JPS63184248A - Electron gun for cathode-ray tube - Google Patents

Abstract

PURPOSE:To shorten a required time in which an image appears by providing a first electrode with reinforced grooves which interpose an electron beam aperture therebetween and have bottom surfaces projecting to a side of a cathode and have approximately U or V-shaped crosssectional areas and making the approximately U or V-shaped crosssectional area's side walls near to the electron beam aperture be formed asymmetrically shorter than the side walls far from the electron beam aperture. CONSTITUTION:Reinforced grooves 1a which interpose electron beam aperture and have bottom surfaces projecting to a side of a cathode 3 and have approximately U or V-shaped cross-sectional areas are provided for a first electrode 1, and the approximately U or V-shaped crosssectional area's side walls near to the electron beam aperture are formed asymmetrically shorter than the side walls far from the electron beam aperture. When such a method is employed and the first electrode 1 is heated by heat radiation of the cathode 3 at the start of operation and so a temperature rises, the reinforced grooves 1a provided for the first electrode 1 are deformed by heat expansion so that the expansion amount of the side walls large in length is larger than that of the side walls small in length and so a surface of the first electrode 1 finally approach the cathode 3. Hence, a large electric field for electron beam acceleration of a second electrode 2 is energized in the vicinity of the cathode 3, and electron beams quickly increase and so brightness also quickly rises.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron gun for a cathode ray tube whose brightness increases quickly at startup.

[Conventional technology]

A cathode ray tube electron gun usually has a cathode that emits electrons, and a -
A first electrode that has a secondary beam passage hole and controls the amount of electron beam passing through the electron beam passage hole according to its potential, and a second electrode that applies an electron beam accelerating electric field to the vicinity of the cathode through the electron beam passage hole of the first electrode. It is equipped with a three-pole system, and the image of the so-called crossover, which is generated when the electron beam is narrowed very narrowly near the second electrode of this system, is transferred to the third electrode of the electron gun.
A main lens consisting of electrodes arranged closer to the fluorescent surface than the polar system forms an image on the fluorescent surface.

In order to generate a small electron beam spot on the fluorescent surface in order to obtain an image with good resolution, the diameter of the electron beam passing hole in the first electrode is made small and the distance between the cathode and the first electrode is also very small. Therefore, 3
In a color cathode ray tube that uses a main electron beam, even a slight deformation of the first electrode has a large effect as a change in the distance between the cathode and the first electrode, causing color variations.

Therefore, conventionally, a protruding reinforcing groove having a U-shaped or V-shaped cross section has been provided between the electron beam passage hole of the first electrode to prevent deformation from occurring. Similarly, since deformation of the second electrode is also undesirable, similar reinforcing grooves are provided in the second electrode as well. The reinforcing groove of the first electrode is made to protrude toward the cathode side so that the protruding part of the reinforcing groove of the first electrode and the protruding part of the reinforcing groove of the second electrode do not come into contact with other electrodes or the protruding part of the reinforcing groove of the electrode. The reinforcing grooves of the two electrodes are made to protrude toward the fluorescent surface side.

Figure 2(a) shows a three-pole system of a conventional electron gun, and in the figure, 2
3 is a second electrode, 3 is a cathode, 4 is a first electrode, and 4a is a reinforcing groove of the first electrode. Moreover, FIG. 2(b) is a top view of the first electrode 4 seen from the BB line cross section shown in FIG. 2(a), and FIG. 2(C) is a side view of the first electrode. As shown in FIG. 2, the reinforcing groove 4a conventionally provided in the first electrode is formed in an asymmetrical shape, with the side wall closer to the electron beam passage hole having a substantially U-shaped cross section being longer than the side wall farther from the electron beam passage hole. Ta. Therefore, when the cathode temperature rises at the time of starting the cathode ray tube, the first electrode 4 is heated by heat radiation from the cathode and the temperature rises.
The electrode surface was displaced in a direction away from the cathode, which slowed down the rise in the amount of electron beam (emission) and suppressed the rate at which screen brightness increased.

[Problem that the invention seeks to solve]

An object of the present invention is to solve the problem that in the conventional electron gun, the brightness of the screen rises slowly at the time of startup, and to provide an electron gun for a cathode ray tube in which the brightness of the screen rises faster than before. shall be.

[Means for solving problems]

In order to solve the above-mentioned problems, in the present invention, a reinforcing groove whose bottom surface protrudes toward the cathode side and whose cross section is approximately U or approximately V-shaped is provided in the first electrode with the electron beam passing hole sandwiched therebetween.
It was decided to form an asymmetrical shape in which the side wall on the side closer to the electron beam passage hole having a substantially U- or V-shaped cross section is shorter than the side wall on the far side.

[Effect]

If such a measure is adopted, when the first electrode is heated by heat radiation from the cathode during startup and its temperature rises, the temperature will increase due to thermal expansion of the reinforcing groove provided in the first electrode and having an asymmetrical U- or V-shaped cross section. As for the deformation, the amount of expansion of the longer side wall is larger than the thermal expansion of the shorter side wall, and as a result, the surface of the first electrode approaches the cathode. As a result, the second
The electron beam accelerating electric field of the electrode becomes stronger, the amount of electron beam rises faster, and therefore the brightness rises faster.

〔Example〕

FIG. 1(a) is a diagram showing a three-electrode system according to an embodiment of the present invention, in which 1 is a first electrode according to the present invention, 1a is a reinforcing groove, 2 is a second electrode, and 3 is a cathode. . Moreover, FIG. 1(b) is a top view of the first electrode 1 seen from the section taken along the line AA shown in FIG. 1(a), and FIG. 1(C) is a side view of the first electrode. In this way, when the cathode ray tube is started, as the temperature of the first electrode 1 rises, the vicinity of the electron beam passage hole of the first electrode 1 approaches the cathode surface. As a result, the electron beam accelerating electric field of the second electrode 2 acting on the surface of the cathode 3 becomes stronger, the amount of electron beam rises faster, and the brightness of the screen increases faster.

〔Effect of the invention〕

As explained above, according to the present invention, after starting the cathode ray tube,
The time required until an image that can be observed by the user appears is shortened.

[Brief explanation of the drawing]

FIG. 1(a) is a diagram showing a three-pole system according to an embodiment of the present invention.
Figure (b) is a top view of the first electrode according to the present invention as seen from the cross section along line A-A, Figure 1 (c) is a side view of the first electrode of the present invention, and Figure 2 (a) is a conventional electronic Diagram showing the three-pole system of a gun, Figure 2 (
b) is a top view of the conventional first electrode seen from the BB line cross section;
FIG. 2(C) is a side view of the conventional first electrode.

Claims (1)

[Claims] 1. A cathode that emits electrons, a first electrode that has an electron beam passage hole and controls the amount of the electron beam passing through it depending on its potential, and an electron beam that is accelerated near the cathode through the electron beam passage hole of the first electrode. 3 consisting of a second electrode that applies an electric field;
In an electron gun for a cathode ray tube having a polar system, a reinforcing groove whose bottom surface protrudes toward the cathode side and whose cross section is approximately U or approximately V-shaped is provided in the first electrode across the electron beam passage hole.
Alternatively, an electron gun for a cathode ray tube is formed in an asymmetrical shape in which a side wall closer to the electron beam passage hole having a substantially V-shaped cross section is shorter than a side wall farther from the electron beam passage hole.