JPS61200642A - Manufacture of spherical grid for electron tube - Google Patents

Abstract

PURPOSE:To manufacture a spherical grid of a high accuracy for an electron tube, by forming a grid pattern made of exposed and developed metallic thin plate in a spherical surface, and engraving slits responding to the grid pattern. CONSTITUTION:A photoresisting layer 18 is pasted over a side of a thin element plate 17 of molybdenum, over which a pattern mask 19 drawn with a specific grid pattern is contacted closely, and exposed. Then the mask 19 is removed, and the layer 18 is developed. After that, a film 20 such as a plastic is spread over the developed layer 18. The plate 17 covered with the film 20 is placed between a pair of dies 21 and 22 with a specific curvature radius, and pressed. Then the film 20 is removed, and the plate 17 is formed into a numerous slits in a radial form by a chemical etching, remaining grid wire portions. Finally it is washed and finished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a spherical grid for an electron tube.

[Technical background of the invention and its problems] In an electron tube with a straight electron beam, such as a klystron or a traveling wave tube, one or more spherical grids aligned in front of a spherical cathode surface are used as a piercing electron gun. may be placed. This is a structure U as shown in FIGS. 3 to 5. In the figure, numeral 31 is a cathode with a spherical electron emitting surface, 32 is a heater, 33 is a cathode sleeve, 34
is the control grid, 35 is its flange, 36
37 is a shadow grid, 38 is a flange portion, and 39 is a supporting cylinder.

The feature of this structure is that the amount of electron beam emission is controlled by applying a positive or negative potential to the control grid 34 with respect to the cathode. In order to prevent this, a shadow grid 32 is interposed between the two.

And these cathodes 31. The shadow grid 37 and the control grid 34 have curvature radii R1 and R, respectively.
2 and R3 are formed into concentric spherical shapes, and are arranged with minute intervals g'*g' of about 0.2 m and 0.3 m, respectively.

Furthermore, both grids are perfectly aligned along the electron beam emission trajectory from the entire surface of the cathode. Each grid is also made of a high melting point metal such as molybdenum (Mo).
It is made of a thin plate having a uniform thickness and is formed into a single spherical shape, and has a grid/four turns consisting of a large number of radial slits 41 defined by grid wires 40 having a width of approximately 50 μm.

Conventionally, grids having slits in such a fine grid pattern have been formed by forming the slits by electrical discharge machining or photoetching, and then press-molding them into a predetermined curved shape. However, the manufacturing method using electrical discharge machining requires a large number of man-hours and has the disadvantage that it is difficult to form each slit uniformly. On the other hand, in the photo-etching method, since the metal thin plate material is brittle Mo, there is a disadvantage that the grid wire tends to be partially broken when press-molding is performed after etching the planar glyphs r.

Furthermore, the line width of the grid wires tends to be non-uniform.

[Purpose of the invention]

The present invention has been made in view of one or more circumstances, and it is an object of the present invention to provide a method for manufacturing a spherical grid for an electron tube with uniform slits in the grid pattern and high precision.

[Summary of the invention]

This invention involves a process of coating a thin metal plate made of a material with a high melting point such as 4Mo with a photoresist layer, exposing this layer to light in a predetermined grid of 14 turns, and developing it. A method for producing a spherical grid for an electron tube, comprising the steps of forming a thin metal plate into a spherical shape using a press molding machine, and then etching a large number of slits corresponding to the grid turns in the thin metal plate. be. In particular, before press molding, an organic film is coated on the photoresist layer.
These thin metal plates, photoresist layers, and organic films are stacked and formed into a spherical shape using a press molding machine.The organic film is then peeled off, and then the thin metal plates are formed into a grid/4' turn pattern by etching. This is a manufacturing method that creates slits.

[Embodiments of the invention]

Examples thereof will be described below with reference to the drawings.

Identical parts are designated by the same reference numerals.

The embodiment shown in FIG. 1 first undergoes a resist coating/multi-turn exposure process 11. This process is.

