JPH05242829A - Cathode ray tube - Google Patents

Abstract

(57) [Summary] [Structure] An envelope 4 including a face portion 2 and a funnel-shaped funnel 3 is provided, and an inner surface of the funnel is connected to an anode terminal 10 provided on a side surface of the funnel to form a conductive film.
In the cathode ray tube in which 23 is coated and formed, and the inner tube members 14, 15, 16 arranged in the envelope are pressed against the conductive film, at least the portions 25C, 25G, 25S of the conductive film which are in pressure contact with the inner member.
Was formed of a conductive coating mainly composed of graphite, non-magnetic iron oxide and silicate. [Effect] It is possible to prevent deterioration of withstand voltage characteristics due to the influence of magnetism applied from the outside of the cathode ray tube.

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 such as a color picture tube, and more particularly to a cathode ray tube which prevents deterioration of withstand voltage characteristics due to the dropping of a conductive film formed by coating on the inner surface of its funnel.

[0002]

2. Description of the Related Art Generally, a cathode ray tube has a structure for displaying an image by scanning a phosphor screen formed on an inner surface of a face portion with an electron beam emitted from an electron gun.

As an example thereof, FIG. 3 shows a color picture tube. This color picture tube has an envelope 4 composed of a panel 2 (face part) having a skirt portion 1 provided on the periphery and a funnel-shaped funnel 3 integrally joined to the skirt portion 1.
Have. A phosphor screen 5 composed of a three-color phosphor layer is formed on the inner surface of the face portion 2, and a shadow mask 6 facing the phosphor screen 5 and having a large number of electron beam passage holes formed therein is formed. The panel 2 is mounted by a mask supporting means including a stud pin 7 provided on the inner surface of the skirt portion 1 and a frame holder 8 attached to the shadow mask 6. On the other hand, the large-diameter part 9 of the funnel 3 is provided with the anode terminal 10, and
An internal conductive film 12 is formed by coating from the inner surface of 9 to the inner surface of the adjacent portion of the neck 11. Further, an electron gun 13 composed of a plurality of electrodes is arranged in the neck 11, and an internal conductive film on the inner surface of the large diameter portion 9 is attached to the electrode of the electron gun 13 on the phosphor screen 5 side.
A getter 14 that presses against 12 is attached.

In the color picture tube having such a structure, the anode high voltage applied to the anode terminal 8 provided in the large-diameter portion 7 of the funnel 3 is applied to the shadow mask 6 and the phosphor screen 5 via the shadow mask 6. In order to apply the voltage to the inner surface of the funnel 3, the shadow mask 6 is applied to the inner conductive film 12 formed on the inner surface of the large-diameter portion 7 of the elastic body.
The F connector 15 is also the phosphor screen 5 of the electron gun 13.
The electrode on the side supports the phosphor screen 5 side of the electron gun 13 and applies an anode high voltage to the final accelerating electrode on the phosphor screen 5 side. A valve spacer 16 made of an elastic body that is in pressure contact with 12 is attached.

By the way, when the inner conductive film 12 is pressed against the inner film members such as the getter 14, the PF connector 15 and the valve spacer 16 as described above, an external shock or vibration is applied when the color picture tube is transported. In this case, there is a problem that the inner conductive film 12 at the pressure contact portion is rubbed and falls off.

That is, the conventional internal conductive film 12 uses graphite as a conductive material, and magnetic iron oxide or titanium oxide as a specific resistance adjusting material, and an alkali silicate (water glass) such as sodium silicate or potassium silicate as a binding material. Since it is formed by applying a mixed liquid containing the above, its adhesion strength is not so high. Therefore, when external shock or vibration is applied to the color picture tube, the getter 14, the PF connector 15 and the valve spacer 15 are pressed against each other. The inner conductive film 12 at the pressure contact portion is rubbed off by being rubbed by a member inside the tube such as 16. Then, the dropped particles cause discharge during operation of the color picture tube, and deteriorate the characteristics of the color picture tube.

In order to prevent the internal conductive film 12 from falling off, it is sufficient to increase the amount of alkali silicate added as a binder to increase the adhesion strength. However, if the amount of alkali silicate added is increased, Along with this, the amount of gas released increases, which lowers the degree of vacuum in the tube and deteriorates the characteristics of the color picture tube. That is, there is a limit to the increase in the amount of addition of the alkali silicate, and it is difficult to prevent the internal conductive film 12 from falling off by this method.

In recent years, color cathode-ray tubes tend to have a higher anode high voltage applied to them for higher brightness. In order to improve focus characteristics, a color picture tube using an electron gun in which some electrodes are made of a magnetic material has been developed. In such a color picture tube, when a mixed solution containing magnetic iron oxide is applied as the specific resistance adjusting material to form the internal conductive film 12, the magnetic iron oxide is contained in the particles that have fallen off, and the external part of the color picture tube is removed. Influence of the magnetic field applied from, for example, demagnetization during adjustment of the color picture tube, magnetic field generated by the deflection yoke during the operation of the color picture tube, and purity
It may move in the tube due to changes in the magnetic field during adjustment of the convergence magnet, which may cause electric discharge. Furthermore, in a color picture tube that uses an electron gun in which an electrode is formed of a magnetic material, fallen particles containing magnetic iron oxide gather at the magnetic electrode,
There is a problem that deterioration of withstand voltage characteristics such as discharge is more likely to occur than in a normal color picture tube.

