JPH03129140A - Level maintenance of air spring type vibration eliminating table and fine vibration eliminating method and circuit therefor - Google Patents

Abstract

PURPOSE:To adjust an air pressure to precisely control a level at a low cost and eliminate fine vibration by outputting a vibration eliminating table level as a voltage, and analog-integrating or performing feedback compensation of the difference between the above voltage and a reference level voltage. CONSTITUTION:If a vibration eliminating table 2 is descended due to a load, a level sensor 1 detects an amount of movement with respect to a reference level, and a level differential amplifier 6 compares a level voltage with a reference level voltage. An analog integrating amplifier 8 integrates the difference, or the amplifier 8 and a feedback compensating circuit Fb perform feedback compensation to speed up the integration and level setting. A drive circuit 11 receives a level control value to which the operated output value is added, to control a control valve 7, thereby supplying compressed air to an air spring 3 to elevate the vibration eliminating table 2 up to a predetermined level. In fine vibration elimination, a vibration acceleration in the vertical direction is output as a voltage, and a control value in combination of integration, differentiation or amplification is added to the level control value. Therefore, the control valve 7 is controlled, thus adjusting an air pressure inside the air spring 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention mainly relates to holography,
Immediately and accurately detects the level displacement and minute vibrations of precision vibration isolation tables on which manufacturing equipment such as ultra-precision measuring equipment such as mirrors and semiconductor manufacturing equipment is placed, maintaining the level of the equipment and eliminating minute vibrations. This article relates to a method for maintaining the level of an air spring type vibration isolating table and isolating minute vibrations, and its circuit.

(Prior art and its circuit problems) A conventional level maintenance and minute vibration isolation circuit includes a digital circuit proposed by the applicant of this patent.

(Japanese Patent Application No. 63-35829) First, the digital level maintenance circuit (X) will be briefly explained. The level sensor (20) detects the level displacement amount of the vibration isolation table main body (31>), generates an analog displacement signal according to this displacement amount, and inputs it to the displacement pulse generator (21).Displacement pulse generation During the generation period of the displacement signal, constant pulses are generated from the displacement pulse generator (21) in accordance with a built-in internal clock (22), and are input to the addition HH23). The adder (23) counts the number of input pulses and outputs it as a displacement signal. This results in
The amount of level displacement will be understood as a digital amount.

In addition, a digital vibration isolation circuit (Y) is used to prevent minute vibrations in the vertical direction.
This zero-order digital vibration isolation circuit (Y) that isolates vibrations will be explained. A vibration sensor (24) detects minute vibrations of the vibration isolation table main body (31) caused by vibration sources such as the floor or equipment, and a minute vibration signal from the vibration sensor 24> is input to an arithmetic circuit (25). The phase of the fluctuation detection signal outputted from the arithmetic circuit (25) is inverted by 180 degrees in the next phase inverter (26), and finally the level displacement signal from the adder (23) of the bell maintenance circuit and the phase are inverted. Inverter (26
) is added to the phase inversion signal output from the level displacement/micro vibration adder (27>), and level correction is performed at the same time as disturbance control.

The output from the level displacement/l small vibration adder (27) is input to the drive circuit (28), which controls the control valve (29) and controls the pressure of the air spring (32). It looks like this.

Now, in the digital level maintenance circuit (X) as described above, the set level is used as a reference, and when the vibration isolation table main body (31) falls below the reference level (0), the air spring (32) Insert the drive circuit (28) in such a way as to lift the main body (31).
) issues an up command to the control valve <29), and the reference level (
In contrast, when the control switch (31) is located at a high position beyond ON, a down command is output.

In this case, while the up command is issued, the counter increments the clock (22) at the frequency of the built-in clock (22), and conversely, in the case of the down command, it subtracts the clock (22). ) is finally converted into a DA converter (
30>, it is converted into an analog quantity of electricity and output.

This operation moves the vibration isolation table main body (31) to the basic manual level (0
), addition and subtraction continue to be performed, so that no matter what the weight of the vibration isolation table body (31>) is, it will output an amount of electricity that matches the reference level (0).

