JPH03156830A - Bulb recovering method for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To recover a bulb with a high yield without breaking a panel and a funnel by dissolving the bulb outside face side of a frit glass so that the dissolved face becomes irregular. CONSTITUTION:A mesh with high chemical resistance or a member 21 with many slit-shaped openings is fitted by sticking or the like so as to surround the outer periphery of the connection section between a panel 1 integrally connected by a frit glass 2 and a bulb 4 made of a funnel 3 and having no exterior member, it is immersed in a dissolving liquid mainly made of nitric acid, and the frit glass 2 is dissolved from the outside face side of the bulb 4. The dissolution face 22 of the frit glass 2 is partially blocked by non-opening portions of the member 21 and becomes a dissolution face with many irregularities. Cracks are generated on the frit glass 2 by a heat shock, and the panel 1 and the funnel 3 are separated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a glass panel and a glass funnel that are joined together by frit glass.

(Prior Art) Generally, a color cathode ray tube has a glass funnel (3) integrally joined to the panel (1) by a glass panel (1) and a frit glass (2), as shown in FIG.
) and has a valve (4) consisting of blue, green,
A phosphor screen consisting of a three-color phosphor layer that emits red light (
5), a shadow mask (B) in which a large number of electron beam passage holes are formed, an electron gun (7) that emits three electron beams, and various other tube internal members are provided. The valve (4)
The proportion of the manufacturing cost of color cathode ray tubes is high (
Collecting and reusing bulbs that have become defective during manufacturing or from defective products is effective in reducing the manufacturing cost of color cathode ray tubes.

Normally, color cathode ray tubes are manufactured by forming a phosphor screen on the inner surface of a single panel that is not joined to a funnel, and then joining it to a funnel. Therefore, in order to collect and reuse the bulbs of color cathode ray tubes, it is necessary to separate the panels and funnels that are integrally joined.

Conventionally, in a color cathode ray tube bulb recovery method, for example, for a tube whose interior has already been evacuated, air is introduced into the tube by first making, for example, a through hole at the neck end of the funnel. Next, the bulb into which air has been introduced is immersed in an aqueous nitric acid solution containing about 15% by weight, and the frit glass joining the panel and funnel is dissolved from the outer side of the bulb. This melting first removes the frit glass (2) protruding from the outer surfaces of the panel (1) and funnel (3), that is, the outer surface of the bulb (4) as shown in FIG. 7 (a). and (b) D
As shown in the figure, this is done until the valve (4) is about 2 mo+ inward from the outer surface. Next, the bulb (4) in which the frit glass (2) has been melted is immersed in hot water and breheated to about 40°C. Thereafter, a shower of cold water at about 20°C is applied to the outer surface of the breheated valve (4).
This is done by applying hot water at 10°C to apply a heat shock to the joint between the panel (1) and the funnel (3), causing cracks to occur in the frit glass (2) at the joint.

The mechanism by which this crack occurs is that the cold water shower causes tension strain on the frit glass on the outer side of the bulb, and micro-cracks are formed starting from defects caused by melting of the frit glass, and these micro-cracks grow larger and progress to the rack. It is said that Particularly in valves consisting of rectangular panels and funnels, the occurrence of these microcracks and the subsequent progression of the cracks are likely to occur at the corners (9) where the largest strain stress occurs, as shown in Figure 9.
) and progresses toward the edge as shown by the arrow (10).

This means that if there is a change in strain stress or an uneven melting amount of frit glass at the joint, the direction of crack propagation will change, causing cracks in the panel or funnel, making it impossible to reuse it. There is. Moreover, the occurrence of cracks in this panel or funnel,
This phenomenon is particularly likely to occur in large color cathode ray tubes, and significantly reduces the bulb regeneration yield.

(Problems to be Solved by the Invention) As described above, the method for recovering color cathode ray tube bulbs involves melting the outside surface of the frit glass bulb that joins the glass panel and the glass funnel, and then This is done by applying a heat shock to the joint with the glass to generate micro-cracks starting from defects caused by melting of the frit glass, and allowing these micro-cracks to progress. However, with this method, if there is a change in strain stress or uneven melting amount of frit glass at the joint between the panel and funnel, the direction of crack propagation changes, causing cracks to occur in the panel or funnel, and reuse. become unable. Moreover, such a problem is particularly likely to occur in large color cathode ray tubes, resulting in a reduction in bulb regeneration yield.

This invention was made in order to solve the above-mentioned problem, and after melting the frit glass that joins the glass panel and the glass funnel, heat shock is applied to the joint, and the panel and the funnel are melted. The purpose of the present invention is to provide a bulb recovery method for color cathode ray tubes that can be recovered at a high yield without damaging panels or funnels.

[Structure of the Invention (Means for Solving the Problems) In a bulb recovery method for a color cathode ray tube consisting of a glass panel and a glass funnel, an outer surface of the bulb of frit glass that integrally joins the panel and the funnel is provided. After melting the side so that the melting surface becomes uneven,
The heat shock caused cracks to occur in the frit glass, thereby separating the panel and funnel.

