JP7584866B2 - Vacuum seal valve connection mechanism - Google Patents

Description

The present invention relates to a connection mechanism for a vacuum sealing valve.

In devices that have a vacuum chamber, such as electron microscopes, a partition wall is provided to separate the inside of the vacuum chamber, and a vacuum seal valve is provided to seal an opening in the partition wall. In order to align the opening with the vacuum seal valve, the vacuum seal valve may be provided with a connection mechanism that adjusts the position between the shaft that transmits the driving force and the valve body that performs the sealing.

For example, Patent Document 1 discloses a connection mechanism in which part of the shaft is configured to be rotatable, thereby making it possible to adjust the height of the valve body fixed to the tip of the shaft. Lock nuts are provided above and below the rotating part, and the shaft is fixed to the valve body and bellows by the lock nuts.

JP 2016-66684 A

However, in the connection mechanism of Patent Document 1, although the height (connection length) is adjustable, the shaft and valve body are completely fixed by a lock nut, and any twisting or rotation of the valve body or shaft is directly transmitted to the bellows connected to the shaft, raising concerns that the bellows, which is vulnerable to rotational loads, may be destroyed.

The present invention was made in consideration of the above problems, and provides a connection mechanism for a vacuum sealing valve that allows the connection length to be adjusted and suppresses defects caused by rotation or twisting.

In order to solve the above problem, in one aspect of the present disclosure, a connection mechanism for a vacuum sealing valve that connects a first shaft member that is connected to a drive mechanism and driven, and a second shaft member that is connected to a valve body that seals an opening and transmits the drive of the first shaft member, includes a first connection member that is fixed to an end of the first shaft member and has a first engagement hole formed at an end facing the second shaft member, a second connection member that is fixed to an end of the second shaft member and is threadedly engaged with the first connection member, and has a second engagement hole formed at an end facing the first shaft member at a position that allows serialization with the first engagement hole, and an engagement member that engages with one of the first engagement hole or the second engagement hole and has a protruding portion that protrudes into the other engagement hole when engaged, and is configured so that the outer diameter of the protruding portion is smaller than the inner diameter of the other engagement hole.

According to this aspect, the first and second connecting members are screwed together to connect the two shafts after adjusting the connection length, and then the engaging member is engaged with the two serially arranged engaging holes, allowing the two shafts to rotate relative to each other by the diameter difference between the engaged engaging member and the other unengaged engaging hole while preventing rotation of the two shaft members. As in the past, when the two shafts are completely fixed using a fixing member such as a nut after adjusting the connection length, twisting and tilting cannot be corrected. In this case, since the shafts cannot be completely rotated, if they are fixed at an angle from the normal position, the valve body will seal the opening without being corrected and will remain tilted, resulting in a decrease in sealing performance. In addition, slight rotation due to shaft movement is transmitted directly to the bellows, damaging the bellows. In contrast, in this embodiment, the two shafts are connected with a slight amount of play that allows rotation, thereby suppressing problems caused by rotation and twisting.

In one embodiment, the one engagement hole that engages with the engagement member is a screw hole, and the engagement member is a headless bolt or a bolt with a head diameter smaller than the inner diameter of the other engagement hole. According to this embodiment, the engagement member can be easily engaged by screw engagement. In addition, even after disassembly, the engagement member and shaft can be placed in approximately the same position, making realignment very easy.

In one embodiment, at least one of the first and second engagement holes is configured to be provided in a plurality of positions on the same circle, with the axis of threaded engagement between the first and second connecting members as the center, at equal or unequal intervals. According to this embodiment, by providing a plurality of connectable positions on the same circle, it is possible to finely adjust the connection length more precisely.

In one embodiment, the first shaft member is connected to the drive mechanism via a connecting mechanism,
The first shaft member is configured to be connected to the connecting mechanism by screw engagement, and the screw engagement allows length adjustment at both ends of the first shaft.

The above configuration provides a vacuum sealing valve connection mechanism that allows the connection length to be adjusted and reduces problems caused by rotation or twisting.

1 is a schematic diagram of an electron microscope equipped with a vacuum sealing valve according to an embodiment of the present invention. FIG. FIG. 2 is a side view of the vacuum seal valve (some components are not shown for the purpose of illustration). FIG. 2 is a vertical cross-sectional view of the vacuum seal valve. FIG. 11A and 11B are explanatory diagrams for explaining the effect of a connection mechanism. 11A and 11B are explanatory diagrams for explaining the effect of a connection mechanism. FIG. 4A and 4B are explanatory diagrams of the open and closed states of the opening and closing mechanism, in which (A) shows the open state (unsealed state) and (B) shows the closed state (sealed state). This is a modified example, which corresponds to FIG.