However, in the digital method, if you simply switch the up/down command based on the set value i - point, the up/down is constantly repeated above and below the set position (reference level (O)). ) will be permanently hunted. Therefore, it is necessary to add a mechanism that sets upper and lower limits at minute distances above and below the set position (0) and stops the counting within that range.
In this range, the vibration isolation table main body (31) will move up and down freely, and a level error will occur within the upper and lower limits. Therefore, in the digital system, the reference level is ±X%.

Therefore, in order to reduce this error and increase the setting accuracy, there is a problem that a D-A converter (30) with a large number of bits must be used.Currently, it is possible to perform control with a large number of bits at a low cost. The problem is that it is not possible.

(Object of the Invention) The present invention has been made in view of the drawbacks of the conventional example, and its purpose is to enable accurate control to a set level at low cost, and in addition to this, to To provide a method for maintaining the level of an air spring type vibration isolating table and isolating minute vibrations, which also has a simple circuit configuration and excellent noise resistance, and its circuit.

(Means for Solving the Problems) In order to solve the problems of the related art, the present invention provides a method for maintaining the level of an air spring type vibration isolating table according to claim (1); In an air spring type vibration isolation table that supports the shaking table body (2) with an air spring (3), ■ the level of the vibration isolation table body (2) is sensed and output as a level voltage, and ■ this level voltage and a reference 2. Compare the level voltage and output the difference, 2. Perform analog integration on this difference, or perform feedback compensation to speed up the analog integration and level setting, 2.
) Adjust the air pressure inside.

The method for maintaining the level of an air bubble vibration isolator table in Claim TrJ (2) adopts the following technical means: In the method for maintaining the level of an air spring type vibration isolation table in 1), ① Add the feedforward control value based on prior data to the analog integral value and the feedback compensation value to obtain the level control value.

The method of maintaining the level and isolating minute vibrations of the air spring type vibration isolating table according to claim (3) is as follows: ■ Level sensing of the vibration isolating table body (2) is performed to detect the level. In the air spring type vibration isolator according to claim (1) or (2), the vibration isolator is controlled by: ■ outputting the vertical vibration acceleration of the vibration isolator main body (2) as a vertical acceleration voltage; and ■ outputting this vertical acceleration voltage. Any one of integration, differentiation, and amplification, or a combination of two or all of these, or vibration damping feedback compensation by phase compensation, ■The vertical vibration control value and claim (1) or (2) The air pressure in the air spring is adjusted to correspond to the sum of the level control value.

The level maintenance circuit (M
), In the air spring type vibration isolator according to claim (1) or (2), in which the level is controlled by level sensing of the vibration isolator main body (2), ■ the vertical direction of the vibration isolator main body (2) is The vibration acceleration is output as a vertical acceleration voltage, and the vertical acceleration voltage is integrated, differentiated, and amplified, or a combination of two or all of these, or vibration damping feedback compensation is performed using fα phase compensation. (1) Adjust the air pressure in the air spring (3) so as to correspond to the phase between the vertical vibration control value and the level control value of claim (1) or (2).

The level maintenance circuit for an air spring type vibration isolator table according to claim <5> employs the following technical means to carry out the level maintenance method for an air spring type vibration isolator table according to claim (1). .

■In an air spring vibration isolator that supports the vibration isolator body (2) for mounting equipment with an air spring (3), ■senses the level of the vibration isolator body (2) and outputs it as a level voltage. a level sensor (1); ■ a level differential amplifier (6) that compares the level voltage output from this level sensor (1) with a reference level voltage and outputs the difference; ■ a level differential amplifier ( 6), or a level analog integrating amplifier (8) and a feedback compensation circuit (Fb) for accelerating level setting; The control valve (7) adjusts the air pressure in the vertical air spring (3) in accordance with the level control it value of (b)>.

The level maintenance circuit of the air spring type vibration isolating table according to claim (6) adopts the technical means as follows.
In order to carry out the method for maintaining the level of an air spring vibration isolator table according to claim (2), claim (5) includes: (1) an analog integrating amplifier (8) and a feedback compensation circuit (Fb) for speeding up level setting.
) In the level maintenance circuit of the air spring type vibration isolation table, ■1.1 is added to the feed-forward control circuit (Ff) that performs feed-forward control based on the 1Y previous data.
■ Feedback supplementary 1 for feed forward control value? T
The value is added to the value and the analog integral value to obtain the level control value.

