Chunghwa Picture Tubes, Ltd.

Zenith Electronics Corporation

Chung Picture Tubes, Ltd.

Hua-Sou Tong

Chun-Min Hu

Yu-Chung Yu

Gregory T Prando

Wen-Chi Chen

Hao-Cheng Hung

Chung-Min Hu

Robert J Adler

Kuo-Chu Wang

Roland W Norris

Ming-Yu Hsu

Mi-Yui Hsu

A holder for maintaining an apertured shadow mask in fixed relation to the display screen of a color cathode ray tube (CRT) includes the combination of a mounting stud attached to an inner portion of the CRT's glass envelope and an apertured resilient metal holder attached to the shadow mask's peripheral frame and adapted to receive the mounting stud in a tight-fitting manner. A plurality of such mounting stud/metal holder combinations securely attach the top, bottom and lateral edges of the shadow mask frame to adjacent inner portions of the CRT's glass envelope adjacent its display screen. Heating of the shadow mask caused by the CRT's electron beams incident thereon gives rise to heating and thermal expansion of the shadow mask metal holders. Thermal expansion of the metal holders causes the shadow mask to rotate about the CRT's central axis resulting in a shift of the shadow mask apertures with respect to video image-producing phosphor deposits on the display screen's inner surface which degrades video image color purity. To prevent misalignment of the shadow mask apertures with the phosphor deposits caused by shadow mask holder thermal expansion, the shadow mask holders are formed from a material having a low coefficient of thermal expansion which maintains the shadow mask and its apertures in a fixed, predetermined location and orientation during CRT operation. The shadow mask holders are preferably comprised of a material having a coefficient of thermal expansion of less than 2.0.times.10.sup.-6 cm/cm/.degree. C. such as, for example, Invar, Neovar or Kovar.

Thermal expansion for color CRT

An arrangement for mounting a shadow mask, or color selection electrode, in the glass envelope of a color cathode ray tube (CRT) includes four resilient metal holders, each spot welded to a respective upper, lower or lateral portion of the shadow mask's skirt. Each holder is formed from a unitary metal strip which is shaped so as to include an inner mounting portion spot welded to the mask's skirt and an outer apertured portion adapted to receive a stud attached to and extending inwardly from the CRT's glass envelope. The shadow mask undergoes thermal deformation, or doming, when heated by electron beams incident thereon and transfers heat to each of the metallic holders. Each of the metallic holders, in turn, undergoes thermal deformation, but because of the shape and orientation of the holders relative to the shadow mask, the four holders deflect the shadow mask in a direction generally perpendicular to and outward from the CRT's glass display screen, i.e., along the CRT's Z-axis. By deflecting the thermally deformed shadow mask along the CRT's Z-axis, alignment between the mask's beam passing apertures and phosphor deposits on the CRT's display screen is maintained and video image color purity is not degraded.

Shadow mask mounting arrangement for color CRT

A high molecular weight, i.e., molecular weight of 90,000-750,000, conductive polymer soluble in both water and alcohol is mixed with a solution of water, alcohol, tetraethoxysilane (TES), and nitric acid (HNO.sub.3) to provide an antistatic coating for a glass display panel of a cathode ray tube (CRT) for grounding static charge on the panel. Conductive polymers such as of polyaniline mixed with either polystyrene sulfonic acid or polyacrylic acid in a molecular ratio of 1:1 or 3,4 polyethylenedioxythiophene added to polystyrenesulphonate in a molecular ratio of 1:1 form a conductive complex which when mixed with a solution of water, alcohol, TES and HNO.sub.3 provides a coating solution with a resistivity in the range of 10.sup.7-10.sup.9 ohm/cm.sup.2 on the outer surface of the CRT display panel.

Polymeric antistatic coating for cathode ray tubes

The inner surface of a video display panel such as cathode ray tube (CRT) glass faceplate is initially coated with a mixture of one of the primary color phosphors, an organic binder such as polyvinyl alcohol (PVA) diluted with water, and a photoresist agent. The organic binder overcomes the poor adhesion to the glass faceplate of the photoresist which typically includes polyvinyl pyrrolidone (PVP) and reduces the oxygen which decreases phosphor exposure time. To overcome PVA and PVP incompatibilities which give rise to nonuniform film thickness, a vinyl pyrrolidone-vinyl alcohol (VP-VA) copolymer is added to the phosphor, organic binder and photoresist mixture in the range of 0.1-30 wt %. The copolymer with both the VP and VA functioning groups serves as a coupling agent between the PVA and PVP and eliminates incompatibilities between these components. The VP-VA copolymer preferably has a VP/VA mole ratio in the range of 20/80 to 80/20. The photoresist further includes a photosensitive tetraalkylammonium salt and water. By substituting the sodium disulfonate group in the prior an disodium salt with a di-tetraalkylammonium group, the water solubility of the salt is substantially increased permitting increased concentrations of the tetraalkylammonium salt to be used in the photoresist for improved video image contrast. The tetraalkylammonium salt also serves as a linking, or bonding, agent between VP-VA and PVP to prevent the VP-VA from being wiped away during CRT manufacture and for improved application of the photoresist to the glass faceplate.

