JPH1050231A - Electron gun for cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a crack in a neck part or a bead glass, by tilting an electrically insulating supporting rod to which plural electrodes are fitted so that a facing interval with the neck part inner surface can be larger on a cathode electrode side than on an anode electrode side. SOLUTION: In an electron gun for a cathode-ray tube, a cathode electrode 1, a first grid electrode 3 for controlling an emitted electron beam, a second grid electrode 4 for accelerating the electron beam, a third grid electrode 5 for focusing the electron beam, and an anode electrode 6 are arranged in coincidence with the center axis conformed. A pair of bead glasses 7, which are an electrically insulating supporting rod, are fixed to, and retained on the peripheries of respective electrodes 1, 3, 4, 5, and 6. The bead glasses 7 are tilted to the center axis of the electron gun so that a facing interval with the inner surface of a neck part 10 can be larger in a part on the cathode electrode 1 side than on the anode electrode 6 side. This can increase the interval between the metallic wire of a conductive lead and the inner surface of the neck part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for a cathode ray tube, and more particularly to an electron gun for a cathode ray tube which can prevent a neck portion of a cathode ray tube in which an electron gun is housed from cracking.

[0002]

2. Description of the Related Art FIG. 4 is a view showing a structure of a conventional electron gun for a cathode ray tube by breaking a neck portion of the cathode ray tube. In the figure, reference numeral 1 denotes a cathode electrode, which is heated by a heater 2 and emits an electron beam. Reference numeral 3 denotes a first grid electrode for controlling an electron beam emitted from the cathode electrode 1, reference numeral 4 denotes a second grid electrode for accelerating the electron beam controlled by the first grid electrode 3, and reference numeral 5 denotes a second grid electrode for accelerating the electron beam. A third grid electrode 6 for converging the electron beam is an anode electrode electrically connected to an anode for supplying a high voltage of a cathode ray tube, and these electrodes 1, 3, 4, 5 and 6 have a central axis. The electron beams are sequentially aligned in the emission direction of the electron beams.

A pair of bead glasses 7 are arranged around the electrodes 1, 3, 4, 5 and 6 and extend in parallel with the central axis. By embedding the ends of the electrodes 3 and 4 in the bead glass 7, the electrodes 3, 4, 5 and 6 are fixed and held in a predetermined positional relationship. Reference numeral 9 denotes a metal wire having both ends fixed to the second grid electrode 4 and disposed so as to surround the outer surface of the bead glass 7 and to be interposed between the inner wall surface of the neck portion 10 and the outer surface of the bead glass 7. This is provided so that discharge due to the accumulated electric charge does not occur on the cathode electrode 1 side with respect to the second grid electrode 4. The electron gun having such a configuration is housed and held in the neck portion 10 with its central axis coinciding with the central axis of the neck portion 10.

In a cathode ray tube equipped with an electron gun having such a configuration, an electron beam emitted from a cathode electrode 1 is focused and controlled by grid electrodes 3, 4, 5 and the like, and then a deflection yoke (not shown). ), And deflects into a fluorescent screen (not shown) formed on the inner surface of the panel portion of the cathode ray tube,
The light is emitted to form an image.

[0005]

Since the conventional electron gun is configured as described above, it has the following problems. That is, the electron gun is accommodated in the neck portion 10 with its central axis coinciding with the central axis of the neck portion 10, and the bead glass 7 extends parallel to the central axis of the electron gun. The distance between the outer surface of the glass 7 and the inner wall surface of the neck portion 10 is the same in each portion. As an example, in the case of a cathode ray tube having an inner diameter of the neck portion 24.1 mm,
The distance between the outer surface of the bead glass 7 and the inner wall surface of the neck portion 10 is 1.0 mm in each portion. However, since the metal wire 9 is disposed on the second grid electrode 4 so as to surround the outer surface of the bead glass 7 and to be interposed between the second grid electrode 4 and the inner wall surface of the neck portion 10, the metal wire 9 and the neck portion 10 are disposed. Is smaller than the distance between the outer surface of the bead glass 7 and the inner wall surface of the neck portion 10 in other portions, and when a metal wire 9 having a wire diameter of 0.4 mm is used, The distance between the metal wire 9 and the inner wall surface of the neck 10 is 0.6 mm. Therefore, in the spot knocking process which is a manufacturing process of a cathode ray tube for applying a high voltage pulse to the anode electrode 6 by grounding the third grid electrode 5 and each electrode on the cathode electrode 1 side therefrom,
The discharge between the metal wire 9 and the inner wall surface of the neck portion 10 is strong, and there is a problem that the discharge causes a crack in the neck portion 10.

In the step of heating the metal wire 9 by high frequency heating or the like to form a metal deposition film on the inner wall surface of the neck portion 10, the heated metal wire 9 expands as shown by the broken line in FIG. Contact the inner wall surface of the neck part 10
There has been a problem that cracks occur in the neck portion 10.

