JP2956177B2 - Glass front panel - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube for an electronic display for forming an image, and particularly to a glass front panel used for a cathode ray tube suitable for a thin image display device. .

[Prior Art] A thin image display device is disclosed in the Journal of the Institute of Television Engineers of Japan, Vol.
Japanese Patent Application Laid-Open No. 62-153148 discloses an image display apparatus using a matrix drive method as disclosed in Japanese Patent Application Laid-Open No. 62-153148. The front panel has an image display portion having a flat surface, a side wall portion connected to the image display portion, and a flange portion bent from the side wall portion and connected to the image display portion. The glass front panel is used as a sealed vacuum vessel which is joined to a rear panel, for example, by a metal plate and a glass frit.

In this image display apparatus, an electron beam is emitted from an electron gun unit composed of a group of electron beam control electrodes arranged in a matrix, and this electron beam is applied to a phosphor provided on an inner surface of an image display section of a glass front panel. Thus, image display is realized. In order to realize such an image display, a power supply voltage is supplied to the electron gun unit. As this power supply path, an external lead-out terminal is provided so as to penetrate a joint portion made of, for example, a glass frit for joining a glass front panel and a rear panel, and power is supplied from the external lead-out terminal to the electron gun unit. It is configured.

[Problem to be Solved by the Invention] However, when displaying an image, there is a few gaps between the image display section of the front panel and the electrode terminal that is attached through the glass frit at the joint between the front panel and the rear panel. Since a high voltage of kv or more is applied, there is a problem that electric charges charged to the front panel are instantaneously discharged through the adhesive layer of the glass frit and cracks are generated on the adhesive layer and the surface of the front panel.

The present invention does not cause damage due to dielectric breakdown on the inner surface of the glass frit or the front panel as described above during image display, does not cause coloring deterioration even when irradiated with an electron beam, and has a low mechanical strength. An object of the present invention is to provide a large glass front panel used for a cathode ray tube for an image display device and a method of manufacturing the same.

Means for Solving the Problems The present invention provides an electron gun unit that emits an electron beam under reduced pressure according to an input video signal, a fluorescent unit that emits light by an electron beam from the electron gun unit, and the fluorescent unit. Has an image display portion provided on the inner surface and a side wall portion connected to the image display portion and a flange portion connected to the side wall portion, than the inside formed by ion exchange treatment in a molten salt containing potassium ions. A glass front panel having an electron beam coloring surface layer containing many potassium ions, a rear panel joined to the glass front panel and accommodating the electron gun unit together with the glass front panel, and the electron gun A glass front panel used for a cathode ray tube having an external lead-out terminal electrically connected to a unit, A front panel made of glass, wherein the surface layer of the flange portion is substantially removed.

The surface layer having an electron beam coloring resistance according to the present invention may be, for example, a glass front panel made of a molten salt containing potassium nitrate as a main component disclosed in JP-A-62-153148 or JP-A-1-203244. Immersion, and ion exchange between sodium ions near the surface of the glass and potassium ions in the molten salt, the ratio of alkali ions in the surface layer to K ₂ O /
(K ₂ O + Na ₂ O) The molar ratio represented by 0.2 or more, preferably 0.3
~ 0.6.

By the above method, at least the image display portion of the glass front panel had a surface layer containing more potassium ions than the inside of the glass to a depth of about 15 μm from the surface, and the coloring property was reduced with respect to electron beam irradiation. Can be surface layer. At the same time, compressive strain is formed in the surface layer, so that the mechanical strength of the glass front panel can be increased. In the flange portion of the glass front panel of the present invention, the above-mentioned surface layer containing more potassium ions than the inside does not substantially exist. The above-mentioned surface layer may be present in all parts other than the flange part, or may be present only in the image display part to which the electron beam is irradiated when displaying an image.

When the surface layer containing a large amount of potassium ions exists near the surface of the flange portion, the electric resistivity near the glass surface becomes larger than the electric resistivity inside the glass, and the surface layer is charged with electric charge during image display. As a result, dielectric breakdown occurs when electric charges charged on the surface layer are discharged. Such dielectric breakdown is more likely to occur if there are localized defects such as foreign matter and protrusions on the surface of the flange portion and the glass frit. Therefore, it is preferable to lower the resistance of the surface layer so that the electrical resistivity becomes substantially the same as the inside of the glass. When an image is displayed, the temperature of the glass front panel becomes high, so that the electrical insulation of the glass front panel is further reduced. Therefore, the dielectric breakdown caused by the discharge is more likely to occur in a high-brightness cathode ray tube.

