KR100352305B1 - Manufacturing method for crt panel - Google Patents

Abstract

The present invention comprises the steps of: compressing a panel and then quenching the panel to a temperature region where at least some of the molecules constituting the panel cannot be rearranged; Reheating the quenched panel to a temperature above the ANNEALING POINT and maintaining it for a period of time to completely remove the dwarf; Quenching at least a portion of the molecules constituting the panel to a predetermined lower point (STRAIN POINT) such that rearrangement is not possible; And cooling the panel at a rate such that breakage due to transient distortion is not caused by the panel after the intermolecular rearrangement is completed by quenching. This not only increases the mechanical strength, but also minimizes the occurrence of planar stress, thereby improving thermal stability in the manufacturing process of the cathode ray tube and minimizing compaction to reduce mislanding. A method for producing a panel is provided.

Description

Manufacturing Method of Panel for Cathode Ray Tube {MANUFACTURING METHOD FOR CRT PANEL}

This invention relates to the manufacturing method of the panel for cathode ray tubes.

Generally, a cathode ray tube has a panel provided in front and projecting an image, a funnel-shaped funnel coupled to the rear of the panel, and a neck coupled to the government of the funnel and receiving an electron gun therein. Among these, the panel is a part where the image is projected directly to the outside and its intensity is a very important factor. In particular, since the cathode ray tube has been enlarged and planarized in recent years, attention has been focused on a method of manufacturing a panel that satisfies predetermined conditions inherent in strength and the like.

In the molding process of the panel, a molten glass material called a glass gob is introduced into a bottom mold forming a panel of a panel, and then pressurized by a plunger, thereby forming a gap between the lower mold and the plunger. Molded along the space. At this time, since the glass gob maintains a high temperature of about 1000 ° C., an appropriate cooling process immediately after the panel molding is an important factor for determining the strength of the panel.

As a method of controlling excessive transient distortion generated in the process of rapid cooling and solidification in a molding machine after pressure molding, the following method was conventionally used. First, the glass gob is pressurized and molded on a molding machine to minimize temporal distortion, and then is quenched and taken out of the mold. Then, the temporary distortion generated by cooling in the air is reheated above the annealing point of the glass and maintained for a certain time. After removing the temporary distortion due to temperature non-uniformity, and slowly cooling to room temperature has been used.

However, this method has an advantage that almost no unnecessary compaction is generated so that an incorrect misalignment of the shadow mask and the phosphor pixels is not generated in the assembly process of the cathode ray tube. The planarization is very susceptible to breakage due to transient distortion during the manufacturing process and subsequent breakdown in mechanical strength testing.

In order to compensate for this, there is also a method of increasing the thickness of the panel, in particular, the effective surface edge portion, but this causes a disadvantage of lowering the image quality of the effective surface edge portion and increasing the weight of the finished product.

In addition, as another method for manufacturing a panel, the panel may be quenched and then quenched to give a temporary transient distortion. In the following), a certain amount of surface compressive stress is present on the panel by maintaining a certain time and at the same time reducing the plane stress. This is called a low temperature treatment method.

In such a low temperature treatment method, the panel generates a certain amount of surface compressive stress due to the temperature difference in the thickness direction, thereby increasing the mechanical strength of the panel. However, when this method is applied, the cooling rate of the center of the effective surface and the fusion of the rear glass becomes relatively high in the forced cooling process after compression molding of the panel. Due to the slowest cooling rate, the temperature deviation in a single object of the panel immediately before the start of the low temperature treatment becomes very large, and remains in the form of excessive plane stress (Membrane Stress) even after the end of the low temperature treatment. In other words, the planar stress remaining in the panel after the low temperature treatment is a result of the addition of the factors of non-uniform cooling generated in the quenching process in the molding machine in addition to the factors caused by the shape characteristics (thickness) of the panel.

As a result, excessive residual plane stress (Membrane Stress) causes excessive mislanding in the manufacturing process of cathode ray tubes, and impairs stability of cathode ray tube breakage in various temperature rising and cooling processes. do. In addition, at the start of low temperature treatment, the effective surface edge and corner temperature are in the temperature range where glass molecules are rearranged smoothly, so the amount of relaxation of surface compressive stress during the low temperature treatment is relatively higher than that of the effective surface center. The result is that the stress is less than the maximum surface compressive stress in the center of the panel effective surface. These results do not meet the purpose of the formation of even surface compressive stress, particularly to enhance the surface compressive stress of the effective side edge, which is the weakest part of the cathode ray tube.

