Abstract:
A wall-mountable strobe unit emits radiant energy over a one hundred eighty degree arc in a horizontal plane and over a ninety degree arc in a vertical plane when so mounted. The unit includes a reflector and an elongated light source. The elongated light source is symmetrically positioned on the reflector with one end thereof carried on the reflector with the light source extending in the horizontal plane when so mounted. The reflector includes first and second planar elements symmetrically located with respect to the light source. The planar elements are joined by symmetrically located curved elements formed of partial parabolic surfaces. The partial parabolic surfaces extend from the planar elements first rising a predetermined amount from the planar elements and then falling back toward the planar elements. Two additional partial parabolic surfaces are positioned adjacent to the planar surfaces, symmetrically located with respect to the light source and displaced from the parabolic surfaces with the planar surfaces therebetween.

Description:
FIELD OF THE INVENTION 
     The invention pertains to strobe units which emit high intensity pulses of radiant energy over wide viewing fields. More particularly, the invention pertains to such strobe units wherein an elongated cylindrical light source extends from a reflector in a plane of symmetry so as to emit light at least over a one hundred eighty degree arc in a horizontal plane and at least over a ninety degree arc in a vertical plane. 
     BACKGROUND 
     High intensity strobe units for emitting pulses of radiant energy over large viewing angles are known. One such structure is disclosed and claimed in Moran U.S. Pat. No. 5,448,462 assigned to the Assignee of the present invention. 
     While known units provide appropriate levels of visible radiant energy over wide angles, such as would be used to visually indicate a fire alarm, it would be desirable to be able to improve the efficiency of such units and reduce the electrical power required to drive such units. Reduction of electrical power, if achievable, is particularly important in that more strobe units can be driven from the same size power supply, using the same size distribution cables, then would heretofore be feasible. 
     In addition to reducing the amount of energy needed to energize a given unit, it would be desirable to provide as much light as possible to coordinates off of the horizontal and vertical planes. Preferably expanding the light output field could be achieved without introducing undue complexity into the structure of the unit. 
     SUMMARY OF THE INVENTION 
     A strobe unit includes a wall mountable housing. Electronic drive circuitry is carried by the housing. 
     An elongated light source which has a central axis and first and second displaced ends along that axis is also carried by the housing. The first end of the light source engages the housing and the light source is oriented with its axis extending horizontally when the housing is wall mounted. When so mounted, the light source extends perpendicular to the wall. 
     A reflector is carried by the housing. The reflector partially surrounds the elongated light source with the axis of the light source extending in a plane of symmetry of the reflector. 
     The reflector includes first and second mirror image elements wherein the elements abut each other and are positioned on opposite sides of the plane of symmetry. At least some of the elements include a plurality of convex, elongated, partial parabolic segments. 
     When the light source is energized by the electronic drive circuitry, it emits pulses of light which can be viewed directly by an individual in the vicinity of the housing. Additionally, the source emits light which is reflected by the reflector before being viewable by the individual. 
     The source emits light directly and without blockage along an arc on the order of one hundred and eighty degrees. The arc is symmetrically located relative to the axis of the elongated source and is oriented so as to be perpendicular to the plane of symmetry of the reflector. 
     In one aspect, first and second partial parabolic surfaces are carried by the reflector wherein the surfaces are oriented so as to extend parallel to the axis of the source. The surfaces have a height which is comparable to the length of the elongated source. The source is located at a focal point of the partial parabolic reflector elements. 
     In yet another aspect, light output is improved by providing first and second regions at distal ends of the first and second partial parabolic reflectors. The first and second regions are located at a predetermined angle with respect to the respective reflector element. The regions are planar and extend parallel to the axis of the light source and at a constant distance with respect thereto. 
     Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a strobe unit in accordance with the present invention; 
     FIG. 2 is a top plan view of the reflector and light source of the strobe unit of FIG. 1; 
     FIG. 3 is a front elevational view of the reflector and light source of the strobe unit of FIG. 1; 
     FIG. 4 is a side elevational view of the reflector and light source of the strobe unit of FIG. 1; 
     FIG. 5 is a sectional view taken along plane 5--5 of FIG. 2; 
     FIG. 6 is a sectional view taken along plane 6--6 of FIG. 2; 
     FIG. 7 is a wire-frame perspective view of the strobe unit of FIG. 1 illustrating various output rays of light; 
     FIG. 8 is a top plan wire-frame view of the unit of FIG. 1 illustrating rays of light output from the source; 
     FIG. 9 is a front elevation wire-frame view of the unit of FIG. 1 illustrating rays of light output from the source; 
     FIG. 10 is a side elevational wire-frame view of the unit of FIG. 1 illustrating rays of light output from the source; 
     FIG. 11 is an enlarged partial view of the unit of FIG. 1 illustrating segments of some of the reflector elements of FIG. 1; 
     FIG. 12 is a perspective view of a preferred embodiment of the reflector and associated light source; 
     FIG. 13 is a top plan view of the reflector and light source of FIG. 12; 
     FIG. 14 is a front elevational view of the reflector and light source of FIG. 12; 
     FIG. 15 is a side elevational view of the reflector and light source of FIG. 12; 
     FIG. 16 is a top plan wire frame view of the reflector of FIG. 12; 
     FIG. 17 is a perspective wire frame view of the reflector of FIG. 12; 
     FIG. 18 is a perspective view of another reflector; 
     FIG. 19 is a top plan view of the reflector of FIG. 18; 
     FIG. 20 is a top plan view of the reflector of FIG. 18; 
     FIG. 21 is a side elevational view of the reflector of FIG. 18; 
     FIG. 22 is a top plan, wire frame view of the reflector of FIG. 18 illustrating elements of the reflector of FIG. 18; 
     FIG. 23 is a wire-frame perspective view of the reflector of FIG. 18 illustrating rays of light output from the source; 
     FIG. 24 is a top plan wire-frame view of the reflector of FIG. 18 illustrating rays of light output from the source; 
     FIG. 25 is a front elevation wire-frame view of the reflector of FIG. 18 illustrating rays of light output from the source; and 
     FIG. 26 is a side elevational wire-frame view of the reflector of FIG. 18 illustrating rays of light output from the source. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this invention is susceptible of embodiment in many different forms, there are shown in the drawing and will be described herein in detail specific embodiments thereof 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 embodiments illustrated. 
     FIG. 1 illustrates a view in perspective of a strobe unit 10 in accordance with the present invention. The unit 10 includes a housing 12, illustrated in phantom, and drive circuitry 14 carried by the housing 12. 
     The housing 12 also includes a multi-element reflector indicated generally at 16 and an elongated light source, which could be a gas filled glass tube, 18. 
     The light source 18 has first and second ends generally indicated at 18a and 18b. The source 18 is carried at end 18b on either the reflector 16 or the housing 12. 
     The housing 12 is intended to be wall mounted, on a vertical wall, in a normal installation. When so mounted, the source 18 extends generally horizontally and is perpendicular to the wall upon which the housing 12 is mounted. The wall thus forms a vertical plane and the light source 18 extends in a horizontal plane. 
     The reflector 16 can be molded plastic with a deposited or a painted reflective exterior surface applied thereto. It will be understood that the exact composition of the material which makes up the reflector 16 is not a limitation of the present invention. 
     The reflector 16 is formed of a plurality of elements which are symmetrically located with respect to a plane of symmetry. This plane of symmetry is best illustrated in FIG. 2 and is identified by identification numerals 6--6. Thus, the plane which identifies the section of FIG. 6 also is the plane of symmetry of the reflector 16. 
     The reflector 16 includes the following elements: 
     Elements 24a, 24b are planar elements having first and second ends wherein the first ends 24a-1 and 24b-1 are located adjacent to and on opposite sides of the source 18. The planar elements 24a and 24b are bounded by first and second regions 24a-3, 24a-4 and 24b-3, 24b-4. The planar regions 24a, 24b extend preferably at an angle on the order or seventy-five degrees from an axis A of the light source 18 (best seen in FIG. 5). 
     Positioned adjacent to the planar surfaces 24a, 24b are first and second partly curved surfaces 26a, 26b. The surfaces 26a, 26b extend coextensive with the planar surfaces 24a, 24b and are located on opposite side of the elongated light source 18. The elements 26a, 26b are mirror images of one another. Each of the surfaces 26a, 26b is formed of seven elongated, partial, parabolic, aiming sections which are used to direct light emitted by the source 18 after a reflection, in a variety of directions, as discussed subsequently. 
     The reflector 16 also includes first and second symmetrical, generally curved reflector sections 28a and 28b. The sections 28a, 28b are coextensive with previously discussed sections 26a, 26b and coextensive with each other. 
