JPS5919407B2 - Electron gun for cathode ray tube - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electron gun for a cathode ray tube.

There are various types of electron guns for cathode ray tubes, but usually pi-potential type electron guns and uni-potential type electron guns are used depending on the purpose.

The former, which has excellent focusing characteristics, is mainly used in high-resolution picture tubes.

A bipotential type electron gun has a cathode, a control grid electrode, an accelerating electrode, a first anode, and a second anode arranged in this order. After being focused into a beam by a prefocus lens formed by the first anode and the second anode,
The light is focused by the main lens formed by the anode and hits the phosphor screen surface.

Note that an auxiliary focusing electrode is provided between the control grid electrode and the accelerating electrode to form a so-called pentode structure, and in this case, even better focusing characteristics can be obtained.

In the cathode ray tube electron gun mentioned above, in order to reduce the diameter of the electron beam (beam spot diameter) that impinges on the phosphor screen surface, it is important to minimize the spherical aberration of the electron lens, especially the main lens. be.

To achieve this, it is sufficient to increase the diameter of the first and second anodes, but in order to increase the diameters of the first and second anodes, it is necessary to increase the diameter of the valve neck that houses the electron gun. Therefore, increasing the diameter of the valve neck reduces the deflection sensitivity.

For this reason, conventionally, as shown in FIG. 1, the cathode 1.degree. control grid electrode 2.degree. Auxiliary focusing electrode 3. Accelerating electrode 4゜A first anode 5 and an insulator 6 for insulating and supporting these electrodes are housed in a pulp neck portion 7, and a second anode 8 made of a conductive film such as graphite is placed on the inner surface of the neck portion 7 made of glass. Adhesive formation was performed.

In this case, the diameters of the first anode 5 and the second anode 8 can be set larger without increasing the diameter of the valve neck 7, but the roundness of the valve neck 7 and the second anode 8 is low, and the Also, there is a spring 9 on the inner surface of the valve neck part 7.
The first anode 5 and the second anode 8 are elastically supported by
Therefore, even though the diameters of the first anode 5 and the second anode 8 are set large,
There was a problem in that it was difficult to reduce the aberration of the main lens very much.

The inventor's earlier application, Japanese Patent Application No. 115523/1983, solved the above-mentioned problem, and FIG. 2 shows an embodiment of the invention.

In FIG. 2, cathode 1. Control grid electrode2. Auxiliary focusing electrode 3. Accelerating electrode 4. The first electrode 10 and the second anode 11 are insulated and supported by a common insulator rod 12 and housed in the valve neck 7 .

The second anode 11 has a small-diameter support end 13 at the edge on the first anode 10 side, and is supported by the insulating rod 12 at this small-diameter support end 13 .

Further, the conductive tongue piece 14 attached to the tip of the second anode 11 supplies the second anode 11 with a high voltage applied through the conductive film 15 deposited on the inner surface of the valve neck portion 7 .

The first anode 10 has a neck portion 16 that passes through the small diameter support end portion 13 of the second anode 11 without contacting it, and a large diameter tip portion 17 located within the large diameter cylindrical portion of the second anode 11. A main lens is formed between this large-diameter tip portion 17 and the large-diameter cylindrical portion of the second anode 11 .

According to the electron gun having the above configuration, the roundness of the second anode and the roundness of the first anode. The coaxiality of the second anode is improved, and a large-diameter main lens with little spherical aberration can be obtained without increasing the bulb neck diameter, and the beam spot diameter can be reduced.

The above is the structure of the electron gun for cathode ray tubes shown in the specification of the prior application, but the inventor of the present invention has determined the diameter of the electron beam (beam spot diameter) that strikes the surface of the phosphor screen regarding the electron gun for cathode ray tubes. As a result of conducting research to further reduce the size of , the following problems were discovered.

In other words, in order to further reduce the diameter of the electron beam (beam spot diameter), it is effective to increase the main lens aperture and increase the voltage of the second anode, but increasing the voltage may cause problems with high voltage quality. It's coming.

In FIG. 2, the second anode 11 includes a conductive tongue 14.
In addition, in order to maintain the vacuum inside the bulb, a getter 18 is attached toward the screen or toward the neck tube wall, and is scattered in all directions by high-frequency heating.

These getter scattered particles are particularly concentrated at the large-diameter tip portion 1T of the first anode 10.
If it adheres to the second anode 11, a discharge phenomenon occurs between the second anode 11 and the higher the pressure of the second anode, the greater the effect.

FIG. 3 shows a flat plate shielding electrode structure used in an electron gun to prevent getter 18 from scattering to first anode 10. As shown in FIG.

