MXPA99009942A - Elastomer lined crt-to-lens coupler - Google Patents

Abstract

A coupler for coupling a CRT faceplate (114) of a cathode ray tube to a lens (160). The coupler comprises a rigid portion (201) having a faceplate surface (202) for coupling to the faceplate (114) and a lens surface (203) for coupling to the lens (160). The coupler further comprises an elastomeric layer (220) disposed on at least the faceplate surface (202) and lens surface (203) of the rigid portion (201).

Description

CATHODIC RAY TUBE COUPLER COVERED WITH ELASTIC TO LENS Field of the Invention The present invention relates to housings for coupling cathode ray tubes (CRTs) to lenses and, in particular, to cathode ray tube couplers to lenses for optical systems. cathode ray tube projection television. BACKGROUND OF THE INVENTION Commonly, projection television cathode ray tube systems include three cathode ray tube units, one for each of the red, green and blue colors. Each cathode ray tube unit commonly comprises a cathode ray tube, a lens, a cathode ray to lens tube coupler, which couples the lens to the front plate of the cathode ray tube. The cathode ray tube projects light, which is amplified by the lens for its projection on another surface. Referring now to Figure 1, a cross-sectional view of an exemplary cathode ray tube unit 100 of the prior art for use in a projection television cathode ray tube system is shown. The cathode ray tube unit 100 comprises the cathode ray tube 110, the plastic lens 160 and the molded housing or coupler 140 for coupling the lens 160 to the front plate 114 of the cathode ray tube 110. cathode ray 110 comprises a phosphor surface 113 inside the cathode ray tube 110. As will be appreciated by those skilled in the art, the coupler 140 couples the lens 160 to the face plate 114 so that the lens 160 is positioned with respect to the cathode ray tube 110 in accordance with the approach and related requirements. The coupler 140 is coupled to the front plate 114 of the cathode ray tube 110 by the tension structure 111, stop bolts, such as the stop bolt 115, and compression springs, such as the compression spring 112. The lens 160 and the lens holding plate 161 are coupled to the coupler 140 and thus to the cathode ray tube 110 by lens fixing plate screws, such as the fixing plate screw 162. When the coupler 140 is assembled, the interior of the coupler 140 forms a cavity 146. The inner walls of the cavity 146 are the front plate of the cathode ray tube 114, the lens 160 and the inner walls 147 of the coupler 140. The cavity 146 is used to hold a fluid, which is designed to provide the correct refractive index for light to pass through the front plate of the cathode ray tube 114, the fluid in the cavity 146 and the lens 160. The fluid in the common cavity It includes a 70:30 mixture of ethylene glycol and glycerin. As will be appreciated, to prevent leakage of fluid, the front plate cap of the cathode ray tube 141 is interposed between the front plate 114 and the coupler 140, and the "O" shaped ring 142 is interposed between the lens 160 and the coupler 140. The shell 141 is seated in the channel 148 of the coupler 140, and the "O" shaped ring 142 is seated in the channel 149 of the coupler 140. The shell 141 and the "O" shaped ring. "142 are commonly elastomeric components that perform a sealing function. For example, imperfections in the adjacent surfaces of the faceplate 114 and the coupler 140 can prevent a perfect seal from forming if the shell 141 is not used. The shell 141 also performs a separation function, to maintain the face plate 114. physically separated from the coupler 140. For example, the coupler 140 may be molded and formed of a metal such as aluminum, which expands due to the heat produced during the operation of the cathode ray tube unit 100. The differential thermal expansion between the Coupler 140 and front plate 114 can cause coupler 140 to scratch the surface of faceplate 114. By physically separating face plate 114 from coupler 140, the shell 141 accommodates the differential thermal expansion of the face plate 114 and the coupler 140 while preventing damage to the face plate 114. The cathode ray tube unit 100 also comprises an expansion diaphragm 143, a diaphragm cover 144, and a diaphragm screw 145, which is used to couple the expansion diaphragm 143 to the coupler 140. As will be understood, the periphery of the front plate of the cathode ray tube 114 may have a rectangular, round or other shape. For example, when the front plate of the cathode ray tube 114 has a rectangular shape, the shape of the coupler 140 is also rectangular. Unfortunately, during the assembly of the cathode ray tube unit 100, the shell 141 may not always be properly seated in the channel 148 of the coupler 140, and the "O" shaped ring 142 may not always be properly seated in the channel 149 of the coupler 140. This can lead to leakage in the fluid in the cavity 146. Additionally, before the shell 141 or the "O" shaped ring 142 are deposited in the channels 148 or 149, respectively, a small piece of hair or other residue, or a defect in the molding of the coupler in the channel, can produce a leakage path for the fluid. It is undesirable that the scattered light is reflected from the inner walls 147 of the coupler 140. Therefore, the inner walls 147 are generally covered with a matte, dark opaque finish. One way to achieve this is to use anodized in black. Unfortunately, this can tend to release tiny particles that contaminate the cavity fluid. The anodized surface may be coated to solve this problem, but this can commonly include the use of an expensive coating material, for example a polymer material marketed by Union Carbide Corp., Electronics Division, of San Diego California, under the trademark registered PARYLENE®. An epoxy paint called "e-coat" can also be used, but it tends to have a higher reflectivity than is commonly desired. The reflectivity can also be reduced by texturizing the inner walls 147 to propagate scattered light. Unfortunately, said textured surfaces tend to erode from the molding tool after a limited number of cycles of "shootings". The erosion of the texturing detail of the molding tool occurs as a result of the interaction between the hot aluminum shot in the molding tool and the steel of the molding tool. Another problem with cathode ray tube units of the prior art such as the cathode ray tube unit 100 is that an untreated coupler formed of a material such as aluminum has a certain porosity in which the fluid in the tube can leak. cavity. Therefore, the mold 140 is generally impregnated with resin to seal the porosity in the mold, and a leakage test is performed in some cases. Another problem that commonly occurs with the cathode ray tube units is that, during assembly, the lens 160 must be aligned precisely with respect to the center of the front plate of the cathode ray tube 114. This commonly requires the use of a expensive cathode ray tube alignment machine. BRIEF DESCRIPTION OF THE INVENTION In accordance with a configuration of the invention described herein, a coupler for coupling a cathode ray tube front plate of a cathode ray tube to a lens comprises a rigid portion having a front plate surface of tube of cathode rays for coupling to the front plate of the cathode ray tube and a lens surface for coupling to the lens. The coupler further comprises an elastomeric layer disposed on at least the front plate surface of the cathode ray tube and the lens surface of the rigid portion. The foregoing and other aspects and advantages of the present invention will be apparent from the following description read in conjunction with the accompanying drawings., in which similar reference numbers designate the same elements. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: Figure 1 is a sectional cross-sectional view of a block diagram of a cathode ray tube unit of the prior art. Figure 2 is a sectional cross-sectional view of a cathode ray-to-lens tube coupler according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to Figure 2, a sectional cross-sectional view of a cathode ray tube-to-lens coupler 200 is shown, in accordance with the present invention. As will be appreciated, the coupler 200 can be used in place of a coupler of the coupler 140 of the cathode ray tube unit 100 of Figure 1, for coupling a cathode ray tube such as the cathode ray tube 110 to a lens such as the plastic lens 160. As will be understood, the lens 160 may also be formed of another suitable material such as, for example, glass. The coupler 200 comprises a rigid portion 201, having a front plate surface of cathode ray tube 202 for coupling to the front plate of the cathode ray tube 114 and a lens surface 203 for coupling to the lens 160. The coupler 200 additionally it comprises a layer of elastomeric material 220 disposed on at least the surface of the front plate of the cathode ray tube 202 and the surface of the lens 203 of the rigid portion 201 and, in one embodiment, also disposed on the inner surface portion 204 of the rigid portion 201. In one embodiment, the rigid portion 201 is a molding mold of a metal such as aluminum, and the elastomeric layer 220 is a rubber coating 220. The rubber coating 220 is preferably molded into the desired portions of the surface of the rigid portion or molding 201. The rubber coating 220 comprises several aspects, including appendages for centering 221, the flange of the shell 22 and rim pits of the shell 223, spacer portions 223a close to the pits 223, interior surface portion or anti-reflective surface finish 225 of rubber coating 220, and an "O" shaped ring rim. 227 and pit 228. In one embodiment, the mold 201 may be coated with rubber coating 220 by injection molding of liquid, as will be appreciated by those skilled in the art. In one embodiment, all portions of the rubber coating 220, except the centering appendages 221, have a similar cross section all around the coupler 200. However, the centering appendages 221 exist only in discrete locations along the periphery of the coupler 200, as will be described in more detail below. Thus, for example, the coupler 200 can have a rectangular shape, to conform to the shape of a cathode ray tube front plate. In this case, the coupler 200 will have upper and lower horizontal bars and vertical left and right bars, each of which has a cross section as illustrated in Figure 2. The rim of the cap 222 of the rubber coating 220 is formed on the surface side of the cathode ray tube front plate of the mold 201, and is designed to be sealably coupled to a cathode ray tube front plate such as the front plate of the cathode ray tube 114, as shown in FIG. Illustrated in Figure 2. The "O" shaped ring rim 227 is formed on the side of the lens surface of the mold 201, and is designed to be sealably coupled to a lens such as the lens 160, as it is illustrated in Figure 2. As will be appreciated, the rim of the cap 222 performs sealing functions similar to those performed by the cap 141 of the cathode ray tube unit 100, and the ring rim in the shape of "O". "227 performs sealing functions similar to those performed by the" O "shaped ring 142 of the cathode ray tube unit 100. The rubber coating spacer portions 223a 220 keep the mold 201 physically separated from the plate surface 114 and thereby perform separation functions similar to those performed by the shell 141 of the cathode ray tube unit 100. When assembled, the rim of the shell 222 is compressed and the excess rubber material can be exuded or compressed in the pits 223. Similarly, the "O" shaped ring flange 227 is compressed and the excess rubber material can be exuded or compressed in the flange 228 and the relatively flat area below the flange 227. However, an advantage of the rim of the shell 222 and of the rim of the "O" shaped ring 227, is that there is a reduced chance of leakage of fluid from the cavity. This is because the danger in the prior art that the cap 141 and the "O" shaped ring 142 are not always properly seated in their respective channels 148 and 149 of the coupler 140 is not present, as the flanges 222 and 227 they are already molded into the mold 201 of the coupler 200. Additionally, unlike the prior art, there is a reduced danger of molding defects or debris between the flanges 222, 227 and the mold 201, which could also cause a leakage path. To perform the separation and sealing functions described above, the rubber coating 220 is preferably a rubber material having a hardness between about 30 and about 50 on the edge scale A. The rubber coating 220 could also maintain integrity while in prolonged contact with the cavity fluid at normal operating temperatures) for example at about 85 degrees Celsius. Additionally, the rubber coating 220 is preferably a rubber material that has low reflectivity to light. The inner surface portion 225 of the rubber coating is also preferably molded with an anti-reflective surface finish or texture, such as slits, flanges, or mesh, to further reduce the reflectivity to light within a fluid cavity such as the fluid cavity 146. A molding advantage such as a texture in the mold of the rubber coating as opposed to molding a textured surface on the inner walls 147 of a molded aluminum coupler 140 is that the textured surfaces of the rubber coating 220 They do not have to erode from the molding tool so quickly. The use of the rubber coating 220 to reduce the light reflectivity within a fluid cavity also eliminates the need to coat the inner surface of the mold 201 with black anodization and either PARYLENE® or "e-coat". Additionally, since the rubber is flexible, slight biased cuts can be molded into the rubber coating 220, allowing a textured surface and other non-practical aspects with a molding of the mold 201. As the rubber performs a sealing function, the coating application of rubber 220 to the interior surfaces of the mold 201 eliminates the need to impregnate these surfaces with resin to seal the porosity of the mold. However, the application of a continuous layer of rubber to the interior surface of the mold 201 can also interfere with the transfer of heat from the cavity fluid to the mold. Therefore, in one embodiment, the rubber coating 220 is made as thin as possible in the inner surface portion of coating 225 such as to minimize the heat insulation properties of the rubber coating 220. In an alternative embodiment, a The finished open mesh surface on the inner surface portion 225 of the rubber coating 220 can be used to increase heat transfer from the cavity fluid to the mold 201. In this embodiment, the inner surface of the mold 201 is preferably impregnated for sealing and finished with a dark, matte finish to reduce reflectivity to light. Another useful aspect that can be formed in the rubber coating 220 is centering tabs 221. The use of centering tabs 221 avoids having the use of an expensive machine such as a cathode ray tube alignment machine. Such alignment is necessary because glass cathode ray tubes vary in their dimensions since the glass molds, which are used to form the cathode ray tubes, wear out over time. Thus, the alignment of the coupler with the cathode ray tube must be done to compensate for dimensional variations in the glass of the front plate of the cathode ray tube. Nevertheless, as the rubber coating 220 can conform to the variations in surfaces and objects, the centering appendages 221 can be designed in such a way that, when the coupler 200 is pushed down in a cathode ray tube front plate, the appendages of centering accommodate variations in the dimensions of the edges of the front plate of the cathode ray tube and perform the centering function. The centering tabs 221 are discreetly and preferably positioned around the periphery of the coupler 200 in a manner sufficient to properly align a lens and a cathode ray tube when coupled together with the coupler 200. For example, a plurality of centering tabs 221 in one embodiment is placed at regular intervals around the perimeter of the coupler 200. In an alternative embodiment, the centering tabs 221 are positioned in the four corners; or only in two opposite corners. The centering appendages 221 are formed in such a way as to form an outward spring when they are forced into the cathode ray tube in order to securely take and place the coupler 200 (and therefore the lens) to the face plate of the catheter. cathode ray tube in a predetermined position relative to the front plate of the cathode ray tube. Another advantage of using the centering appendages 221 in place of a cathode ray tube alignment machine is that it becomes possible to build a light barrier on the coupler 200.