Photoresist for cathode ray tubes that includes vinyl

Apparatus for applying an antistatic and/or antireflective coating to the outer surface of a curved glass display screen of a cathode ray tube (CRT) includes a spin coating arrangement for rotating the CRT about its longitudinal axis after the coating solution is deposited on a center portion of the display screen. Centrifugal force and gravity urge the coating solution outwardly toward the edges of the display screen in forming a thin layer of uniform thickness on the display screen. A curved shield shaped in accordance with the display screen's curvature is disposed above the display screen in closely spaced relation thereto to form a chamber of stable air above the display screen and eliminate air turbulence and its tendency to spread the coating nonuniformly. The curved shield may include a center aperture for permitting the coating solution to be deposited upon the display screen prior to rotation and is adapted for easy attachment to and removal from the CRT's peripheral implosion protection band.

Apparatus for improved coating of a CRT display screen

For use on the outer surface of a faceplate of a display device such as of the cathode ray tube (CRT) type, a first inner antistatic layer of Sb--SnO.sub.2 (particle size between 5-20 nm) is applied to a thickness in the range of 200-600 nm. The Sb--SnO.sub.2 layer has a high light refractive index (n.sub.1 =1.8) and also provides an antireflection function. After pre-heating the faceplate to a temperature in the range of 35.degree.-50.degree. C., a second intermediate antireflection layer of colloidal TiO.sub.2 (light refractive index n.sub.2 =2.0 and particle size between 5-50 nm) is applied over the first inner layer to a thickness of 100-200 nm. A third outer antireflection layer is then applied over the intermediate layer in the form of a silica gel coating at a temperature in the range of 35.degree.-45.degree. C. with a thickness in the range of 100-200 nm and a light refractive index n.sub.3. The second and third antireflective layers follow the 1/4 wavelength rule, where n.sub.3 .perspectiveto..sqroot.n.sub.2 . The multilayer antireflective coating may also be employed in a five layer coating, where the TiO.sub.2 and silica gel layers are repeated in proceeding outward from the glass substrate to provide a wideband antireflection capability.

Multilayer antistatic/antireflective coating for display device

A multilayer antireflective coating is applied to the outer surface of a video display panel such as a cathode ray tube (CRT) or a flat panel display in the form of successive thin layers each having a different light refractive index, where the light refractive index of each layer decreases in the direction away from the surface of the display panel and toward the outer layer of the coating. Each layer is formed from the same starting gel materials, with the degree of crosslinking of each gel layer varied to provide the desired light refractive index for reducing reflections from the display panel's outer surface over a wide spectrum. The extent of crosslinking and thus the individual layer's light refractive index is varied by controlling the aging of the gel, with longer aging providing increased crosslinking and larger molecular weight for a lower light refractive index. For example, silica gels aged over different time periods provide gels having a light refractive index ranging from 1.45 (shorter aging) to 1.18 (longer aging).

Multilayer antireflective coating for video display panel

An antistatic coating for the outer surface of a video display panel such as of a cathode ray tube (CRT), and a method of applying this type of surface coating, employs a conventional antistatic material such as antimony doped tin oxide to which is added a solvent which is (1) soluble in water and alcohol, (2) has an evaporation point higher than that of water, and (3) has greater solubility for oil-based contaminants than for water. Solvents having these characteristics and which are adapted for use in the antistatic coating include ethylene glycol and dimethyl-based solvents, and their derivatives. The antistatic coating has reduced susceptibility to picking up surface contaminants such as dust and wiping residues such as applied in cleaning the display panel, particularly during manufacture, while affording a high degree of static charge dissipation.

Antistatic coating for video display screen

The outer surface of the glass display panel of a cathode ray tube (CRT) is first coated with an antistatic conductive metal salt solution. A water or organic solvent soluble antireflective coating is then applied by conventional means such as spinning, spraying or dipping to the glass display panel over the first coating. The antireflective coating is comprised of either an organic or an inorganic salt, or a polymer. The coated display panel is then baked, followed by thorough washing with either water in the case of an organic or inorganic salt or water soluble polymer antireflective coating, or toluene in the case of a non-water soluble polymer antireflective coating. Washing the display panel partially dissolves the salt or polymer in the antireflective coating more on the outer surface of the coating than on the inner portion of the coat adjacent the glass facelate. Dissolution of a portion of the salt or polymer in the coating produces pores in the coating and variations in coating thickness, thus changing the light refractive index of the coating. A continuous decreasing dissolution rate determined by the extent of washing of the coated display panel provides the coating with a continuous decreasing light refractive index and broadband antireflection (400-700 nm) with a minimum reflectance of 1.0% in the range of 560-650 nm. Knowing the light refractive index of the glass substrate and that of air (typically 1.0), the refractive index of the salt or polymer coating may be established by the extent of dissolution of the coating during washing.