(Function) As mentioned above, if the outer surface of the frit glass bulb is melted so that the melting surface becomes uneven, stress will be concentrated in the recesses of the melting surface during the subsequent heat shock, causing many microcracks. This allows cracks to propagate starting from these numerous microcracks, suppressing the propagation of cracks to the panel or funnel, and allowing separation without damage.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

As an example, we will discuss the bulb recovery of a color cathode ray tube whose interior is evacuated.

First, a through hole is made in the neck end of the funnel, air is introduced into the tube, and the vacuum is released.

Next, as shown in Fig. 1, the exterior members such as the outer dust coating film provided on the outer surface of the bulb, the explosion-proof metal fittings, and the deflection yoke are removed, and the panel (2) is joined together with the frit glass (2). 1) and a funnel (3), the valve (4) does not have an exterior member. In this state, the frit glass (2) protrudes from the outer surfaces (20P) and (20F) of the panel (1) and funnel (3). (See Figure 7) Furthermore, inside the tube there is a phosphor screen (5), a shadow mask (6), an electron gun (
Various internal pipe members such as (not shown) are arranged.

Next, as shown in Figure 2, a large number of mesh or slit openings made of polyimide resin with high chemical resistance are placed around the outer periphery of the joint of the valve (4) from which the exterior member has been removed. Attach the member (21) with holes by a method such as gluing, immerse it in a solution containing nitric acid as a main component, such as a 15% by weight nitric acid aqueous solution, and insert the frit glass (2) from the outside surface of the bulb (4). dissolve. When the member (21) with a large number of holes is attached so as to surround the outer periphery of the joint in this way, the melting surface (22) of the frit glass (2) becomes
This is partially blocked by the non-perforated portion of the member (21), resulting in a melting surface with many irregularities. In this case, the frit glass (2) is melted so that the melting surface (22) is approximately 2 mm inward from the outer surface of the bulb (4).

Next, similarly to the conventional collection method, the bulb (4) in which the frit glass (2) has been dissolved is immersed in hot water for about 4 hours.
After heating the bulb (4) to 0°C, sprinkle cold water of about 20°C on the outer surface of the bulb (4), which has been heated to 0°C.
Sprinkle with warm water at
), and as shown in Figure 3, the frit glass (2) at the joint is exposed to the arrow (24
4(a) and ().
Separate into panel (1a) and funnel (3a) shown in b). This noknel (la) and funnel (3a)
Frit glass (2) is adhered to the joint end surfaces of the two.

Next, remove the inner tube members from the separated panel (la) and funnel (3a), and then immerse them in the same solution as above to dissolve the frit glass (2) bonded to each joint end surface. Then, as shown in FIGS. 5(a) and 5(b), the panel (1) and funnel (3) are reproduced.

By the way, if the melting surface (22) of the frit glass (2) is made uneven as described above and a heat shock is applied to the joint, the frit glass (2) will melt as shown in FIG.
) The stress of the heat shock concentrates on the recesses (25) of the melting surface (22), and the arrow (
As shown in 24), many microcracks can be generated. Therefore, even if the micro-cracks develop, they can be prevented from reaching the panel (1) and the funnel (3).
) can be separated without damage.

For example, in the case of a 32-inch color cathode ray tube, the bulb failure rate was approximately 30% using conventional recovery methods.
The method of this example was able to reduce the failure rate to 5%.

[Effect of the invention] If the outside surface of the bulb of the frit glass that integrally joins the glass panel and the glass funnel is melted so that the melting surface becomes uneven, the concave portions of the melting surface will become uneven during the subsequent heat shock. Stress is concentrated to generate a large number of microcracks, and the cracks propagate from these microcracks as starting points, making it possible to separate panels and funnels without damaging them, greatly improving valve remanufacturing yields. can.

[Brief explanation of the drawing]

1 to 5 are detailed explanatory diagrams of the present invention.
Figures (a) and (b) are diagrams for explaining the method of melting the frit glass that joins the panel and funnel, respectively, and Figure 3 shows the cracks in the joint that occur due to heat shock after melting the frit glass. Diagrams for explanation: Figures 4(a) and (b) are diagrams of panels and funnels separated by heat shock, and Figures 5(a) and (b) are diagrams of recovered panels and funnels, respectively. , Fig. 6 is a diagram showing the structure of a color cathode ray tube, Fig. 7 is a diagram showing the joint between the panel and funnel of a color cathode ray tube bulb to be collected, and Fig. 8 (a)
) and (b) are diagrams for explaining the conventional method of melting the frit glass that joins the panel and funnel, respectively, and Figure 9 shows cracks in the joint that occur due to heat shock after melting the conventional frit glass. FIG. 1... Panel 2... Frit glass 3.
... Funnel 4 ... Valve 21 ... Member with many openings

Claims (1)

[Scope of Claims] For a bulb formed by integrally joining a glass panel and a glass funnel with frit glass, after dissolving the outside surface of the bulb of the frit glass with a solution containing nitric acid as a main component, In a color cathode ray tube bulb recovery method in which cracks are generated in the frit glass by heat shock to separate the panel and the funnel, the outside surface of the bulb of the frit glass is melted so that the melting surface becomes uneven. Characteristic color cathode ray tube bulb recovery method.