(Electron microscope 100)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present disclosure will now be described with reference to the accompanying drawings. Fig. 1 is a schematic diagram of an electron microscope 100 including a vacuum seal valve 1 according to an embodiment.

As shown in FIG. 1, the electron microscope 100 includes an electron gun 101, an electron beam control mechanism 102 including a lens mechanism for converging the electron beam EB emitted from the electron gun 101 onto a predetermined portion of the sample W and a scanning mechanism for scanning the electron beam EB, and a lens barrel 103 that houses the electron gun 101 and the electron beam control mechanism 102.

The electron microscope 100 is a scanning electron microscope (SEM) that detects secondary electrons and the like generated by irradiating a sample W with an electron beam EB emitted from an electron gun 101, and displays a sample image based on this detection signal in synchronization with two-dimensional scanning of the electron beam EB on the sample W. The configuration of the present disclosure is not limited to application to the electron microscope 100, but is also suitable for a transmission electron microscope (TEM) that irradiates the sample W with an electron beam EB and magnifies and observes the electrons that have passed through it, an electric wire drawing device, an electron beam exposure device, and the like. Also, an ion gun may be used instead of the electron gun 101 to irradiate an ion beam.

The column 103 has therein an electron gun chamber 104 that houses the electron gun 101, a control mechanism chamber 105 that houses the electron beam control mechanism 102, and a partition wall 106 that separates them. The partition wall 106 has an opening 107 that connects the electron gun chamber 104 and the control mechanism chamber 105. Due to the characteristics of the electron microscope 100, the electron gun chamber 104 is evacuated to a vacuum (ultra-high vacuum of 10 ^-5 Pa or less, or extremely high vacuum of 10 ^-8 Pa or less) by a vacuum exhaust mechanism 108A. Similarly, the control mechanism chamber 105 is evacuated to a vacuum by a vacuum exhaust mechanism 108B.

The electron microscope 100 is equipped with a vacuum seal valve 1 as a mechanism for sealing/unsealing (hereinafter referred to as opening and closing) the opening 107. The vacuum seal valve 1 is supported by passing through a through hole 109 provided in the side wall 103a of the microscope tube 103, which is approximately perpendicular to the partition wall 106. Since it takes time to evacuate the electron microscope 100, when repairing the electron gun 101 or replacing the sample W, the vacuum seal valve 1 is used to maintain the electron gun chamber 104 or the control mechanism chamber 105 at a vacuum. In addition, when transporting the electron microscope 100, the opening 107 is sealed with the vacuum seal valve 1.

(Vacuum sealing valve 1)
The vacuum seal valve 1 will be described in detail with reference to Figures 2 to 4. Figure 2 is a perspective view of the vacuum seal valve 1. Figure 3 is a side view of the vacuum seal valve 1. Figure 4 is a vertical cross-sectional view of the vacuum seal valve 1. In Figure 3, some components are omitted for ease of explanation.

As shown in Figures 2 to 4, the vacuum sealing valve 1 is provided with an opening/closing mechanism 2 at the tip that opens and closes the opening 107. The opening/closing mechanism 2 is composed of a moving side mechanism 7 and a fixed side mechanism 8 that is fixed to the partition wall 106. The moving side mechanism 7 of the opening/closing mechanism 2 is connected to a bellows 4 via a connection mechanism 3, and the bellows 4 is connected to an actuator 6 via a fixed part 5.

The actuator 6 is the driving source of the vacuum sealing valve 1. When the actuator 6 moves back and forth approximately parallel to the partition wall 106, this movement is transmitted to the opening and closing mechanism 2, which converts the back and forth movement of the actuator 6 into a motion for opening and closing the opening 107, thereby opening and closing the opening 107.

In this embodiment, a double-acting air cylinder is used for the actuator 6. A retractable single-acting air cylinder may be used, and when the electron gun 101 is not in use, the cylinder is maintained in a forward position by the bias of a compression spring or the like to keep the opening/closing mechanism 2 in a closed position, and only when the electron gun 101 is in use, the cylinder is moved backwards by air pressure to open the opening/closing mechanism 2. The bias of the compression spring makes it easy to maintain the opening/closing mechanism 2 in a closed position. The actuator 6 is not limited to this, and any known driving mechanism may be used.

As shown in FIG. 4, the bellows 4 is arranged to cover the periphery of the transmission shaft 41 arranged inside. The transmission shaft 41 is connected to the actuator 6 via a connection shaft 42. An end of the bellows 4 is fixed to the surface of the fixed part 5, and the internal space of the bellows 4 communicates with the internal space 51 provided in the fixed part 5. In this communicated internal space, the transmission shaft 41 moves forward and backward integrally with the actuator 6. By using the bellows 4, the transmission shaft 41 can be moved forward and backward by obtaining power from the actuator 6 located outside the electron gun chamber 104 (atmospheric side) while maintaining the vacuum atmosphere of the electron gun chamber 104.

