KR19990003415A - Lightweight cathode ray tube - Google Patents

Abstract

The present invention relates to a lightweight cathode ray tube, and more particularly, to use a glass composition having a high X-ray absorption coefficient in order to reduce the thickness of the windshield in the cathode ray tube used for general televisions or monitors. In addition, the breakdown strength of the cathode ray tube windshield was increased by using the surface etching method. Also, in order to secure the lifetime of the cathode ray tube and the mechanical reliability of the scratch resistance to the environment, an oxide thin film and a polymer film were placed on the surface-etched windshield. The present invention relates to a lightweight cathode ray tube improved to maintain the above-described level of mechanical properties and X-ray absorptivity while reducing the thickness of the windshield by more than 20% by coating.

Description

Lightweight cathode ray tube

The present invention relates to a lightweight cathode ray tube, and more particularly, to use a glass composition having a high X-ray absorption coefficient in order to reduce the thickness of the windshield in the cathode ray tube used for general televisions or monitors. In addition, the breakdown strength of the cathode ray tube windshield was increased by using the surface etching method. Also, in order to secure the lifetime of the cathode ray tube and the mechanical reliability of the scratch resistance to the environment, an oxide thin film and a polymer film were placed on the surface-etched windshield. The present invention relates to a lightweight cathode ray tube improved to maintain the above-described level of mechanical properties and X-ray absorptivity while reducing the thickness of the windshield by more than 20% by coating.

Cathode ray tubes for general televisions and monitors maintain high vacuum by blocking the inside and the outside by three kinds of glass, the front glass on which the image is displayed, the rear glass to which the deflection coil is attached, and the neck glass into which the electron gun is inserted. In recent years, the cathode ray tube has become a trend of larger size, flattening and high resolution, in particular, the enlarged and flattened cathode ray tube requires greater glass strength than the conventional cathode ray tube. Of these, the windshield accounts for half of the total weight of the cathode ray tube, and if the thickness is increased to increase the strength at the time of enlargement and planarization, the weight increases not only rapidly but also decreases the productivity in the process of forming the glass and manufacturing the cathode ray tube. . Therefore, the manufacture of a lightweight cathode ray tube by reducing the thickness of the cathode ray tube windshield is a desired task of related industries.

Cathode ray tube glass must have the function of blocking the X-rays emitted when high energy electrons from the electron gun of the cathode ray tube collide with the shadow mask inside the cathode ray tube when the inside of the cathode ray tube is high vacuum and does not break even under the external constant impact. do. Therefore, in order to reduce the weight of the cathode ray tube glass, it is necessary to develop a technology that has a thin and sufficiently strong strength and a high X-ray absorption coefficient.

Until now, the method of increasing the strength of cathode ray tube has been a physical reinforcement method that gives compressive stress to the surface during cooling after shaping the windshield, a surface etching reinforcement method that removes defects on the glass surface, and Na + ions below the transition point of glass. Attempts have been made to strengthen cathode ray tube windshields by chemical strengthening methods of substitution with K + ions.

However, although these methods have been partially applied to partially enlarged or planarized cathode ray tube glass, the physical methods cannot obtain the sufficient strength required for complex shaped windshields, and the etching enhancement methods for ion exchange or surface defect removal. Silver cathode ray tube manufacturing process or final product is difficult to ensure the reliability of the external damage in actual use, it is necessary to have a very high protective film such as oxide coating protective film or polymer coating protective film to prevent this. In particular, not enough reinforcement technology has been developed to produce a lightweight cathode ray tube by reducing the thickness of the cathode ray tube glass, and when the thickness of the windshield becomes thinner by 5-10% or more, the amount of X-ray emission becomes larger than the allowable value. appear. Therefore, technologies and products that have significantly reduced the thickness of the cathode ray tube by reducing the thickness in response to the enlargement and planarization of the cathode ray tube have not been developed yet.