     Each of the sections 28a, 28b abuts the source 18. They are symmetrically disposed with respect thereto. The sections 28a, 28b are mirror images of each other. The sections 26a, 26b are mirror images of each other. 
     The reflector 16 also includes sections 30a and 30b, each of which is formed as a partial parabolic reflector element wherein the source 18 is located at a focal point thereof. The elements 30a, 30b, are extended linearly along the axis A of the source 18 and are essentially parallel thereto. The elements 30a, 30b emit light from the source 18 at angles at 0 to 90° in the horizontal plane, as discussed subsequently. 
     The reflector surfaces 30a, 30b extend coextensive with the planar surfaces 24a, 24b along intersection regions 24a-3 and 24b-3. 
     FIG. 2 is a top view of the reflector 16 and light source 18. FIG. 2 illustrates an arc A1 which extends through an angle of more than one hundred and eighty degrees around the source 18. The arc A1 indicates a viewing angle around the source 18 wherein radiant energy emitted from the source may be directly viewed by an individual without requiring intervening reflections. FIG. 3 and FIG. 4 are front and side elevational views respectively. 
     FIG. 5 is a sectional view taken along plane 5--5 illustrating planar elements 24a, 24b, oriented at an angle on the order of twenty-five degrees relative to a perpendicular to the axis A of the source 18. FIG. 6 a sectional view taken along plane 6--6, the plane of symmetry of the reflector 16, illustrates various of the reflective elements. FIG. 6 also illustrates arc A2 which extends through an angle of ninety degrees and is indicative of a viewing angle of light from the source 18 in a vertical plane without intervening reflections. 
     FIGS. 7 through 10 illustrates perspective, front and side views respectively wherein the reflector 16 is illustrated in wire-frame form, for the purpose of indicating emission of light from the source 18 in various directions. As illustrated in FIG. 7, rays R1, R2 are directed, after one reflection, off of elements 30a, 30b respectively outwardly from the source 18 in a horizontal plane perpendicular to the axis of the source 18. 
     Rays R3, R4, some of which require two reflections, are directed horizontally off of the planar regions 24a, 24b in a horizontal plane toward the front of the unit, at angles of 0 to 50°. Ray R5 is directed primarily in a horizontal plane off of various portions of the parabolic sections 26a, 26b in a 10 to 60 degree range of the horizontal field. Rays R6 are reflected off of parabolic sections of elements 28a, 28b primarily in a vertical field at various angles. 
     FIGS. 8, 9 and 10 illustrate additional rays, some of which are reflected off of one or more elements of the reflector 16. 
     FIG. 11 illustrates in greater detail the structure and relationship of the multiple elongated partial parabolic segments which make up reflector elements 26a, 26b and 28a, 28b. Each element includes 7 parabolic sections such as 26a-1 to 26a-7, which direct light at selected angles relative to the horizontal or the vertical measuring, plane. 
     The elongated partial parabolic sections 30a, 30b contribute to light output in both horizontal and vertical profiles. In a horizontal profile, the light is directly from the source 18 at angles of 5 to 90 degrees in the horizontal plane. Additionally, sections 30a, 30b reflect light from the source 18 to sections 24a, 24b at angles of zero to about 50 degrees in the horizontal plane. 
     In the vertical plane, sections 30a, 30b reflect light from the source 18 at angles on the order of 10 to 50 degrees in the vertical plane. Sections 30a, 30b also reflect light to sections 24a, 24b which are emitted at angles of zero to 40 degrees in the vertical plane. 
     Planar sections 24a, 24b contribute to light output in both the horizontal plane and the vertical plane. Sections 24a, 24b reflect light from the source 18 at angles on the order of zero to 65 degrees in the horizontal plane. Additionally, sections 24a, 24b reflect light to sections 30a, 30b for output from sections 30a, 30b in the horizontal plane at angles 5 to 45 degrees. 
     Planar sections 24a, 24b contribute light from the source 18 to the vertical plane by reflecting light from the source at angles of zero to ten degrees in the vertical plane. Additionally, planar sections 24a, 24b reflect light to sections 30a, 30b respectively for output in the vertical plane at angles of zero to 15 degrees. 
     Sections 26a, 26b contribute output light primarily to the horizontal plane. Light from the source 18 is reflected directly therefrom at angles of zero to 65 degrees in the horizontal plane. Sections 26a,b-1 through 26a,b-3 reflect light from the source 18 in the horizontal plane at angles on the order of zero to 40 degrees. Sections 26a,b-4 through 26a,b-7 reflect light from the source 18 at angles on the order of 40 to 60 degrees in the horizontal plane. Sections 26a,b-1, reflect light from the source 18 at angles on the order of zero to 65 degrees in the horizontal plane. 
