JP2002358911A - Glass panel for cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality glass panel with excellent heat resistance by preventing generation of damage such as triangular cracking at a glass panel for a cathode-ray tube having a flattened face part. SOLUTION: With the panel for the cathode-ray tube provided with a face part with curvature radius on the outer surface on the diagonal axis X not less than 10,000 mm, a concave part 10 is formed in the region including at least diagonal axis at a sealing end face 5 of a skirt part 6. The concave part 10 is preferably formed in the range of not less than 5 mm to not more than 100 mm toward the center part in the length direction of a sealing end face of each side part 8 from a diagonal axis X at the sealing end face 5.

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, and more particularly to a technique for suppressing breakage of the glass panel during a heat treatment in a cathode ray tube manufacturing process.

[0002]

2. Description of the Related Art As is well known, a cathode ray tube includes, as main glass parts, a panel on which an image is projected and a funnel-shaped funnel. As shown in FIG. 4, the panel 1 has a substantially rectangular face portion 3 provided with an effective screen for displaying an image, and is connected to the face portion 3 via a blend R portion 4 and is used for bonding to the funnel. Sealed end face 5
And a skirt portion 6 having the following. And
The skirt portion 6 includes each side portion 8 between the four diagonal portions 7, and a mold match line 9 which is generated by matching of a press molding die of the panel 1 and becomes a maximum outer diameter portion of the panel 1. have.

[0003] Generally, in the molding step of this type of glass panel 1 for a cathode ray tube, a high-temperature molten glass lump is supplied to a molding die, and a plunger is lowered to spread the molten glass lump in the molding die. After that, the plunger is raised. After the completion of this molding step, predetermined functions or steps including cooling and the like are performed, whereby the glass panel 1 for a cathode ray tube shown in FIG.

In the production of a color cathode ray tube,
Solder glass (hereinafter, referred to as frit glass) is interposed between the sealing end face 5 of the skirt portion 6 of the panel 1 and the sealing end face of the funnel opposed thereto to seal the panel 1 and the funnel. Is performed. The glass bulb for a cathode ray tube manufactured in this manner is used as a cathode ray tube which is a vacuum vessel by evacuating the inside to a vacuum. In addition, a stress due to a difference in pressure between the inside and the outside is applied to an outer surface of the glass bulb which functions as an envelope of the cathode ray tube. Therefore, the shape, thickness, and the like of the glass bulb used in the cathode ray tube are designed to withstand this stress.

In particular, in a glass tube for a cathode ray tube manufactured by sealing the panel 1 and the funnel with frit glass, when the inside of the cathode ray tube is formed under a high vacuum, atmospheric pressure is applied to the cathode ray tube. Since the vacuum stress generated by the sealing is maximized at the sealing end face between the panel 1 and the funnel, the sealing strength of the panel 1 and the funnel is adjusted so that the sealing strength necessary to withstand the vacuum stress is obtained. The wall thickness is determined. Further, the sealing end face 5 of the panel 1
Each side portion 8 and each diagonal portion 7 are so arranged that a sufficient sealing strength between the panel 1 and the funnel by frit glass can be obtained.
Are all flat surfaces.

Therefore, the area from the mold match line 9 to the sealing end face 5 in the skirt portion 6 of the panel 1 is
The dimension in the direction parallel to the tube axis Z (hereinafter, referred to as the tube axis parallel direction) is set to be the same over the entire circumference. In other words, the dimension in the direction parallel to the tube axis from the mold match line 9 of each side 8 of the skirt portion 6 of the panel 1 to the sealing end face 5 is h _0, and the mold match on the diagonal axis X at the diagonal portion 7 if the dimensions of the tube axis direction parallel leading to the seal end face 5 from the line 9 and h _1, a h ₀ = h _1.

When forming the sealing end face 5 of the panel 1, a press die corresponding to the sealing end face 5 is formed flat, and a sealing end face having a desired flatness is formed by press molding. Forming is performed as an example. Separately from this, particularly in a large panel, a desired flatness may not be obtained due to thermal deformation after panel molding.In such a case, by polishing the sealing end face in a later step, Another example is to form a sealing end surface having a desired flatness.

