JP5102089B2 - Gas pressure control type micro vibration control device - Google Patents

Description

  The present invention relates to a gas pressure control type microvibration control device, and more particularly to a gas pressure control type microvibration control device that microvibrates a support object by controlling the gas pressure.

  Actuators that use fluid pressure are well known, as represented by piston and cylinder mechanisms. The fluid pressure actuator can drive a moving body by controlling the fluid pressure using a fluid pressure servomechanism. In particular, a gas pressure control actuator that uses a gas such as air is expected to be an easy-to-handle positioning device because it has less contamination problems than an oil pressure control actuator.

  Patent Document 1 focuses on the high spring constant of the gas bearing mechanism, changes the gap of the gas bearing by controlling the gas pressure supplied thereto, and uses this change in the gap for minute movement of the object. A configuration that realizes a fine movement mechanism with good characteristics is shown. Here, there is a guide portion that guides the mover to which an appropriate pressing force is applied in the moving direction, and control is performed from the opening provided in the gas receiving wall that is the bottom surface of the guide portion toward the gas receiving surface of the mover. The gas having the gas pressure is supplied, the mover floats from the gas receiving wall, forms a gap while balancing with the pressing force, and the mover is moved slightly by controlling the amount of the gap by the supply gas pressure. The In addition, it is also stated that by arranging a plurality of movers in the axial direction and supplying a controlled gas pressure to the gaps between adjacent movers, the range of minute movement can be expanded according to the number of gaps. It has been.

  By developing the configuration disclosed in Patent Document 1, a plurality of thin movers are arranged in the axial direction, and a controlled gas pressure is supplied to the gap between adjacent movers. The gas pressure control actuator which is small as a whole and has a wide movement range of minute movement can be configured.

JP 2005-268293 A

  As described above, in Patent Document 1, by utilizing the high spring constant of the gas bearing mechanism, it is possible to control the amount of gap through which the gas flows by balancing the pressing force with the gas pressure. If acceleration is generated by changing the gap amount, it is likely that minute vibrations can be controlled by gas pressure. If a minute vibration can be controlled, it may be widely used for a vibration isolator or the like.

  However, if the spring constant of the gas gap, that is, the gas bearing rigidity related to the change in the gap amount with respect to the change in the gas pressure is high, the damping characteristic of the gas gap is also high accordingly. The acceleration that is the time derivative cannot be controlled with high accuracy.

  That is, with the configuration of Patent Document 1, it is impossible to accurately control the acceleration or thrust, which is the second-order time differential amount of the gas gap amount.

  An object of the present invention is to provide a gas pressure control type microvibration control device capable of microvibrating a support object by gas pressure control.

Gas pressure control type micro vibration control apparatus according to the present invention, the gas blowout part possess the objective top surface facing the supporting object, an objective pad flowing gas to the objective gap between the objective top and the supporting object, the gas has a through window that can flow, alignment in which a plurality of flat plate-friendly Doko arranged aligned parallel to the opposite side of the pad back side and the objective upper surface of the objective pads are the aligned multiple flat armature a casing for movably accommodated in the axial direction, and a gas outlet portion of the objective pad, a through window of each flat plate armature, advanced side flat plate facing the pad back surface of the plurality of flat plate-friendly Doko and the pad-side gap is a gap between the movable element and the pad back surface, the gap between the movable element which is a gap between the adjacent flat plate-friendly Doko, the bottom surface of the housing portion of the plurality of flat plate-friendly Doko The bottom side, which is the gap between the flat plate mover at the rear end facing to the bottom of the housing The gap control gas supply means for supplying a gap control gas and between, with the objective pad, a a stop surface extending toward the outer circumferential side from the gas blowout part, the amount of change in the objective gap to gas pressure changes The gas bearing stiffness characteristic has a predetermined value that can control the objective gap amount, and each flat plate mover has a positive sign in the gas bearing stiffness characteristic related to the change amount of each mover gap with respect to the gas pressure change. Each having a gas restrictor set to 1/10 or less of a predetermined value of the gas bearing rigidity characteristic in the objective pad, controlling the gas pressure of the gap control gas, and pressing force from the support object The object to be supported is minutely vibrated while adjusting the interval of each gap while balancing.

  Further, in the gas pressure control type micro vibration control device according to the present invention, the objective pad has a gas discharge part for discharging the gas flowing out from the gas blowing part and flowing through the gap between the support object and the object upper surface. The casing portion has an outer peripheral space provided along the axial direction on the outer peripheral side of the plurality of flat plate movers, and the gas discharge portion is connected to an external exhaust device via the outer peripheral space. It is preferred that

  Moreover, in the gas pressure control type micro vibration control device according to the present invention, the housing part has an outer peripheral side space provided along the axial direction on the outer peripheral side of the plurality of flat plate movers, and the outer peripheral side space. It is preferable to provide a bias gas supply means for supplying a gas having a predetermined gas pressure to the support object and applying a predetermined bias support force to the support object.

  Further, in the gas pressure control type micro vibration control device according to the present invention, it is preferable that a support object or an objective pad and a housing part are connected in an airtight manner and a bellophram made of rubber or plastic rubber is provided.

Further, in the gas pressure control type micro vibration control device according to the present invention, the objective pad has a plurality of narrow grooves extending from the gas blowing portion toward the outer peripheral side as the surface diaphragm, and each flat plate movable element is a gas diaphragm. As a part, it is a plurality of grooves extending from the through window toward the outer peripheral side, and it is preferable that the groove width is wider and the groove depth is deeper than the narrow groove of the objective pad .

  Further, in the gas pressure control type micro vibration control device according to the present invention, the center support shaft is provided inside the housing portion and supports the center portion of each flat plate movable element, and the displacement rigidity in the alignment axis direction. It is preferable to provide a central support shaft that supports the support member via a support member that is smaller than the displacement rigidity in the radial direction.

  Further, the gas pressure control type micro vibration control device according to the present invention includes a control unit that acquires the acceleration of the object to be supported or the objective pad and controls the gas pressure of the gap control gas according to the acquired acceleration. Is preferred.

