JPH07147144A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To stabilize the potential on the inner wall of a neck glass, and suppress the discharge in a neck part. CONSTITUTION:A conductive wire rod 7 is set in the center of a fourth grid electrode 11 which is a focusing electrode so as to surround the outer surface of a bead glass 8. An arc shield 9 is set to surround the minor diameter part of a third grid electrode 12, and the skirt part 9a of the arc shield 9 is set to the length reaching a second grid electrode 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube of a so-called trinitron type color television using a unipotential type electron gun.

[0002]

2. Description of the Related Art A neck portion of a picture tube of a color television, to which an electron gun is fixed, and a bead glass which supports each electrode constituting the electron gun are insulators and have a secondary electron emission ratio of 1.
That is all. Therefore, if electrons hit the inner wall of the neck glass or the surface of the bead glass in the neck portion for some reason, more electrons are emitted, and the potential of the inner wall of the neck glass or the surface of the bead glass rises. This makes it easier for electrons to hit the inner wall of the neck glass and the surface of the bead glass, and further raises the potential of the inner wall of the neck glass and the surface of the bead glass. In this way, when the potential of the inner wall of the neck glass or the surface of the bead glass rises, high voltage enters the low voltage electrode side, discharge occurs between the inner wall of the neck glass or the surface of the bead glass and the low voltage electrode, and the image is disturbed. And damage to the semiconductor element of the device incorporating the picture tube.

Therefore, in order to suppress the generation of such an electric discharge, a metal is vapor-deposited on the inner wall of the neck corresponding to the low-voltage electrode, as shown in JP-A-58-32337 and JP-A-58-106855. However, it is known that this reduces the secondary electron emission ratio, suppresses the rise in the potential of the inner wall of the neck, and prevents discharge. In this case, a metal wire to be vapor-deposited, for example, a pure nickel wire is installed in advance on the low-voltage electrode so as to straddle the bead glass. Are scattered and deposited on the inner wall of the neck.

[0004]

By the way, in a cathode ray tube of a so-called trinitron type color television using a unipotential type electron gun, an electrode having a voltage lower than these high voltage electrodes is provided between two high voltage electrodes. Exist, and the high-voltage electrode and the low-voltage electrode are adjacent to each other. Therefore, it is desired to stabilize the potential between these electrodes and suppress the discharge.

In view of the above situation, the present invention provides a cathode ray tube capable of stabilizing the potential between electrodes and suppressing discharge.

[0006]

A cathode ray tube according to the present invention includes two high voltage electrodes, an intermediate voltage electrode sandwiched between the two high voltage electrodes, and one of the two high voltage electrodes on the high voltage electrode side. In a cathode ray tube having a low-voltage electrode arranged in, a bead glass holding each of the electrodes, and a neck portion in which the electrodes and the bead glass are built in, the bead to the medium-voltage electrode The above-mentioned problems are solved by disposing a conductive wire material so as to surround the outer surface of glass and forming a vapor deposition film on the inner wall of the neck portion.

The above-mentioned problems can be solved by disposing an arc shield having a skirt portion reaching the low voltage electrode between the high voltage electrode and the low voltage electrode arranged on the high voltage electrode side.

Here, the intermediate voltage electrode is a focus electrode.

[0009]

In the present invention, a conductive wire is arranged on a medium voltage electrode sandwiched between two high voltage electrodes to form a vapor deposition film, and an arc shield having a skirt portion reaching the low voltage electrode is arranged on the high voltage electrode. By doing so, the potential inside the cathode ray tube is stabilized and discharge is suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. 1, according to the present invention,
1 shows a schematic configuration of a cathode ray tube which is a neck portion of a picture tube. 1A is a cross-sectional view of the cathode ray tube viewed from the bead glass side, and FIG. 1B is a cross-sectional view of the cathode ray tube viewed from the high-voltage connector side.

Inside the neck glass 1 of the neck portion shown in FIG. 1, a unipotential type electron gun is arranged. This electron gun has a first grid electrode 1 which is a low voltage electrode.
4 and a second grid electrode 13, a third grid electrode 12 which is a high voltage electrode, a fourth grid electrode 11 which is a medium voltage electrode, and a fifth electrode 10 which is a high voltage electrode.

For example, specifically, a voltage of 200 V is applied to the first grid electrode 14 and a voltage of 500 V is applied to the second grid electrode 13. In addition, the third grid electrode 12, the fourth grid electrode 11, and the fifth
The grid electrode 10 constitutes a focusing electrode. A support spring 2 is connected to the fifth grid electrode 10, and a voltage of, for example, 30 kV is applied from the internal conductive film 3 formed on the inner wall of the neck glass 1 through the support spring 2. Further, since the fifth grid electrode 10 and the third grid electrode 12 are connected by the high voltage connector 4, the same voltage is applied to the fifth grid electrode 10 and the third grid electrode 12. The fourth grid electrode 11 is a focus electrode, is connected to the stem pin 6 by the fourth grid electrode lead 5, and is applied with a voltage of 6 kV, for example.

