JP2636707B2 - Glass bulb for cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass bulb for a cathode ray tube (CRT) used in a television or the like, and more particularly to a strengthened structure of a glass panel constituting a display screen side thereof.

More specifically, in a cathode ray tube requiring extremely precise dimensions, such as a color picture tube incorporating a color selection mechanism such as a shadow mask, when performing physical strengthening to improve the surface strength of the glass, And a glass panel structure having a practically high compressive stress distribution with high strength.

[0003]

2. Description of the Related Art In order to increase the mechanical strength of a glass bulb for a cathode ray tube against impact or the like, a physical strengthening method has been conventionally used in which a glass panel is formed and then cooled to contract to form a compressive stress layer on the surface. I have.

[0004] In this physical strengthening, when the glass is rapidly cooled from a high temperature region near the softening point, the surface shrinks and solidifies rapidly, but the inside still retains sufficient fluidity and remains in an expanded state. Instantly relaxed. Upon further cooling, the interior also tends to shrink, but its movement is limited by the presence of a solidified surface layer.

As a result, when the temperature of the glass drops to room temperature and reaches a sufficient equilibrium state, a large compressive stress layer is formed on the surface and a tensile stress layer is formed inside, and remains as residual stress. The magnitude of the stress generated at this time depends on the time required for the glass surface to decrease from the annealing point to the strain point, and the faster the cooling is, the larger the difference in shrinkage from the inside becomes, and the larger the surface becomes after cooling is completed. Generates compressive stress.
Therefore, when strengthening a structure such as a substantially rectangular glass panel having a face portion and a skirt portion, a desired stress distribution can be obtained by manipulating the cooling rate of each portion.

Regarding a glass panel for a color picture tube,
Usually, a lump of molten glass at a temperature of about 1000 ° C. to 1100 ° C. is supplied into a receiving mold, press-formed by a pressing die, and then a stud pin is sealed to an inner wall of a predetermined skirt portion. At this stage, the temperature has almost reached the temperature near the annealing point, but by operating the cooling method up to the strain point thereafter, the above-mentioned physical strengthening can be obtained.

Conventionally, in this cooling process, a method of cooling and solidifying the skirt portion faster than the face portion has been adopted. Therefore, for example, as described in US Pat. No. 4,566,893, the compression formed on the skirt portion has been performed. The stress value was as large as about 1.5 to 3 times the compressive stress value of the face portion.

[0008]

However, in the physical strengthening by the conventional cooling method in which the skirt portion is cooled stronger and faster than the face portion, when the glass panel is cooled and solidified, a temperature range in which a viscous flow is more likely to occur is obtained. The face portion undergoes a large deformation with the movement of the skirt portion when it contracts. Therefore, since the accuracy of the curvature of the inner surface of the face portion fluctuates and becomes unstable, in the case of a color picture tube using such a glass panel, the landing characteristic of the electron beam becomes poor and a stable color image cannot be obtained. .

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is directed to a glass bulb for a cathode ray tube in which the deformation of the face portion due to the shrinkage effect of the cooling and solidification of the skirt portion of the glass panel is minimized. For the purpose of providing.

[0010]

In order to achieve the above object, a glass bulb for a cathode ray tube according to the present invention has a substantially rectangular face portion constituting a display screen, and the face portion is substantially perpendicular to a peripheral portion thereof. A glass panel portion comprising a skirt portion extending in the direction, a funnel-shaped funnel portion hermetically joined to the glass panel portion, and a neck portion at the root of the funnel portion for storing an electron gun. In the glass bulb for a cathode ray tube, a compressive stress layer having a thickness of 1/10 or more of the glass thickness is formed on the outer surface and the inner surface of the face portion and the skirt portion of the glass panel portion, and the compressive stress of the face portion is formed. The stress value of the layer is larger than the stress value of the compressive stress layer of the skirt.

[0011] In a preferred embodiment, the stress value of the compressive stress layer on the outer surface of the face portion is smaller than that of the inner surface.
It is characterized in that it is larger or almost equal to the stress value of the force layer .