  In the gas pressure control type micro vibration control device according to the present invention, it is preferable that a plurality of objective pads are provided on the support object so as to support the support object in the directions of three orthogonal axes.

  With the above configuration, the gas pressure control type micro vibration control device has a plurality of flat plate-like movable elements having a through window through which gas can flow and arranged in parallel on the back surface of the object pad opposite to the object upper surface. The gap control gas is supplied to the gaps between the movers and the like. The configuration up to this point is the same as the minute clearance control using the gas bearing in Patent Document 1 described above. What differs from the content in Patent Document 1 is a gas restrictor provided in each flat plate movable element. Here, each flat plate mover has a gas constriction part in which the gas bearing rigidity characteristic relating to the change amount of each mover gap with respect to the change in gas pressure has a positive sign and is set to a predetermined threshold rigidity value or less. .

  If the gas restrictor such as the surface restrictor is eliminated and each flat plate movable element has a flat surface, the gas bearing rigidity characteristics between the flat plate movable elements are minimized. However, according to experiments, if a gas restricting part such as a surface restrictor is eliminated, even if an attempt is made to flow gas into the gap between adjacent flat plate movers, the gap may be zero or stick to each other. In other words, if the gas restrictor such as the surface restrictor is eliminated, the gas bearing stiffness characteristic related to the change amount of each mover gap with respect to the change in gas pressure may be negative. In this state, the acceleration that is the second-order time differential amount of the gap amount cannot be controlled by the gas pressure.

According to the above configuration, each flat plate mover is provided with a gas restrictor, but the gas bearing stiffness characteristic related to the amount of change in each mover gap with respect to the change in gas pressure has a positive sign, and is provided on the objective pad. The gas bearing rigidity characteristic is set to 1/10 or less of the gas bearing rigidity characteristic of the surface diaphragm. For example, one example of the gas bearing stiffness characteristic described in Patent Document 1 is about (gap change amount / gas pressure change amount) = (5 μm / 0.1 MPa) . When the gas bearing rigidity characteristic is set to this value, the gas bearing rigidity characteristic of each flat plate movable element is set to 10% (0.5 μm / 0.1 MPa) or less .

  In this way, by setting the gas bearing rigidity characteristic of the gas constriction part as low as about 1/10, the attenuation characteristic of the gap through which the gas flows can be reduced accordingly, and the second level of the gap amount by the gas pressure. It is possible to control the acceleration that is the time derivative. Thereby, the support target object on the objective pad can be minutely vibrated by the gas pressure control.

  In the gas pressure control type micro vibration control device, the objective pad has a gas discharge portion that collects the gas blown from the gas blow-out portion, and the housing portion has a shaft on the outer peripheral side of the plurality of flat plate movers. An outer peripheral side space provided along the direction is provided, and the gas discharge unit is connected to an external exhaust device via the outer peripheral side space. It is possible to efficiently recover the gas used for blowing out from the gas blowing section and floating the support object.

  Further, in the gas pressure control type micro vibration control device, the casing portion has an outer peripheral side space provided along the axial direction on the outer peripheral side of the plurality of flat plate movers, and is predetermined in the outer peripheral side space. Bias gas supply means for supplying a gas having a predetermined gas pressure and applying a predetermined bias support force to the support object via the objective pad is provided. As a result, for example, a bias support force having a constant value can be generated while generating a small acceleration by the gap control gas.

  In addition, in the gas pressure control type micro vibration control device, the objective pad and the casing are connected in an airtight manner and a bellophram made of rubber or plastic rubber is provided. Even when the pad moves in a plane parallel to the objective upper surface, for example, a bias supporting force having a constant value can be generated while generating a minute acceleration by the gap control gas.

  Further, in the gas pressure control type micro vibration control device, the objective pad has a surface stop provided on the upper surface of the objective and extending from the gas blowing portion toward the outer peripheral side. In this case, it is preferable that the surface diaphragm control the gap amount with high accuracy by taking the gas bearing rigidity characteristics sufficiently high. Thereby, the support object can be controlled to be levitated with high accuracy with respect to the upper surface of the objective pad with respect to the objective.

  Further, in the gas pressure control type micro vibration control device, the center support shaft is provided inside the casing and supports the center of each flat plate mover, and the displacement rigidity in the alignment axis direction is in the radial direction. And a center support shaft that supports the support member through a support member smaller than the displacement rigidity. Thereby, when each flat plate movable element vibrates along the central axis, it is possible to suppress each flat plate movable element from shifting in the radial direction of the central axis.

  Further, in the gas pressure control type micro vibration control device, the acceleration of the support object is acquired, and the gas pressure of the gap control gas is controlled according to the acquired acceleration. Can be made.

  Further, in the gas pressure control type micro vibration control device, a plurality of objective pads are provided for the support object so as to support the support object in the directions of three orthogonal axes. For example, the vibration can be eliminated by canceling out the three-dimensional vibration of the support object.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, a vibration isolation table will be described as an object to be supported by the gas pressure control type micro vibration control device, but the support object may be other than this. For example, it may be a platform for removing vibrations or a device such as a measuring instrument for removing vibrations.

  In addition, as a method of supporting the support object, the support object is supported in three orthogonal directions of XYZ, and the gas pressure control type micro vibration control having an objective pad that supports the support object in the Z direction. Three types of gas pressure control type micro vibration control device, gas pressure control type micro vibration control device having an objective pad supported in the X direction, and gas pressure control type micro vibration control device having an objective pad supported in the Y direction Although an example in which a control device is provided will be described, of course, the support object may be supported only in one direction, or may be supported in two orthogonal directions.

  Further, although the description will be made assuming that the support object is not directly supported by the objective pad but is attached to the movable base supported by the objective pad, other attachment methods and support methods may be used. For example, when the support object is supported only in one direction of the Z direction, the support object may be directly supported by the objective pad so as to be levitated. In addition, the dimensions, materials, numbers, and the like described below are examples for explanation, and other conditions can be used depending on the purpose of use.