Commonly, there is a significant amount of light shining from one cathode ray tube unit to another in a projection television system. The use of a cathode ray tube alignment machine requires access to the cathode ray tube alignment machine in areas of the cathode ray tube unit from which the light leaks. Consequently, light barriers must be added after alignment, commonly to the "green" cathode ray tube assembly. However, its a cathode ray tube alignment machine is not necessary because the centering appendages 221 perform this alignment function, the functionality of the light barrier can be molded in the rubber coating 220 or in the mold 201 . Although the present invention has been described above as having a coating 220 formed of rubber, in alternative embodiments other elastomeric compounds may be used, such as silicone rubber, or a thermoplastic elastomeric material, for example the thermoplastic elastomer marketed by Advanced Elastomer Systems, LP, from Akron, Ohio, under the trademark SANTOPRENE®. The elastomeric compound used to form the coating 220 preferably has a hardness between about 30 and about 50 on the edge scale A; is able to withstand prolonged contact with the cavity fluid at normal operating temperatures (e.g., up to approximately 85 degrees Celsius); and it is suitable for its application by means of an injection molding process. As will be appreciated by those skilled in the art, it must be ensured that the coating 220 adheres to the mold 201. Depending on the elastomeric compound used, various techniques can be used to ensure adequate adhesion. For example, with some elastomeric coatings, such as SANTOPRENE®, a wicked surface coating may be needed to apply to the mold 201 to ensure adhesion of the SANTOPRENE® coating. Alternatively, mechanical interlock can be used as will be appreciated by those skilled in the art.

