JPH10220527A - Vibration control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To positively prevent horizontal dislocation by damping vibration with resiliency generated by the movement of a contact position between the lower face of a supported member and a cylindrical supporting part caused by slight horizontal vibration of the bottom part of a piston and the lower end of a rod when the piston is oscillated receiving an external force. SOLUTION: A vibration control device B is so constituted that when vertical vibration is transmitted from a floor or the like to a support 2, the vertical vibration is transmitted to a case 11, whereas when horizontal vibration is transmitted to the support 2, the horizontal vibration is transmitted to the case 11 and then transmitted to a piston 17 through a diaphragm 13. However, a plate supporting member 22 or the like fixed to a rod 19 in a piston 17 is going to rest in its original position by inertial force, and the upper part of the piston 17 is vibrated with large amplitude in a horizontal direction, while the lower part is vibrated with small amplitude. At this time, the rod 19 is inclined, and a supported member 24 and a base plate 6 are slightly lifted. Force at this time becomes restoring force to damp the vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member provided between a supported member such as a member or a device which is adversely affected by the transmission of vibration and a supporting member for supporting the member. The present invention relates to a vibration isolator for preventing transmission to a supported member. Such an anti-vibration device can be used by disposing it between a charged particle beam device (scanning electron microscope, nuclear magnetic resonance device, etc.) and a supporting device that supports the device. In this case, the vibration isolator can prevent harmful vibration from being transmitted from the support device to the charged particle beam device.

[0002]

2. Description of the Related Art A charged particle beam apparatus, such as a scanning electron microscope, which performs a precise operation on a sample is supported by a support member via a vibration isolator which absorbs horizontal and vertical vibrations. Base plate and this base plate
And a precision working device that performs precision work on the sample held by the sample holding device. On the base plate, a device for finely moving the sample moves and rotates the sample in a horizontal plane and in a vertical axis direction (electron beam scanning direction) with high precision, from various directions. Samples need to be observed and analyzed. In such a charged particle beam device, when the vibration from the outside is transmitted to the sample holding device, the observation result of the sample and the analysis result become inaccurate,
Adverse effects occur. Further, the charged particle beam apparatus is manufactured with high precision in order to analyze very fine portions. For this reason, the transmission of vibration from the outside causes an error to occur in the charged particle beam apparatus that is precisely adjusted. Therefore, in order to obtain good observation and analysis results, the anti-vibration performance of the anti-vibration device becomes important. The following technology (J01) is conventionally known as the above-mentioned vibration damping device.

(J01) Diaphragm type air spring vibration isolator A conventionally used diaphragm type air spring vibration isolator seals an opening at an upper end of a case filled with compressed air with a diaphragm and a supported member. The diaphragm and the supported member are configured to be supported by compressed air. In this vibration isolator, vertical vibration is absorbed by compressed air, but the horizontal vibration isolation effect is not sufficient. FIG. 8 is a diagram showing a horizontal vibration transmissibility of a conventional vibration isolator, FIG. 8A is a diagram showing a vibration transmissivity of a different conventional vibration isolator, and FIG. 8B is a diagram of a technique described in Japanese Patent Application Laid-Open No. 8-170689. It is explanatory drawing of a vibration transmissibility. In FIG. 8A, A indicates the horizontal vibration transmissibility of the vibration isolator (J01). In FIG. 8, if the vibration transmissibility is 0 dB or more,
It means that there is no vibration damping action, and if it exceeds 0 dB, it means that vibration is amplified and transmitted by resonance. As can be seen from FIG. 8A, the resonance frequency of the vibration isolator of (J01) is about 2 Hz. In a vibration isolator having such characteristics, there is no vibration isolation effect for vibration of about 1 Hz.

