JPH10334798A - Arc suppressor forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give resistance distribution to an arc suppressor formed in bead glass used when an electron gun body structure is assembled to prevent dielectric breakdown caused by electric field concentration. SOLUTION: In order to assemble an electron gun 6 mounted on a neck part 4 of a cathode-ray tube, when a plurality of electrode components G1-G4 arranged in the axial direction with a pair of supporting members comprising bead glasses 11, 12 are held, a conductive region 15 is formed in each of the bead glasses 11, 12 to form an arc suppressor for suppressing discharge within the tube. Conductive paste 15P is applied in the specified pattern to parts of the back surface 11b and the side surface 11s continuing from the back surface 11b of the bead glass 11 facing the neck part 4, and the coating amount per area of the conductive paste 15P is gradually decreased from the inside of the pattern toward the periphery part in the axial direction. The conductive paste 15P is baked at the specified temperature, diffused according to the coating amount into the beads glasses 11, 12, and the conductive region 15 where the resistance value is gradually increased from the inside to the periphery part in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for forming an arc suppressor for suppressing discharge in a tube of an electron gun mounted on a neck portion of a cathode ray tube.

[0002]

2. Description of the Related Art FIG. 6 shows a general structure of a cathode ray tube.
The funnel 1 has interior carbon 2 on the inner surface. An anode voltage is supplied to the interior carbon 2 from the outside via the anode pattern 3. The neck 4 is located at the rear of the funnel 1. The neck 4 is directed forward by the electron beam 5.
An electron gun 6 that emits light is stored. A panel 7 is attached to the front of the funnel 1, and a fluorescent screen 8 on which the electron beam 5 is incident is provided. When the heater of the electron gun 6 is heated, thermoelectrons are emitted from the cathode electrode. The electron gun 6 includes a control electrode (control grid) G1.
Controls thermoelectrons. Further, it includes an acceleration electrode (screen grid) G2 and attracts thermoelectrons in the direction of the fluorescent screen 8. The thermoelectrons that have passed through the acceleration electrode G2 are further focused by the focus electrode G3, accelerated by the anode electrode G4, and irradiated on the phosphor screen 8 as the electron beam 5. For this reason, on the fluorescent screen 8, the portion irradiated with the electron beam 5 becomes a spot and shines brightly. In the case of a color cathode ray tube, the electron beam 5 is applied to the phosphor screen 8 via a color selection mask 9 such as an aperture grill or a shadow mask.

FIG. 7 schematically shows an assembly structure of the electron gun 6. In order to assemble the electron gun 6 mounted on the neck of the cathode ray tube, a plurality of electrode components G1 to G4 arranged in the axial direction are held and fixed using a pair of support members made of bead glasses 11 and 12. Specifically, the electrode component G1
~ G4 is set in the positioning jig, and bead glass 1
The electrode component G1 is heated and softened by a burner.
To G4 to assemble the electron gun 6. This step is called beading.

[0004]

Conventionally, there has been known an arc suppressor forming method in which conductive regions are provided in the bead glasses 11 and 12 to suppress discharge in the tube.
No. 5,26,486. According to this, the cathode ray tube includes a vacuum envelope (funnel) having an electrically insulating neck portion, and an electron gun structure disposed in the neck portion and close to an inner surface thereof. The electron gun assembly includes a plurality of electrode components mounted on at least two electrically insulating columns (bead glass). A conductive region is formed on at least the back surface of each bead glass facing the neck. This conductive region has a function of preventing or suppressing discharge in the neck portion of a cathode ray tube having an electron gun assembly assembled from bead glass, and is called an arc suppressor. This conductive region has the effect of neutralizing the electric field along the axial direction and reducing the axial current to at least the point where discharge can be substantially prevented.

