Patent Publication Number: US-2019198310-A1

Title: Gasket assemblies, uv lamp systems including such gasket assemblies, and related methods

Description:
FIELD 
     The invention relates to UV lamp systems, and more particularly, to improved gasket assemblies included in UV lamp systems. 
     BACKGROUND 
     Ultraviolet (UV) lamp systems have been in use for many years in applications such as, for example, UV curing. Many conventional industrial high wattage electrodeless UV curing lamp systems include an elongate lamp (irradiator module) which contains a tubular electrodeless bulb envelope powered by at least one magnetron mounted on waveguides that direct the microwaves (where the microwaves are a form of radio frequency radiation, referred to herein as “RF”) into a reflector cavity. U.S. Pat. No. 4,042,850 illustrates details of an example conventional system, the details of which are incorporated by reference herein. 
     Typically, magnetrons emit microwaves from an output antenna into a metal waveguide inside the lamp system which directs the RF into a reflector cavity containing the bulb envelope. An electrodeless bulb (e.g., a tubular quartz bulb) is filled with a small amount of mercury, an easily ionized gas such as Argon, along with other additives such as metal halide salts to modify and enhance the spectral output. The electric field generated by the magnetrons excites the gas inside the bulb to high energy levels, vaporizing and ionizing the mercury and additives. The resulting high energy collisions of the vaporized molecules cause the bulb to emit a large amount of UV energy. 
     Such microwave-excited lamps utilize an RF screen as a safety mechanism to shield microwave radiation leakage. A conventional RF screen assembly consists of many separate pieces assembled together. For example, such RF screen assemblies typically include four support gasket parts, four pieces of metallic braided gasket (typically stainless steel), a sheet of fine mesh RF screen material cut to fit, and a spot welded frame. The pieces of metallic braided gasket are placed around the edges of a frame bracket with two metal strips securing the fine mesh RF screen material. When the RF screen assembly is removed and re-installed (but not replaced with a new assembly during routine maintenance activities), the metallic braided gaskets can become compressed to such a state that a good seal is no longer viable. When this occurs, the lamp systems may shut down due to RF excessive RF leakage. Damage to any one part of the RF screen assembly may result in the entire assembly being completely discarded, because of the difficulty in assembly, and the limited knowledge of the user in connection with the assembly. 
     Thus, for these and other reasons, it would be desirable to improved gasket assemblies, and UV lamp systems including such improved gasket assemblies. 
     SUMMARY 
     According to an exemplary embodiment of the invention, a gasket assembly for use in a UV lamp system is provided. The gasket assembly includes an RF screen, and an elastomeric gasket material affixed to the RF screen. 
     According to another exemplary embodiment of the invention, a UV lamp system is provided. The UV lamp system: includes a housing; an electrodeless bulb configured to emit UV energy, the electrodeless bulb being positioned within the housing; and a gasket assembly coupled to the housing adjacent the electrodeless bulb. The gasket assembly includes an RF screen, and an elastomeric gasket material affixed to the RF screen. 
     According to yet another exemplary embodiment of the invention, a method of assembling a gasket assembly for use in a UV lamp system is provided. The method includes: providing an RF screen; and affixing an elastomeric gasket material to the RF screen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures: 
         FIG. 1A  is a perspective view of a UV lamp system in accordance with an exemplary embodiment of the invention; 
         FIG. 1B  is a partially exploded perspective view of the UV lamp system of  FIG. 1A ; 
         FIG. 2A  is a partially exploded perspective view of elements of a gasket assembly in accordance with an exemplary embodiment of the invention; 
         FIG. 2B  is a top view of the elements of the gasket assembly of  FIG. 2A ; and 
         FIG. 2C  is a further partially exploded perspective view of the elements of the gasket assembly of  FIG. 2A . 
     
    
    
