JP2904067B2 - Glass bulb for cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube having a glass bulb for use mainly in televisions and the like.

[0002]

2. Description of the Related Art As shown in a partial sectional view of FIG. 1, a cathode ray tube 1 used for a television or the like basically includes a panel section 3 for displaying an image, and a funnel section 4 for mounting a deflection coil.
And a glass bulb 2 comprising a neck portion 5 for storing an electron gun 17.

In FIG. 1, reference numeral 6 denotes a panel skirt portion, 7 denotes a panel face portion for displaying an image, 8 denotes an explosion-proof reinforcing band for maintaining strength, and 10 denotes a panel portion 3 and a funnel portion 4 which are sealed with solder glass or the like. Sealing portion, 12 is a fluorescent film that emits fluorescent light by irradiation with an electron beam, 13 is an aluminum film that prevents the return of the fluorescent light, 14 is a shadow mask that defines the irradiation position of the electron beam, and 15 is a shadow mask that forms a panel skirt portion. 6 stud pins for fixing to the inner surface,
Reference numeral 16 denotes an interior tag for preventing high charge of the shadow mask 14 due to an electron beam and for conducting and grounding to the outside. Also, A
Indicates a tube axis connecting the center axis of the neck portion 5 and the center of the panel portion 3.

A glass bulb of a cathode ray tube as a vacuum vessel generates a stress (hereinafter referred to as a vacuum stress) because atmospheric pressure is applied to an outer surface thereof, but a tensile stress (hereinafter referred to as a vacuum stress) caused by an asymmetric structure different from a spherical shell. The region of (+ sign) exists relatively widely as shown in FIG. 2 together with the compressive stress (-sign). Here, σ _{R in} FIG. 2 is the stress along the paper surface, σ _T
Indicates a stress component in a direction perpendicular to the paper surface. The numbers along the stress distribution in the figure indicate the stress value at that position.

[0005] A two-dimensional stress distribution exists on the surface of the glass bulb, and the maximum value of the tensile vacuum stress usually exists at the end of the image display surface of the panel glass face or the side wall of the panel glass. Therefore, if the tensile vacuum stress of the cathode ray glass bulb is large and the structural strength is not sufficient, static fatigue failure occurs due to atmospheric pressure, and the cathode ray tube cannot function as a cathode ray tube. Further, in the manufacturing process of the cathode ray tube, particularly when the gas is exhausted while being kept at a high temperature of about 380 ° C., thermal stress is generated in the heat process and is added to the vacuum stress. The reaction can cause severe implosion, causing damage to surroundings.

As a guarantee for preventing such destruction, taking into account the strength of damage to the glass surface generated in the process of assembling the glass bulb and the cathode ray tube, the practical life of the cathode ray tube, etc. An external pressure load test is performed by applying air pressure or water pressure to a glass bulb that has been uniformly damaged with emery paper, and the internal / external pressure difference at the time of destruction is determined. I have.

As shown in FIG. 2, the structural breaking strength of a glass bulb that has undergone such damage depends on the structure of the glass bulb due to the vacuum stress existing on the outer surface of the glass bulb. Therefore, it cannot be determined uniquely. FIG. 3 shows the breaking strength of various television receiving glass bulbs made of the same material, but the minimum value is at most 190 kg / cm ² and the average is only about 250 kg / cm ² .

On the other hand, considering fatigue fracture due to vacuum stress, since the probability of fracture starting from the region where the maximum tensile vacuum stress σ _VTmax exists is high, the internal-external pressure difference, which is the guaranteed value of the pressure resistance described above, is 3 _%. In order to obtain a cathode ray tube glass bulb having a strength equal to or higher than the atmospheric pressure, the linearity of the elastic body conforms to the glass bulb, so that 3.0σ _VTmax <σ
_What is necessary is to satisfy the conditions of _SG . That is, σ _VTmax <σ _SG
Conventionally, as shown in FIG. 2, the geometric structure such as the thickness and shape of the glass bulb is determined so that σ _VTmax is suppressed to ₆₀ to 90 kg / cm ² .

[0009]

However, in order to guarantee the pressure resistance, σ _VTmax should be 60 to 90 kg / c as described above.
With a glass bulb structure defined as m ² , for example, the weight of the panel portion used for a cathode ray tube glass bulb for a color television having an effective screen (viewing area) having an aspect ratio of 4: 3 (horizontal: vertical) is as follows. , Almost 2.0 of its maximum outer diameter
Since it increases in proportion to the power of 2.4, the productivity of a large-sized cathode ray tube, particularly the productivity of a glass bulb, is extremely reduced, and the material cost is greatly increased.

