Abstract:
A surface mountable strobe incorporates an elongated light source and a multi-element reflector. The reflector includes a first generally circular partial parabolic reflector element with an axis of rotation which corresponds to an axis of symmetry of the source. The first reflector element produces a spike of on-axis radiant energy which substantially exceeds the off-axis output profile. A plurality of spaced apart arcuate reflector elements provides output light profiles in horizontal and vertical planes which intersect at or near the axis of the source.

Description:
The benefit of an Oct. 19, 2001 filing date for Provisional Patent Application Ser. No. 60/346,123 is hereby claimed. 
    
    
     FIELD OF THE INVENTION 
     The invention pertains to reflectors for use in high intensity output strobe units. More particularly, the invention pertains to such reflectors which emit a spike of radiant energy in a direction generally on an axis of symmetry of a light source carried by the reflector. 
     BACKGROUND OF THE INVENTION 
     High intensity strobe units for emitting pulses of radiant energy over large viewing angles are known. One such structure is disclosed in Moran U.S. Pat. No. 5,448,462 to Moran, assigned to the Assignee hereof. Another is disclosed in Anderson U.S. Pat. No. 5,931,569 also assigned to the Assignee hereof. The disclosures of both patents are hereby incorporated by reference herein. 
     While known units are effective for providing alarm indicating levels of radiant energy over wide angles, they do not necessarily efficiently meet different requirements. One known light output profile for fire notification appliances is the U.L. 1971 light output profile, see FIG.  1 A. Another requirement that has emerged is to provide high intensity light output over a one hundred eighty degree angle in a horizontal plane and over a ninety degree angle in a vertical plane in combination with a higher intensity optical output spike, generally perpendicular to the unit, in both planes. This type of profile, the ADA 15/75 profile, is illustrated in FIG.  1 B. One known way to meet both of these requirements has been to use two different reflectors. One relative efficiently meets one standard. Another meets the other requirements. 
     Having to manufacture and to stock two different reflectors contributes to both manufacturing and inventory overhead. In addition, field personnel must be trained as to which of the two units must be installed in a given situation. Cost effectiveness will be enhanced without such additional overhead. 
     There thus continues to be a need for a unitary reflector solution to efficiently produce both of the described output patterns. Preferably, this solution will be readily manufacturable and will be aesthetically acceptable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a graph of a known light output profile, the UL1971 Standard; 
     FIG. 1B is another graph of a known light output profile, the ADA 15/75 Standard; 
     FIG. 2 is an isometric view of a reflector in accordance with the invention; 
     FIG. 3 is a top plan view of the reflector of FIG. 2; 
     FIG. 4 is a front elevational view of the reflector of FIG. 2; 
     FIG. 5 is a view taken along plane  5 — 5  of FIG. 3; 
     FIG. 6 is a view taken along plane  6 — 6  of FIG. 3; 
     FIG. 7 is a view taken along plane  7 — 7  of FIG. 6; 
     FIG. 8 is a sectional view taken along plane  8 — 8  of FIG. 3; 
     FIG. 9A is a graph of output in the horizontal plane of the reflector of FIG. 2 plotted against a composite UL/ADA profile with 75 candela output on axis; 
     FIG. 9B is a graph of output in the vertical plane of the reflector of FIG. 2 plotted against a composite UL/ADA profile with 75 candela output on axis; 
     FIG. 10 illustrates characteristics of a partial parabolic reflector adjacent to the source of the reflector in FIG. 2; 
     FIGS. 11A,  11 B together illustrate characteristics of a pair of parabolic surfaces that extend generally parallel to the source of the reflector in FIG. 2; 
     FIGS. 12A,  12 B together illustrate characteristics of a partial parabolic surface, between the surfaces of FIGS. 11A,  11 B, which extends generally parallel to the source; 
     FIGS. 13A,  13 B,  13 C together illustrate characteristics of three partial parabolic stacked surfaces which abut one another and which are symmetrically arranged relative to the source of the reflector in FIG. 2; 
     FIGS. 14A,  14 B together illustrate characteristics of partial parabolic surfaces located at ends of the reflector surfaces of FIGS. 11A,  11 B; 
     FIG. 15 illustrates characteristics of partial parabolic reflectors that extend from the surface of FIG. 10; 
     FIG. 16 illustrates characteristics of a partial parabolic reflector that extends from the surface of FIG. 10; 
     FIG. 17 illustrates characteristics of a partial parabolic reflector that extends from the surface of FIG. 16; 
     FIG. 18 is a ray diagram illustrating reflections of light rays off of surfaces of the reflector of FIG. 2; 