  FIG. 1 is a diagram showing a configuration of a vibration isolation system 200 in which a gas pressure control type micro vibration control device 100 is used. Hereinafter, the gas pressure control type micro vibration control device is simply referred to as a micro vibration control device. In the vibration isolation system 200, the vibration of the vibration isolation table 202 is detected by the acceleration detector 204, the gas pressure is controlled by the control unit 206 according to the detected acceleration, and the controlled gas pressure is controlled by the micro vibration control device 200. System that has a function of canceling vibrations by canceling minute vibrations of the vibration isolation table 202 attached to the movable table via the mounting portion 210 by causing the movable table, which will be described later, to minutely vibrate by the minute vibration control device 200. It is.

  In the example of FIG. 1, the vibration isolation table 202 is attached to the movable table at a plurality of attachment portions 210 at the bottom. For example, in the case of the vibration isolation table 202 having a rectangular planar shape, four minute vibration control devices 100 are arranged at each corner of the rectangle, and the mounting portions are attached to the four movable stands supported by the respective minute vibration control devices 100. The vibration isolation table 202 can be attached via 210. In the case of the vibration isolation table 202 having a circular planar shape, a plurality of minute vibration control devices 100 are arranged evenly along the outer circumference of the circle and attached to each movable table supported by each minute vibration control device 100. The vibration isolation table 202 can be attached via the unit 210.

  2 and 3 are diagrams showing a configuration of the minute vibration control device 100, FIG. 2 is a top view, and FIG. 3 is a front sectional view. FIGS. 1 to 3 show the X direction, the Y direction, and the Z direction, which are directions of three orthogonal axes. Here, the XY plane is a plane parallel to the upper surface of the vibration isolation table 202, and the Z direction is a direction perpendicular to the XY plane. FIG. 1 is a diagram viewed from the XZ plane, FIG. 2 is a diagram viewed from the XY plane, and FIG. 3 is a diagram viewed from the XZ plane.

  The micro-vibration control device 100 includes, for example, a casing 102 that is fixed to the base portion of the vibration isolation system 200, a movable base 104 to which the mounting portion 210 of the vibration isolation base 202 described in FIG. Are supported by the five gas pressure support mechanisms 12, 14, 16, 18, 20 and the gas pressure support mechanisms 12, 14, 16, 18, 20, respectively. It comprises gas pressure control valves 13, 15, 17, 19, 60 to be connected.

  2 and 3, the casing 102 is a case body having a rectangular planar shape, and accommodates the movable base 104 and the five gas pressure support mechanisms 12, 14, 16, 18, and 20. As described above, the casing 102 is fixed to the base of the vibration isolation system 200 by appropriate fixing means.

  The movable table 104 has a flange portion on the bottom surface side, a prismatic portion on the upper portion of the flange portion, and is levitated via gas by the five gas pressure support mechanisms 12, 14, 16, 18, and 20, and is XYZ. The table is supported so as to be movable in the three-axis direction. As shown in FIG. 2, the prismatic part of the movable base 104 is a rectangular shape in which the planar shape is appropriately rounded at the corners, and the four sides of the rectangular shape are two sides parallel to the X direction and the Y direction. Are two sides parallel to. These sides respectively extend in the Z direction to form an XZ plane or a YZ plane. The bottom surface of the movable table 104 is a surface parallel to the XY plane. Further, the upper surface of the movable table 104 is a surface to which the mounting part 210 of the vibration isolation table 202 is attached.

  The five gas pressure support mechanisms 12, 14, 16, 18, and 20 can be classified into three types. The gas pressure support mechanisms 12 and 14 face the YZ plane of the movable table 104 and have a function of giving the movable table 104 minute vibrations in the X direction. The gas pressure support mechanisms 16 and 18 face the XZ plane of the movable table 104 and have a function of applying minute vibrations in the Y direction to the movable table 104. When the YZ plane and the XZ plane of the movable base 104 have substantially the same area, the gas pressure support mechanisms 12, 14, 16, and 18 have the same configuration except for the positions arranged in the housing. Can be used.

  The other gas pressure support mechanism 20 faces the XY plane on the bottom surface of the movable table 104 and has a function of giving the movable table 104 minute vibrations in the Z direction. The gas pressure support mechanism 20 supports the weight of the vibration isolation table 202 described with reference to FIG. 1, and further applies minute vibrations in the Z direction to the vibration isolation table 202. Therefore, the gas pressure support mechanisms 12, 14, 16 , 18 and larger. Accordingly, in order to increase the area of the bottom of the movable table 104 on the XY plane, the movable table 104 is provided with the above-described lung portion.

  The five gas pressure control valves 13, 15, 17, 19, 60 are gas controlled by the five gas pressure support mechanisms 12, 14, 16, 18, 20 under the control of the control unit 206 described in FIG. It is a control valve that supplies pressure. As described above, the gas pressure control mechanism 12, 14, 16, 18 and the gas pressure support mechanism 20 are different in size, and compared with the gas pressure control valves 13, 15, 17, 19, the gas pressure control valve 60 has a large gas flow capacity. As the gas pressure control valves 13, 15, 17, 19, 60, actuator-driven control valves that control the output gas pressure by driving the actuator with an electric signal can be used. For example, a force motor drive spool / sleeve type gas pressure control valve or the like can be used.

  As described above, the gas pressure support mechanisms 12, 14, 16, 18, and 20 are different only in size and the like, and the basic configuration can be the same. The configuration will be described. In FIG. 3, a configuration including the gas pressure support mechanism 20 and the gas pressure control valve 60 used therefor is shown as the Z-direction microvibration unit 10.

  FIG. 4 is a top view of the gas pressure support mechanism 20, and FIG. 5 is a diagram illustrating the configuration of the Z-direction microvibration unit 10 including the gas pressure support mechanism 20 and the gas pressure control valve 60. FIG. 6 is a view showing the central shaft 32 constituting the gas pressure support mechanism 20, and FIG. 7 is a view showing the flat plate movable element 50.

  The gas pressure support mechanism 20 includes a housing portion 21 having an objective pad 22, a housing body 26, and a telescopic wall portion 24 that hermetically connects the objective pad 22 and the housing body 26. Inside the housing portion 21 are housed a central axis 32 and a plurality of flat plate movable elements 50 arranged around the central axis 32 in the axial direction.