As a solution to such a problem,
For example, it is conceivable that the surface of the glass bulb is strengthened by ion exchange treatment to reduce the weight. This method
This is a method in which alkali ions in the glass are replaced with larger ions at a temperature lower than the slow cooling region, and a compressive stress is created on the surface by increasing the volume. For example, Na ₂ O
SiO ₂ —SrO containing 8% and about 5 to 9% of K ₂ O
-BaO-Al ₂ O ₃ -ZnO ₂ line panel glass (Asahi Glass Co. 5001 glass), and held at about 450 ° C. KNO
It is obtained by immersion in the melt of Step ₃ for about 4 to 6 hours.

By this treatment, the surface of the panel glass 15
It is about 100-3000 kg / cm ² in size and has a depth of 10
A compressed layer having a depth of about 30 μm is formed. In the case of this tempering method, a large tensile stress layer is not formed inside the glass, but the thickness of the obtained compressive stress layer is small. As shown in Table 1, the depth is equal to or less than the depth of the damage caused by # 150 emery paper. Therefore, it is conceivable that scratches that pass through the stress layer during manufacturing or during use are obtained,
In that case, there is a problem that the effect of the reinforcement is lost.

It is also known that the surface of glass can be strengthened by air cooling. In this method, glass is heated to a temperature slightly lower than the softening point, and then blown with air to rapidly cool the glass to form a compressive stress layer of about 500 to 1000 kg / cm ² on the glass surface.

That is, since the surface is rapidly cooled while being maintained in a temperature range where the softening of the glass slightly occurs, there is a slight deformation after the treatment, so that there is a problem as a method for strengthening a panel glass for a cathode ray tube which requires strict dimensional accuracy. Is big. At the same time as the formation of the compression layer, a tensile stress layer having a size half the absolute value of the compression stress is formed inside the glass. Therefore, if a crack propagates inside the glass, it will self-detonate in an attempt to release the energy of the stored tensile strain, so in a vacuum vessel such as a cathode ray tube, a tensile stress layer that is too large from the point of implosion becomes a problem. .

An object of the present invention is to solve the above-mentioned drawbacks in the prior art, to strengthen the surface of a glass bulb while ensuring safety so as not to cause implosion of a cathode ray tube, and to obtain a compressive stress value on the surface. In view of the above, an object of the present invention is to provide a cathode ray tube glass bulb which is lighter than the conventional one.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a first invention comprises a panel having a substantially rectangular panel face, a funnel, and a neck. In the glass bulb for a cathode ray tube, a compression layer having a compressive stress σ _KC is formed by physical strengthening in at least a region of a panel portion of the glass bulb, and the compressive stress σ _KC has a breaking strength σ _{SG of the} glass bulb. 1 <Cσ _VTmax , between the maximum tensile vacuum stress σ _VTmax which is the maximum value of the tensile stress generated when atmospheric pressure is applied to the surface of the glass bulb having a vacuum inside.
_{/ Σ SG ≦ 1- (σ KC} / σ SG) consists (where 2 ≦ C ≦ 4)
And the compressive stress σ _KC is σ _KC ≦ −30.
kg / cm ² , and the compressive stress of the skirt is
Less than 100% der Rukoto more than 50% compressive stress of the part to provide a cathode-ray tube glass bulb, wherein.

According to a second aspect of the present invention, when the number of glass bulbs is small,
Having a compressive stress sigma _KC by physically strengthened in the area of the panel portion
Glass bulb with a vacuum layer inside
Caused by atmospheric pressure applied to the surface of
The maximum tensile vacuum stress σ _VTmax the panel, which is the maximum value of stress
A glass bulb for an cathode ray tube which is present at the end of the image display surface of the portion and has a breaking strength of σ _SG , wherein the thickness of the panel face portion is varied while keeping the inner and outer surface shapes constant. When the thickness at the center of the panel face is t ₀ such that σ _VTmax = σ _SG / C (where 2 ≦ C ≦ 4), the thickness t _{1 at the} center of the panel face is σ _SG / (Σ _SG −
σ _KC ) ≦ (t ₁ / t ₀ ) ² , 0.64 ≦ (t ₁ / t ₀ )
² <and have a 1 the relationship, and the compressive stress sigma _KC is
a σ _KC ≦ -30kg / cm ^2, compression response skirt
When the force is 50% or more and less than 100% of the compressive stress of the face part
Oh to provide a cathode-ray tube glass bulb which is characterized in Rukoto.

