JPH03213744A - Precision vibration isolating table - Google Patents

Abstract

PURPOSE:To restore the inclination of a surface table mounted with equipment rapidly with high accuracy by providing non-contact displacement sensors for detecting the displacement of the surface table, actuators for controlling the displacement of the surface table, and control parts for the actuators. CONSTITUTION:This precision vibration isolating table is provided with three non-contact displacement sensors 1 mutually spaced facing the lower face of a surface table 4 to detect its displacement, actuators 2 for controlling the displacement of the surface table 4 on the basis of the difference signals of the displacement quantity detected by three 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 levers 61 fitted in contact with the lower face of the surface table 4, air springs 5, and an additional tank 51 for supplying air. Large vibration can be controlled as in the existing way, as well as the surface table 4 can be restored rapidly with high accuracy even against such displacement as minute inclination of the surface table 4 mounted with precision mechanical equipment and therefore well corresponds to the high performance and high accuracy of the mounted precision mechanical equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a precision vibration isolation table, and more particularly to a precision vibration isolation table that controls the rotation mode of a surface plate and eliminates inclination.

[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 vertical movement of the surface plate 40 is transmitted to the sensing lever 61, the valve of the automatic pressure regulator 60 opens and closes in accordance with 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 was made to solve the above-mentioned problems, and provides a precision vibration isolation table that can quickly and accurately restore the inclination of a surface plate on which equipment is mounted. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, a precision vibration isolation table according to the present invention includes a surface plate on which an object to be vibration-isolated is placed, an air spring that restores the displacement of the surface plate, It has an automatic pressure regulator that drives an air spring according to the displacement of the surface plate, and a plurality of non-contact units facing the top and/or bottom surface of the surface plate and spaced apart from each other so as to detect the displacement of the surface plate. This structure includes a displacement sensor, an actuator that controls the displacement of the surface plate based on difference signals detected by a plurality of non-contact displacement sensors, and a control section that drives and controls 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 includes a surface plate 4 on which precision equipment is mounted, and a surface plate 4 mounted on the lower surface of the surface plate 4 and spaced apart from each other so as to detect displacement of the surface plate 4. three non-contact displacement sensors 1, an actuator 2 that controls the displacement of the surface plate 4 based on a difference signal between the displacement amounts detected by the three non-contact displacement sensors 1, and a control unit that drives and controls the actuator 2. 3 and has a sensing lever 61 attached in contact with the lower surface of the surface plate 4, and a valve (not shown) of the automatic pressure regulator 6 controls the pressure of the surface plate 4. An air spring 5 provided in contact with the lower surface, 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.

As shown in FIG.
1 lAl2 IB), 2 actuators 2,
1 or a plurality of control units 3 (not shown in FIG. 2).

The number of non-contact displacement sensors 1 and actuators 2 to be installed is three or more non-contact displacement sensors 1 and three or more actuators 2.
There is no particular restriction as long as there are two or more.

Furthermore, the three non-contact displacement sensors 1 do not share a vertical axis perpendicular to the surface plate 4, and are spaced apart from each other on the surface facing the surface plate 4.

Of the three non-contact displacement sensors 1, one (IA) serves as a reference point. With the remaining two (IB), the difference from the reference point non-contact displacement sensor IA is detected. The actuator 2, which is connected to and controlled by the non-contact displacement sensor IB for detecting the difference via the control unit 3, is driven in the direction opposite to the displacement of the surface plate 4 by this difference. In this way, the surface plate 4 is quickly restored to a constant horizontal state (FIG. 3).

In the precision vibration isolation table according to the present invention, large vibrations are controlled in a conventional manner. That is, when the vertical movement of the 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 6E, and air is supplied to the air spring 5 from the additional tank 51. Alternatively, air is released from the air spring 5 to restore the vertically moved surface plate 4.

On the other hand, restoration of displacements such as minute inclinations that have a large effect on mounted precision equipment is done by actively driving actuators 2 controlled by a control unit 3 based on signals from three non-contact displacement sensors 1. It will be done.

The non-contact displacement sensor 1 detects the displacement of the surface plate 4 without contacting the surface plate 4, and includes an optical (LED) displacement sensor, an air variation displacement sensor, a laser displacement sensor, and an ultrasonic displacement sensor. , an eddy current type displacement sensor, and other known displacement sensors are preferably used.

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

Note that the control mechanism part that is a feature of the present invention, that is, the three non-contact displacement sensors 1, two actuators 2, and the control section 3, is different from the conventional vibration control mechanism of the vibration isolation table used. Needless to say, by adding them in parallel, 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 includes a surface plate on which an object to be vibration-isolated is placed, an air spring that restores the displacement of the surface plate, and a surface plate. It has an automatic pressure regulator that drives the air spring according to the displacement of the surface plate, so large vibrations are controlled. It is equipped with multiple non-contact displacement sensors, an actuator that controls the displacement of the surface plate based on the difference signals detected by the multiple non-contact displacement sensors, and a control unit that drives and controls the actuator. It quickly and accurately restores the surface plate even when the surface plate on which it is mounted is displaced, such as by a slight inclination, and corresponds well to the high performance and high precision of the precision equipment on which it is mounted. .

[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. 1, IA, IB, , , , Non-contact displacement sensor 2 ,
, , , , , Actuator 3 , , , , , . 4,,,,,,. 5,,,,,,. 6,,,,,. Control unit surface plate air spring automatic pressure regulator

Claims (1)

[Claims] A surface plate for placing an object to be vibration-isolated, an air spring for restoring the displacement of the surface plate, and an automatic pressure regulator for driving the air spring according to the displacement of the surface plate; a plurality of non-contact displacement sensors facing the top and/or bottom surface of the surface plate and spaced apart from each other to detect displacement; A precision vibration isolation table comprising: an actuator that controls displacement of the surface plate; and a control section that drives and controls the actuator.