  The objective pad 22 is a flat plate-like member for supporting the movable table 104 that is a support object in a non-contact manner, and the upper surface thereof is the objective upper surface 23 that faces the movable table 104. The objective upper surface 23 is processed into a flat surface so that gas flows smoothly on the surface. Moreover, the objective pad 22 is connected to the telescopic wall part 24 in the outer peripheral part of the back surface side. The objective pad 22 may be a disc formed using a suitable metal material. In some cases, a ceramic material or a plastic material can be used. Appropriate surface treatment can be performed on the surface of the objective pad 22.

  The gas outlet 30 provided in the center of the objective upper surface 23 is an air outlet connected to the gas pressure control valve 60, and is an opening for supplying a gap control gas that flows in the gap between the objective upper surface 23 and the movable table 104. Part.

  Further, on the objective upper surface 23, the gas discharge groove 44 disposed in an annular shape outside the gas outlet 30 is a gas discharge portion connected to the exhaust device 45 via the exhaust port 48 (see FIG. 5). This is a discharge groove for collecting the gap control gas supplied from the gas outlet 30.

  A gas suction groove 46 provided in an annular shape on the outer peripheral side of the gas discharge groove 44 on the objective upper surface 23 is a gas suction portion connected to the pressure reducing source 47 and sucks the gas leaking from the gas discharge groove 44. It is a decompression groove for doing. The gas suction groove 46 passes through a pipe line provided inside the objective pad 22 and is connected to an external decompression source 47 through a connection port provided in the outer peripheral portion of the objective pad 22. By providing the gas suction groove 46, the gas pressure support mechanism 20 can be operated in a vacuum environment, for example.

  In the objective upper surface 23 that is the upper surface of the objective pad 22, a plurality of narrow grooves 42 that are shallow and narrow grooves extending radially from the center are provided between the gas outlet 30 and the gas discharge groove 44. The narrow grooves 42 extending radially form a recess 40 that is shared on the inner diameter side of the disk. That is, on the upper surface of the objective pad 22, the inner diameter side portion has a thickness of a portion with a predetermined radius from the center of the gas outlet 30 to form a recess 40, and the recess 40 is a starting point of each narrow groove 42. From this point, the narrow groove 42 extends in the radial direction by a predetermined length. The distal end portion of the narrow groove 42 extending in the radial direction spreads on both sides in the circumferential direction there, and stops its expansion to the extent that it does not connect with the circumferential spread of the adjacent narrow groove 42. The shape of the recess 40 and the narrow groove 42 is an example of a surface stop, and may be a surface stop having another appropriate shape.

  In this way, the recess 40 and the narrow groove 42 are provided so as to exert a throttling effect when gas flows in the radial direction from the gas outlet 30 on the objective upper surface 23. That is, gas flows in the gap between the two surfaces facing the objective upper surface 23 and the lower surface of the movable table 104, and the gas flowing through the recess 40 and the narrow groove 42 overflows on the flat plate surface at the end of the narrow groove 42. Sometimes, the flow path becomes narrower and narrowed, resulting in a so-called surface restriction. The effect of this surface restriction stabilizes the flow between the two surfaces and also stabilizes the distance between the two surfaces.

  The depth of the recess 40 and the narrow groove 42 can be about 10 μm to about 20 μm. If the outer shape of the objective pad 22 is about 30 mm, for example, the radial width of the recess 40 can be about 1 mm to 6 mm, and the width of the narrow groove 42 can be about 0.2 mm to about 2 mm.

  The gas recovered by the exhaust device 45 and the gas recovered from the decompression source 47 can be returned to the gas pressure control valve 60 and the like for reuse.

  The stretchable wall portion 24 is an annular accordion-like stretchable member having a bottom-side connection portion on the outer peripheral portion of the housing body 26 and a top-side connection portion on the outer peripheral portion of the side surface on the back side of the objective pad 22. . The telescopic wall portion 24 is connected to both the housing body 26 and the objective pad 22 with an airtight structure. As the stretchable wall portion 24, a bellows-like member made of a suitable plastic material or rubber material, or a bellows-like member made of a metal thin plate can be used. In some cases, instead of the bellows-like stretchable member, a metal bellows-like stretchable member or a diaphragm-like stretchable member may be used. Alternatively, when a small amount of gas leakage can be allowed, sleeves having different inner diameters may be arranged in the radial direction over several stages, and a structure that sequentially moves in the axial direction to a so-called bamboo slab shape may be used.

  The housing body 26 is a member having a disk-like outer shape having the same outer diameter as that of the objective pad 22, and an annular recess having a central hole is provided at the center thereof. In this annular recess, a central shaft 32 is detachably installed. As described above, an annular elastic wall portion 24 is provided upright on the outer peripheral portion of the housing body 26, thereby forming a container-like space having an upper opening, and a flat plate movable element is formed in this space. 50 is stored.

  As described above, the housing body 26 has a function of accommodating the plurality of flat plate movable elements 50 together with the telescopic wall portion 24. In particular, the flat plate movable elements 50 are arranged around the central axis 32 along the axial direction. It has a function. A gas supply port 38 (see FIG. 5) connected to the gas pressure control valve 60 passes through the bottom surface of the housing body 26 at the center, and is connected to the exhaust device 45 on the outer peripheral side of the bottom surface. An exhaust port 48 (see FIG. 5) is provided.

  The central shaft 32 is in an annular recess formed on the upper surface side of the gas supply port 38 which is a through hole at the center of the housing body 26 and has an outer diameter larger than the inner diameter of the gas supply port 38. It is a shaft arranged upright. FIG. 6 shows the state of the central axis 32. The central shaft 32 has a central through hole at the center thereof, and the outer shape has a hexagonal star ridge shape, and a plurality of communication holes 34 communicating with the central through hole are provided in the starring-shaped valley portion. As described above, since the central shaft 32 is disposed upright in the annular recess on the upper surface side of the gas supply port 38, the central through hole of the central shaft 32 communicates with the gas supply port 38. Therefore, the communication hole 34 provided in the side surface of the central shaft 32 communicates with the gas supply port 38, and the gap control gas supplied from the gas pressure control valve 60 can be blown out. The blown-out gas flows in the radial direction toward each flat plate movable element 50, and in the axial direction, flows upward from the star-shaped valley to the gas outlet 30.

