JP2002343273A - Glass bulb for cathode-ray tube and cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the breakage in a heating process, of a glass bulb for a cathode-ray tube, provided with a panel part which is thick in distribution of the thickness of the face part. SOLUTION: This glass bulb satisfies TL/TC>=1.7, TS/TL=0.43-0.50, and TF/TC=0.37-0.49, where TC is the thickness of a center of the face part 4 of the panel part 1; TL is the thickness of an edge of the effective image plane; TS is the width of the sealed end face of a skirt part; and TF is the thickness of an intermediate part of a body part 7 of a funnel part 2; and 5-14 MPa reinforced compression stress is applied to the outer face of the skirt part.

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 and a cathode ray tube using a panel portion having a substantially flat outer surface and a large thickness distribution on the face portion.

[0002]

2. Description of the Related Art A cathode ray tube comprises a glass bulb comprising a funnel-shaped funnel having a panel for displaying images and a neck for accommodating an electron gun at one end. The panel part is substantially box-shaped and a screen (screen part)
Are formed, and a skirt portion extending substantially perpendicularly to the periphery of the face portion and forming a side wall.

[0003] In recent years, as the panel portion, a face portion whose outer surface is substantially flat, whose inner surface has a concave curved surface, and whose strength is improved by physical strengthening has been used.
Generally, in the case of a cathode ray tube panel using a shadow mask, when the electron beam from the electron gun mounted on the neck is controlled by the shadow mask and projected on the fluorescent screen inside the face, the shadow mask is used. In order to make the control of the panel easier or to improve the strength for the purpose of improving the explosion-proof characteristics of the cathode ray tube, the periphery of the face portion of the panel portion is significantly thicker than the center portion. That is, the face portion of the panel portion has a thickness distribution such that the thickness increases from the center to the periphery. For example, in Japanese Patent Application Laid-Open No. 11-67124, the peripheral thickness is set to be 1.5 times or more the central thickness.

[0004]

However, when such a panel portion is joined to the funnel portion via the end surface of the skirt portion by frit glass, and further subjected to a heat treatment step (exhaust step), a face line is produced. Since a large thermal stress is generated due to the thickness distribution of the portion, breakage occurs and productivity is deteriorated.

That is, in the panel portion having a large thickness distribution of the face portion as described above, a large thermal stress is applied from the edge of the face portion to the blend portion and the skirt portion in the heat treatment process due to a difference in thickness between the center and the periphery of the face portion. appear. In the case of a panel portion having no or small thickness distribution between the center and the periphery of the face portion, this thermal stress is not so problematic. For example, when the effective screen diagonal diameter is 60 cm and the peripheral portion thickness of the face portion is small. In the case of a cathode ray tube exceeding 1.7 times the thickness of the central portion, the thermal stress generated in the panel reaches 30 to 40 MPa. Glass increases the probability of exponential failure in this range of stress values. For this reason,
A slight increase in thermal stress leads to a significant increase in breakage, which has a large effect on productivity.

In order to reduce the thermal stress, it is most effective to reduce the thickness distribution of the face portion. However, since the shape of the inner and outer surfaces of the face portion is an important portion related to image quality and visibility. Not easily changeable.

Further, in order to suppress breakage of the glass bulb,
There is a method of strengthening the panel portion by, for example, physical strengthening.
In this method, the thermal stress is offset by leaving the compressive stress due to the physical strengthening, and the crack is suppressed. In the case of a panel with a large wall thickness distribution in the face, it is difficult to apply a uniform reinforcing stress because the cooling of the face and the skirt tends to be different when the glass cools and solidifies during the glass molding process. Becomes For this reason, not only the sufficient effect of suppressing the breakage of the glass bulb cannot be obtained, but also unexpected breakage may occur due to the unnecessary tensile stress.

Further, the design of the panel portion and the funnel portion has not been sufficiently considered to suppress the thermal stress. For example, a cathode ray tube is manufactured by combining a funnel portion with a physically reinforced panel portion. Sometimes, the thermal stress cannot be sufficiently suppressed. Furthermore, optimization has not been achieved in terms of reducing the weight of the glass bulb.

