JPH0765635B2 - Vibration control device for vibration isolation table - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to vibrations from the installation floor of equipment such as semiconductor manufacturing equipment and electron microscopes that adversely affect the yield of products and measurement and observation accuracy due to vibrations from the installation floor. The present invention relates to a vibration control device for a high-precision vibration isolation table that shuts off the vibration.

[Prior art]

In semiconductor manufacturing equipment, electron microscopes, etc., vibration from the installation floor adversely affects the yield of products and the accuracy of measurement and observation, so a vibration isolation device is used to block the vibration of the installation floor. As this vibration isolator, there has been one in which the vibration isolation base floor plate is supported by vibration isolation rubber or an air spring to prevent the vibration of the installation floor from being transmitted to the vibration isolation base floor plate.

[Problems to be Solved by the Invention]

As described above, the vibration mass of the spring-mass is formed in the vibration isolation table vertically supported by using the vibration proof rubber and the air spring. Therefore, at a frequency considerably higher than the resonance frequency, there is a vibration isolation effect, but at a frequency below the resonance frequency,
There is no vibration isolation effect. Also, these support materials are
Since it has a lateral rigidity greater than that in the supporting direction, a resonant system is formed in the horizontal direction even in the vertical supporting. Since its natural frequency in the horizontal direction is equal to or higher than that in the vertical direction,
The vibration isolation effect in the horizontal direction is inferior to that in the vertical direction. By the way, the natural vibration of the building in the horizontal direction is lower than that in the vertical direction,
Since microtremors of the ground are constantly transmitted in the horizontal direction, a vibration isolation effect in the horizontal direction is particularly required in a vibration isolation table for installing a semiconductor manufacturing apparatus, an electron microscope, or the like. Also,
In order to improve the vibration isolation effect in the horizontal or vertical direction, there are some examples in which an electromagnetic solenoid or a hydraulic pneumatic cylinder is used as an actuator together with an air spring to perform active control. Some restraint is applied in two directions perpendicular to the direction, and the vibration isolation effect in directions other than the control direction is diminished.

The present invention has been made in view of the above point, and has a spring action using a vibration isolation rubber or an air spring or the like that suspends a vibration isolation base floor plate and blocks microvibration from the floor on which the vibration isolation base is installed. Another object of the present invention is to provide a magnetic attraction type vibration damping device in parallel with the device to provide a vibration damping device for a vibration isolation table having a high vibration isolation action.

[Means for Solving the Problems]

In order to solve the above problems, the present invention has a vibration damping device for a vibration isolation table configured as follows.

An anti-vibration device having a spring action that suspends a vibration isolation table floor plate to block minute vibrations from the vibration isolation table installation floor. In addition to attaching the magnetically made yoke bar to the vibration isolation table installation floor or the vibration isolation floor plate, a magnetic material yoke bar is attached to the tip of the yoke bar, and a gap is formed from the yoke bar and the yoke plate. Is fixed to the floor plate of the anti-vibration table and the member to which the inner yoke bar of the floor of the anti-vibration table is not attached, and is equipped with an exciting coil that generates a magnetomotive force in a direction orthogonal to the yoke bar and the yoke plate. An electromagnet and an acceleration sensor for detecting the acceleration of the vibration isolation floor plate are provided, and the magnetic attraction force acting between the yoke bar and the yoke plate and the fixed electromagnet is controlled so that the output from the acceleration sensor is constant. A control provided with a controller having a compensation circuit and a power amplifier. Characterized in that a control device.

Further, in the pressure chamber of the air spring, a magnetic yoke bar is attached to either the air spring mounting member of the vibration isolation table floor plate or the air spring mounting member of the vibration isolation table installation floor, and at the tip of the yoke bar. Attach a yoke plate made of magnetic material,
A gap is provided from the yoke bar and the yoke plate, and the air spring mounting member of the vibration isolation table floor plate and the inner spring rod of the air spring mounting member of the vibration isolation table installation floor are fixed to the member not attached, and the yoke bar And a fixed electromagnet having a coil that generates a magnetomotive force in a direction orthogonal to the yoke plate, and acts between the yoke bar and the yoke plate and the fixed electromagnet so that the output from the acceleration sensor is constant. It is characterized by controlling the magnetic attraction force.

