JPH0240311Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a valve device for vacuum-blocking an electron beam passage in a high-vacuum device such as an electron microscope.

[Prior Art] Conventionally, in transmission electron microscopes and the like, in order to partially break the vacuum, for example, to replace the filament, only the electron gun part is separated from the rest, and a vacuum is created in a suitable place so that the vacuum can be broken. A shutoff valve is installed. The shutoff valve device can be equipped with a mechanism that moves the valve body from a direction perpendicular to the optical axis of the electron beam and presses the valve body against the valve seat, or a mechanism that moves the valve body from a direction perpendicular to the optical axis of the electron beam and presses the valve body against the valve seat. Many valves have a structure in which the valve body is pressed from a direction, and the pressure caused by the inclination causes the sealing material of the valve body to come into close contact with the valve seat.

[Problems to be solved by the invention] In general, the structure of conventional shutoff valve devices is such that the valve body slides against the valve seat. The sliding part is scraped and the metal powder falls into the electron beam path. If such metal powder adheres to, for example, the magnetic pole pieces of an electronic lens, it will greatly affect the distribution of magnetic flux in the lens, causing problems such as astigmatism. Furthermore, if the metal powder falls onto the fluorescent screen, it will interfere with observation of the electron microscope image projected thereon.
Furthermore, since the sealing material of the conventional shutoff valve is exposed to the electron beam path, it is exposed to X-rays generated when the electron beam collides with surrounding members, resulting in significant deterioration.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the conventional valve, an object of the present invention is to propose a novel shutoff valve device that does not generate shavings due to sliding and does not cause deterioration of the sealing material due to X-ray irradiation.

[Means for Solving the Problem] The present invention consists of two vacuum chambers that communicate with each other through a communication port, a valve seat provided at an angle with respect to the axis of the communication port, and a A valve body that moves in a right angle direction and has a sealing material on its end face, a closed state where the valve body is pressed against the valve seat, and an open state where the valve body is placed a certain distance away from the valve seat. a shielding body rotatably supported in the movement path of the valve body, arranged to cover the sealing material of the valve body when the valve is open, and made of a material having a large X-ray shielding effect. and a protruding member attached to the valve body to open the shield, and when the valve body is in the open state, the shield covers the sealing material of the valve body and protects it from irradiation with X-rays, etc. There is a feature in the shutoff valve device in a vacuum device with a structure like this.

[Embodiment] FIGS. 1 and 2 are sectional views showing an embodiment of the present invention, with FIG. 1 showing the shutoff valve in an open state and FIG. 2 showing a closed state. In the figure, numerals 1 and 2 communicate with each other via a communication port 3 in a vacuum chamber such as a lens barrel of a transmission electron microscope. A valve seat 4 inclined at an arbitrary angle with respect to the axis Z thereof is formed on the lower surface of the communication port 3 and has a mirror finish. Reference numeral 5 denotes a valve chamber that is connected to the vacuum chamber 2 at an angle, and a valve body 6 is disposed within the valve chamber. A vacuum sealing member 7 is attached to the end face of the valve body, and this sealing material closely contacts the valve seat 4 to seal against vacuum. Reference numeral 8 denotes a shaft for driving the valve body, which extends in a direction perpendicular to the surface of the valve seat, one end of which is fixed to the back surface of the valve body, and the other end of which passes through the valve chamber 5 and enters the cylinder 9. exposed. A piston 10 is fixed to the end of the shaft within this cylinder, and movement of the piston causes the valve body 6 to move via the shaft 9. Pipes 11 are installed at both ends of the cylinder 9.
Compressed gas introduction/discharge hole 12 connected to a and 11b
A and 12b are bored through which compressed gas is introduced and discharged. Cylinder 9 of the valve chamber 5
A bellows 13 is provided between the valve body 6 and a position close to the valve body 6.
is attached to allow movement of the valve body while preventing air from flowing into the vacuum chamber from the cylinder section.
Bearings 14a and 14b are attached to the valve body and function as protrusions for opening and closing a shield 16 rotatably supported inside the valve chamber 5. The shield is made of a heavy metal with high X-ray absorption efficiency, and is attached to the bearing part 17 by a coil spring or the like so that it is always in the closed state (the state shown in Fig. 1), and the side opposite to the bearing part is It is supported by a support 18 fixed to the valve body 6 to prevent the shield from coming into contact with the end face of the valve body 6.

In such a configuration, the state shown in FIG. 1 is a state in which the valve is open and vacuum chambers 1 and 2 are in communication;
When compressed gas is introduced into the right end of the cylinder 9 through the pipe 11a and the inlet 12a, the piston 10
moves diagonally upward in the figure, and the valve body 6 moves via the shaft 8 connected thereto. With this move,
The bearing 14a first abuts the shield 16 and pushes the shield open against the coil spring. As the piston moves further, the bearing 14b comes into contact with the shield, the shield becomes completely open, and finally the end face of the valve body 6 reaches the valve seat 4. This state is shown in FIG. 2, where the sealing material 7 of the valve body 6 is strongly pressed against the valve seat, and the communication port 3 is vacuum-blocked. Next, when opening the valve from this state, when compressed gas is introduced into the left end of the cylinder 9 through the pipe 11b and the inlet 12b, the piston 10 moves diagonally downward to the right in the figure. ,
The valve body 6 moves away from the valve seat in the same direction. As the movement progresses, both the bearings 14a and 14b are covered by the shield 16.
When separated from the shield, the shield is restored by the force of the coil spring and covers the sealing member 7 in the state shown in FIG.

In the above description, the mechanism for moving the valve body 6 is not limited to that shown in the drawings, and any mechanism such as a mechanical mechanism using a motor and gears can be used.

[Effect] As explained above, in this invention, the valve seat is aligned with the axis Z.
The valve body is mounted on the valve seat at a certain angle and is moved in a direction perpendicular to the valve seat, and a shield is opened and closed to protect the sealing material of the valve body in connection with the movement of the valve body. Since there are no sliding parts on the valve body and valve seat when the valve is opened and closed, no shavings are generated, which would adversely affect the performance of the lens or cause scratches on the fluorescent screen. There is no adverse effect on image observation caused by fallen shavings. Furthermore, since the sealing material is always protected by a shielding member with high X-ray absorption efficiency when the valve is open, deterioration of the sealing material due to X-ray irradiation is prevented.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing one embodiment of the present invention. 1, 2... Vacuum chamber, 3... Communication port, 4... Valve seat, 5... Valve chamber, 6... Valve body, 7... Vacuum sealing material, 8... Shaft, 9... Cylinder, 10 ……
Piston, 11a, 11b...Pipe, 12a,
12b... Compressed gas introduction/exhaust hole, 13... Bellows, 14a, 14b... Bearing, 16... Shielding body, 17... Bearing portion, 18... Support.

Claims (1)

[Scope of utility model registration request] two vacuum chambers communicating through a communication port; a valve seat provided at an angle with respect to the axis of the communication port;
A valve body that moves in a direction perpendicular to the face of the valve seat and has a sealing material on its end face, and a closed state where the valve body is pressed against the valve seat, and a position a certain distance away from the valve seat. a moving mechanism for creating a valve open state; It consists of a shield made of material and a protruding member attached to the valve body to open the shield, and when the valve body is in the open state, the shield covers the sealing material of the valve body. A shield valve device in a vacuum system that is protected from radiation such as radiation.