Conventionally, the following vibration isolator is known as a vibration isolator having an enhanced horizontal vibration isolating effect. (J02) (Technique described in Japanese Patent Publication No. 62-7409) This publication describes a vibration isolator using a piston. This vibration isolator has a case for forming a compressed air chamber having an opening formed on the upper surface. In the opening,
The upper end of a bottomed cylindrical piston having a rod receiving hole whose upper end is opened is connected and supported by the annular diaphragm. Compressed air is filled inside the case in which the upper opening is closed by the annular diaphragm and the piston. The piston and the diaphragm are lifted by the compressed air. The lower part of the support rod is inserted into the rod receiving hole of the piston from the upper surface opening, and the lower end of the support rod is supported by the bottom of the rod receiving hole of the piston. A support plate on a flat plate is connected to an upper end of the support rod. When a supported member (for example, a base plate supporting an electron microscope) is supported by the vibration isolator having the above-described configuration, the vibration isolator is provided below four corners of the supported member (base plate). It arrange | positions and supports a to-be-supported member (base plate) on the said support plate of each vibration isolator.

[0005] Since the vibration isolator is supported on the floor of a building or the like, when the building or the like vibrates, the vibration is transmitted to the case of the vibration isolator. Vertical and horizontal vibrations of the case of the vibration isolator are absorbed by the compressed gas inside the case. However, part of the vibration is transmitted to the piston via the diaphragm, and transmitted from the piston to the supported member (base plate) via the support rod and the support plate. As shown in FIG. 8B, the horizontal resonance frequency of the anti-vibration device of (J02) is about 1.2 Hz, so when a vibration of about 1.2 Hz occurs, the vibration is supported. There is no vibration damping effect because it is transmitted to the member. Actually occurring vibrations include vibrations of about 1 Hz, and there is no vibration damping effect against vibrations of such a frequency. Therefore,
A vibration isolator having a smaller resonance frequency is desired.

[0006] The following technology (J03) is known as a vibration isolator with a further reduced resonance frequency. (J03) Technique described in JP-A-8-170689 In this publication, the upper surface of the support plate (load disk) at the upper end of the support rod of (J02) is formed into a spherical surface, and the lower surface of the supported member is supported by the spherical surface. An anti-vibration device is described. Specifically, the following techniques (a) to (c) are shown. (A) Technology in which one of the upper surface of the load disk and the lower surface of the supported member is formed as a spherical surface and the other is formed as a flat surface. (B) The lower surface of the supported member supported by the spherical surface of the upper surface of the load disk is formed as a concave spherical surface. Technology (c) The lower surface of the supported member supported by the spherical surface of the upper surface of the load disk is formed in a flat surface, and the positioning member and the elastic body are formed so that the contact position (support point) between the spherical surface and the flat surface does not move. Technique of Providing Holding Member The vibration isolator of this (J03) has, as shown in FIG.
It is described that the resonance frequency can be reduced to about 0.5 Hz. When the resonance frequency is reduced to about 0.5 Hz, there is an anti-vibration effect even for vibration of about 1 Hz.

[0007]

[Problems to be solved by the invention]

(Problem of the above (J03)) In the technique of the above (J03), since the support is made by using a spherical surface, point contact occurs. For this reason, there is a problem that the contact pressure is increased, the contact portion is easily worn or deformed, and it is difficult to maintain a stable operation for a long time. This problem becomes particularly large as the weight of the supported member increases. According to the technique (a) of (J03), when vibration occurs, the contact between the upper surface of the load disk and the lower surface of the supported member is a contact between the spherical surface and the flat surface. On the other hand, the spherical surface rolls. Then, there is a problem that the contact position between the spherical surface and the flat surface slightly shifts between when the vibration is generated and when the vibration is completed. For this reason, there has been a problem that the horizontal position of the supported member supported by the load disk is gradually reduced. In the technique (b), a spherical surface must be formed on both the upper surface of the load disk and the lower surface of the supported member. There is a problem that the spherical machining is troublesome and costly. In the technique (c), since the holding member made of an elastic body exerts a resisting force on the rolling of the spherical surface of the load disk on the flat surface of the supported member, the resonance frequency is increased. There is a point. That is, in this case, as shown in FIG. 8B, the ideal resonance frequency of 0.5 Hz actually increases to about 0.9 Hz.