The level maintenance 4 of the air spring type vibration isolator according to claim ri (7) and the vibration isolating circuit for minute vibrations adopt the technical means t3. In order to carry out the method for maintaining the level of the table, ■ The level maintaining circuit (M) of the air spring type vibration isolating table according to claim (5) or (6) that performs level control includes the vibration isolating table main body (2).
a vertical acceleration sensor (13) that detects vibration acceleration in the vertical direction; a vertical vibration integration amplifier (14) that integrates the output of the vertical acceleration sensor (13); and a vertical vibration differentiation amplifier that differentiates the output. (15) and a combination of one or more of the vertical vibration proportional amplifiers (16) that amplify the output, or a vibration damping feedback compensation circuit (Fb) using phase compensation. ) (15) (16) or the air spring (2) so as to correspond to the sum of the vertical vibration control value from the damping feedback compensation circuit (SFb) and the level control value of claim (5) or (6). It consists of a control valve (7) that adjusts the air pressure inside.

The technical means of claim (8) for maintaining the level of the air spring type vibration isolating table and the vibration isolating circuit for micro vibrations is the same as the level maintaining circuit for the air spring type vibration isolating table of claim (4). In addition, in order to implement the method for isolating minute vibrations, ■Claim 7 for vibration damping feedback compensation using phase compensation for vertical vibrations (7) Level maintenance of air spring type vibration isolator table and vibration isolating circuit for minute vibrations In this case, ■ Add a damping feedforward control circuit (Sm) that performs feedforward control based on prior data, ■ add the vibration damping feedforward control value to the feedback compensation value to obtain a vertical vibration control value, and ■ add this It is comprised of a pressure control valve (7) that adjusts the air pressure within the air spring (2) to correspond to the sum of the vertical vibration control value and the level control value of claim (5) or (6).

・We have adopted technical measures such as:

(Function) First, level maintenance in the method of the present invention will be explained. When a load is applied to the vibration isolation table main body (2), the vibration isolation table main body (2)
I'll explain what happens if it sinks. On the other hand, when the load is removed and the vibration isolator body (2) rises, the opposite is true, and when the load moves and the vibration isolator body (2> tilts), either of these cases is compounded. It will be applied.

■The load is applied to the vibration isolator body (2>), and the vibration isolator body (2>
When the level sensor (1) sinks, the amount of vertical movement relative to the reference level is detected by the level sensor (1).

(2) The level voltage output by the level sensor (1) is input to the level differential amplifier (6) and compared with the reference level voltage.

■At this time, the reference level voltage becomes higher than the level voltage,
The output of the level differential amplifier (6) becomes positive.

■Is that positive difference the analog level f? ? 5) Analog integration is performed in the amplifier (8), or feedback compensation is performed in the analog integration amplifier (8) and feedback compensation ports 1 to 3 (Fb) to speed up analog integration and level setting, or the feedback compensation □The feedforward control output value is added to the value.

■The level control value obtained by adding the output value of the back compensation circuit (Fb) in the analog integrating amplifier (8) or F1, or the output value processed by the feedforward control circuit (Ff) to this is the output value of the drive circuit (11 ) to control the control valve (A), and the control valve (7) receives this control and supplies compressed air to the air spring (3) to lift the vibration isolation table body (2) to a predetermined level. shall be.

■When the vibration isolation table main body (2) begins to lift, the output constant voltage of the level sensor (1) gradually increases, approaches the Hanawa quasi-level voltage, and finally becomes equal, and the output of the level perturbation amplifier (6) becomes zero. Become.

■The output value of the level integrating amplifier (8), or the sum of the level integrating amplifier (8) and the feedback compensation circuit (Fb), or the feedforward control circuit (Ff) is held at this point, and one vibration isolation script is used. (2) is fixed at a position matching the reference level (0).

After 0 or more operations, the main body of the vibration isolation table (2)
reaches the reference level (0) and is fixed. At this time, since the output of the level integrating amplifier (8>) is an analog value, it accurately matches the reference level (0) and does not generate errors unlike conventional digital control.

In addition, in the method for isolating minute vibrations of an air spring type vibration isolation table, ■ output the vertical vibration acceleration of the vibration isolation table main body (2) as a vertical acceleration voltage, and ■ integrate and differentiate this vertical acceleration voltage. or control of any one of amplification to a combination of two or all of these, or damping feedback compensation using a damping feedback compensation circuit (IIFb), or the above-mentioned i+lI F
A feedforward control value is added to the feedback compensation, ■ the vertical vibration control value is added to the level control value of claim (1), and the control valve (7) is controlled by the drive circuit (11) to compensate for both. Adjust the air pressure in the air spring <3> to correspond to the sum.