[0008]

In recent years, flattening of the outer surface of the face portion of the panel 1 has been promoted, and the radius of curvature of the outer surface on the diagonal axis X is 10,000.
A panel 1 (hereinafter, referred to as a flat panel in this section) having a face portion 3 that forms an effective screen of not less than 1 mm has been manufactured. When this flat panel 1 becomes a component of the glass bulb for a cathode ray tube described above,
The stress due to the difference between the inside and outside air pressures applied to the face portion 3 is significantly larger than that of a curved panel (a panel which occupied the mainstream before the flat panel 1 became popular). For this reason, the face portion 3 of the flat panel 1
Is generally set to be thicker than the thickness of the sealing end face 5.

In this case, in the step of sealing the flat panel 1 and the funnel for manufacturing a glass bulb for a cathode ray tube, frit glass is interposed between the sealing end face 5 of the flat panel 1 and the sealing end face of the funnel. By exposing it to the internal atmosphere of a heat treatment furnace having a maximum temperature of about 450 ° C., a chemical bond is generated by reacting the sealing end faces of the two with the frit glass.

In the heating process in the sealing step, the face portion 3 of the flat panel 1 is substantially rectangular and the outer surface thereof is flattened. , Different thermal expansion deformation occurs, and thermal stress concentration occurs on the outside of the diagonal portion 7 of the sealing end face 5 in the flat panel 1. In this case, if a defect such as a minute flaw is present at the diagonal portion 7 of the sealing end face 5, particularly at the outer portion, a crack originating from the defect occurs due to the concentration of thermal stress, and this crack is generated. Progresses in the process of raising the temperature, damage occurs in the shape of a triangular pyramid from the sealing end face 5 of the diagonal portion 7 or the periphery thereof to each side portion 8, and a phenomenon called a so-called triangular crack occurs.

The drawbacks such as minute scratches are that when the flat panel 1 after molding is handled, for example, when the surface of the flat panel 1 is polished, the flat panel 1 is brought into contact with the sealing end face 5 on a predetermined table. In the process of fixing the flat panel 1 or in the package when the flat panel 1 is packed and transported, or in various transporting steps of the flat panel 1, etc., due to contact or sliding between the sealing end face 5 and other members. is there. Then, even if the minute scratches and the like are of such a degree that they cannot be easily observed visually, there is a fear that damage such as a triangular crack may be induced due to the above-mentioned concentration of thermal stress.

Incidentally, the above-mentioned triangular cracks are a specific problem that occurs in the flat panel 1, and can be said to be a phenomenon that could not occur in a curved panel. That is, the flat panel 1 has a face portion 3 having a radius of curvature of 10,000 mm or more on the outer surface on the diagonal axis X as described above.
And a skirt portion 6 extending from a peripheral edge thereof to a sealing end surface 5 which is an opening end via the blend R portion 4. Therefore, due to expansion accompanying the application of heat to the flat panel 1, structural deformation as shown in FIGS. 5 and 6 occurs. FIGS. 5A and 5B show the flat panel 1.
Is a schematic diagram of a thermal expansion deformation caused by application of heat to the flat panel 1 in one quadrant obtained by cutting the flat panel 1 along a long axis A and a short axis B (see FIG. 4). Arrows in the figure indicate the directions of deformation due to thermal expansion. FIG. 6A shows the sealing end face 5.
6A and 6B are schematic views of the periphery of the diagonal portion 7 viewed from a direction perpendicular to the face surface, in which dotted lines schematically illustrate the shape during thermal expansion deformation, and FIG. Is a schematic longitudinal sectional view of the skirt portion 6 around the diagonal portion 7 taken along the diagonal axis X, and the dotted line in the figure also schematically illustrates the shape during thermal expansion deformation.

