JPH0681892A - Vibration remover - Google Patents

Abstract

PURPOSE:To provide a vibration remover of high performance for reducing vibration by connecting a pneumatic cylinder and a coil actuator in series to influence generating force thereof to a surface plate, and making its force points to agree. CONSTITUTION:For removing vibration while holding a position of a surface plate 2 in fixed height, air of specified pressure is input to an air input/output part 16 to also flow a current in a coil actuator 3 by a control means, and a drive shaft 22 of the surface plate 2 is energized. The coil actuator 3 thus obtained is formed into a structure of arranging an air spring 1a, damper 1b and the coil actuator 3 in series, by vertically providing a coil 3b in a base mount further fitted to float in a float fitting hole 23 provided to be recessed in the surface plate and by forming the coil actuator between itself and a magnet 3a, and force of these spring, damper and coil actuator acts in almost the same position on a table 21 of the surface plate 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to eliminate unnecessary vibrations. Vibrations for detecting vibrations and generating a force in the opposite direction to the vibrations so that the vibrations are as small as possible are used. The present invention relates to a removing device.

[0002]

2. Description of the Related Art Generally, a vibration eliminator removes the vibration of a surface plate for placing an object and performs experiments without vibration, such as an experiment using an optical element and an exposure process of a semiconductor manufacturing apparatus. It is possible to carry out on this surface plate.

There are a passive type and an active type in this vibration eliminating device. In the conventional passive type vibration eliminating device, in order to eliminate unnecessary vibration, a device utilizing the damping effect of the air pressure in the air cylinder or a vibration isolator. Some of them utilize the anti-vibration effect of rubber and the like, and each one uses the anti-vibration effect unique to the member by using a member that absorbs the vibration without detecting the vibration. In addition, in the conventional active vibration eliminator, in order to eliminate unnecessary vibration, the force generated by the air pressure in the air cylinder is controlled to reduce the vibration, and the electromagnetic force generated by the coil actuator is controlled to reduce the vibration. There are those that reduce the vibration by controlling the force generated by the piezoelectric element, and those that reduce the vibration by combining with the passive type. Generates vibration in the opposite direction to perform vibration isolation.

However, in the passive vibration eliminating mechanism, there is a natural resonance frequency between the member to be used and the mass of the surface plate or the like, and a good vibration eliminating effect cannot be obtained. Further, if the load mounted on the surface plate changes, the vibration absorbing member also deforms accordingly, so that the position of the surface plate changes and it is not possible to always maintain the levelness. On the other hand, the active vibration elimination mechanism can ensure the levelness, but in the air pressure control, the resonance frequency exists in the air cylinder and the vibration cannot be eliminated in the low frequency region. The generated force is small, and it is necessary to increase the number of actuators in order to support the surface plate and the load mounted on the surface plate, and the device becomes large. Further, the piezoelectric element has a problem in that the generated displacement is small and it is not possible to remove the vibration having large displacement in the low frequency region.

Therefore, in order to effectively remove the high frequency component and the low frequency component of the vibration, a combination of the above active type and passive type, for example, a mechanism in which an air damper, a pneumatic actuator, and a coil actuator are combined is conceivable. . In other words, with this combination mechanism, the high-frequency component of vibration is supported by the air damper, and the large weight on the surface plate is supported by the pneumatic actuator, and low frequencies below the resonance frequency that cannot be removed by pneumatic control can be removed by the coil actuator. Becomes

[0006]

However, in the mechanism in which the air damper, the pneumatic actuator, and the coil actuator are combined, the coil actuator cannot support the weight of the surface plate because the force generated by the coil actuator is small. The coil actuator must be placed in parallel with the high force pneumatic actuator. In such a case, the force points exerted by the pneumatic actuator and the coil actuator on the surface plate do not coincide with each other, which is a factor that hinders the reduction of the vibration of the position on the surface plate where the object is actually placed.

The present invention was devised to solve these problems, and by connecting a pneumatic cylinder and a coil actuator in series, the force points exerted by these generated forces on the surface plate are made to coincide, An object of the present invention is to provide a vibration removing device having high performance of reducing vibration.

[0008]

Means for solving the problems of the present invention will be described with reference to FIGS. 1 and 2 showing an embodiment of the present invention.