Therefore, the present invention is to reduce the thickness of the front glass of the cathode ray tube in order to improve the disadvantage that the glass weight becomes heavy due to the thick thickness of the glass at the time of the enlargement, planarization of the conventional cathode ray tube, while reducing the weight of the glass and mechanical strength and X-ray emission amount The objective is to provide a new lightweight cathode ray tube that maintains the suppression of the anode above the existing cathode ray tube level.

The present invention provides a cathode ray tube used for a television or a monitor, wherein the front glass of the cathode ray tube has an X-ray absorption coefficient of 34 cm ⁻¹ or more at 0.6 Å, and the glass surface is etched on the surface, and then an oxide thin film and a polymer film are sequentially It is characterized by being coated.

Hereinafter, the present invention will be described in more detail.

The present invention is to reduce the thickness of the front glass of the cathode ray tube used for general televisions or monitors to reduce the weight of the cathode ray tube to maintain the mechanical strength and X-ray emission level above the existing cathode ray tube, the center portion of the cathode ray tube front glass After manufacturing cathode ray tube whose thickness is reduced by more than 20%, the surface of the windshield is treated and surface defects are removed by surface etching method to increase the breaking strength of windshield by more than 3 times, and lower the breaking strength. In order to prevent development and external damage, after coating, the coating layer having an excellent hardness is formed by oxide coating or polymer film coating. In this case, the front glass used is a high X-ray absorption coefficient.

In general, cathode ray tubes used in televisions and monitors should have a strength corresponding to the pressure difference formed by the high vacuum applied to the inside. In particular, it is not simply the strength corresponding to the difference in atmospheric pressure (1 kg / cm ² ) applied to the cathode ray tube, but at a pressure difference of 3 kg / cm ² corresponding to three times the atmospheric pressure to ensure reliability in long-term use. No destruction should occur. Therefore, in general, in consideration of these conditions, when the cathode ray tube is manufactured, the tensile stress of the front glass surface is designed to be 80 kg / cm ² or less under 1 atm caused by the pressure difference between the inside and the outside of the cathode ray tube. The windshield is not broken when the pressure difference between inside and outside is 3 kg / cm ² . The tensile stress on the glass surface increases in inverse proportion to the square of the thickness of the windshield. Therefore, if the thickness of the windshield is reduced by 20%, a tensile stress of 80 kg / cm ² /(0.8) ^2, i.e. 125 kg / cm ² is formed under 1 atmosphere, and 45 kg / cm in order to make the design value 80 kg / cm ² or less. A compressive stress of ² is required, and considering the long-term reliability, a compressive stress of 3 x 45 kg / cm ² or 135 kg / cm ² is required under 3 atmospheres.

Therefore, the present invention compensates this by increasing the fracture strength value of the windshield by three times or more by the method of removing surface defects in order to obtain an element corresponding to a compressive stress of 135 kg / cm ² . In fact, after the surface etching, the cathode ray tube is subjected to several heating and cooling processes. In this case, the surface etching method is overcome by the surface coating of the front glass and the protective coating or the high hardness coating.

One of the important characteristics of the cathode ray tube's windshield is the blocking of X-rays generated when the electrons come out of the electron gun and the electrons accelerated to energy of several tens of kV collide with shadow masks, phosphors and glass. The allowance for X-rays is 5 mR / hour at the surface of the windshield center of the cathode ray tube. The amount of X-rays emitted is expressed by the following equation.

[Equation 1]

I = I _O exp (-μt)

Where I is the emission of X-rays passing through the windshield, I ₀ is the emission of initial X-rays, μ is the X-ray absorption coefficient, and t is the thickness of the windshield.

That is, as the thickness t becomes smaller, the X-ray absorption coefficient μ must be increased.

In the cathode ray tube used in conventional TVs, a front glass having a composition of 28 cm ⁻¹ at an X-ray absorption coefficient of 0.6 파장 is used. Glass having a high X-ray absorption coefficient has a high cost and low productivity, such as a projection TV. It has been used for special purposes.