More specifically, as shown in FIG. 5A, during the heat-up process in the heat treatment step for sealing with the funnel 2, the blending is performed from the center axis Z (tube axis) of the face portion 3. When thermal expansion occurs in the direction toward the R portion 4, that is, in the direction parallel to the outer surface of the face portion 3, one end of each side 8 of the skirt portion 6 is an open end, and therefore, FIG.
As shown in (b), the center of each side 8 in the longitudinal direction of the sealing end face, in particular, the sealing end face 5 side portion is deformed so as to fall down to the center axis Z side. When such deformation occurs,
Since the diagonal portion 7 of the skirt portion 6 cannot be freely expanded and deformed, the diagonal portion 7 of the sealing end face 5 partially protrudes to the outer surface side as shown in FIG. As shown in ()), the diagonal portion 7 is inclined upward and rises from the periphery of the face portion 3 on the diagonal portion 7 side upward.

As a result, the diagonal portions 7 of the flat panel 1
In particular, the strain due to the deformation of each side portion 8 is concentrated near the sealing end surface 5 of the diagonal portion 7, and the thermal stress value acting on the sealing end surface 5 side portion of the diagonal portion 7 is significantly increased. On the other hand, in the case of a curved panel, due to the small radius of curvature of the face portion, the face portion also undergoes thermal expansion in the direction along the central axis. Since the influence of thermal expansion on each side is reduced, the concentration of thermal stress at the diagonal portion as described above is reduced. Therefore, as the curvature radius of the outer surface of the face portion of the panel increases and becomes flat, the thermal expansion in the outer peripheral direction of the face portion due to the structure increases, and the diagonal portion 7 near the sealing end face 5 The thermal stress value generated at the time increases.

Here, the mechanism by which the above-described triangular cracks occur in the flat panel 1 will be described with reference to FIG.
In FIG. 7, solid arrows indicate stresses acting on the outer surface of the skirt 6, and dotted arrows indicate stresses acting on the inner surface of the skirt 6. Also, arrows pointing in opposite directions indicate tensile stress, and arrows pointing in an approaching direction indicate compressive stress. Furthermore, the arrow shown by the chain line shows the direction of crack propagation.

As shown in FIG. 2, in the process of raising the temperature of the flat panel 1, a predetermined position on the outer surface of the diagonal portion 7 from the sealing end face 5 to the face portion 3 due to the above-mentioned deformation due to thermal expansion. A tensile stress 1a is generated in a region (a position slightly closer to the sealing end face 5 than the mold match line 9), and thermal stress is concentrated in this region. Under such a stress generation condition, if a defect such as a minute scratch exists near the sealing end face 5 of the diagonal portion 7, a crack starts from the minute defect. Since this crack propagates in a direction substantially perpendicular to the tensile stress 1a, the crack generated near the sealing end face 5 of the diagonal portion 7 firstly has the sealing end face 5 as indicated by an arrow 2a. Perpendicular to the pipe axis (tube axis Z
In the direction parallel to the

In this case, at a portion of the diagonal portion 7 slightly closer to the sealing end face 5 than the mold match line 9,
While a compressive stress 3a is generated, a tensile stress 4a is generated on a line extending obliquely from the vicinity of this portion toward the sealing end face 5 of each side 8 on both sides thereof. For this reason, the crack that has propagated along the diagonal portion 7 along the above-mentioned arrow 2a branches and changes its direction by the tensile stress 4a with the position slightly in front of the mold match line 9 as an apex, and changes its direction from the apex to an arrow 5a. , 5a to reach the sealing end face 5. As a result, the sealing end face 5 around the diagonal portion 7
Is broken so as to peel off in a triangular pyramid shape, and the above-described triangular crack occurs.

As described above, the occurrence of damage such as triangular cracks during the heat treatment is caused by defects such as minute scratches existing at the diagonal portion 7 of the sealing end face 5 and flattened. Since this will cause fatal damage to the production of the panel 1 and, consequently, the production of a glass bulb for a cathode ray tube, this kind of problem is extremely important in view of the current situation where flat panels 1 are being produced in place of curved panels. .

The present invention has been made in view of the above circumstances, and prevents a glass panel for a cathode ray tube having a flattened face portion from being damaged due to heat treatment, such as triangular cracks, and has a high heat resistance. It is an object of the present invention to provide a high quality glass panel having excellent properties.