[0008] The base plate supporting the electron microscope is supported by a vibration isolator, and the place where the electron microscope and the base plate are installed is a floor or the like inside a building. The floor or the like of such a building may be oscillated in the horizontal direction in a direction that is easy to vibrate (a direction that is easy to vibrate) and a direction that is hard to vibrate (in a direction that is difficult to shake). In transmission electron microscopes, scanning electron microscopes, etc., the way of supporting the sample for microscopic analysis and the overall structure differ greatly between the front and rear direction and the left and right direction, and the sensitivity to floor vibration also differs greatly depending on the direction. There are many. In such a case,
It is not necessary to lower the resonance frequency for vibrations in all directions in the horizontal direction. If a low resonance frequency can be obtained only for vibrations in a predetermined horizontal direction, there may be a sufficiently practical effect.

The present invention has been made in view of the above circumstances, and has the following content as an object. (O01) In a vibration isolator for supporting a supported member by a supporting portion, it is possible to prevent a displacement of the supported member supported by the supporting portion in a horizontal direction. (O02) To provide a vibration isolator having a resonance frequency for vibration in a predetermined horizontal direction lower than 1 Hz and easy to manufacture. (O03) To provide an anti-vibration device which operates stably for a long period of time even if the supported member has a large weight.

[0010]

Next, the present invention devised to solve the above-mentioned problems will be described. The elements of the present invention are used to facilitate correspondence with the elements of the embodiments described later. , The reference numerals of the elements of the embodiment are enclosed in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described below is to facilitate understanding of the present invention and not to limit the scope of the present invention to the embodiments.

(1st invention) In order to solve the aforementioned problem,
(A01) A case (11) having a piston insertion opening (11a) at an upper end thereof, and (A02) the piston according to the first invention of the present application, characterized by the following requirements. A piston (17) which is inserted into the case (11) from the insertion opening (11a) and has a rod receiving hole (17b) opened at the upper end, (A03) the outer edge portion is the case
A diaphragm (13) which is fixed to the outer periphery of the piston insertion opening (11a) and whose inner edge is fixed to the outer periphery of the upper end of the piston (17) to seal the piston insertion opening (11a); (A04) The case (11) filled with compressed gas inside the case (11) sealed by the diaphragm (13), (A05) the lower end is rotatably supported by the bottom of the rod receiving hole and the upper end is A cylindrical support (2) having an arc-shaped surface protruding upward
3) a rod (19) for supporting, (A06) a planar supported portion (24b) supported by the cylindrical support portion (23).
(A07) a distance r between the lower end of the rod (19) and the surface of the cylindrical support (23);
With respect to the radius of curvature R of the surface of the cylindrical support (23).
Are the cylindrical support portions (23) set so that R> r.

(Operation of the First Invention) In the vibration isolator of the first invention of the present application having the above-mentioned features, the case (11) has a piston insertion opening (11a) at the upper end thereof. A piston (17) having a rod receiving hole (17b) having an open upper end is inserted into the case (11) from the piston insertion opening (11a). The outer edge is the case
The diaphragm (13), which is fixed to the outer periphery of the piston insertion opening (11a) and whose inner edge is fixed to the outer periphery of the upper end of the piston (17), seals the piston insertion opening (11a). I do. The diaphragm (1
The diaphragm (13) and the piston (17) are supported in a lifted state by the compressed gas filled in the case (11) sealed by (3). A rod (19) whose lower end is rotatably supported at the bottom of the rod receiving hole supports a cylindrical support (23) having an arc-shaped cross-section surface projecting upward at the upper end thereof. The planar supported portion (24b) of the supported member (24) is supported by the tubular support portion (23).

When the case (11) vibrates in the vertical direction, the compressed gas (air spring) sealed in the case (11) absorbs the vertical vibration of the case (11). Vibration is hardly transmitted to the supported member (24) and the like.