In addition, the surface where the flange portion of the front panel is joined to the rear panel and the end surface of the flange portion (indicated by 1d in FIG. 1 (c)) are discharged from the tip if the surface has minute projections, and dielectric breakdown occurs. Therefore, it is preferable to make the surface unevenness a smooth surface of 3 μm or less in order to suppress dielectric breakdown during image display.

As the glass of the glass front panel of the present invention,
The use of glass having an electric resistivity at 150 ° C. of 10 ¹⁰ Ωcm or less can greatly reduce damage due to dielectric breakdown. Examples of such a glass include a glass having a soda lime silica composition manufactured by a float method and a known cathode ray tube glass containing BaO or an alkaline earth metal oxide, and in particular, a glass having a soda lime silica composition manufactured by a float method. Glass is most preferable from the viewpoint of economy because it can be obtained at low cost.

The glass front panel of the present invention can use a known press molding method using a mold having a predetermined shape by heating a glass plate or a molding method of directly molding from a glass gob.

According to a second aspect of the present invention, an electron gun unit that emits an electron beam under reduced pressure according to an input video signal, a fluorescent unit that emits light by an electron beam from the electron gun unit, and the fluorescent unit are provided on an inner surface. It has an image display portion, a side wall portion connected to the image display portion, and a flange portion connected to the side wall portion, and contains more potassium ions than inside formed by ion exchange treatment in a molten salt containing potassium ions. A glass front panel having an electron beam resistant surface layer, a rear panel joined to the glass front panel and accommodating the electron gun unit together with the glass front panel, and electrically connected to the electron gun unit. In the glass front panel used for a cathode ray tube having an external lead-out terminal, the outer circumference and the inner circumference of the side wall are reduced. And to one side, the electrode having a field relaxation resistance is a glass front panel provided on the strip.

As a material constituting the electric field relaxing electrode according to the present invention, a semiconductor material or a mixture of a semiconductor material and a conductor material can be used. As the semiconductor material, silicon carbide, tungsten carbide, a mixture of zinc oxide and bismuth oxide, and fine powder such as cuprous oxide can be used. As the conductive material, fine powder such as carbon, silver, and copper can be used. . By mixing these semiconductor materials or a semiconductor material and a conductor material, the electrical resistivity in a dry state is 10 ⁵ to 1
Preferably used is adjusted to the range of 0 ⁹ [Omega] cm. The strip-shaped electrode having the above electrical resistivity is applied to the outer peripheral surface and / or the inner peripheral surface of the side wall portion of the glass front panel of the cathode ray tube, and then dried and provided. If the electrical resistivity is less than 10 ⁵ Ωcm, it is radiated from the electron gun unit, passes through the space inside the glass container near the glass front panel and the side wall, and collides with the phosphor corresponding to the periphery of the image display unit The generated electrons are deflected under the influence of the space potential generated near the side wall, and the image is disturbed at the periphery of the image, which is not preferable. On the other hand, when the electrical resistivity is 10 ⁹ Ωcm or more, the relaxation of the electric field intensity becomes insufficient, which is not preferable.

Therefore, the resistivity of the strip-shaped electrode provided on the side wall is 10
By setting the electric resistivity to ⁵ to 10 ⁹ Ωcm, it is possible to obtain a cathode ray tube in which the image is not disturbed and the glass is prevented from being broken by local high-pressure discharge.

In addition, in order to quickly discharge and remove electrons charged on the side wall of the front panel, a conductive material is formed on the side close to the rear panel in contact with the strip-shaped electrode having an electric resistivity of 10 ⁵ to 10 ⁹ Ωcm. Two band-shaped electrodes may be provided.
At this time, the second strip-shaped electrode and the 10 ^5-1 made of a conductor
0 ⁹ [Omega] cm boundary between electrode having an electrical resistivity of, be prevented out fluorescent side than near surface most to the image display unit of the electron gun unit, preferable for does not cause image distortion. In order to provide an electric field relaxing electrode on the side wall of the front panel, 30 to 80% by weight of the above fine powder is added to a varnish such as an epoxy resin acrylic resin or an adhesive binder such as alumina sol or potassium silicate solution.
It is obtained by dispersing to a certain extent, applying and drying this liquid.