The transmission shaft 41 is connected to the main shaft 71 that constitutes the moving mechanism 7 of the opening/closing mechanism 2 via the connection mechanism 3, and the forward and backward movement of the actuator 6 is transmitted to the opening/closing mechanism 2 as they move together.

(Connection mechanism 3)
The connection mechanism 3 that connects the transmission shaft 41 and the main shaft 71 will be described in detail. Fig. 5 is an exploded perspective view of the connection mechanism 3. In the description, the direction in which the transmission shaft 41 is arranged is defined as the rear, and the direction in which the main shaft 71 is arranged is defined as the front.

As shown in FIG. 5, the connection mechanism 3 includes a first connection member 31, a second connection member 32, and a headless bolt 34 in addition to the transmission shaft 41 and main shaft 71 that are connected.

From the front, the main shaft 71, the second connecting member 32, the first connecting member 31, and the transmission shaft 41 are arranged in this order with their axes aligned in the front-to-rear direction.

The transmission shaft 41 is a long, thin rod-shaped body, and a disk-shaped first flange portion 41a is provided on the front side where it is connected to the main shaft 71. The bellows 4 is welded to the rear surface of the first flange portion 41a (see Figure 4).

A column 41b protrudes forward from the first flange 41a, and a disk-shaped second flange 41c is provided at the tip of the column 41b. The second flange 41c has two through holes 41d that pass through it, and the bolts 33 are inserted through them and screwed into the screw holes 31b provided in the first connection member 31, thereby fastening the transmission shaft 41 to the first connection member 31.

A circular recess 41e is provided in the center of the front surface of the second flange portion 41c, and the circular protrusion 31a protruding from the center of the rear surface of the first connecting member 31 engages with this to assist in fastening.

The first connecting member 31, which has a cylindrical shape, has a female threaded portion 31d provided as a screw hole in the center of the front surface. The male threaded portion 32a protruding from the center of the back surface of the second connecting member 32 screws into this female threaded portion 31d. The female threaded portion 31d and the male threaded portion 32a are used to adjust the position of the main shaft 71 in the front-rear direction, and the position of the main shaft 71 can be adjusted in the front-rear direction by the thread length of the male threaded portion 32a.

After the second connection member 32 is screwed onto the first connection member 31 and the front-rear positioning adjustment for the main shaft 71 is performed, the headless bolt 34 is inserted into the insertion hole 32c provided in the second connection member 32 and screwed into the screw hole 31c provided in the first connection member 31. As a result, the tip end 34a of the headless bolt 34 is fixed to the first connection member 31, and the rear end 34b protrudes from the surface of the first connection member 31 and is positioned within the insertion hole 32c of the second connection member 32. The size of the headless bolt 34, more specifically the rear end 34b, is set so that there is a slight gap between the inner wall of the insertion hole 32c and the inner wall of the insertion hole 32c.

The insertion hole 32c is formed at a position that communicates with the screw hole 31c, and the second connection member 32 has multiple insertion holes 32c on the same circle centered on the screw-engagement axis of the female screw portion 31d and the male screw portion 32a.

On the other hand, a flange portion 71a is also formed at the rear end of the main shaft 71, and the bolt 35 is inserted through two insertion holes 71b formed in the flange portion 71a and screwed into the screw hole 32b provided on the front surface of the second connection member 32, thereby fastening the main shaft 71 to the second connection member 32. In this way, the main shaft 71 and the transmission shaft 41 are connected via the connection mechanism 3.

(Function and effect of connection mechanism 3)
The connection mechanism 3 having such a configuration has three functions and effects. The first function is, as described above, adjustment of the arrangement of the main shaft 71.

As will be described in detail later, the main shaft 71 is provided with a through hole 71c for passing the electron beam EB, and in order to ensure a path (beam path) for the electron beam EB when the opening/closing mechanism 2 is in the open state, this through hole 71c must be positioned on approximately the same vertical line as the opening 107. Such highly accurate positioning requirements can be met by adjusting the connection length using the connection mechanism 3. Since the connection length is adjusted by screwing, the male and female threads may be reversed.

The insertion holes 32c are provided in two opposing positions, and either of the insertion holes 32c may be used when screwing in the headless bolt 34 after length adjustment. Since the second connecting member 32 is configured so that it can be prevented from rotating by the headless bolt 34 every half rotation, the connection length can be finely adjusted in increments of half a thread of the male screw portion 32a.

The second is to absorb damage caused by the circumferential movement of the bellows 4. The headless bolt 34 protrudes from the first connecting member 31 and is placed in the insertion hole 32c. The diameter of the insertion hole 32c is slightly larger than the diameter of the headless bolt 34, and since no locking nut or the like is used on the headless bolt 34, the second connecting member 32 can rotate by this difference in diameter. In other words, the main shaft 71 and the transmission shaft 41 can rotate slightly in the circumferential direction even after their lengths have been adjusted and they are connected.