Here, FIG. 2 showing a partial structure of the cathode ray tube.
The discharge will be described in detail with reference to. For example, when there are scratches, burrs, dust, and the like on the fourth grid electrode 11 having a medium pressure, electrons are emitted due to the electric field concentration. When the emitted electrons hit the inner wall of the neck glass 1 or the bead glass 8 which is an insulator, the collision energy causes the neck glass 1 and the bead glass 8 to emit light. This is called stray. At this time, if more electrons than the number of input electrons are emitted from the surface of the neck glass 1 or the bead glass 8 (secondary electron emission), the portion of the neck glass 1 or the bead glass 8 from which the electrons are emitted becomes It becomes positively charged. As a result, the positively charged portions of the neck glass 1 and the bead glass 8 more and more pull electrons from the fourth grid electrode 11, and thus stray grows. When the stray exceeds a certain limit point, the charge flows along the surface of the neck glass 1. As a result, the exterior capacitance Q flows to the stem pin 6 side (ground side) in FIG. This phenomenon is called discharge.

In order to suppress this discharge, a conductive wire 7 made of, for example, an alloy of nickel and manganese is installed at the center of the fourth grid electrode 11 so as to surround the outer surface of the bead glass 8. This is the fourth grid electrode 1
1 has a long total length, and the fourth grid electrode 11 utilizes that the influence of high voltage due to the high voltage of the third grid electrode 12 and the fifth grid electrode 10 is small.

FIG. 3 shows the relationship between the voltage and the potential on the inner wall of the neck of the neck glass 1. The high voltage side of FIG. 3 is the fifth grid electrode 10, and the medium pressure side is the fourth grid electrode 11. In addition, the broken line a in FIG. 3 indicates the potential when the conductive wire 7 is not installed on the fourth grid electrode 11, and the solid line b indicates the potential when the conductive wire 7 is installed on the fourth grid electrode 11. Indicates. As described above, when the conductive wire 7 is installed, the discharge is suppressed more than when the conductive wire 7 is not installed, so that the potential is lowered in the range x ₁ . Also, the range x in FIG.
Reference numeral ₂ is a portion where the above-mentioned conductive wire 7 is vapor-deposited, and the potential is stable in this portion.

Next, FIG. 4 shows a sectional view of the fourth grid electrode 11 when the cathode ray tube shown in FIG. 1 is heated by a high frequency heating device. The conductive wire 7 is heated and evaporated by a high frequency heating device, and the vapor deposition film 2 is formed on the inner wall of the neck glass 1.
0 is formed. By forming this vapor deposition film 20, the potential on the inner wall of the neck glass 1 and the surface of the bead glass 8 is stabilized. In addition, the third grid electrode 12
And the discharge from the high voltage of the fifth grid electrode 10 to the fourth grid electrode 11 of a medium voltage lower than those electrodes, and the fourth of the medium voltage from the inner wall of the neck glass 1 where the high potential electric field is extended. The discharge to the grid electrode 11 is suppressed.

Next, FIG. 5 shows a sectional view of the arc shield 9 of the cathode ray tube according to the present invention. The arc shield 9 of FIG. 5 is ring-shaped and has the third grid electrode 1 described above.
It is installed so as to surround the small diameter portion of 2. The skirt portion 9a of the arc shield 9 is set to have a length up to the second grid electrode 13. Further, the same voltage as that of the fourth grid electrode 11 is applied to the arc shield 9. As a result, discharge from the high voltage of the third grid electrode 12 to the low voltage of the second grid electrode 13 and the like, and from the inner wall of the neck glass 1 where the high potential electric field is expanding to the low voltage second grid electrode 13 Discharge is suppressed.

[0018]

As is apparent from the above description, in the cathode ray tube according to the present invention, the conductive wire is arranged around the outer surface of the bead glass in the intermediate pressure electrode which is the focus electrode, and the By forming the vapor deposition film on the inner wall, the potential of the inner wall of the neck glass can be stabilized. This also stabilizes the potential inside the neck,
Discharge can be suppressed.

Further, by disposing an arc shield having a skirt portion reaching the low voltage electrode between the high voltage electrode and the low voltage electrode arranged on the high voltage electrode side,
The potential of the inner wall of the neck glass can be stabilized. Further, this stabilizes the potential inside the neck portion and suppresses discharge.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a cathode ray tube according to the present invention.

FIG. 2 is a diagram showing a schematic configuration of a part of the cathode ray tube of FIG.

FIG. 3 is a diagram showing a relationship between a voltage and a potential of an inner wall of the neck.

4 is a cross-sectional view of a conductive wire rod of the cathode ray tube of FIG.

5 is a cross-sectional view of the arc shield of the cathode ray tube of FIG.

[Explanation of symbols]

 1 ... Neck glass 2 ... Support spring 3 ... Internal conductive film 4 ... High-voltage connector 6 ... Stem pin 7 ... Conductive wire 8 ... Bead glass 9 ... Arc shield 10 ... 5th grid electrode 11 ... 4th grid electrode 12 ... 3rd grid electrode 13 ... 2nd grid Electrode 14 ... First grid electrode

Claims (3)

[Claims] 1. A high-voltage electrode, a medium-voltage electrode sandwiched between the two high-voltage electrodes, a low-voltage electrode disposed on the high-voltage electrode side of one of the two high-voltage electrodes, and each of the electrodes. In a cathode ray tube having a bead glass to be held and a neck portion in which each of the electrodes and the bead glass is built, a conductive wire is arranged so as to surround the outer surface of the bead glass with respect to the intermediate voltage electrode. A cathode ray tube, characterized in that a vapor deposition film is formed on the inner wall of the neck portion. 2. An arc shield having a skirt portion reaching the low-voltage electrode is arranged between the high-voltage electrode and the low-voltage electrode arranged on the high-voltage electrode side. Cathode ray tube. 3. The cathode ray tube according to claim 1, wherein the medium voltage electrode is a focus electrode.