JPH1186753A - Glass panel for cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass panel for a cathode-ray tube, wherein reduction in weight can be attained, flaw or the like is made difficult to enter into a glass surface, when a glass bulb is exhausted, after it has been exhausted, the generation of damage caused by the glass panel is prevented, even stress loads against the outside atmospheric pressure can be sufficiently endured, mechanical strength is superior. SOLUTION: In this glass panel for a cathode ray tube, a maximum thickness t1 of a curved part 4 transferred to a skirt part 3 from a face part 2, a thickness t2 in a mold match part 3a of the skirt part 3, and a thickness t3 in a seal edge part 3b of the skirt part 3, are provided having a relation t1 >t2 >t3 . In this case, in an inner/outer surface of a glass panel 1 for a cathode ray tube, a compression stress layer C is formed, when assuming σ1 for compression stress value of the curved part 4, σ2 for compression stress value in the vicinity of the mold match part 3a of the skirt part 3, and σ3 for compression stress value in the seal edge part 3b of the skirt part 3, a relation of σ3 >σ2 >σ1 exists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass panel for a cathode ray tube.

[0002]

2. Description of the Related Art A glass panel for a cathode ray tube is formed by supplying a predetermined amount of molten glass lump to a lower mold and pressing the same with an upper mold, and thereafter, is conveyed to a lehr, where a predetermined temperature schedule in the lehr is set. Is gradually cooled according to On the glass panel after the slow cooling, a layer of a compressive stress is formed on the inner and outer surfaces thereof, and a layer of a tensile stress having a magnitude half the absolute value of the compressive stress is formed on an inner layer between them. In general, compressive stress for glass is known to have an effect of making the glass less likely to be scratched and to break the glass.However, such a compressive stress increases as the thickness of the glass increases. Formed. That is, the greater the thickness of the glass, the greater the temperature difference between the surface layer and the inner layer of the glass when the glass is cooled,
As a result, the compressive stress on the inner and outer surfaces of the glass increases.

A glass panel for a cathode ray tube is shown in FIGS.
As shown in FIG. 1, a face portion 2 having an effective screen portion 2a on which an image is projected and a skirt portion 3 extending over the entire circumference of the face portion 2 are usually provided. 1, the maximum thickness of the curved portion 4 that transitions from the face portion 2 to the skirt portion 3 is t ₁ , the thickness of the mold match portion 3 a of the skirt portion 3 during panel molding is t ₂ , and the funnel When the thickness of the seal edge portion 3b serving as a joint end portion between the _{t 3 t 1> t 2>} t
_{There are three} relationships. Therefore, the conventional glass panel 1
Of the compressive stress layer C formed on the inner and outer surfaces of the skirt portion 3, the stress value at the three portions is the largest at the curved portion 4 transitioning from the face portion 2 to the skirt portion 3, and then the mold match portion 3a of the skirt portion 3 and the skirt portion. It is reduced in the order of the seal edge portion 3b of the portion 3.

[0004]

Such a glass panel for a cathode ray tube tends to have fine scratches and the like particularly on the outer surface during the manufacture thereof.
In the subsequent tube process, it causes a breakage of the glass bulb for a cathode ray tube. That is, the glass bulb for a cathode ray tube is formed by joining a funnel and a neck tube to a glass panel for a cathode ray tube, and the inside thereof is evacuated and used as a vacuum vessel. So, for example,
If the above-mentioned minute scratches or the like are present on the outer surface, destruction starting from the scratches occurs with the evacuation of the inside of the glass bulb. Actually, the glass bulb is liable to be broken at the time of evacuation, particularly due to the glass panel. Among them, the glass bulb is most frequent at the sealing edge portion of the skirt portion, which is the joint portion with the funnel, and then the mold match portion of the skirt portion. It is likely to occur in the order of the vicinity, and the curved portion transitioning from the face portion to the skirt portion.

In the glass bulb after exhaust,
Since the external surface is always stressed by the external atmospheric pressure and the glass bulb is non-spherical, the stress distribution of the external atmospheric pressure on the glass bulb is limited by the compression of The stress exhibits a state in which an outward tensile stress is applied to the skirt portion. Since glass is weak in tensile strength,
Even after exhaustion of the glass bulb, there is a problem that implosion is likely to occur due to tensile stress exerting a large force in the region from the vicinity of the mold match portion of the glass panel, particularly from the mold match portion to the seal edge portion.

In order to solve such a problem, it is conceivable to improve the mechanical strength of the glass panel by increasing the thickness of the glass panel. Is not only inconvenient, but also causes an increase in cost, which is not preferable in terms of workability and economy.

Accordingly, an object of the present invention is to reduce the weight,
Glass for cathode ray tubes with excellent mechanical strength that does not easily damage the glass surface, does not cause breakage due to the glass panel during and after evacuation of the glass bulb, and can withstand stress loads against external atmospheric pressure. Is to provide a panel.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems and objects, and has a face portion provided with an effective screen portion on which an image is projected, and extends over the entire circumference of the face portion. consists of a skirt portion which standing, the maximum thickness t ₁ of the curved portion shifts from the face portion to the skirt portion, and the thickness t ₂ of the mold match portion of the skirt portion during panel molding,
In a glass panel for a cathode ray tube, a thickness t ₃ of a seal edge portion of a skirt portion serving as a joint end portion with the funnel has a relationship of t ₁ > t ₂ > t _3. A compressive stress layer is formed on the outer surface, and the compressive stress layer has a compressive stress value of σ _{1 of} a curved portion that transitions from a face portion to a skirt portion, and a portion near a mold match portion of the skirt portion during panel molding. Compressive stress value is σ
_2, and when a compressive stress value of the seal edge portion to become the skirt portion connecting end of a funnel and σ _3, σ _3> σ
Be a _2> sigma ₁ the relationship is a glass panel for a cathode ray tube according to claim.