The electrical resistivity of the electrode made of a conductor on the side wall is 10%.
A conductive paint of ² to 10 ^-4 Ωcm can be used, and a paint obtained by mixing fine silver powder with an organic or inorganic binder can be used.

A third aspect of the present invention is a glass front having an image display portion having a predetermined shape by heating a glass plate, a side wall portion bent and connected from the image display portion, and a flange portion bent and connected from the side wall portion. After forming the panel, the entire glass front panel thus formed contains more potassium ions than the inside of the glass by ion exchange between potassium ions in the molten salt and sodium ions near the surface of the glass front panel. Forming a surface layer having electron beam resistance, and then immersing only the flange portion in an etching solution containing hydrofluoric acid, or immersing it in an alkali eluate containing an inorganic acid, only the surface layer of the flange portion is formed. This is a method for producing a glass front panel having electron beam coloring resistance, in which the glass is substantially removed.

In the method of the present invention, the provision of a surface layer containing more potassium ions than the inside of the entire glass front panel is disclosed in, for example, JP-A-62-153148 and JP-A-Hei.
The method disclosed in -203244 can be used. The surface layer formed on the glass front panel has Na ₂ O and K ₂ O in a molar ratio represented by K ₂ O / (Na ₂ O + K ₂ O) of 0.2 or more, preferably 0.3 to 0.6. You.

After forming the electron beam-resistant surface layer on the entire glass front panel, the etching solution for dissolving and removing the electron beam-resistant surface layer of the flange portion with an acid containing hydrofluoric acid is a hydrofluoric acid. A solution obtained by diluting an acid with water can be used. As the concentration of hydrofluoric acid, an aqueous solution of 1 to 20% is usually used, and a 3 to 10% aqueous solution or a solution obtained by adding 5 to 20% sulfuric acid to this aqueous solution has a high speed of dissolving and removing and removes it. It is preferable for ensuring reproducibility and smoothness of the thickness of the surface to be formed. In addition, an aqueous solution containing an acid such as nitric acid or hydrochloric acid can be used depending on the composition of the glass. The aqueous solution containing hydrofluoric acid removes most of the electron beam-resistant surface layer having a large electric resistivity as described above, thereby eliminating micro scratches and micro projections on the surface caused by the ion exchange treatment. The electrical resistivity of the glass surface can be made substantially the same as that of the inside by making the surface state in which abnormal discharge with a rounded shape is less likely to occur. In addition, it is preferable that the smoothness of the surface of the flange portion of the front panel to be joined to the rear panel and the surface of the end surface does not exceed 3 μm from the viewpoint of suppressing the dielectric breakdown due to the discharge during image display.

Further, a layer which selectively elutes alkali ions in the surface layer, that is, changes the electron beam resistant surface layer having a large electric resistivity to the same degree as the inside, and has a substantially large electric resistivity A solution containing an inorganic acid can be used as an eluate used for removing the carboxylic acid. Particularly, a solution containing sulfuric acid as a main component is preferable because the surface of the flange portion after elution is smoothed and elution is performed in a short time and with good reproducibility, and the concentration of sulfuric acid is preferably 30% or more. Further, an acid such as hydrochloric acid or nitric acid may be added to sulfuric acid.
Further, the etching solution or the eluate can be used after being heated.

When the surface layer of the flange portion is removed by mechanical polishing and subsequent etching or elution as described above, the surface roughness is preferably reduced to R _MAX 8 μm or less in advance by mechanical polishing.

[Operation] The surface layer of the glass front panel of the present invention, which contains potassium ions more than the inside and has electron beam resistance and a large electric resistivity, is formed in the image display portion, and substantially has a flange portion. Is not formed. Therefore, at the time of image display, blackening due to electron beam irradiation of the image display portion is suppressed, and at the same time, the electrical resistivity of the surface of the flange portion is substantially the same as that inside the glass. And the occurrence of microcracks on the bonding layer and the glass surface of the flange portion is suppressed.

Further, in the method of the present invention, dissolving and removing the surface layer of the flange portion with an aqueous solution of hydrofluoric acid and eluting alkali ions which cause an increase in the electrical resistivity of the surface layer can be performed by displaying an image of the flange portion surface. At the same time, the surface is made smooth without fine projections that cause dielectric breakdown, and at the same time, the difference in electrical resistivity between the surface and the inside of the flange is reduced, and the amount of charge on the surface of the flange is reduced.