On the other hand, if the funnel portion is too thin, the imbalance of the heat capacity with the panel portion increases, so that in the heat treatment step, too much heat is applied too quickly or too fast to generate excessive thermal stress, and at the same time, the funnel portion is excessively heated. However, since the strength is also decreased, the actual situation is that a sufficient weight reduction is not usually achieved in order to make the thickness thicker to compensate for this decrease.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to minimize the thermal stress in a panel portion having a large thickness distribution in a face portion, effectively impart physical strengthening, and provide a lightweight glass bulb and a lightweight glass bulb. And a cathode ray tube using the same.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and as a result of examining thermal stress generated in a panel portion having a large wall thickness distribution in a face portion in a heat treatment step, it has been found that the skirt portion has a large thickness. When the thickness is harmonized with the thickness of the periphery of the face portion, it is found that the effect of suppressing the thermal stress can be obtained, and the outer surface region of a portion connected to the skirt portion from the short axis end or the long axis end of the face portion. It has been found that by applying a desired reinforcing compressive stress, thermal stress can be effectively canceled to prevent breakage.

Further, the present invention relates to the relationship between the thermal stress generated in the panel portion in the heat treatment step and the stress generated by evacuating the inside of the valve (hereinafter referred to as "vacuum stress") and the thickness of the funnel portion. As a result of the study, the thickness of the funnel part is closely related to these thermal stress and vacuum stress.If the thickness of the funnel part is within a predetermined range with respect to the thickness of the face part, the thickness can be reduced while manufacturing. Found that damage can be prevented by suppressing thermal stress in the process,
This completes a lightweight glass bulb.

That is, according to the present invention, there is provided a panel portion having a rectangular face portion having a substantially flat outer surface and a concave curved inner surface, and a skirt portion extending substantially perpendicular to the periphery of the face portion. A glass bulb for a cathode ray tube, comprising a funnel portion having one end connected to the panel portion and a neck portion connected to the other end portion of the funnel portion, wherein at least the panel portion is given a compressive stress by physical strengthening. Wherein the panel portion has a thicker effective screen end of the effective screen end portion on the short axis and the effective screen end portion on the long axis of the face portion. Assuming that the center thickness is T _C and the thickness of the effective screen edge is T _L , 1.70 ≦ T _L / T _C , and 2) the reinforcing compressive stress value σ _C at least near the mold match on the side surface of the skirt portion is , 5MPa ≦ | _C | ≦
3) When the thickness of the sealing end face of the skirt portion is T _S , 0.43 ≦ T _S / T _L ≦ 0.50, and the funnel portion is: 4) Sealing of the funnel portion When the length in the tube axis direction of the body portion formed between the end portion and the yoke portion is B, the thickness _{TF at} the position of B / 2 is 0.37 ≦ _TF / T.
Provided is a glass bulb for a cathode ray tube, which satisfies the conditions of 1, 2, 3, and 4, that is, _C ≦ 0.49. Further, the present invention provides a cathode ray tube manufactured using the glass bulb having the panel part and the funnel part.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the present invention reduces the cooling difference between the face and the skirt by specifying the shape of the skirt of the panel where the thickness distribution of the face is large. By controlling the imbalance of the compressive stress, the effect of the physical strengthening is sufficiently obtained.
That is, by specifying the thickness of the skirt and the compressive stress value by physical strengthening, the thermal stress generated due to the thickness distribution of the face is suppressed, and the damage to the panel is prevented or reduced. And

In the present invention, the thickness of the skirt portion and the value of the compressive stress due to the physical strengthening are specified on the short axis or the long axis of the face portion for convenience. This is because breakage is likely to occur from this part. The reason is that the effective screen end is the thickest due to the thickness distribution of the face part. Under the influence of the wall thickness distribution, a large thermal stress is generated particularly in the short axis or the long axis, and the tensile vacuum stress is also maximized in the center of the side of the face. When the short axis and the long axis are compared, the thermal stress is higher at the end of the effective screen where the thickness is larger.

Therefore, according to the present invention, the thickness and the physical enhancement of the skirt portion at the thicker effective screen end of the effective screen end on the short axis and the effective screen end on the long axis. It is important to specify the compressive stress value due to.
The thickness of the effective screen edge at the short axis or the long axis is determined by the design value of the aspect ratio of the effective screen and the inner shape of the face, so it is not uniform whether the wall thickness is large. It depends on the type. If the required thickness and compressive stress value due to physical strengthening can be specified for the selected short axis or long axis, the other parts are the same because damage in the heat treatment process is less likely to occur than the short axis or long axis. Or, it may be designed based on this specific requirement. This concept is the same for the funnel.

Next, the present invention will be specifically described with reference to the drawings. FIG. 1 is a partial sectional view of a glass bulb according to the present invention, FIG. 2 is a plan view of a panel portion, and FIG. 1 is a sectional view of an AA portion in FIG. Therefore, FIG. 1 shows a cross section of the right half of the short axis of the glass bulb. In FIG.
X and Y indicate the major axis and the minor axis of the face unit 4, respectively, and the virtual line 9 indicates the effective screen of the face unit 4. In the glass bulb of this example, the wall thickness of the effective screen end in the short axis of the face portion 4 is larger than the wall thickness of the effective screen end in the long axis.
It suffices to specify the constituent elements of the present invention in the panel portion and the funnel portion with respect to the short axis. Hereinafter, this requirement will be described in detail.