As a specific method for forming the conductive region, a surface treatment for bead glass and a coating treatment for bead glass can be mentioned. For example, a metal coating such as metal chromium, metal aluminum, metal silver, an Inconel alloy, or metal platinum is applied. Chromium, aluminum, silver and Inconel can be deposited from their vapors in a vacuum. This region can also be formed by a metallizing treatment such as applying or spraying an organic platinum compound layer on the bead glass and then heating the bead glass to cure the coating. This conductive region can be used before or after assembling the electron gun assembly.
Alternatively, it can be formed before or after sealing the electron gun assembly to the cathode ray tube neck, or before or after exhausting and sealing off the envelope. In one example, the electron gun assembly is sealed in the neck of a cathode ray tube, and after evacuating the inside of the tube, a conductive region is formed on the bead glass. For example, a heat-resistant metal ribbon (wire) is attached so as to surround the electron gun structure around the grid electrode G3. When high frequency energy is applied to the ribbon and heated after the cathode ray tube is evacuated, the metal evaporates and is deposited as a conductive region on the bead glass surface at a relatively low temperature. This method is called a wire suppressor method. To deposit chromium or silver by this method, a chrome-plated tungsten ribbon or a silver-plated stainless steel ribbon may be used. Alternatively, the conductive regions are formed before the bead glass is incorporated into the electron gun assembly. Specifically, a required portion of the bead glass is coated with an organoplatinum compound.
The coating of the organoplatinum compound can be formed by any known means such as coating, printing, spraying or transfer. Next, the bead glass coated with the organoplatinum compound is dried in air for about 50 hours.
The organic material is volatilized by heating to 0 ° C., and the film is hardened and then cooled to room temperature. The glass bead metallized by such a platinum coating method can be used for assembling an electron gun structure as it is.

However, in the wire suppressor method, there is a possibility that the ribbon or the wire itself triggers (strays) the discharge in the tube. Further, there is a possibility that the inside of the tube may be contaminated by the deposition of the wire. Furthermore, the process of performing high-frequency heating and vapor deposition of the wire (wire flash) requires a high degree of stability, and various restrictions occur in the actual work site. For example, it is necessary to accurately determine the position where the wire is to be attached. On the other hand, in the platinum coating method, the electric resistance of the conductive region tends to be too low. For this reason, electric field concentration occurs at the edge of the applied platinum pattern, which may cause damage due to discharge. In particular, for example, 6
When a voltage of 0 kV is applied, electric discharge occurs due to electric field concentration and damage is likely to occur. If damages such as dielectric breakdown occur, there is a possibility that the discharge triggers (strays) during the subsequent rated operation.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems of the prior art, the following measures have been taken. That is, the method for forming an arc suppressor according to the present invention basically includes assembling an electron gun mounted on a neck portion of a cathode ray tube, a plurality of electrode components arranged in an axial direction using a pair of support members made of bead glass. When holding and fixing, a conductive region is provided in advance in the bead glass to suppress discharge in the tube.
As a feature, this conductive region is formed by the following steps. First, a conductive paste is applied with a predetermined pattern to the back surface of the bead glass facing the neck portion and, if necessary, a part of the side surface continuous with the bead glass, and the conductive paste is applied along the axial direction from the inside of the pattern to the peripheral portion. It is improved so that the coating amount per unit area of the paste is reduced. Next, the conductive paste is baked at a predetermined temperature and diffused into the bead glass in accordance with the coating amount, thereby providing a conductive region whose resistance gradually increases from the inside to the periphery along the axial direction.

Preferably, the coating step includes simultaneously printing a conductive paste on the back and side surfaces of the bead glass using, for example, an intaglio transfer method, and changing the thickness of the printed conductive paste by changing the intaglio. Improve to decrease from the inside to the periphery. Also preferably, the coating step includes a conductive particles composed of ruthenium oxide or Sn-Sb oxides, the bead glass and homogeneous e.g. SiO ₂ -
And B ₂ O ₃ -K ₂ O-based glass frit, and an organic resin for binder, kneaded with conductive paste and a solvent for coating.
In some cases, the firing step includes firing the applied conductive paste simultaneously with firing the powder-molded bead glass.