This makes it possible to maintain the level and control minute vibrations.

Note that although the integration by the level integrating amplifier (8) is analog integration, other processing may be analog processing or digital processing.

(hereinafter referred to as plan) (Example ) Hereinafter, the circuit of the present invention will be explained with reference to the drawings.

The vibration isolation table consists of a vibration isolation table main body (2), which is a surface plate part for mounting manufacturing equipment such as holography sets, electron microscopes, and ultra-precision measurement equipment such as semiconductor manufacturing equipment, and a vibration isolation table main body (2).
2) and three to four air springs (3) for supporting the air springs (3). The air spring (3) has a rubber spring part (
The main body of the vibration isolation table (
A level sensor <1> that is close to and separated from 2) is installed near the vibration isolation table main body <2), and an analog power proportional to the distance is input to one end of the level differential amplifier (6). It is supposed to be done. For example, a J1° contact analog output type proximity sensor is used as the level sensor (1). A reference level voltage corresponding to the reference level <0) of the vibration isolation table main body (2) is input to the other end input of the level differential amplifier (6). At the output terminal of this level differential amplifier (6), an analog level integrating amplifier (8) alone, or an analog level integrating amplifier (8) and a feedback compensation circuit (Fb) for speeding up level setting, or the feedback compensation value A feed forward control circuit (Ff) based on prior data to increase the vibration damping effect at the initial motion is connected, and these are further connected to a drive circuit (11), and this drive circuit (
11), the air pressure in the vertical air spring (3) is adjusted to the control valve (
It is adjusted by (a).

Here, in the case of only this level integrating amplifier (8>), the vibration isolation table main body (2) is the level integrating amplifier (8).
It returns to the reference level (0) according to the time constant of , and the return speed cannot be said to be very quick.

However, the level integrating amplifier (8) and the feedback compensation circuit F! This is improved when using 8(Fb).

As shown in FIG. 1, the feedback compensation circuit (Fb) is composed of a level proportional amplifier (9) and/or a level differential amplifier (lO) in the case of the second example;
Examples are level proportional amplifier (9) and phase compensation circuit (10')
This is the case where the

In the case of the first example, ■Level integral amplifier (8>10 level proportional amplifier (9)■
Level integral amplifier (8) 10-level differential amplifier (10) ■
The combination is a level integral amplifier (8), a ten-level proportional amplifier (9), a ten-level differential amplifier (10), and a second
In the case of the example, the combination is: (1) a level integral amplifier (8) a ten-level proportional amplifier (9) a half-phase compensation circuit (<10').

In order to speed up the above-mentioned level setting, the time constant of integration can be increased by adding proportional, differential, or phase compensation in addition to analog integration of relative displacement.

In addition, the time constant of the air spring <3) is higher than the frequency range (for example, 0
．． 111z or higher) and, conversely, by feeding back the proportional component to the low frequency region, effective relative displacement control becomes possible. This allows for displacement vibrations in the low frequency band that are difficult to achieve by feeding back information from the vertical acceleration sensor (13), which will be described later. It is possible to control the gentle sway in direction.

Furthermore, there is a limit to reducing the initial response to disturbance using only the feedback control described above, and it is effective to add feedforward control to improve this. The case where the feedforward control circuit (Ff) is used will be explained below. The first method of the feedforward control circuit (Ff) is to create a pattern in advance of level fluctuations caused by the driving of equipment or devices to be controlled, and
etc., and instantly selects the most optimal pattern by capturing the initial signal indicating that the level fluctuation has occurred, and controls according to the pattern according to the input of the level fluctuation to the vibration isolation table main body (2). The second method is to control the vibration isolation table by controlling the magnitude of the level fluctuation that is to be input to the vibration isolation table main body (2) without creating the above-mentioned pattern in advance. Measurement is performed immediately before input to the main body (2), and this is calculated to control the control valve (7>) in real time.

This improves the problem that feedback control alone was not able to adequately control the level at the time of initial movement.

