Abstract:
A modular reflector assembly includes two portions arranged symmetrically at a common plane. Each portion includes a first surface defined by a first parabola rotated to a first angle relative to the plane and a second surface abutting the first surface defined by a second parabola rotated to a second angle greater than the first angle. A third surface abuts the second surface and is defined by a third parabola rotated to a third greater than the second angle. A fourth surface abuts the third surface and is defined by a fourth parabola rotated to a fourth angle greater than the third angle. A fifth surface abuts the first surface and is defined by a fifth parabola rotated in the common plane to a fifth angle relative to the first axis.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application Ser. No. 61/915,199, filed Dec. 12, 2013, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject invention relates to strobe and reflector units. More particularly, the subject invention relates to strobe and reflector units utilized to provide visual warnings of alarm conditions. 
     Many varieties of strobe and reflector combinations are utilized as visual warning devices in warning systems, for example, fire detection systems. When the fire detection system is triggered by, for example, smoke or flame conditions detected by the fire detection system, the strobe and reflector combination is activated, often in conjunction with an audible alarm. Different fire detection systems and/or jurisdictions require the light emitted by the strobe and reflector combination to produce a particular output pattern, meeting standards, such as those set by Underwriters Laboratories (“UL”). The goal when configuring the strobe and reflector combination is to produce the required output pattern with the required illumination, while minimizing the power requirements to do so. 
     BRIEF DESCRIPTION 
     In one embodiment, a modular reflector assembly includes two portions arranged symmetrically at a common plane. Each portion includes a first surface intersecting the common plane defined by a first parabolic curve revolved about a first axis of revolution rotated to a first angle relative to the common plane and a second surface abutting the first surface defined by a second parabolic curve revolved about a second axis of revolution rotated to a second angle relative to the common plane, the second angle having a value greater than the first angle. A third surface abuts the second surface and is defined by a third parabolic curve revolved about a third axis of revolution rotated to a third angle relative to the common plane, the third angle having a value greater than the second angle. A fourth surface abuts the third surface and is defined by a fourth parabolic curve revolved about a fourth axis of revolution rotated to a fourth angle relative to the common plane, the fourth angle having a value greater than the third angle. A fifth surface abuts the first surface and is defined by a fifth parabolic curve revolved about a fifth axis of revolution rotated in the common plane to a fifth angle relative to the first axis of revolution. A sixth surface abuts the fifth surface and is defined by a sixth parabolic curve revolved about a sixth axis of revolution rotated in the common plane to a sixth angle relative to the first axis of revolution, the sixth angle having a greater value than the fifth angle. 
     In another embodiment, a strobe assembly includes a light source disposed along a source axis and a modular reflector assembly including two portions arranged symmetrically at a common plane including the source axis, each portion including a first surface intersecting the common plane defined by a first parabolic curve revolved about a first axis of revolution rotated to a first angle relative to the common plane and a second surface abutting the first surface defined by a second parabolic curve revolved about a second axis of revolution rotated to a second angle relative to the common plane, the second angle having a value greater than the first angle. A third surface abuts the second surface and is defined by a third parabolic curve revolved about a third axis of revolution rotated to a third angle relative to the common plane, the third angle having a value greater than the second angle. A fourth surface abuts the third surface and is defined by a fourth parabolic curve revolved about a fourth axis of revolution rotated to a fourth angle relative to the common plane, the fourth angle having a value greater than the third angle. A fifth surface abuts the first surface and is defined by a fifth parabolic curve revolved about a fifth axis of revolution rotated in the common plane to a fifth angle relative to the first axis of revolution. A sixth surface abuts the fifth surface and is defined by a sixth parabolic curve revolved about a sixth axis of revolution rotated in the common plane to a sixth angle relative to the first axis of revolution, the sixth angle having a greater value than the fifth angle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawing in which: 
         FIG. 1  is a perspective view of an embodiment of a strobe assembly; 
         FIG. 2  is a schematic plan view of an embodiment of a strobe assembly; 
         FIG. 3  is a plot of an output pattern of an embodiment of a strobe assembly; 
         FIG. 4  schematically illustrates horizontal and vertical illumination planes and a source axis of an embodiment of a strobe assembly; 
         FIG. 5  is a schematic illustration of surface A of an embodiment of a strobe assembly; 
         FIG. 6  is a schematic illustration of surface B of an embodiment of a strobe assembly; 
         FIG. 7  is a schematic illustration of surface C of an embodiment of a strobe assembly; 
         FIG. 8  is a schematic illustration of surface D of an embodiment of a strobe assembly; 
         FIG. 9  is a schematic illustration of surface E of an embodiment of a strobe assembly; 
         FIG. 10  is a schematic illustration of surface G of an embodiment of a strobe assembly; 
         FIG. 11  is a schematic illustration of surface H of an embodiment of a strobe assembly; 
         FIG. 12  is a schematic illustration of the output of the strobe assembly in the horizontal plane; and 
         FIG. 13  is a schematic illustration of the output of the strobe assembly in the vertical plane. 