The bellows 4 is a type of spring structure made by welding metal plates, and it contracts to follow the axial movement of the fixed transmission shaft 41. However, it cannot move at all in the circumferential direction, and even the slightest rotational movement of the transmission shaft 41 fixed to the bellows 4 places excessive stress on the bellows 4, causing it to break. For example, even if a slight twist in the circumferential direction occurs during the opening and closing movement of the opening and closing mechanism 2 and is transmitted to the main shaft 71 as rotational movement, the second connecting member 32 rotates to absorb this, reducing the rotational load on the bellows 4.

As in the conventional configuration, if the position is adjusted by screwing in the screws and then the main shaft and transmission shaft are completely fixed using a locking nut or the like, even the slightest rotation of the opening and closing mechanism is directly transmitted to the transmission shaft, causing the problem that the bellows connected to the transmission shaft will be destroyed by the rotational load. On the other hand, if the position is only adjusted by screwing in and there is no rotation prevention at all, the screwing will loosen due to sliding when opening and closing, causing a problem that the connection length and connection angle will change.

In this embodiment, the headless bolt 34 is used to prevent rotation, while a gap is provided in the insertion hole 32c through which the headless bolt 34 is inserted, leaving a small amount of room for the first connection member 31 to rotate. This allows the rotation of the main shaft 71 to be absorbed by the amount of this gap, and the rotation transmitted to the bellows 4 is reduced. By configuring the connection mechanism 3 as described above, damage caused by the circumferential movement of the bellows 4 is absorbed. Furthermore, the rotation of the main shaft 71 can suppress imbalances in the sealing force.

In this embodiment, the second connecting member 32 is made of steel such as stainless steel, and the first connecting member 31 is made of a metal such as beryllium copper that is softer than the components of the second connecting member 32. By using different metals, friction on the sliding surfaces of the screwed parts is reduced, making it easier for the two to slide (rotate). In addition, by making the female threaded part 31d out of a metal softer than the male threaded part 32a, the female threaded part 31d is scraped off during slippage, reducing friction during slippage. This makes it easier for the second connecting member 32 and the first connecting member 31 to rotate, further reducing the rotational load on the bellows 4.

The third effect is the correction of the circumferential deviation of the main shaft 71 from the normal position that occurs when the fixed part 5 is fixed to the lens barrel 103. This will be explained using Figures 6 and 7. Figure 6 shows the fastened state of the fixed part 5 and the lens barrel 103, as seen from the direction of arrow A in Figure 3. It is a schematic diagram showing the relative arrangement of the lens barrel 103 and the fixed part 5, and the fixing bolt is omitted. Figures 6(A) and 6(B) show the state in which the fixed part 5 is fixed to the lens barrel 103 in the normal position. Figure 6(C) shows the state in which the fixed part 5 is fastened to the lens barrel 103 at a tilt counterclockwise from the normal position. Figure 6(D) shows the state in which the fixed part 5 is fastened to the lens barrel 103 at a tilt clockwise from the normal position.

The vacuum sealing valve 1 is fixed to the flange of the through hole 109 by the fixing part 5 (see FIG. 3). As shown in FIG. 6, the lens barrel 103 has six screw holes 103b arranged at equal angles in a circular ring shape for fastening the fixing part 5. The fixing part 5 to be fixed has six screw insertion holes 52 arranged at equal intervals in a circular ring shape corresponding to the screw holes 103b. However, in order to absorb the formation error of the screw holes 103b and to reliably fasten the fixing part 5, the hole diameter of the screw insertion holes 52 needs to be larger than the diameter of the screw holes 103b, and the fixing part 5 may be installed at a slight circumferential tilt from the correct position by the difference in diameter.

As shown in FIG. 6(C), the fixing part 5 may be installed tilted counterclockwise by a maximum angle of -α around the mounting center O of the fixing part 5 from the normal position. Also, as shown in FIG. 6(D), the fixing part 5 may be installed tilted clockwise by a maximum angle of +α around the mounting center O. Here, the angle ±α is the mounting play angle calculated from the difference in diameter between the screw hole 103b and the screw insertion hole 52.

Even if the fixing part 5 is installed at an angle of α, the connecting mechanism 3 rotates so that the connected main shaft 71 is horizontal, which is the correct position, and remains so. In this way, the headless bolt 34 and the insertion hole 32c not only serve to stop the rotation of the second connecting member 32 after the length adjustment, but also serve to fine-tune the circumferential direction. The arrangement and diameter of the headless bolt 34 and the insertion hole 32c determine the relative rotation angle between the main shaft 71 and the transmission shaft 41. It is preferable that this rotation angle be equal to or greater than 2α.