According to the present invention, an arc suppressor is provided by forming a conductive region with a predetermined pattern on a part of the surface of the bead glass constituting the electron gun assembly. The resistance of the edge of the pattern is increased to obtain an arc suppressor structure free from secondary harm. Specifically, a conductive paste is applied to the back surface facing the neck portion of the bead glass and a part of the side surface as necessary. At this time, the thickness of the conductive paste is adjusted so as to become thinner from the inside toward the periphery along the axial direction. By subsequent firing, the electrical resistance in the axial direction at the interface between the bead glass and the conductive paste is improved so as to gradually increase from the inside toward the peripheral portion (edge portion). As a result, the concentration of the electric field at the edge portion is reduced, and damage to the conductive region due to discharge during conditioning is greatly reduced. For this reason, there is no stray caused by damage such as insulation breakdown due to conditioning which has conventionally been a problem during rated operation.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view showing a method for forming an arc suppressor according to the present invention. As shown in (A), in order to assemble the electron gun mounted on the neck portion 4 of the cathode ray tube, a plurality of support members made of bead glasses 11 and 12 are arranged in the axial direction (indicated by a dashed line). Are held and fixed. In the illustrated example, the electrode components are composed of grid electrodes G1 to G4. At this time, a conductive region 15 is provided in each of the bead glasses 11 and 12 in advance to suppress discharge in the tube. As a characteristic feature, for example, when focusing on one bead glass 11, a conductive paste is applied with a desired pattern on the back surface 11b facing the neck portion 4 and a part of the side surface 11s connected thereto, and the pattern is formed along the axial direction. From the inside to the periphery, the amount of coating of the conductive paste per unit area is improved so as to be reduced. Thereafter, the conductive paste is baked at a predetermined temperature and diffused into the bead glass 11 according to the amount of coating, and a conductive region 15 whose resistance value gradually increases from the inside to the periphery along the axial direction is provided. By this firing, the interface between the conductive paste and the beet glass is brought into a molten state, and the above-described diffusion occurs.

FIG. 2B is a partial cross-sectional view along the line XX shown in FIG. In the present embodiment, the conductive paste 15P is simultaneously printed on the back surface 11b and the side surface 11s of the bead glass 11 using the intaglio transfer method. At this time, the thickness of the conductive paste 15P printed by changing the intaglio is improved so as to decrease from the inside of the pattern to the periphery along the axial direction. This conductive paste is made of, for example, conductive particles made of ruthenium oxide or Sn—Sb oxide, SiO ₂ —B ₂ O ₃ —K ₂ O-based glass frit of the same quality as bead glass, an organic resin for a binder, and a solvent. It is a kneaded composition. Note that the conductive particles are not limited to those described above, and those that do not lose conductivity in a subsequent beading step may be used. Further, the above-mentioned glass frit is mixed in order to obtain adhesion with the bead glass, and for example, the same glass frit as the raw material of the multi-form glass is used. Incidentally, SiO ₂ -B ₂ O
The softening point of the _3- K ₂ O glass frit is 820 ° C., and the linear expansion coefficient is 27 × 1 in the temperature range of 25 to 300 ° C.
It is 0 ^-7 . The other B ₂ O ₃ -ZnO system and ZnO-B ₂
There is an O ₃ —SiO ₂ system.

FIG. 3C is a graph showing the resistance distribution along the axial direction at the interface between the bead glass 11 and the conductive paste 15P. The horizontal axis indicates the axial distance, and the vertical axis indicates the bead glass surface resistance. As is clear from the graph, the conductive region 15 has a resistance distribution in which the resistance value gradually increases from the inside to the periphery in the axial direction. That is, the central portion of the conductive region 15 has a resistance value of, for example, about 1 × 10 ⁹ Ω / □. On the other hand, the surface of the bead glass has a resistance value of, for example, about 10 ¹⁷ Ω / □. Conductive region 15
Has a predetermined width W and a resistance value of 1 × 1 from the inside to the periphery.
It gradually increases from ⁰⁹ Ω / □ to 1 × 10 ¹⁷ Ω / □. In this manner, the electric field concentration is eliminated by providing the edge portion of the conductive region 15 with a slope of the resistance value, and damage such as dielectric breakdown due to discharge during conditioning is suppressed. The slope of the resistance value can be formed, for example, by printing the conductive paste 15P such that the coating amount per unit area decreases from the inside of the pattern to the peripheral portion. That is, when the conductive paste 15P is baked at a predetermined temperature, the conductive particles contained in the conductive paste are diffused in accordance with the amount of coating, so that the concentration distribution has a gradient, which also leads to the slope of the resistance value.