In the second invention, (t ₁ / t ₀ )
_{^2, 0.64 ≦ (t 1 / t} 0) 2 <1 to it必
It is important . If it is smaller than 0.64, the thickness of the face portion becomes thin, and it becomes easy to implode. If t ₁ = t ₀ ,
It will not be possible to make it thinner and lighter.

In the present invention, the maximum value of the tensile stress σ
_VTmax is 70 to ₁₅₀ kg / cm ² , which is a value determined in terms of the structure of the glass, and can be set to a value equal to or larger than the conventional value.

The compressive stress σ _KC is specifically −3.
It is necessary that the pressure be 0 kg / cm ² or less in order to effectively reduce the weight of the glass bulb for a cathode ray tube, increase the pressure resistance, and suppress the rate of implosion. The smaller the compressive stress σ _KC , the better for strengthening the glass bulb for a cathode ray tube, but it is practically difficult to reduce it to about −300 kg / cm ² or less by physical strengthening.
It is good to be up to 0 kg / cm ² .

The value of C is equal to the internal / external pressure difference that can withstand the pressure and the pressure resistance (see Tables 4 and 5) so as to be compatible with the environment in which the glass bulb is used and satisfy the required conditions such as safety.
It is an initial set value (unit: kg / cm ² ) of P).
If a certain value of σ _KC is set so as to satisfy the conditional expression of the present invention with respect to the setting of a certain value of C, the pressure resistance P is eventually improved and C ≦ P. σ _VTmax and σ _SG are values substantially determined by the shape of the glass bulb.

That is, for a specific C, specific σ _KC , σ _VTmax , and σ _SG satisfying the conditional expressions can be determined. It is necessary that the range of C be 2 ≦ C ≦ 4, whereby a glass bulb can be manufactured with a wider pressure resistance strength P than before.

In the case of C <2, σ _SG / C (= σ _VTmax ) becomes too large, and natural implosion due to delayed destruction is likely to occur, which is not suitable. In the case of C> 4, σ _VTmax is too small. That is, σ _KC becomes too large,
Forming an excessively large σ _KC is not suitable because it leads to a decrease in productivity and is not practical. When C = 3, the pressure resistance P becomes 3 or more, and a glass bulb having a guaranteed value of 3 or more in pressure resistance can be provided, which is preferable.

In the present invention, when the portion where the maximum tensile vacuum stress occurs in the panel portion is the outer surface of the face portion, the compressive stress of the face portion should be larger than the compressive stress of the skirt portion of the panel portion. It is necessary to prevent crack growth on the glass surface due to maximum tensile vacuum stress and prevent implosion. In this case, the compressive stress of the skirt is 50% or more and less than 100% of the compressive stress of the face.

If the compressive stress of the skirt portion is larger than that of the face portion, it is not possible to prevent deformation of the panel glass after cooling by twisting. On the other hand, if the compressive stress of the skirt is smaller than 50% of the compressive stress of the face, the skirt is not strengthened, so that it is necessary to increase the thickness.
There is a problem that weight reduction cannot be achieved.

In the panel part in which the compressive stress of the face part is larger than the compressive stress of the skirt part, cooling air is mainly applied to the face part of the panel part until the temperature of the glass falls to the strain point. It is manufactured by By such a method, the face portion is cooled faster than the skirt portion of the panel portion, and a large compressive stress is formed.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a glass bulb for a cathode ray tube having a glass bulb comprising a panel portion, a funnel portion and a neck portion, which is so large that physical strengthening does not lead to implosion of the cathode ray tube. (Compressive stress σ _KC due to reinforcement. In the present invention, since the tensile stress is represented by a positive value, the compressive stress is represented by a negative value.)
To form In particular, the impractical deviation in the dimensional accuracy of the panel glass does not occur, and the allowable range of the maximum tensile vacuum stress σ _VTmax determined by the mechanical properties of the glass bulb and the structure of the glass bulb in relation to the compressive stress σ _KC has been Provided is a cathode ray tube glass bulb having a lightened cathode ray tube with a structure that can be further increased.