In the case of a conventional configuration in which there is no connection mechanism 3 and the main shaft and the transmission shaft are completely fixed, if the vacuum sealing valve is attached to the lens barrel at an angle α, the main shaft will also be tilted at an angle α from the horizontal position, and the valve body will seal the opening at an angle α.

The difference between this embodiment and the conventional configuration will be explained using FIG. 7. FIG. 7 is a view of the opening/closing mechanism 2 as seen from the front. It shows the state in which the fixing part 5 is fixed in the correct position. The O-ring 76 is a sealant that seals the opening 107. The O-ring 176 shown by the two-dot chain imaginary line is a sealant in a conventional configuration without the connection mechanism 3, shown for comparison, and is shown in a state in which it is attached at an angle α around the attachment center O of the fixing part.

In a conventional vacuum sealing valve in which the opening/closing mechanism and the actuator are completely integrated in the circumferential direction, if the opening/closing mechanism is attached to the housing at an angle α in the circumferential direction, the opening/closing mechanism will also be tilted at the angle α in the circumferential direction. In other words, the O-ring 176 that seals the opening will also be tilted at the angle α around the attachment center. The amount of crushing of the O-ring 176 will decrease by the height difference H of the O-ring 176 in this tilted state, and the sealing force of the O-ring 176 will decrease.

For example, in this embodiment, the angle α is 1.2 degrees, which results in a height difference H of 0.2 mm above the opening 107. In other words, if the fixed part 5 is attached to the lens barrel 103 at an angle of 1.2 degrees around the attachment center O, the main shaft 71 also tilts 1.2 degrees around the attachment center O, and the amount of crushing of the sealant is reduced by up to 0.2 mm in some places. The amount of crushing of the sealant sealing the opening 107 is about 0.5 mm, resulting in a loss of sealing force of about 40%. To hermetically seal the opening 107, the sealant needs to seal the opening 107 horizontally, and it is important to correct the circumferential misalignment using the connection mechanism 3.

Returning to Figure 4, we will now explain the connection part 43, which is the connection mechanism between the transmission shaft 41 and the connection shaft 42. The rear end of the transmission shaft 41 is provided with a male thread part 41f. The front end of the connection shaft 42, which is connected to this, is provided with a female thread part 42a, and the two are screwed together to connect the transmission shaft 41 and the connection shaft 42. Due to the play, the structure is such that rotation is not transmitted to the bellows. This prevents strain on the bellows 4 during assembly.

(Opening and closing mechanism 2)
The opening/closing mechanism 2 will be described in detail with reference to Fig. 8 and Fig. 9. Fig. 8 is a cross-sectional view of the opening/closing mechanism 2 in an open state. Fig. 9 is an explanatory diagram for explaining the opening and closing state of the opening 107 by the opening/closing mechanism 2, where (A) shows the open state and (B) shows the closed state.

As described above, the opening/closing mechanism 2 is composed of a fixed side mechanism 8 that is fixed to the partition wall 106, and a movable side mechanism 7 that moves in accordance with the forward and backward movement of the actuator 6.

The fixed side mechanism 8 includes a support member 81, upper rollers 82 and 83, and a lower roller 84. The movable side mechanism 7 includes a main shaft 71, an auxiliary member 72, a spring 73, a pair of links 74, a valve body 75, an O-ring 76, and a bolt 77.

The support members 81 are a pair of L-shaped brackets that face each other in a position that does not impede the movement of the electron beam EB or the moving mechanism 7, are fixed to the partition wall 106 on a horizontal plane, and rotatably support the upper rollers 82, 83 and the lower roller 84 on a vertical plane (see FIG. 2). For the sake of explanation, one of the support members 81, which is located on the front side of the paper, is omitted in FIG. 9.

The upper rollers 82, 83 are rotating bodies that suppress deformation of the main shaft 71, that is, suppress the main shaft 71 from bending upward due to the reaction force generated by pressing the valve body 75 against the opening 107. They are arranged in parallel to the forward and backward movement of the main shaft 71, and their rotation axes are perpendicular to the forward and backward movement of the main shaft 71, but since they do not function as conveyors to guide the forward and backward movement of the main shaft 71, it is preferable that they approach the main shaft 71 in the open state but do not come into contact with it.

The upper rollers 82, 83 are arranged above the main shaft 71, facing the opening 107 below with the main shaft 71 in between in the vertical direction. In addition, with respect to the forward and backward direction of the main shaft 71 (front-rear direction), the upper roller 83 is arranged at the tip side of the main shaft 71, and the upper roller 82 is arranged at the base end side of the main shaft 71, with the opening 107 as the reference. By arranging the two upper rollers 82, 83 on either side of the opening 107, deformation of the main shaft 71 can be stably and firmly suppressed.