FIG. 2 shows a cross-sectional shape of an intaglio used for applying a conductive paste by the intaglio transfer method. Here, among the intaglio printing methods, particularly, octopus printing is used, and the conductive paste can be simultaneously printed on the back and side surfaces of the bead glass. In the example shown in (A),
The printing pattern has a stepped shape with a large depth at the center and a small depth at the periphery. The thickness of the intaglio-printed conductive paste varies depending on the step shape. In the example shown in (B), the depth of the intaglio pattern continuously decreases from the inside toward the periphery. Accordingly, the thickness of the central portion of the intaglio-printed conductive paste increases, while the thickness of the peripheral portion decreases. In the example shown in (C), the print patterns are discretely formed. The coating amount per unit area of the conductive paste is small at the edge of the pattern.
By printing using such a pattern, the edge portion can be blurred and a desired resistance distribution can be provided. (D) shows the planar shape of the print pattern shown in (C). Note that, instead of the intaglio transfer method, another method such as a screen printing method can be used.

FIG. 3 is a graph showing the voltage dependence of the resistance value of the conductive region. The vertical axis shows the resistance value and the horizontal axis shows the applied voltage. In addition, the firing temperature of the conductive paste is 800
Samples were prepared in three stages of ℃, 850 ℃ and 900 ℃ to measure the resistance value of the conductive region. As is clear from the graph, when baked at 800 ° C., the resistance value of the conductive region is about 1 × 10 ⁸ Ω / □. When fired at 850 ° C., the resistance value is on the order of 1 × 10 ⁹ Ω / □. When fired at 900 ° C., the resistance further increases and approaches 1 × 10 ¹⁰ Ω / □. 8
At a sintering temperature of about 00 ° C., the conductive particles dispersed in the conductive paste are aggregated to some extent, and the fluidity of the glass is slightly insufficient. On the other hand, when baked at 900 ° C., the glass flows sufficiently and the conductive particles are also dispersed, so that the resistance value is increased.

FIG. 4 is a flowchart showing an assembly process of the electron gun assembly. First, in step S1, fired bead glass is prepared in advance. In step S2, a conductive paste is prepared. Proceeding to step S3, a conductive paste is printed on a predetermined portion of the bead glass by an intaglio transfer method or the like. Next, a drying process is performed in step S4 to evaporate the solvent contained in the conductive paste. Next, step S5
To perform a baking treatment. For example, heating is performed at 850 ° C. for about 10 minutes in an air atmosphere. By this heat treatment, the conductive particles contained in the conductive paste diffuse into the base bead glass. At this time, by changing the thickness of the conductive paste,
It becomes possible to give a desired gradient to the diffusion concentration. Thereafter, in step S6, a plurality of electrode parts necessary for the electron gun are prepared. In step S7, beading is performed, and a plurality of electrode components are held and fixed by a pair of bead glasses. Specifically, the electrode component is set on a positioning jig, and the bead glass is heated to, for example, about 1200 ° C. by a burner to soften the bead glass. In this softened state, the bead glass is pressed against the end of the electrode component to assemble the electron gun assembly. Since the back surface on which the conductive paste is printed is the back side of the surface directly heated by the burner, and the back surface is supported by metal,
The heating temperature does not reach 850 ° C. during firing, and the heating time is shorter than 1 minute. For this reason, the diffusion is small, and there is no risk of damage due to insufficient heat resistance. Thereafter, in step S8, a stem and a lead wire are prepared.
At 9, the connecting wire is assembled.

