KR100468423B1 - The Flat Type C-CRT - Google Patents

Abstract

The present invention relates to a rail shape for a flat brown tube, wherein the inner and outer surfaces having phosphor screens on the inner surface are flat, the funnel connected to the panel, and the phosphor screen on the inner surface of the panel are disposed at regular intervals to serve as color screening. In the flat CRT tube including a shadow mask and a rail attached to the inner surface of the panel for holding and fixing the shadow mask, the rail is formed in the step of extending the direction of the rail on the surface in contact with the panel in the step shape The inner leg and the outer leg are divided by the groove, and the length of the inner leg and the outer leg are different from each other.

The present invention has the effect of dispersing the stress concentrated in the corner portion by filling the fritted glass between the outer leg of the rail and the panel, and reducing the failure rate due to cracks when passing through the furnace process after the PRA production is completed. .

Description

Flat CRT {The Flat Type C-CRT}

The present invention relates to a flat CRT, and more particularly to a flat CRT which improves panel cracking problems during the manufacturing process by modifying the shape of the rail.

In the conventional flat CRT, as shown in FIG. 1, R, G, and B fluorescent films 2 are coated on the inner surface, and a panel 1 having explosion-proof glass is fixed on the front surface thereof. At the rear end, the funnel 6 is fused with fritted glass. In addition, the fluorescent film emits color by the electron beam 9 emitted from the electron gun inserted into the neck portion 8 of the funnel. Inside the panel, a rail 5 capable of supporting the shadow mask 3 and the inner shield 7 is fused by the fritted glass 4. The shadow mask 3 has a plurality of holes formed in the inner surface to pass the electron beam, and is mounted at regular intervals from the inside of the panel. The shadow mask is thermally expanded by the electron beam emitted from the electron gun, which causes the shadow mask to deform. Therefore, in order to prevent deformation of the shadow mask due to thermal expansion, the shadow mask is tensioned and welded to the rail. In addition, the inner shield (7) for shielding the cathode ray tube is less affected by the external geomagnetic is welded to the rail.

Conventional rails are composed of two long side rails 5a and two short side rails 5b as shown in FIG. 2a, and grooves are formed in the extension direction of the rails on the surfaces contacting the panels as shown in FIGS. 2b and 2c. The long side rails 5a and the short side rails 5b have the same shape only in length. The inner and outer legs of the rail are the same length (a = b, a '= b').

The rails are automatically supplied by the automatic welding machine, and then the position of the rail is welded with a laser to form a rectangular frame shape. At this time, the groove is formed on the surface welded to the panel, the liquid glass frit glass is applied to the groove and dried, and then passed through a high-temperature furnace of about 400 ℃ in contact with the inner surface of the panel and the rail Fusion. When the thickness of the upper end of the fused rail is polished to a desired amount by a desired dimension, and the shadow mask is welded on the laser, a single assembly including the rail and the panel is made. However, in the frit glass coating process, due to the temperature difference between the photoresist, the graphite, the phosphor, and the panel-rail assembly and the temperature difference between the various injection liquids, a strong thermal stress is generated at the contact portion between the panel and the rail attached to the inner surface of the panel. Is likely to develop into.

The panel-rail assembly is then passed through a high temperature furnace of about 400 ° C. and fused with a funnel using fritted glass as shown in FIGS. 3A to 3B. However, at this time, another thermal stress is generated between the funnels made of glass, and thus a greater stress is applied to the corners of the rails, thereby increasing the possibility of cracking.

As described above, in the manufacturing process of the CRT having a flat inner surface and an outer surface of the panel, stress due to temperature change is inevitably generated. In particular, the conventional rail, which serves to maintain a constant distance between the shadow mask and the fluorescent film, generates 15% of cracks in the manufacturing process.

The factor that most affects the cracks generated between the stainless rails and the glass panels is a thermal change acting externally. When heat is applied to the rail and the panel, both of them undergo thermal expansion. Since the thermal expansion of the panel and the glass is different from each other, when the external thermal shock is strong, cracks do not endure the thermal stress. This stress imbalance is also prominent at the corners, the fusion points of the rail assemblies. 4 is a diagram showing the stress imbalance in the panel. As shown in the drawing, tensile stress is applied at the center of the panel, and tensile stress and compressive stress cross at the corners, and the rail assembly fusion of the panel cannot withstand such stress. Cracks will occur.

In addition, the amount of fritted glass applied to the rail groove portion also affects the crack of the panel. The larger the amount, the smaller the volume of the rail groove portion is. However, the conventional rail structure prevents the fritted glass from flowing down and at the same time does not form a groove portion that is advantageous to reduce the occurrence of cracks.

Accordingly, an object of the present invention is to provide a flat CRT tube that prevents cracks by compensating for the difference in thermal expansion between the panel and the rail by deforming the shape of the rail.

1 is a cross-sectional view of a flat CRT tube of the prior art.

Figure 2a to 2c is a view showing a rail structure of the prior art.

3a to 3b are detailed views showing the rail structure of the prior art.