     FIG. 19 is another ray diagram illustrating reflections of light rays off of surfaces of the reflector of FIG. 2; 
     FIG. 20 is yet another ray diagram illustrating reflections of light rays off of surfaces of the reflector of FIG. 2; 
     FIG. 21 is a ray diagram illustrating reflections from different surfaces of the reflector of FIG. 2; 
     FIG. 22 is a ray diagram illustrating reflections from different surfaces of the reflector of FIG. 2; and 
     FIG. 23 is another ray diagram illustrating reflections from different surfaces of the reflector of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     While embodiments of this invention can take many different forms, specific embodiments thereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
     An integral, multi-element reflector can be mounted on a wall and will provide a light output profile in accordance with FIGS. 1A and 1B. It will be understood that the various surfaces of the reflector as well as the orientation of the reflector can be reconfigured for differing light output profiles without departing from the spirit and scope of the invention. 
     The reflector carries an elongated light source, a flashable, elongated gas tube which has an axis of symmetry which extends generally perpendicular to the reflector. When mounted on the wall, the axis of symmetry extends generally perpendicular to the wall. A spike of radiant energy in excess of 50 candela can be emitted in parallel with the axis of symmetry. 
     A radiant energy profile is emitted in a horizontal plane which includes the axis of symmetry. Another radiant energy profile is emitted in a vertical plane. The two planes intersect at the axis of symmetry of the bulb or source. 
     The on-axis spike of radiant energy is substantially reflected off of a partial parabolic reflector which is formed adjacent to a proximal end of the source. The remaining reflector elements contribute to meeting pre-determined horizontal and vertical output profiles. The exact profiles to be met are not limitations of the invention. 
     FIGS. 2-8 illustrate various aspects of a strobe unit  10  and reflector  14  in accordance with the invention. Strobe  10  includes a housing  12 , illustrated in phantom in FIG.  3 . The housing  12  carries the reflector  14  as well as drive circuitry  16 . An elongated light source  18 , symmetrical with respect to an axis A, is also carried on the reflector  14 . A proximal end  18   a  of source  18  extends into mounting feature  18   b  which positions the source. 
     The housing  12  can be attached to or mounted adjacent to a generally vertical surface such as a wall W. When so mounted, the elongated light source  18 , which could be a gas filled tube flashable by electronics  16 , as would be understood by those of skill in the art, extends generally perpendicular to the mounting surface W. The reflector  14  can be mounted with different orientations depending on the output requirements. 
     The axis A of the source  18  is located at the intersection of a horizontal plane H and a vertical plane V, best seen in FIG.  3 . Both planes extend generally perpendicular to the mounting surface W. Illumination profile requirements, such as exemplary profiles of FIGS.  1 A,B, are defined relative to planes H,V. Planes P, P 1  discussed subsequently, extend at a forty five degree angle between planes H,V. 
     Reflector  14  includes a surface  30  which is adjacent to a proximal end of source  18 . Surface  30  is a partial parabolic reflective surface with a focal point located at or about a center of the emissive volume of the source  18 , preferably on the order of one-half inch from the surface  30  on axis A. The surface  30  is formed by revolving a parabola, with that focal point, about the axis A, see FIG.  10 . 
     Light emitted from source  18  is reflected off of surface  30  in a direction generally parallel to axis A to produce a spike of on-axis output light readily seen by an observer displaced from unit  10 , and viewing the unit  10  on a line that lies in plane V. In the profiles of FIGS. 9A, B this spike is on the order of 90 candela. 
     The surface  30  extends symmetrically about the axis A through an angle A 1  on the order of 270-290 degrees. It will be understood that the exact geometrically dimensions of the surface  30  may vary without departing from the spirit and scope of the invention. 
     Surfaces  32   a,b  are mirror image partial parabolic surfaces that extend laterally from source  18 . Each of the surfaces  32   a,b  has the same focal point as the surface  30  at the source  18 , and extends linearly from the surface  30  on a line generally parallel to or slightly angled outwardly, on the order of 1-3 degrees from the axis A, see FIGS.  11 A,B. The surfaces  32   a,b  direct light generally in the horizontal plane H in angles from zero degrees to ninety degrees between the horizontal plane H and vertical plane V. 