  If necessary, a gap amount sensor can be disposed in the central through hole of the central shaft 32. By arranging the gap amount sensor, the gap between the objective upper surface 23 of the objective pad 22 and the movable base 104 which is a non-contact support object is detected, and the data is transmitted to the control unit 206 described in FIG. However, it can be used to control the gap amount. In that case, the gas supplied from the gas supply port 38 can sufficiently flow into the gas outlet 30 and the communication hole 34 by making the outer shape of the gap amount sensor smaller than the inner diameter of the central through hole. As the gap amount sensor, a capacitive sensor, a magnetic sensor, an optical sensor, or the like can be used.

  Returning again to FIG. 5, the plurality of flat plate movable elements 50 arranged around the central axis 32 has a function of generating a minute displacement for moving the objective pad 22 with respect to the housing body 26 of the housing portion 21. Have. The state of the flat plate movable element 50 is shown in FIG.

  The flat plate movable element 50 is a donut-shaped member having a concentric opening 54 at the center of the disk 52. The opening 54 has an inner diameter large enough to allow the central shaft 32 to be sufficiently disposed therein. Two-stage depressions 56 and 58 are provided on the outer peripheral side of the opening 54. The depressions 56 and 58 are formed when the gap control gas flows out from the opening 54 to the surface of the disk of the flat plate movable element 50 and flows to the outer peripheral side through the gap between the adjacent flat plate movable elements 50, for example. It has a function as a gas throttle part which restrict | squeezes the gas flow. Due to the function of the gas restrictor, rigidity and damping characteristics are imparted to the gas flowing through the gap.

Here, in the case of the surface restriction by the narrow groove 42 described with reference to FIG. 4, the gas bearing rigidity characteristic with respect to the change amount of the gas gap with respect to the change of the gas pressure is considerably large, and thereby the gap amount is accurately controlled by the gas pressure. it can. For example, in the case of the dimensions such as the narrow groove 42 described with reference to FIG. 4, the diameter to the position of the gas discharge groove 44 in the objective pad 22 is about 30 mm to about 300 mm, and the inner diameter of the gas outlet is about 10 mm to 30 mm. and about 10μm nominal standard value of the gap which flows, when about 0.2MPa gas pressure P _S, can be a (clearance variation / gas pressure variation) = (5 [mu] m / 0.1 MPa) degree.

  On the other hand, the gas throttle portion of the flat plate movable element 50 shown in FIG. That is, the gas bearing rigidity characteristic of the throttle portion of the flat plate movable element 50 has a positive sign and is set to a predetermined threshold rigidity value or less. Here, the threshold stiffness value is preferably about 1/10 or less of the gas bearing stiffness characteristics set when the gap amount is accurately controlled in the same gap flow. In the above example, when the diameter of the flat plate mover 50 is about 30 mm to about 300 mm, the inner diameter of the gas outlet is about 10 mm to 30 mm, and the nominal standard value of the gap through which the gas flows is about 10 μm, Amount / gas pressure change amount) = (0.5 μm / 0.1 MPa) or less.

  In this way, by setting the gas bearing rigidity characteristic of the gas throttle portion of the flat plate movable element 50 to be small, the attenuation characteristic of the gap through which the gas flows can be lowered accordingly, and the second level of the gap amount can be reduced by the gas pressure. It is possible to control the acceleration that is the time derivative. As a result, the movable table 104, which is a support object on the objective pad 22, can be minutely vibrated by gas pressure control.

  An example of the dimensions of the flat plate movable element 50 in FIG. 7 is as follows. The outer diameter is about 30 mm to about 300 mm, the inner diameter is about 5 mm to 10 mm, the plate thickness is about 0.05 mm to about 2 mm, and the depth of the depression 56 The depth is about 100 μm to about 300 μm, and the depth of the recess 58 is about 300 μm to about 500 μm. The flat plate movable element 50 can be obtained by processing a metal disk such as SUS.

  In order to set the gas bearing rigidity characteristic small, it is possible to use the surface restriction described with reference to FIG. 4 in addition to the gas restriction part by the two-stage depression in FIG. FIG. 8 is a view showing an example of a flat plate movable element 70 having such a surface stop. The flat plate movable element 70 has an opening 74 at the center of the circular plate 72, and further has a recess 76 and a wide groove 78. That is, a plurality of wide grooves 78 that are deep and wide grooves extending radially from the center are provided on one surface of the flat plate surface of the flat plate movable element 70. The wide groove 78 extending radially is common to the inner diameter side of the disk and forms a deep recess 76. That is, the portion on the inner diameter side of the flat plate movable element 70 has a thickness of a portion with a predetermined radius from the center to form a deep recess 76, and the recess 76 becomes a starting point of each wide groove 78, and from there The wide groove 78 extends in the radial direction with a length of. The distal end portion of the wide groove 78 extending in the radial direction then spreads on both sides in the circumferential direction, and stops its expansion to the extent that it does not connect with the circumferential expansion of the adjacent wide groove 78. The shape of the recess 76 and the wide groove 78 is an example of a surface stop, and may be a surface stop having another appropriate shape. Note that the recess 76 and the wide groove 78 may be provided on both sides of the flat plate movable element 70.

  In this way, the recess 76 and the wide groove 78 are provided so as to exert a throttling effect when gas flows in the radial direction along the surface of the flat plate movable element 70. That is, the flat plate surface of the flat plate movable element 70 faces the other surface, gas flows into the gap between the two surfaces, and the gas flowing through the recess 76 and the wide groove 78 is flat at the end of the wide groove 78 and the like. When the surface overflows, the flow path is narrowed and narrowed, so-called surface throttling. The effect of this surface restriction stabilizes the flow between the two surfaces and also stabilizes the distance between the two surfaces. However, as described above, the gas bearing rigidity characteristic as an effect of the restriction is limited to about 1/10 or less of the gas bearing rigidity characteristic set when the gap amount is accurately controlled.