Therefore, it is urgent to develop a method for manufacturing a panel that satisfies predetermined conditions, that is, all of the following [Formula 1] to [Formula 4] by supplementing the disadvantages of the above methods.

[Equation]

[Equation 1]

σSC <σSA <σSB

[Equation 2]

σMA <σMB <σMC, (σMC <1.2σMB)

[Equation 3]

σMB <0.7σSB

[Equation 4]

5Mpa <σSB <15Mpa

Where σSA: maximum surface compressive stress at the center of the panel effective surface, σSB: maximum surface compressive stress at the panel effective surface, σSC: maximum surface compressive stress at the panel skirt, σMA: maximum surface stress at the center of the panel effective surface Maximum Plane Stress, σMC: Maximum Plane Stress of Panel Fusion.

Accordingly, an object of the present invention is to provide a method for producing a cathode ray tube panel that satisfies the above conditions, that is, [Formula 1] to [Formula 4], without increasing the thickness of the panel and changing the design. It is.

In addition, by satisfying the above conditions, not only can the mechanical strength be increased, but also the occurrence of planar stress can be minimized, thereby improving thermal stability and minimizing compaction in the cathode ray tube manufacturing process, thereby reducing mislanding. It is to provide a method for producing a cathode ray tube panel.

1 is a plan view of a panel according to the invention,

2 is a cross-sectional view taken along the line II-II of FIG. 1;

3 is a temperature curve according to the present invention,

Figure 4 is a comparison curve between the conventional and the present invention,

5 is a surface temperature curve for each 29FCD area during quench strengthening according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10 panel 12: effective surface

14: face portion 15: skirt portion

The object is, according to the present invention, compressing a panel and then quenching the panel to a temperature region where at least a portion of the molecules constituting the panel cannot be rearranged; Reheating the quenched panel to a temperature above the ANNEALING POINT and maintaining it for a period of time to completely remove the dwarf; Quenching at least a portion of the molecules constituting the panel to a predetermined lower point (STRAIN POINT) such that rearrangement is not possible; It is achieved by the method for producing a cathode ray tube panel, characterized in that the panel in which the intermolecular rearrangement is completed by quenching is cooled at a speed such that breakage due to transient distortion does not occur.

Here, the step of reheating the panel to a temperature above the slow cooling point, preferably has a temperature range of at least 5 ℃ to 20 ℃ higher than the predetermined slow cooling point.

At this time, the step of maintaining the panel at a temperature above the slow cooling point for a certain time, it is advantageous to take at least 10 minutes or more.

Meanwhile, the step of quenching to a predetermined lower limit temperature such that the highest temperature inside the panel is capable of rearrangement between molecules may be performed by cooling air, and the cooling air may have a temperature range of about 150 ° C to 300 ° C.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the panel 10 includes a face portion 14 having an effective surface 12 on which an image is actually projected, and a skirt portion 15 bent from a circumferential surface of the face portion 14. Have At this time, the measurement area of each part of the present invention, as shown in Figure 2, the maximum surface compressive stress (σSA) of the center portion of the effective surface 12 of the panel 10 and the center portion of the effective surface 12 of the panel 10 maximum Area A for measuring plane stress (sigma) MA, and B for measuring maximum surface compressive stress (sigma SB) at the side of the effective surface 12 of the panel 10 and the maximum plane stress (σMB) at the side of the effective surface 12 of the panel 10. The area and the C area for measuring the panel 10 skirt section 15 maximum surface compressive stress σ SC and the panel 10 fusion zone maximum plane stress σ MC are shown.

The present invention provides a first step of compressing a panel 10 and then quenching the panel 10 to a temperature region where at least some of the molecules constituting the panel 10 cannot be rearranged. A second step of reheating the panel 10 to a temperature above the ANNEALING POINT to maintain it for a certain time to completely remove the dwarf; and a predetermined lower limit such that at least a portion of the molecules constituting the panel 10 cannot be rearranged. A third step of quenching to a temperature (STRAIN POINT), and a fourth step of cooling the panel 10 at which the intermolecular rearrangement is completed by quenching at a speed such that breakage due to transient distortion does not occur.

This idea of the present invention will be described using the 29FCD panel 10 as an example. In the initial stage of region I of FIG. 3, the panel 10 has a very large temperature gradient (MAX.ΔT = 80 ° C. or more) over the entire surface of the panel 10. The cause of such a temperature gradient is, firstly, the difference in cooling rate due to the thickness distribution of the panel 10 and the uneven cooling effect in the cooling process in the mold after the pressing of the glass gob.