Therefore, the present invention uses a high X-ray absorption glass of 34cm ^-1 or more at a wavelength of 0.6 엑스 to maintain the same level as the existing X-ray emission amount even if the thickness is thinner than 20%, the weight of the front glass In addition to compensating for the increasing defects of cost, the company has dramatically improved productivity as it is thinner and lighter. In particular, as the voltage applied to the electron gun increases as the size increases, the amount of BaO in the composition of the windshield is increased to increase the X-ray absorption ability at high voltage by 20% or more than the conventional glass. .

As such a cathode ray tube windshield having a high X-ray absorption coefficient, for example, 52 to 56 wt% SiO ₂ , 0.1 to 0.5 wt% Li ₂ O, Na ₂ O 6 to 8 wt%, and K ₂ O 6 to 8 wt% %, MgO 0.1-1 wt%, CaO 0.5-2 wt%, BaO 12-16 wt%, SrO 6-8 wt%, ZrO ₂ 2-4 wt%, TiO ₂ 0.3-0.7 wt%, CeO ₂ 0.3- Glass composed of 0.7% by weight, Al ₂ O ₃ 2.0 to 3.5% by weight, and Sb ₂ O ₃ 0.3 to 0.7% by weight can be used.

On the other hand, since the cathode ray tube should not be destroyed for a certain amount of external damage that may occur in actual use, it is tested with a sandpaper of # 150 and tested for destruction at 3 atm. In general, in the case of the glass produced by the surface etching method, if the virtual sandpaper of # 150 is given, the defects formed by the virtual work on the stress concentration, resulting in a significant decrease in strength.

Accordingly, in the present invention, in order to prevent such a decrease in strength, a thin film layer having a very high hardness is formed on the surface of the windshield to increase scratch resistance, and a reinforcement film is attached to the windshield of the cathode ray tube to prevent the cathode ray tube from external impact. In addition to preventing breakage, even if the destruction occurs by a certain impact or more to prevent the scattering of debris to improve safety.

According to the present invention, the surface etching method is applied as a method of strengthening the glass surface, an oxide coating is applied to compensate for the decrease in strength, and the polymer film is coated to restore the reliability against external impact.

In the present invention, the strengthening of the windshield by the surface etching method first cleans the glass surface and immerses it in the surface etching solution. At this time, in order to remove the interference effect of the etching by the reaction product formed during etching, the glass is removed at regular intervals, that is, 10 to 30 minutes, and washed with water to remove the reaction product, and then etched again in an etching bath. Do it. As the surface etching solution used for such etching, for example, a hydrofluoric acid solution, a mixed solution of hydrofluoric acid and sulfuric acid, or a mixed solution of hydrofluoric acid and hydrochloric acid is used, and the concentration of the solution is 10-20% by weight in consideration of the etching rate. It is preferable.

As such, the etching thickness of the glass surface after etching is 5 to 500 µm, and when the heat treatment process is performed in the same manner as in the manufacture of cathode ray tubes, the fracture strength value is 2 to 3 times higher than before the surface etching treatment. Indicates. However, for the purpose of 20% weight reduction, the surface etching alone cannot be used as a reinforcing method to reduce the weight of the front glass because it is insufficient only after the strength of 2 to 3 times after heat treatment. do.

According to the present invention, after surface etching, an oxide thin film is coated, for example, an oxide protective layer using at least one selected from SiO ₂ , ITO, SnO ₂ , ZrO ₂ , TiO ₂ , Y ₂ O _3, and Al ₂ O ₃ . On the glass surface etched by chemical vapor deposition or spray spraying.

At this time, since the deposited oxide thin film has a high hardness of 9H or more, by coating the oxide protective film on the surface-etched windshield, it is possible to prevent scratches caused by the cathode ray tube manufacturing process, and also due to moisture during heat treatment. The degradation phenomenon can be prevented.

In practice, the cathode ray tube must maintain a long life, so scratches generated in the actual environment are a very big problem. However, since the oxide coating film formed according to the present invention has a very thin thickness of 0.05 to 1 μm, it cannot have complete scratch resistance to the external environment. Therefore, in order to lighten the windshield, a very thick polymer film layer must be formed on the oxide coating film to increase scratch resistance.