[0020]

SUMMARY OF THE INVENTION In order to achieve the above technical object, the present invention provides a substantially rectangular face portion forming an effective screen having a radius of curvature of an outer surface on a diagonal axis of 10,000 mm or more. A skirt portion having each side portion connected to the periphery of the face portion via a blend R portion and having a substantially rectangular sealing end surface at an open end, wherein the sealing end surface of the skirt portion is provided. Wherein a concave portion is formed at least in a region including a diagonal axis. Here, the “tube axis parallel direction” means a direction parallel to the tube axis, that is, the center axis of the panel.

According to such a configuration, the sealing end surface of the panel for the cathode ray tube is fixed to another member in a process of fixing the panel on a predetermined table when polishing the surface of the panel, or in various transporting processes of the panel. Even in the case of contact or sliding, since a recess is formed in at least the area including the diagonal axis of the sealing end face, only the area excluding the recess on the sealing end face mainly contacts or slides with the other member. And the contact or sliding between the concave portion and the other member hardly occurs. This suppresses the occurrence of minute scratches and the like at diagonal portions of the sealing end face of the panel. As a result, during the temperature rise process when sealing the panel and the funnel using frit glass,
Concentration of thermal stress on the diagonal portion of the sealing end face due to thermal expansion deformation of the panel, and occurrence of breakage such as triangular cracks due to the minute flaws and the like are suppressed beforehand.

In this case, it is preferable that the concave portion is formed only in the diagonal portion of the sealing end face and in the vicinity thereof. In this way, the thermal stress that has been concentrated on the diagonal part of the sealing end face due to the thermal expansion and deformation of the panel is transferred to the center of the sealing end face in the longitudinal direction of each side part away from the diagonal part. Since it can be reduced while being dispersed, for example, even when the size of the panel is increased, it is possible to reliably suppress the occurrence of the damage described above.

Specifically, the concave portion is formed in a range of 5 mm or more and 100 mm or less from a diagonal axis of the sealing end face toward the center in the longitudinal direction of the sealing end face of each side. Is preferred. That is, from the viewpoint of dispersing and reducing the thermal stress that has been generated concentrated on the diagonal portion of the sealing end face in the direction away from the diagonal portion as described above, and
From the viewpoint of suppressing rattling of the sealing end surface due to the formation of the concave portion, the formation region of the concave portion is at most 100 m from the diagonal axis toward the center of the longitudinal direction of the sealing end surface of each side.
m is preferable. On the other hand, the formation region of this concave portion is
When the width is less than 5 mm from the diagonal axis toward the center of the sealing end face in the longitudinal direction of each side, the thickness is increased over the entire panel by increasing the size of the panel, and the thermal expansion deformation is remarkable. In this case, the effect of forming a concave portion that is sufficient to suppress the generation of thermal stress cannot be obtained.
m or more. Here, "the center in the longitudinal direction of the sealing end face of each side" means the center in the longitudinal direction of the sealing end face for each side.

Furthermore, the recess, the tube axis parallel dimension leading to the seal end face from the mold match line of the seal end face longitudinal center of each side and h _0, the mold match line on the diagonal axis the dimensions of the tube axis direction parallel leading to the seal end face and h _1, the width of the sealing end face as S,
It is preferable to have a relationship of 0.03 ≦ (h ₀ −h ₁ ) /S≦0.17.

According to this structure, since the value of h ₀ -h ₁ , that is, the amount of depression of the concave portion is an appropriate value with respect to the width S of the sealing end surface, the panel and the funnel are sealed with frit glass. Even when a recess is formed in the diagonal part of the sealing end face, the frit glass does not have a shape defect after sealing, and the situation that the diagonal part around the sealing end face is damaged is further assured. Can be suppressed. in this case,
If (h ₀ −h ₁ ) / S> 0.17, the width S of the sealing end face
Due to the fact that the amount of depression of the concave portion with respect to the frit glass becomes excessively large, a defective shape of the frit glass occurs. In a cathode ray tube obtained by evacuating the inside of the glass bulb for a cathode ray tube obtained by the frit seal, if the above-described defective shape of the frit glass occurs after sealing, the vacuum at the diagonal portion of the sealing end surface is reduced. There is a possibility that the pressure resistance may be reduced. On the other hand, if (h ₀ −h ₁ ) / S <0.03, the amount of depression of the concave portion becomes insufficient, and there is a fear that defects such as minute scratches may occur at the diagonal portion of the sealing end surface. In addition, the effect of suppressing breakage at the time of temperature rise cannot be reliably obtained.