The valve body 75 has a generally rectangular parallelepiped shape and is linked and connected to the main shaft 71 by a pair of links 74. It moves up and down as the main shaft 71 moves back and forth, thereby directly opening and closing the opening 107.

The spring 73 is an elastic body that biases the valve body 75 in a direction that maintains the valve body 75 in an open state. The forward bias of the spring 73 is converted to an upward bias by the link 74, and in the open state, the valve body 75 is held apart from the partition wall 106.

The lower roller 84 is disposed in front of the valve body 75, facing the upper roller 83 across the main shaft 71. An inclined surface 75b is formed on the front surface of the valve body 75, and when the main shaft 71 moves back and forth, the lower roller 84 abuts against the inclined surface 75b, moving the valve body 75 up and down.

The inclined surface 75b is very steep. After the valve body 75 abuts against the lower roller 84, it moves in the direction of the gradient of the inclined surface 75b, so the gradient is made large to move the valve body 75 approximately vertically. If the inclined surface 75b has a gentle gradient, the amount of movement of the valve body 75 in the forward and backward directions increases as well as the vertical movement of the valve body 75 from when the O-ring 76 comes into contact with the sealing surface until it is completely sealed, and the O-ring 76 slides against the partition wall 106 from when the O-ring 76 comes into contact with the sealing surface, which is the partition wall 106, until it is completely sealed. In a high vacuum atmosphere, no sliding force works, and a large load is applied to the O-ring 76 due to twisting and high friction sliding. In order to reduce damage to the O-ring 76 and improve its durability, the inclined surface 75b is steep. Specifically, an inclination angle of 70 degrees or more is preferable.

The auxiliary member 72 is an auxiliary member for holding the spring 73, and is formed with a deep recess 72a for holding the spring 73. The auxiliary member 72 is disposed on the back surface of the valve body 75 and is fixed to the bottom surface of the main shaft 71 by bolts 77 so that the spring 73 can efficiently bias the valve body 75. It is also possible to have a configuration in which the spring 73 is held directly by the main shaft 71 without using the auxiliary member 72.

The O-ring 76 is a sealing member for airtightly sealing the opening 107. A dovetail groove 75a is provided in an annular shape on the underside of the valve body 75, and the O-ring 76 fits into this groove, thereby attaching it to the underside of the valve body 75.

The valve body 75 is connected to the link 74 at a thin-walled portion 75d with its side cut away so that there is no step between the valve body 75 and the link 74 and the link 74 is connected smoothly. This reduces the width of the moving mechanism 7.

The valve body 75 and the main shaft 71 are provided with through holes 75c, 71c, respectively, for passing the electron beam EB. When the opening/closing mechanism 2 is assembled, the through holes 75c, 71c are configured to communicate with each other. As described above, the connection mechanism 3 allows fine adjustment of the position of the main shaft 71 in the front-to-rear direction, and when the opening/closing mechanism 2 is in the open state, the position is adjusted so that the opening 107 and the through holes 75c, 71c are aligned in a straight line in the vertical direction. This ensures a path for the electron beam EB.

Of course, the valve body 75 and the main shaft 71 are made of non-magnetic material so as not to adversely affect the electron beam EB. By providing holes in the valve body 75 and the main shaft 71 that serve as a path for the electron beam EB, the valve body 75 can be positioned above the opening 107 even in the open state, reducing the amount of forward and backward movement of the main shaft 71 required to open and close the opening 107, minimizing the generation of particles due to metal sliding.

In this embodiment, the link mechanism that displaceably connects the valve body 75 and the main shaft 71 is composed of a pair of links 74. The pair of links 74 face each other on both sides of the valve body 75, linking and connecting the valve body 75 and the main shaft 71. Therefore, the rotation axis 74a of the link 74 and the valve body 75 is horizontal (see FIG. 8. The rotation axis 74a extends in the depth direction of the paper). The valve body 75 is supported so that it can rotate up and down around this rotation axis 74a. By configuring the link mechanism in this way, the inclination of the valve body 75 in the front-rear direction that occurs when the fixed part 5 is fixed to the telescope tube 103 is corrected. The inclination of the valve body 75 in the front-rear direction refers to the inclination from the horizontal with the horizontal axis that is perpendicular to the forward and backward direction of the main shaft 71 as the central axis.