In the present invention, in order to enhance the adhesion between the polymer layer and the windshield when strengthening the windshield by polymer film coating, pretreatment is performed by spraying a solution composed of silane, epoxy, water and a solvent before the polymer coating by a spray method. The polymer film layer is formed and then cured through a suitable heat treatment temperature and time.

According to the present invention, the pretreatment solution used herein may be used by mixing triethyleneetetramine (TETA), resin, silane, curing agent, and water of different compositions with a solvent such as methanol or acetone.

The polymer film used in the present invention may be made of, for example, a material selected from polyester, polycarbonate, polyvinyl chloride, polystyrene, acrylic, polystyrene, and urethane. It can attach by. The thickness of the polymer film attached in this way is formed in 5-500 micrometers, the heat processing temperature after film adhesion is 100-200 degreeC, and heat processing time shall be 10-60 minutes.

As a result, as a result of analyzing the hardness of the formed polymer film through a pencil test, it shows a very high film hardness value of 3H or more.

As described above, the windshield manufactured by applying the surface etching method, the oxide thin film coating, and the polymer film formation exhibits a value 10 times higher than that of the windshield before strengthening the fracture strength value. Therefore, in the case of manufacturing the cathode ray tube by lightening the windshield according to the present invention, even if the weight is reduced to 20% or more, sufficient mechanical reliability can be obtained and sufficient scratch resistance to external damage is actually obtained. It gives reliability for long life.

Hereinafter, the present invention will be described in detail by way of examples.

Example

Manufacture of windshield

In order to reduce the amount of X-ray emission while thinning the front glass of the cathode ray tube, the glass has a composition with higher X-ray absorption coefficient than the conventional glass, and the physical and chemical properties of the cathode ray tube are applied to the front glass of the cathode ray tube as shown in Table 1 below. 14 inches of windshield was manufactured by the conventional method by selecting the possible composition, but each was prepared in the following thicknesses (10% reduction, 20% reduction, 30% reduction).

[Table 1] (Unit: weight%)

division High X-ray absorption glass (Example) Existing composition SiO ₂ 54.0 61.0 Li ₂ O 0.3 0.1 Na ₂ O 7.0 7.3 K ₂ O 7.0 7.0 MgO 0.8 0.5 CaO 1.0 1.5 SrO 7.5 8.5 BaO 15.0 9.0 ZrO ₂ 3.0 2.0 TiO ₂ 0.4 0.4 CeO ₂ 0.6 0.3 Al ₂ O ₃ 3.0 2.0 Sb ₂ O ₃ 0.4 0.4 X-ray absorption coefficient (μ: 0.6Å) 34.2 28.3

The X-ray emission was measured at 40 kV for each of the windshields prepared in the Examples and the existing compositions, and the results are shown in Table 2 below.

As shown in the following Table 2, even if only 10% of the composition glass is thinned, the amount of X-ray emission is close to the regulated 0.5 mR / hr, and when the thickness is reduced by more than 20%, the X-ray emission far exceeds the regulated value. have. However, in the case of X-ray superabsorbent glass manufactured in Example, even if the thickness is 20% thinner than the existing thickness, the X-ray emission amount is maintained at or below the existing level, and even if the thickness is reduced to 30%, the regulation value is maintained at 0.5 mR / hr or less. Therefore, this means that the thickness of the windshield of the cathode ray tube can be reduced by 20% or more when using the composition of Example Table 1 according to the present invention.

Center glass thickness (Unit: ㎜) Existing composition glass (unit: mr / hour) Example Composition Glass (Unit: mr / hour) 13.5 0.25 0.04 12.15 (10% decrease) 0.45 0.10 10.8 (20% decrease) 1.02 0.22 9.45 (30% decrease) 1.89 0.40

[Reinforced front glass by surface etching method]

A 14-inch color television with high X-ray absorption composition was cut into 12cm × 2.5cm × 1cm with nichrome wire, and then a sample for breaking strength measurement was prepared.

