RU2070749C1 - Method for manufacturing face glass plate of gaseous-discharge display panel - Google Patents

Abstract

FIELD: electronic engineering; gaseous-discharge display devices. SUBSTANCE: prior to applying antiflash coating on lining plate of gaseous-discharge display panel, this plate is heated to 30-100 C, covered with continuous layer of silicic solution sol stabilized by lithium hydroxide with silicon oxide ((SiO₂)) concentration of 0.5 to 15 volume percent and modulus of 1 to 30; solution is sprayed from nozzle under definite process conditions. EFFECT: simplified procedure. 2 cl, 4 dwg

Description

 The invention relates to the field of electronic technology and can be used in the manufacture of gas discharge display panels (GUI).

 A known method of manufacturing the front fiberglass of the GUI, including glass harvesting operations, degreasing and applying anti-reflective coatings in the form of longitudinal and transverse stripes located between the display elements.

In the known method, anti-reflective coating is applied by screen printing on the outer surface of the front fiberglass plate in the form of a pattern of longitudinal and transverse opaque bands located between the indicator elements. After coating, it is dried in air at a temperature of at least 120 ^o C, and then burned at temperatures up to 470 ^o C. The disadvantages of this method include the technical complexity of the process, due to the need to use complex and high-precision equipment (for the manufacture of photomasks, stencils, printing ), high complexity and low yield.

The closest method of the same purpose to the claimed technical solution according to the totality of features is the method of manufacturing a glass plate, degreasing, applying an anti-reflective coating to the outer surface of the front glass plate in the form of strokes formed by the thick-film technology, drying it at a temperature of 120 150 ^o C, s subsequent sintering at a temperature of 470 ^o C (see technical specifications for gas-discharge sign-synthesizing graphic indicators IGG-64 * 64 ASHPK. 433.210.020.TU. Plate ЩФ7. 358.153, ЩФ7. 353.153MKK).

In the known technical solution, after manufacturing glass plates with the required geometry and accuracy, removing mechanical and greasy contaminants (degreasing), an anti-reflective paste coating is applied to the external surface of the front plate by screen printing in the form of individual strips (strokes) of length and width (0.4 ± 0.05) • (0.17 ± 0.03) mm, then dried in air at a temperature of 120-150 ^o C and sintered at a temperature of 470 ± 10 ^o C. During sintering, the organic part of the paste burns out, and the low-melting glass included in the composition of the paste, melts and firmly sts powder particles with the surface of the glass plate and with each other. The antiglare surface parameters of the glass plate are determined by the area of the opaque coating. The disadvantages of this method include the following:
the technical complexity of the process, due to the high accuracy of the formation of anti-glare elements and the need to manufacture technological equipment (photo templates, stencils, printing, etc.);
low quality of the coating (anti-glare elements are heterogeneous in geometry, color, etc.), which determines the appearance of the indicator and affects the uniformity and uniformity of the glow of the indicator elements along the screen field;
low yield of products.

 The aim of the present invention is to improve the quality of the anti-reflective coating, reducing the complexity and increasing the yield of products.

This goal is achieved by the fact that in the known method of manufacturing the front glass plate of a gas discharge indicator panel, including the manufacture of a glass plate, degreasing, applying an anti-reflective coating to the outer surface of the glass plate with its subsequent drying and high-temperature processing, coating to increase the brightness and contrast of the indicator cells on the inner surface of the glass plate before applying the anti-reflective coating, the glass plate is heated to a temperature of 30-100 ^o C, and anti-reflective e coating is applied with a continuous spraying layer of a solution of silica sol stabilized with lithium hydroxide with a concentration of silicon oxide (SiO ₂ ) from 0.5 to 15 vol. and a module from 1 to 30, while spraying the sol solution is carried out with a spray gun with a nozzle diameter of 0.2 to 2.5 mm at a compressed air pressure of 1.5 to 4.0 atm, with the nozzle at a distance of 200-600 mm from the external the surface of the glass plate, drying is carried out at a temperature of from 30 ^o C to 100 ^o C, and high-temperature processing is carried out at a temperature of 400-500 ^o C.