The control valve (7) has its output side connected to the air tank (4>), and its input side connected to the air pressure source (10) via a regulator (not shown). Like a servo valve, the opening degree of the valve is accurately controlled by the input current, and the pressure within the air tank (4) is accurately maintained.

This level sensor (1), level differential amplifier (6), analog level integral amplifier (8), level proportional amplifier (9)
), the level differential amplifier (10) (or the feed punctum compensation circuit (Fb) or the feed forward control circuit (Ff) added to it), and the control valve (7) are 1 in the center of the vibration isolation table main body (2)
It is sufficient to simply arrange the air springs in pairs, and if level control and tilt control are to be performed, each air spring (3) must be installed at at least three locations.

Next, the functions of the analog level integral amplifier (8), the level proportional amplifier (9), and the level differential amplifier (10) will be explained.

The analog level integrating amplifier (8) multiplies the difference by
This is integrated and outputted as an analog output (K), and the control valve (7) is controlled by the drive circuit (11) to return the vibration isolation table body (2) to the reference level according to the time constant.
(i.e., the drive circuit (11) so that the output potential of the level sensor (1) matches the reference level potential.
The control valve (7) is actuated by the level differential amplifier (6).
) and maintain this state. ) is shown.

As mentioned above, the level proportional amplifier (9) doubles the output of the level differential amplifier (6) to speed up the rise of the level return, and also makes the level 1? The control valve (7) is controlled by the drive circuit (11) so as to suppress the vertical fluctuation based on the i l1ffi and to accurately match the potential to the reference level.

The level differential amplifier (10) works to stiffen the air spring and reduce the responsiveness of level displacement, and generally responds to level fluctuations (vertical fluctuations) at frequencies higher than the time constant of the air spring. It has a control effect.

The phase compensation circuit (10') is connected to the level differential amplifier (10').
It functions in the same way as 0>.

The feedback compensation circuit (Fb) is connected to the level proportional amplifier (9) and/or the level differential amplifier (lO), the level proportional amplifier (9), and the phase compensation circuit Ho', and is connected to a bypass filter, a low-pass It has various filter functions such as a filter and a notch filter, and performs phase compensation with frequency weighting.

The function of the feedforward control circuit (Ff) is as described above.

However, when a load is applied to the vibration isolation table main body (2) and the vibration isolation table main body (2) sinks, the load is removed and the vibration isolation table main body (2)
When the vibration isolation table body (2
> is tilted, the amount of vertical movement relative to the reference level <0) is detected by the level sensor (1), output as a level voltage and input to the level differential amplifier (6), and the reference level voltage compared to

When the vibration isolation table body (2) is lower than the reference level (0>), the reference level voltage becomes higher than the level voltage, the output of the level differential amplifier (6) becomes positive, and the positive difference is Analog level integrating amplifier/13) or input to analog level integrating amplifier <8> and feedback compensation circuit (Fb), and analog level integrating amplifier (8)
In the case of the analog level integral amplifier (8) and the feedback compensation circuit (Fb), the sum of the analog integral value and the feedback compensation value is output and input to the drive circuit (11). Furthermore, in order to improve the control effect during the initial operation, a feed forward control circuit (Fr
), and the feedforward control value in either of the two cases described above is added to the feedback complement Ml. As a result, the control valve (7) is controlled by the drive circuit (11), supplies compressed air to the air tank (4) of the air spring (3), and lifts the vibration isolation table main body <2>. Vibration isolation table body (
2) starts to rise, the output voltage of the level sensor (1) gradually increases, approaches the reference level voltage, and finally becomes equal, and the output of the level differential amplifier (6) becomes zero. The input value to the drive circuit (11) is stable at this point,
The vibration isolation table main body <2> is stably maintained at a position corresponding to the reference level (0). If the vibration isolation table body (2) is higher than the reference level, conversely, the low level differential amplifier (6)
The output will be negative. Then, as mentioned above, when the vibration isolation table main body (2) moves up and down and reaches the reference level (0), the output of the level differential amplifier (6> becomes zero, and the level proportional amplifier (9) etc. As a result, it is fixed at the base level (0) without any shaking.