In a particularly preferred embodiment of the present invention, the magnitude of the absolute value of the compressive stress σ _KC is determined by the relation of | σ _KC | ≦ σ _{SG to} the structurally essential fracture strength σ _{SG of the} glass. The maximum value σ _VTmax of the tensile vacuum stress which is determined structurally is σ _SG / C <σ _VTmax <(σ _{SG −σ KC} ) / C
It is mentioned that it becomes.

Further, in the present invention, the maximum value σ _VTmax of the tensile stress is determined depending on the distribution of the shape and thickness of the panel, in the case where it exists on the short axis of the effective screen edge on the outer surface of the face part and in the case where it exists on the long axis. is there. The short axis and the long axis are
An axis parallel to the short side of the panel passing through the center of the panel face outer surface and an axis parallel to the long side of the panel passing through the center of the panel face outer surface are meant.

Furthermore the compressive stress sigma _KC, rather than the side wall portion of the panel portion is larger than towards the face portion, it forms a compressive stress layer by cooling rapidly the face portion from the side wall (skirt) of the glass panel By doing so, the deformation of the face portion due to the shrinkage and solidification of the side wall portion is suppressed, and the accuracy of curvature of the inner surface of the face portion can be improved.

When the skirt portion is cooled faster and stronger than the face portion, the face portion undergoes a large deformation due to the movement of the skirt portion when the panel portion is cooled and solidified. Therefore, since the accuracy of the curvature of the inner surface of the face portion fluctuates and becomes unstable, in the case of a color picture tube using such a glass panel, a landing characteristic of an electron beam becomes poor, and a stable color image cannot be obtained.

According to the present invention, it is possible to minimize the deformation of the face portion due to the shrinkage effect accompanying the cooling and solidification of the skirt portion of the glass panel.

According to the present invention, as described above, the ion exchange strengthening method in which the compressive stress value is large but the thickness of the compressive layer cannot be sufficiently obtained, or an excessive tensile stress is introduced into the glass, resulting in implosion of the cathode ray tube. It is not based on the air-cooling strengthening method that cannot obtain a stable compressive stress when trying to suppress the internal tensile stress, but by controlling the cooling rate and holding temperature during slow cooling after glass molding, This is to perform physical strengthening to obtain a high compressive stress.

The present inventors have made it possible to reduce the wall thickness of the glass bulb compared to the conventional bulb by specifying the magnitude of the allowable compressive stress by experiments, thereby realizing a glass bulb which is lighter without causing implosion. Was. Further, the shape of the panel face portion may be any one of a spherical surface, a cylindrical surface, and an aspherical surface. However, the present invention has a great advantage when applied to an HDTV (High Definition TV) panel having a large aspect ratio and an aspheric surface.

In the physical strengthening, when the glass is rapidly cooled from a high temperature region near the softening point, the surface rapidly shrinks and solidifies, but the inside still retains sufficient fluidity and remains in an expanded state. Instantaneously relaxes. Upon further cooling, the interior also tends to shrink, but its movement is limited by the presence of a solidified surface layer. As a result, when the temperature of the glass drops to room temperature and reaches a sufficient equilibrium state, a large compressive stress layer is formed on the surface and a tensile stress layer is formed inside, and remains as residual stress.

At this time, the magnitude of the generated stress depends on the time required for the glass surface to decrease from the annealing temperature to the strain point. The earlier the cooling is, the larger the difference in shrinkage from the inside becomes, and the cooling ends. Thereafter, a compressive stress σ _KC having a large absolute value is generated on the surface. However, at the same time, a tensile stress of σ _KT = −σ _KC / 2 is inevitably formed in the center of the inside in such a manner as to cancel the compressive stress.

Normally, in a cathode ray tube for television reception having a maximum outer diameter of 15 cm or more, the outer surface of the skirt portion of the cathode ray tube panel portion is subjected to a treatment such as tightening with a metal explosion-proof band, and the size considered in handling is considered. Even if a shock is applied to the cathode ray tube, the cathode ray tube is not broken and safety is ensured.

Even if the cathode ray tube glass bulb is broken by an impact, in order to secure the safety of the user, the U.S. UL safety standard applies a shock to the cathode ray tube and scatters the glass at that time. The safety is determined by the following two methods, such as judging whether or not it is possible based on the magnitude of the quantity.

