Patent Publication Number: US-4924365-A

Title: Adjustable reflector attachment

Description:
This invention relates to fluorescent lighting fixtures in general and more particularly to reflectors for lighting fixtures having asymmetric profile with reversible end plates. 
     BACKGROUND OF THE INVENTION 
     Explosion-proof lighting fixtures are used in applications where there is a possibility that internal arching may cause explosions which would otherwise propagate to an external explosive atmosphere. These explosion-proof lighting fixtures are constructed to exacting standards and are usually heavy duty and in fixed immobile locations. Because it is sometimes necessary to direct the light in a different direction, reflectors have been incorporated in these lights. 
     SUMMARY OF THE INVENTION 
     The present invention incorporates asymmetric parabolic reflectors that may be adjusted to direct light in different directions. The adjustment of the reflector is accomplished by loosening one screw axially mounted in the approximate center of the end plate of the reflector, so that a dimple locating means can be repositioned on the circumference of the tube around the lamps. In two light applications the reflector end plate is manufactured with symmetric dimples so that one extrusion can be used in a reverse position on both the right and left hand lamp tube. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a perspective view of an explosion-proof fluorescent light according to the present invention. 
     FIG. 2 is a front view of the end plate of the explosion-proof light shown in FIG. 1. 
     FIG. 3 is a side view of the end plate shown in FIG. 2. 
     FIG. 4A is a front view of the lamp tube assembly end cap with the end plate removed. 
     FIG. 4B is a cross sectional view of the lamp tube assembly end cap of FIG. 4A at section 4--4. 
     FIG. 4C is a rear view of the lamp tube assembly end cap of FIG. 4A. 
     FIG. 4D is a detail view of a portion of the lamp tube assembly end cap shown in FIG. 4C. 
     FIG. 5A is an end view of the reflector shown in FIG. 1. 
     FIG. 5B is a detailed view of a portion of the reflector shown in FIG. 5A. 
     FIG. 6 is a partial bottom view of the fluorescent light fixture of FIG. 1. 
     FIG. 7 is a sectional view of the fluorescent light at section 7--7 of FIG. 6. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring to FIG. 1, an explosion-proof fluorescent lighting fixture 10 is shown. The main components of explosion-proof fixture 10 are ballast housing 12, main housing 13, and lamp holders 14. A glass tube 17, is mounted over lamp holder 14 into housing 13 and contains fluorescent lamps 16. In this embodiment each glass tube 17 encloses two fluorescent lamps 16. Reflector 20 is mounted so that it directs fluorescent light as will be discussed in more detail below. 
     End plate 22 is attached to the end of reflector 20 and attached by screw 40 to lamp tube assembly end cap 24. As show in more detail in FIG. 2, end plate 22 has a screw 40 at the center of the end plate. There are two dimples or projections 42 and 43 located 180° apart. The dimples are coined in a metal end plate such that dimple 42 would be protruding out of the paper and dimple 43 protruding into the paper. This is shown more clearly in FIG. 3, which is a side view of end plate 22 shown in FIG. 2. End plate 22 is attached to reflector 20 by reflector screws 44. 
     FIG. 4A which is a front view of the lamp tube assembly end cap 24 with end plate removed. Cavities 46 are easily seen. These are indentations in end cap 24 and easily fit indented dimple 42. 
     In operation to change end point of the light, screw 40 would be loosened approximately one-half turn so that dimple 42 could ride up out of cavity 46 and the reflector could be rotated either clockwise or counter clockwise to change the aim point of the light. The screw would then be retightened, forcing dimple 42 into a different cavity 46. 
     A spring 41 is mounted on the end of the reflector 20 opposite screw 44. The spring holds the reflector to the lighting fixture 10 an allows the reflector 20 to be rotated about fixture 10. 
     Although the cavities 46 in end plate 24 are shown equally spaced around the circumference at 15° intervals, it will be readily appreciated that different spacings could be provided for. 
     End plate 22 is manufactured so that right and left end plates are made from the same stamping or coining process. It will be noted that dimple 42 which is pointing out of FIG. 2 and does not engage cavities 46, and dimple 43 which does engage cavities 46 and would be used on the right hand fixture in FIG. 1, if reversed 180°, end plate 22 could be used on the left hand fixture in FIG. 1 and dimple 42 would be pointed inward and engage cavities 46. Thus it is seen that end plates of asymmetrical design can be made in one stamping process and used for both right and left hand fixtures minimizing manufacturing cost. 
     In a like manner reflector 20 shown in FIG. 5 is asymmetric in shape. It is made from an aluminum extrusion with screw mounts 50 running the length of the reflector. The reflector is also manufactured in such a manner that it can be used either for the right or left hand reflector shown in FIG. 1 by simply reversing the orientation of the reflector front to back. Thus it is seen that even though the reflector is asymmetric, one extrusion process can be used to manufacture both right hand and left hand reflector.