In order to solve the problem of cracks in the neck portion 10 due to the presence of the metal wire 9, the outer diameter of the electron gun can be reduced as a whole to increase the distance between the outer surface of the bead glass 7 and the inner wall surface of the neck portion 10. However, since it is necessary to reduce the outer diameter of each electrode, the diameter of the electron lens formed between the third grid electrode 5 for focusing the electron beam and the anode electrode 6 is particularly small, and the aberration is small. Since the number of electron beams becomes large, the diameter of the electron beam focused on the phosphor screen of the cathode ray tube becomes large, which causes deterioration of image quality.

It is conceivable to provide a groove on the outer surface of the bead glass 7 for accommodating the metal wire 9 so that the metal wire 9 does not protrude from the outer surface of the bead glass 7. In the process of embedding the strap portions 8 of the electrodes 5 and 6 and the ends of the electrodes 3 and 4 in the bead glass 7, there is a problem that cracks are generated in the groove portions of the bead glass 7. Also,
The grooved bead glass 7 is liable to be distorted in the groove due to the embedding, and has a problem that the groove is cracked when the metal wire 9 is heated at a high frequency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can secure a necessary distance from the inner surface of a neck portion without deteriorating the electron lens characteristics of an electron gun. It is an object of the present invention to obtain an electron gun for a cathode ray tube which can prevent a neck portion and a crack of a bead glass from occurring in the manufacturing process.

[0010]

An electron gun for a cathode ray tube according to the present invention is arranged around each electrode sequentially arranged in the direction of emission of an electron beam and extends in the direction of the central axis of the electron gun. A plurality of electrically insulating supporting rods to be fixed are inclined with respect to the center axis of the electron gun so that the distance between the cathode electrode tube and the inner surface of the neck portion of the cathode ray tube is larger on the cathode electrode side than on the anode electrode side. is there. Further, it has a conductive lead fixed to the grid electrode and disposed so as to surround the outer surface of the electrically insulating support rod and to be interposed between the inner surface of the neck portion.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a diagram showing an electron gun for a cathode ray tube according to a first embodiment of the present invention, and FIG. 2 is a diagram showing a partially enlarged view. In the figure, reference numeral 1 denotes a cathode electrode, which is heated by a heater 2 and emits an electron beam. Reference numeral 3 denotes a cup-shaped first grid electrode for controlling an electron beam emitted from the cathode electrode 1, 4 denotes a plate-shaped second grid electrode for accelerating the electron beam controlled by the first grid electrode 3, and 5 denotes a second grid electrode. A cylindrical third grid electrode 6 for converging the electron beam accelerated by the grid electrode 4, a cylindrical anode electrode 6 electrically connected to an anode for supplying a high voltage of a cathode ray tube, 3, 4, 5 and 6 are sequentially arranged in the emission direction of the electron beam with their central axes aligned.

Reference numeral 7 denotes a pair of bead glasses which are electrically insulating supporting rods which are arranged around the electrodes 1, 3, 4, 5 and 6 and extend in the direction of the central axis, that is, the central axis of the electron gun. By embedding the ends of the strap portions 8 or the electrodes 3 and 4 implanted in 5, 6 into the bead glass 7,
The electrodes 3, 4, 5, and 6 are fixed and held in a predetermined positional relationship. Reference numeral 9 denotes a metal wire that is a conductive lead fixed at both ends to the second grid electrode 4 and disposed so as to surround the outer surface of the bead glass 7 and to be interposed between the second grid electrode 4 and the inner wall surface of the neck portion 10. This is provided so that discharge due to electric charges accumulated on the outer surface of the glass 7 does not occur on the cathode electrode 1 side with respect to the second grid electrode 4. The electron gun having such a configuration is housed and held in the neck portion 10 with its central axis coinciding with the central axis of the neck portion 10. Reference numeral 11 denotes a cup electrode fixed to the anode electrode 6, and 12 denotes a spring attached to the cup electrode 11, which presses against the inner wall surface of the neck 10 when the electron gun is inserted into the neck 10. Thereby, the electron gun is supported and fixed in the neck portion 10.

The bead glass 7 of the first embodiment is parallel to the center axis of the electron gun in the conventional example shown in FIG. Are also inclined with respect to the center axis of the electron gun so that the cathode electrode 1 side becomes larger. Specifically, the inner diameter of the neck portion 10 is 24.1 mm, the wire diameter of the metal wire 9 is 0.4 mm, and the outer surface of the bead glass 7 near the strap portion 8 of the anode electrode 6 and the inner wall surface of the neck portion 10 The distance between the outer surface of the bead glass 7 and the inner wall surface of the neck 10 at the second grid electrode 4 is 1.225 mm, that is, the metal wire 9 and the neck 1
0 is inclined so that the distance from the inner wall surface is 0.825 mm. The cross-sectional shape of the bead glass 7 is a substantially rectangular shape having a side of 7 mm on the side where the strap portion 8 is embedded and a side of 3 mm orthogonal to the side.