As is clear from FIG. 1, the glass bulb comprises a panel portion 1 and a funnel portion 2 having a neck portion 3 at an end. The panel portion 1 is formed by a face portion 4 having a substantially flat outer surface and a concave curved inner surface, and a skirt portion 6 extending substantially perpendicular to the periphery of the face portion. Thereby, it is a hollow box as a whole, and has a blend portion 5 at a curved corner where the face portion 4 and the skirt portion 6 are connected. The above-mentioned “outer surface is substantially flat” means that the outer surface has a minimum radius of curvature of 250.
It means that it is 00 mm or more.

The funnel portion 2 is connected to the funnel-shaped body portion 7, a yoke portion 8 having a circular or substantially rectangular cross section perpendicular to the tube axis Z, and sealed with the yoke portion. The end of the body 7 has a substantially rectangular sealing end to be joined to the end of the skirt of the panel 1 by, for example, frit glass. Therefore, the shape and thickness of the end portion of the body portion 7 are substantially the same as those of the end surface of the skirt portion of the panel portion 1, and the thickness of the end surface is also the same over the entire circumference.

The face part 4 of the panel part 1 is
It has a thickness distribution depending on the shape of the outer surface,
There is a large wall thickness distribution between the center and the periphery. That is,
The center thickness of the face part is T_C, The thickness of the effective screen end 9
T_L1.70 ≦ T _L/ T_CIt has become. This
This identifies panels where the face thickness distribution is particularly large
are doing. Where T_LIs flat on the tube axis Z of the effective screen end 9.
It is the thickness in the line direction. T_L/ T_CIs less than 1.70
The skirt has a relatively small thickness distribution.
Even without specifying the thickness or compressive stress value due to physical strengthening,
No damage is caused by force. Note that T_L/ T_CSpecific upper limit
No, but it is limited by the cathode ray tube design specifications
Usually, it is about 2.50.

Next, the compressive stress applied to the panel section 1 by physical strengthening will be described. The panel portion 1 is physically reinforced by a conventionally known method, and the face portion 4,
Compressive stress is applied to at least the outer surfaces of the blend portion 5 and the skirt portion 6. Since this compressive stress acts to offset thermal stress and vacuum stress generated in the panel portion, it is extremely effective in preventing breakage due to these stresses. It is known that the magnitude of the applied compressive stress varies depending on the location of the panel portion.

The present invention is based on the fact that the compressive stress applied to the vicinity of the mold match 12 of the skirt portion 6 is particularly effective for preventing breakage in the heat treatment step. The mold match 12 is formed by a molding die and is usually located on the outer surface of the skirt portion 6 adjacent to the blend portion 5. The vicinity of the mold match refers to the vicinity of the mold match of the blend portion 5 and the upper portion of the skirt portion 6. Since the vicinity of the mold match is thicker together with the blend portion 5, the outer surface of the panel portion receives a large tensile thermal stress during cooling in the heat treatment step.

Furthermore, since the funnel has a smaller heat capacity than the panel, the funnel cools faster than the panel during cooling, so that the heat shrinks more than the panel. This heat shrinks the skirt of the panel. Due to the outward bending, the tensile thermal stress on the outer surface of the skirt is further increased. In addition, this portion is easily damaged and the strength is reduced, and a tensile vacuum stress is further applied. Therefore, strengthening this portion of the panel portion is effective in preventing the damage.

Therefore, the present invention is characterized in that the reinforcing compressive stress value σ _C at least in the vicinity of the mold match 12 on the side surface of the skirt portion 6 is set to 5 MPa ≦ | σ _C | ≦ 14 MPa. The reason for setting 5 MPa ≦ | σ _C | ≦ 14 MPa is that if | σ _C | is smaller than 5 MPa, the thermal stress and the tensile vacuum stress generated near the mold match cannot be sufficiently offset. As a result, damage prevention in the heat treatment step becomes insufficient. Also, | σ _C |
If it is attempted to increase the size, it becomes difficult to increase the unbalance of cooling during the molding process of the panel portion and to uniformly strengthen the cooling portion. As a result, the breakage rate in the heat treatment process increases. | σ _C | is more preferably 7 to 11 MPa. The reinforcing compressive stress value near the mold match is conveniently measured at the skirt portion adjacent to the mold match portion.