Further, in the compensation circuit of the control device, α ₁ × M ₀ (M ₀ is the mass of the vibration isolation base floor plate per vibration isolator), α ₂ × for acceleration, velocity and displacement of the vibration isolation base floor plate, respectively. Feedback coefficient α _{1 of} the control circuit for feeding back the sum of the values obtained by multiplying C ₀ (C ₀ is the damping coefficient of the vibration isolator) and α ₃ × K ₀ (K ₀ is the spring constant of the vibration isolator) as the magnetic attraction force. , Α ₂ , α
_{3 is set} to 10 or more.

Further, in the compensation circuit of the control device, a resistor for detecting the current of the exciting coil is connected between the exciting coil and the ground, and a signal from the resistor is fed back to the input of the power amplifier. .

[Operation] As described above, a magnetic attraction type vibration damping control device is provided alongside a vibration damping device such as a vibration damping rubber or an air spring, and an acceleration sensor for detecting the acceleration of the vibration isolation floor plate is used. Since the magnetic attraction force acting between the yoke bar and the yoke flat plate and the fixed electromagnet is controlled so that the output of the Since the action is also improved, it is possible to realize a vibration isolation table having a high vibration isolation effect.

Further, the feedback coefficients α ₁ , α ₂ , α of the control circuit for feeding back the magnetic attraction force of the compensating circuit to the vibration isolation base plate.
_By setting ₃ to 10 or more, as will be described in detail later, the damping effect at frequencies below the natural frequency becomes remarkable.

Further, since a resistor for detecting the current of the exciting coil is connected between the exciting coil and the ground and the signal from the resistor is fed back to the input of the power amplifier, the slew rate of the power amplifier is increased, and the exciting coil is increased. A current that is proportional to the input voltage of the power amplifier will flow through.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing the structure of a vibration damping device for a vibration isolation table according to the present invention. In FIG. 1, reference numeral 1 is a vibration isolation table floor plate, 2 is a vibration isolation table installation floor, and the vibration isolation table floor plate 1 is suspended by air springs 3 and 4 and supported on the vibration isolation table installation floor 2. In the pressure chamber of the air spring 4, the bar member 13 is fixed to the air spring mounting member 11 of the vibration isolation table floor plate 1 below the air spring mounting member 12 of the vibration isolation table mounting floor 2 and at a right angle to the bar member 13. A yoke 14 made of a magnetic material such as a silicon steel plate is fixed to a predetermined position of the rod member 13 and a yoke flat plate 15 made of a magnetic material is also attached to the tip of the rod member 13.
Is fixed. The casing 18 attached to the air spring attachment member 12 facing the yoke 14 has an electromagnet stator 16
Is fixed, and an exciting coil 17 that gives a magnetomotive force to the electromagnet is attached to the electromagnet stator 16. The exciting coil 17 on the horizontal plane is for controlling the horizontal vibration of the bar member 13, and as shown in FIG. 2, a pair of exciting coil 17A and exciting coil 17C are formed depending on the necessity of control. There is also a case where they are arranged to face each other and to face the pair of exciting coils 17B and 17D in the Y direction orthogonal to the straight line X connecting the exciting coils 17A and 17C. That is, 2 which are orthogonal
Two sets of opposing excitation coils may be provided for directional control. Electromagnet stators 19a.19b fixed to the casing 18 are provided so as to face the upper and lower surfaces of the yoke plate 15, and each of the electromagnet stators 19a.19b is excited by a magnetomotive force applied to the electromagnet. Coils 20a and 20b are provided. Reference numeral 21 is an acceleration sensor for detecting the horizontal acceleration of the vibration isolation base floor plate 1, and 22 is an acceleration sensor for detecting the vertical acceleration of the vibration isolation base floor plate 1. Further, the acceleration sensor 21 is controlled by X, X, as shown in FIG.
Two acceleration sensors 21A and 21B are provided in the direction orthogonal to Y. In the vibration damping device for the vibration isolation table having the above structure, when the vibration isolation table installation floor 2 vibrates, the vibration isolation table floor plate 1 is vibrated according to the spring characteristic of the air spring 4. The acceleration of the vibration isolation base floor plate 1 at this time is detected by the acceleration sensor 21 and the acceleration sensor 22.