After the electron gun having such a structure is housed and fixed in the neck portion 10 and the inside of the cathode ray tube is evacuated to a vacuum,
The metal wire 9 is heated and evaporated by high frequency heating or the like,
As shown in FIG. 2, the metal deposition film 1 is formed on the inner wall surface of the neck 10.
Form 3 Thereafter, the cathode ray tube is completed through a spot knocking step of applying a high-voltage pulse, an aging step for facilitating the emission of electrons from the cathode electrode 1, and the like.

According to the electron gun having such a configuration, the distance between the bead glass 7 and the inner surface of the neck portion 10 is determined by the third grid electrode 5 and the anode electrode which determine the diameter of the electron lens for focusing the electron beam. Since the bead glass 7 is tilted with respect to the center axis of the electron gun so that the cathode electrode 1 side, which has less influence on the outer diameter of the cathode electrode 6, is larger than the anode electrode 6, the diameter of the electron lens can be reduced. The distance between the metal wire 9 and the inner wall surface of the neck portion 10 can be set to a required size without providing a groove for accommodating the metal wire 9 in the bead glass 7. Therefore, the discharge between the metal wire 9 and the inner wall surface of the neck portion 10 in the spot knocking step is weakened, and the problem that the neck portion 10 is cracked by this discharge is prevented.

In the step of heating the metal wire 9 by high frequency heating or the like to form the metal deposition film 13 on the inner wall surface of the neck portion 10, the metal wire 9 expanded by heating comes into contact with the inner wall surface of the neck portion 10. The problem that cracks occur in the neck portion 10 due to this contact can also be improved. FIG. 3 is a diagram showing the rate of occurrence of neck cracks during high-frequency heating of the metal wire 9, and the “wire-neck inner wall clearance” on the horizontal axis indicates the metal wire 9.
And the inner wall surface of the neck portion 10. When the distance between the metal wire 9 and the inner wall surface of the neck portion 10 is 0.4 mm, the crack occurrence rate is 10.0%, and when it is 0.6 mm, it is 3.5%. Then 0.0
%Met.

Although the case where the number of the bead glasses 7 is two has been described, it goes without saying that the same effect can be obtained when the number of the bead glasses 7 is three or more. Further, even when the metal wire 9 is heated by high-frequency heating or the like and the metal deposition film 13 is not formed on the inner wall surface of the neck portion 10, the effect of preventing the crack from occurring in the neck portion 10 due to the discharge in the spot knocking process can be obtained. Is similar. Also, the metal wire 9
Is fixed to the second grid electrode 4, but
It is needless to say that the same method can be applied to the case of fixing to the first grid electrode 3 or the third grid electrode 5.

[0018]

According to the electron gun for a cathode ray tube according to the present invention, the electrodes are arranged around the electrodes sequentially arranged in the emission direction of the electron beam, extend in the direction of the central axis of the electron gun, and fix the electrodes. Since the plurality of electrically insulating support rods were inclined with respect to the center axis of the electron gun so that the distance between the cathode electrode side and the inner surface of the neck portion of the cathode ray tube was larger on the cathode electrode side than on the anode electrode side, the grid electrode was The distance between the conductive lead, which is fixed to the outer surface of the electrically insulating support rod and surrounds the inner surface of the neck, and the inner surface of the neck, deteriorates the electron lens characteristics of the electron gun. It is possible to prevent the occurrence of cracks in the neck portion and the electrically insulating support rod in the manufacturing process of the cathode ray tube.

[Brief description of the drawings]

FIG. 1 is a view showing an electron gun for a cathode ray tube according to a first embodiment of the present invention.

FIG. 2 is an enlarged view showing a part of a cathode ray tube electron gun according to Embodiment 1 of the present invention;

FIG. 3 is a diagram showing a neck crack occurrence rate during high frequency heating of a metal wire.

FIG. 4 is a view showing a conventional electron gun for a cathode ray tube.

FIG. 5 is a partially enlarged view for explaining inconvenience of a conventional electron gun for a cathode ray tube.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cathode electrode, 3 1st grid electrode, 4 2nd grid electrode, 5 3rd grid electrode, 6 Anode electrode, 7 Bead glass, 9 Metal wire, 10
Neck

Claims (2)

[Claims] A cathode electrode for emitting an electron beam;
A plurality of grid electrodes and an anode electrode are sequentially arranged in the direction of emission of the electron beam with their central axes aligned, and a plurality of electrically insulating support rods are arranged around these electrodes and extend in the central axis direction. In the electron gun in which each of the electrodes is fixed and housed in the neck of the cathode ray tube, each of the electrically insulating supporting rods is arranged such that the interval between the inner surface of the neck and the cathode is closer to the cathode than the anode. The electron gun for a cathode ray tube, characterized in that the electron gun is inclined with respect to the central axis so as to be larger. 2. A conductive lead fixed to a grid electrode and disposed so as to surround the outer surface of the electrically insulating support rod and to be interposed between the inner surface of the neck portion and the conductive lead. The electron gun for a cathode ray tube according to the above.