KR920002495Y1 - Multi-step type electron gun - Google Patents

Abstract

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Description

Multi-Stage Focusing Gun for Cathode Ray Tubes

1 is a schematic longitudinal cross-sectional view of a conventional multi-stage focused electron gun.

Figure 2 is a schematic longitudinal cross-sectional view of a multi-stage focused electron gun for cathode ray tube according to the present invention.

* Explanation of symbols for main parts of the drawings

G1 to G8: Electrode H ₅ b: Lens forming hole of G5 electrode

H ₆ b: Lens forming hole of G6 electrode H ₇ b: Lens forming hole of G6 electrode

The present invention relates to a multi-stage focused electric field gun for cathode ray tubes, and more particularly, to reduce the divergence of the electrostatic lens, thereby improving spherical aberration and focus characteristics of the lens, thereby realizing a high resolution image.

A general multi-stage electron gun has a shape as shown in FIG. 1, which includes a control electrode G1 for controlling electrons emitted from a cathode (cathode) and a screen electrode G2 for forming an electron beam, formed therein. It consists of a plurality of focusing electrodes G3 to G8 for focusing and accelerating the electron beam to be rendered on the fluorescent surface.

The multi-focus electron gun is formed of a complex BPF type (Bi-Potential Focus Type) capacitive lens according to a voltage application method of the connection electrodes constituting the multi-stage electron gun.

The BPT (Bi-Potential Focus Type) electron lens constitutes the main legs of the multi-stage focused electron gun, which is applied to two electrodes G7 and G8 facing each other so that these electrodes G7 ( This is to focus the electron beam passing through the electron lens formed by G8). That is, when the electron beam proceeds from the low potential side to the high potential side, the electron beam is focused on the low potential side and diverges from the high potential side.

On the other hand, the unipotential focus (UPF) type electron lens constitutes a pre-focus lens of the electron gun, which is formed by adjacent G5, G6, and G7 electrodes. At this time, an equipotential focus voltage V2 is applied to the G5 and G7 electrodes, and a voltage V1 lower than the V2 voltage is applied to the G6 electrodes located at the electrodes G5 and G7.

Here, when the voltage applied to the electrode is V1 < V2, the electron lens formed by these potential difference is divergent-convergent- divergence action. In some cases, when the voltage is V1 < It works.

The electron gun for the cathode ray tube focuses electrons emitted from the cathode to reach the fluorescent surface, and thus the focusing lens is in a more important position than the diverging lens. Here, in the conventional multi-stage focused electron gun, the electron lens forming holes formed in the electrodes G3 to G8 constituting the main lens are formed at the same line, and the G6 electrode has a potential lower than that applied to the G5 and G7 electrodes. Because of the application, the unipotential focus type electron lens formed on these electrodes simultaneously has a divergence-focusing-diffusion lens. Further, since the lens forming holes H5a, H6a, and H7a formed in the G5, G6, and G7 electrodes have the same diameter, the diverging lens and the focusing lens are formed with the same diameter.

Accordingly, the electron beam passing through the unpotential electron lens receives a large divergence force, and when passing through the main lens formed by the G7 electrode and the G8 electrode, the electron beam passes through the outer edge of the lens and receives a lot of spherical aberration, thereby improving focus characteristics. It is greatly degraded.

Therefore, in a cathode ray tube with such an electron gun, a clear image cannot be expected.

The object of the present invention is to provide a multi-stage focused electron gun for cathode ray tubes with an improved electrode structure to reduce spherical aberration and improve focus characteristics.

In the multi-stage focusing electron gun including a cathode, a G1 electrode, and a G2 electrode forming the transposition triode, and having a plurality of electrodes constituting at least one unpotential electron lens, to achieve the above object, the unpotential electron lens The feature is that the lens forming hole of the electrode located in the center of the adjacent three electrodes forming a larger than the diameter of the lens forming hole of any of the electrodes located before and after.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. 2 is a cathode G1 electrode and G2 electrode for the cathode ray tube according to the present invention, the cathode G1 electrode and G2 electrode constituting the pre-triode, and G3 electrode, G4 electrode, G5 electrode to focus and accelerate the electron beam therefrom , G6, G7 and G8 electrodes are aligned and fixed at appropriate intervals, while the lens forming holes H6b of the G6 electrodes are larger than the lens forming holes H5b and H7b of the G5 and G7 electrodes positioned before and after them. In addition, a potential lower than that of the G5 electrode and the G7 electrode is applied to the G6 electrode, and the G5 electrode and the G7 electrode are applied at the equipotential. On the other hand, the diameters of the lenticular successes of the G5 and G7 electrodes may be the same, and in some cases the diameter of the lens forming hole (H5b) or (H7b) of either electrode is larger than that of the lens forming hole (H6b) of the G6 electrode. It may be formed small.

The multi-stage focused electron gun for a cathode ray tube according to the present invention primarily focuses and accelerates electrons emitted from a cathode (cathode) by a second auxiliary lens formed by a G 3 electrode, a G 4 electrode, and a G 5 electrode. In this case, the second auxiliary lens formed by the G6 electrode G7 electrode is focused and accelerated, and the final focusing and acceleration is performed by the main lens formed on the G7 electrode and the G6 electrode. The potential applied to the G6 electrode of the G5 electrode, the G6 electrode, and the G7 electrode constituting the second auxiliary lens is lower than the potential applied to the G5 electrode and the G7 electrode. The passing electron beam receives divergence-focusing-divergence in that order. However, since the lens formation holes at the exit side of the G5 electrode and the entrance side of the G7 electrode are formed relatively less than the lens formation holes of the G6 electrode, the divergence section of the unpotential focus type second auxiliary lens formed thereby is reduced. That is, by weakening the divergence of the electron lens, the focusing lens formed on the G6 electrode, which is the focusing section, can be easily focused even with a small magnification.

Further, by diminishing the divergence force in the divergence section of the unpotential second auxiliary lens, the bipotential main legs formed by the electrode, the G7 electrode, and the G8 electrode can be focused at a final rate with a small magnification. Accordingly, the spherical aberration and focus characteristics of the electron lens can be improved and a high-resolution color cathode ray tube can be realized.

Claims (1)

A cathode control electrode and a screen electrode constituting the pre-triode tube portion, G3, G4 and G5 electrodes constituting the first auxiliary lens, and G6 and G7 electrodes disposed adjacent to the G5 electrode to form a unpotential second auxiliary lens; In the multi-stage focusing electron gun for cathode ray tubes provided with a G8 electrode disposed adjacent to the G7 electrode to form a bipotential main lens, the lens forming hole of the low potential side G6 electrode constituting the unpotential second auxiliary lens. A multistage focused electron gun for cathode ray tubes, characterized in that (H6b) has a diameter larger than the lens forming holes (H5b) and (H7b) of the high-potential side G5 and G7 electrodes before and after.