     Reflector sections 28a, 28b function identically to reflector sections 26a, 26b except that the light is output in the vertical plane. Additionally, sections 28a,b-1 through 28a,b-7 contribute reflected light from the source 18 at angles on the order of zero to 65 degrees in the horizontal plane. 
     FIGS. 12 through 17 illustrate a preferred reflector embodiment 16a. Elements in FIGS. 12 through 17 which are the same as in FIGS. 1 through 6 have been numbered accordingly. 
     The reflector 16a includes first and second elongated elements 40a, 40b which are located at the ends of the partial parabolic elements 30a, 30b. The elements 40a, 40b are planar and are oriented at an angle on the order of 32 degrees with respect to a plane which is perpendicular to the plane of symmetry, plane 6--6 indicated in FIG. 13. The planar elements 40a, 40b increase light output in the vertical plane. 
     In summary, reflectors of the type illustrated in FIGS. 1 through 17 include an elongated source of illumination which is intended to be oriented with an axis &#34;A&#34; which extends horizontally when the unit is mounted with a normal orientation. The reflector is symmetrical about a plane extending vertically through the horizontally extending axis of the source of illumination. 
     Extending from each side of the source of illumination, and parallel thereto, are first and second reflective surfaces which are identified as 30a,b in FIG. 1. The surfaces 30a, 30b have a partly parabolic shape. The source is located at the focus of the respective parabola. 
     The surfaces 30a, 30b, abut respectively reflective members 24a and 24b . The members 24a, 24b in turn abut and blend into a plurality of partial parabolic elements which form the surfaces 26(a) and 26(b). The elements 24a and 26a are mirror images of the elements 24b, 26b. 
     The regions 24a,b are substantially planar and extend from the surfaces 30a, 30b to a plane defined by the axis of the source, plane P H . The elements 24a, 24b extend at an angle on the order of 65 degrees relative to the axis A of the source. 
     Surfaces 26a,b which are formed of a plurality of curved partial parabolic elements curve toward the surfaces 28a, 28b. The elements 26a, 28a and 26b, 28b are mirror images. 
     The reflector of FIGS. 12-17 can be used with a common bulb 18 with three different drive circuits to produce 15, 75 and 100 candelas of light distributed in accordance with U.L. Standard 1971. In addition, the open structure of the disclosed reflectors produces a visible distribution of light off of the horizontal and vertical planes as required by U.L. 1971. 
     FIGS. 18 through 26 illustrate an alternate reflector 16b. The reflector of FIGS. 18 through 26 is intended to output 75 candelas of light when viewed head on and to conform to UL Standard 1971 for the horizontal and vertical distributions of light for a 15 candela source. 
     As illustrated, planar regions 24a&#39; and 24b&#39; extend from an axis A&#39; toward the outer edges of the reflector as is the case with regions 24a,b. The regions 24a&#39;,b&#39; extend at an angle on the order of 60° to the axis A&#39; of the source of illumination. 
     Regions 26a&#39;, 26b&#39;, 28a&#39; and 28b&#39; are identical partial parabolic reflectors. Sections 26a&#39;, 28a&#39; are mirror images of sections 26b&#39;, 28b&#39;. Section 24a&#39; is a mirror image of section 24b&#39;. FIGS. 23-26 are wire frame views of the reflector 16b illustrating exemplary reflections of light rays emanating from the source 18&#39;. 
     None of the reflectors described above incorporate elements which are trough-like and have opposing side surfaces. Hence, a continuous distribution of light will be produced from the elongated source about an angle A3, A3&#39; in a plane perpendicular to the axis of the source (which plane will be vertical when the axis of the source is oriented so as to be horizontal). This angle extends 180°, below the light source when the axis thereof extends horizontally. This continuously, emitted light pattern is achieved by not blocking out portions of the source with the reflector anywhere along the 180° extent of the angle A3 as illustrated in FIG. 13 and A3&#39; as illustrated in FIG. 19. 
     The non-trough like structure and exposed elongated source of the illustrated reflectors can also be expected to produce a light distribution at locations off of the horizontal and vertical planes P H  and P V , P&#39; H  and P&#39; V . 
     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 in tended 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.