In addition to the above configuration, the concave portion has a gradually decreasing portion in which the amount of depression gradually decreases from the diagonal axis side of the sealing end surface toward the center in the longitudinal direction of the sealing end surface of each side. Is preferred. With such a configuration, a sudden change in the thickness does not occur despite the formation of the recess, and the amount of the recess gradually decreases to reach the non-recess-forming region of the sealing end face. The filling of the molten glass in the press mold at the time of molding is smoothly performed without being hindered, and the occurrence of molding defects such as wrinkles and cracks in the thickness change portion can be prevented.

Further, in addition to the above configuration, the concave portion may
It is preferable that the recess is formed so that the amount of depression is maximum on the diagonal axis. Here, the expression "the amount of depression is maximum on the diagonal axis" is a concept including that the amount of depression is maximum in a predetermined area including the diagonal axis. According to this structure, since the amount of dents in the portion where the occurrence of defects such as minute scratches is to be most suppressed is maximized, the occurrence of minute scratches and the like can be appropriately suppressed with high reliability, and the recesses can be efficiently reduced without waste. Can be formed, and the effect of suppressing breakage at the time of temperature rise can be further enhanced.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a glass panel for a cathode ray tube according to an embodiment of the present invention, FIG. 2 is an enlarged perspective view of a main part showing a periphery of a diagonal part of the panel, and FIG. It is a schematic plan view showing the periphery. In the following description, the same components as those described in the section of the related art described above are denoted by the same reference numerals, and the description or the detailed description thereof will be omitted.

As shown in FIG. 1, a glass panel 1 for a color cathode ray tube (hereinafter simply referred to as a panel) has a substantially rectangular face portion provided with an effective screen having a radius of curvature of the outer surface on the diagonal axis X of 10,000 mm or more. 3 and the face portion 3
And a skirt 6 having a sealing end face 5 for joining to the funnel 2 through the blend R portion 4. The skirt portion 6 has four diagonal portions 7 forming interconnecting portions of the respective side portions 8, and the sealing end surface 5
Are formed in the diagonal portions 7 (predetermined regions including the diagonal axis X). In other words, each side 8
The dimensions of the tube axis parallel extending from the mold match line 9 to the seal end face 5 at the central portion of the seal end face longitudinal (w-w direction) and h ₀ of sealing the mold match line 9 on the diagonal axis X The sealing end surface 5 is formed so as to satisfy the relationship of h ₀ / h ₁ > 1, where h ₁ is the dimension in the direction parallel to the tube axis that reaches the end surface (recess 10). In this case, preferably, assuming that the width of the sealing end face 5 is S, 0.03 ≦ (h ₀ −
h ₁ ) /S≦0.17.

As shown in FIG. 2, the concave portion 10 has a concave amount (h ₀ −) in a flat region 10a including the diagonal axis X.
h ₁ ) is maximum, and at both ends of this flat region 10a,
It has a gradually decreasing portion 10b in which the amount of depression gradually decreases from the diagonal axis X side toward the center in the longitudinal direction of the sealing end face of each side portion 8.
In this case, the gradually decreasing portion 10b is formed as a curved surface or an inclined surface that is smoothly continuous with the flat region 10a, and is connected to the non-recessed region of the sealing end face 5 at an obtuse angle. still,
Instead, the dent amount on the diagonal axis X is set to the maximum value (h
₀₋ h ₁ ), without forming a flat region and without forming a bent portion on the diagonal axis X,
May be formed symmetrically or substantially symmetrically on both sides of the side surface 8 so as to form a gradually decreasing portion formed of a curved surface or an inclined surface in which the amount of depression gradually decreases toward the center in the longitudinal direction of the sealing end face of each side portion 8.