[0012]

[Function] By cooling the face portion faster than the skirt portion of the glass panel to form a compressive stress layer, the deformation of the face portion due to the shrinkage and solidification of the skirt portion is suppressed, and the curvature of the face inner surface more than twice that of the conventional case. Improved accuracy can be achieved.

Further, a difference is provided in the compressive stress value between the outer surface and the inner surface of the panel face, and the compressive stress layer is formed so that the outer stress value is equal to the inner stress value or the outer stress value is larger. The formation further enhances the effect of preventing face deformation.

[0014]

FIG. 2 is a sectional view showing the construction of a cathode ray tube for television to which the present invention is applied. The cathode ray tube 1 basically includes a glass panel portion 3 on the image display surface side, a funnel-shaped funnel portion 4 hermetically bonded to the glass panel portion 3, and a neck portion 5 containing an electron gun. And a glass bulb 2 composed of The glass panel unit 3
It comprises a substantially rectangular face portion 7 constituting an image display surface, and a skirt portion 6 extending in a substantially vertical direction from a peripheral portion of the face portion 7. An explosion-proof reinforcing band 8 is wound around the outer periphery of the skirt portion 6 to maintain panel strength and prevent scattering at the time of breakage. On the inner surface side of the face portion 7, a fluorescent film 12 that emits fluorescence by irradiating an electron beam from an electron gun, and an aluminum film 13 for preventing light emission from returning from the fluorescent film 12 are laminated.
Further, a shadow mask 14 for defining the irradiation position of the electron beam is provided on the inner side. The shadow mask 14 is fixed to the inner surface of the skirt 6 by stud pins 15.

The glass panel section 3 has the sealing section 1
The sealing member is sealed to the funnel portion 4 by a sealing agent such as a frit sealing agent or a solder glass provided at the bottom. An inner coating 16 is provided on the inner side of the funnel portion 4 to prevent the shadow mask 14 from being highly charged by an electron beam and to conduct conductive grounding to the outside.

Glass panel 3 constituting the cathode ray tube 1
Is cooled by passing through a slow cooling device after press molding with a pressing die. In this cooling step, the glass panel is solidified and a compressive stress layer is formed on the surface of the glass panel. In the present invention, for example, by mainly applying cooling air from the front outside of the face portion 7, the cooling effect of the face portion is made larger than the cooling effect of the skirt portion, thereby cooling the face portion faster. Thereby, the magnitude of the compressive stress of the face part is made larger than the magnitude of the compressive stress of the skirt part,
Further, the magnitude of the compressive stress on the outer surface of the face portion is made larger than the magnitude of the compressive stress on the inner surface.

FIG. 1 is a sectional view of a glass panel 3 of a cathode ray tube according to the present invention. As shown by the dotted lines in the figure, the compressive stress layers 20 and 21 are formed on the outer surface and the inner surface of the face portion 7, respectively. The compressive stress layers 22 and 23 are also formed on the outer surface and the inner surface of the skirt portion 6. At least the compressive stress layers 20 and 21 of the face portion 7 among these compressive stress layers 20 to 23 have a thickness of 1/10 or more of the glass thickness (thickness of the face central portion), and the compression of the face portion 7 The stress values of the stress layers 20 and 21 are larger than the stress values of the compressive stress layers 22 and 23 of the skirt 6.

The compressive stress layer 2 of the face 7
Regarding 0 and 21, it is desirable that the stress value of the outer stress layer 20 be larger than the stress value of the inner stress layer 21.
In this way, in order to make the face stress larger than the skirt stress and make the face outer stress larger than the inner stress, for example, in a slow cooling device after press molding, cool air is supplied from the lower side of the conveyance path. In this configuration, the glass panel is placed on a transport path with the face surface of the glass panel facing downward, and passed through the slow cooling device.

As a result, the strength of the cooling action is highest on the outer face of the face, then on the inner face of the face, and then on the skirt. As described above, by providing a difference in the cooling speed of each part of the glass panel to physically strengthen the glass panel, the effect of preventing deformation after cooling and solidification is extremely improved, as shown in a sample described later.