In the present invention, the mold matching portion of the skirt portion refers to a portion where two molds, a bottom mold and a body mold (shell), which constitute a lower mold, are joined at the time of panel molding. Shall point to.

[0010]

According to the present invention, a compressive stress layer is formed on the inner surface and the outer surface of the glass panel, and the stress value is inversely related to the thickness of the glass at each portion, that is, the sealing of the skirt portion. Edge> Near the skirt part near the mold match> Relationship with a curved part that transitions from the face part to the skirt part. Greater compression is applied to the thin part of the glass panel, which is likely to be damaged during and after the exhaust of the glass bulb. Since the stress is formed, the glass surface is not easily scratched, and the glass valve does not break due to the glass panel during and after evacuation, and can sufficiently withstand the stress load to the external atmospheric pressure. A glass panel for a cathode ray tube having a high strength.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a glass panel for a cathode ray tube according to the present invention will be described based on embodiments.

The drawings will be described with reference to FIGS. 1 and 2 described above.

The 29 type glass panel 1 for a cathode ray tube according to the present embodiment has a face portion 2 having an effective screen portion 2a having a short side of 471.6 mm and a long side of 600.8 mm, and a face 2
, The maximum thickness t ₁ of the curved portion 4 that transitions from the face portion 2 to the skirt portion 3, the thickness t ₂ of the mold match portion 3a of the skirt portion 3 during panel molding, and the skirt. Thickness t ₃ of the seal edge portion 3b of the portion ₃
Are t ₁ = 20.0 mm, t ₂ = 17.0 mm, t
₃ = 10.6 mm.

A compressive stress layer C is formed on the inner surface and the outer surface of the glass panel 1 for a cathode ray tube, and the compressive stress value σ of the curved portion 4 transitioning from the face portion 2 to the skirt portion 3.
₁ is 80 kg / cm ² , and the compressive stress value σ _{2 in the} vicinity of the mold match portion 3 a of the skirt portion 3 during panel molding is 100 k
g / cm ² , and the compressive stress value σ ₃ of the seal edge portion 3b of the skirt portion 3 serving as a joint end portion with the funnel is 120 kg.
/ Cm ² .

The glass panel 1 for a cathode ray tube was manufactured as follows.

After the molten glass ingot is pressed and molded into a glass panel 1, before it is carried into a lehr, only the mold match portion 3a and the seal edge portion 3b of the skirt portion 3 of the glass panel 1 are heated by a burner device. . No special heating was performed on the curved portion 4 that transitions from the face portion 2 to the skirt portion 3 of the glass panel 1. As a result, in the glass panel 1 immediately before being carried into the lehr, the face portion 2 is set at 450 ° C. and the mold match portion 3a is set at 50 ° C.
0 ° C., the seal edge 3b is maintained at 520 ° C., and is conveyed to a lehr where the maximum temperature is set to 480 ° C., and is gradually cooled.
Cooled to room temperature.

The glass panel 1 thus obtained and a conventional glass panel obtained by directly carrying it into a lehr after press molding were subjected to a strength test by the following method.

First, 20 glass panels 1 of the present embodiment and a conventional glass panel were prepared respectively, and a funnel and a neck were joined to form a glass bulb. After evacuation, the entire outer surface of the glass panel was subjected to No. 150 abrasion. Was given. Next, the glass bulb was heated to 400 ° C. at 5 ° C./min, and
After maintaining for 5 minutes, the temperature was lowered at a rate of 20 ° C./minute, and then a down shock destruction test was performed.

As a result, in the conventional glass bulb using the glass panel, seven breakage occurs from the seal edge portion, and four breakage occurs near the mold match line. Although the bulb was damaged, the glass bulb using the glass panel 1 of this example was not damaged at all, and good results were obtained.

[0020]

As described above, the glass panel for a cathode ray tube according to the present invention can be reduced in weight, the surface of the glass is hardly damaged, and the glass bulb is evacuated and exhausted when the glass bulb is evacuated.
This provides an excellent effect of not causing breakage due to the glass panel portion and having mechanical strength enough to withstand a stress load to the external atmospheric pressure.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a glass panel for a cathode ray tube.

FIG. 2 is a partially enlarged explanatory view of a glass panel for a cathode ray tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass panel for cathode ray tubes 2 Face part 2a Effective screen part 3 Skirt part 3a Mold match part 3b Seal edge part 4 Curved part C Compressive stress layer

Claims (1)

[Claims] 1. A maximum thickness of a curved portion that includes a face portion provided with an effective screen portion on which an image is projected and a skirt portion extending over the entire circumference of the face portion, and transitions from the face portion to the skirt portion. The thickness t ₁ , the thickness t ₂ of the mold match portion of the skirt portion at the time of panel molding, and the thickness t ₃ of the seal edge portion of the skirt portion to be a joining end with the funnel are t ₁ > t ₂ > t. _{In the} glass panel for a cathode ray tube having the relationship of ₃ , a compressive stress layer is formed on an inner surface and an outer surface of the glass panel for a cathode ray tube, and the compressive stress layer shifts from the face portion to the skirt portion. The compressive stress value of the curved portion is σ ₁ , the compressive stress value of the skirt portion near the mold match portion at the time of panel molding is σ ₂ , and the compressive stress value of the seal edge portion of the skirt portion which is the joining end with the funnel is σ ₃ that when σ _3> σ _2> σ cathode ray tube glass panel characterized by comprising a ₁ the relationship.