JPH03213745A - Precision vibration isolating table - Google Patents

Abstract

PURPOSE:To restore the inclination and vertical level fluctuation of surface tables rapidly with high accuracy by providing the second surface table placed on the first surface table, non-contact displacement sensors for detecting the position of the second surface table, actuators for controlling the displacement of the second surface table, and control parts for the actuators. CONSTITUTION:This precision vibration isolating table is provided with a second surface table 4A, provided on a first surface table 4, for placing an vibration isolating object; non-contact displacement sensors 1 for detecting the position of the second surface table 4A; actuators 2, installed between the first surface table 4 and second surface table 4A, for controlling the displacement of the second surface table 4A on the basis of position signals detected by the non- contact displacement sensors 1; and control parts 3 for driving/controlling the actuators 2. There are further provided with automatic pressure regulators 6 comprising sensing lever 61 fitted in contact with the lower face of the first surface table 4, air springs 5, and an additional tank 51. In this precision vibration isolating table, the large vibration of the first surface table 4 is controlled as in the existing way, as well as the inclination and level fluctuation of the second surface table 4A can be restored rapidly with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a precision vibration isolation table, and more particularly to a precision vibration isolation table that allows for easy tilting of the surface plate and fine adjustment in the vertical direction.

[Prior Art] Precision instruments such as semiconductor manufacturing equipment, inspection equipment, electron microscopes, various analytical instruments, and optical measuring instruments are used by being mounted on vibration isolation tables. As shown in FIG. 6, the vibration isolation table installed on the floor 90 includes a surface plate 40 on which precision equipment is mounted, and an automatic pressure sensing lever 61 attached in contact with the lower surface of the surface plate 40. A regulator 60, an air spring 50 that is controlled by a valve (not shown) of the automatic pressure regulator 60 and is provided in contact with the lower surface of the surface plate 40, and an additional tank 51 that supplies air to the air spring 50. and a frame 80. An automatic pressure regulating valve has already been proposed by the applicant (Utility Model Application No. 148715/1983).
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When the vibration of the surface plate 40 is transmitted to the sensing lever 61, the valve of the automatic pressure regulator 60 opens and closes in response to the vertical movement of the sensing lever 61, and air is supplied to the air spring 50 from the additional tank 51. Alternatively, air is released from the air spring 50 to restore the vertically moved surface plate 40.

[Problems to be Solved by the Invention] However, since the automatic pressure regulator 60 used in the conventional vibration isolation table has a slow response, it is not possible to expect high-speed restoration that returns to almost the original position in a short time, and it is difficult to prevent hunting. Therefore, the dead zone was large and the reconstruction accuracy was poor (Figure 5). For this reason, as the precision equipment mounted on these devices has become more sophisticated and precise, there has been a demand for improvements in the functionality of the vibration isolation table itself.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and is capable of quickly and accurately restoring the inclination and vertical level fluctuations of a surface plate on which equipment is mounted. The purpose is to provide a precision vibration isolation table.

[Means for Solving the Problems] In order to achieve the above object, a precision vibration isolation table according to the present invention includes an air spring, a first surface plate supported by the air spring,
a second surface plate, which has an automatic pressure regulator that drives an air spring according to the displacement of the first surface plate, is provided on the first surface plate, and on which an object to be vibration-isolated is placed; a non-contact displacement sensor that detects the position of the surface plate; and a non-contact displacement sensor that is installed between the first surface plate and the second surface plate and detects the displacement of the second surface plate based on the position signal detected by the non-contact displacement sensor. It has a structure that includes an actuator to control and a control section to drive and control the actuator.

[Example] Hereinafter, preferred embodiments of the precision vibration isolation table according to the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the precision vibration isolation table according to the present invention has a first
A second surface plate 4A provided on the surface plate 4 on which a vibration-isolating object is placed, a non-contact displacement sensor 1 that detects the position of the second surface plate 4A, and a first surface plate 4. The actuator 2 is installed between the second surface plates 4A and controls the displacement of the second surface plate 4A based on the position signal detected by the non-contact displacement sensor 1, and the control section 3 is configured to drive and control the actuator 2. , and an automatic pressure regulator 6 having a sensing lever 61 attached in contact with the lower surface of the first surface plate 4, and a valve (not shown) of the automatic pressure regulator 6 controlling the first surface plate. 4, an additional tank 51 that supplies air to the air spring 5, and a frame 8. The lower part of the additional tank 51 is installed on the floor 9. There is.

A non-contact displacement sensor 1 that detects the position of the second surface plate 4A is attached to a bracket 7 provided on the frame 8. The second surface plate 4A on which the object to be vibration-isolated is placed is the first
It is supported by an actuator 2 provided on a surface plate 4. The control unit 3 is placed on the first surface plate 4, or
It will be set up in a separate location.