At this time, since the panel 10 having the cooling rate due to the thickness distribution has a skirt portion 15 around the periphery, the heat dissipation area is relatively small compared to the distribution of mass at the periphery, especially the corner portion. Means. In addition, the non-uniform cooling effect in the cooling process in the mold is cooling by blowing cold wind from the nozzle in the center of the inner surface of the panel 10 in this process, so that the cooling effect of the central portion of the inner surface is increased, and in particular, the inner corner portion is insufficient cooling. It means higher temperature than other parts. Here, the panel 10 formed in the lower mold is cooled by the cooling air toward the lower side of the lower mold.

As such, a very large temperature gradient resulting from forced cooling in the mold is naturally cooled until just before the first step after the panel 10 is taken out of the mold, and the temperature gradient across the entire surface of the panel 10 becomes larger. In addition, temporary distortion is the maximum.

Step A region of FIG. 3 is a section for raising the temperature of the panel 10 to a desired temperature. Predetermined desired temperature is slow cooling point + (alpha) = (alpha) = 5-20 degreeC in this invention, for example. In the case of the low temperature treatment described above, STRAIN POINT + α (α = 5 to 15 ° C.). At this time, in the present invention, the larger the α, the greater the amount of permanent distortion remaining after the end of cooling if the cooling rate is kept constant in the process II of FIG. In the case of low temperature treatment, the larger α is, the smaller the amount of permanent distortion remaining after the end of cooling.

Temporary distortions generated during cooling of the panel 10 and permanent distortions remaining after the end of cooling can be divided into cross-sectional stress and planar stress, depending on the cause of the occurrence of the panel stress. As the stress generated by the difference in cooling rate, after the end of cooling, compressive stress exists on the surface and tensile stress exists in the form of permanent stress.

MEMBRANE STRESS is a stress generated by the difference in cooling rate between thick and relatively thin parts in glass with a wide range of thickness distribution, such as panel 10. The surface of thick parts is cooled by slow cooling speed. After termination, the density of the constituent molecules is relatively large. Therefore, the tensile stress is present in the thick portion after the end of cooling, the compressive stress is present in the form of permanent stress in the relatively thin portion.

The larger the cooling rate, the larger the cross-sectional stress, and the larger the cooling rate difference for each part, the larger the plane stress. In general, in the glass manufacturing process having a wide thickness distribution, after quenching and quenching, a large plane stress is generated along with a very large cross-sectional stress. Useful physical properties, but the accompanying large plane stresses, increase beyond a certain amount, lead to thermal instability of the glass, causing breakage in the manufacturing process of the cathode ray tube, and due to excessive compaction during the heat treatment process, MISLANDING. Will cause. Therefore, the problem for increasing the strength of the glass is to minimize the plane stress while at the same time obtaining the cross-sectional stress of the desired size.

In order to satisfy the above problem, the intermolecular ash in the direction of relieving compaction at the same time to obtain the desired amount of cross-sectional stress by maintaining the glass in which excessive transient distortion is generated by rapid cooling at a temperature slightly higher than the distortion point of the glass. The method of minimizing the plane stress by adopting the arrangement is adopted. However, this method requires a relatively long heat treatment furnace because the holding time takes a long time, and the glass has an excessively long residence time in the production process, causing a decrease in production efficiency. In addition, it is possible to obtain the cross-sectional stress of the desired size, while maintaining the pattern of the plane stress due to non-uniform cooling in the forced cooling process along with the plane stress due to the thickness distribution has a limit in minimizing the plane stress.

Thus, in the present invention, the first section A section of FIG. 3 is formed as a section for heating up to a temperature region for completely removing the transient distortion of the glass. At this time, the peak temperature value is determined according to the cross-sectional stress value to be obtained. When the cooling rate is kept constant in the quench section, the higher the peak temperature value, the larger the cross-sectional stress value obtained after quenching. For example, in 29FCD, the change of the cross-sectional stress value of the short axis corner of GLASS effective surface 12 according to the peak temperature value is as follows.

Peak temperature (℃) Surface compressive stress (Mpa) Effective surface shortened corner surface average quenching speed (-℃ / min) 510 4.0 10 515 4.9 10 520 6.7 10 525 8.0 10

At this time, the slow cooling point (ANNEALING POINT) of the panel 10 shall be 510 degreeC.

