Abstract:
A light weight reflector structure for an axial UV lamp wherein a shell-like channel housing supporting spaced apart ribs that in turn support flexed reflective spars that take the shape of the ribs. A preferred shape for the ribs and spars is parabolic about the axial UV lamp so that a beam is formed and directed out of the channel housing. The spars have a gap partially blocked by a deflector spar for creating a tortuous path for air forced direct into a tunnel between the channel housing and the spars. Forced air swirls through the gap and cools both the lamp and the spars.

Description:
TECHNICAL FIELD 
     The invention relates to portable and mobile reflectors for elongated lamps, particularly ultraviolet lamps. 
     BACKGROUND ART 
     Ultraviolet (UV) lamps are known for curing inks, adhesives, paint and similar coatings. Normally, such coatings would require hours to dry and harden but UV light usually causes molecular cross-linking and hardening within a few seconds. Because these coatings are usually applied to two-dimensional surfaces, it is advantageous to scan the surfaces with a UV beam tube that has a lengthwise or linear axial extent similar to a fluorescent tube so that the surface can be scanned in a series of parallel adjacent stripes. To concentrate the emission of such a linear tube, a parabolic or elliptical housing is used to reflect light from the tube over an extent that can be as narrow as a line for maximum concentration or a stripe parallel to the tube for a more useful surface scanning concentration. 
     In U.S. Pat. No. 6,739,716 to D. Richards, a UV lamp axial tube is shown having a reflector with two symmetrical parts on opposite sides of the tube. The reflector can focus UV light to a desired position such as a stripe of variable width. 
     One of the problems occurring with UV lamp axial tube reflectors is that both the lamps and reflectors reach high temperatures because the reflectors are used in closed proximity to surfaces being treated. Under such circumstances, heat can be trapped within the reflector causing a risk of burning the surface being treated or deformation of the lamp tube or the reflector itself. 
     In U.S. Pat. No. 5,003,185 to Burgio, Jr. a reflector assembly for a tube is shown to have both an air and water conduit extending through a reflector block for cooling purposes. Air is driven by blowers through ports in the reflector structure, while water is used to remove heat from the block. While this heat removal structure is useful, it is more suited to fixed positioning where a surface to be treated moves past the reflector structure. 
     A problem that has occurred in recent years is that graffiti is ubiquitous in certain urban areas. Graffiti abatement often consists of applying solvents, paint or other coatings to dissolve or cover the graffiti. Such surface treatments require curing assemblies of the prior art are not adapted for portable use. 
     An object of the invention was to devise a reflector structure for UV lamp axial tubes that was sufficiently light weight that the reflector could be moved with ease over a wall or surface being treated yet had adequate cooling for safety. 
     SUMMARY 
     The above object is achieved with an axial reflector structure for an axial UV lamp tube having both portability and forced air cooling. These features are achieved by using a plurality of thin, spaced apart ribs in a unitary, U-shaped channel housing that is a shell supporting shiny spars that form a reflector for beam formation. Spars are the principal lateral members of a framework that makes up the reflector structure of the present invention. At least one of the spars functions as an air deflector in the channel housing to provide a tortuous path to forced air flow in the housing, introducing swirling and vorticity of air against reflector spars and against the UV beam tube, thereby cooling both without use of water. The deflector spar, which is reflective, is placed rearwardly of the reflector spars so that the reflector is not a simple parabola or ellipse, but has an offset region where a gap is formed in the reflector spars to create the tortuous air flow path into the plenum. 
     The spars are formed of thin reflective strips having a length similar to the channel housing and the axial beam tube. The thin reflective spars are held in place by the ribs that have an inward shape in cross-section that defines the reflector shape, i.e., parabolic or elliptical. The outward shape of the ribs is designed to fit securely in the channel housing. Between the back side of the spars and the inside wall of the channel housing, a gas flow tunnel is found. Although the spaced apart ribs partially obstruct the tunnel, there is clearance for air flow through ports that are open to outside air through a fan. In other words, the gas flow tunnel is pressurized by fan modules joined to the channel housing that blow air into spaces between ribs, then through the gap in the spars establishing the tortuous air flow path mentioned above. 
