JPS5927015Y2 - Electrostatic deflection type cathode ray tube - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electrostatic deflection type cathode ray tube equipped with a shield mesh electrode for post-acceleration.

Generally, observation type cathode ray tubes are electrostatic deflection type cathode ray tubes, and such cathode ray tubes adopt a post-acceleration type.

In the post-acceleration format, the electron beam is accelerated by a low-voltage electric field until it passes through the electrostatic deflection electrode system, and the electron beam after deflection is accelerated by a high-voltage electric field, so high brightness characteristics are achieved without reducing deflection sensitivity. can be obtained.

A post-acceleration type electrostatic deflection cathode ray tube is usually constructed as shown in Fig. 1, where 1 is a glass bulb, 2 is an electron gun, and 3 is a glass bulb.
, 4 is an electrostatic deflection electrode, 5 is a cylindrical shield electrode, 6 is a substantially hemispherical shield mesh electrode, 7 is a conductive film coated on the inner surface of the funnel portion of the bulb 1, and 8 is a phosphor screen. show.

The purpose of the shield mesh electrode 6 is to prevent the electron beam 9 emitted from the electron gun and deflected by the electrostatic deflection electrode 3 for vertical deflection and the electrostatic deflection electrode 4 for horizontal deflection into the primary beam in the deflection system. The purpose is to prevent these electric fields from penetrating each other at the boundary point where they fly from the accelerating electric field to the post-accelerating electric field, which has a higher voltage.

In addition, by molding the shield mesh electrode 6 into a rotationally symmetrical shape that is convex in the traveling direction of the electron beam 9 to form a so-called domed mesh, the electric field on the high electric field side of the mesh after acceleration is made into a concave lens to deflect the electron beam 9. Products that allow for expansion have also been put into practical use.

The outline is shown in Fig. 2 a, l).

Generally, the shield mesh electrode 6 has an area larger than the effective area A necessary for transmitting the electron beam.

This extra area B is the shield mesh electrode 6.
This is the area necessary to mold the material into a dome shape, hold and reinforce that shape.

In particular, as shown in the figure, the outer peripheral area of the shield mesh electrode 6 is raised in a straight line, then it is made to have a certain angle C, and then
When the bottom is shaped like a dome with curvature, the structure of the entire dome mesh becomes extremely strong.

However, such a structure tends to scatter the electron beam 9 when the part is irradiated with the electron beam 9, which may hit the phosphor screen 8 and cause halation emission.

Further, even if the shield mesh electrode 6 does not have a special structure, the electron beam may be reflected by the edge surface of the frame 10 to which the mesh is attached, and similarly, halation light emission may occur.

In this case, the same applies to a flat mesh in which the shield mesh electrode 6 is not dome-shaped.

Further, this halation emission occurs particularly when the phosphor screen is not backed by an aluminum vapor-deposited film or the like.

An object of the present invention is to provide an electrostatic deflection type cathode ray tube that can prevent this halation emission.

The present invention will be described below with reference to the drawings and embodiments.

FIG. 3 is a sectional view of a main part showing an embodiment of the present invention, and FIG. 4 is a configuration diagram of the main part.

In the present invention, an electron beam 9' that reaches outside the effective area of the shield mesh electrode, which causes halation, is blocked by a shielding plate 11 immediately before it hits the shield mesh electrode 6, thereby preventing halation emission.

This shielding plate 11 can have a donut ring shape, for example, but it is preferable that its thickness be as thin as possible.

This is because electrons are more likely to be reflected at the edges of a thick plate, and the thickness is preferably 0.3 mm or less.

Further, it is desirable that the shielding plate 11 be installed in the immediate vicinity of the shield mesh electrode 6 on the electron gun side.

This is not preferable on the phosphor screen side of the shield mesh electrode 6 because it will affect the deflection magnifying lens formed by the shield mesh electrode 6 and the subsequent accelerating electric field.

Moreover, if it is installed in the immediate vicinity of the shield mesh electrode 6, the positioning of the shield plate 11 and the shield mesh electrode 6 becomes easy and accurate, and the area outside the effective area of the electrode 6 can be accurately shielded.

As mentioned above, the cathode ray tube of the present invention has a shield mesh electrode that is composed of an outer circumferential area rising linearly from the periphery and a dome-shaped effective area curved at a certain angle with respect to this outer circumferential area. A ring-shaped metal plate is disposed between the electron deflection electrode and the phosphor screen and is used to shield electron beams other than the electron beams directed from the electron gun toward the effective area. Since the mesh electrode is attached to the mesh electrode, it is possible to increase the mechanical strength of the mesh electrode and completely prevent halation light emission caused by the electron beam hitting the outer circumferential area or the peripheral area.

Further, the light shielding plate and the shield mesh electrode can be easily and accurately aligned.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional electrostatic deflection cathode ray tube, Figure 2a
, l) are a plan view and a sectional view of a shield mesh electrode, FIG. 3 is a side sectional view of a main part showing an embodiment of the present invention, and FIG. 4 is an exploded perspective view of FIG. 3. 2... Electron gun, 3, 4... Deflection electrode,
5... Shield electrode, 6... Shield mesh electrode, 11... Metal shielding plate.

Claims (1)

[Scope of utility model registration request] Between the electrostatic deflection electrode and the phosphor screen, a shield mesh electrode consisting of an outer peripheral area rising linearly from the periphery and a dome-shaped effective area curved at a certain angle with respect to this outer peripheral area is installed. and an annular metal plate is attached to the electron gun side of the peripheral portion for shielding electron beams other than the electron beams directed from the electron gun toward the effective area. Electrode deflection type cathode ray tube.