For example, if the mounting surface of the fixed part 5 formed on the side wall 103a is inclined at an angle β from the vertical, the fixed part 5 is also inclined at an angle β from the vertical, so that the main shaft 71 is in a state in which the front neck is lowered (or raised) by the angle β. Therefore, in the mounted state, the inclination of the valve body in the front-rear direction is also angle β. If the valve body is supported by a link mechanism using four links (two pairs of links), the valve body cannot rotate, so the inclined state cannot be eliminated, and the opening is sealed in the inclined state. In contrast, in this embodiment, the valve body 75 is supported rotatably on the rotating shaft 74a by a pair of links 74, so that even if it is inclined by angle β in the mounted state, the force that moves the inclined surface 75b in the vertical direction causes the valve body 75 to rotate on the rotating shaft 74a, lowering (or raising) the rear neck and making it horizontal, thereby uniformly sealing the opening 107. As mentioned above, in this embodiment, if the main shaft is inclined by 1.2 degrees, the sealing force is lost by about 40%, which has a large impact. To airtightly seal the opening 107, the valve body 75 with the O-ring 76 attached must seal the opening 107 horizontally. Also, slight play when attaching the fixed part 5 and unevenness on the fixed surface can cause the valve body 75 to tilt. By using only a pair of links 74 as a link mechanism to rotatably support the valve body 75, such individual differences and errors can be absorbed and the forward/backward tilt of the valve body 75 can be corrected.

In the valve body 75, the inclination about two horizontal axes (the horizontal axis in the forward and backward direction of the main shaft 71 and the horizontal axis perpendicular to it) is corrected, so that the O-ring 76 seals the opening 107 in a horizontal state, and the opening 107 is airtightly sealed.

In addition, the surface of the partition wall 106 around the opening 107, which serves as the sealing surface for the O-ring 76, is also mirror-finished to improve sealing performance.

Furthermore, as shown in Figures 8 and 9, the partition wall 106 around the opening 107 is configured as a slightly higher step 106a. This is to reduce the possibility of particles falling into the sealed area even if they are generated by the sliding of metal parts due to the movement of the opening/closing mechanism 2. Furthermore, particles that fall from the step 106a are less likely to climb up onto the step 106a again, i.e., the sealed area, so a decrease in sealing performance can be suppressed.

(Action and effect of opening/closing mechanism 2)
When the opening/closing mechanism 2 is in the open state, the valve body 75 is biased by the spring 73 and is disposed away from the partition wall 106 (see FIG. 9A). When the main shaft 71 moves forward and the inclined surface 75b comes into contact with the lower roller 84, the valve body 75 moves downward to seal the opening 107 (see FIG. 9B).

The forward motion of the main shaft 71 is converted by the lower roller 84 into the downward movement of the valve body 75, and the valve body 75 moves downward, causing the O-ring 76 to press against the partition wall 106, but receives an upward reaction force from the partition wall 106 (arrow DR1 in FIG. 9B). The upper rollers 82, 83 come into contact with the main shaft 71, which tries to warp in response to this upward reaction force, and suppress deformation of the main shaft 71 (arrows DR2, DR3 in FIG. 9B).
In the conventional configuration, without the upper rollers 82 and 83, the main shaft would bend into an arch shape due to the reaction force from the partition wall even if the valve body was moved to the opening. This caused the O-ring to be pressed at an angle, making it impossible to obtain a uniform pressing pressure and maintaining a high sealing effect.

In contrast, in this embodiment, by arranging the upper rollers 82, 83 on the top of the main shaft 71, the upper rollers 82, 83 receive the reaction force and prevent the main shaft 71 from warping, so that the O-ring 76 obtains a uniform pressing pressure and can airtightly seal the opening 107.

Furthermore, the pressure on the valve body 75 is prevented from escaping in the opposite direction to the opening 107 as a reaction force, which would otherwise reduce the pressure on the valve body 75, and the forward motion of the main shaft 71 can be converted into the pressure on the valve body 75 with high efficiency. As a result, the valve body 75 airtightly seals the opening 107.

The amount of movement of the main shaft 71 in the forward and backward directions to open and close the opening 107 is also small, so metal sliding can be reduced accordingly, and particle generation can be reduced.

In addition, in the conventional vacuum sealing valve, the opening and closing mechanism is too large to be removed from the vacuum chamber, or both the lens barrel and the vacuum sealing valve must be disassembled to remove the vacuum sealing valve, making it difficult to replace the O-ring. In addition, in order to maintain a high degree of vacuum in the vacuum chamber, it is preferable that the through-hole of the lens barrel through which the drive source outside the lens barrel and the sealing valve inside the lens barrel are inserted is small. In this embodiment, the upper rollers 82, 83 and the lower roller 84 are fixed to the partition wall 106 as the fixed side mechanism 8, and the moving side mechanism 7 is compactly configured so that the moving side mechanism 7 can be removed from the through-hole 109. This makes it easy to repair in the event of a breakdown and to replace the O-ring 76. In particular, in the electron microscope 100, which requires a high degree of vacuum, it is important that the O-ring 76, which is easily deteriorated, can be easily replaced in order to hermetically seal the opening 107.