 When the GUI operates in conditions of increased external illumination, glare is formed on the mirror surface of the upper dielectric plate (front fiberglass), which cause operator eye fatigue and reduce the reliability of reading information. To eliminate this drawback, a special anti-reflective (rough) coating is formed on the outer surface of the upper dielectric plate of the ISU, which reduces the brightness of the light flux reflected from an external source by the outer surface of the upper dielectric plate. However, the presence of anti-reflective coating leads to diffusion scattering of light coming from the indicator cell. This disadvantage is eliminated by choosing the roughness of the anti-reflective coating (which should minimize the brightness of the reflected light and the amount of diffusion scattering of light coming from the design of the indicator cell, and provide the required resolution of the GUI) and using coatings on the inner surface of the upper dielectric plate to increase the brightness and contrast of indicator cells (for example, a lightproof coating in the form of a picture). With a very small roughness value (less than 0.01 μm), the effect of light scattering from an external source is practically absent, there is a mirror reflection, it is difficult to read information under external illumination. With a very large roughness (more than 100 μm), radiation from an external source is almost completely scattered, but the fiberglass has low transparency, the edge of the indicator element is fuzzy, blurry, i.e., there are large losses of brightness and contrast of the indicator element. Therefore, with an increase in roughness, the scattering power of light from the indicator element increases, the clarity (contrast) of the image deteriorates. To increase the clarity (contrast), an opaque dielectric coating is applied in the form of a pattern on the inner surface of the upper dielectric plate, while the sections of the plate not containing the specified coating (transparent sections of the plate) are located respectively above the indicator cells. The creation of the required roughness is ensured by the appropriate selection of anti-reflective coating application modes, i.e. anti-reflective coating technology.

 The analysis of the prior art, including a search by patent and scientific and technical sources of information and identification of sources containing information about analogues of the claimed invention, allows us to establish that the applicant has not found technical solutions characterized by features identical to all the essential features of the claimed invention. The definition from the list of identified analogues of the prototype made it possible to identify a set of essential (with respect to the technical result perceived by the applicant) distinctive features in the claimed object set forth in the claims.

 Therefore, the claimed invention meets the requirement of "novelty" under applicable law.

 Information about the fame of the distinguishing features in the totality of the characteristics of the known technical solutions with the achievement of the same as the claimed device, there is no positive effect. Based on this, it was concluded that the proposed solution meets the criterion of "inventive step".

 A method of manufacturing a front glass plate of a gas discharge indicator plate is as follows.

Anti-reflective coating is applied by spraying on the outer surface of the dielectric fiberglass in the form of a continuous layer. The surface of such a layer has a controlled roughness and provides a reduction in glare due to the scattering of incident light from an external source. The coating is formed from a sol of silicic acid containing SiO ₂ particles _of various sizes from 5 to 100-150 microns, by depositing these particles on a glass plate preheated to a temperature of 30-100 ^o C, forming a relief (rough) structure of a certain thickness. The roughness value, structure and thickness of the coating are determined by the formulation of the working solution, application modes and temperature treatment conditions.

A silica sol is obtained by dialysis or by passing a potassium silicate solution through ion exchange resins. Silicic acid is polymerized in an acidic environment; lithium hydroxide is introduced to stabilize it. In this case, H ⁺ cations are replaced by Li ⁺ cations, which passes into the diffusion layer, and the sol is negatively charged. A stabilized sol should be distinguished from a solution of lithium silicate, these are states of the same substance. The latter is a substance that is soluble in water, and the first is SiO ₂ particles ranging in size from 5 to 100-150 microns in a solution of lithium hydroxide. The optimal amount of stabilizer is selected experimentally. The ratio of SiO ₂ : Li ₂ O is called the module and with the ratio of SiO ₂ : Li ₂ O 1: 1 the module is 1, and with a ratio of 30: 1 the module is 30. When the module is changed, the density of the solution changes, for example: for module 2, the density is 1.041 g / cm, for module 20, the density is 1.022 g / cm, and the viscosity, respectively, is 13.1 sst and 15 sst. A change in the concentration of SiO ₂ affects the size of the roughness, which in turn changes the reflection coefficient. With an increase in SiO ₂ concentration, the roughness size increases, the reflection coefficient decreases, and, conversely, with a decrease in SiO ₂ concentration, the roughness decreases, and the reflection coefficient increases. Therefore, by changing the concentration of SiO ₂ , you can control the reflection coefficient. The concentration of SiO ₂ should be from 0.5 to 15 volume. At a concentration of less than 0.5 volume. the reflection coefficient is very large and approaches a mirror surface, the effect of anti-reflective coating is absent. At a concentration of more than 15 volume. the reflection coefficient is practically equal to "0", but due to the scattering of light from the indicator element in the anti-reflective layer, the indicator element has a blurred and increased size, the edge is fuzzy, a loss of resolution is observed.

 An anti-reflective coating is formed by spraying through a nozzle with a diameter of 0.2 mm to 2.5 mm, with a compressed air pressure of 1.5 atm to 4.0 atm. At a pressure of less than 1.5 atm, the coating layer has a "raw" appearance, there are smudges. The jet of the working solution escaping from the nozzle has large droplets and a small torch, which results in a coarse, coarse-grained surface, the roughness of which exceeds 100 microns. At a pressure of more than 4.0 atm, the spray jet is very finely dispersed, the torch is large, the coating is “dry”, due to the poor wettability of the glass surface, the adhesion of the coating is deteriorated.