Section I process B in FIG. 3 is a section that is completely removed by maintaining excessive transient distortion at a temperature above the slow cooling point. The retention time depends on the thickness of the glass and the peak temperature value, for example at least 10 MIN for 29FCD. Step II of FIG. 3 is a quench section, and the cooling rate is determined according to the stress value to be finally obtained. Surface compressive stress values according to cooling rate are as follows.

Effective surface shortened corner surface average quenching speed (-℃ / min) Surface compressive stress (Mpa) Peak temperature (℃) 10 6.7 520 13 8.2 520 16 9.5 520 20 10.6 520

At this time, the slow cooling point (ANNEALING POINT) of the panel 10 is 510 ° C, and the temperature of the cooling air required for cooling the panel 10 in the quench section is about 150 to 300 ° C. The quenching is continued until the panel 10 outer surface center temperature drops below the strain point, and the cooling rate is set to -5 to -25 ° C / min depending on the required cooling rate.

The panel 10 completely distorted in the peak holding section is cooled by the controlled cooling air in the quench section to have a cross-sectional stress of a desired size. At this time, the planar stress (MEMBRANE STRESS) is generated by the cooling rate difference according to the glass thickness distribution, which is relatively less than the result of the low temperature treatment method of the conventional invention. Below the strain point, the occurrence or disappearance of the strain due to the viscous flow of the glass disappears. However, the temporary stress due to the difference in cooling rate for each part continues to exist even after the distortion point and disappears after the end of cooling.

In section A of step 3 of FIG. 3, the intermolecular rearrangement of the glass is eliminated and becomes a completely solid state, thereby temporarily stopping cooling or minimizing the cooling rate in order to prevent breakage due to accumulated transient distortion from the quenching process. If the glass is thermally stabilized through this temperature operation, it is cooled to room temperature within a range where no breakage occurs.

As such, the panel 10 according to the present invention, which has undergone each step, has a curved shape different from the conventional temperature of the glass as shown in FIG. 4. That is, in the conventional method, while forming a gentle curve, the curve of the present invention has a temperature section of quenching and quenching. As such, in the case of the panel 10 which has been subjected to each step of the present invention, for example, 29FCD, the surface of each part is changed in temperature as shown in FIG. 5.

Thus, in the present invention, the first step of compressing the panel 10 and then quenching the panel 10 to a temperature region where at least a portion of the molecules constituting the panel 10 cannot be rearranged; Re-heating the quenched panel 10 to a temperature above the ANNEALING POINT to maintain a certain period of time to completely remove the distortion, so that at least a portion of the molecules constituting the panel 10 cannot be rearranged. The third step of quenching to a predetermined lower point temperature (STRAIN POINT) and the fourth step of cooling the panel 10 at which the intermolecular rearrangement is completed by rapid quenching at a speed such that no breakage due to transient distortion occurs. It not only increases the mechanical strength but also minimizes the occurrence of planar stress, thereby improving thermal stability in the manufacturing process of cathode ray tube and minimizing compaction to reduce mislanding. One is able to provide a cathode-ray tubes panel 10 to.

As described above, according to the present invention, not only can the mechanical strength be increased, but also the occurrence of planar stress can be minimized, thereby improving thermal stability and minimizing compaction in the manufacturing process of the cathode ray tube. Provided is a method for producing a cathode ray tube panel which can be reduced.

Claims (4)

Compressing the panel and then quenching the panel to a temperature region where at least a portion of the molecules constituting the panel cannot be rearranged; Reheating the quenched panel to a temperature above the ANNEALING POINT and maintaining it for a period of time to completely remove the dwarf; Quenching at least a portion of the molecules constituting the panel to a predetermined lower point (STRAIN POINT) such that rearrangement is not possible; And cooling the panel after the intermolecular rearrangement by rapid quenching at a speed such that breakage due to transient distortion does not occur. The method of claim 1, Reheating the panel to a temperature above the slow cooling point, the method for producing a cathode ray tube panel, characterized in that it has a temperature range of at least 5 ℃ to 20 ℃ or more higher than a predetermined slow cooling point. The method of claim 1, The step of maintaining the panel at a temperature above the slow cooling point for a predetermined time, at least 10 minutes or more, the method for producing a cathode ray tube panel. The method of claim 1, The step of quenching to a predetermined lower limit temperature such that the highest temperature in the panel to rearrange the intermolecular is by the cooling air.