One is a diamond cutter with a length of 10c.
After the m scratches are placed in the upper and lower two places on the long side near the effective screen display end of the panel face portion, the face portion is impacted with a missile-shaped steel object so as to give energy of up to 20 joules. A test in which the cathode ray tube is destroyed by the impact and a pass / fail judgment is made based on the size of the glass pieces scattered at that time, and is called a missile method.

The other is a test in which a steel ball having a diameter of 50 mm is dropped in a pendulum shape on the effective screen of the panel face with an energy of 7 joules, and a pass / fail judgment is made based on the size of the scattered glass fragments. Called the law.

In these destructive tests, when sudden implosion occurs, the amount of scattered glass increases, and the probability of rejection is high. In addition, a test called the guillotine method has been performed to confirm safety, and a part corresponding to the upper part of the funnel from the top of the cabinet containing the cathode ray tube,
An upright steel rod gives an impact of about 61 joules of energy.

The guillotine method is a test in which a large amount of energy is applied to a TV set to forcibly damage or destroy it, and it cannot be said that the guillotine method assumes an impact which occurs in ordinary daily life. . Therefore, the guillotine method was deleted from the U.S. safety standards in 1992 except for a front-reinforced valve in which safety glass or the like was adhered to the face surface, and has not been adopted in the present invention.

In the present invention, in order to confirm the influence of the presence of the stress layer due to the physical strengthening on the safety, the allowable range of σ _KT was determined based on the presence or absence of implosion using these tests. Table 1 shows the depth of flaws that occur when the panel glass is injured using various injuries. In the missile method, as shown in Table 1, the depth of the scratch made by the diamond cutter is at most 140 μm, but the thickness of the compression layer is sufficiently thick because the thickness of the compression layer is approximately 1/6 of the glass thickness. The greater the absolute value of the stress value σ _KC, the greater the degree to which crack propagation from the scratch was inhibited and the more stable the tendency.

[0043]

[Table 1]

On the other hand, in the ball impact method, since there is a compressive stress layer on the outer surface of the panel glass, only a small hertz crack-like dent is formed at the impact portion, and the rate of occurrence of rebound which does not cause cracks in the glass increases. Showed a trend. This tendency was observed as the absolute value of the compressive stress value σ _KC increased.

When a glass bulb having such a surface compressive stress layer is assembled as a cathode ray tube and the inside is evacuated, the stress σ generated on the outer surface is based on the principle of superposition of the stress on the linear elastic body. , The sum of the vacuum stress σ _V and the surface compressive stress σ _KC , that is, σ = σ _V + σ _KC .

As a guarantee that the cathode ray tube will not be destroyed during the manufacturing process or use thereof, it is necessary to be able to withstand the case where the pressure difference between inside and outside is C atm in the above-mentioned pressure resistance test. When the C pressure is given as the pressure difference between the inside and outside, the magnitude of the stress generated on the surface of the cathode ray tube glass bulb is σ = C
It has changed to σ _V + σ _KC .

Therefore, _assuming that the breaking strength of the glass bulb structurally is σ _SG and the maximum tensile vacuum stress at atmospheric pressure is σ _VTmax , the condition under which the glass bulb does not break is Cσ
_VTmax + σ _KC <σ _SG

On the other hand, in order to reduce the thickness and weight by physical strengthening, the condition of σ _SG / C <σ _VTmax must be satisfied, and eventually 1 / Cσ _SG <σ _VTmax <(σ _{SG −σ
KC} ) / C. That is, 1 <Cσ _VTmax / σ _SG <1
It has been found that satisfying the relationship of _{−σ KC} / σ _SG by σ _VTmax and σ _KC is a condition that can be safely reduced in weight by performing physical strengthening.

In the process of manufacturing a cathode ray tube for a color television, the panel and the funnel are connected to each other by using a PFS such as ASF1307 manufactured by Asahi Glass in order to improve the strength of the sealing area.
with _{bO-B 2 O 3 -ZnO-} BaO-SiO 2 based crystalline solder glass, and sealed by baking 35 minutes at about 440 ° C., a structure that is integrated as a glass bulb.

However, the bending strength of such a sintered body of solder glass is about 7 times that of panel glass or solder glass.
There is only 0%. Therefore, in order to prevent destruction from the sealing portion, the thickness of the panel and the funnel near the sealing portion is increased, and the vacuum tensile stress generated in the sealing portion is usually 60 kg / c.
It is suppressed to about m ^2.

