JP2851297B2 - Precision vibration isolation device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision vibration isolator, and more particularly to a precision vibration isolator that reduces leakage magnetic flux from a linear motor that is an active brake.

[Prior Art] In precision equipment such as an electron microscope and a holographic apparatus to which an electron beam is applied, vibrations cause an optical path obstruction. In addition, LSI manufacturing equipment such as a stepper repeatedly draws circuits one after another in the same place, but it is not possible to align due to vibration,
It takes a long processing time. For this reason, these precision instruments have conventionally been used mounted on a vibration isolator.
As a vibration isolator, there is a passive vibration isolator that attenuates vibration by a vibration absorbing unit such as an air spring, a coil spring, and a vibration-proof rubber. However, there is such a passive vibration isolator. But,
Even if such a passive vibration isolator can attenuate vibrations from the floor, it cannot be said to be effective against self-excitation of precision equipment itself or natural vibration of a vibration isolator surface plate. Therefore, the X axis, Y axis,
Active vibration isolators that detect each motion component in the Z-axis direction, activate an active controller in antiphase corresponding to the motion component in each direction, and actively vibrate the vibration are used. I have. In this active anti-vibration apparatus, as shown in FIG. 6, a platen 20 on which precision equipment 9 is mounted is supported from a gantry 40 fixed to a floor 30 by an air spring 50 as a passive controller, The vibration of the surface plate 20 was detected by the sensor 60 attached to the surface plate 20, and the signal of the sensor 60 was amplified by the preamplifier 70, processed by the control unit 80, amplified by the power amplifier 90, and then generated on the surface plate 20. The active controller 10 is actuated so as to vibrate the vibration in the opposite phase to the vibration, and the vibration is quickly removed. Although FIG. 6 illustrates the vibration isolation of one motion component,
Vibration is removed in at least three directions.

As the active controller 10 of such an active vibration isolator, a hydraulic actuator, an air actuator, an electromagnetic actuator, or the like is used. In particular, a linear motor such as a voice coil motor is used. However, a linear motor such as a voice coil motor has a large leakage magnetic flux. For example, a voice coil motor that generates 10N has a leakage magnetic flux density of about 3 G in an opening. For this reason, there is a method of installing the voice coil motor by covering it with a thick iron plate, etc.
A slight leakage flux is observed. The structure of the voice coil motor is a low-leakage magnetic circuit, and it is possible to keep the leakage magnetic flux density below 1G.However, in order to shield the magnetic flux reliably when stationary, the linear motor is covered with a magnetic shielding member. A vibration isolator has been proposed by the present applicant (Japanese Patent Application No. 1-9452).

[Problems to be Solved by the Invention] However, these conventional methods for controlling the leakage magnetic flux are the leakage magnetic flux control in a stationary state, and cannot control the leakage magnetic flux in a fluctuating state caused by the operation of a linear motor or the like. If an electron microscope or a holographic device using an electron beam is mounted in the occurrence of such a leakage magnetic flux, the performance thereof is impaired. Therefore, there is a need for a leakage magnetic flux control that actively reduces the leakage magnetic flux due to the fluctuating magnetic field to almost zero so as not to impair the performance of precision equipment mounted and used on the precision vibration isolation device.

[Object of the Invention] The present invention has been made in order to solve the above problems, and detects the fluctuating magnetic field components in each of the X-axis, Y-axis, and Z-axis directions of the surface plate, and makes the leakage magnetic flux almost zero. Activate the degaussing coil in antiphase according to the fluctuating magnetic field component,
It is an object of the present invention to provide a precision anti-vibration device that actively controls.

Means for Solving the Problems In order to achieve the above object, a precision vibration isolator according to the present invention is an active brake element that is activated by an output signal of a sensor that detects vibration of a surface plate on which precision equipment is mounted. A precision vibration isolator equipped with a certain linear motor, the X-axis and Y-axis of a surface plate generated by the operation of the linear motor.
And a detection control unit comprising a Hall element for detecting and processing the leakage magnetic flux in each of the fluctuating magnetic field components in the respective directions of the axis and the Z axis, and a detection controller from the detection control unit covering the directions of the X, Y and Z axes of the surface plate. A demagnetizing coil is provided which operates in an opposite phase in response to a fluctuating magnetic field component by a control signal and actively performs feedback control so as to make leakage magnetic flux substantially zero.

[Embodiment] Hereinafter, a preferred embodiment of a precision vibration isolator according to the present invention will be described in detail with reference to the drawings.

The precision anti-vibration apparatus according to the present invention includes a linear motor 10 (FIG. 6) which is an active brake element that is activated by an output signal of a sensor 60 for detecting vibration of the surface plate 20.

In this precision anti-vibration device, as shown in FIG.
Is composed of a search coil 3, an amplifier 40a for amplifying a signal detected by the search coil 3, and an integrator 4 for performing arithmetic processing. Another amplifier 5 is provided between the degaussing coil 1 that covers the directions of the X, Y, and Z axes of the surface plate 20 and the detection control unit 2.