When the case (11) vibrates, the vibration is transmitted to the case (11) of the vibration isolator and further transmitted to the piston (17) via the diaphragm (13). The piston (17) to which the vibration has been transmitted tends to reciprocate in the horizontal direction in accordance with the vibration. However, at this time, the supported member tends to stay still at the original position due to the inertial force. At this time, the bottom of the piston (17) supported by the flexible diaphragm (13) receives the load of the supported member (24) via the lower end of the rod (19). Therefore, the horizontal movement distance of the bottom of the piston (17) is smaller than that of the top of the piston (17). In other words, the upper portion of the piston (17) swings in accordance with the vibration, with the bottom portion hardly moving. That is, the piston (1
The horizontal amplitude at the bottom of 7) is extremely small. The vibration having a small amplitude at the bottom of the piston (17) is caused by the rod (1).
The transmitted vibration is transmitted to the supported member (24) via 9), and the transmitted vibration is extremely small.

A cylindrical support (23) supported on the upper end of the rod (19) supports the lower surface of the supported member (24). When the piston (17) swings as described above, the bottom of the piston (17) and the lower end of the rod (19) slightly vibrate horizontally as described above. When the direction of vibration of the lower end of the rod (19) is a vibration in the circumferential direction (direction perpendicular to the axis) on the surface of the cylindrical support member (23), the vibration causes the rod (19) to move into the cylindrical shape. The small support member (23) makes a small reciprocating rotation while making point contact with the supported member (24). By this reciprocating rotation,
The horizontal vibration of the lower end of the rod (19) is hardly transmitted to the supported member (24).

The contact position between the lower surface of the supported member (24) and the cylindrical support portion (23) is moved by the small reciprocating movement of the lower end of the rod (19). In that case, R
> R, the contact position is slightly lifted upward when the rod (19) rotates. The lower surface of the lifted supported member (24) and the cylindrical support portion (2
The contact position of 3) is such that the supported member (2
It returns to the original height position (height position of the initial point contact position) where the potential energy is low in 4). The cylindrical support part (23) is a flat supported part (24b) on the lower surface of the supported member (24).
The contact position before the rotation and the contact position after the rotation are the same because the cylindrical support portion (23) rotates around the axis of the cylindrical support portion (23) while being in contact with the shaft. Therefore, when the vibration direction of the lower end of the rod (19) is the vibration in the circumferential direction (the direction perpendicular to the axis) on the surface of the cylindrical support member (23), the cylindrical support portion (23) The position of the supported member (24) in the horizontal direction does not move. Therefore, the horizontal vibration is hardly transmitted to the supported member (24), and the horizontal displacement of the cylindrical support portion (23) can be prevented.

If the vibration direction of the lower end of the rod (19) is the vibration in the axial direction (direction perpendicular to the circumferential direction) of the cylindrical surface of the cylindrical support member (23), the vibration is The power is directly transmitted from the rod (19) to the supported member (24) supported by the cylindrical support (23). In this case, the vibration transmissibility of the vibration isolator of the first aspect of the present invention is not particularly different from that shown in FIG. That is, the vibration damping device of the first invention has a large vibration damping action against the circumferential vibration (direction perpendicular to the axis) of the cylindrical surface of the cylindrical support portion (23). Therefore, the direction in which the supported member (24) is likely to vibrate is detected, and the direction in which the supported member (24) easily vibrates and the direction in which the cylindrical support (2) is detected.
If the anti-vibration device is arranged so that the circumferential direction of 3) coincides, the anti-vibration effect increases.

(Second Invention) A vibration isolator according to a second invention of the present application has the following requirements.
01) Case with a piston insertion opening (11a) at the upper end
(11), (B02) The piston insertion opening (11
a) The piston (1) having a rod receiving hole (17b) which is inserted into the case (11) from above a) and has an opening at the upper end.
7), (B03) the outer edge is fixed to the outer periphery of the piston insertion opening (11a) of the case (11) and the inner edge is fixed to the outer periphery of the upper end of the piston (17) to insert the piston. Diaphragm (13), which seals the opening (11a), (B04) the case (11), which is filled with a compressed gas inside the case (11) sealed by the diaphragm (13); A cylindrical support part (23) rotatably supported at the bottom of the housing hole (17b) and having an arc-shaped cross-sectional surface protruding upward at the upper end;
(B06) The supported member (27) having a supported portion formed on a cylindrical concave surface (27b) supported by the cylindrical support portion (23);
7) The lower end of the rod (19) and the cylindrical support (23)
The cylindrical support (23), wherein a radius of curvature R of the surface of the cylindrical support (23) is set so that R> r with respect to a distance r from the surface.