Table 1 below shows specific examples of the glass panel having the above structure. Table 1 shows the compressive stress values of the four types of samples at the outer surface and the inner surface of the face and skirt of the glass panel.

[0021]

[Table 1]

Sample 1 is a slow cooling device for supplying cool air from the lower side of the transport path as in the above-described example. A glass panel is placed on the transport path with the skirt section down, and the cooling rate of the skirt section is reduced. This is a sample of the physical strengthening method in which the cooling rate of the face portion was increased by placing the glass panel on the transport path with the face portion facing down from Sample-2 to Sample-4.

As is clear from Table 1, the sample-
In 1, the stress value of the skirt portion is larger than the stress value of the face portion on both the outer surface and the inner surface. On the other hand, in Sample-2 to Sample-4, the stress value of the face portion is larger than the stress value of the skirt portion on both the outer surface and the inner surface. Regarding the compressive stress values of the outer surface and the inner surface of the face portion of Sample-2 to Sample-4, in Sample-2 and Sample-3, the stress value of the inner surface was larger than the stress value of the outer surface. −
In No. 4, the stress value on the outer surface is larger than the stress value on the inner surface.

Table 2 below shows the measurement results of the torsional deformation after cooling and solidification of each of the samples subjected to the physical strengthening shown in Table 1.

[0025]

[Table 2]

In the measurement, 100 samples were sampled for each sample-1 to 4, and the average value and the standard deviation of the torsion were measured. The torsion is measured by measuring the difference in height from the face at the center of the panel with respect to two diagonal lines connecting the ends of the skirt at the four corners of the glass panel. The sign indicates the direction of the twist, and the magnitude of the twist is indicated by its absolute value. The greater the absolute value, the greater the degree of twist deformation.

As can be seen from Table 2, Sample-1
Has the largest torsion, and the distribution varies greatly. Further, as can be seen from the comparison between Sample-2 and Sample-3, when the compressive stress value on the inner surface of the face is higher than the compressive stress value on the outer surface, the higher the compressive stress, the smaller the variation but the larger the torsion. The result was. On the other hand, by performing physical strengthening such that the stress value of the face portion is larger than the stress value of the skirt portion and the stress value of the outer surface of the face is larger than the stress value of the inner surface of the face as in sample-4. In addition, the amount of torsional deformation was minimized and the variation was reduced, and a stable result was obtained.

[0028]

As described above, according to the present invention, the compressive stress at the face of the glass panel is made larger than the compressive stress at the skirt, and the compressive stress at the outer surface of the face is changed to the compressive stress at the inner surface of the face. By making it larger (or almost equal), it is possible to stably and surely prevent glass deformation such as twisting, so that when used in a cathode ray tube of a color television, etc., extremely accurate electron beam scanning is achieved. Thus, an excellent effect that the image quality is improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a physically strengthened state of a glass panel for a cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a sectional view of a cathode ray tube to which the present invention is applied.

[Explanation of symbols]

 3: Glass panel 6: Skirt portion 7: Face portion 20: Compressive stress layer 21: Compressive stress layer 22: Compressive stress layer 23: Compressive stress layer

Claims (2)

(57) [Claims] 1. A glass panel comprising: a substantially rectangular face constituting a display screen; and a skirt extending substantially vertically from a peripheral portion of the face, and a glass panel comprising: In a glass bulb for a cathode ray tube constituted by a funnel-shaped funnel part hermetically joined and a neck part at the root of the funnel part for storing an electron gun, the outer surface of the face part and the skirt part of the glass panel part and 1 / of the glass thickness on the inner surface
A glass bulb for a cathode ray tube, wherein a compressive stress layer having a thickness of 10 or more is formed, and a stress value of the compressive stress layer of the face portion is larger than a stress value of the compressive stress layer of the skirt portion. 2. The glass bulb for a cathode ray tube according to claim 1, wherein the stress value of the compressive stress layer on the outer surface of the face portion is larger than or substantially equal to the stress value of the compressive stress layer on the inner surface.