     
    
    
     DETAILED DESCRIPTION 
     Shown in  FIG. 1  is a strobe assembly  10 , including a source  12  and a reflector  14 . The reflector  14  is formed of a multiple of reflector surfaces having a mirror finish via plating, polishing or the like, shown in  FIG. 2 . As will be described in greater detail below, the reflector surfaces are arranged to produce a T-shaped output pattern  16 , shown for example in  FIG. 3 , such as that required by standards such as UL 1971. The reflector arrangement optimizes light energy in forming the required pattern while minimizing light energy projected to areas where it is not required, thus reducing the amount of energy required to operate the assembly  10 , allowing for more assemblies  10  to be utilized on a system loop, thus reducing the cost of the overall fire detection system. 
     Referring again to  FIG. 2 , the reflector  14  includes a plurality of reflector sets: A, B, C, D, E, F, G, and H having a common focal point  18  to direct illumination to form the output pattern  16 . The surfaces A-H have varying focal lengths in aiming directions as described in more detail below. They are focused around the common focal point  18 , which is located at a center of the source  12 , best shown in  FIG. 4 . As those skilled in the art will appreciate, the optical emissions from the reflector  14  are in part measured relative to predetermined horizontal and vertical planes, such as planes  22  and  24 . The planes  22  and  24  are orthogonal to one another and intersect at the source axis  20 . In a wall mountable configuration, the source axis  20  extends generally perpendicular to the wall. The surface pairs A-G are stacked partial parabolic surfaces, which are arranged symmetrically relative to the vertical plane  24 . 
     As illustrated in  FIG. 5 , surface A is formed of a portion of parabola A′ having a focal length  26   a , which in an exemplary embodiment is about 0.49 inches. The parabola A′ is revolved around the source axis  20  to form the surface A. One skilled in the art will appreciate that surfaces B and surfaces E truncate surface A along their intersecting curves  28 , as shown in  FIG. 2 . 
     As shown in  FIG. 6 , parabola B′ is used to form each of the surfaces B on each side of vertical plane  24 . Parabola B′ is defined in the horizontal plane  22  and has a focal length of  26   b , which in an exemplary embodiment is about 0.509 inches. An axis of revolution  30   b  of parabola B′ is rotated through a tilt angle  32   b , which in an exemplary embodiment is about 10 degrees relative to the source axis  20 . Parabola B′ is then revolved around axis  30   b  to form surface B, best shown in  FIG. 2 . As with surface A, surface B is truncated at its intersection with surface A at curves  28 , and at its intersections with surfaces C at curves  34 , as shown in  FIG. 2 . 