Based on the acceleration of the vibration isolation base floorboard 1 detected by the acceleration sensor 21 and the acceleration sensor 22, a configuration example of a control device that generates a magnetic attraction force to control the vibration of the vibration isolation base floorboard 1 is shown in FIGS.
Shown in the figure. FIG. 4 is a block diagram showing the configuration of the control device when one power source is used as the power source of the power amplifier, and FIG. 5 is a block diagram showing the configuration of the control device when both power sources are used as the power source of the power amplifier. It is a figure.

In the control device having the configuration shown in FIG. 4, the acceleration sensor 21 detects the acceleration of the bar member 13 fixed to the vibration isolation base floor plate 1,
A linear detection circuit that adds the signal V _B for creating a bias magnetic field to the output signal from the compensation circuit 31 that is guided to the compensation circuit 31.
It leads to 32a, and the signal of the voltage of the + side is obtained. Also, the compensation circuit 3
A signal V _B for creating a bias magnetic field is added to the signal obtained by inverting the output signal from 1 and the signal is guided to the linear detection circuit 32c to obtain a + side voltage signal. The output signals from the linear detection circuits 32a and 32c are respectively guided to the power amplifiers 33a and 33c of the single power supply, and the exciting coils 17A and 17C are supplied with a predetermined current to generate a magnetic attraction force between the yoke 14 and the magnetic field. The movement of the bar member 13 fixed to the vibration isolation base floor plate 1 is controlled. Further, the slew rate of the power amplifiers 33a and 33c is increased, and the characteristics of the power amplifiers 33a and 33c are improved so that a current proportional to the input voltage of the power amplifiers 33a and 33c flows in the exciting coils 17A and 17C. Resistors 34a and 34c for detecting a current are connected between the coils 17A and 17C and the ground, and signals from the resistors 34a and 34c are fed back to the inputs of the power amplifiers 33a and 33c.

In the control device having the configuration shown in FIG. 5, the acceleration sensor 21 detects the acceleration of the bar member 13 fixed to the vibration isolation floor plate 1,
It leads to the compensation circuit 31. The output signal from this compensating circuit 31 is led to the power amplifier 33 of both power supplies, and the two exciting coils 17A and 17C.
At the same time that a predetermined current is supplied to the coil, a DC voltage is supplied from the power amplifier 33e to the exciting coils 17E and 17F for bias magnetic field to generate a bias magnetic field. The exciting coils 17A and 17C flow a current in one coil so as to strengthen the magnetic field and in the other coil so as to weaken the magnetic field. This magnetic field causes the electromagnet stator 16
And magnetic isolation force between the yoke and the yoke 14
It is fixed to and the movement of the rod member 13 is controlled. Power amplifier
In order to increase the slew rate of 33 and improve the characteristics of the power amplifiers 33a and 33c so that a current proportional to the input voltage of the power amplifier 33 flows in the exciting coils 17A and 17C, the exciting coil 17A
And a resistor that senses current between the 17C series circuit and ground 34
Is connected to feed back the signal from the resistor 34 to the input of the power amplifier 33.

Hereinafter, the damping action of the control device having the configuration shown in FIGS. 4 and 5 will be described in detail. First, as shown in FIG. 6, in the vibration isolation table floor plate 1 supported on the vibration isolation table installation floor 2 by the air springs 3 and 4, when the vibration isolation table installation floor 2 vibrates at the fluctuating acceleration a ₁ , Consider the vibration acceleration a ₂ of the shaking table floor plate 1. Assuming that the mass of the vibration isolation base plate 1 is M ₀ , the spring constant of the air springs 3 and 4 is K ₀ , and the damping coefficient is C ₀ , this system becomes as shown in FIG. If the natural frequency of this system is set to Ω ₀ , the gain of the transfer function of a ₂ / a ₁ is as shown in Fig. 8, and there is no damping effect in the frequency region where the natural frequency is Ω ₀ or less. . In particular, the gain becomes larger than 1 near the natural frequency Ω ₀ . A vibration system of the vibration isolation base plate 1 is shown in a block diagram as shown in 1 of FIG. In order to achieve the damping effect of the vibration isolation base plate 1, the controller shown in II of FIG. Here, the feedback gains α ₁ , α ₂ , and α ₃ are set to 10 or more. The gain of the transfer function of the system a ₂ / a _{1 obtained} by adding II to the controlled object I is as shown in FIG. In the figure, since the feedback gain α ₁ is selected to be approximately 10, the gain of the transfer function of a ₂ / a ₁ becomes −20 dB at frequencies below the natural frequency Ω ₀ , and the damping effect becomes remarkable. The natural frequency Ω ₀ of this system is Therefore, the vibration isolation base floor plate 1 can be attached to the air springs 3, 4
It can be made smaller than the natural frequency when it is supported by only, and the damping effect is increased.