FIG. 5 is a flowchart showing a modified example of the arc suppressor forming method according to the present invention. In this modification, a conductive paste is printed at the stage of powder molding of the bead glass, and thereafter, the bead glass and the conductive paste are simultaneously fired. First, a glass frit is prepared in step S11, and a binder is prepared in step S12. In step S13, a frit and a binder are mixed and powder molding is performed to prepare a bead glass preform. In step S14, a conductive paste is separately prepared.
In step S15, a conductive paste is printed on the surface of the bead glass formed by powder molding. In step S16, a drying process is performed to volatilize the solvent contained in the conductive paste. In step S17, the bead glass and the conductive paste are fired simultaneously. Thus, the bead glass on which the arc suppressor is formed is completed.

[0017]

As described above, according to the present invention,
Conductive paste is applied with a predetermined pattern on the back surface of the bead glass facing the neck and a part of the side surface continuous with the bead as necessary, and the unit area of the conductive paste is applied from the inside of the pattern to the periphery along the axial direction. It is improved so that the amount of coating per hit is reduced. Thereafter, the conductive paste is baked at a predetermined temperature and diffused into the bead glass according to the amount of coating, and a conductive region is provided in which the resistance gradually increases from the inside to the periphery along the axial direction. By forming an arc suppressor with a resistance distribution in this way, it is possible to suppress discharge due to bead glass charging and secondary electron emission, and to significantly reduce damage to the conductive area due to discharge during conditioning. And no stray due to damage during rated operation. In addition, the conductive paste is inexpensive,
Since a strong film is formed by the baking treatment, there is no spalling and deterioration during assembling of the electron gun.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a method for forming an arc suppressor according to the present invention.

FIG. 2 is a schematic view showing an example of a pattern of an intaglio used in the arc suppressor forming method according to the present invention.

FIG. 3 is a graph showing the resistance of an arc suppressor formed according to the present invention.

FIG. 4 is a flowchart showing an assembling process of the electron gun assembly.

FIG. 5 is a flowchart showing another embodiment of the arc suppressor forming method according to the present invention.

FIG. 6 is a sectional view showing a general configuration of a cathode ray tube.

FIG. 7 is a sectional view showing a general configuration of an electron gun assembly.

[Explanation of symbols]

4 ... Neck, 6 ... Electron gun, 11 ... Bead glass, 11s ... Side, 11b ... Back, 12 ...
..Bead glass, 15 ... conductive area, 15P ...
Conductive paste

Claims (4)

[Claims] In order to assemble an electron gun mounted on a neck portion of a cathode ray tube, when a plurality of electrode components arranged in an axial direction are held and fixed using a pair of support members made of bead glass, the bead glass is preliminarily attached to the bead glass. A method for forming an arc suppressor that suppresses discharge in a tube by providing a conductive region, comprising applying a predetermined pattern to a back surface of a bead glass facing a neck portion and, if necessary, a portion of a side surface continuous with the bead glass. A coating process in which the coating amount per unit area of the conductive paste is reduced from the inside of the pattern to the peripheral portion along the axial direction, and the conductive paste is baked at a predetermined temperature and coated on bead glass. A baking step of providing a conductive region having a resistance gradually increasing from the inside to the peripheral portion along the axial direction by diffusing according to the amount of work. 2. The coating step includes simultaneously printing a conductive paste on the back surface, the back surface, and the side surface of the bead glass, and changing the thickness of the printed conductive paste by changing the printing plate from the inside of the pattern to the peripheral portion. The method for forming an arc suppressor according to claim 1, wherein the amount of the arc suppressor decreases. 3. The method according to claim 1, wherein the coating step includes ruthenium oxide or S
2. The arc suppressor according to claim 1, wherein a conductive paste obtained by kneading conductive particles made of n-Sb oxide, glass frit of the same quality as bead glass, an organic resin for a binder, and a solvent is applied. Forming method. 4. The arc suppressor forming method according to claim 1, wherein in the firing step, the applied conductive paste is fired simultaneously with the firing of the powder molded bead glass.