(Operation of the Second Invention) The vibration isolator of the second invention of the present application having the above-mentioned features has the same configuration as the first invention, and the operation of the common component is as follows. The first
This is the same as the operation of the invention. The description of the same operation as in the first invention is omitted. In the vibration damping device of the second invention of the present application, when the direction of vibration of the lower end of the rod (19) is vibration in the circumferential direction (direction perpendicular to the axis) on the surface of the cylindrical support member (23), , The cylindrical support part (23) and the supported member (2
The supported member (27) swings about the position where the cylindrical concave surface (27b) of (7) comes into contact. Therefore, the vibration of the lower end of the rod (19) is hardly transmitted to the supported member (27). Further, the cylindrical support portion (2
3) swings while being in line contact with the cylindrical concave surface (27b) of the supported member (27), so that the horizontal position of the supported member (24) supported by the cylindrical support portion (23) is changed. You will not move. Therefore, the cylindrical support member (2
3) Vibration in the circumferential direction (perpendicular to the axis) of the surface is hardly transmitted to the supported member (24), and the displacement of the cylindrical support portion (23) in the horizontal direction can be prevented.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

Next, examples (embodiments) of embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. (Embodiment 1) FIG. 1 is an overall explanatory view of a case where an SEM (Scanning Electron Microscope, scanning electron microscope) is supported by an anti-vibration device having Embodiment 1 of the present invention. FIG.
FIG. 2 is a plan view as viewed from above in FIG. FIG. 3 is an explanatory view of a vibration isolator provided with the first embodiment, and FIG.
FIG. 3B is an enlarged explanatory view of a plate supporting member. FIG. 4 is an operation explanatory view of the vibration isolator provided with the first embodiment, FIG. 4A is an operation explanatory view of a piston,
FIG. 4B is an explanatory view of the operation of the cylindrical support portion of the plate support member.

In FIGS. 1 and 2, on the floor 1, four vertical columns 2 arranged at four vertices of a quadrilateral as viewed in plan are fixed. An upper horizontal connection frame 3 is connected to the upper ends of the four columns 2, and a lower horizontal connection frame 4 is connected to the lower ends. The upper horizontal connection frame 3 and the lower horizontal connection frame 4 are each formed of four iron hollow prisms having respective ends welded to each other. A base plate 6 is supported above the column 2 via a vibration isolator B fixed to the upper end thereof, and a sample holding device 7 and a scanning electron microscope tube 8 are supported on the upper surface thereof.

In FIG. 3, the vibration isolator B supporting the base plate 6 is fixed at the upper ends of the four columns 2 by fixing screws 9. The inside of the case 11 of the vibration isolator B is hollow, and a piston insertion opening 11a is formed in the center of the upper end surface. A plurality of fixing screw holes 11b are formed in the outer peripheral edge of the piston insertion opening 11a. The inside of the case 11 is filled with compressed air, and a diaphragm fixing member 12 is disposed on the upper surface of the outer peripheral edge of the piston insertion opening 11a. A piston through-hole 12a is formed in the center of the diaphragm fixing member 12, and a fixing screw through-hole 12b is provided on the outer periphery thereof and at a position corresponding to the fixing screw hole 11b. A fixing screw 12c passes through the fixing screw through hole 12b and is screwed into the fixing screw hole 11b.
Thus, the outer peripheral end of the diaphragm 13 formed of a flexible member is sandwiched and fixed between the lower end surface of the diaphragm fixing member 12 and the upper end surface of the case 11. The inner peripheral end of the diaphragm 13 is fixed to a piston 17 by a fixing ring 14 and a fixing nut 16.

A diaphragm fixing portion 17a is provided on a lower end surface of a flange portion above the piston 17 inserted through the piston through-hole 12a and the piston insertion opening 11a, and a male screw is formed on an outer surface below the diaphragm fixing portion 17a. The upper end of the piston 17 is provided with a rod accommodation hole 17b that is open at the top. A rod holding ring 18 is disposed on the bottom side of the rod receiving hole 17b.
9 penetrates. A ball 21 is supported on the lower end of the rod 19. The spherical surface of the ball 21 contacts the bottom of the rod receiving hole to support the rod 19.