Further, the strip-shaped electrodes provided on the side wall of the glass front panel according to the present invention are charged by applying a high voltage without causing distortion in the image when the image is displayed by controlling the electric resistivity. The electric charge on the front panel surface is prevented from being abnormally discharged on the front panel surface or flange portion with a large current momentarily.

[Examples] Hereinafter, the present invention will be described based on examples. FIG. 1 (a) is an external view of one embodiment of a glass front panel of the present invention, and FIG. 1 (b) is a cross-sectional view of the glass front panel of FIG. 1 along AA. In FIG. 1, a glass front panel 1 has a flat image display section 1a and a side wall section 1b which is bent from the image display section 1a and has a resistance to electron beam coloring containing more potassium ions than the inside indicated by a dotted line. And a surface layer having a compressive strain for improving the mechanical strength of the glass front panel is provided, and the surface layer is not provided on the flange portion 1c.
The flange portion according to the present invention is indicated by a hatched portion in FIG. 1 (C).

FIG. 2 is a sectional view of another embodiment of the glass front panel of the present invention. A band-shaped electric field relaxing electrode 2 is provided on the outer side of the side wall portion 1b near the image display portion 1a, and a band-shaped conductor 3 is provided on the side near the flange portion 1c.
Are partially overlapped with each other.

FIG. 3 is a schematic sectional view of a cathode ray tube using the glass front panel of the present invention. In FIG. 3 (a),
The inside of the glass front panel 1 is coated with a phosphor 5, further coated with an aluminum thin film 6, and an anode terminal 4 is drawn out of the aluminum thin film 6 to the outside. The rear panel 10 is a panel made of a flat metal covering the rear opening of the front panel 1, and includes a glass front panel 1 and a real panel.
10 is bonded by a glass frit 9 and the space 11 is maintained at a reduced pressure. An external lead-out terminal 8 is inserted into the space 11 from the outside through the glass frit 9 and connected to the electron gun unit 7. Thus, the cathode ray tube 12 is configured.

FIG. 3 (b) shows a band-shaped electric field relaxing electrode 2 on the side of the outer periphery of the side wall of the glass front panel near the image display unit.
Further, a strip-shaped electrode 3 made of a conductor is provided on the side near the rear panel 10 so as to partially overlap the electric field relaxing electrode 2.

FIG. 3 (c) shows a cathode ray tube in which an electric field relaxing electrode 2 is provided inside the side wall of the glass front panel 1.

The glass of the glass front panel 1 is subjected to an ion exchange treatment using a molten salt containing potassium ions,
It is preferable that the surface layer is formed so that the coloring is suppressed by electron beam irradiation and the mechanical strength of the glass is improved by the generated compressive strain.

The operation of the cathode ray tube configured as described above will be briefly described. The electron gun unit 7 operates based on the power supply and the television signal supplied through the external extraction terminal 8, and an electron beam corresponding to the television signal emitted from the electron gun unit 7 is transmitted through the anode terminal 4 through the aluminum terminal 4. The film is accelerated by the high voltage applied to the thin film 6 and collides with the phosphor 5 disposed on the image display unit of the glass front panel 1 to emit light, thereby forming an image. As such an image display operation is performed, the glass front panel is charged. In the case of a device using a conventional front panel, dielectric breakdown occurred in a flange portion and a side wall portion of the front panel due to the charged charges. In this embodiment, since the electric charge is uniformly discharged by the electrode provided on the side wall portion, there is no instantaneous discharge. Therefore, the side wall portion is protected, and the flange portion has high dielectric breakdown strength. An abnormal discharge occurs between the portion and the external lead-out terminal 8, and damages such as generation of fine scratches on the surface of the flange portion can be prevented.

FIG. 4 is a partial cross-sectional view of a cathode ray tube for explaining the action of the electric field relaxing (reducing the electric field strength on the material surface) electrode according to the present invention in more detail. When the electric field relaxation electrode is not provided on the side wall of the glass front panel 1, electrons accelerated from the electron gun 7 are irradiated on the aluminum thin film 6 of the image display unit, so that the surface of the glass front panel on the side wall is formed. The electric potential distribution changes rapidly at the boundary between the strip-shaped conductive electrodes 3 as shown in FIG. 4B, but when the electric field relaxing electrode 2 is provided, FIG. As shown in (2), since the potential distribution on the surface of the glass panel on the side wall portion gradually changes, occurrence of creeping discharge is prevented.