     Air in the gas flow tunnel cools the back walls of the spars while swirling air forced into the plenum cools both the UV lamp and the reflective spars. The light weight channel housing, ribs, spars, lamp, and fan modules make up a portable UV lamp that can be hand held for use against vertical walls, as well as a portable mobile device that can be pushed over horizontal surfaces by a wheeled carriage. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a gas cooled reflector structure for axial lamp tubes in accordance with the invention. 
         FIG. 2  is a cross sectional view of the reflector structure of  FIG. 1 . 
         FIG. 3  is a bottom perspective view of a channel housing and ribs of the gas cooled reflector structure of  FIG. 1 . 
         FIG. 4  is a side elevational view of a rib illustrated in  FIG. 3 . 
         FIG. 5  is a side elevational view of the rib shown in  FIG. 4  with a pair of reflective spars in place. 
         FIG. 6  is a bottom view as in  FIG. 3  with a deflector spar in place. 
         FIG. 7  is a bottom view as in  FIG. 6  with a single reflector spar in place as well as a deflector spar. 
         FIG. 8  is a bottom view as in  FIG. 7  with two reflector spars in place as well as a deflector spar. 
         FIG. 9  is an alternate embodiment of the reflector structure shown in  FIG. 2 . 
         FIG. 10  is a perspective view of a wheeled carriage employing the reflector structure shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1 , a gas cooled reflector structure  11  has cross-sectional inverted U-shape with a lengthwise axis. An ultraviolet (UV) lamp tube  13  having a parallel lengthwise axis is mounted within the reflective structure  11 . The lamp tube  13  resembles a thin fluorescent tube and operates under similar high voltage conditions. 
     The reflector structure  11  has three major components, namely an outer channel housing  15 , internally spaced apart ribs  31 , and shiny reflective spars  25 ,  27 , and  29 . Channel housing  15  is seen resting on a work surface W, or held slightly above the work surface, for UV curing of a coating on surface S. An outer wall  17  of channel housing  15  supports a gas flow tunnel  45  having fan modules  53 - 59  serving as a means for pressurizing the tunnel. The central interior of reflective, where UV lamp tube  13  is located is a plenum  41 . Not shown are electrical connections to lamp tube  13 , with electrical wiring running through the upper interior of channel housing  15  above the reflective spars. Plenum  41  has an open face towards the work surface, S. UV light from the lamp tube is formed as a beam by means of the reflector structure for delivery to surface W. The channel housing  15  may be supported by a handle  63 , keeping the channel housing only a short distance above the work surface. A lower extent of the reflector structure is less than an inch away from the work surface so that a maximum amount of light beam energy is delivered to the work surface. Inks, paint, and coatings of various types may be cured by an ultraviolet radiation beam impinging on the coating. Not shown in  FIGS. 1-10  is a high voltage power supply to which the lamp tube is connected. Such power supplies are commercial units that can be provided with long electrical cords for attachment to a lamp tube as used in the embodiments of the invention shown herein. Drying time is cut from a matter of hours to a matter of minutes or seconds. 
     In  FIG. 2 , a gap  43  may be seen to exist between the shiny spars  25  and  27 , immediately below deflector reflective spar  29 . The gap is important for permitting flow of a coolant gas along flow path  50  beginning at a region outside fan  53 , through the fan and into gas flow tunnel  45 . Note that the deflector spar  29  is supported horizontally by a slot  30  in rib  31  in a location where spar  29  obstructs gas flow through the gap. This causes gas flow around the deflector spar  29  in a tortuous path with vorticity and swirling of air in the gas flow tunnel  45 . Because of gas pressure caused by fan  53 , gas flows through gap  43  and into the plenum  41  where gas cools the lamp tube  13  as well as shiny spars  25  and  27 . Any coolant gas may be used. In an ambient atmosphere of room temperature air, air will work well but other ambient gases will also work. 
     The shiny spars  25  and  27  are thin gauge metal strips that may be polished aluminum. The strips are initially flat but are flexed in a widthwise direction to take the shape of backing ribs. If the interior shape of the ribs is parabolic, the flexed shape of the spars will also be parabolic. The spars  25  and  27  are symmetric, with gap  43  separating the two spars. If light from the lamp tube  13  passes through gap  43  there is a good chance at angles near the vertical that the light will be reflected back into the plenum towards the work surface. The maximum opening of the plenum is a width dimension, W, that is typically 5 inches or less. This means that the reflector structure of the present invention can be used to treat stripes of a curable material with a stripe having a width W. The length of the stripe depends upon the axial length of the lamp tube and the channel housing. 