Further, according to the present invention, the thickness T _S of the sealing end face of the skirt portion 6 is set to 0.43 with respect to the thickness T _L of the effective screen end.
Is set to _{≦ T S / T L ≦ 0.50} . T _S / T _L <0.43
In this case, the skirt 6 becomes too thin,
It is difficult to reliably and sufficiently perform the physical strengthening. If T _S / T _L > 0.50, the thermal stress increases, the breakage rate increases, and the mass increases. In addition,
It is more preferable that 0.44 ≦ T _S / T _L ≦ 0.48.

Further, in the present invention, the thickness of the body portion 7 of the funnel portion 2 is reduced as much as possible to reduce the weight of the funnel portion 2. Generally, it is preferable that the thickness of the body portion 7 is thinner from the viewpoint of weight reduction and cost. However, when the thickness is too small, the heat capacity is further reduced, and the thermal stress is increased as described above, which causes a problem. The present invention optimizes the thickness of the pair of panel portions and the funnel portion to be sealed from the viewpoint of generated stress, so that the body portion 7 of the funnel portion 2 can be made thinner than before, and the thermal stress and the cathode ray can be reduced. The pipe is designed not to affect the explosion-proof strength.

That is, the body 7 of the funnel 2
Assuming that the length dimension of the portion (between the sealing end face with the panel portion and the yoke portion 8) in the tube axis Z direction is B, the thickness _TF at the position of B / 2 is 0. 37 ≦ _TF / T
_C ≦ 0.49. By setting T _F / T _C ≧ 0.37, an increase in thermal stress is suppressed, and a synergistic effect with the above-described effect of the physical strengthening can be achieved to increase the effect of preventing damage to the panel portion.

On the other hand, when T _F / T _C <0.37, not only does the body portion 7 become so thin that the required strength cannot be obtained, but also the cooling or heating speed is increased. It becomes too hot and increases thermal stress. Also, T _F / T _C
If> 0.49, the effect of reducing thermal stress can be obtained,
Since the mass of the funnel portion increases, there is a disadvantage in terms of marketability and economy. Therefore, T _F / T _C is 0.390
It is more preferable if it is 0.430.

The reason why the thickness of the body portion 7 is defined at the position of B / 2 is that the middle of the body portion 7 is suitable as a position for specifying the thickness of the smoothly continuous body portion. is there.

FIG. 3 shows the stress (the sum of the strengthening compressive stress, the thermal stress and the vacuum stress) generated in the glass bulb of the present invention and the glass bulb with the skirt portion 6 thinned, particularly in the heat treatment step. This is a representation of the stress at an easy place. In FIG. 3, a solid line 10 illustrates the stress distribution of the glass bulb of the present invention.
A broken line 11 indicates a stress distribution generated in the glass bulb that is not optimally thick because the skirt portion 6 is thinned as indicated by the imaginary line 14. Each is a tensile stress, and the length of the arrow 13 indicates the magnitude of the stress. As is clear from comparison between the solid line 10 and the two-dot broken line 11, the stress generated in the glass bulb according to the present invention is suppressed and reduced.

While the embodiment of the present invention has been described with respect to a glass bulb having a large effective screen end at the short axis of the face portion, portions other than the short axis are the same as or smaller than the short axis as described above. Glass bulb can be designed with low setting.

[0032]

EXAMPLES Examples of the present invention and comparative examples of glass bulbs for 17-inch color cathode ray tubes having an aspect ratio of 4: 3 are shown in Table 1. The outer surface of the face is almost flat (all surfaces have a minimum radius of curvature of 50,000 mm).
, And the and the thickness distribution of the face portion of the panel section, i.e. the thickness of the effective screen edge portion a central thickness of T _L and the face portion in a ratio T _{L /} T _C all 1.8 and T _C is there. Then, towards the effective screen edge thickness is the long axis of the face portion of the panel portion used since thicker than the short axis, the thickness of the effective screen edge of the major axis and the T _L. All the panel parts except Comparative Example 1 were manufactured under the same strengthening conditions. The breakage rate is organized by the Weibull statistical method to determine the relationship between the stress of each part of the glass and the probability of breakage,
This was estimated by statistically rearranging the entire outer surface of the glass bulb. Note that, in Table 1, the M strengthening compressive stress is the strengthening compressive stress near the mold match, and the unit of the wall thickness is mm. The position of the effective screen edge is based on the standard of the Japan Electronics and Information Technology Industries Association EIAJ ED-2.
136B.