4 is a diagram showing a stress distribution of a panel with a rail of the prior art.

5 is a view showing a rail structure of the present invention.

6 is a view showing a shape in which a rail of the present invention is attached to a panel.

7 is a view showing another embodiment of the present invention.

8a to 8d are views illustrating a process of attaching a rail of the present invention to a panel.

*** Explanation of symbols for the main parts of the drawing ***

1 panel 3 shadow mask

5: Rail 5a: Long side rail

5b: Short rail 6: Funnel

The technical means of the present invention for achieving this object is a panel having a flat inner and outer surfaces having a phosphor screen on the inner surface, a funnel connected to the panel, and arranged at regular intervals with respect to the phosphor screen on the inner surface of the panel to serve as color screening. In the flat CRT tube including a shadow mask and a rail attached to the inner surface of the panel for holding and fixing the shadow mask, the rail is formed in the step of extending the direction of the rail on the surface in contact with the panel in the step shape The inner leg and the outer leg are divided by the groove, and the length of the inner leg and the outer leg are different from each other.

Preferably, the outer leg is smaller than the inner leg.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

Since the manufacturing process of CRT passes through the high temperature furnace in some processes, the joint part of CRT always bears the risk of thermal stress, especially in PRA (Panel Rail Assembly) furnace process where the rail and panel are bonded. Due to the difference in thermal expansion coefficient between the rail and the metal, there is a high probability of crack failure due to thermal stress in the area where the panel and the rail are fused.

Therefore, the present invention has devised a rail shape that allows frit glass to act as a buffer between the rail and the panel in order to reduce the difference in thermal expansion between the panel and the rail as described above. That is, the rail of the present invention, as shown in Figure 2a, the length of the long side rail (5a) and the short side rail (5b) is different, but the same shape, but as shown in Figure 5 the length of the outer leg of the rail Shorter than the legs (c <d) to ensure space between the outer leg and the panel. The rail assembly thus constructed is fused to the panel as shown in FIG. 6, and in the PRA state, the inner leg of the rail touches the panel, but the relatively short outer leg does not contact the panel. The fritted glass is filled between the panels to provide a cushioning effect.

In addition, in order to reduce crack defects, the stress concentrated on the corner portion must be dispersed, and the more fritted glass around the corner portion, the more effectively the stress can be dispersed. Therefore, by increasing the height of the outer leg of the rail as in the present invention, when the rail is fused to the panel, the frit glass flows well to the outside, and thus the frit glass can be distributed in the corner portion.

7 is another embodiment of the present invention, as shown in the form of the rail of the present invention can be modified in the form of the form of the rail with the rail to reduce the occurrence of crack failure by reducing the contact area between the panel and the rail. . In other words, the thickness of the inner leg of the rail is reduced to minimize the contact surface between the panel and the rail, and the thermal stress difference between the panel and the rail is filled by filling the fritted glass between the outer leg of the rail and the panel so that the outer leg of the rail does not touch the panel. Can be reduced.

Referring to the effect of the rail of the present invention in detail with the manufacturing process as follows. First, fritted glass is applied to the rail assembly of the present invention as shown in FIGS. 8A and 8B. The rail assembly coated with fritted glass is put into an R / S furnace after drying. At this time, the low-melting glass frit glass begins to melt as shown in FIG. 8C in a furnace rising to about 440 ° C, and the PRA passing through the furnace is outside the inner leg due to the difference in the inner and outer legs of the rail as shown in FIG. 8D. Since the frit glass is distributed in the leg side and the frit glass distribution in the corner part is also increased, it is possible to disperse the stress concentrated on the corner part after the PRA production is completed by buffering action to solve the thermal stress applied during the furnace process.

TABLE 1

[Crack Generation Quantity / Sample Quantity]

Conventional The present invention Rail structure of Figure 3a Rail structure of Figure 3b PRA Production Furnace Process 14/40 11/40 0/40 Furnace process after making PRA 11/26 4/29 2/40

Table 1 shows the crack failure rate of the conventional rail and the rail of the present invention, as can be seen in Table 1, the crack failure rate is reduced by about 70% compared to the conventional rail structure.

As described above, the present invention distributes about 50% of the stress concentrated at the corners of the rail compared to the prior art by shortening the outer legs of the rails, and eliminates crack-related defects when passing through the furnace process after the PRA is completed. It is effective to reduce by%.

Claims (2)

A panel having an inner and outer surface having a phosphor screen on an inner surface thereof, a funnel connected to the panel, a shadow mask disposed at a predetermined interval with respect to the phosphor screen on the inner surface of the panel to serve as color screening, and the shadow mask being fixedly supported In a flat CRT comprising a rail attached to an inner surface of a panel for The rail is provided with a groove portion formed in the extending direction of the rail on the surface in contact with the panel, divided into the inner leg and the outer leg by the groove portion, the plane characterized in that the length of the inner and outer legs are different from each other CRT. The method of claim 1, Flat brown tube, characterized in that the outer leg is smaller than the inner leg.