KR910005189Y1 - Electron gun of crt - Google Patents

Abstract

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Description

Electron gun for cathode ray tube

1 is a partial ablation side view schematically showing a conventional electron gun.

2 is a partial ablation side view schematically showing an electron gun for a cathode ray tube according to the present invention.

FIG. 3 shows the size of the beam spot diameter due to the distance between the lens forming hole and the electrode of the focusing electrode and the anode of the cathode ray tube electron gun shown in FIG.

* Explanation of symbols for main parts of the drawings

K: cathode G ₃ : focusing electrode

G ₄ : Focus electrode G ₅ : Anode electrode

D ₃ , D ₅ : Lens forming hole

The present invention relates to an electron gun for a cathode ray tube. Specifically, the spherical aberration of the beam is improved by appropriately adjusting the spacing between the electrodes constituting the unpotential electron gun, and on the fluorescent surface by a constant focus voltage in a wide range of current ranges. The present invention relates to reducing the spot of the landing beam to improve the resolution of the fluorescent surface.

In general, in the electron gun, factors for determining the size of the beam spot landing on the fluorescent surface include the size of the beam crossover image, the aberration of the electron lens, and the mutual repulsion effect of the space charge.

The above factors are mainly determined by the magnification of the lens and the voltage applied to the electrode. Since the size of the beam spot is closely related to the resolution of the screen, many improvements have been proposed to obtain a smaller beam spot.

Accordingly, the conventional unpotential electron gun has a cathode and a cylindrical G ₁ electrode constituting the front triode, a G ₃ electrode constituting a G ₂ electrode and an auxiliary lens and a main lens, a G ₄ electrode, and a G as shown in FIG. _The electrodes are arranged in order on the same axis at regular intervals, and a predetermined voltage is applied to each electrode, while a positive voltage VB is applied to the G ₃ and G ₅ electrodes while a focus voltage Vf is applied to the G ₄ electrodes. ).

Here, the focus voltage Vf greatly affects the focus characteristic of the electron gun. That is, the beam spot diameter changes according to the beam current and the focus voltage. When the empty current increases, the beam spot diameter increases, while if the beam current is constant, the beam spot diameter changes according to the focus voltage Vf and the predetermined focus voltage Vf. ) Is the minimum. The voltage at this time is called an optimum focus voltage. In this case, when the voltage applied to the G ₄ electrode (focus electrode) is larger or smaller than the optimum focus voltage, the beam spot diameter becomes large or a halo occurs. Even if the optimal focus voltage Vf is applied to the G ₄ electrode, the spherical aberration of the beam becomes large if the distance 1 between the exit side of the G ₃ electrode constituting the main lens and the incidence side of the G ₅ electrode is not appropriate. As a result, the size of the beam spot is not minimized in the use current region, so that high resolution cannot be realized.

Accordingly, the present invention provides an electron gun for cathode ray tube which can reduce the spherical aberration of the beam passing through the electron lens formed by the electrodes constituting the electron gun and form a very small beam spot mirror landing on the fluorescent surface in the use current region. Has its purpose.

In order to achieve the above object, the present invention includes a cathode, a G ₁ electrode, a G ₂ electrode, an auxiliary lens, and a focusing electrode, a focus electrode, and an anode electrode forming a main lens, and the focusing electrode and the anode. In an electron gun in which an equipotential voltage is applied to an electrode, a focus voltage lower than the equipotential voltage is applied to the focus electrode, and a lens forming hole is formed in each of the electrodes, the incident side of the focusing electrode and the incident side of the anode electrode. When the diameter of the lens forming hole formed in the D ₃ , D ₅ and the spacing between the electrodes is L ₃₅ ,

Its characteristic is that it satisfies the expression represented by * 1.2≤χ≤2.0.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. 2 shows a cathode gun for a cathode ray tube according to the present invention, which comprises a cathode, a G ₁ electrode, a G ₂ electrode, and a cylindrical focusing electrode for focusing and accelerating an electron beam in a unipotential focusing manner. ₃ ), the focus electrode G ₄ and the anode electrode G ₅ are arranged in order, and lens forming holes are formed in each of the electrodes, and the incident side of the focusing electrode G ₃ and the anode electrode G _{5 are} arranged. On the incidence side surface of each of the diameters (D ₃ ), (D ₅ ) of the circular lens forming holes are formed. The exit side of the focusing electrode G ₃ and the incidence side of the anode electrode G ₅ are maintained at a constant distance (l ₃₅ ), and are determined by the equation χ = l ₃₅ / [(D ₃ + D ₅ ) / 2]. In the equation expressed, the value χ should be in the range 1.2 to 2.0.

This reduces the spherical aberration of the beam by appropriately adjusting the lens forming holes (D ₃ ), (D ₅ ) formed in the focusing electrode (G ₃ ) and the anode electrode (G ₅ ) and the spacing (l ₃₅ ) of these electrodes. It is to minimize the scene of the spot.

Wherein the general formula For example, the hole diameter of the focusing electrode _{(G 3) (D 3)} = 3.4mmψ focusing electrode (G ₃₎ and the anode electrode as by repeated experiments of the present inventor obtained the diagram illustrated in FIG. 3 the time interval (l ₃₅₎ = 5.89mm anode hole diameter (D ₅₎ = 4.0mmψ distance between the electrode and the size of the lenticular success in determining the beam diameter of the post (G ₅₎ has a value between the same and the Substituting in an expression,

You get a value of 1.59. As can be seen from the diagram shown in FIG. 3, it is possible to obtain a good beam spot in the range of l ₃₅ / [(D ₃ + D ₅ ) / 2] that determines the beam spot, that is, χ in the range of 1.5 to 1.6. In 1.2 or less, the beam cross section passing through the main lens is enlarged to increase the beam spot landing on the fluorescent surface. On the contrary, the spherical aberration of the beam becomes larger than 2.0, and the beam spot diffuses due to the non-focusing phenomenon.

The present invention as described above maintains the best state of the spherical aberration of the beam passing through the electron lens and the beam spot landing on the fluorescent surface by appropriately adjusting the distance between the focusing electrode and the anode electrode and the size of the lens forming hole forming the electron gun for cathode ray tube By making it possible, a cathode ray tube of vivid image quality can be realized.

Claims (1)

And a focusing electrode G ₃ , a focus electrode G ₄ , and an anode electrode G ₅ constituting a cathode K, a G ₁ electrode, a G ₂ electrode, and an auxiliary lens and a main lens. is applied to the focusing electrode (G ₃₎ and an anode electrode (G ₅₎ is applied to the equipotential voltage (VB), the focusing electrode (G ₄₎ has the focusing electrode (G ₃₎ and an anode electrode (G ₅₎ voltage When the lower focus voltage Vf is applied, the diameters of the lens forming holes formed on the beam incident side of the focusing electrode G ₃ and the beam incident side of the anode electrode G ₅ are D ₃ and D ₅ , respectively. Electron gun for cathode ray tube, characterized in that to determine the spacing (l ₃₅ ) between the two electrodes according to the following formula.