By the way, in the manufacturing process of the cathode ray tube for color television, about 440
When firing at 35 ° C. for 35 minutes, sealing and cooling to room temperature, the compressive stress formed in the panel glass is relaxed by about 5%.
In the present invention, since the compressive stress is formed in consideration of the relaxation of the compressive stress, a sufficient compressive stress is obtained even after the panel glass and the funnel glass are sealed to produce a cathode ray tube for a color television. Remaining and strengthened.

The weight reduction of the panel portion can be obtained by reducing the thickness of either the panel face portion or the panel side wall portion (skirt portion). However, when the panel side wall portion is reduced in thickness, the sealing portion between the panel and the funnel is formed. Causes an increase in tensile vacuum stress,
The occurrence of destruction from the sealing portion becomes a problem. That is, it is preferable to achieve the weight reduction by reducing the thickness of the panel face portion.

Now, while keeping the curvature of the outer curved surface and the curvature of the inner curved surface of the panel face portion constant, one of them is moved in parallel to reduce the thickness.

When the aspect ratio is 4: 3 or 16: 9,
On the short axis or long axis of the CRT glass bulb for revision
Tensile vacuum generated near the face image display edge
Stress σ_VTmax Is almost the square of the thickness of the face center.
Increases or decreases in proportion. Therefore, σ_VTmax = Σ_SG/ C
The center thickness of the face to be given is t₀ Then, the thickness is t ₁ 
The maximum tensile vacuum stress when_VTmax = (T
₀ / T₁ )^Two σ_SG/ C.

As described above, for a glass bulb having a compressive stress σ _KC due to physical strengthening, the allowable σ
The range of _VTmax is σ _SG / C <σ _VTmax <(σ _{SG −σ KC} ) /
Since C, σ _SG / (σ _SG −σ _KC ) <(t ₁ / t ₀ )
² <1. In other words, by reducing the center thickness t ₁ of the face portion in the range of the above expression, it is possible to achieve weight reduction without implosing the cathode ray tube.

[0056]

【Example】

(Embodiment 1) In this embodiment, a CRT generally used for a color television cathode ray tube as shown in FIG.
= 3, a glass bulb having the properties shown in Table 2 and having the composition (unit:% by weight) shown in Table 3 was prepared. The components in FIG. 1 are the same as those in the related art, except that the stress distribution of the glass bulb 2 and the thickness of the panel face portion 7 are reduced, so that the description thereof is omitted. The “name” in Tables 2 and 3 is a trade name (made by Asahi Glass).

The glass bulb has an aspect ratio of 4: 3.
It has the same shape and dimensions as those of a conventional product for a 29-inch television having an effective screen with a diagonal diameter of 68 cm. At the time of design, the inner curved surface of the panel face portion is moved outward in parallel along the pipe axis connecting the panel face and the center of the neck to reduce the thickness, and the center thickness of the face is 14 mm.
Is changed to 13 mm from the conventional product.

[0058]

[Table 2]

[0059]

[Table 3]

When the inside of the glass bulb is evacuated and evacuated, a maximum tensile vacuum stress σ _VTmax is formed on the short axis of the effective screen edge on the outer surface of the face portion. Table 4 shows the values.

[0061]

[Table 4]

This value is obtained when the center thickness of the panel face is 14
mm was 84 kg / cm ² in the conventional product, but 97 kg / cm ² when the face center thickness was reduced to 13 mm.
cm ² .

Next, at the time of slow cooling after molding the thinned panel, the cooling rate and the holding temperature are controlled to form a compressive stress layer having various σ _KC values almost uniformly on the outer and inner surfaces of the panel. did. These values of σ _KC are shown in Tables 3 to 7 in Table 4.

In order to confirm the relationship between the compressive stress value σ _KC formed on the panel surface and the strength in this manner, the reinforced panel and the funnel were sealed to form a glass bulb, and a pressure resistance test was performed. Explosion-proof processing was performed after exhaustion, and the explosion-proof test was performed by the missile method and the ball impact method described above.

In the case of a conventional glass bulb using a panel having a face center thickness of 14 mm, the pressure resistance is about 3.0.
kg / cm ² . On the other hand, in the case of an untempered glass bulb using a thinned panel having a face center thickness of 13 mm, the pressure resistance decreased to 2.6 kg / cm ² . When the breaking strength σ _SG of these two is calculated, about 250 kg /
cm ² .

