC electric signal, and the signal corresponding to the tilt angle with respect to the horizontal plane can be easily detected.

The output of the tilt sensor 20 is amplified by the tilt sensor amplifier 20a and applied to the control system of the actuator 2 that holds the vibration isolation table 1 in a floating state. That is, the output of the inclination sensor 20 is added or subtracted by the adder 21 to the output of the displacement sensor 5 that detects the gap c between the magnetic yoke 3 and the levitation electromagnet 4. Here, in order to control the vibration isolation table 1 horizontally, one actuator (left side in the figure) of the vibration isolation table 1 subtracts the tilt sensor output in the adder 21, and the other actuator (right side in the figure) tilts. The sensor outputs are added. The mechanism in which the output of the adder 21 controls the exciting current of the levitation electromagnet 4 by the compensating circuit 9 and the power amplifier 10 is the same as the conventional actuator shown in FIG.

The intervals between the actuators shown in the figure, which are detected by the displacement sensor, are indicated by the symbols C ₁ and C ₂ . The target value of the gap C in the four electromagnetic actuators 2 constituting one anti-vibration device is initially set to be the same in all the four electromagnetic actuators 2, and therefore the intervals C ₁ , C _{2 in the} two electromagnetic actuators 2 shown in the figure are set. Are equal. However, when the anti-vibration table 1 is tilted due to the various reasons described above, if the interval C ₂ between the electromagnetic actuators 2 in the lower position is increased and the interval C ₁ between the electromagnetic actuators 2 in the higher position is decreased, the anti-vibration is performed. Since the table 2 is held in the horizontal state, it is necessary to control the intervals between them so that C ₂ > C ₁ .

Therefore, the tilt state of the vibration isolation table 1 is measured by the tilt sensor 20, and its signal is sent to the controller 7.
Of the tilt sensor amplifier 20a. The signal amplified by the gradient amplifier 20a is sent to each adder 21 for each electromagnetic actuator 2. A signal sent from the displacement sensor 5 corresponding to a high place through the sensor amplifier 5a is subjected to subtraction processing by the adder 21, while
From the displacement sensor 5 corresponding to a low place to the sensor amplifier 5a
The adder 21 performs addition processing on the signal sent via the. Then, based on the output from each adder 21,
A control signal is generated by each levitation compensating circuit 9, and the power amplifier 10 that has received each control signal amplifies the power and drives the levitation electromagnet 4. The magnetic attraction force of the levitation electromagnet 4 of the electromagnetic actuator 1 in the low position is increased, and the magnetic attraction force of the levitation electromagnet 4 of the electromagnetic actuator in the high position is decreased. As a result, the tilted vibration isolation table 1
The low part of rises and the high part falls. Therefore, by such a control system, the anti-vibration table 1 is levitated and held horizontally in the non-contact state in the equilibrium state.

[0017]

Since the present invention is configured as described above, even if the vibration isolation table is tilted, the tilt sensor detects it and outputs the required exciting current to the levitation electromagnet to cause vibration isolation. The table can be held horizontally without contact. Therefore, the problem that the vibration isolation table moves even when the lateral rigidity is low and the magnetic body yoke contacts the levitation electromagnet is solved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a vibration isolation device according to the present invention.

FIG. 2 is a perspective view of an embodiment of a vibration isolation device according to the present invention.

FIG. 3 is an explanatory diagram of an actuator of a vibration isolation device.

[Explanation of symbols]

 1 Vibration Isolation Table 2 Actuator 3 Magnetic Yoke 4 Floating Electromagnet 5 Displacement Sensor 6 Installation Floor 7 Controller 9 Compensation Circuit 10 Power Amplifier 20 Inclination Sensor 21 Adder

Claims (2)

[Claims] 1. An anti-vibration table equipped with a mechanical device that dislikes vibration, a magnetic yoke fixed to the anti-vibration table, and a magnetic floor fixed to an installation floor that supports the magnetic yoke in a non-contact manner by magnetic force. From the levitation electromagnet, a displacement sensor that measures the gap between the levitation electromagnet and the magnetic yoke, a compensation circuit that controls the exciting current of the levitation electromagnet based on the output from the displacement sensor, and a power amplifier In a vibration isolation device including a controller, the vibration isolation table includes an inclination sensor that detects an inclination angle of the vibration isolation table from the horizontal, and the output from the inclination sensor is added to the output of the displacement sensor. Alternatively, the vibration isolation table holds the vibration isolation table horizontally by subtracting. 2. The vibration isolator according to claim 1, wherein an acceleration sensor that measures an absolute acceleration in a horizontal direction is used as the inclination sensor.