     DETAILED DESCRIPTION 
     In accordance with certain exemplary embodiments of the invention, a gasket assembly is provided including two pieces of elastomeric gasket material (e.g., formed of silicone, a silicone based material, or another elastomeric material) are provided, each on one of two sides of a sheet piece of RF screen material. The pieces of elastomeric gasket material may be affixed to an RF screen, for example, using an adhesive (e.g., an epoxy adhesive). For example, the pieces of elastomeric gasket material may include conductive particles (e.g., graphite or metallic particles). For example, such conductive particles may be coated onto one or more surfaces of the elastomeric gasket material. In another example, such conductive particles may be dispersed throughout the volume of the elastomeric gasket material. 
     When assembled, such a gasket assembly including the two pieces of elastomeric gasket material and the sheet piece of RF screen material provides a high level of electromagnetic interference (EMI) shielding and environmental sealing over a wide temperature range. While aspects of the invention describe the elastomeric gasket material as “pieces” provided on sides of the RF screen material, it will be appreciated that the elastomeric gasket material may (or may not) be separate pieces of material. Thus, for example: (i) the elastomeric gasket material may be solid pieces of material, to be coupled to the RF screen; (ii) the elastomeric gasket material may be applied to the RF screen while in a non-solid form, where the elastomeric material later solidifies in contact with the RF screen as a single piece; among other potential applications of elastomeric material. 
     The gasket assembly may be sized to fit into a screen frame to provide a complete seal. In embodiments where the elastomeric gasket material is provided as one or more solid pieces of material, a special high temperature adhesive may be used to adhere the elastomeric gasket material pieces(s) onto the RF screen material, thereby providing a permanent glue seal. In another example, where the elastomeric gasket material is first provided in a non-solid form, the elastomeric gasket material may be applied to the screen material in a mold (e.g., when the gasket material is in a viscous and/or liquid form, such as a silicone based material). In a specific example, the elastomeric material may be affixed to the RF screen using a 3D printing process. 
     By using a flexible elastomer-based gasket, an improved seal is provided. By using this configuration, if the mesh RF screen were to become damaged, only the RF screen portion of the gasket assembly (including the elastomeric gasket material) would need to be replaced. The RF screen portion of the gasket assembly (including the elastomeric gasket material) is easily removed from the frame member/bracket such that the frame member/bracket is re-useable. 
     Thus, through the various exemplary embodiments of the invention described herein (and other embodiments within the scope of the invention), improved gasket assemblies (wherein a gasket assembly may also be referred to as a screen assembly or an RF screen assembly) are provided that utilize an elastomeric material encapsulating a portion (e.g., a perimeter) of a fine mesh RF screen and sized to fit into the screen frame member/bracket. By including the conductive particles within (and/or applied to a surface of) the elastomeric material, an electrically conductive gasket is provided that is desirably flexible and pliable. This flexible gasket assembly is then placed within the reusable frame member/bracket and, when installed as part of a UV lamp system (sometimes referred to as a lamp assembly), forms a desirable seal to contain RF radiation. 
     In exemplary gasket assemblies illustrated herein, two pieces of gasket material encapsulate the edges of the fine mesh RF screen making the entire gasket assembly flexible. The elastomer-based gasket and screen assembly forms a desirable compression seal to reduce RF leakage. This elastomeric gasket/RF screen assembly is a single piece including the RF wire mesh screen sandwiched between two elastomer gaskets pieces. The thickness of the elastomeric gasket material may determine the amount of rigidity. This gasket assembly (the elastomeric material affixed to the RF screen) uses less material since there are fewer pieces. This gasket assembly will allow the mounting bracket (sometimes referred to as a frame member) to be reused thereby reducing replacement cost. 
     Referring now to the drawings,  FIG. 1A  illustrates UV lamp system  100  including an inventive gasket assembly  106 .  FIG. 1B  is a partially exploded view of UV lamp system  100  (including housing  102 ), with gasket assembly  106  illustrated separate from the remainder of UV lamp system  100 . By separating gasket assembly  106  from the remainder of UV lamp system  100  in  FIG. 1B , certain other elements of UV lamp system  100  that are contained within housing  102  are visible including electrodeless bulb  104 , reflector(s)  108 , and reflector cavity  110 . As described above, electric field energy from magnetrons (included within housing  102 , but not visible in  FIG. 1B ) excite gas within electrodeless bulb  104 , resulting in the emission of UV energy from electrodeless bulb  104 . Such UV energy emitted from electrodeless bulb  104  may be used in applications such as, for example, UV curing applications. 
     Exemplary gasket assembly  106  is shown in  FIG. 2A , including element  106   a  (i.e., an RF screen, with elastomeric gasket material affixed to a perimeter area of the RF screen) and a frame member  106   b . Fasteners  106   c  are used to couple element  106   a  and frame member  106   b  to the remainder of UV lamp system  100 , as shown in  FIG. 1A . 
     For example, in  FIGS. 2A-2C : element  106   a  may represent an RF screen with solid pieces of elastomeric gasket material affixed thereto; element  106   a  may represent an RF screen with the elastomeric gasket material affixed/applied to the RF screen while the elastomeric gasket material is in a non-solid form (where the elastomeric gasket material later solidifies in contact with the RF screen as a single piece); among other potential representations of element  106   a  within the scope of the invention. 
       FIG. 2B  also illustrates element  106   a  and frame member  106   b  separated from one another, in a side by side arrangement. Element  106   a  includes an RF screen  106   a   1 , and an elastomeric gasket material piece  106   a   2  affixed to a first side of the RF screen, and an elastomeric gasket material piece  106   a   3  affixed to a second side of the RF screen (where the elastomeric gasket material piece  106   a   3  is not visible in  FIG. 2B , but see  FIG. 2C ). 
     Aspects of the invention also relate to methods assembling a gasket assembly (e.g., gasket assembly  106  illustrated in the drawings) for use in a UV lamp system is provided. Exemplary methods include providing an RF screen (e.g., RF screen  106   a   1  illustrated in the drawings) (e.g., to shield microwave radiation leakage in connection with the UV system), and affixing an elastomeric gasket material (e.g., elastomeric gasket material pieces  106   a   2 ,  106   a   3 ) to the RF screen. For example, the elastomeric material may be affixed to a perimeter area of the RF screen. The elastomeric gasket material may be affixed to the RF screen: as multiple solid pieces, one to each side of the RF screen; as a non-solid material (e.g., in a mold, in a 3D printing application, etc.); etc. 
     In accordance with the inventive methods disclosed herein, after securing the elastomeric gasket material to the RF screen (thereby providing a “gasket assembly”), the gasket assembly may be installed in a UV lamp system (e.g., see  FIGS. 1A-1B ). 
     Although the invention illustrates a specific implementation of a gasket assembly (including an RF screen sandwiched between two elastomeric gasket material portions/layers), it is not limited thereto. As will be appreciated by those skilled in the art, various alternative configurations of the inventive gasket assembly (and related UV lamp system) are contemplated. 
     Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.