JPS5846521Y2 - Shutter devices such as electron microscopes - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a shutter device that utilizes a lens magnetic field.

A conventional example of a shutter device using such a lens magnetic field is shown in FIG.

In the figure, reference numeral 1 denotes a substrate, and as shown in FIG. 2, the substrate 1 is inserted between lens pole pieces 2a and 2b and fixed to a lens yoke or the like.

An electron beam passage hole 3 is provided on the substrate, and its axis is aligned with the lens axis (optical axis).

Two terminal plates 4 a and 4 b are fixed on the substrate 1 and electrically insulated from the substrate 1, and are connected to both terminals of a DC power source 6 via a switch 5, respectively.

Reference numeral 7 denotes a plate-shaped or band-shaped conductive foil, which is bent into a U-shape and has U-shaped bent portions 8a and 8b formed on both end surfaces 7a and 7b to have elasticity. and both end surfaces 7a and 7b are connected to the terminal plate 4.
a and 4 b, respectively.

A shutter member 9 made of heat-resistant metal is attached to the conductive foil 7 at a location corresponding to the electron beam passage hole 3 of the substrate 1.

10 is a stopper.

However, now, if the direction of the lens magnetic field is the same as the traveling direction of the electron beam E, when the switch 5 is closed, a constant DC current flows from the power supply 6 to the conductive foil 7, and according to Fleming's left hand rule, the conductive foil 7 A force in the right direction in the figure acts on the surface 7C to which the shutter member 9 is attached, and the conductive foil moves.

Therefore, since the shutter member 9 closes the electron beam passage hole 3 due to the movement of the conductive foil 7, the electron beam E is cut.

In order to increase the stroke of the shutter member 9, a U-shaped bent portion 8 is formed in the middle of the conductive foil 7 as described above.
In the structure in which the conductive foils 7a and 8b are provided, when a current is supplied to the conductive foil 7, the shutter member 9 vibrates, making it impossible to completely block the electron beam.

In other words, when the conductive foil 7 is energized, the surface 7C moves to the right, and the bottom a portions of the bent portions 8 a and 8 b bend in the same direction, so that a drag is exerted on the new bent portions 8 a and 8 b. arise.

The drag force gradually increases in accordance with the amount of movement of the surface 7C of the conductive foil 7, and finally becomes larger than the force on the surface 7C, causing the surface 7C to move in the opposite direction (to the left).

This movement of the surface 7C to the left reduces the drag, and the surface 7C moves to the right again.

Since this phenomenon is repeated thereafter, the shutter member 9 to which the surface 7C is fixed vibrates, resulting in a state in which the electron beam cannot be completely blocked.

The present invention is aimed at solving such inconveniences, and will be explained below based on an embodiment shown in FIG.

Note that the same numbers as in FIGS. 1 and 2 indicate the same components.

That is, in the present invention, the conductive foil 11 attached to the substrate 1 is bent into a rectangular shape such that both end surfaces 11a and 11b overlap each other with a distance between them to obtain large elasticity (bending). Both end faces 11 of
A shutter member 9 is fixed to the surface 11C facing a and llb.

Further, the respective tips of the end surfaces 11a and 11b are fixed to the terminal plates 4a and 4b, respectively.

With such a configuration, the stroke of the shutter member 9 can be controlled without causing vibration of the shutter member 9 compared to a conventional structure in which a U-shaped bent portion is formed in the middle of the conductive foil. It can be long.

That is, in the present invention, when the shutter plate 9 is moved to the right in FIG. 3 through the conductive foil 11, the end surfaces 11a and 11b of the conductive foil 11 are also bent in the same direction, so that a drag force is generated in these parts. .

At this time, the length of the end surface 11a (11b) of the conductive foil is very long (more than twice) than the length of the surface 8al (8bl) of the bent portion 8a (8b) shown in FIG. The drag force of the present invention is much smaller than that of the conventional method.

Therefore, the drag force generated at the end surfaces 11a and llb of the conductive foil in the present invention is also reduced compared to the structure shown in FIG.
When the conductive foil 11 is energized, the shutter member 9 does not vibrate, and the electron beam can be reliably cut, which has a great practical effect.

On the other hand, when attaching the shutter member 9 to the conductive foil 11, three protrusions 12 a , 12 b , and 12 C are formed on the shutter member 9 as shown in FIG.
Each of the protrusions 12 a , 12 b , 12 C is connected to the fourth
If the conductive foil 11 is bent and attached to the surface 11C as shown in FIG. b, the contact area between the conductive foil 11C and the shutter member 9 can be reduced.

Therefore, even if the temperature of the shutter member 9 increases due to electron beam irradiation, the temperature of the conductive foil can be prevented from increasing.

[Brief explanation of the drawing]

Figures 1 and 2 are views showing a conventional example, Figure 3 is a perspective view showing an embodiment of the present invention, and Figures 4a and b are perspective views of shutter members used in the present invention. be. In the figure 1: Substrate, 2a, 2b: Lens pole pieces,
3: electron beam passage hole, 4a and 4b: terminal plate, 5: switch, 6: DC power supply, 7 and 11: conductive foil, 9: shutter member.

Claims (1)

[Scope of utility model registration request] A device in which both ends of a foil-like conductor are fixedly placed in a magnetic field, and the conductor is moved using force generated by energizing the conductor to cut an electron beam, A shutter device for an electron microscope or the like, which comprises arranging the conductors near both ends so as to overlap each other while maintaining a distance from each other, and attaching a shutter member for cutting an electron beam to a portion of the conductor opposite to the overlapping portion near the both ends. .