     Surface  34  is a partial parabolic reflective surface which extends generally parallel to or is angled outward from the axis A, at an angle in a range of one to three degrees, symmetrically between the surfaces  32   a,b . The surface  34  is formed of a partial parabola which has a focal point at the center of the source  18 , approximately 0.18 inches therefrom. The surface  34  extends linearly from the surface  30  to a terminating edge  34   a , see FIGS.  12 A,B. The surface  34  focuses and directs light from source  30  generally in vertical plane V from five degrees to ninety degrees relative to the axis A. 
     Surfaces  36   a,b  are each formed from an identical portion of the rotated parabola used to create surface  30 . These surfaces correspond to the portion of that parabola which extends from the curved edge  30   a . That partial parabolic surface is rotated toward or canted toward the axis A an angle in a range of 12-16 degrees, preferably 14 degrees. This angle is measured relative to the tangent of the surface  30  at the edge  30   a  see FIG.  15 . 
     The surfaces  36   a,b  extend across an angle on the order of 70-80 degrees relative to the axis A, preferably on the order of 75 degrees. Surfaces  36   a,b  generally focus and project light from source  18  in the horizontal plane H at an angle from about five degrees to forty degrees relative to the axis A. 
     Reflector  14  also includes symmetrically located, stacked, surfaces  40   a,b    42   a,b  and  44   a,b . Each of these surfaces is formed of a swept partial parabola which aims incident radiant energy at a selected angle, relative to the axis A but generally in the horizontal plane H. 
     Surfaces  40   a,b  are partial parabolic and are formed of a parabola which has a focal point in the emissive center of source  18 , about nine tenths of an inch from the surface. The parabola is oriented to project light rays at an angle on the order of forty degrees relative to the axis A in the horizontal plane H, see FIGS.  13 A,B,C. The aiming parabola is then swept along a parabolic curve to provide the surfaces  40   a,b  which will in turn project the rays parallel to the horizontal plane at 40-45 degrees relative to the axis A. The surfaces  40   a,b  extend between surface  40 - 1 , at the periphery of the source  18  to the plane P, surface  40 - 2 , an angle on the order of forty-five degrees on both sides of plane V. 
     Surfaces  42   a,b  aim incident rays relative to the axis A on the order of thirty degrees. Surfaces  44   a,b  aim incident rays relative to the axis A on the order of fifteen degrees. These surfaces are formed of discrete, swept, partial parabolas as are surfaces  40   a, b . Surfaces  40   a,b    42   a,b  and  44   a,b  reflect incident rays to contribute to the light output profile in the horizontal plane H. 
     It will be understood that variations in the surfaces  40   a,b    42 , a,b  and  44   a,b  come within in the spirit and scope of the present invention. The exact details of those surfaces are not limitations of the invention. Alternately, multiple parabolic surfaces such as surfaces  36   a,b  could be used instead of surfaces such as  40   a,b    42   a,b  and  44   a,b.    
     Surfaces  50 ,  52  which extend arcuately from surface  30  are partial parabolic surfaces formed from extensions of the same parabola as formed surface  30 . Surface  30  is bounded in part by a curved periphery  30   b  displaced from source  18 . 
     Periphery  30   b  extends through plane V and is preferably symmetrical with respect thereto. The curvatures of periphery  30   a  and  30   b  are different in that periphery  30   b  is closer to axis A than is periphery  30   a . Periphery  30   b  is inset into surface  30  and is the interface to surface  50 . 
     Surface  50  is rotated or canted away from a tangent to surface  30 , best seen in FIG. 16, at an angle in a range of five to nine, preferably seven, degrees. Surface  50  terminates at a distal periphery  50   a  displaced from surface  30   b . Surface  52 , a further extension of the surface formed by the parabola for surface,  30  extends from periphery  50   a , symmetrical relative to plane V. Surface  52  is rotated or canted away from a tangent to surface  50 , at periphery  50   a  at an angle in a range of seven to fourteen, preferably ten degrees, best seen in FIG.  17 . 
     Surface  50  focuses and projects light from source  18  generally in vertical plane V through an angle of zero degrees to forty five degrees relative to the axis A. Surface  52  focuses and projects light from source  18  generally in vertical plane V in a region from fifteen degrees to fifty five degrees relative to the axis A. Surfaces  50 ,  52  extend through a ninety degree angle bisected by the plane V. 
     Table I, following, illustrates the contribution in the horizontal plane H, measured from the axis, for zero degrees, twenty five degrees and forty five degrees. At ninety degrees virtually all of the light is contributed by source  18  and respective surface  32   a, b . 
     