As shown in FIG. 2, the basic configuration of the control mechanism portion consisting of a non-contact displacement sensor 1, an actuator 2, and a control unit 3, which is a feature of the present invention, is, for example, four non-contact displacement sensors 1 and one actuator 2. There are four or more control sections 3 (not shown in FIG. 2), but there is no particular restriction on the number of them.

The position signal of the second surface plate 4A detected by the non-contact displacement sensor 1 is transmitted to the control section 3, and the control section 3 drives and controls the actuator 2. The actuator 2, which is driven in the direction opposite to the displacement of the second surface plate 4A, quickly restores the second surface plate 4A to a constant state (FIG. 3).

In the precision vibration isolation table according to the present invention, large vibrations of the first surface plate 4 are controlled in the same manner as in the conventional case.

That is, when the vibration of the first surface plate 4 is transmitted to the sensing lever 61, the valve of the automatic pressure regulator 6 opens and closes in accordance with the vertical movement of the sensing lever 61, and air is supplied to the air spring 5 from the additional tank 51. Air is supplied or released from the air spring 5 to restore the vertically moved first surface plate 4. On the other hand, restoring the vibration of the second surface plate 4A due to minute displacements that have a large effect on the mounted precision equipment and the vibration of the first surface plate 4 is carried out by the control unit 3 based on the position signal detected by the non-contact displacement sensor 1. Actuator 2 controlled by
is actively applied to the second surface plate 4A.

The non-contact displacement sensor 1 detects the relative displacement between the floor 9 and the second surface plate 4A without contacting the second surface plate 4A, and is an optical (LED) displacement sensor or an air variation type. Known displacement sensors such as displacement sensors, laser displacement sensors, ultrasonic displacement sensors, and eddy current displacement sensors are preferably used. The installation position is not limited to the top of the bracket 7, and may be any position where the relative displacement between the second surface plate 4A and the floor 9 can be detected.

The actuator 2 is preferably a known actuator that can be driven at high speed, such as a linear motor, a piezoelectric actuator, an electric cylinder, a hydraulic cylinder, an ultrasonic motor, an actuator using an amorphous magnetic element, or an actuator using a magnetostrictive element.

Looking at the recovery characteristics of the precision vibration isolation table according to the present invention, as shown in FIG. 4, it returns to the initial state in a very short time, and the recovery characteristics of the conventional vibration isolation table shown in FIG. Superior performance was confirmed compared to .

Note that the control mechanism part that is a feature of the present invention, that is, the four non-contact displacement sensors, the four actuators 2, and the control unit 3, is different from the vibration control mechanism of the conventional vibration isolation table used. Needless to say, by adding them in series, the same effect as the precision vibration isolation table according to the present invention can be obtained.

[Effects of the Invention] As is clear from the above embodiments, the precision vibration isolation table according to the present invention has an air spring, a first surface plate supported by the air spring, and a displacement of the first surface plate. Since it has an automatic pressure regulator that drives the air spring accordingly, large vibrations can be controlled. A non-contact displacement sensor detects the position of the surface plate, and the displacement of the second surface plate is controlled based on a position signal detected by the non-contact displacement sensor installed between the first surface plate and the second surface plate. Since it is equipped with an actuator and a control unit that drives and controls the actuator, it can quickly and easily correct tilts and minute level fluctuations of the surface plate on which precision equipment is mounted.
It can be restored to a high degree of accuracy, and is compatible with the high performance and precision of precision equipment installed.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the configuration of the precision vibration isolation table according to the present invention, Figure 3 is a diagram explaining its control method, and Figure 4 is a diagram showing the restoring characteristics of the precision vibration isolation table according to the present invention. , FIG. 5 is a diagram showing the restoration characteristics of the conventional vibration isolation table, and FIG. 6 is a diagram showing the configuration of the conventional vibration isolation table. 011000. , non-contact displacement sensor 3311.10. Actuator 0901111. Control unit 001190. First surface plate A, second surface plate 989381. Air spring 001191. automatic pressure regulator

Claims (1)

[Claims] an air spring, a first surface plate supported by the air spring, and an automatic pressure regulator that drives the air spring according to displacement of the first surface plate; a second surface plate provided above on which a vibration-isolating object is placed; a non-contact displacement sensor that detects the position of the second surface plate; Precision vibration isolation characterized by comprising an actuator that is installed between and controls the displacement of the second surface plate based on a position signal detected by the non-contact displacement sensor, and a control section that drives and controls the actuator. The stand.