This flat plate shielding electrode 20 has a hole having a diameter φa' in the center so as not to obstruct the flow of the electron beam to the screen surface.

In this case, a contradiction arises in that in order not to impede the flow of the electron beam, a hole diameter as large as possible is required, while in order to prevent the getter 18 from scattering, a hole diameter as small as possible is required.

The present invention was made to solve the above problems, and
The present invention provides a cylindrical shielding electrode with a new structure that can replace the conventional flat plate shielding electrode that prevents getter from scattering to the first anode and does not impede the flow of electron beams to the screen surface. The present invention provides an electron gun in which the aperture of the main lens can be made larger than in the past and the voltage of the second anode can be made even higher by means of electrodes.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG.

As shown in FIG. 4, the electron gun of the present invention has a chimney-shaped cylindrical part having an inner diameter ψa and a hole having an inner diameter ψa on the end face of the second anode 11 so as to shield the tip diameter. Electrode 19
has.

In this cylindrical electrode 19, φa≧φb due to its structure, and although it is possible that φa=φb, the electron beam passes through the cylindrical electrode tip rather than through the second anode tip. Since the beam diameter is smaller when the aperture is used, it is desirable to set the hole diameter φb so that it becomes φCφb, since this increases the effect on the getter scattering section.

By the way, when the valve neck inner diameter BD is set to 31 mm, the inner diameter P2D of the second anode 11 is 26#! t, the inner diameter P1D of the large diameter tip 17 of the first anode 10 is set to 20 mm, the inner diameter PID' of the neck part 16 is set to 12.4 mm, and the inner diameter φa of the cylindrical part of the cylindrical part electrode 19 is set to 11 mm.
The tip hole diameter φb can be set to 9 mm.

Furthermore, the large diameter cylindrical portion P2L of the second anode 11 is 40 mm.
m, the large-diameter tip portion P1L of the first anode 10 can be set to 16 mm, and the electrode height C in the cylindrical portion can be set to 16 mm.

On the other hand, in the case of no auxiliary focusing electrode, the voltage applied to each electrode is as follows: Control grid electrode......OV Accelerating electrode...460-740v 1
Anode voltage...6.0~7.2 KV 2nd
Anode voltage: Can be set at 30 KV.

As mentioned above, the cathode ray tube electron gun of the present invention is
Advantages of the electron gun described in the specification of No. 3-115523,
In other words, the roundness of the second anode and the coaxiality of the first and second anodes are good, and the following new effects are achieved without sacrificing the advantages of having a large diameter lens with little spherical aberration. It is something to have together.

In other words, a cylindrical shielding electrode for shielding the getter scattering section is provided coaxially with the large-diameter cylindrical part of the second anode, and a small-diameter cylindrical part is provided at the tip of this shielding electrode, so that the distribution of the electron beam is prevented. This prevents getter particles from adhering to the electrodes without causing any problems, and high voltage quality can be maintained even when high voltage (20 to 30 KV) is applied to the second anode.

In particular, it can be applied to electrostatic focusing type dosing tubes to obtain high resolution and high pressure quality.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional electron gun for cathode ray tubes, FIG. 2 is a side sectional view of the electron gun according to the prior application, FIG. 3 is a side sectional view of the tip of the second anode with a flat shielding plate attached, and FIG. FIG. 4 is a side sectional view of the electron gun for a cathode ray tube according to the present invention. 1...Cathode, 2...Control grid electrode, 3
...Auxiliary focusing electrode, 4...Acceleration electrode,
DESCRIPTION OF SYMBOLS 10...First anode, 11...Second anode, 12...Insulating rod, 13...Minimum support end of second anode, 16... ... Neck part of the first anode, 17 ... Large diameter tip part of the first anode, 19 ...
...Electrode on the cylindrical part.

Claims (1)

[Claims] 1 A cathode, a control grid electrode, an accelerating electrode, a first anode, and a second anode are arranged in this order, and these electrodes are insulated and supported by an insulating rod, and the first anode is provided with a small-diameter support for the second anode. In the cathode ray tube electron gun, the cathode ray tube electron gun has a neck portion that penetrates without contacting the end portion, and a large diameter tip portion for forming a main lens that is connected to the neck portion and is located within the large diameter cylindrical portion of the second anode. A cathode ray tube electronic device characterized in that a cylindrical shielding electrode for shielding getter particles is coaxially provided on the large diameter cylindrical part of the second anode, and a small diameter cylindrical part is provided at the tip of the shielding electrode. gun.