       
         
               
               
               
               
             
           
               
                 TABLE I 
               
               
                   
               
               
                 Surface 
                 0 Degrees 
                 25 Degrees 
                 45 Degrees 
               
               
                   
               
             
             
               
                 30 
                 91%  
                 12% 
                  0% 
               
               
                 32 a or b 
                 0% 
                 10% 
                 43% 
               
               
                 36 a or b 
                 0% 
                 44% 
                  0% 
               
               
                 40 a or b 
                 0% 
                  3% 
                 14% 
               
               
                 42 a or b 
                 0% 
                 13% 
                 22% 
               
               
                 44 a or b 
                 2% 
                 10% 
                  0% 
               
               
                 50 
                 7% 
                  0% 
                  0% 
               
               
                 Source 18, Direct 
                 0% 
                  8% 
                 21% 
               
               
                 Total 
                 100%  
                 100%  
                 100%  
               
               
                   
               
             
          
         
       
     
     FIG. 9A illustrates a light output profile of reflector  14  for the horizontal plane H plotted against a required composite UL/ADA horizontal plane output profile. FIG. 9B illustrates a light output profile of reflector  14  for the vertical plane V plotted against a required composite UL/ADA vertical plane output profile. 
     FIG. 18 illustrates, with respect to the front elevational view of reflector  14 , as in FIG. 4, representative light rays, from source  18  reflected off of various surfaces,  32   b ,  40   a ,  42   a  to an angle forty five degrees, relative to axis A, in the horizontal plane. FIG. 19 is a side elevational view which illustrates light rays from source  18  reflected off of various surfaces to thirty degrees in the vertical plane V, relative to the axis A. FIG. 20 is a top plan view, as in FIG. 3, illustrating the reflected rays of FIGS. 18,  19  in plane H and V. 
     Surfaces  54   a,b  extend from distal ends of surfaces  32   a,b  of reflector  14 . Surfaces  54   a,b  are formed of a partial parabola which directs light at an angle of forty five degrees in a plane perpendicular to the axis A. This parabola is extended or swept along a line rotated from or canted back at an angle of about twelve degrees relative to the axis A, best seen in FIG.  14 . Surfaces  54   a,b  direct light to a region forty five degrees off the horizontal plane H, forty five degrees off the vertical plane V and forty five degrees of the axis A out from the reflector  14 , a so-called compound forty five degree region. This region extends on a ray in a three dimensional coordinate system A, H, V along coordinates (1, 1, 1), (10, 10, 10) and so on. 
     FIGS. 21-23 illustrate rays of light from source  18  which are reflected off of surfaces  54   a,b  and directed toward the above noted compound forty five degree region. In FIG. 21 ray R 1  is illustrated originating at source  18  is reflected off of surface  54   b  to the compound forty five degree region. Rays R 2 , 3  are illustrated being directed off surface  54   a  directly at the location of the observer of FIG.  21 . 
     FIG. 22 illustrates ray R 1  looking parallel to surface  54   b . Ray R 1  is in plane P at forty five degrees to both the horizontal plane H and vertical plane V. FIG. 23 illustrates ray R 1  in a top plan view being reflected off of surface  54   b  toward the compound forty five degree region. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.