     With reference to  FIG. 3 , the U-shaped channel housing  15  is seen to have ribs  31 - 39  seated in place. The ribs are spaced apart by a distance dividing the channel housing into sections where one rib is in the middle of the air entry ports  71 - 74 , such as rib  34  is in the middle of port  72 , and intervening ribs are between ports. In this manner, each section is open to air ingress through a port. The ribs are secured in place by riveting or bonding or any metal joining technique. Note that each of the ribs  31 - 39  has a slot  81 - 89  with slots aligned so that a deflector spar can pass through each of the slots upon assembly of the reflector structure. Each spar also has a raised boss  91 - 99  that serves as abutment for ends of flexed reflective spars. Another abutment may be formed by the outer extent of the channel housing or tangs on the outer extent of the ribs. Each abutment allows a flat spar to be flexed to the parabolic shape of the inward curvature of the ribs and snap into place. This may be seen more clearly in  FIGS. 4 and 5 . 
     In  FIG. 4 , rib  31  has slot  81  for allowing a deflector spar to pass through. The raised boss  91  serves as an edge stop for two reflective spars held in place by tangs  101  and  102 . In  FIG. 5 , the shiny reflective spar  25  is about to be snapped in place in the direction of arrows A by the raised boss  91  and the tang  101 . Spar  27  is already in place. 
       FIG. 6  is similar to  FIG. 3  except that the shiny deflector spar  29  has been seated through the slots  81 - 89  in each of the ribs  31 - 39 . The deflector spar will deflect incoming air through the air entry ports  71 - 74 , causing vorticity and swirling of air as air under pressure meets flow resistance and deflection as shown in  FIG. 2  by the air flow path  50 . 
       FIG. 7  is similar to  FIG. 6  except that one of the reflective spars  25  has been seated against raised bosses  91 - 99  on the one hand and rib tangs, not shown, near the open face of the channel housing  15  on the other hand. As mentioned above, the reflector spar  25  is a flat strip of shiny metal which is retained in place by the ribs after flexing the strip in the axial direction so that each spar is retained between the raised bosses  91 - 99  and tangs on outer edges of the ribs. 
     Preferably the spars assume a parabolic or elliptical shape so that the reflective spars have a beam forming characteristic. A parabolic shape, with the beam tube placed at the axis of the parabolic shape will cause approximately parallel light rays to pass out of the channel housing. Moving the beam tube away from the central axial location in the channel housing, either closer to the work surface or away from the work surface, causes the output beam to have different focal characteristics that are shown in the art. By having the shiny reflective deflector spar  29  behind the gap formed by the two reflector spars, two affects are achieved. First, air is forced to circulate in a tortuous path described above. Secondly, the reflective character of the deflector spar causes light traveling into the gap to be reflected back into the plenum beyond the gap and become part of the beam so that not all light passing into the gap is lost. Some light, particularly at angles perpendicular to the deflector spar is not lost. With reference to  FIG. 8 , reflective spars  25  and  27  are shown in place. Auxiliary deflector spar  29  is shown to be outside of the plenum in channel housing  15 , slightly behind the reflector spars  25  and  27 . 
     With reference to  FIG. 9 , a channel housing  15  is shown to have two pair of reflector spars, namely  101  and  103  on one side of the raised boss  91  and spars  105  and  107  on the opposite side. The present invention is not limited to a pair of reflective spars on either side of boss  91 , but they employ any number of spars which work in combination with the auxiliary deflecting spar  29 . 
     With regard to  FIG. 10 , a reflector structure  11  is seen to be mounted in a wheeled frame  111  having rear wheels  113 , as well as a forward wheel, not shown. The wheels support the channel housing  11  in a ground clearance relation with less than an inch clearance from a work surface. An external conduit  115  can bring high voltage into the channel housing to supply the high voltage beam tube. Local current from an AC line  117  provides electricity for powering motors that drive the frame. The frame has an upright body  121  with a handle  123  at the top of the body for steering the apparatus which has the approximate shape and size of an upright vacuum cleaner. Channel housing  111  is moved over surfaces to be cured by pushing and pulling the frame so that light from the lamp tube reaches desired locations.