[0009]

As described above, in the color picture tube, the inner conductive film is formed by coating on the inner surface of the funnel, and the getter attached to the electrode on the phosphor screen side of the electron gun is formed on the inner conductive film. In-tube members such as a PF connector attached to the shadow mask and a valve spacer attached to the electrode on the phosphor screen side of the electron gun are in pressure contact with each other. However, when internal members such as getters, PF connectors, valve spacers, etc. are pressed into contact with each other in this manner, the conventional internal conductive film uses graphite as a conductive material, and magnetic iron oxide or titanium oxide as a specific resistance adjusting material or a binding material. Since it is formed by applying a mixed liquid containing an alkali silicate, its adhesion strength is not so high, and the getter and PF are pressed against each other by an external shock or vibration applied to the color picture tube.
The inner conductive film at the pressure-contacted portion is removed by being rubbed by a member inside the tube such as a connector or a valve spacer.

In particular, in recent years, in a color picture tube, the anode high voltage applied to the color picture tube has become higher in order to increase the brightness.
In addition, in order to improve the focus characteristics, a color picture tube using an electron gun in which some electrodes are made of a magnetic material has been developed, and such a color picture tube contains a liquid mixture containing magnetic iron oxide as a resistivity adjusting material. When the internal conductive film is formed by coating with, the iron oxide particles are contained in the falling particles, and the falling particles containing the magnetic iron oxide move inside the tube due to the effect of the magnetic field applied from the outside of the color picture tube, causing the discharge. Becomes Furthermore, in a color picture tube that uses an electron gun in which electrodes are made of a magnetic material, fallen particles containing magnetic iron oxide collect on the electrodes made of the magnetic material, and deterioration of withstand voltage characteristics such as electric discharge occurs in a normal color picture tube. There is a problem that it is more likely to occur.

The present invention has been made in view of the above problems, and even if the inner conductive film formed by coating on the inner surface of the funnel is rubbed off by the inner member pressed against the inner conductive film, the inner conductive film is external to the cathode ray tube. The purpose is to prevent the deterioration of the withstand voltage characteristics from being accelerated by the influence of the magnetic field applied from the.

[0012]

A face portion and a funnel-shaped outer envelope are formed, and an inner surface of the funnel is connected to an anode terminal provided on a side surface of the funnel to form a conductive film by coating. In a cathode ray tube in which an inner tube member disposed in an envelope is in pressure contact with this conductive film, at least a portion of the conductive film in which the inner tube member is in pressure contact is made of a conductive material containing graphite, nonmagnetic iron oxide, and silicate as main components. Formed of a film.

[0013]

As described above, when at least a portion of the conductive film formed by coating on the inner surface of the funnel, which is brought into pressure contact with the inner member of the tube, is formed of a conductive film containing graphite, non-magnetic iron oxide and silicate as main components, for example, Even if the pressure contact part with the tube inner member is rubbed and dropped due to external vibration or shock, the dropped particles are non-magnetic, so the influence of the magnetic field applied to the cathode ray tube from the outside can be eliminated, and It is possible to prevent the deterioration of withstand voltage characteristics caused by the falling particles containing the magnetic material.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 1 shows a color picture tube which is an embodiment of the present invention. This color picture tube has an envelope 4 composed of a panel 2 having a skirt portion 1 provided in the peripheral portion thereof and a funnel-shaped funnel 3 integrally joined to the skirt portion 1.
On the inner surface of the panel 2, there is formed a phosphor screen 5 composed of a three-color phosphor layer that emits blue, green and red, facing the phosphor screen 5 and shadow mask inside thereof.
6 are arranged. This shadow mask 6 is composed of a mask body 20 having a large number of electron beam passage holes and a mask frame 21 attached to the peripheral portion of the mask body 20, and is provided on the inner surface of the skirt portion 1 of the panel 2. Stud pin 7 and a frame holder attached to the side of the mask frame 21 and locked to the stud pin 7
It is attached to the inside of the panel 2 by the mask supporting means consisting of 8 and.

On the other hand, in the neck 11 of the funnel 3, an electron gun 13 composed of a plurality of electrodes is arranged. An anode terminal 10 is provided on the large-diameter portion 9 of the funnel 3, and an internal conductive film 23 connected to the anode terminal 10 is formed by coating from the inner surface of the large-diameter portion 9 to the inner surface of the adjacent portion of the neck 11. There is.