FIG. 5 shows an embodiment of the method of the present invention, in which a glass front panel 1 is provided with a processing solution 15 for etching or elution contained in a container 14 having a heater 13.
Only the flange portion is soaked, and the surface layer of the flange portion is selectively removed.

Example 1 Glass A of Table 1 having a thickness of 5 mm formed by the float method
Was cut into a predetermined shape. The cut surface of this glass was polished using a # 400 roughness diamond wheel to reduce the surface roughness to R _MAX 7.
It was 5 μm. By heating this glass plate and using a known press molding method, the depth is 40 mm, the diagonal length of the image display unit is 25 cm,
A glass front panel having a flange surface having a joining surface width of 15 mm was formed. Thereafter, the front panel was immersed in a molten salt of potassium nitrate heated to 460 ° C. for 3 hours, taken out, and washed and dried.

Thereafter, the flange portion of the glass front panel having increased electron beam coloration resistance and increased mechanical strength is immersed in a 5% hydrofluoric acid aqueous solution as shown in FIG. 5, and about 5 μm from the surface of the glass. Dissolve and remove The surface layer containing a large amount of potassium ions was substantially removed.

The obtained glass front panel was joined to a metal rear panel using a glass frit (trade name “IFW-029B” manufactured by Iwaki Glass Co., Ltd.) to produce a cathode ray tube as shown in FIG. 3 (a). Put this cathode ray tube in 150
The sample was placed in an atmosphere of ° C., and a voltage of 10 kv was continuously applied to the image display unit for 300 hours, but no crack was generated on the glass front panel or the glass frit.

Example 2 Glass A of Table 1 having a thickness of 5 mm formed by the float method
Was cut into a predetermined shape. The cut surface of this glass was polished using a # 400 roughness diamond wheel to reduce the surface roughness to R _MAX 7.
It was 5 μm. By heating this glass plate and using a known press molding method, the depth is 40 mm, the diagonal length of the image display unit is 25 cm,
A glass front panel having a flange surface having a joining surface width of 15 mm was formed. The front panel was immersed in a molten salt of potassium nitrate heated to 460 ° C. for 3 hours, taken out and washed with water and dried.

After that, the flange part of this glass front panel, which has improved electron beam coloration resistance and mechanical strength,
Immersed in a sulfuric acid aqueous solution as shown in Fig. 5 and about 4.
Sodium ions and potassium ions existing up to a depth of 5 μm were eluted, and the surface layer containing a large amount of alkali ions was substantially removed.

The obtained glass front panel was joined to a metal rear panel by a glass frit (trade name “IWF-029B” manufactured by Iwaki Glass Co., Ltd.) to produce a cathode ray tube as shown in FIG. 3 (a). The cathode ray tube was placed in an atmosphere of 120 ° C., and a voltage of 10 kv was continuously applied to the image display unit for 500 hours. No crack was generated on the glass front panel or the glass frit.

Example 3 Glass B of Table 1 having a thickness of 5 mm formed by the float method
Was cut into a predetermined shape. The cut surface of this glass plate was polished using a diamond wheel having a roughness of # 400 to have a surface roughness of R _MAX 7.5 μm. The glass plate was heated to form a glass front panel having a depth of 40 mm, a diagonal length of the image display portion of 25 cm, and a width of a joining surface of the flange portion of 15 mm by a known press molding method. The front panel was immersed in a molten salt of potassium nitrate heated to 460 ° C. for 7 hours, taken out and washed with water and dried.

After that, the flange portion of the glass front panel having the electron beam resistance and the increased mechanical strength is subjected to a fifth aqueous solution of a mixed acid of hydrofluoric acid and sulfuric acid adjusted to 5% for hydrofluoric acid and 10% for sulfuric acid. As shown in the drawing, about 8 μm was dissolved and removed from the surface, and the surface layer containing a large amount of potassium ions was substantially removed.