At the upper end of the rod 19 supported by the ball 21, a plate supporting member 22 is fixed vertically. The plate support member 22 is plate-shaped, and a cylindrical support portion 23 having a cylindrical surface smaller than the plate support member 22 is provided on an upper end surface thereof. Note that, instead of the cylindrical support portion 23 having the cylindrical surface, a cylindrical support portion having an elliptical surface can be employed, or an appropriate cylindrical support portion having a curved surface having a smooth cross-sectional shape can be employed. is there. A supported member 24 is supported above the cylindrical support portion 23. The supported member 24 is plate-shaped, has a plurality of fixing screw holes 24a, and has a planar supported portion 24b on the lower end surface. The flat supported portion 24b is in line contact with the curved surface of the cylindrical support portion 23. For this reason, the supported member 24 is hardened to make it hard to wear and to make it tough. The radius R of the curved surface of the cylindrical support portion 23 is determined by the distance between the point where the spherical surface of the ball 21 contacts the bottom of the rod receiving hole (hereinafter referred to as the center point) and the point where the line comes into contact (hereinafter referred to as rod rotation). (Referred to as radius) (see FIG. 4B). The supported member 24
Are fixed to the lower end surface of the base plate 6 by fixing screws 26 screwed into fixing screw holes 24a.

(Operation of the First Embodiment) Next, the operation of the first embodiment having the above-described configuration will be described. The base plate of the charged particle beam device is likely to vibrate (direction of large vibration) according to the structure of the charged particle beam device itself, the structure around the place where the charged particle beam device is installed, the position of a vibration source that is easily subject to vibration, and the like. In many cases, the overall vibration can be effectively reduced only by reducing the vibration in such a direction. The direction of the cylindrical support 23 is adjusted so that the axial direction of the cylindrical support 23 intersects perpendicularly. When vertical vibration is transmitted from the floor 1 or the like to the support 2,
The vertical vibration is transmitted to the case 11 of the vibration isolator B fixed to the upper end of the column 2. However, the vibration is absorbed by the compressed air (air spring), and the vibration is hardly transmitted to the piston 17 and the like. Therefore, almost no vertical vibration is transmitted to the base plate 6 via the plate supporting member 22. In FIG. 4A, when horizontal vibration is transmitted from the floor 1 or the like to the support 2, horizontal vibration is transmitted to the case 11 of the vibration isolator B fixed to the upper end of the support 2. The vibration transmitted to case 11 is
Piston insertion opening 11 through the diaphragm 13
It is transmitted from a to the inserted piston 17. The piston 17 tends to vibrate in the horizontal direction.

However, the plate support member 22 and the like fixed to the rod 19 accommodated in the piston 17 try to stop at the original position due to the inertial force. Since the load of the plate support member 22 and the like is supported by the rod receiving bottom of the piston 17 via the ball 21 of the rod 19, the horizontal movement distance of the bottom of the piston 17 is higher than the piston 17 Smaller. As a result, the upper part of the piston 17 supported by the flexible diaphragm 13 vibrates with a large amplitude in the horizontal direction, and the lower part vibrates with a small amplitude.

In FIG. 4B, the lower end of the rod 17 also vibrates in the horizontal direction with a lower amplitude due to the lower amplitude vibration of the lower portion of the piston 17. Even when the lower end of the rod 19 vibrates in the horizontal direction, the cylindrical support portion 23 of the plate support member 22 fixed to the rod 19 tends to remain at a position where it comes into line contact with the planar supported portion 24b. The rod 19 supporting the port support member 22 is inclined. When the rod 19 is inclined, since the radius R of the curved surface of the cylindrical support portion 23 is larger than the rod rotation radius r,
The supported member 24 and the base plate 6 supported by the cylindrical support 23 are slightly lifted. Since the supported member 24 and the base plate 6 try to stabilize in the direction of lowering the center of gravity, this becomes a restoring force, and the rod 19 returns to the center position (initial position). Therefore, even if the horizontal vibration is transmitted from the piston 17 to the lower end of the rod 19, the play supported by the rod 19
The vibration is hardly transmitted to the supported member 24 and the base plate 6 only because the cylindrical supporting portion 23 of the supporting member 22 swings like a pendulum while being in line contact with the planar supported portion 24b.