The vibration removing apparatus according to the present invention detects the behavior of the surface plate 2 on which the object is placed, the base 1 for supporting the surface plate 2, and the surface plate 1 to detect the movement of the surface plate 1. A coil 3 provided with a control means 4 for controlling vibration and erected on the base 1.
a, an air spring 1a provided in the base 1 for supporting the surface plate 1, a loose fitting hole 23 recessed in the surface plate 1 for loosely fitting the coil 3b, and The coil 3 having a magnet 3a embedded in the side surface of the loose fitting hole 23;
It is characterized in that the coil actuator 3 is formed between the magnet 3a and the magnet 3a by loosely fitting b into the loose fitting hole 23 provided in the surface plate 2.

[0010]

The operation of the present invention will be described with reference to FIGS.

A predetermined pressure is applied to the air input / output unit 16 by the control means 4 so that the output of the position sensor 5 of the surface plate 2 reaches a predetermined target value, that is, the table 21 of the surface plate 2 is maintained at a predetermined target height. The air spring 1a biases the drive shaft 22 of the surface plate 2 upward through the elastic portion 14 to keep the height of the table 21 constant. Further, a current is supplied to the coil actuator 3 by the control means 4 (not shown) so that the output of the vibration sensor 6 of the surface plate 2 becomes zero, that is, the vibration of the surface plate 2 becomes zero. Drive shaft 22 of surface plate 2 in the direction of eliminating vibration
Energize. At this time, since the air spring 1a, the air damper 1b, and the coil actuator 3 are arranged in series, these forces act on the table 21 of the surface plate 2 through the drive shaft 22 at substantially the same position. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 3.

FIG. 1 is a view showing an embodiment of a mechanical portion of a vibration eliminator according to the present invention. Reference numeral 1 is a column-shaped base having a hollow portion inside, and the hollow portion. Is divided into two chambers, a first chamber 11 and a second chamber 12, by a separation wall 15 having a through hole 13 of which one side is narrowed. An air input / output unit 16 is formed on the side surface of the cylinder of the first chamber 11, and air is supplied to the first chamber 11 from here. And the first chamber 11
The upper part of the elastic body 1 whose end is fixed to the side wall of the first chamber 11.
4, the first chamber 11 constitutes an air spring 1a. The elastic body 14 has a lower portion supported by a support body 18 so that the drive shaft 2 of the surface plate 2 described later is
The second mounting portion is kept in a planar shape. Further, the second chamber 12 is kept at a predetermined pressure by the air press-fitted through the through hole 13 of the separation wall 15, and thus constitutes the air damper 1b as a whole. Also, 17 is a surface plate 2 on top of the base 1.
Is a support portion for mounting the drive shaft 22 of.

A surface plate 2 has a table 21 on which an object is placed, and an air spring 1a and an air damper 1 at the bottom.
a drive shaft 22 for transmitting the urging force of b to the table 21,
Also, an end portion of the drive shaft 22 has a loose fitting hole 23 into which a coil 3b described later is loosely fitted. This surface plate 2 is an air spring 1
When a is not driven, it is placed on the support portion 17 of the base 1, and when driven, it is supported by the urging force of the air spring 1a via the elastic portion 14.

Reference numeral 3 denotes a coil actuator, which is erected on the base 1 and has a coil 3b loosely fitted in the loose fitting hole 23 of the surface plate 2 and a magnet 3a buried in the side wall of the loose fitting hole 23 of the surface plate 2.
And a magnetic body 3c. The coil actuator 3 urges the drive shaft 22 of the surface plate 2 by an electromagnetic force generated by a predetermined current supplied to the coil 3b. FIG. 2 is a block diagram showing the configuration of the present invention.
The coil actuator 3 and the air spring 1a shown in FIG.
1, a mechanism unit including a position sensor 5 and a vibration sensor 6, which are not shown in FIG. 1, and a coil actuator 3, a control unit 4 that controls the generated force of the air spring 1a, and a coil actuator 3 in response to an instruction from the control unit 4. To the air spring 1 in response to instructions from the amplifier 8 that supplies a predetermined current to the
An air pump 7 for supplying air of a predetermined pressure to a is shown. The position sensor 5 detects the height of the table 21 of the surface plate 2 and is composed of an infrared sensor or the like. The vibration sensor 6 detects the vibration of the surface plate 2 and is composed of a speed sensor or an acceleration sensor or the like. The operation of the vibration removing device configured as described above will be described based on the mechanical diagram of FIG. 1, the block diagram of FIG. 2, and the flowchart of FIG. 3 showing the operation of the control unit 4. First, the surface plate 2 is placed on the support portion 17 of the base 1 in a state where air having a constant pressure is not pressed into the air spring 1a and the air damper 1b, and the total weight of the surface plate 2 passes through the support portion 17. And is directly supported by the base 1.