Next, we will discuss isolation of minute vibrations in air spring type vibration isolation tables. This vibration isolating table main body (2) is subjected to the level control described above, and in addition to this, it is possible to perform vibration isolation of minute vibrations. That is, as shown in FIG. 2, a vertical acceleration sensor (
13) is placed in the center of the vibration isolating table body (2>), which includes a vertical vibration integrating amplifier (14) that integrates the output of the vertical acceleration sensor (13), and a vertical vibration differential amplifier (14) that differentiates the output. Any one to two of an amplifier (15) and a vertical vibration proportional amplifier (16) that amplifies the output.
A damping feedback compensation circuit (SFb) using phase compensation or phase compensation is provided.

Here, the combination of these amplifiers will be explained as follows.

■Vertical vibration integral amplifier (14) only, ■Vertical vibration differential amplifier (15) only, ■Vertical vibration proportional amplifier (16) only, ■Vertical vibration integral amplifier (14) and vertical vibration differential amplifier (15) ) combination, ■ combination of vertical vibration integral amplifier (14) and vertical vibration ratio steel amplifier (1θ), ■ combination of vertical vibration differential amplifier (15) and vertical vibration proportional amplifier (16), ■ vertical direction Vibration integral amplifier (14), vertical vibration differential amplifier (15), and vertical vibration proportional amplifier (16)
A combination of.

The outputs from these amplifiers are input to the drive circuit (11) together with the level control signal mentioned above, which controls the control valve (7) to adjust its valve opening, and controls the air tank (4) of the air spring (3).
) Adjust the pressure.

Here, 8 of each amplifier! To explain the function, the vertical vibration integrating amplifier (14) converts the vertical acceleration (ri) into 1
It doubles, integrates (K, .±), and outputs (father, K3, ★).

Now, controlling the valve opening with the control valve (7) to control the flow rate and controlling the pressure of the air spring (3) corresponds to integrating the flow rate.

Expressing this as a formula, a/(1+Ta-3)! :i 1 /5 --- (
1) However, the high frequency silver j than the time constant of the air spring (3)
While dl, S>1/Ta.

Therefore, when the output value (2 K, · temple) is input to the drive circuit (1) and the air spring (3) is controlled, the output value is further integrated, and the vibration isolating table body (2) is The absolute displacement of the vibration isolation table main body (2) is controlled at that level regardless of the level.This can be expressed by the following equation.

Father,...★, f-X-,...old... (2) In other words, it absorbs and isolates minute vibrations from the floor surface or from mounted equipment. It works to eliminate the vibration of the table, and in terms of spring characteristics, it has the same function as ``stiffening the spring.''

The vertical vibration proportional amplifier (16) amplifies the acceleration six times, and serves to increase the damping efficiency of the air bubble (3).

The vertical vibration differential amplifier (I5) multiplies the acceleration (Sh) by 6, differentiates it (K, ・S), and outputs it. ) to control the air flow (3), but this is the vibration isolation table body 2)
7, which acts as if the mass were increased, and this can be expressed as the following equation.

k・K,・S-Teraichi・K,・・・・・・・・・(3)
By using the above amplifier, minute vibrations can be controlled according to the characteristics of the amplifier.

Furthermore, the functions of the damping feedback compensation circuit (SHb) and the damping feedforward control circuit <SFr> are substantially the same as those of the feedback compensation circuit (Hb) and feedforward control circuit (Ff) described above. The explanation will be omitted.

Feedforward control is almost the same as level restoration/exposure, and there is a method to eliminate vibration by selecting a predetermined damping pattern according to the type of vertical vibration.
There is a method of suppressing the vibration by catching the magnitude of the vibration that is being input in advance and inputting a control signal to the drive circuit (11) to cancel the vibration.

(Effects) As shown in claim (1), the level maintenance method of the air spring type vibration isolator of the present invention is an air spring type vibration isolator in which the body of the vibration isolator for mounting equipment is supported by an air spring. At the stand, the level of the vibration isolator stand is sensed and output as a level voltage, this level voltage is compared with a reference level voltage, the difference is output, and this difference is used for analog integration or analog integration and level setting. Perform feedback compensation to speed up the process,
The air pressure in the air spring is adjusted to correspond to these level control values, but since it is analog integration, there is an error in the vibration isolation table body being free above and below the reference level, unlike the conventional digital method. It is possible to fix the main body of the vibration isolation table at an accurately set reference level without causing any area, and even though the accuracy of the control 11 can be greatly improved as mentioned above, it is extremely low cost and simple. A dark circuit is fine,
- Also, because it requires only an extremely simple circuit, it has many advantages over digital systems, such as superior noise resistance. Furthermore, since differential, proportional, or feedback compensation is performed, it is possible to speed up the level settling of the vibration isolation table body by speeding up the time constant of the integration, and it is also possible to set the differential component in a higher frequency region than the time constant of the air spring. By feeding back the proportional component to the low frequency region, it is possible to control the vertical vibration (=displacement vibration) at low frequencies.