FIG. 5 is a graph showing the vibration transmission characteristics of the vibration isolator of the first embodiment. A graph A in FIG. 5 shows a vibration transmission characteristic of the cylindrical support member 23 with respect to a circumferential vibration, and a graph B shows a vibration transmission characteristic of the cylindrical support member 23 with respect to an axial vibration. As can be seen from FIG.
With respect to the vibration in the circumferential direction, the same vibration transmission characteristics (that is, the vibration-proof effect) as those of the conventional technology (J03) are obtained,
With respect to the vibration in the axial direction, a vibration transmission characteristic (that is, a vibration-proof effect) similar to that of the conventional technique (J02) can be obtained.

(Embodiment 2) FIG. 6 is an explanatory view of Embodiment 2 of the present invention and corresponds to FIG. In FIG. 6, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description is omitted. The second embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points.
In the second embodiment, the planar support portion 2 of the supported member 24
Instead of 4b, the cylindrical concave surface 27b of the supported member 27 is supported by the cylindrical support portion 23 of the plate support member 22. Therefore, horizontal vibration is generated by the piston 17.
Is transmitted to the lower end of the rod 19, and the lower end of the rod 19 vibrates with a small amplitude, the rod 19 swings while the cylindrical support portion 23 is in line contact with the cylindrical concave surface 27b. Therefore, the motion of the cylindrical support portion 23 that swings in response to the small-amplitude horizontal vibration of the lower end of the rod 19 is hardly transmitted to the cylindrical concave surface 27b and the supported member 27. Further, since the cylindrical concave surface 27b of the supported member 27 is supported by the cylindrical support portion 23, even if the cylindrical support portion 23 swings as described above when the vibration occurs, the vibration ends. At times, the positional relationship between the supported member 27 and the cylindrical support portion 23 always returns to the initial position. Therefore, the displacement of the supported member 27 and the base plate 6 in the horizontal direction is less likely to occur.

(Embodiments 3 and 4) FIG. 7 is an explanatory view of Embodiments 3 and 4 of a vibration isolator according to the present invention.
7A is an explanatory diagram of Embodiment 3 of the present invention, and FIG. 7B is an explanatory diagram of Embodiment 4 of the present invention. The anti-vibration device of the third embodiment shown in FIG. 7A is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points. 7A, in the third embodiment of the vibration isolator of the present invention, of the four cylindrical support members 23 that support the lower surfaces of the four corners of the base plate 6 respectively, two axial support members are connected by the rod 31. doing. The rod 31 has a round cross-sectional shape. By connecting the two cylindrical support members 23 with the rod 31, the axial and circumferential directions of the cylindrical support members 23 can be made the same. Each cylindrical support member 2
3 have the same circumferential direction, each cylindrical support member 2
3, the vibration transmission characteristics in the circumferential direction can be made uniform.
The anti-vibration device of the fourth embodiment shown in FIG. 7B is different from the first embodiment in the following points, but is different from the first embodiment in other points.
It is configured similarly to. In FIG. 7B, the rod 31
Has a rectangular cross-sectional shape. The anti-vibration device of the fourth embodiment has the same operation as that of the third embodiment.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention is applicable to anti-vibration devices other than scanning microscopes. (H02) The present invention can be changed to a plate supporting member and a supported member of various shapes such as a circle instead of using a square plate supporting member and a supported member. (H03) According to the present invention, instead of fixing the supported member to the base plate with the fixing screws, the member to be supported can be fixed by another fixing means such as an adhesive.