When the pressure resistance of the thinned tempered glass bulb is determined, as shown in FIG.
The relationship _SG = P · σ _VT + σ _KC holds. It was found that as the absolute value of the compressive stress σ _KC increases, the value of the compressive strength P increases. However, σ _VTmax <(σ _{SG −σ KC} ) /
Case 3 that does not satisfy 3 has a pressure resistance of 2.9 kg
/ Cm ² , and C = 3.0 (kg / cm ² ) could not be guaranteed.

Next, the difference in the rate of implosion was determined by performing a missile test. As the absolute value of the compressive stress increased, the effect of preventing the growth of cracks caused by the expansion of the scratches previously placed at the end of the effective face of the face. Showed a tendency to stabilize.

Further, a ball impact test was performed, and a difference in the rate of implosion was determined in the same manner as in the missile test.
As shown in Case 2, implosion occurred at the corner of the unreinforced glass bulb (25 mm inside the effective screen edge), but the implosion rate decreased as the absolute value of the compressive stress σ _KC increased, In addition, the effect of inhibiting the occurrence of cracks tended to increase the rate of rebound.

Example 2 In this example, the aspect ratio was almost 16: 9 in order to confirm the influence of the structural factor of the glass bulb and the influence of the set pressure resistance C.
Example 1 of a horizontally long 32-inch television glass bulb having an effective screen having a diagonal diameter of 76 cm in Example 1
The same evaluation was performed.

The center thickness of the face of the conventional panel for this 32-inch television is 14.5 mm and C = 3, but C = 2.8 and the face center thickness is 14.0, 1
The thickness was reduced to 3.5 and 13.0, and the thickness was further reduced to C = 2.5 and the center thickness of the face was set to 12.5 mm.
Also in this embodiment, the maximum tensile vacuum stress σ _VTmax is formed on the short axis of the effective surface end of the outer surface of the face portion, and the breaking strength σ _SG measured by performing a pressure resistance test on this glass bulb is approximately 260 kg / cm ^2. Met. Table 5 shows the compressive stress value σ _KC formed on the panel surface by the reinforcement.
It was shown to.

[0071]

[Table 5]

With respect to the pressure resistance, as shown in Table 5, when the thickness of the glass bulb is _reduced , σ _VTmax > (σ _{SG −σ KC} )
In case 4, the pressure resistance was less than 2.8 kg / cm ² , which was insufficient. In addition, implosions occurred in missile tests and ball impact tests.

On the other hand, compressive stress σ _KC ≦ −30 kg / cm ²
In cases 3, 5, and 6, which satisfy σ _VTmax <(σ _{SG −σ KC} ) / C, the pressure resistance strength is 2.8.
Due to the effect of preventing the crack growth caused by the compressive stress layer exceeding kg / cm ² , even in the missile test and the ball impact test, no implosion occurs and the ball is stable. In case 7 where C was 2.5, safety was confirmed in all of the pressure resistance, missile test, and ball impact test.

Further, as seen in Case 2, the compression stress σ _KC is reduced when implosion occurs in the ball impact test while satisfying σ _VTmax <(σ _{SG −σ KC} ) / C without reinforcement. In the added case 3, no implosion occurred, and the incidence of ball rebound increased.

(Embodiment 3) In this embodiment, a panel glass for a 29-inch television with an aspect ratio of 4: 3 and a diagonal diameter of 68 cm, which is the same as that of Embodiment 1, is used. As shown in the figure, the compressive stress σ _KC (kg / cm
² ) is made larger at the face portion than at the skirt portion on the outer surface of the panel portion.

In this case, when the panel glass is cooled from the annealing point to the strain point, cooling air is mainly applied to the face portion, and the face portion is rapidly cooled from the skirt portion.

[0077]

[Table 6]

Sample 1 is an example in which the compressive stress of the skirt portion is larger than the compressive stress of the face portion.
Is that the compressive stress of the skirt is 62
%, 60%, and 58%. Twist after cooling (μm)
Was determined by measuring the difference in height from the face surface at the center of the panel with respect to two diagonal lines connecting the skirt ends at the four corners of the panel. Each sample was measured on 100 panels. Comparing the average value of the torsion, the twist of Sample 1 is about 100 μm,
Each of Samples 2-4 was improved to less than 1/4 of Sample 1.