As shown in FIG. 3, the area in which the concave portion 10 is formed has a predetermined dimension a, with respect to the diagonal axis X, toward the center in the longitudinal direction of the sealing end face of the sides 8 on both sides thereof.
b. The predetermined dimensions a and b in these two directions
Are the same size in the present embodiment, and the dimensional value is set within a range of, for example, 5 mm or more and 100 mm or less.

As a method of forming the concave portion 10 having the above-described configuration in the panel 1, there is a method of forming the concave portion 1 of the panel molding die.
0 is formed in advance at a position corresponding to 0, and when the panel 1 is press-molded, the concave portion 1 is formed.
For example, forming 0 on the panel 1 is performed. Alternatively, a method of forming the concave portion 10 by grinding, polishing, or the like after the press molding of the panel 1 is completed may be employed. For example, in a panel 1 such as a large panel that requires polishing of the sealing end face after press molding in order to remove rattling of the sealing end face due to thermal deformation of the skirt portion of the panel, the polishing amount or Depending on the grinding amount,
It is preferable to previously form a large amount of the concave portion 10.

On the other hand, the glass funnel for a cathode ray tube constituting a glass bulb for a cathode ray tube by being sealed with the above-mentioned panel 1 has a sealing end face in which a concave portion is not formed (not shown). Therefore, the glass bulb for a cathode ray tube comprises a panel 1 having a concave portion 10 formed at a diagonal portion of the sealing end surface 5 and a funnel having no such concave portion formed at the sealing end surface. It is manufactured by sealing with frit glass interposed therebetween.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can achieve a remarkable effect in comparison with the conventional example as follows.

As Embodiment 1 of the present invention, the aspect ratio is 4: 3, the outer diameter in the diagonal axis X direction is 724.8 mm, and the radius of curvature of the face outer surface on the diagonal axis X is 100,000 m.
m, a panel having a total height of 110.0 mm (dimension in the direction parallel to the tube axis from the face outer surface to the sealing end face) and a width S of the sealing end face of 11.4 mm was produced under the following conditions. . That is, with respect to the change in the amount of depression of the concave portion 10, a form having a gradually decreasing portion on both sides of the diagonal axis X without forming a flat region is adopted. extending the tube axis direction parallel dimension h ₁ 80.6mm, the size h ₀ of the tube axis direction parallel leading to the seal end face from the mold match line of the seal end face longitudinal center of each side and 82.0Mm, pairs Each of the dimensions a and b of the recess forming region extending from the square axis X toward the center in the longitudinal direction of the sealing end face of each side was set to 70 mm.

As Example 2 of the present invention, similarly, the aspect ratio was 4: 3, and the outer diameter in the diagonal axis X direction was 724.8 m.
m, the radius of curvature of the face outer surface on the diagonal axis X is 100
A panel having a thickness of 000 mm, a panel height of 110.0 mm (dimension in the direction parallel to the pipe axis from the outer surface of the face to the sealing end face), and a width S of the sealing end face of 11.4 mm was produced under the following conditions. . That is, with respect to the change in the amount of depression of the concave portion 10, a form having a flat region and a gradually decreasing portion (the form shown in FIG. 2) is adopted, and the tube axis extending from the mold match line on the diagonal axis X to the sealing end face is used. Parallel dimension h
₁ is 80.6 mm, the dimension h ₀ in the tube axis parallel direction from the mold match line to the sealing end face at the center in the longitudinal direction of the sealing end face of each side is 82.0 mm, and The dimension of each side toward the center of the sealing end face in the longitudinal direction is 40.0 mm, and the dimension of the formation area of the gradually decreasing portion from both ends of the flat area toward the center of the sealing end face in the longitudinal direction is further increased. Each was 40.0 mm.

As a conventional example, that is, as a comparative example, similarly, the aspect ratio is 4: 3, and the outer diameter in the diagonal axis X direction is 724.8 m.
m, the radius of curvature of the face outer surface on the diagonal axis X is 100
A panel having a thickness of 000 mm, a panel height of 110.0 mm (dimension in the direction parallel to the pipe axis from the outer surface of the face to the sealing end face), and a width S of the sealing end face of 11.4 mm was produced under the following conditions. . That is, the dimension h _{1 in the} direction parallel to the tube axis from the mold match line to the sealing end face without forming a concave portion.
= H ₀ was 82.0 mm over the entire circumference of the sealing end face.

