JPH07142013A - Glass bulb for cathode-ray tube - Google Patents

Abstract

PURPOSE:To minimize shrinkage deformation due to cooling solidification by providing compressive stress layers of predetermined thicknesses in the external surface and the internal surface of the face part and the skirt part of a glass panel and appropriately selecting the stress value. CONSTITUTION:Compressive stress layers 22, 23 having thicknesses of not less than 1/10 of the glass thickness are provided on the outside and the inside of the face part and the skirt part of a glass panel 3. Then the value of a compressive stress in the external surface of the face part 7 is made larger than or nearly equal to the value of a compressive stress in the internal surface of the face part 7. With this constitution, the deformation of glass such as twist can be stably and surely prevented and when it is used for the CRT of a color TV, the extremely highly accurate scanning of electron beams can be performed to improve image quality.

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 (cathode ray tube) used in a television or the like, and more particularly to a reinforced structure of a glass panel constituting the display screen side thereof.

More specifically, in a cathode ray tube that requires extremely precise dimensions such as a color picture tube having a color selection mechanism such as a shadow mask, when the glass is physically strengthened to improve the surface strength of the glass, the glass dimension 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 molded and then cooled to shrink to form a compressive stress layer on the surface. There is.

In this physical strengthening, when the glass is rapidly cooled from a high temperature region near the softening point, the surface rapidly shrinks and solidifies, while the interior still retains sufficient fluidity and remains expanded and temporarily distorted. It alleviates instantly. Upon further cooling, the interior will also try to shrink, but its movement is limited by the presence of the solidified surface layer.

As a result, when the temperature of the glass falls 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 fall from the annealing point to the strain point, and the faster the cooling, the larger the difference in shrinkage with the interior, and the larger the surface after cooling. 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 controlling the cooling rate of each portion.

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

Conventionally, in this cooling process, a method of cooling and solidifying the skirt portion faster than the face portion has been adopted. Therefore, as described in, for example, USP 4,566,893, compression formed on the skirt portion is performed. The stress value was 1.5 to 3 times as large as 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 more strongly and faster than the face portion, when the glass panel is cooled and solidified, a viscous flow is more likely to occur. The face portion is greatly deformed as the skirt portion contracts. Therefore, since the accuracy of the inner surface curvature of the face portion fluctuates and becomes unstable, in the case of a color picture tube using such a glass panel, it causes poor landing characteristics of the electron beam, 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 provides a glass bulb for a cathode ray tube in which the deformation of the face portion due to the shrinking action accompanying the cooling and solidification of the skirt portion of the glass panel is suppressed to a minimum. For the purpose of provision.

[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 which constitutes a display screen and is substantially perpendicular to the face portion from its peripheral portion. A glass panel portion consisting of a skirt portion extending in the direction, a funnel-shaped funnel portion sealingly joined to the glass panel portion, and a neck portion at the base of the funnel portion for housing the 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 that of the compressive stress layer at the skirt.

In a preferred embodiment, 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 inner surface.

[0012]

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

Further, a difference in compressive stress value is provided between the outer surface and the inner surface of the panel face, and a 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]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a cross sectional view of a television cathode ray tube 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 that is hermetically joined to the glass panel portion 3, and a neck portion 5 that houses an electron gun. The glass bulb 2 is composed of The glass panel section 3 is
The image display surface includes a substantially rectangular face portion 7 and a skirt portion 6 extending from the peripheral edge of the face portion 7 in a substantially vertical direction. An explosion-proof reinforcement 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 electron beam irradiation from an electron gun, and an aluminum film 13 for preventing the return of light emission from the fluorescent film 12 are laminated.
Furthermore, a shadow mask 14 that defines the irradiation position of the electron beam is provided on the inner side thereof. The shadow mask 14 is fixed to the inner surface of the skirt portion 6 by stud pins 15.

Such a glass panel portion 3 has a sealing portion 1
It is hermetically joined to the funnel portion 4 by a frit sealing agent or a sealing agent such as solder glass provided on the No. 0. 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 be electrically conductively grounded to the outside.

