JPH0427083Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application in Production] The present invention relates to a cathode ray tube (hereinafter referred to as CRT).

[Conventional technology]

In recent years, as a new display device,
Research and development of PDP, EL, LED, LCD, ECD, etc. is progressing, but as a practical device that can display bright and sharp moving images, there is nothing better than the CRT method in terms of overall performance and price. is the current situation. The biggest application of CRT is in TV picture tubes.
In addition, it is widely used for measurement, observation, computer terminal display, etc. It is also used as a viewfinder as a monitor for a video camera, and there is a demand for smaller size, lighter weight, and lower cost.

FIG. 4 is an example of a CRT structure manufactured by the prior art. The main parts are a panel 1, a metal funnel 2, a net 3, an electron gun 4, and a carbon coating 5. FIG. 2 is an enlarged structural diagram of the vicinity of the electron gun, and the electron gun 4 is mainly composed of an accelerating electrode 6, a control electrode 7, and a cathode 8.
As shown in Fig. 3, the lens system of the electron gun is mainly composed of three parts: a cathode lens, a prefocus lens, and an electron beam emitted from the cathode 8. 7. A crossover is formed by a cathode lens constituted by an accelerating electrode 6. Next, the carbon coating 5 applied to the inner wall of the net is set to the same potential as the anode and used as an electrode, and the beam is focused in advance by the prefocus lens formed between the accelerating electrode 6 and the optimum beam at the main lens. Adjust the beam to give.

[Problem that the invention attempts to solve]

As shown in Figures 4 and 2, in the method of applying a carbon film to the inner wall of the net, the positional accuracy of the end face of the carbon film 5 on the electron gun side is low, causing distortion of the prefocus lens and distortion of the screen. This causes a problem of lower resolution.

Another disadvantage is that it requires a large number of man-hours to apply the carbon film.

[Means for solving the problem]

In order to solve the above problem, in the present invention, in a CRT having at least a panel, a metal funnel, a net, and an electron gun, the end surface of the metal funnel on the electron gun side is made longer in the direction of the electron gun, and the component parts of the electron gun are made longer. The electron beam was placed at a position where a prefocus lens for the electron beam was formed between the electron beam and the accelerating electrode.

〔Example〕

FIG. 1 is a structural diagram of a CRT which is an embodiment of the present invention. The panel 1, network 3, and electron gun 4 are the same as before. In this embodiment, the prefocus lens is formed with the accelerating electrode of the electron gun 4 on the end surface of the metal funnel 12 on the electron gun side without applying a carbon film, rather than with the carbon film electrode applied to the inner wall of the neck. was extended to the pole surface of the accelerating electrode and set to the same potential as the anode, and a prefocus lens was formed with this metal funnel electrode. Further, the metal funnel was joined by welding to the neck.

[Effects of the Invention] According to the present invention, by lengthening the end face of the metal funnel on the electron gun side in the direction of the electron gun, it is not necessary to apply a carbon film, reducing the number of manufacturing steps and lowering costs. In addition, the positional accuracy of the end face of the metal funnel on the electron gun side is increased because it is a metal that is easy to process, and the distortion of the prefocus lens is reduced, improving the image quality.This invention is advantageous from an industrial standpoint. is also valid.

[Brief explanation of drawings]

FIG. 4 is a structural diagram of a CRT manufactured by the prior art, and FIG. 2 is an enlarged view of the vicinity of the gun in FIG. 4. FIG. 3 is a diagram of a CRT lens system. Figure 1 is an example of the present invention.
It is a structural diagram of a CRT. 1... Panel, 2, 12... Metal funnel,
3... Net, 4... Electron gun, 5... Carbon film, 6... Accelerating electrode, 7... Control electrode, 8... Cathode.

Claims (1)

[Scope of utility model registration request] At least panels, metal funnels, nets,
In a cathode ray tube having an electron gun, an end surface of the metal funnel on the electron gun side is lengthened in the direction of the electron gun;
A cathode ray tube characterized in that the cathode ray tube is disposed at a position to form a prefocus lens for an electron beam between it and an accelerating electrode that is a component of an electron gun.