The obtained glass front panel was joined to a metal rear panel by a glass frit (trade name “IWF-029B” manufactured by Iwaki Glass Co., Ltd.) to produce a cathode ray tube as shown in FIG. 3 (a). The cathode ray tube was placed in an atmosphere of 150 ° C., and a voltage of 10 kv was continuously applied to the image display unit for 300 hours. No crack was generated on the glass front panel or the glass frit.

Example 4 A 5 mm-thick glass plate having a composition indicated by glass B in Table 1 was produced by a float method. Heat this glass plate,
By a known press molding method, a glass front panel having a depth of 40 mm, a diagonal length of the image display portion of 25 cm, and a width of a joining surface of the flange portion of 15 mm was manufactured. Thereafter, in the same manner as in Example 1, the glass front panel was immersed in a molten salt of potassium nitrate heated to 460 ° C. for 7 hours and taken out.
Further, the surface layer containing potassium ions in the flange portion was removed in the same manner as in Example 1.

The obtained glass front panel was joined to a metal rear panel with a glass frit (trade name “IWF-029B” manufactured by Iwaki Glass Co., Ltd.) to produce a cathode ray tube as shown in FIG. 3 (a). The cathode ray tube was placed in an atmosphere of 150 ° C., and a voltage of 10 kv was continuously applied to the image display unit for 300 hours. However, no dielectric breakdown phenomenon was observed, and no crack occurred on the front panel or the glass frit. .

Example 5 Glass A of Table 1 having a thickness of 5 mm formed by the float method
A glass plate having a soda lime silica composition represented by is heated by a known press molding method to form a glass front panel having a depth of 40 mm, a diagonal length of an image display unit of 25 cm, and a width of a joining surface of a flange unit of 15 mm. Formed. This front panel
It was immersed in a molten salt of potassium nitrate heated to 460 ° C. for 3 hours, taken out and washed with water and dried.

Thereafter, the flange portion of the glass front panel, which is resistant to electron beam coloring and has increased mechanical strength, is immersed in a 5% hydrofluoric acid aqueous solution as shown in FIG.
m was dissolved, and the surface layer containing much potassium ions was removed. The obtained glass front panel was joined to a metal rear panel by a glass frit (trade name “IWF-029B” manufactured by Iwaki Glass Co., Ltd.) to produce a cathode ray tube as shown in FIG. 3 (a). The cathode ray tube was placed in an atmosphere of 150 ° C., and a voltage of 10 kv was continuously applied to the image display unit for 300 hours. No crack was generated on the glass front panel or the glass frit.

Example 6 Glass A of Table 1 having a thickness of 5 mm formed by the float method
By heating a glass plate of soda lime silica composition shown in, the vacuum forming method with a press, the depth is 40 mm,
A front panel having a diagonal length of 25 cm and a width of the joining surface of the flange portion of 15 mm was formed. The front panel was immersed in a molten salt of potassium nitrate heated to 460 ° C. for 3 hours, taken out, washed and dried.

Then, the flange portion of the glass front panel, which is resistant to electron beam coloring and has increased mechanical strength, is immersed in a 5% aqueous hydrofluoric acid solution as shown in FIG. 6 to dissolve the glass surface by about 10 μm. The surface layer containing a large amount of potassium ions was removed.

A band-shaped electrode was coated on the side wall of the obtained glass front panel using a coating liquid containing 50% by weight of silicon carbide fine powder and 50% by weight of alumina sol. This electrode covered the entire periphery of the side wall in a band shape from a position about 35 mm from the rear panel to a position where the front surface 7a of the electron gun unit crossed the side wall. Further, the conductive electrode was provided in a band shape with a width of about 13 mm on the entire periphery of the side wall portion on the flange portion side so as to overlap the electric field relaxing electrode by about 3 mm. The electrode made of carbon was prepared by applying a mixture of fine carbon powder and alumina sol. Using this front panel, a cathode ray tube shown in FIG. 3 (b) was manufactured. Connect the carbon strip electrode to the external ground terminal to form an aluminum thin film on the image display
The electron beam accelerated at 10 KV is injected into a constant temperature
Irradiation was continued for 00 hours. No crack was generated in any of the side wall portion, the flange portion, and the bonded portion of the front panel due to abnormal discharge.