A photoresist layer 1 is placed on one side of a thin Mo material flat plate 17.
In this step, B is applied, a pattern mask IB on which a predetermined grid pattern is drawn is placed in close contact with the pattern mask IB, and exposed as shown by the arrow. Then pattern mask 19 is removed and photoresist layer 18 is developed. Next, an organic film coating step 12 is performed. This step is a step in which an organic film 20 of about 40 μm in thickness, such as glass stick, is entirely deposited on the developed photoresist layer 18 . Preferably, an adhesive layer is formed on the film 2θ so that the film 2θ is brought into close contact with the resist layer 18. Next, press molding process 13
go through. This step is a step in which the thin material plate 17 covered with the organic film 20 is sandwiched between a pair of pre-medium dies 21 and 22 having a predetermined radius of curvature, and press-formed as shown by the arrow. Note that the back surface of the thin material plate 17 may also be coated with an organic film. Next, a film peeling step 14 is performed.

This step is a step of peeling off the resist layer 18 on the spherical thin plate after press molding and the organic film 20 from the back surface of the thin plate. Next, an etching/finishing step 15 is performed.

This step is a step in which the Mo thin plate 17 is chemically etched to leave a grid wire portion corresponding to FIG. 5 due to grid no-turns and a number of radial slits are formed, and then cleaned and finished. Through the above steps, the control grid or shadow grid shown in FIGS. 3 to 5 is completed.

In the embodiment shown in FIG. 2, in the resist coating/multi-turn exposure step 1, photoresist layers 111.1B are coated on both sides of the thin Mo material plate 17, and a grid pattern is exposed from both sides.

And organic film 20.20 on the resist layer on both sides.
is coated, and as it is, it is sandwiched between press dies and press-formed. In this method, the film is peeled off by heating and then etched to form a large number of slits for finishing.

〔Effect of the invention〕

According to this invention, the following effects can be obtained. In other words, the method involves exposing a thin plate of material to a grid pattern, press-forming it, and then etching it to form a large number of slits, so the thin plate of material can be press-formed as it is.

In addition, since the press pressure is applied uniformly to the entire material, M
There is little risk of cracking even in relatively brittle metal materials such as o. Therefore, it is possible to obtain a spherical grid in which the wire portions and slits of the completed grid are uniform and have high precision.

In addition, since different stresses and strains do not remain in the material, deformation of the grid is less likely to occur during use as an electron tube after the grid is completed.

Furthermore, by pressing with the organic film coated on the material to be press-molded and the photoresist layer, the contact between the press die and the film is improved.
Can be molded to a precise radius of curvature. Moreover, since the press die and the thin material plate do not come into direct contact with each other due to the presence of the organic film, it is possible to uniformly form the grid wire portions and slits without damaging the thin material sheet.

In this way, a highly accurate spherical grid can be formed with good reproducibility.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing one embodiment of the present invention. FIG. 2 is a process diagram showing another embodiment of the present invention. FIG. 3 is a vertical cross-sectional perspective view of the main part showing the electron gun structure of the electron tube;
FIG. 4 is a sectional view of the main part, and FIG. 5 is a top view of the main part of the grid. 34... Control grid, 37... Shadow grid, 40... Grid wire, 41... Radial slit, 11... Resist coating/main turn exposure process, 12... Organic film coating process, 13...Press molding process, 14...Film peeling process. 15... Etching/finishing process, 17... Material thin plate. 18... Photoresist layer, 19... Pattern mask, 20... Organic film, 21.22... Press die. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) A process of applying a photoresist layer to a raw metal sheet, exposing a predetermined grid pattern to light, and developing it, and then molding the metal sheet with the photoresist layer still attached into a spherical shape using a press molding machine. A method for manufacturing a spherical grid for an electron tube, comprising a step of molding and a step of etching a large number of slits corresponding to a grid pattern in a thin metal plate. (2) A process of coating a photoresist layer on a raw metal thin plate, exposing a predetermined grid pattern to light, and developing it; Next, a process of depositing an organic film on the photoresist layer; Next, these metal thin plates , photoresist layer, and organic film are laminated and formed into a spherical shape using a press molding machine.Next, the above film is peeled off.After that, a large number of slits corresponding to a grid pattern are formed on the thin metal plate by etching. A method for manufacturing a spherical grid for an electron tube, comprising the step of drilling a spherical grid. (3) The method for manufacturing a spherical grid for an electron tube according to claim 2, wherein an organic film is applied on both sides of a thin metal plate and press-molded.