The values of h ₀ , h ₁ , S and (h ₀ −h ₁ ) / S for the panels according to Examples 1 and 2 and Comparative Example are shown in Table 1 below.

[0039]

[Table 1]

For each of the panels according to Examples 1 and 2 and Comparative Example, a predetermined polishing step was performed after molding, and the outer surface of the face portion was mirror-polished. The polishing was performed by placing a panel on a predetermined table such that the table surface and the sealing end surface were in contact with each other. After the completion of the polishing step, each panel was immersed in a 20% hydrofluoric acid aqueous solution for 30 seconds to emphasize the micro flaws generated on the sealing end face, and the state was visually observed. The reason for such observation is that when the glass is immersed in a concentrated hydrofluoric acid aqueous solution, invisible microscopic scratches and irregularities existing on the glass are emphasized by the glass erosion effect of hydrofluoric acid,
This is because visual recognition becomes possible.

According to the results of the experiment, in the panels of Examples 1 and 2, there were hardly any micro scratches that could be caused by the above-mentioned polishing work in the concave portions 10 on the sealing end faces. Therefore, it was confirmed that the panels of Examples 1 and 2 can suppress the generation of micro scratches at the diagonal portion of the sealing end face and in the vicinity thereof. On the other hand, in the panel according to the comparative example, generation of a large number of micro flaws was confirmed at the diagonal portion of the sealing end face and in the vicinity thereof.

Next, corresponding to the panels according to the first and second embodiments and the comparative example, the aspect ratio is 4: 3, the outer diameter in the diagonal axis direction is 724 mm, and the width S of the sealing end face is 11.4 mm.
Was manufactured (deflection angle: 120 °). Then, these funnels are set on a predetermined jig, and a slurry obtained by dispersing frit glass (manufactured by Asahi Glass Co., Ltd .; ASF-1307B) in an organic vehicle is applied onto the sealing end face of the funnel. After drying, the corresponding panel was placed on the sealing end face.
Thereafter, these were passed through a heat treatment furnace having a predetermined temperature gradient maintained at a maximum temperature of 450 ° C. for 20 minutes, and the frit glass was reacted with the sealing end face of the panel and the funnel, thereby obtaining Examples 1 and 2. A glass bulb for a cathode ray tube obtained by sealing each panel and each funnel according to Comparative Example 2 and Comparative Example was obtained.

In this case, as a result of executing the process of sealing the frit glass through a heat treatment furnace for each of ten glass bulbs corresponding to the first and second embodiments and the comparative example, the one corresponding to the first and second embodiments was obtained. In each case, triangular cracks due to thermal tensile stress did not occur, but in the case of Comparative Example, the occurrence of triangular cracks or breakage similar thereto was observed. Further, as a result of examining the pressure resistance of each of the glass bulbs corresponding to Examples 1 to 3, it was found that each of the bulbs had a pressure resistance of 3.
5 kg / cm ² or more sufficiently large, even when the evacuated interior of the glass bulb for a cathode ray tube in a high vacuum, the recess 1
It was confirmed that the formation of 0 did not adversely affect the mechanical strength of the glass bulb.

[0044]

As described above, according to the present invention, in a cathode ray tube panel having a substantially rectangular face portion forming an effective screen having a radius of curvature of the outer surface on the diagonal axis of not less than 10,000 mm, a skirt portion is provided. Since the concave portion is formed at least in the region including the diagonal axis on the sealing end surface of the sealing end surface, even if the sealing end surface and other members come into contact with or slide in various steps after molding of the panel, the sealing is performed. The contact or sliding of the diagonal portion of the end surface can be avoided. As a result, the occurrence of minute scratches or the like at the diagonal portion of the sealing end face of the panel is suppressed, and triangular cracks or the like starting from the small scratches at the diagonal outside of the sealing end face during expansion deformation due to heat treatment of the panel. It is possible to suppress the problem of the occurrence of breakage beforehand.

The recess is formed in a range of 5 mm or more and 100 mm or less from the diagonal axis of the sealing end face toward the center of the side of the sealing end face in the longitudinal direction of each side, so that minute scratches and the like can be prevented. The effect of suppressing the generation can be sufficiently obtained, and the thermal stress from the diagonal portion can be appropriately dispersed and reduced.

In addition, the concave portion has a value of 0.03 ≦ (h ₀ −
By having a relationship of h ₁ ) /S≦0.17, even if a concave portion is formed at a diagonal portion of the sealing end surface, a defective shape of the frit glass does not occur after sealing with the funnel, and the sealing end surface does not occur. Can be more reliably suppressed from being generated around the diagonal portion of the above.

Further, the recess is formed by providing a gradually decreasing portion in which the amount of the recess gradually decreases from the diagonal axis side of the sealing end face toward the center in the longitudinal direction of the sealing end face of each side. Despite this, no sudden change in wall thickness occurs, and the amount of dent gradually decreases to reach the non-recessed area of the sealing end face. Filling can be performed smoothly, and occurrence of molding defects such as wrinkles and cracks in the thickness change portion can be prevented.

Further, since the amount of depression of the concave portion is maximized on the diagonal axis, the occurrence of minute scratches and the like is appropriately suppressed with high reliability, and the effect of suppressing damage during temperature rise is further enhanced. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a glass panel for a cathode ray tube according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a main part of a glass panel for a cathode ray tube according to an embodiment of the present invention.

FIG. 3 is a schematic plan view showing a main part of a glass panel for a cathode ray tube according to an embodiment of the present invention.

FIG. 4 is a perspective view showing a conventional glass panel for a cathode ray tube.

FIGS. 5A and 5B are schematic perspective views schematically showing a glass panel for a cathode ray tube showing a conventional problem.

FIG. 6A is a schematic plan view of a main part of a glass panel for a cathode ray tube showing a conventional problem, and FIG. 6B is a schematic longitudinal section of a main part of a glass panel for a cathode ray tube showing a conventional problem. It is a front view.

FIG. 7 is an enlarged schematic front view of a main part of a glass panel for a cathode ray tube showing a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Panel (glass panel for cathode ray tubes) 3 Face part 4 Blend R part 5 Sealing end face 6 Skirt part 7 Diagonal part 8 Side part 9 Mold match line 10 Concave part 10b Decreasing part X Diagonal axis

Claims (5)

[Claims] 1. An outer surface having a radius of curvature of 1 on a diagonal axis.
A substantially rectangular face portion forming an effective screen of 0000 mm or more, and a skirt portion having peripheral sides connected to the periphery of the face portion via a blend R portion and having a substantially rectangular sealing end surface at an open end; A cathode ray tube panel comprising: a glass panel for a cathode ray tube, wherein a concave portion is formed in a region including at least a diagonal axis on a sealing end surface of the skirt portion. 2. The method according to claim 1, wherein the recess is formed in a range from 5 mm to 100 mm from a diagonal axis of the sealing end face toward a center in a longitudinal direction of the sealing end face of each side. The glass panel for a cathode ray tube according to claim 1. Wherein the recess, the dimensions of the tube axis direction parallel leading to the seal end face from the mold match line of the seal end face longitudinal center of each side and h _0, mold match on the diagonal axis A relationship of 0.03 ≦ (h ₀ −h ₁ ) /S≦0.17, where h ₁ is the dimension in the pipe axis parallel direction from the line to the sealing end face, and S is the width of the sealing end face. The glass panel for a cathode ray tube according to claim 1 or 2, wherein: 4. The concave portion includes a gradually decreasing portion in which the amount of depression gradually decreases from a diagonal axis side of the sealing end surface toward a central portion in a longitudinal direction of each side of the sealing end surface. The glass panel for a cathode ray tube according to claim 1. 5. The recess according to claim 1, wherein the recess is formed so as to have a maximum recess on a diagonal axis.
5. The glass panel for a cathode ray tube according to any one of 4.