  Returning to FIG. 5 again, the plurality of flat plate movable elements 50 are arranged around the central axis 32 in a stacked manner along the axial direction. Then, a gap control gas flows from the communication hole 34 on the side surface of the central shaft 32 into the gap between the adjacent flat plate movable elements 50. Further, a gap between the upper surface of the flat plate mover 50 located on the uppermost layer of the plurality of flat plate movers 50 and the bottom surface of the objective pad 22, the lower surface of the flat plate mover 50 located on the lowermost layer, and the housing body Similarly, the clearance control gas flows through the communication hole 34 on the side surface of the central shaft 32 in the clearance between the upper surface 26 and the upper surface 26.

  Now, assuming that N flat plate movers 50 are arranged in a storage space formed by the objective pad 22, the telescopic wall portion 24, and the housing body 26, the space between the objective pad 22 and the housing body 26 is assumed. N + 1 gaps are formed, and a gap control gas flows through these gaps. The movable table 104 is subjected to the weight of the vibration isolation table 202, and a pressing force is applied to the objective pad 22.

Here, when the pressing force F acts toward each flat plate movable element 50 by the objective pad 22, the flow of gas flowing through these gaps shows an action as a so-called gas bearing. That is, by controlling the gas pressure P _S of the clearance control gas, while balanced with the pressing force F can be adjusted amount of these gaps, thereby, the axial direction of the central axis 32 of the flat plate armature 50, i.e. the objective The pad 22 can be finely moved in the direction in which the height position of the movable table 104 is changed. Then, by changing this minute movement with time, a minute acceleration as a second-order time differential amount of the gap amount can be given to the movable table 104, and thereby the movable table 104 can be minutely vibrated.

For example, if the gas pressure P _S of the gap control gas is changed by + ΔP, the amount of each gap can be changed by + Δs, and this Δs / ΔP is the shape of the flat plate mover 50 and the gap between adjacent flat plate movers 50. The gas pressure P _S , the pressing force F, and the like can be experimentally determined. Here, since Δs / ΔP is determined for each gap, if the number of gaps is N + 1, the total axial movement amount of the plurality of flat plate movable elements 50 is (N + 1) × Δs, and the movement amount However, it can be adjusted by increasing or decreasing the number of the flat plate movable elements 50.

  As described above, in the storage space formed by the objective pad 22, the telescopic wall portion 24 and the housing body 26, the gap control gas is supplied from the communication hole 34 on the side surface of the central shaft 32, and a plurality of flat plate movable It flows in a gap between the children 50. The flowing gas flows out into a space 49 between the outer periphery of the plurality of flat plate movable elements 50 and the stretchable wall portion 24. As shown in FIG. 3, the space 49 is connected to the gas discharge groove 44 of the objective pad 22 and the exhaust port 48 in the housing body 26 and is sucked to the outside. It can be called a flow path. As described above, the space 49 serving as the gas exhaust flow path collects the gas from the gas discharge groove 44 of the objective pad 22 and the gas from the gaps between the flat plate movable elements 50 to collect the external exhaust device 45. Lead to. Thereby, gas can be collected efficiently.

Next, the control unit 206 in FIG. 1 will be described. The control unit 206 compares the acceleration of the vibration of the vibration isolation table 202 detected by the acceleration detector 204 with an appropriate command value, and controls the gas pressure control valve 60 so as to make the deviation zero, so that the gap It has a function of periodically changing the gas pressure of the control gas minutely. As an appropriate command value, acceleration = 0 can be set. Further, it is preferable that the vibration frequency of the vibration isolation table 202 is detected and the gas pressure of the gap control gas is periodically minutely changed at the vibration frequency. Thus, the gap control gas whose gas pressure P _S is periodically changed minutely according to the detected acceleration is supplied to the Z-direction minute vibration unit 10. As a result, the objective pad 22 vibrates minutely, causing the movable table 104 to vibrate slightly, canceling out the minute vibrations of the vibration isolation table 202 and performing vibration isolation. The acceleration detector 204 may be attached to the movable table 104 in addition to the vibration isolation table 202, or may detect the acceleration of the objective pad.

  As described with reference to FIG. 3, the minute vibration control device 100 includes the gas pressure support mechanisms 12, 14, and 16 having the same functions as the gas pressure support mechanism 20 and the gas pressure control valve 60 that constitute the Z-direction minute vibration unit 10. , 18 and gas pressure control valves 13, 15, 17, 19 are provided, so that the movable table 104 can be given minute vibrations in the X direction and minute vibrations in the Y direction. These X-direction minute vibration and Y-direction minute vibration are also made so that the control unit 206 cancels out the detected X-direction vibration and Y-direction vibration by using the acceleration detector 204 as a three-dimensional detection device. It is possible to control the gas pressure of the gap control gas.

  In the above, the opening 52 at the center of the flat plate movable element 50 and the central shaft 32 are not directly fixed, and the flat plate movable elements 50 are slid by the central shaft 32 so as not to shift in the radial direction. Is retained. In addition to this, the flat plate movable element 50 can be held by a viscoelastic material on the central axis. As the viscoelastic material, plastic, rubber or the like can be used. In this case, the central axis may be a simple cylindrical axis or prismatic axis instead of the star-shaped shape.

  FIG. 9 is a diagram showing an example in which a flat plate movable element is held on the central axis using a cloud spring. As with the flat plate movable element 70 described with reference to FIG. 8, the flat plate movable element 71 is provided with a hollow 77 on the inner diameter side and a wide groove 79 extending in the radial direction from the hollow 77. A cloud spring 75 is provided as a thin plate member that connects the inner diameter side portion of the circular plate 73 and the outer shape of the central shaft 33. Here, the cloud spring 75 is used as a holding member whose rigidity with respect to the axial displacement of the central shaft 33 is small with respect to the radial displacement.