The cut specimen was cleaned by using an ultrasonic cleaner, distilled water and a dryer. After preparing at least 10 liters of hydrofluoric acid solution, a mixed solution of hydrofluoric acid and hydrochloric acid, and a mixed solution of hydrofluoric acid and sulfuric acid, the solution was placed in a surface etching solution bath. In order to eliminate the interference effect of the etching by the reaction product formed during the etching, the stirrer made of Teflon was rotated at about 60 rpm during etching, and the samples were taken out every 15 minutes, washed with distilled water, and rubbed with a plastic material. After the removal, the specimen was reinserted into the etching bath to continue the reaction. The etched thickness was analyzed using a surface profiler (Tencor), the surface roughness before and after etching was measured by AFM (DI), the fracture strength was measured by three-point strength measurement, and the corrosion of the pin was analyzed using SEM.

The change in fracture strength with the etched thickness for each etching composition is shown in Table 3 below.

Etching thickness composition Initial state 10 μm 20 ㎛ 50 μm 100 μm 200 μm Hydrofluoric acid (10wt%) 7-8 kg / mm2 40-50 kg / mm2 70-80㎏ / ㎠ 120 to 150㎏ / ㎠ 120 to 150㎏ / ㎠ 120 to 150㎏ / ㎠ Hydrofluoric acid (15wt%) + hydrochloric acid (15wt%) 7-8 kg / mm2 30-40 kg / mm2 50 to 60 kg / mm2 80-100 kg / mm2 80-100 kg / mm2 80-100 kg / mm2 Hydrofluoric acid (15wt%) + sulfuric acid (15wt%) 7-8 kg / mm2 30-40 kg / mm2 50 to 60 kg / mm2 70-100 kg / mm2 70-100 kg / mm2 70-100 kg / mm2

After the surface of the windshield was immersed in sand solution of # 150 on the surface of the specimen which was etched by 20㎛ with the composition of each solution, the fracture strength was measured and the measurement result of the fracture strength after the heat treatment process as in the manufacture of cathode ray tube was as follows. Table 4 shows.

Etching thickness composition Initial state Virtual after After heat treatment Hydrofluoric acid (10wt%) 7-8 kg / mm2 4 to 6 kg / mm2 15 to 20 kg / mm2 Hydrofluoric acid (15wt%) + hydrochloric acid (15wt%) 7-8 kg / mm2 4 to 6 kg / mm2 10-18 kg / mm2 Hydrofluoric acid (15wt%) + sulfuric acid (15wt%) 7-8 kg / mm2 4 to 6 kg / mm2 15 to 18 kg / mm2

As shown in the above results, the surface etching method significantly lowered the breaking strength after virtualizing the surface of the windshield, but after the heat treatment, the breaking strength value was about 2 to 3 times higher than before the surface etching treatment. Therefore, it can be seen that the surface etching method alone cannot be used as a reinforcing method for reducing the weight of the front glass, but must be used in combination with a protective film coating method for preventing the decrease in strength.

[Reinforced Front Glass by Oxide Thin Film Coating Method]

An oxide protective film was prepared by chemical vapor deposition on a ------ condition using SiO ₂ with a specimen in which the surface of the windshield having a high X-ray absorption coefficient was etched 20 μm with a solution of hydrofluoric acid (10 wt%). The deposited oxide thin film was formed to a thickness of 0.2 ㎛, exhibited a high hardness of more than 9H.

[Reinforced Front Glass by Polymer Film Coating]

A polymer having a very high coefficient of thermal expansion compared to the windshield after depositing an oxide thin film with a thickness of 0.2 탆 for a specimen in which the surface of the windshield having a high X-ray absorption coefficient was etched with a solution of hydrofluoric acid (10 wt%) by 20 탆. The film was formed by the spray spray method. In order to improve the adhesion between the polymer layer and the windshield, a solution consisting of silane, epoxy, water, and a solvent was pretreated by spray spraying before the polymer coating. The solution used was prepared by mixing triethyleneetetramine (TETA), resin, silane, curing agent and water of different composition in methanol solvent. The polymer film used was a polyester film, the thickness was 50 micrometers, the heat processing temperature was 180 degreeC, and the heat processing time was 30 minutes.

