JPS63266734A - Electron gun for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To increase the diameter of the center cylinder section and improve the focus characteristic by forming the height in the center axis direction of the center cylinder sections of a main lens forming electrode lower than the height in the center axis direction of the inside of both side cylinder sections. CONSTITUTION:The height lc in the center axis S direction of the center cylinder sections 6c', 7c' of the fifth grid 6 and the sixth grid 7 constituting a main lens is formed lower than the height ls in the center axis S direction of both side cylinder sections 6s1, 6s2 and 7s1, 7s2. The diameter of the main lens constituted of the fifth grid electrode 6 and the sixth grid electrode 7 is effectively made a large diameter, and the focusing voltage of the center cylinder sections 6c', 7c' is reduced, thus it can be made to almost coincide with the focusing voltage of both side cylinder sections 6s1, 6s2 and 7s1, 7s2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an in-line color cathode ray tube electron gun, and particularly to an electrode structure of an electron lens forming electrode suitable for improving focus characteristics.

[Conventional technology]

In an in-line type electron gun, each electron beam is arranged on one plane, so the diameter of the main lens is smaller than that in a delta type electron gun. Due to constraints such as deflection power and convergence, the smaller the diameter of the neck, the better; however, if the diameter of the main lens is even smaller, the focus characteristics will deteriorate.

In addition, the gap between the outer diameter of the electron gun and the inner diameter of the neck is set to 1ws, for example, in order to reduce the influence of undesirable electron radiation.
However, there are many restrictions that prevent the diameter of the main lens from being increased. Therefore, a multi-stage focusing electron gun has been proposed as a means to improve focusing performance under many constraints. This multi-stage focusing electron gun can focus the electron beam gently and can improve the spherical aberration of the electron lens.

FIG. 2 is a partially cutaway view of a typical multi-stage focusing electron gun. In the figure, the electron gun has a cathode 1. 1st grid 2. 2nd grid 3. Third grid 4. 4th grid 5. It is composed of a fifth grid 6 and a sixth grid T, and the main lens is the third grid 4. 4th grid 5
The fifth grid 6 forms one lens system, and the fifth grid 6 and sixth grid 7 form another lens system. Further, the third grid 4 and the fifth grid 6 are electrically connected, and a focus voltage, for example, about 7 KV is applied, and the fourth grid 5 and the sixth grid 7 are electrically connected, and an anode voltage, for example, is applied. Approximately 25 KV is applied, and the electron gun as a whole is a multi-stage focusing electron gun that combines a pi-potential type and a uni-potential type, and has greatly improved focusing characteristics.

The structure of such an electron gun for a color cathode ray tube is described in, for example, Japanese Patent Laid-Open No. 57-63750.

[Problem that the invention seeks to solve]

However, in the multi-stage focusing electron gun having the above-described configuration, the fifth grid 6 and the sixth grid constituting the main lens
As shown in FIG. 3, the grid 7 is formed with cylindrical portions 6c and 7C in the center, respectively, and cylindrical portions 681° and 7aljl1m having a constant inclination angle and different shapes on both sides. The heights tc and ts of the central cylindrical portion 7C of the grid 7 and the cylindrical portions 7°□, 7□ on both sides in the direction of the central axis S are equal<10-1. ), but the central axis S of the central cylindrical portion 7C and both side cylindrical portions 711jall is
Comparing the heights in the directions, both cylindrical parts 7111, 7! II
The inside of I is equivalent to the central cylindrical part 7c, and the height of the outside is lower than that of the central cylindrical part 7C. Therefore, since the cylindrical portions 711.7.2 on both sides have a larger diameter than the central cylindrical portion 7c, the focus voltage decreases. In addition, E
indicates equipotential lines. Generally, the focus voltage of an electron gun decreases as the main lens aperture increases.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide an electron gun for a color cathode ray tube in which the diameter of the central cylindrical portion can be increased to improve focus characteristics. It is in.

[Means for solving problems]

In the electron gun for a color cathode ray tube according to the present invention, the height of the central cylindrical portion of the main lens forming electrode in the central axial direction is lower than the height of the inner sides of both cylindrical portions in the central axial direction.

[Effect]

In the present invention, by reducing the height of the central cylindrical portion, the aperture of the central cylindrical portion is increased, and the focus voltage can be made the same between the central cylindrical portion and both cylindrical portions.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a main part showing an embodiment of an electron gun for a color cathode ray tube according to the present invention, and the same parts as in the previous figures are given the same reference numerals. In the same figure, the respective central cylindrical parts 60'' and 7c' of the fifth grid 6 and the sixth grid 7 constituting the main lens have the same height to in the direction of the central axis S, and each The central axis S of both cylindrical parts 'Il+6111 and γ81,711B
It is formed to have a relationship of /-s>le with respect to the height t in the direction.

According to such a configuration, the respective central cylindrical portions 6 C1 and 7 C of the fifth grid 6 and the sixth grid 7
The height te in the central axis S direction of the
at, 61g and central axis S of 71111711!1
By forming the height smaller than the height t in the direction, the fifth
The diameter of the main lens formed by the grid electrode 6 and the sixth grid electrode 7 is effectively large, and the diameter of the main lens formed by the grid electrode 6 and the sixth grid electrode 7 is effectively large.
The focus voltages of cl and 7Ct will be reduced, and therefore both cylindrical parts 6. l.

61. and 7 ml, which can almost match the focus voltage of T12.

In addition, in the above-described embodiment, a case has been described in which the height of the central cylindrical portions of both the fifth grid and the sixth grid in the central axis direction is lowered, but this is not limited to the present invention. Of course, the same effect can be obtained by changing the height of either the grid or the sixth grid in the central axis direction.

〔Effect of the invention〕

As explained above, according to the present invention, by increasing the lens aperture of the cylindrical portion that is not inclined with respect to the central axis, the focus voltage is lowered and made equal to the focus voltage of the cylindrical portions on both sides. , an extremely excellent effect can be obtained in that an electron gun for a color cathode ray tube having better focusing characteristics can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an embodiment of an electron gun for a color cathode ray tube according to the present invention, FIG. 2 is a sectional view of a main part showing a conventional electron gun for a color cathode ray tube, and FIG. FIG. 6 is a sectional view showing a fifth grid and a sixth grid. 6...5th grid, 6c'...Central cylindrical part, 6sl, 6B...Both cylindrical parts, 1...6th grid, 7C'...Central cylindrical part, 7fil +7
1H: Cylindrical part on both sides.

Claims (1)

[Claims] 1. a first electrode means for directing at least two electron beams along initial paths parallel to each other toward a fluorescent surface; and forming a substantially separate main lens in each said electron beam path; a second electrode means for focusing the electron beam on the fluorescent surface, the electrode means having an opening whose central axis coincides with the electron beam passage, and which are arranged facing each other at a distance from each other, and are arranged opposite to each other at a distance from each other; In an electron gun for a color cathode ray tube whose one end is inclined with respect to the central axis, the height of the inclined cylindrical portion in the direction of the central axis is formed higher than the height of the non-inclined cylindrical portion. Features a color cathode ray tube electron gun.