  As a pattern of the cloud spring 75, the overall shape is formed by appropriately combining the shape of the portion extending in the radial direction and the shape of the portion extending in the circumferential direction. Specifically, it has a complicated and winding shape, whereby a window-like opening is formed between the patterns, and gas can flow through the opening window. Such a cloud spring 75 can be obtained by etching a thin metal plate into a predetermined pattern. For example, it can be obtained by performing etching or electric discharge machining on a SUS plate having a thickness of about 0.1 mm. A cloud spring is a simple name used because its shape pattern is twisted and resembles a cloud shape, and any other spring can be used if it has a small rigidity in the axial direction and a large rigidity in the radial direction. It may be a designation.

  An appropriate adhesive can be used for the connection between the cloud spring 75 and the disk 73 of the flat plate movable element 70 and the connection between the cloud spring 75 and the central shaft 33. In some cases, the thickness of the circular plate 73 can be reduced and integrated with the cloud spring 75.

  By adopting such a configuration, the flat plate movable element 71 held by the central shaft 33 via the cloud spring 75 is relatively easy to move in the axial direction of the central shaft 33, but in the radial direction of the flat plate. That is, it is relatively difficult to move in the direction perpendicular to the axial direction of the central axis 33. In other words, the flat plate movable element 71 has a characteristic that the axial direction of the central shaft 33 is the thrust direction and the degree of freedom in the thrust direction is large, but the movement in the radial direction perpendicular thereto is restricted. Here, the central axis 33 may be a simple cylindrical axis or prismatic axis.

  In the above description, the gap control gas is blown out from the blowout port at the center of the objective pad. However, it is possible to adopt a structure in which the blown out gas has a rectifying property as a smooth flow. FIG. 10 shows some examples of an objective pad that can impart rectification to the gas to be blown out.

  FIG. 10A shows a case where a porous plate 84 is provided on the upper surface side of the objective pad 80. The gap control gas supplied from the central opening 82 is rectified by passing through the porous plate and becomes a smooth flow.

  FIG. 10B shows a case where a surface stop 94 is provided on the upper surface of the objective pad 90. As the surface diaphragm, the shallow groove structure or the like described in FIG. 4 can be used, or a surface diaphragm having another configuration may be used. The flow of the gap control gas supplied from the central opening can be made smooth by the surface restriction. In addition, an appropriate orifice diaphragm or the like can be provided as the front stage diaphragm 92 at the center opening.

  FIG. 10C shows a case where a tapered groove 98 is provided on the upper surface of the objective pad 96. As the taper groove 98, a groove having a groove depth that gradually decreases from the center opening toward the outer periphery can be used. The flow supplied from the central opening by the taper groove 98 gradually spreads toward the outer periphery, whereby a smooth flow can be obtained. Here too, the front stop 92 can be used in the central opening. A stepped groove or the like can be used instead of the tapered groove.

  In the configuration described with reference to FIG. 5, a gas discharge groove 44 is provided in the objective pad 22, and the gas blown out from the gas outlet 30 is sucked by the exhaust device 45 via the space 49 inside the housing portion 21. It collects from the groove 46. A gas suction groove 46 is further provided on the outer peripheral side of the gas discharge groove 44. According to this configuration, the gas used for floating the movable table 104 in the gas pressure support mechanism 20 does not leak to the outside of the gas pressure support mechanism 20. Therefore, the operation | movement etc. under pressure reduction are attained. On the other hand, the gas suction groove can be omitted in a system in which it is not necessary to strictly recover the gas used for floating.

  In the above description, the acceleration applied to the movable table 104 is described as being due to a change in the gas pressure of the gap control gas. In this case, the gap through which the gas flows changes around the nominal standard gap amount, and the upper limit of the acceleration may be limited by the nominal standard gap amount. Therefore, separately from the gap control gas, it is preferable to supply a bias control gas for providing a bias support force that increases the support force for supporting the movable table 104.

  FIG. 11 is a diagram showing a configuration of a micro vibration control device 110 that includes a bias control gas pressure control valve 152 in addition to the gap control gas pressure control valve 150, and can thereby apply a bias support force to the movable table 114. It is. Elements similar to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this minute vibration control device 110, an independent objective pad is omitted as compared with the minute vibration control device 100 of FIG. 3, and a portion on the bottom surface side of the movable base 104 serves as an object pad that gives minute vibration to the support target. It has the function of Of course, an objective pad may be provided as in FIG. Here, the bottom surface of the movable platform 104 having the function of the objective pad and the housing portion 112 are connected by the bellofram 116. The belofram 116 is a flexibly deformable connecting member that hermetically connects the movable table 104 having the function of an objective pad and the housing 112, and is made of, for example, rubber or plastic rubber.

  In this way, one sealed space is formed by the bellophram 116, the bottom surface of the movable base 104, and the inner wall portion of the housing portion 112. This sealed space corresponds to the sealed space inside the gas pressure support mechanism 20 in FIG. In FIG. 5, the objective pad 22 can be moved in the Z direction by the telescopic wall 24, but the movement in the X direction and the Y direction is restricted. On the other hand, since the configuration of FIG. 11 includes the bellophram 116, the movable base 104 can move in three directions XYZ.

A plurality of flat plate movers 50 are arranged in one sealed space formed by the bellophram 116, the bottom surface of the movable base 104, and the inner wall portion of the housing portion 112. A space 120 is provided between the outer periphery of the plurality of flat plate movable elements 50 and the inner wall portion of the housing portion 112, and the gas from the bias control gas pressure control valve 152 is supplied to this space. The gas pressure supplied from the bias controlling gas pressure control valve 152 and P _B, if the area of the gas pressure receiving surface of the bottom surface of the movable base 104 and the A _B in the space 120, biasing supporting force of P _B × A _B is It is given to the movable table 104. As a result, the limitation on the acceleration applied to the movable table 104 due to the change in the gas pressure supplied from the gap control gas pressure control valve 150 can be relaxed.

  In FIG. 11, the configuration in which the bias support force in the Z direction is applied to the movable table 104 has been described. However, the same configuration is applied to the gas pressure support mechanisms 12, 14, etc. , A bias supporting force in the Y direction can be provided.