In the structure of the vibration damping device for the vibration isolation table shown in FIG. 1, the vibration system of the vibration isolation floor plate 1 supported by the air springs 3 and 4 is shown in a block diagram, as shown in I of FIG. Therefore, the control of the magnetic attraction force acting between the yoke 14 of the rod member 13 and the exciting coil 17 and between the yoke flat plate 15 and the electromagnet stators 19a, 19b should be the control system II in FIG. As a result, the natural frequency can be made smaller than that when it is supported by the air springs 3 and 4, and the damping effect is increased. That is, the compensation circuit of FIGS. 4 and 5
By making the characteristics of 31 as shown in block II of FIG. 10, the vibration damping effect becomes large.

In the embodiment described above, the air spring mounting member 11 of the vibration isolation floor plate 1 is provided with a yoke bar having the bar member 13 and the yoke 14, a yoke flat plate 15 is provided at the tip of the yoke bar, and the exciting coil 17 is provided.
The electromagnet stators 19a and 19b are provided in the casing 18 fixed to the air spring attachment member 12 of the vibration isolation table installation floor 2, but the present invention is not limited to this, and the rod member 13 and the yoke 14 are not limited thereto. The yoke bar that is provided is provided on the air spring mounting member 12 of the vibration isolation floor plate 2, and the yoke flat plate 15 is provided at the tip of the yoke rod, and the exciting coil 17 and the electromagnet stators 19a and 19b are the air springs of the vibration isolation floor plate 1. It may be provided on the attachment member 11.

Further, in the above-mentioned embodiment, the structure in which the vibration isolator by the magnetic attraction force of the above-mentioned configuration is provided in the pressure chamber of the air springs 3 and 4,
Of course, the present invention is not limited to this and may be provided outside the pressure chamber.

Further, the vibration isolator having the spring action for suspending the vibration isolation base floor plate 1 and blocking the slight vibration from the vibration isolation base installation floor 2 is not limited to the air spring, and, for example, a vibration isolation rubber is used. It may be one.

〔The invention's effect〕

As described above, according to the present invention, the magnetic attraction type vibration damping control device is provided in parallel with the vibration damping device having the spring action such as the vibration damping rubber or the air spring. Since the vibration isolating action can be improved even at the frequency of, and the vibration isolating action in the horizontal direction is also improved, an excellent effect that a vibration isolating table having a high vibration isolating effect can be realized can be obtained.

Further, by realizing the anti-vibration table having the above high anti-vibration effect, the excellent effect of being able to improve the problem of adversely affecting the product yield and the measurement and observation accuracy due to the vibration from the installation floor such as the semiconductor manufacturing apparatus and the electron microscope. can get.

[Brief description of drawings]