     Referring now to  FIG. 7 , parabola C′ is used to form each of the surfaces C on each side of vertical plane  24 . Parabola C′ is defined in the horizontal plane  22  and has a focal length of  26   c , which in an exemplary embodiment is about 0.542 inches. An axis of revolution  30   c  of parabola C′ is rotated through a tilt angle  32   c  of about 20 degrees relative to the source axis  20 . Parabola C′ is then revolved around the axis  30   c  to form the surface C. Each surface C is truncated at its intersection with surface B at curves  34  and at its intersection with surface D at curves  36  and surface E at curves  38 , as shown in  FIG. 2 . 
     Referring now to  FIG. 8 , parabola D′ is used to form each of the surfaces D on each side of the vertical plane  24 . Parabola D′ is defined in the horizontal plane  22  and has a focal length of  26   d , which in an exemplary embodiment is about 0.590 inches. An axis of revolution  30   d  of parabola D′ is rotated through a tilt angle  32   d  of about 45 degrees relative to the source axis  20 . Parabola D′ is then revolved around the axis  30   d  to form the surface D. Each surface D is truncated at its intersection with surface C at curves  36  and surface E at curves  38 . Further, each surface D is truncated by intersection with a base surface  40  orthogonal to source axis  20 , defining curves  42 , as shown in  FIG. 2 . 
     Surface E straddles the vertical plane  24  and extends between surface A and the base surface  40 . Referring now to  FIG. 9 , parabola E′ is used to form surface E. Parabola E′ is defined in the vertical plane  24  and has a focal length  26   e , which in an exemplary embodiment is about 0.58 inches. An axis of revolution  30   e  of parabola E′ is rotated through a tilt angle  32   e  of about 30 degrees relative to the source axis  20 . Parabola E′ is then revolved around the axis  30   e  to form the surface E. 
     Referring to  FIG. 10 , surface G is formed using parabola G′ having a focal length  26   g , in an exemplary embodiment, of about 0.940 inches in a plane parallel to the base surface  40 . The parabola G′ is extruded or translated along the source axis  20  from the base surface  40  to form surface G. 
     As illustrated in  FIG. 11 , surface set H includes two surfaces H, one disposed at each side of the vertical plane  24 . Each surface H is defined by a parabola H′ in a plane parallel to the base surface  40 , parabola H′ having a focal length  26   h , in an exemplary embodiment, of about 0.760 inches. The parabola H′ is extruded or translated along the source axis  20  from the base surface  40  to form the surface H. The surfaces H are truncated by the horizontal surface  22 . 
     This arrangement of surfaces A-H produces the T-shaped output pattern  16  shown in  FIG. 3 , with the contributions from the surfaces A-H shown in  FIGS. 12 and 13 . In the horizontal plane, light reflected from surface A is the main contributor between about −10 degrees and about +10 degrees, while the contributions of surface set B are focused on the ranges between about −5 degrees and about −15 degrees, and about +5 degrees and about +15 degrees. The light reflected from surface set C contributes most to the pattern in the ranges of about −15 degrees to about −25 degrees and about +15 to about +25 degrees, while surface set D contributes most in the ranges of about −25 degrees to about −55 degrees and about +25 degrees to about +55 degrees. Finally, surface set H is the main contributor to the pattern in the ranges of about −55 degrees to about −90 degrees and about +55 degrees to about +90 degrees. 
     Referring to  FIG. 13 , in the vertical plane, light reflected from surface A is the main contributor to the pattern between about −10 degrees and about +10 degrees. Surface E contributes most to the pattern in the range of about −10 degrees to about −60 degrees, while surface G contributes most in the range of about −60 degrees to about −90 degrees. Referring again to  FIGS. 2 and 3 , surfaces F shown in  FIG. 2  are the main contributors to the 45 degree spot portions  42  of the output pattern  16  of  FIG. 3 . 
     The reflector arrangement disclosed herein improves efficiency of the strobe assembly  10  in forming the required pattern while minimizing light energy projected to areas where it is not required, thus reducing the amount of energy required to operate the strobe assembly  10 . 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.