Alternatively, it is preferable to use a Hall element 6 as the detection control unit 2 as shown in FIG.

In order to actively control the Z-axis component of the surface plate 20 of the leakage magnetic flux due to the fluctuating magnetic field, a demagnetizing coil 1z surrounding the side surface of the surface plate 20 is provided as shown in FIG. Similarly, to actively control the X-axis component of the surface plate 20 in the leakage magnetic flux due to the fluctuating magnetic field, as shown in FIG. The demagnetizing coils 1x surrounding the upper and lower side surfaces of the surface plate 20 are provided on both sides of the surface plate so as to actively control the power supply. To actively control the Y-axis component of the surface plate 20, a degaussing coil 1y orthogonal to the degaussing coil 1x for actively controlling the X-axis component is provided on both sides of the surface plate 20 (not shown).
It is preferable that these degaussing coils 1x, 1y, 1z be provided inside the surface plate 20.

[Operation] In the precision vibration isolator configured as described above, the leakage magnetic flux in the fluctuation state caused by the operation of the linear motor 10 (see FIG. 6) as the active brake is detected by the search coil 3 of the detection control unit 2. The signal detected by the search coil 3 is amplified by the amplifier 40a, and is processed by the integrator 4. The signal sent from the detection control unit 2 is amplified by another amplifier 5, and the control signal of each axis, which has been similarly detected, demagnetizes the X, Y, and Z axes of the surface plate 20. When the coil 1 is operated, the platen 20 is feedback-controlled.

Alternatively, when the Hall element 6 is used as the detection control unit 2 as shown in FIG. 3, the leakage magnetic flux is detected and calculated by the Hall element 6, and the detection control unit 2 is operated in the same manner as described above.
The signal sent from the amplifier is amplified by another amplifier 5, and the control signal of each axis, which has been similarly detected, is used to control the X of the surface plate 20.
Since the demagnetizing coil 1 that covers the directions of the axis, the Y axis, and the Z axis is operated, the platen 20 is feedback-controlled.
The operation of the degaussing coil 1 is controlled by increasing or decreasing the current by the signal amplified by the amplifier 5. After the leakage magnetic flux generated by the operation of the linear motor 10 is detected and processed,
The demagnetizing coils 1x, 1y, and 1z provided so as to cover the directions of the X, Y, and Z axes respectively operate in opposite phases as shown in FIG. To almost zero.

Among the above, in the method using the Hall element 6, unlike the search coil 3, the strength of the magnetic field H (t) itself is measured, so that the leakage magnetic flux due to the fluctuating magnetic field is actively reduced to almost zero by only the proportional control. However, if the above-described integration circuit is further added, it can be completely reduced to zero.

The DC magnetic field can be controlled by passing a constant current through the degaussing coil.

[Effects of the Invention] As is clear from the above embodiments, according to the precision vibration isolator of the present invention, the X-axis and the Y-axis of the leakage magnetic flux due to the fluctuating magnetic field.
The degaussing coil can be operated in an opposite phase corresponding to each component of the fluctuating magnetic field to make the components of the axis and the Z axis substantially zero, and can be actively controlled.

[Brief description of the drawings]

FIGS. 1, 2 and 3 are explanatory views of the leakage magnetic flux control by a degaussing coil provided on the surface plate of the precision vibration isolator according to the present invention, and FIG. 4 is a surface plate of the precision vibration isolator according to the present invention. Z provided for
FIG. 5 is a diagram showing a degaussing coil for controlling the axial direction, FIG. 5 is a diagram showing a degaussing coil for controlling the X-axis direction provided on the surface plate, and FIG. 6 is a schematic configuration diagram of a conventional active vibration isolator. 1, 1x, 1y, 1z ... degaussing coil 2 ... detection control unit 6 ... Hall element 9 ... precision equipment 10 ... linear motor as active braking element 20 ... surface plate 60 ... sensor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Keiichi Takayama 2-1-1, Sakae Oda, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Showa Electric Wire & Cable Co., Ltd. (56) References JP-A-62-114011 (JP, A ) Jpn. Sho 57-202292 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G05D 19/02

Claims (1)

(57) [Claims] 1. A precision anti-vibration apparatus having a linear motor (10) which is an active brake actuated by an output signal of a sensor (60) for detecting vibration of a surface plate (20) on which a precision instrument (9) is mounted. X of the surface plate generated by the operation of the linear motor
A detection control unit (2) including a Hall element (6) for detecting and processing a leakage magnetic flux in a fluctuating magnetic field component in each of the axis, Y-axis, and Z-axis directions; A degaussing coil (1, 1) that operates in the opposite phase corresponding to the fluctuating magnetic field component and actively feedback-controls the leakage magnetic flux to substantially zero according to a control signal from the detection control unit while covering a direction.
x, 1y, 1z).