 With a nozzle diameter of less than 0.2 mm and a minimum pressure of compressed air, the jet is very “dry”, adhesion and coating quality are unsatisfactory, an increase in diameter of more than 2.5 mm with a maximum air pressure leads to a very rough jet, the coating is inhomogeneous, smudges form .

 The distance from the nozzle to the substrate should be between 200 and 600 mm. With decreasing distance (less than 200 mm), the jet of the working solution with high pressure strikes the surface of the fiberglass, the coating has smudges, the unevenness of the applied layer in thickness. With increasing distance (more than 600 mm), the pressure of the working solution stream at the surface of the glass plate decreases, the coating is coarse, coarse-grained with poor diffusion.

Of great importance on the quality of the anti-reflective coating is the temperature of the glass plate during coating. The coating has high adhesion in the case when a particle (drop) of the working solution, in contact with the heated surface, spreads and moistens it, forming a uniform film, followed by evaporation of water from it. Evaporation of water should occur before spraying the solution during the subsequent passage of the atomizer and, therefore, a subsequent portion of the solution should lie on a dry or slightly damp surface. When lowering the temperature t ₁ less than 30 ^o C, the water does not have time to evaporate and the next portion of the solution falls on the "wet" coating, forming smudges and inhomogeneity of the layer. With an increase in t _1, water from the droplets of the working solution evaporates quickly and they do not have time to spread and form a uniform, even coating. The surface has a high roughness, there is a loss of contrast, resolution, information capacity, etc. coating adhesion is deteriorating.

After coating, it is dried. The temperature t ₂ drying is selected experimentally. The criterion of optimality of the selected mode is the adhesion and mechanical strength of the applied coating with fiberglass. With a decrease in temperature t ₂ (less than 30 ^o C), the mechanical strength of the coating is not high and the coating is easily destroyed by mechanical action on it, adhesion to the glass substrate is unsatisfactory. Heat treatment increases mechanical strength, adhesion and ensures complete removal of water particles from the coating. At a temperature of t ₂ above 100 ^o C, a change in the anti-reflective coating is practically not observed, therefore, a further increase in the temperature of t ₂ does not lead to an improvement in the coating parameters.

After drying the coating, annealing is carried out at t ₃ = 400-500 ^o C. During annealing, the anti-reflective coating acquires high mechanical strength due to compaction, and the optical and physical characteristics of the film are stabilized. At a temperature of t ₃ less than 400 ^o C and more than 500 ^o C, the coating has lower mechanical strength, with an increase in temperature t ₃ (ranging from 400 ^o C to 500 ^o C) the mechanical properties of the coating increase, hardening and stabilization of its properties (uniformity and optical density). Increasing the temperature t ₃ more than 500 ^o C leads to deterioration of the properties, the optical density increases, the coating becomes more fragile. Due to the fact that the coating is applied in the form of a continuous layer, its labor intensity is low.

For example, an anti-reflective coating was applied to the surface of a flat glass measuring 191x191x3 mm by spraying. The technological process of coating formation consists of the following operations:
preparation of a working solution of a sol of silicic acid stabilized with lithium hydroxide;
chemical cleaning of glass;
heating glass and spraying sol by spraying;
preliminary drying of the coating;
coating annealing.

The working solution is prepared from commercially available lithium-containing sol of silicic acid with a content of SiO ₂ 17 volume. by diluting it with water to a module of 4, the concentration of SiO ₂ being about 1.5 volume. The glass plate is cleaned in a washing solution containing trisodium phosphate-calcined soda and a surfactant at a temperature of 45 ± 5 ^o C, followed by washing in an ultrasonic bath in deionized water. The silicic acid sol is applied manually or semi-automatically from a spray gun at a compressed air pressure of about 3 atm, and the distance between the spray nozzle and the outer surface of the glass plate is about 250 mm. The glass plate before coating is heated to a temperature of t ₁ = 50-70 ^o C. After the coating is formed, the glass plate is dried in an oven at a temperature of t ₂ = 90 + 10 ^o C, for 60 minutes, then in a conveyor oven at a temperature of 470 + 10 ^o C for 30 minutes

The coating has the following parameters:
light transmission coefficient of 85%
reflection coefficient not more than 13%
98% yield
the complexity of applying anti-reflective coatings is about 0.5 n / h.

 After applying an antiglare coating to the outer surface of the fiberglass plate, coatings are applied to its inner surface (opaque coating or phosphor coatings in combination with an opaque coating) to increase the brightness and contrast of the indicator cells using known technologies.

 Possible GUI designs with a front fiberglass made according to the proposed method are shown in FIG. 1.3.