In Examples 1 to 3, the increase in thermal stress is suppressed, so that the breakage rate can be maintained within an allowable range. On the other hand, in Comparative Example 1, although the mass of the funnel portion was light, the reinforcing compressive stress value near the mold match was substantially zero because it was not reinforced, and the thermal stress was large, so the breakage rate was very high. Comparative Example 2 has a standard reinforced compressive stress value, but a large thermal stress is generated due to improper balance of the entire glass bulb, resulting in a high breakage rate. In Comparative Example 3, the thermal stress can be reduced by increasing the thickness of the body portion of the funnel portion, so that the breakage rate is low but the mass is heavy.

[0034]

[Table 1]

Examples 4 and 5 relating to a glass bulb for a 29-inch cathode ray tube having an aspect ratio of 4: 3 will be described in Example 1 described above.
The results are shown in Table 2 together with Comparative Examples 4 and 5 in the same manner as in Examples 3 to 3. If the panel portion used in these Examples and Comparative Examples, since the wall thickness of the effective screen edge is thicker than the long axis direction of the short axis, the thickness of the short axis was T _L. As is clear from Table 2, in each of Examples 4 and 5, the thermal stress can be suppressed, so that the breakage rate can be maintained in an allowable range. On the other hand, in Comparative Example 4, the thermal stress increases and the breakage rate is high. In Comparative Example 5, the breakage rate was low, but the mass of the funnel was considerably increased.

[0036]

[Table 2]

[0037]

According to the present invention, as described above, when a cathode ray tube is manufactured by combining a panel part having a large face part thickness distribution with a funnel part, the thickness of the skirt part is determined by the width of the sealing end face. Since the thickness is made appropriate for the peripheral thickness of the face portion, the thermal stress generated in the glass bulb in the heat treatment step can be suppressed, and the compressive stress due to physical strengthening can be effectively applied. Thereby, breakage of the glass bulb in the heat treatment step can be prevented or reduced.

Further, since the thickness of the body portion of the funnel portion is made appropriate for the thickness of the center portion of the face portion, the thermal stress due to the effect of the funnel portion can be minimized. This prevents or suppresses breakage of the glass bulb in the heat treatment step, and at the same time, reduces the weight of the funnel while maintaining the strength of the glass bulb. In addition, the thickness of the face portion of the panel portion can be reduced by implementing the present invention, without reducing the productivity compared to the conventional panel portion.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view taken along the line AA of FIG. 2 of a glass bulb for a cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a plan view of a face portion of the panel portion.

FIG. 3 is a distribution diagram of stress (thermal stress and vacuum stress) generated in the glass bulb of FIG. 1;

[Explanation of symbols]

 1: Panel part 2: Funnel part 3: Neck part 4: Face part 5: Blend part 6: Skirt part 7: Body part 8: Yoke part 9: Effective screen end part 12: Mold match

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoya Shimizu 1-1-10 Kitahonmachi, Funabashi City, Chiba Prefecture Inside Asahi Glass Co., Ltd. (72) Inventor Toshihide Murakami 1-10-1, Kitahonmachi, Funabashi City, Chiba Prefecture No. Asahi Glass Co., Ltd. F-term (reference) 5C032 AA01 BB02 BB10 BB13 BB20

Claims (2)

[Claims] 1. A panel having a rectangular face having a substantially flat outer surface and a concave curved inner surface, a skirt extending substantially perpendicular to the periphery of the face, and A funnel part connected to one end of the funnel part, and a neck part connected to the other end of the funnel part,
At least the panel portion is a glass bulb for a cathode ray tube to which a compressive stress is applied by physical strengthening, and the panel portion is a face portion of an effective screen end on a short axis and an effective screen end on a long axis. Among them, at the end of the effective screen having a larger thickness, 1) when the center thickness of the face portion is T _C and the thickness of the end of the effective screen is _TL , 1.70 ≦ _TL / T _C , 2) The reinforcing compressive stress value σ _C at least in the vicinity of the mold match on the side surface of the skirt portion is 5 MPa ≦ | σ _C | ≦
3) When the thickness of the sealing end face of the skirt portion is T _S , 0.43 ≦ T _S / T _L ≦ 0.50, and the funnel portion is: 4) the sealing of the funnel portion. Assuming that the length dimension in the tube axis direction of the body portion formed between the attachment end portion and the yoke portion is B, the thickness _{TF at} the position of B / 2 is 0.37 ≦ _TF / T.
_A glass bulb for a cathode ray tube, wherein _C ≦ 0.49. 2. A cathode ray tube manufactured by sealing the panel portion and the funnel portion.