It is a figure which shows the structure of the vibration isolation system in which the gas pressure control type | mold micro vibration control apparatus of embodiment which concerns on this invention is used. It is a top view which shows the structure of the micro vibration control apparatus in embodiment which concerns on this invention. It is front sectional drawing of the micro vibration control apparatus in FIG. In embodiment concerning this invention, it is a top view of a gas pressure support mechanism. In embodiment which concerns on this invention, it is a figure which shows the structure of the Z direction micro vibration part containing a gas pressure support mechanism and a control part. In embodiment which concerns on this invention, it is a figure which shows the central axis which comprises a gas pressure support mechanism. In embodiment which concerns on this invention, it is a figure which shows the flat plate needle | mover which comprises a gas pressure support mechanism. In embodiment which concerns on this invention, it is a figure explaining the structure of another flat needle | mover. In embodiment which concerns on this invention, it is a figure which shows the example which hold | maintains a flat needle | mover to a central axis using a cloud shaped spring. In embodiment which concerns on this invention, it is a figure which shows the other example of an objective pad. In an embodiment concerning the present invention, it is a figure showing composition of a minute vibration control device which can give bias support power to a support subject.

Explanation of symbols

  10 Z direction minute vibration part, 12, 14, 16, 18, 20 Gas pressure support mechanism, 13, 15, 17, 19, 60 Gas pressure control valve, 21 Housing part, 22, 80, 90, 96 Objective pad, 23 Objective top surface, 24 Telescopic wall, 26 Housing body, 30 Gas outlet, 32, 33 Central axis, 34 Communication hole, 38 Gas supply port, 42 Narrow groove, 44 Gas exhaust groove, 45 Exhaust device, 46 Gas suction Groove, 47 vacuum source, 48 exhaust port, 49,120 space, 50, 70, 71 flat plate mover, 52, 72, 73 disc, 52, 54, 74 opening, 40, 56, 58, 76, 77 indentation , 75 Cloud spring, 78, 79 Wide groove, 82 Center opening, 84 Porous plate, 92 Pre-stage restriction, 94 Surface restriction, 98 Tapered groove, 100, 110, 200 (Gas pressure control type) Micro vibration control device 102 casing unit, 104, 114 movable base, 112 casing unit, 116 belofram, 150 clearance control gas pressure control valve, 152 bias control gas pressure control valve, 200 vibration isolation system, 202 vibration isolation table, 204 acceleration detection Device, 206 control section, 210 mounting section.

Claims (8)

The gas blowout part possess the objective top surface facing the supporting object, an objective pad flowing gas to the objective gap between the objective top and the supporting object,
It has a through window that can be a gas flow, a plurality of flat plate-friendly Doko arranged aligned parallel to the pad back surface opposite the objective upper surface of the objective pads,
A housing portion that accommodates the plurality of flat plate movable elements so as to be movable along the alignment axis direction in which the movable plates are aligned;
A gas blowout part of the objective pad, and the pad-side gap is a gap between the through window of the flat plate armature, a leading-edge-side flat plate armature and a pad rear surface facing the pad back surface of the plurality of flat plate-Friendly Doko, the gap between the movable element which is a gap between the adjacent flat plate-friendly Doko, the bottom surface of the rearmost end side flat plate armature and a housing part facing the bottom surface of the housing portion of the plurality of flat plate-friendly Doko A gap control gas supply means for supplying a gap control gas to the bottom surface side gap which is a gap of
With
The objective pad is a surface diaphragm that extends from the gas blowing portion toward the outer peripheral side, and has a predetermined value that allows the gas bearing rigidity characteristics related to the amount of change in the object gap to change in the gas pressure to control the object gap amount. ,
Each flat plate mover has a positive sign in the gas bearing stiffness characteristic related to the amount of change in each mover gap with respect to a change in gas pressure, and is set to 1/10 or less of a predetermined value of the gas bearing stiffness characteristic in the objective pad. Each has a gas restrictor,
Gas pressure control type micro vibration control, which controls the gas pressure of the gap control gas and finely vibrates the support object while adjusting the gap distance while balancing with the pressing force from the support object. apparatus. In the gas pressure control type micro vibration control device according to claim 1,
The objective pad has a gas discharge part for discharging the gas flowing from the gas blowing part and flowing through the gap between the support object and the upper surface of the objective,
The housing part has an outer peripheral side space provided along the axial direction on the outer peripheral side of the plurality of flat plate movers inside,
A gas pressure control type micro vibration control device, wherein the gas discharge unit is connected to an external exhaust device through a space on the outer peripheral side. In the gas pressure control type micro vibration control device according to claim 1,
The housing part has an outer peripheral side space provided along the axial direction on the outer peripheral side of the plurality of flat plate movers inside,
A gas pressure control type micro-vibration control device comprising bias gas supply means for supplying a gas having a predetermined gas pressure to an outer peripheral side space and applying a predetermined bias support force to a support object. In the gas pressure control type micro vibration control device according to claim 3,
A gas pressure control type microvibration control device comprising: a bellophram made of rubber or plastic rubber, wherein a support object or an objective pad and a casing are connected in an airtight manner. In the gas pressure control type micro vibration control device according to claim 1,
The objective pad has a plurality of fine grooves extending from the gas blowing portion toward the outer peripheral side as a surface diaphragm,
Each flat plate movable element is a plurality of grooves extending from the through window toward the outer peripheral side as a gas constriction portion, and has a groove width wider than a narrow groove of the objective pad, and a groove depth is deep. Pressure control type micro vibration control device. In the gas pressure control type micro vibration control device according to claim 1,
A central support shaft that is provided inside the housing and supports the center of each flat plate mover, and is supported via a support member that has a displacement rigidity in the alignment axis direction smaller than that in the radial direction. A gas pressure control type microvibration control device comprising a central support shaft. In the gas pressure control type micro vibration control device according to claim 1,
A gas pressure control type microvibration control device comprising: a control unit that acquires acceleration of a support object or an objective pad and controls a gas pressure of a gap control gas according to the acquired acceleration. In the gas pressure control type micro vibration control device according to claim 1,
A plurality of objective pads are provided for a support object so as to support the support object in directions of three axes perpendicular to each other.

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