[0032]

The anti-vibration device according to the present invention has the following effects. (E01) In a vibration isolator in which a supported member is supported by a support portion provided at an upper end of a rod supported by a piston, a displacement of the supported member supported by the support portion in a horizontal direction can be prevented. . (E02) An easy-to-manufacture vibration isolator having a resonance frequency for vibration in a predetermined horizontal direction of about 0.6 Hz can be provided. (E03) It is possible to provide an anti-vibration device that operates stably for a long time even if the weight of the supported member is large.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of a case where an SEM (Scanning Electron Microscope, scanning electron microscope) is supported by a vibration isolator provided with Embodiment 1 of the present invention.

FIG. 2 is a plan view of FIG. 1 as viewed from above.

FIG. 3 is an explanatory view of a vibration isolator provided with the first embodiment, FIG. 3A is a longitudinal sectional view of the vibration isolator provided with the first embodiment,
FIG. 3B is an enlarged explanatory view of the plate supporting member.

4 is an explanatory view of an operation of the vibration isolator provided with the first embodiment, FIG. 4A is an explanatory view of an operation of a piston, and FIG. 4B is an explanatory view of an operation of a cylindrical supporting portion of a plate supporting member. is there.

FIG. 5 is a graph showing a vibration transmission characteristic of the vibration isolator of the first embodiment.

FIG. 6 is an explanatory diagram of Embodiment 2 of the present invention, and is a diagram corresponding to FIG.

FIG. 7 is an explanatory view of Embodiments 3 and 4 of the vibration isolator of the present invention. FIG. 7A is an explanatory view of Embodiment 3 of the present invention, and FIG. 7B is an explanatory view of Embodiment 4 of the present invention. FIG.

FIG. 8 is a diagram showing a horizontal vibration transmissibility of a conventional vibration isolator, FIG. 8A is a diagram showing a vibration transmissivity of a different conventional vibration isolator, and FIG. 8B is a Japanese Patent Application Laid-Open No. 8-170689. It is explanatory drawing of the vibration transmission rate of the technique of description.

[Explanation of symbols]

11: Case, 11a: Piston insertion opening, 13: Diaphragm, 17: Piston, 17b: Rod accommodation hole,
19: rod, 22: plate support member, 23: cylindrical support portion, 24, 27: supported member, 24b: planar supported portion, 27b: cylindrical concave surface

Claims (2)

[Claims] 1. A vibration isolator characterized by the following requirements: (A01) a case having a piston insertion opening at an upper end, and (A02) a case having a piston insertion opening inside said case. A piston having a rod-receiving hole which is inserted and opened at the upper end, (A03) the outer edge is fixed to the outer periphery of the piston insertion opening of the case, and the inner edge is fixed to the outer periphery of the piston upper end; A diaphragm for sealing the piston insertion opening, (A04) the case filled with compressed gas inside the case sealed by the diaphragm, (A05) a lower end rotatably supported by the bottom of the rod receiving hole and a lower end A rod for supporting a cylindrical support having an arc-shaped cross-section surface protruding upward, (A06) the supported member having a planar supported portion supported by the cylindrical support, (A07) the support With respect to the distance r between the de bottom and the cylindrical support portion surface, the curvature radius R of the cylindrical support part surface, the cylindrical support portion which is set to R> r. 2. A vibration isolator having the following requirements: (B01) a case having a piston insertion opening at the upper end, and (B02) a case having a piston insertion opening inside said case. A piston having a rod receiving hole which is inserted and opened at the upper end, (B03) the outer edge is fixed to the outer periphery of the piston insertion opening of the case, and the inner edge is fixed to the outer periphery of the piston upper end; A diaphragm for sealing the piston insertion opening, (B04) the case filled with compressed gas inside the case sealed by the diaphragm, (B05) a lower end rotatably supported by the bottom of the rod receiving hole and a lower end A rod for supporting a cylindrical support having an arc-shaped cross-section surface projecting upward, (B06) the supported member having a supported portion formed on a cylindrical concave surface supported by the cylindrical support, (B07) The cylindrical support portion wherein a radius of curvature R of the surface of the cylindrical support portion is set to R> r with respect to a distance r between the lower end of the rod and the surface of the cylindrical support portion.