 The gas-discharge indicator panel (Fig. 1) contains an upper dielectric plate 1 (front glass plate) with an anti-reflective coating 2 on the outside, made in the form of a continuous translucent layer with a roughness of 0.01 to 100 μm, and a lower dielectric plate 3 with dividing barriers 4 , a system of orthogonal electrodes (anodes 5 and cathodes 6) forming closed volumes at the intersections (indicator cells), and phosphor elements 7. On the inner surface of the upper dielectric plate 1 further comprises I svetoneprozrachnoe coating 8 in a pattern (in particular, a matrix of FIG. 2) located respectively above separating barriers 4 lower dielectric plate 3, wherein portions of the inner surface of the upper insulating plate 1 not containing svetoneprozrachnogo cover 8, located above the indicator cells. The pattern of opaque coating 8 can be arbitrary (symbols, squares, triangles, etc.), but its dimensions must correspond to certain ratios.

 The gas discharge indicator panel in FIG. 3 contains an upper dielectric plate 1, on the inner surface of which there are phosphor elements 2, and a lower dielectric plate 3 with dividing barriers 4, a system of orthogonal electrodes 5 (anodes) and 6 (cathodes), which form indicator cells at the intersections, to the bottom of the indicator cells of the lower dielectric plate 3 installed additional phosphor elements 7, the outer surface of the upper dielectric plate 1 is provided with an anti-reflective coating 8, made in the form of a continuous translucent layer with a roughness of from 0.01 μm to 100 μm, the inner surface of the upper dielectric plate 1 with phosphor elements 2 is provided with an opaque coating 9 (in the form of a matrix of Fig. 4), while the specified opaque coating 9 and the phosphor elements 2 are made in the form of patterns, respectively above the separation barriers 4 and indicator cells of the lower dielectric plate 2.

 The principle of operation of these indicator panels is as follows: to output information between the anode and cathode, voltage is applied above the discharge voltage in the indicator cells, a breakdown of the gas gap occurs, after which the voltage on the cells decreases to the voltage to maintain the gas discharge. The ultraviolet radiation of the discharge excites the phosphor elements, providing their glow. As a result, the total brightness of the luminophore elements and the gas discharge is perceived.

 The size of the GUI indicator cell depends on the design of the GUI and can be from 0.1 mm to 10 mm or more. Hence the difference in surface roughness requirements. It should provide external contrast, the resolution of the display elements and the operation of the GUI in high ambient light. When the roughness of the outer surface of the dielectric plate is less than 0.01 μm, the surface has a high reflectivity and there is no scattering effect. With a roughness of more than 100 μm, the indicator cells have a low contrast, the edge of the indicator element becomes fuzzy, blurred, the perception and readability of information deteriorates. Roughness boundaries are determined experimentally and cover structurally possible ISUs (with different information capacities).

Devices (Fig. 1, Fig. 3), made using the front glass plates of the invention, have a brightness of 140-160 cd / sqm (in green) and good readability of information with an external illumination of 2000 lux. Similar devices with fiberglass plates (light transmission coefficients of about 50% reflection of about 48%), manufactured by the known method, had a green brightness of 100-120 cd / sqm and satisfactory readability of information in ambient light up to 500 lux. The complexity of the formation of antiglare coating according to the known method is-1.5 n / h, and the yield is 90%
Thus, the quality of the front glass plates (light transmittance and reflection, yield), made in accordance with the proposed method is significantly higher than that of the plates made by the known method, and the complexity is lower.

The above information about the alleged invention when using it allows you to get the following positive results:
the claimed invention is intended for use in industry, in the production of gas discharge display panels;
when using this invention, the laboriousness of forming an anti-reflective coating is reduced by 3 times and the yield is up to 98%, while gas-discharge display panels have a reflection coefficient from the front surface 6 times less than in the known technical solution, which allows the use of indicators for operation in high illumination.

 Therefore, the claimed invention meets the requirement of "industrial applicability" under applicable law.

Claims (2)

1. A method of manufacturing a front glass plate of a gas discharge indicator panel, including the manufacture of a glass plate, degreasing, applying an anti-reflective coating to the outer surface of the glass plate, followed by drying and high-temperature processing and coating to increase the brightness and contrast of the indicator cells on the inner surface of the glass plate, characterized in that before by applying an anti-reflective coating, the fiberglass plate is heated to 30 100 ^o C, and the anti-reflective coating is applied with a continuous layer of by spraying a solution of silicic acid sol with a particle size range of silicic acid sol 5,150 μm stabilized with lithium hydroxide with a concentration of silicon oxide of 0.5 to 15.0 vol. and module 1 - 30, while drying is carried out at 30 100 ^o C, and high-temperature processing is carried out at 400 500 ^o C to obtain a layer of anti-reflective coating with a roughness of 0.01 to 100.0 μm.  2. The method according to claim 1, characterized in that the spraying of the sol solution is carried out by a spray gun with a nozzle diameter of 0.2 2.5 mm at a compressed air pressure of 1.5 4.0 atm, positioning the nozzle at a distance of 200 600 mm from the outer surface of the glass plate .

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