Glass panel 3 constituting the cathode ray tube 1
After being press-molded by a pressing die, is passed through the slow cooling device to be cooled. 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 outside of the front of the face portion 7, the cooling action of the face portion is made larger than the cooling action of the skirt portion for faster cooling. This makes the magnitude of the compressive stress in the face portion larger than the magnitude of the compressive stress in the skirt portion,
Moreover, 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 indicated by the dotted line in the figure, compressive stress layers 20 and 21 are formed on the outer surface and the inner surface of the face portion 7, respectively. Further, the compressive stress layers 22 and 23 are also formed on the outer surface and the inner surface of the skirt portion 6. Of these compressive stress layers 20 to 23, at least the compressive stress layers 20 and 21 of the face portion 7 have a thickness of 1/10 or more of the glass thickness (thickness of the face central portion), and the compressive stress of the face portion 7 is reduced. 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 portion 6.

Further, the compressive stress layer 2 of the face portion 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 stress on the face portion larger than the stress on the skirt portion and the magnitude of the stress on the outer portion of the face larger than the magnitude of the inner stress, for example, in an annealing device after press molding, cool air is blown from the lower side of the conveying path. With the configuration in which the glass panel is supplied, the panel is placed on the 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 strongest on the outer surface of the face, then on the inner surface of the face, and then on the skirt portion. By physically differentiating the cooling speed of each part of the glass panel as described above, the deformation preventing effect after solidification by cooling is remarkably improved as shown in a sample described later.

Specific examples of the glass panel having the above structure are shown in Table 1 below. Table 1 shows the values of compressive stress at each location on the outer and inner surfaces of the face and skirt of the glass panel for the four types of samples.

[0021]

[Table 1]

Sample-1 is a gradual cooling device for supplying cool air from the lower side of the conveying path as in the above-mentioned example, and the glass panel is placed on the conveying path with the skirt portion facing downward, and the cooling rate of the skirt portion is set. Samples 2 to 4 are samples of the physical strengthening method in which the face portion is on the lower side and the glass panel is placed on the conveying path to accelerate the cooling rate of the face portion.

As is clear from Table 1, the sample-
In No. 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 these sample-2 to sample-4, regarding the compressive stress values of the outer surface and the inner surface of the face part, in sample-2 and sample-3, the stress value of the inner surface is larger than the stress value of the outer surface, −
On the contrary, 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 twist deformation after cooling and solidification for each of the physically strengthened samples shown in Table 1.

[0025]

[Table 2]

The measurement is performed by sampling 100 samples of each of Samples 1 to 4 and measuring an average value of twist and a standard deviation. The twist is measured by measuring the difference in height from the face surface at the center of the panel with respect to the two diagonal lines connecting the skirt ends at the four corners of the glass panel. The reference numeral indicates the direction of twist, and the magnitude of 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 twist and the variation in the distribution is large. 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 greater the twist. It became a result. On the other hand, as in Sample-4, by physically strengthening so that the stress value of the face part is larger than the stress value of the skirt part and the stress value of the face outer surface is larger than the stress value of the inner face surface. As a result, the amount of twist deformation was minimized, and the variation was small, and stable results were obtained.

[0028]

As described above, in the present invention, the compressive stress of the face portion of the glass panel is made larger than the compressive stress of the skirt portion, and the compressive stress value on the outer surface of the face portion is set to the compressive stress value on the inner surface of the face portion. By making it larger (or almost equal), glass deformation such as twisting can be stably and reliably prevented, so extremely high precision electron beam scanning is achieved when it is used in a cathode ray tube of a color TV. Therefore, an excellent effect that the image quality is improved is obtained.

[Brief description of 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 part 7: Face part 20: Compressive stress layer 21: Compressive stress layer 22: Compressive stress layer 23: Compressive stress layer

Claims (2)

[Claims] 1. A glass panel portion comprising a substantially rectangular face portion forming a display screen and a skirt portion extending from the peripheral portion of the face portion in a direction substantially perpendicular to the face portion, and with respect to the glass panel portion. In a glass bulb for a cathode ray tube comprising a funnel-shaped funnel portion which is hermetically joined and a neck portion at the base of the funnel portion which houses an electron gun, an outer surface of a face portion and a skirt portion of the glass panel portion and 1 / 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 the stress value of the compressive stress layer of the face portion is larger than that 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 inner surface.