In addition, claim (2) provides claim (1) for performing feedback compensation to speed up analog integration and level setting.
), the level control value is obtained by adding the feedforward control value based on prior data to the analog integral value and the feedback compensation value, so the disturbance is not input. Feedback i! starts control after It is possible to effectively perform initial motion control, which is difficult with the III control, and by combining the two, effective level control from the initial motion is possible.

Further, in claim (3), in the air spring type vibration isolator according to claim (1) or (2), in which the level is controlled by level sensing of the vibration isolator main body, the vibration acceleration in the vertical direction of the vibration isolator main body is controlled. is output as a vertical acceleration voltage, and this vertical acceleration voltage is integrated, differentiated, amplified, or a combination of two or all of these, or is subjected to vibration damping feedback compensation using phase compensation. Since the air pressure in the air spring is adjusted to correspond to the sum of the vertical vibration control value and the level control value of claim (1) or (2), in addition to level control, there is an active function for vertical vibration. Control becomes possible.

Claim (4) provides a method for maintaining the level of an air spring type vibration isolation table and isolating minute vibrations according to claim (3), which performs damping feedback compensation using phase compensation for vertical vibrations, based on prior data. Since the feedforward control value obtained is added to the feedback compensation value to obtain the level control value, the above-mentioned feedforward control can be performed even for vibrations in the vertical direction, and effective active control is possible from the initial movement.

Furthermore, the methods of claims (1) to (4) can be implemented by the circuits of claims (5) to (8).

[Brief explanation of the drawing]

Figure 1(a)...Block circuit for level maintenance using the analog integrating amplifier of the present invention.Figure 2(b)...Other block circuit diagram for level maintenance of the present invention.Figure 2. ...Block circuit diagram for maintaining level and removing minute vibrations in the present invention Fig. 3...Block circuit diagram of conventional example ([)...Feedforward III control circuit (level side) (llb)...・Feedback compensation circuit (level side) (Sllf)...Vibration suppression feedforward control circuit (horizontal side) (Sllb)...Vibration suppression feedback compensation circuit (horizontal side) (M)...Level maintenance circuit (N )
...Minute vibration isolation circuit (1)...Level sensor (2)...Vibration isolation table body (3)...Air spring (4)
...Air tank (5)...Spring part (6)...
・Differential amplifier (7)...Control valve (8)...Level integral amplifier (9)...Level proportional amplifier (10)...Level differential amplifier (11)...Drive circuit <12> ... Air pressure source (13) ... Vertical analog acceleration sensor (14)
... Vertical vibration integral amplifier (15) ... Vertical vibration differential amplifier (16) ... Vertical vibration proportional amplifier (10°) ... Phase compensation circuit (Hf) ... Feedforward control Circuit (level side) (Hb)...Feedback compensation circuit (level side)
(S)If)...Vibration damping feedforward control circuit (
Horizontal side) (S) Ib)... Vibration suppression feedback compensation circuit (Horizontal side) (M)... Level maintenance circuit (N)...
Micro-vibration isolation circuit (1... Level sensor/ (2... Vibration isolation table body (3)... Air spring (4...
...Air tank (5)...Spring part (6)...Differential amplifier 7)...Control valve (8)...Level integral amplifier (9)...Level proportional amplifier (10...Level Differential amplifier (10″)...Phase compensation circuit (11)...Drive circuit (12)...Air pressure source (13)...Vertical analog acceleration sensor (14)
... Vertical vibration integral amplifier (15) ... Vertical vibration differential amplifier (16) ... Vertical vibration proportional amplifier procedure correction method) % formula % Relationship with the case of the person making the amendment Address of the patent applicant 5-17 Minamizukaro-cho, Amagasaki City, Hyogo Prefecture Name: Patent Equipment Co., Ltd. Representative: Kozo Kaimoto