The hardness of the formed polymer film was analyzed by a pencil test and showed a very high film hardness value of 3H or more.

The surface strength of the hydrofluoric acid (10 wt%), the formation of the oxide thin film and the formation of the polymer film layer were shown in Table 5 below.

Initial state Virtual after Hydrofluoric acid (10wt%) surface etching (20㎛) + silica thin film (0.1㎛) + polymer film (30㎛) 100-130 kg / mm2 80 to 100 kg / mm2

As described above, when the surface etching method, the oxide thin film, and the polymer film are formed, the surface of the windshield is imaginary, and its breaking strength value is viewed. The value was more than 10 times compared to-. Therefore, according to the present invention, even when manufacturing the cathode ray tube by reducing the weight of the front glass, sufficient mechanical reliability and scratch resistance were shown, so it was confirmed that the cathode ray tube was not only light in weight but also reliable in prolonging its life.

As described above, according to the present invention, when forming the front glass in the cathode ray tube manufacturing method, the X-ray absorption coefficient is used at the surface etching method of breakdown strength of the cathode ray tube front glass at the same time using glass having a specific composition of 34 cm ^-1 or more at 0.6 Å. In order to ensure the lifetime of the cathode ray tube and the mechanical reliability of the scratch resistance to the environment, the thickness of the windshield in the cathode ray tube manufacturing is coated by coating an oxide thin film and a polymer film on the surface-etched windshield. While reducing 20% or more, mechanical properties and X-ray absorption are also improved to maintain existing levels.

Claims (7)

In a cathode ray tube used for a television or a monitor, the front glass of the cathode ray tube has an X-ray absorption coefficient of 34 cm ⁻¹ or more at 0.6 Å, and the glass surface is surface-etched and then coated with an oxide thin film and a polymer film in order. Lightweight cathode ray tube, characterized in that. According to claim 1, wherein the composition of the front glass is SiO ₂ 52 to 56% by weight, Li ₂ O 0.1 to 0.5% by weight, Na ₂ O 6 to 8% by weight, K ₂ O 6 to 8% by weight, MgO 0.1 to 1 wt%, CaO 0.5-2 wt%, BaO 12-16 wt%, SrO 6-8 wt%, ZrO ₂ 2-4 wt%, TiO ₂ 0.3-0.7 wt%, CeO ₂ 0.3-0.7 wt%, Al ₂ O ₃ 2.0 ~ 3.5 wt% and Sb ₂ O ₃ 0.3 ~ 0.7 weight cathode ray tube, characterized in that the composition in the range of% by weight. 2. The lightweight cathode ray tube of claim 1, wherein the surface etching is etched using a hydrofluoric acid solution, a mixed solution of hydrofluoric acid and sulfuric acid, or a mixed solution of hydrofluoric acid and hydrochloric acid. The lightweight cathode ray tube of claim 1, wherein the oxide thin film is formed of at least one component selected from SiO ₂ , ITO, SnO ₂ , ZrO ₂ , TiO ₂ , Y ₂ O _3, and Al ₂ O ₃ . The lightweight cathode ray tube according to claim 1 or 4, wherein the oxide thin film is composed of a single layer and a multilayer, and has a thickness of 0.05 to 1 m. The lightweight cathode ray tube of claim 1, wherein the polymer film is made of a material selected from polyester, polycarbonate, polyvinyl chloride, polystyrene, acrylic, polystyrene, and urethane, and has a hardness of 3H or more. 7. The polymer film of claim 1 or 6, wherein the polymer film is formed by a spray spray method after pretreatment in which a solution composed of silane, epoxy, water and a solvent is sprayed prior to polymer coating, and is hardened by heat treatment. A lightweight cathode ray tube, characterized in that it is m.