Example 7 As shown in FIG. 3 (c), a strip-shaped electrode made of a mixture of carbon fine powder and titanium oxide fine powder and having an electric resistivity of about 1 × 10 ⁹ Ωcm, as shown in FIG. 3 (c). A cathode ray tube was manufactured in the same manner as in Example 2, except that was added to the inner surface of the side wall. The continuous irradiation of the electron beam was performed for 10,000 hours in the same manner as in Example 2, but no crack was generated in any of the side wall, the flange, and the bonded portion of the front panel due to abnormal discharge.

Example 8 Glass A of Table 1 having a thickness of 5 mm formed by the float method
A glass plate having a soda-lime-silica composition represented by was heated, and a known press molding method was used to mold a glass front panel having a depth of 40 mm, a diagonal length of the image display portion of 25 cm, and a flange portion of 15 mm in width. . Thereafter, the front panel was immersed in molten salt of potassium nitrate heated to 460 ° C. for 2 hours to form a surface layer containing more potassium ions than inside. The front panel having the surface layer formed on the obtained flange portion was joined to a metal rear panel with a glass frit (trade name “IWF-029B” manufactured by Iwaki Glass Co., Ltd.), and as shown in FIG. The cathode ray tube as shown was manufactured.

A band-shaped electrode was coated on the side wall of the obtained glass front panel using a coating liquid containing 50% by weight of silicon carbide fine powder and 50% by weight of alumina sol. This electrode covered the entire periphery of the side wall in a band shape from a position about 35 mm from the rear panel to a position where the front surface 7a of the electron gun unit crossed the side wall. Further, the conductive electrode was provided in a band shape with a width of about 13 mm on the entire periphery of the side wall portion on the flange portion side so as to overlap the electric field relaxing electrode by about 3 mm. The electrode made of carbon was prepared by applying a mixture of fine carbon powder and alumina sol. Using this front panel, a cathode ray tube shown in FIG. 3 (b) was manufactured. Connect the carbon strip electrode to the external ground terminal to form an aluminum thin film on the image display
The electron beam accelerated at 10 KV is injected into a constant temperature
Irradiation was continued for 00 hours. No crack was generated in any of the side wall portion, the flange portion, and the bonded portion of the front panel due to abnormal discharge.

Comparative Example 1 Glass A of Table 1 having a thickness of 5 mm formed by the float method
A glass plate having a soda-lime-silica composition represented by was heated, and a known press molding method was used to mold a glass front panel having a depth of 40 mm, a diagonal length of the image display portion of 25 cm, and a flange portion of 15 mm in width. . Thereafter, this front panel was immersed in a molten salt of potassium nitrate heated to 460 ° C. for 2 hours to form a surface layer containing more potassium ions than inside. The front panel having the surface layer formed on the obtained flange portion was joined to a metal rear panel using a glass frit (trade name “IWF-029B” manufactured by Iwaki Glass Co., Ltd.), and as shown in FIG. The cathode ray tube as shown was manufactured. This cathode ray tube was placed in an atmosphere of 150 ° C., and a voltage of 10 KV was continuously applied to the image display unit for 100 hours.
Many abnormal discharge traces were found on the joint surface of the flange portion, and many fine cracks were generated on the glass frit. It was also found that lead oxide contained in the glass frit was reduced and became a starting point of electric field breakdown.

Comparative Example 2 A glass front panel was manufactured in the same manner as in Example 4 using a glass plate having a composition indicated by glass B in Table 1 and was made of glass having a surface layer containing potassium ions more than the inside on the entire glass surface. The front panel was manufactured. Using this front panel, a cathode ray tube shown in FIG. 3A was manufactured. The space between the cathode lines was placed in an atmosphere of 150 ° C., and a voltage of 10 KV was continuously applied to the image display unit for 100 hours.
Many abnormal discharge traces were found on the joint surface of the flange portion, and many fine cracks were generated on the glass frit. It was also found that lead oxide contained in the glass frit was reduced and became a starting point of electric field breakdown.

[Effects of the Invention] The cathode ray tube using the glass front panel of the present invention does not blacken the image display portion by electron beam coloring at the time of image display, does not lower the luminance, and has a charge charged on the front panel surface. , The damage due to the instantaneous discharge is suppressed, so that a stable image with large luminance can be obtained.

Further, according to the method for manufacturing a glass front panel of the present invention, a glass having a soda-lime-silica composition that can be mass-produced or a glass not containing a large amount of an expensive potassium raw material can be used as a base plate, so that it is economically efficient. It is possible to manufacture a glass front panel having electron beam resistance and suppressing abnormal discharge. Further, according to the method of the present invention, the surface layer of the flange portion for suppressing the occurrence of abnormal discharge can be selectively and easily removed, and a smooth surface can be obtained after the removal.