Claims (8)

[Claims] (1) In an air spring type vibration isolator that supports the main body of the vibration isolator for mounting equipment with an air spring, the level of the vibration isolator is sensed and output as a level voltage, and this level voltage and a reference level voltage are This difference is used for analog integration, or feedback compensation is performed to speed up the analog integration and level setting, and the air pressure in the air spring is adjusted to correspond to these level control values. A method for maintaining the level of an air spring type vibration isolation table, which is characterized by: (2) In the level maintenance method for an air spring type vibration isolator table according to claim (1), in which feedback compensation is performed to speed up analog integration and level setting, the feedforward control value based on prior data is integrated by analog integration. A level maintenance method for an air spring type vibration isolation table, characterized in that the value is added to a feedback compensation value to obtain a level control value. (3) In the air spring type vibration isolation table according to claim (1) or (2), in which the level is controlled by level sensing of the vibration isolation table body, the vertical vibration acceleration of the vibration isolation table body is expressed as a vertical acceleration voltage. This vertical acceleration voltage is integrated, differentiated, and amplified, or a combination of two or all of these is performed, or vibration damping feedback compensation is performed using phase compensation, and the vertical vibration control value and claim are calculated. A method for maintaining the level of an air spring type vibration isolation table and isolating minute vibrations, characterized by adjusting the air pressure in the air spring so as to correspond to the sum of the level control value in item (1) or (2). (4) In the method for maintaining the level of an air spring type vibration isolation table and isolating minute vibrations according to claim (3), which performs vibration damping feedback compensation by phase compensation for vertical vibrations, feed-forward control is performed based on prior data. A method for maintaining the level of an air spring type vibration isolation table and isolating minute vibrations, characterized in that a value is added to a feedback compensation value to obtain a level control value. (5) In an air spring type vibration isolation table that supports a vibration isolation table body for mounting equipment with an air spring, a level sensor that senses the level of the vibration isolation table body and outputs it as a level voltage;
A level differential amplifier that compares the level voltage output from this level sensor with a reference level voltage and outputs the difference, and a level analog integrating amplifier or level analog integrating amplifier that integrates the output of the level differential amplifier. and a feedback compensation circuit for speeding up level settling, and a control valve that adjusts or reduces the air pressure in the vertical air spring in response to the level control value of the amplifier or feedback compensation circuit. A level maintenance circuit for an air spring type vibration isolation table. (6) Feed-forward control that performs feed-forward control based on prior data in the level maintenance circuit for the air spring type vibration isolation table according to claim (5), which includes an analog integrating amplifier and a feedback compensation circuit for speeding up level setting. A level maintenance circuit for an air spring type vibration isolation table characterized by adding a circuit and adding a feedforward control value to a feedback compensation value and an analog integral value to obtain a level control value. (7) The level maintenance circuit of the air spring type vibration isolation table according to claim (5) or (6) that performs level control includes a vertical acceleration sensor that detects vibration acceleration in the vertical direction of the vibration isolation table body; A combination of one or more of a vertical vibration integrating amplifier that integrates the output of the directional acceleration sensor, a vertical vibration differential amplifier that differentiates the output, and a vertical vibration proportional amplifier that amplifies the output, or phase compensation. A damping feedback compensation circuit is added to the air spring so as to correspond to the sum of the vertical vibration control value from these amplifiers or the damping feedback compensation circuit and the level control value of claim (5) or (6). A vibration isolating circuit for maintaining the level of an air spring type vibration isolating table and for isolating minute vibrations, the circuit comprising a control valve that adjusts or reduces the air pressure of the air spring type vibration isolating table. (8) Feed-forward control based on prior data in the level maintenance and minute vibration isolating circuit of the air spring type vibration isolating table according to claim (7), which performs vibration damping feedback compensation by phase compensation for vertical vibrations. A damping feedforward control circuit for performing the above is added, and the damping feedforward control value is added to the feedback compensation value to obtain a vertical vibration control value, and this vertical vibration control value and claim (5) or (
6) A vibration isolation circuit for maintaining the level of an air spring type vibration isolation table and for isolating minute vibrations, characterized by comprising a control valve that adjusts or reduces the air pressure in the air spring so as to correspond to the sum of the level control value of (6). .