[0079]

According to the present invention, the physical strengthening for obtaining a stable compressive stress is performed by controlling the cooling rate and the holding temperature during the slow cooling after the glass molding of the glass bulb for a cathode ray tube. By specifying the size within a permissible range, the thickness of the glass bulb is made thinner than that of the conventional product, and there is an excellent effect that the glass bulb can be reduced in weight without causing implosion. In addition, there is also an effect that the thickness of the panel face portion, which has a small influence on the strength even if it is made thinner, can be made thinner to reduce the weight.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a television cathode ray tube for explaining a glass bulb of the present invention.

FIG. 2 is a stress distribution diagram of a conventional glass bulb for a 28-inch cathode ray tube.

FIG. 3 is a graph showing the breaking strength of various conventional glass bulbs for cathode ray tubes.

[Explanation of symbols]

 1: cathode ray tube 2: glass bulb 3: panel section 4: funnel section 5: neck section 6: panel skirt section 7: panel face section 8: explosion-proof reinforcing band 10: sealing section 12: fluorescent film 13: aluminum film 14: Shadow mask 15: Stud pin 16: Interior dug 17: Electron gun

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-129836 (JP, A) JP-A-7-142012 (JP, A) JP-A-7-142013 (JP, A) JP-A-57-2012 208042 (JP, A) JP-A-62-252050 (JP, A) JP-A-1-319232 (JP, A) JP-A-62-202446 (JP, A) JP-A-57-115155 (JP, U) U.S. Patent No. 2991591 (US, A) RCA Engineer Vol. 29 No. 5 Sept / Oct. 1984 Improved thermal process for color picture tube panel glass. Asahi Glass Research Report 34 [2] (1984) 12. Stress Analysis of Vacuum Glass Valve Using Finite Element Method and Application to Shape Design Glass Handbook p484-485 s50.9. 30 Asakura Shoten (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 29/86 H01J 9/24

Claims (3)

(57) [Claims] 1. A glass bulb for a cathode ray tube comprising a panel portion having a substantially rectangular panel face portion, a funnel portion and a neck portion, wherein at least a region of the panel portion of the glass bulb has a compression stress σ _KC by physical strengthening. A layer is formed, and the compressive stress σ _KC is the maximum value of the breaking strength σ _SG of the glass bulb and the tensile stress generated when atmospheric pressure is applied to the surface of the glass bulb having a vacuum inside. Between the maximum tensile vacuum stress σ _VTmax ,
_{1 <Cσ VTmax / σ SG ≦} 1- (σ KC / σ SG) ( provided that 2
≦ C ≦ 4) made has a relationship, and the compressive stress sigma _KC
Is σ _KC ≦ −30 kg / cm ² and the compression of the skirt is
Stress is 50% or more and less than 100% of the compressive stress of the face
Cathode-ray tube glass bulb, characterized in der Rukoto. 2. At least in the area of the panel part of the glass bulb
Compressed layer with compressive stress σ _KC is formed by physical strengthening
And the atmospheric pressure is negative on the surface of a glass bulb with a vacuum inside.
The maximum value of tensile stress generated by loading
Maximum tensile vacuum stress σ _VTmax is at the edge of the image display surface of the panel
The glass bulb for a cathode ray tube having a breaking strength of σ _SG and having a constant inner and outer surface shape of the panel face portion and varying the thickness, σ _VTmax = σ _SG
/ C (where 2 ≦ C ≦ 4), the thickness at the center of the panel face is t ₀ , and the thickness t _{1 at the} center of the panel face is σ _SG / (σ _SG −σ _KC ) ≦ (T ₁ / t ₀ )
^{_{2, 0.64 ≦ (t 1 /}} t 0) 2 < to have a 1 relationship:
And the compressive stress σ _KC is σ _KC ≦ −30 kg / cm
² , and the compressive stress of the skirt is
Cathode-ray tube glass bulb, wherein less than 100% der Rukoto 50% or more forces. 3. A skirt portion of the panel portion by applying cooling air mainly to a face portion of the panel portion before the surface of the panel portion of the glass bulb for a cathode ray tube falls from the annealing point to the strain point. 3. The glass bulb for a cathode ray tube according to claim 1, wherein the face portion is manufactured by quenching the face portion more rapidly.