The mask frame 21 has a large diameter of the funnel 3 for applying an anode high voltage applied to the anode terminal 10 to the shadow mask 6 and the phosphor screen 5 via the shadow mask 6. The PF connector 15 made of an elastic body that comes into pressure contact with the internal conductive film 23 on the inner surface of the portion 9
However, the electrode on the phosphor screen 5 side of the electron gun 13
In order to support the electron gun 13 on the phosphor screen 5 side and to supply the anode high voltage applied to the anode terminal 10 to the final accelerating electrode on the phosphor screen 5 side, an internal coating formed on the inner surface of the neck 11 is formed. A valve spacer 16 made of a plurality of elastic bodies is provided in pressure contact with the conductive film 23. Further, a getter 14 that is in pressure contact with the internal conductive film 23 on the inner surface of the large-diameter portion 9 of the funnel 3 is attached to the electrode of the electron gun 13 on the phosphor screen 5 side via an elastic support 24.

By the way, the internal conductive film of this color picture tube
As shown in FIG. 2, 23 is a portion 25C where the pipe members such as the PF connector, the valve spacer, and the getter 14 are in pressure contact with each other.
The parts 26 other than 25S, 25S and 25G are made of graphite as a conductive material similar to the conventional internal conductive film, and magnetic iron oxide or titanium oxide is used as a resistivity adjusting material, and alkali silicate such as sodium silicate or potassium silicate is used as a binding material. It is formed by applying a mixed solution containing salt (water glass), but the parts 25C, 25S, 25G where the pipe members such as the PF connector 15, valve spacer 16 and getter 14 are in pressure contact are made of graphite as a conductive material. It is formed by applying a non-magnetic α-ferric oxide as a resistivity adjusting material and the above-mentioned alkali silicate as a binding material.

As for the internal conductive film 23 formed by coating on the inner surface of the funnel 3 as described above, at least a portion of the inner tube member such as the PF connector 15, the valve spacer 16 and the getter 14 which is pressure-contacted with the conductive film containing no magnetic material. Then,
Even if the internal particles such as the PF connector 15, valve spacer 16 and getter 14 scrub and fall off due to external shock or vibration applied to the color picture tube, the fallen particles do not contain a magnetic material, so the color image is received from the outside. Move inside the tube due to the influence of the magnetic field applied to the tube, such as demagnetization during adjustment of the color picture tube, magnetic field generated by the deflection yoke during operation of the color picture tube, or change in the magnetic field during adjustment operation of the purity convergence magnet. Also, even in a color picture tube in which some electrodes of the electron gun are made of a magnetic material, the fallen particles do not collect at the electrodes made of the magnetic material, so there is no deterioration in withstand voltage characteristics such as discharge. A stable color picture tube can be obtained.

In the above embodiment, the PF connector,
Only the portion of the valve spacers, getters, etc. where the inner members are in pressure contact was formed by applying a mixed solution containing non-magnetic α-ferric oxide, but the inner conductive film formed on the inner surface of the funnel was all non-magnetic. You may form by the mixed liquid which added the (alpha)-ferric oxide.

Although the above embodiment has been described with respect to the color picture tube, the present invention can be applied to a cathode ray tube other than the color picture tube to obtain the same effect.

[0022]

EFFECTS OF THE INVENTION If at least the portion of the conductive film formed by coating on the inner surface of the funnel which is in pressure contact with the inner member of the tube is made of a conductive film containing graphite, non-magnetic iron oxide and silicate as the main components, for example, external impact or Even if the pressure contact part with the tube inner member is rubbed and dropped due to vibration, etc., the fallen particles do not contain a magnetic material, so it is possible to eliminate the influence of magnetism applied to the cathode ray tube from the outside, and the fallen from the conventional conductive film. It is possible to prevent the deterioration of the withstand voltage characteristic caused by the particles being a magnetic substance, and to provide a cathode ray tube with a stable withstand voltage characteristic.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a color picture tube which is an embodiment of the present invention.

FIG. 2 (a) is a plan view showing the funnel, and FIG. 2 (b) is a front view showing a section thereof.

FIG. 3 is a diagram showing a configuration of a conventional color picture tube.

[Explanation of symbols]

 2… Panel 3… Funnel 4… Enclosure 5… Phosphor screen 6… Shadow mask 7… Stud pin 8… Frame holder 9… Large diameter part 10… Anode terminal 11… Neck 13… Electron gun 14… Getter 15… PF Connector 16 ... Valve spacer 23 ... Internal conductive film 25C ... PF Internal conductive film at the portion where the connector is pressed 25G ... Internal conductive film at the portion where the getter is pressed 25S ... Internal conductive film where the valve spacer is pressed

Claims (1)

[Claims] 1. An envelope having a face portion and a funnel-shaped funnel, wherein an inner surface of the funnel is connected to an anode terminal provided on a side surface of the funnel to form a conductive film by coating. In the cathode ray tube in which the inner tube member disposed in the envelope is in pressure contact, the conductive film is composed of at least a portion in which the inner tube member is in pressure contact from a conductive film containing graphite, non-magnetic iron oxide and silicate as a main component. A cathode ray tube characterized in that