When the vibration eliminator is driven, the target set value of the vibration sensor 6 is first set in the control unit 4 in S1 of FIG. 3, and the signal of the position sensor 5 is read in S2. The control unit 4 compares the target value set in S1 with the signal value of the position sensor 5, and moves the air pressure of the air spring 1a via the air pump 7 so that the surface plate approaches the position corresponding to the target value of the position sensor 6. Is increased (S3). Specifically, the position sensor 6
The air pressure should be increased in proportion to the difference between the target value and the sensor input. Next, in S4, the signal from the vibration sensor 6 is read, and in S5, a current is supplied to the coil 3b via the amplifier 8 so as to bias the surface plate 2 in the direction opposite to the vibration of the surface plate 2. Specifically, a current proportional to a signal obtained by inverting the polarity of the output of the vibration sensor 6 may be supplied to the coil actuator 3.
Since the high-frequency component of vibration is removed by the air damper 1b, the low-frequency component of vibration is exclusively detected by the vibration sensor 6. And above S2-S
By repeating the operation of 5, the surface plate 2 can be maintained in a horizontal state at a predetermined position and vibration can be prevented.

Since the present invention is constructed as described above, vibrations of the floor surface at high frequencies are eliminated by the damping effect of the air damper 1b, and for low frequencies, the resonance frequency of the air spring 1a (usually several Hz) or higher is used. With the air spring, low-frequency vibrations below the resonance frequency are removed by the force generated by the coil actuator. The present invention is based on the air spring 1 of the base 1.
The surface plate 2 is placed on a, a free-fitting hole 23 for loosely fitting the coil 3b is provided in the surface plate 2, and a magnet 3a is provided in the free-fitting hole 23 of the surface plate 2 having the recessed shape. The coil actuator 3 is built in the side wall of the coil 3b, and the coil 3b is erected on the base 1 and is loosely fitted into the loose fitting hole 23 formed in the surface plate 2 to form the coil actuator 3 with the magnet 3a. Since the coil actuator 3 provided on the air spring 1a does not have to support the weight of the surface plate 2 because of the special structure, the air damper 1b, the air spring 1a, and the coil actuator 3 are fixed in series. The board 2 can be controlled. Therefore, the point of action of the biasing force exerted on the surface plate 2 by the biasing force of the air damper 1b and the air spring 1a via the drive shaft 22 and the point of application of the biasing force exerted by the coil actuator 3 on the surface plate 2 are substantially defined. It is possible to set them at the same position, and the effect of eliminating vibration is dramatically increased.

[0018]

Since the vibration eliminating device according to the present invention has a structure in which the pneumatic cylinder and the coil actuator are connected in series, the generated forces can be applied to substantially the same position on the surface plate. Therefore, it is possible to provide a vibration eliminating device having a high performance of reducing vibrations by making the position where an object is to be placed on the surface plate substantially the same as the detection position of vibrations and the position where force is applied.

[Brief description of drawings]

FIG. 1 is an embodiment showing a mechanical portion of the present invention.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of a control unit 4.

[Explanation of symbols]

 1 ... Base 1a ... Air spring 2 ... Surface plate 3a ... Magnet 3b ... Coil 3 ... Coil actuator

Claims (1)

[Claims] 1. A vibration eliminating device comprising a surface plate on which an object is placed, a base for supporting the surface plate, and a control means for detecting a behavior on the surface plate and controlling the vibration of the surface plate. And
A coil standing on the base, an air spring arranged in the base to support the surface plate, and a loose fitting hole recessed in the surface plate for loosely fitting the coil. A coil embedded in a side surface of the loose fitting hole, and the coil is loosely fitted in a loose fitting hole formed in the surface plate to form the coil actuator with the magnet. A vibration eliminator characterized in that