Claims (9)

1. CLAIMS 1.A device for coupling a front plate (114) of a cathode ray tube to a lens (160), said apparatus comprises: a layer (220) of elastomeric material disposed on a surface (202, 203, 204) of said apparatus; first (222) and second (227) edges formed in said elastomeric layer, said first edge makes contact with said front plate and said second edge contacting said lens; and first (223) and second (228) pits positioned near said first and second edges, respectively, to receive such elastomeric material exuded from said first and second edges while said first and second edges are pressed against said front plate and said lens, respectively. The apparatus of claim 1, wherein said elastomeric layer (220) comprises an inner layer portion having a texture that serves to reduce the reflected light of said inner layer portion. The apparatus of claim 2, wherein said inner layer portion of said elastomeric layer (220) comprises a mesh surface finish. The apparatus of claim 1, wherein said elastomer layer (220) comprises a rubber material having a hardness in the range of about 30 and about 50 on an Edge A scale. 5. The apparatus of claim 4, wherein said elastomeric layer (220) is capable of maintaining integrity when in contact with a fluid comprising a mixture of ethylene glycol and glycerin. The apparatus of claim 5, wherein said fluid comprises a mixture of ethylene glycol and glycerin in a ratio of 70% ethylene glycol to 30% glycerin. 7. An apparatus for coupling a front plate (1 14) of a cathode ray tube to a lens (160) said apparatus comprises: a layer (220) of elastomeric material disposed on a front plate surface (202) of said apparatus; and a plurality of centering appendages (221) formed integrally with and exiting said layer. The apparatus of claim 7, wherein said plurality of centering appendages (221) is sufficient to secure said apparatus and said lens (160) to said face plate (14) at a predetermined position relative to the mentioned front plate. The apparatus of claim 8, wherein said faceplate (14) comprises four corners and said plurality of centering appendages (221) comprises a centering tab for corner cavity of said face plate.