(Modification)
The configuration of the present disclosure is not limited to the above embodiment. A modified example is shown in FIG. 10. Components having equivalent configurations are given the same reference numerals and will not be described. As shown in FIG. 10, the first connecting member 31 is provided with a male screw portion 131d protruding from the center of the front surface thereof, and this is screwed into a female screw portion 132a provided in the center of the back surface of the second connecting member 32, thereby connecting the first connecting member 31 and the second connecting member 32 in an adjustable connection length. In this way, the male-female configuration of the screw connection between the first connecting member 31 and the second connecting member 32 may be reversed.

The engaging member that engages successively with the first connecting member 31 and the second connecting member 32 is not limited to the headless bolt 34. As shown in FIG. 10, a pin 134 or a screw may be used. The pin 134 is a cylindrical body, and an engaging hole 132c is formed as a through hole in the second connecting member 32 corresponding to the shape of the pin 134. The first connecting member 31 has an insertion hole 131c formed at a position that can be in series with the engaging hole 132c.

After the second connection member 32 is screwed to the first connection member 31 and the front-rear positioning adjustment for the main shaft 71 is performed, the pin 134 is inserted into the engagement hole 132c from the front side and engaged, and the tip 134a protrudes from the back side of the second connection member 32 and passes through the insertion hole 131c. The inner diameter of the insertion hole 131c is set to be slightly larger than the outer diameter of the tip 134a of the pin 134, so that the tip 134a is positioned in the insertion hole 131c with some clearance. The insertion hole 131c is a through hole, and when removing the pin 134, it is pushed in as it is and removed from the back side of the first connection member 31.

Just as the headless bolt 34 is engaged with the first connecting member 31 and a portion of it protrudes into the insertion hole 32c of the second connecting member 32, the pin 134 is engaged with the second connecting member 32 and a portion of it protrudes into the insertion hole 131c of the first connecting member 31. In this way, the engagement configuration may be reversed. When engaged with the first connecting member 31 or the second connecting member 32, the engaging member is arranged so that a portion of it protrudes into the hole of the other connecting member, and its maximum outer diameter is made smaller than the inner diameter of the hole of the other connecting member, so that there is some gap with the inner wall of the hole.

The engagement hole 132c and insertion hole 131c in which the pin 134 is placed are provided on a circle of equal diameter centered on the axis of the screw engagement so that they can be arranged in series. The engagement holes 132c are provided in two locations facing each other around the screw engagement axis of the male screw portion 131d and the female screw portion 132a, and the insertion holes 131c are provided in six locations at unequal angles to avoid the screw hole 31b. In this way, if the holes in which the engagement members are placed are provided at multiple locations at equal or unequal intervals centered on the axis of the screw engagement, the position of the main shaft 71 can be adjusted more precisely, which is preferable.

The above describes the preferred embodiment of the present invention, but modifications are possible based on the knowledge of those skilled in the art, and such modifications are within the scope of the present invention.

1: Vacuum sealing valve 3: Connection mechanism 6: Actuator 31: First connection member 31c: Screw hole 32: Second connection member 32: Second connection member 32c: Insertion hole 34: Headless bolt 34a: Tip portion 41: Transmission shaft 41f: Male thread portion 42: Connection shaft 43: Connection portion 71: Main shaft 75: Valve body 107: Opening

Claims (4)

A connection mechanism for a vacuum seal valve that connects a first shaft member that is connected to a drive mechanism and driven by the drive mechanism, and a second shaft member that is connected to a valve body that seals an opening and transmits the drive of the first shaft member,
a first connecting member fixed to an end of the first shaft member and having a first engagement hole formed at an end facing the second shaft member;
a second connecting member fixed to an end of the second shaft member, threadably engaged with the first connecting member, and having a second engaging hole formed in an end facing the first shaft member at a position that allows the second engaging hole to be aligned in series with the first engaging hole;
an engaging member that engages with one of the first engaging hole and the second engaging hole and has a protruding portion that protrudes into the other engaging hole in an engaged state;
Equipped with
The protrusion has an outer diameter smaller than an inner diameter of the other engagement hole.
A connection mechanism for a vacuum seal valve. the one engagement hole that engages with the engagement member is a screw hole,
The engaging member is a headless bolt or a bolt having a head diameter smaller than the inner diameter of the other engaging hole.
2. The vacuum seal valve connection mechanism according to claim 1 . At least one of the first engagement hole and the second engagement hole is
A plurality of the threaded joints are provided at equal or unequal intervals on a concentric circle centered on an axis of threaded engagement between the first connection member and the second connection member.
3. The connection mechanism for a vacuum seal valve according to claim 1 or 2. The first shaft member is connected to the drive mechanism via a connecting mechanism,
The first shaft member is also connected to the connecting mechanism by threaded engagement.
4. The connection mechanism for a vacuum seal valve according to claim 1.