[Brief description of the drawings]

1 (a), 1 (b) and 1 (c) are an external view and a cross-sectional view, respectively, of one embodiment of a glass front panel of the present invention. FIG. 2 is a sectional view of another embodiment of the glass front panel of the present invention. FIG. 3 is a sectional view of an embodiment of a cathode ray tube using the glass front panel of the present invention. FIG. 4 is a diagram for explaining the operation of the electric field relaxing electrode according to the present invention, and FIG. 5 is a diagram for explaining a method for manufacturing a glass front panel of the present invention. 1 ... Glass front panel, 1a ... Image display unit, 1b
... side wall, 1c ... flange, 2 ... electric field relaxing electrode, 3 ... electrode made of electric conductor, 4 ... anode terminal, 5 ...
... Phosphor, 6 ... Aluminum thin film, 7 ... Electron gun unit,
8 external draw-out terminal, 9 glass frit, 10 rear panel, 11 space, 12 cathode ray tube, 15 processing solution

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-203244 (JP, A) JP-A-62-153148 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 29/86 H01J 31/12 C03C 21/00

Claims (7)

(57) [Claims] An electron gun unit for emitting an electron beam under reduced pressure in accordance with an input video signal, a fluorescent means for emitting light by an electron beam from the electron gun unit, and an image display provided with the fluorescent means on its inner surface Portion having a side wall portion connected to the image display portion and a flange portion connected to the side wall portion, and having an electron-resistance including more potassium ions than the inside formed by an ion exchange treatment in a molten salt containing potassium ions. A glass front panel having a line-colorable surface layer, a rear panel joined to the glass front panel and accommodating the electron gun unit with the glass front panel, and electrically connected to the electron gun unit. In a glass front panel used for a cathode ray tube having an external extraction terminal, the surface layer of the flange portion is substantially Glass front panel, characterized in that was removed. 2. The glass front panel according to claim 1, wherein the substantial removal of the surface layer of the flange portion is at least 4 μm removed from the surface by mechanical polishing and / or chemical etching. . 3. The method according to claim 1, wherein the substantial removal of the surface layer of the flange portion is a step of selectively eluting at least 4 μm of alkali ions from at least the glass surface in the surface layer. Glass front panel. 4. An electron gun unit for emitting an electron beam under reduced pressure in accordance with an input video signal, a fluorescent means for emitting light by an electron beam from said electron gun unit, and an image display provided with said fluorescent means on its inner surface. Portion having a side wall portion connected to the image display portion and a flange portion connected to the side wall portion, and having an electron-resistance including more potassium ions than the inside formed by an ion exchange treatment in a molten salt containing potassium ions. A glass front panel having a line-colorable surface layer, a rear panel joined to the glass front panel and accommodating the electron gun unit with the glass front panel, and electrically connected to the electron gun unit. In a glass front panel used for a cathode ray tube having an external lead-out terminal, an outer circumference and an inner circumference of the side wall are reduced. To one side, a glass front panel, characterized in that the electrode having the electric field relaxation is provided on the strip. 5. The electric field relaxing electrode has an electric resistivity of 10 ⁵ to 10 ⁹ Ωcm, and is in contact with the strip-shaped electric field relaxing electrode on a side near a flange portion on a surface of the side wall portion, 5. The glass front panel according to claim 4, wherein a second conductive electrode is provided. 6. The value of viscosity coefficient η at 150 ° C. is log η ≦ 11.
The glass front panel according to any one of claims 1 to 5, wherein a glass base material is used. 7. A glass front panel formed by heating a glass plate and having an image display portion having a predetermined shape, a side wall portion bent and connected from the image display portion, and a flange portion bent and connected from the side wall portion. Then, by ion exchange between potassium ions in the molten salt and sodium ions in the vicinity of the surface of the glass front panel, an electron beam containing more potassium ions than the inside of the glass is formed in the entire formed glass front panel. Forming a surface layer having coloring properties, and then immersing only the flange portion in an etching solution containing hydrofluoric acid, or immersing it in an alkali eluate containing an inorganic acid, substantially only the surface layer of the flange portion Of producing a glass front panel having electron beam coloring resistance which has been removed.