FIG. 1 is a view showing the structure of a vibration damping device for a vibration isolation table according to the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG.
FIG. 4 is a block diagram showing the configuration of the control device when a single power source is used as the power source of the power amplifier, and FIG. 5 is a case where both power sources are used as the power source of the power amplifier. 6 is a block diagram showing the configuration of the control device of FIG. 6, FIG. 6 is a view showing a vibration isolation table using an air spring as a vibration isolation device, FIG. 7 is a one-degree-of-freedom model diagram of FIG. 6, and FIG. FIG. 10 is a diagram showing a gain characteristic of a transfer function of the shaking table, FIG. 9 is a diagram showing a gain characteristic of the transfer function when the feedback gain α _{1 is set} to about 10 in the vibration damping device for a vibration isolation table of the present invention, FIG. FIG. 1 is a block diagram of a vibration isolation table using the vibration isolation device for a vibration isolation table of the present invention. In the figure, 1 ... Vibration isolation table floor plate, 2 ... Vibration isolation table installation floor, 3, 4 ...
… Air springs, 11 …… Air spring mounting members on the floor plate of the vibration isolation table, 12 …… Air spring mounting members on the floor of the vibration isolation table, 13…
… Rod member, 14 …… Yoke, 15 …… Yoke flat plate, 16 …… Electromagnet stator, 17,17A, 17B, 17C, 17D …… Excitation coil, 18 …… Casing, 19a, 19b …… Electromagnet fixed Child, 20a, 20b ... Excitation coil, 21, 21A, 21B ... Acceleration sensor, 22 ... Acceleration sensor, 31 ... Compensation circuit, 32a, 32c ... Linear detection circuit, 33
a, 33c, 33e ... Power amplifier, 34, 34a, 34c ... Resistor.

Claims (4)

[Claims] 1. A vibration isolator having a spring action for suspending a vibration isolation base floor plate to block minute vibrations from a floor on which the vibration isolation base is installed. A yoke bar made of a magnetic material is attached to any one of the shaking table installation floors toward the vibration isolation table installation floor or the vibration isolation table floor plate, and a magnetic material yoke plate is attached to the tip of the yoke bar. A space is provided from the yoke plate to fix it to a member on the vibration isolation table floor plate and the vibration isolation table where the yoke rod is not attached and generate a magnetomotive force in a direction orthogonal to the yoke rod and yoke plate. A fixed electromagnet having an exciting coil for activating the vibration damping base, and an acceleration sensor for detecting the acceleration of the vibration isolation base floor plate, and the yoke bar and the yoke plate and the fixed electromagnet so that the output from the acceleration sensor is constant. Compensation circuit for controlling the magnetic attraction force acting between A vibration damping device for a vibration isolation table, comprising a vibration damping control device including a control device having a force amplifier. 2. An anti-vibration device using an air spring for suspending a vibration isolation base floor plate to shut off minute vibrations from the floor of the vibration isolation base, wherein the air of the vibration isolation base floor plate is placed in a pressure chamber of the air spring. A yoke bar made of a magnetic material is attached to either the spring mounting member or the air spring mounting member on the floor for installing the vibration isolation table, or the air spring mounting member on the floor for installing the vibration isolation table or the air spring mounting member for the floor plate of the vibration isolation table. Along with this, a yoke plate made of a magnetic material is attached to the tip of the yoke bar, a gap is provided from the yoke bar and the yoke plate, and an air spring mounting member of the vibration isolation table floor plate and air of the vibration isolation table installation floor. A fixed electromagnet, which is fixed to a member of the spring attachment member to which the yoke bar is not attached, and which has a coil that generates a magnetomotive force in a direction orthogonal to the yoke bar and the yoke plate, and the acceleration of the vibration isolation floor plate. To detect A control device including a speed sensor, a compensating circuit for controlling a magnetic attraction force acting between the yoke bar and the yoke plate and the fixed electromagnet so that the output from the acceleration sensor is constant, and a power amplifier. A vibration damping device for a vibration isolation table, comprising a vibration damping control device provided. 3. A compensation circuit of the control device, wherein α ₁ × is applied to each of acceleration, velocity and displacement of the vibration isolation floor plate.
M ₀ (M ₀ is the mass of the anti-vibration base floor plate per vibration isolator), α
Feedback coefficient of the control circuit that feeds back the sum of the values obtained by multiplying ₂ × C ₀ (C ₀ is the damping coefficient of the vibration isolator) and α ₃ × K ₀ (K ₀ is the spring constant of the vibration isolator) as the magnetic attraction force. α
_The vibration damping device for a vibration isolation table according to claim 1 or ₂ , wherein ₁ , ₁ , ₂ and α ₃ are set to 10 or more. 4. A compensation circuit of the control device, wherein a resistor for detecting a current of the exciting coil is connected between the exciting coil and ground, and a signal from the resistor is fed back to an input of a power amplifier. The vibration damping device for a vibration isolation table according to claim 1, characterized in that: