JPH11339692A - Panel glass for implosion-proof cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress implosion of a cathode-ray tube and to enhance its stable strength. SOLUTION: In this panel glass, a compression stress of 7-30 MPa is applied to at least the outer surface of a face part 7, and the radius of curvature Rb of the outer surface of a blend R part 9 in the diagonal part of the panel glass is set at a value satisfying Rb >=0.017D+4.0, to the maximum outer diameter D of the panel glass. Also, when the face part is flat, the maximum thickness Tr of the blend R part is set at a value satisfying Tr <=0.014D+11.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a panel glass for a cathode ray tube mainly used for television broadcast reception and industrial equipment.

[0002]

2. Description of the Related Art As shown in FIG. 3, a cathode ray tube 1 basically comprises a panel glass 3 for displaying an image, a funnel 4 for mounting a deflection coil, and a neck 5 for accommodating an electron gun 17. It is composed of a valve 2.

In FIG. 3, reference numeral 6 denotes a panel skirt, 7
Is a face portion for displaying an image, 8 is a reinforcing band for maintaining strength against impact, 9 is a blend R portion connecting the face portion and the skirt portion, 10 is a panel glass 3 and a funnel portion 4 are sealed with solder glass or the like. 12 is a fluorescent film that emits fluorescence when irradiated with an electron beam, 13 is an aluminum film that reflects the light emitted from the fluorescent film forward, 14 is a shadow mask that specifies the position of the electron beam irradiation on the phosphor, 15
Is a stud pin for fixing the shadow mask 14 to the inner surface of the panel skirt portion 6, and 16 is a shadow mask 14
This is an interior tag for preventing high charge potential due to the electron beam and for conducting and grounding to the outside. A is a tube axis connecting the center axis of the neck portion 5 and the center of the panel glass 3. The screen in which the fluorescent film 12 is formed on the inner surface of the panel glass has a four-axis structure which is substantially parallel to the major axis and the minor axis which are centered on the tube axis A and are orthogonal to the tube axis A.
It is almost rectangular with sides.

[0004] Since the cathode ray tube displays an image by irradiating an electron beam inside the panel glass, the inside is kept at a high vacuum. Then, since an internal / external pressure difference of 1 atm is applied to an asymmetric structure different from the spherical shell, a high deformation energy is contained therein and the state is unstable. If a crack occurs in the cathode ray tube panel glass in such a state, the internal high deformation energy is not released,
The cracks grow rapidly, leading to large-scale fractures such that the cracks propagate throughout the panel glass.

[0005] Above all, when the growth rate of a crack is high, such as when it is broken by a mechanical impact, the panel glass is broken instantaneously, and an explosive shrinkage phenomenon and its reaction cause
This causes an implosion phenomenon that scatters a large amount of sharp glass fragments. Usually, in order to protect the user from the implosion phenomenon, the reinforcing band 8 is attached to the side surface of the panel glass 3 to suppress the extension of the crack and the breakage of the tube. In recent years, the face portion of the panel glass has tended to be flattened in order to improve the visibility of the cathode ray tube, but this has also tended to increase the asymmetry in structure of the cathode ray tube, and the implosion phenomenon is more likely to occur.

[0006]

In such a panel glass for a cathode ray tube, the face diagonal portion having high structural rigidity has a sharp change with time in the stress generated in the impact portion and its vicinity due to mechanical impact. And large, the probability of crack generation is high, and the crack growth speed is likely to be high, and the implosion phenomenon is more likely to occur. Therefore, even if it has sufficient strength against the impact of other parts, the thickness of the face part is reduced only to prevent the implosion phenomenon that occurs when an impact is applied to this part. Increase
In some cases, it is necessary to reduce the generated stress. However, in this case, the weight which is the biggest disadvantage of the cathode ray tube is increased.

[0007] It is an object of the present invention to provide a safe panel glass having a high implosion prevention effect by selectively reducing the rigidity of the face diagonal to reduce the stress generated by mechanical impact.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is a panel glass having a substantially rectangular face portion and a skirt portion forming a side wall thereof. The compressive stress σ _c due to physical strengthening is formed on the outer surface of the portion in the range of 7 MPa ≦ | σ _c | ≦ 30 MPa, and the blend R portion connecting the face portion and the skirt portion at the diagonal portion of the face portion. Provided is a panel glass for an explosion-proof cathode ray tube, wherein the outer surface has a curvature radius _Rb with respect to the outermost diameter D of the panel glass, _Rb ≧ 0.017D + 4.0. further,
The face portion is substantially flat, and the maximum thickness _Tr of the blend R portion at the diagonal portion of the face portion is _Tr ≦ 0.014D + 11.0 with respect to the outermost diameter D of the panel. The above-mentioned panel glass for an explosion-proof cathode ray tube is provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention specifies the shape and thickness of the area of the connecting portion between the face portion and the skirt portion at the diagonal portion of the panel glass having a substantially rectangular face portion. Selectively lowers the structural rigidity of the face diagonal, reduces the stress generated when subjected to a mechanical shock while maintaining the function as a vacuum vessel, and suppresses the occurrence of cracks and the extension The effect is obtained.

In a normal cathode ray tube, a stress generated in a portion subjected to impact by a mechanical impact and in the vicinity thereof is as follows.
If the rigidity of the portion is high, the maximum value becomes large, and the time for generating stress becomes short. Conversely, when the rigidity is low, the maximum value tends to be small and the generation time tends to be long. Also, the higher the generated stress, the higher the probability of crack generation. On the other hand, the shorter the stress generation time, the more easily the deformation energy due to the impact is concentrated in the vicinity of the impact part. In this case as well, not only the probability of crack generation but also the crack growth speed is increased, and the amount of crack growth is also increased. Increase.

From the viewpoint of preventing the implosion phenomenon, it is desirable that the structural part of the impact receiving part has low structural rigidity as long as the structure can be maintained as a vacuum vessel. In a panel glass for a cathode ray tube, a portion that may receive a mechanical shock during use is a face portion exposed from a television device or the like. The structurally most rigid portion of the face portion is a diagonal portion of the face portion (face diagonal portion) to which the three surfaces of the substantially box-shaped panel glass are joined. The area where the implosion phenomenon is most likely to occur is the face diagonal.

In order to suppress the implosion phenomenon that occurs when an impact is applied to the diagonal face, it is necessary to reduce the rigidity of the diagonal face. The effect is large and the degree of freedom of the shape is small. The face portion is the flattest and widest area in the shape of the panel glass, and changing the shape and thickness of the face portion affects the rigidity of the entire panel glass.

According to the present invention, the shape of the blend R portion at the diagonal portion of the panel glass (hereinafter, simply referred to as the blend R portion) is closely related to the decrease in rigidity of the face diagonal portion. By changing the shape of the blend R portion, the rigidity of the face diagonal where the implosion phenomenon is most likely to occur is selectively changed without affecting the image quality, and this is changed. It lowers.

Next, the present invention will be described in detail with reference to FIGS. 2 is a plan view of the panel glass 3, and FIG. 1 is a partial cross-sectional view of a diagonal portion of the panel glass 3, and is a cross-sectional view taken along a line BB of FIG. In FIG. 1, _Rb indicates the radius of curvature of the outer surface of the blended R portion 9, and _Tr indicates the maximum thickness of the blended R portion 9. If the radius of curvature _Rb of the blend R portion 9 is not uniform, the maximum radius of curvature is used. In addition, the face diagonal part where the possibility of the implosion phenomenon is high is located near the corner of the face part 7, and FIG. 2C shows this part for convenience.

The function of the blend R portion 9 is to support the face portion 7 against the mechanical impact of the face diagonal portion C. By increasing the _{Rb of the} blend R portion, The blend R portion 9 is made to have a soft structure, and the blend R portion 9 has a function of releasing the impact received by the face diagonal portion C. Specifically, the curvature radius R _b of the outer surface of the blend R portion 9, with respect to the outermost diameter D of the panel glass 3, R _b
≧ 0.017D + 4.0.

When R _b <0.017D + 4.0, the effect of lowering the rigidity of the face diagonal C is weakened, and the probability of implosion is increased. Here, the outermost diameter D is the maximum dimension between the outer surfaces of the skirt portion 6 in the diagonal axis direction of the panel glass 3 as shown in FIG. Although the radius of curvature _Rb of the outer surface of the blend R portion 9 is substantially constant in the range between the face portion and the skirt portion, if it is different in the range, it can be determined as the average radius of curvature.

Further, since the present invention is based on the premise that the image quality of the cathode ray tube is not affected, the upper limit of the above-mentioned _Rb is substantially limited to the effective screen area where the blend R portion becomes the screen surface of the face portion 7. Decide to be on the outside. Therefore, it is desirable that even if _Rb increases and the blend R portion expands, it does not reach the screen plane. Also,
When the R _b is increased unnecessarily, if fitted with the outer periphery to the reinforcing band 8 of the skirt portion 6 of the panel glass 3, because it may inhibit the tightening effect of the reinforcing band in the diagonal section, in determining the R _b It is important to consider this point.

Furthermore, by applying a compressive stress to the surface of the panel glass by physical strengthening, the generation of cracks can be further suppressed. This is because the tensile stress generated by the mechanical impact on the face surface is apparently reduced due to the superposition of the compressive stress existing due to the physical strengthening. Specifically, at least the compressive stress σ
_c is formed in the range of 7 MPa ≦ | σ _c | ≦ 30 MPa.
When | σ _c | <7 MPa, a sufficient effect cannot be obtained, and 30M
In the case of Pa <| σ _c |, when a crack occurs, the self-propelling property of the crack appears due to the action of releasing the residual strain energy stored inside by the physical strengthening, the amount of crack extension increases, and the purpose of suppressing the implosion phenomenon Not practical. Therefore, it is important to physically strengthen the outer surface of the panel within the range of the stress value in order to achieve the object of the present invention.

However, since the compressive stress on the outer surface of the face is formed by physically strengthening the panel glass, the compressive stress is generally simultaneously formed on the inner surface of the face and the skirt. In the present invention, forming a compressive stress at least on the outer surface of the face portion refers to such a state. In this case, although the magnitude of the compressive stress of the portion other than the outer surface of the face portion is not specified,
Usually smaller than the outer surface of the face.

The compressive stress is measured by cutting out a test piece of a desired size from an arbitrary portion of the face portion, and measuring the compressive stress on the surface of the test piece using a photoelastic stress meter according to JIS-S2305 direct method (Senamont method). I do.

In a cathode ray tube having a substantially flat face portion which enhances the visibility of the cathode ray tube, if a crack occurs, the glass pieces separated by the crack have a curved face surface. The implosion phenomenon is more likely to occur. This is because a cathode ray tube having a substantially flat face portion has a strong asymmetry in structure, and increases the uneven distribution of deformation energy. In addition, even when a face part having a curvature is cracked and the glass piece is separated from the structure, its cross section becomes wedge-shaped and the glass pieces hold each other, whereas a substantially flat face part is used. Since the cross section of a glass piece becomes rectangular and the glass piece is easily separated, there is a high possibility that an implosion phenomenon occurs.

Therefore, in order to suppress the occurrence of implosion of a cathode ray tube having a substantially flat face portion as described above, it is important to further reduce the probability of occurrence of cracks. Stiffness needs to be further reduced. Generally, the shape and thickness are effective as factors for determining the rigidity of a certain portion on the panel glass. In the case of a cathode ray tube having a face portion having a curvature, it is possible to considerably achieve the object by increasing the radius of curvature _Rb outside the blend R portion as described above, but the face portion is substantially flat, that is, the curvature radius of the face portion. In the case of a cathode ray tube having a large R, the thickness of the blend R portion is controlled in addition to the aforementioned radius of curvature _Rb in order to further reduce the rigidity of the blend R portion, that is, the rigidity of the face diagonal portion.

Specifically, the maximum thickness _Tr of the blend R portion is
However, with respect to the outermost diameter D of the panel, _Tr ≦ 0.014D +
By satisfying 11.0, low rigidity of the blend R portion is realized. By improving the blend R portion to have a flexible structure by thinning, the stress concentration is reduced or prevented. When T _r > 0.014D + 11.0, the effect is reduced and the probability of the occurrence of an implosion phenomenon is increased. It goes without saying that the thickness of the blend R portion is a thickness that guarantees the necessary strength as a cathode ray tube bulb.

In the above description, the blend R portion other than the diagonal portion of the panel glass is not particularly mentioned. However, this is because the face diagonal portion is extremely important for the explosion-proof measures of the cathode ray tube. As described above, the optimization of the shape and thickness of the blend R portion of the diagonal portion close to the face diagonal portion is based on the fact that it is particularly effective in suppressing the implosion phenomenon of the panel glass. Therefore, the shape and thickness of the blend R portion other than the diagonal portion of the panel glass are not required to be as strict as the diagonal portion, and may be appropriately determined in the same manner as in the related art.

[0025]

(Example 1) The panel glass used in this example is one commonly used for a cathode ray tube as shown in FIG. 3, and all of them are made of Asahi Glass.

The panel glass has an aspect ratio of 4:
3. Panel glass for 29-inch television (deflection angle: 108 °) having an effective screen with a diagonal diameter of 68 cm. The radius of curvature _Rb of the outer surface of the blend R portion at the diagonal portion is 16.5 mm, the conventional product (Comparative Example 1) in which _Rb is 12.7 mm and the face portion is a curved surface, and the blend R of the diagonal portion are It has the same shape except for the part. By physically strengthening each panel glass, a compressive stress of 25 MPa was applied to at least the outer surface of the face portion. Table 1 shows the approximate dimensions and the implosion rate of Example 1 and Comparative Example 1 of the present invention.

When the radius _Rb of the outer surface of the blend R portion at the diagonal portion was changed from 12.7 mm (Comparative Example 1) to 16.5 mm, the incidence of implosion decreased from 5% to 0%. Also, there is substantially no change in weight. The evaluation method at this time was a method specified in IEC65, and a method of impacting with a steel ball having a diameter of 40 mm at an energy of 5.5 J was employed. The impact position is 20 mm in the short axis direction and 20 mm in the long axis direction from the diagonal end of the face (accurately, the screen).
The point inside mm was the point where the implosion phenomenon was most likely to occur within the range defined by the IEC65.

[0028]

[Table 1]

(Embodiment 2) The panel glass of this embodiment is
It was manufactured using the same glass material as in Example 1. The panel glass has a substantially flat face portion, an aspect ratio of 16: 9, and a diagonal diameter of 66 cm for use with a 28-inch television having an effective diameter (deflection angle: 102 °). _Have the same shape except for the radius of curvature _Rb and the maximum thickness _Tr of the blend R portion at the diagonal portion thereof. Comparative Example 3 is the same as Comparative Example 3 except for the difference of whether or not it is physically reinforced. The approximate dimensions and implosion incidence are shown in Table 2 together with Comparative Examples 2 and 3.

The panel glass of Example 2 was changed to 20mm the curvature radius R _b of 8mm of Comparative Example 2, was adjusted Blends R portion surface, compare the maximum thickness T _r of the blend R portion EXAMPLE 2 From 23.4 mm to 20.8 mm.
As a result of applying a compressive stress of 25 MPa to at least the outer surface of the face portion by physically strengthening this panel glass, the incidence of implosion decreased from 40% to 0% as compared with Comparative Example 2 which was not physically strengthened. did. Also, the compression stress due to the physical strengthening was reduced from 5% to 0% as compared with Comparative Example 3 in which at least the face outer surface was not applied. The evaluation method was the same as in Example 1.

[0031]

[Table 2]

[0032]

According to the present invention, the rigidity of the face diagonal portion is reduced by a very simple method that combines the physical strengthening of the panel glass and the adjustment of the shape of the blended R portion at the diagonal portion, thereby reducing the use of the cathode ray tube. It has an excellent effect of suppressing the occurrence of the most dangerous phenomenon, the implosion phenomenon, and realizing a safe panel glass. In particular, in order to improve visibility, the frequency of the implosion phenomenon is usually increased in a cathode ray tube having a substantially flat face surface, but due to the effect of the present invention, the implosion phenomenon is not impaired without impairing the visibility. In addition to being able to suppress weight loss for the purpose of suppressing the implosion phenomenon,
A lightweight and safe panel glass for a cathode ray tube can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a diagonal portion (a BB portion in FIG. 2) of a panel glass showing an outline of the present invention.

FIG. 2 is a plan view of a panel glass according to an embodiment of the present invention.

FIG. 3 is an explanatory view in which a part of a cathode ray tube is cut away.

[Explanation of symbols]

 1: cathode ray tube 3: panel glass 6: skirt 7: face 9: blend R

Claims (4)

[Claims] 1. A panel glass having a substantially rectangular face portion and a skirt portion forming a side wall thereof, wherein at least an outer surface of the face portion has a compressive stress σ due to physical strengthening.
_c is formed in the range of 7 MPa ≦ | σ _c | ≦ 30 MPa, and the radius of curvature R of the outer surface of the blend R portion connecting the face portion and the skirt portion at the diagonal portion of the face portion
_b is R _b ≧ 0.01 with respect to the outermost diameter D of the panel glass.
A panel glass for an explosion-proof cathode ray tube, which is 7D + 4.0. 2. A panel glass having a substantially rectangular face portion and a skirt portion forming a side wall thereof, wherein at least the outer surface of the face portion has a compressive stress σ _c by physically strengthening the panel glass. Is 7MPa ≦
| Σ _c | ≦ 30 MPa, and at the diagonal portion of the face portion, the curvature radius R _b of the outer surface of the blend R portion connecting the face portion and the skirt portion is the outermost diameter D of the panel glass. , R _b ≧ 0.017D + 4.
A panel glass for an explosion-proof cathode ray tube, which is 0. 3. The face portion is substantially flat, and the maximum thickness _Tr of the blend R portion at a diagonal portion of the face portion is equal to the outermost diameter D of the panel: _Tr ≦ 0.014D + 11.
3. The panel glass for an explosion-proof cathode ray tube according to claim 1, wherein the value is 0. 4. An explosion-proof cathode ray tube using the panel glass according to claim 1, 2 or 3.