Broadband antireflective and antistatic coating for CRT

An apparatus and method for forming color video display screens of the line or stripe screen type are disclosed. Tubules form menisci of screen element liquids which are contacted with a moving display screen surface to produce screen element lines comprising the screen.

Meniscus coating of CRT screens

The inner surface of a video display panel such as cathode ray tube (CRT) glass faceplate is initially coated with a mixture of one of the primary color phosphors, an organic binder such as polyvinyl alcohol (PVA) diluted with water, and a photoresist agent. The organic binder overcomes the poor adhesion to the glass faceplate of the photoresist which typically includes polyvinyl pyrrolidone (PVP) and reduces the oxygen which decreases phosphor exposure time. To overcome PVA and PVP incompatibilities which give rise to nonuniform film thickness, a vinyl pyrrolidone-vinyl alcohol (VP-VA) copolymer is added to the phosphor, organic binder and photoresist mixture in the range of 0.1-30 wt %. The copolymer with both the VP and VA functioning groups serves as a coupling agent between the PVA and PVP and eliminates incompatibilities between these components. The VP-VA copolymer preferably has a VP/VA mole ratio in the range of 20/80 to 80/20.

Photoresist for cathode ray tubes

A multilayer antireflective coating is applied to the outer surface of a video display panel such as a cathode ray tube (CRT) or a flat panel display in the form of successive thin layers each having a different light refractive index, where the light refractive index of each layer decreases in the direction away from the surface of the display panel and toward the outer layer of the coating. Each layer is formed from the same starting gel materials, with the degree of crosslinking of each gel layer varied to provide the desired light refractive index for reducing reflections from the display panel's outer surface over a wide spectrum. The extent of crosslinking and thus the individual layer's light refractive index is varied by controlling the aging of the gel, with longer aging providing increased crosslinking and larger molecular weight for a lower light refractive index. For example, silica gels aged over different time periods provide gels having a light refractive index ranging from 1.45 (shorter aging) to 1.18 (longer aging). An antistatic layer may be applied directly to the outer surface of the display panel before the antireflective coating is applied by adding an electrically conductive fine powder such as of tin oxide, antimony-doped tin oxide, etc. The high light refractive index of these conductive coatings, i.e., n&gt;1.8, further improves the antireflective characteristics of the multilayer coating.

For use in a self-emitting color display device such as a cathode ray tube (CRT) having a display screen with a phosphor coating on its inner surface, a surface coating disposed on the display screen's outer surface affords improved color purity, or contrast, by reducing overlap in the color spectrum between two adjacent primary colors, i.e., between red and green and/or between green and blue. An organic dye is added to either an inner antistatic layer or an outer antireflective layer of an antireflective/antistatic outer coating on the display screen, where both of the aforementioned layers contain silane. The dye functions as a color filter absorbing only light within the frequency range between adjacent primary colors, such as between the red and green color phosphors, i.e., in the range of 460-500 nm, and/or between the green and blue color phosphors, i.e., in the range of 560-600 nm. A silane coupling agent is also added to serve as a binding agent bridging the organic dye and silane together. In this manner, the organic dye is bonded to the silane in either the antistatic layer or the antireflective layer to prevent separation and escape of the organic dye filter from either of these layers of the outer coating on the display screen.

Surface coating with enhanced color contrast for video display

A damping arrangement for use with a shadow mask in a color cathode ray tube (CRT) absorbs vibrations of the shadow mask, particularly at low frequencies, to maintain registration of the shadow mask apertures with phosphor deposits on the inner surface of the CRT's faceplate for high video image color purity. A damping material having a higher modulus of elasticity (Young's modulus) than that of the shadow mask is applied to one or both surfaces of the shadow mask either over the entire surface or in spaced bands extending the length or width of the mask. The damping coating may be applied either by spraying or by vacuum deposition and may be comprised of virtually any material having a higher modulus of elasticity than that of the shadow mask such as a glass-based frit or a heavy metal such as tungsten or molybdenum.

Shadow mask damping for color CRT

An antiglare/antistatic coating for a cathode ray tube (CRT) is applied to the outer surface of the CRT's faceplate and includes a first inner hygroscopic layer of silane, water, sulfuric acid and an alcohol mixture which may be applied by dipping, spinning or spraying. The coating further includes a second outer layer of silanes, water, acid, epoxy, and a coupling agent balanced with an alcohol mixture which is sprayed onto the first inner layer. The grounded first inner layer possesses high conductivity for antistatic protection, while the second outer layer, which possesses glass-like characteristics, provides antiglare protection by reducing the faceplate's reflectivity. The second outer layer dries as a hard porous coating which resists scratching and allows water vapor to penetrate into the first inner hygroscopic layer to maintain its high conductivity.

Growing community of inventors

Arlington Heights, IL, United States of America

Hua-Sou Tong