Abstract:
A reflector for flashlights and other light emitting objects is disclosed which includes a generally deep dish shaped reflector member having a reflective inner surface. The reflector member has a rear vertex end and a forward open end and has a depth greater than the average diameter of said forward open end. Preferably the depth is at least 1.2 times greater than said average diameter of the forward open end. Also the reflector preferably has an optical axis and having a focus point located thereon at a location less than 10% of the distance from the rear vertex end to the forward open end of the reflector.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention. 
   The present invention relates to a reflector for flashlights and other light emitting objects. More specifically, it relates to a generally deep dish shaped reflector member having a depth greater than the average diameter of a forward open end thereof for providing an efficient focused beam of light. 
   2. Description of the Prior Art 
   A variety of reflectors have been proposed for flashlights and other light emitting objects. 
   Matthews, U.S. Pat. No. 6,386,730, discloses a flashlight having a head with two merged yet independent lamp/reflector systems. While Matthews teaches the provision of two reflectors, both reflectors are simply used to independently focus light from two light sources into the forwardly directed beam configurations. 
   McDermott, U.S. Pat. No. 5,894,196, discloses a compact lighting device including a light concentrating reflector directing light emitted by a light source toward a curved light refracting surface where it is refracted and thereby redirected. McDermott teaches the generation of substantially elliptical patterns of light. 
   Sharrah et al., U.S. Pat. No. 5,871,272, discloses a flashlight having a lamp head including a reflector having a major paraboloid reflective surface and a minor reflective paraboloid surface not interacting on the same light source. 
   Matthews et al., U.S. Pat. No. 6,046,572, discloses a flashlight having a flashlight beam is cast with a first lamp and reflector and an alternative second lamp and reflector assembly is substituted for the first lamp and reflector to provide a different configuration of beam illumination. 
   Goldfarb, U.S. Pat. No. 4,504,889, discloses a flashlight having a generally parabolic reflector and a beam-narrowing lens. 
   Uke, U.S. Pat. No. 5,103,381, discloses a lamp reflector of at least partially parabolic shape with a light source mounted at the focus. A lens is mounted between the light source and the open forward end a collimating pillar of transparent material is disclosed as extending inwardly from the center of the open end toward the lens. 
   Ellion, U.S. Pat. No. 5,459,649, discloses a flashlight with an enhanced spot beam and fully illuminated broad beam. A modified parabolic reflector is disclosed. 
   Fox, U.S. Pat. No. 5,630,661, discloses a metal arc flashlight. An elliptical reflector focus emitted light onto a diffusion screen and a movable collimating lens is disposed in front of the screen making the beam adjustable. 
   Ellion, U.S. Pat. No. 5,806,962, discloses a flashlight reflector which allegedly produces no bright and dull rings by utilizing more precise manufacturing tolerances. 
   Sedovic et al., U.S. Pat. No. 6,048,084, discloses a reflector for a flashlight having a pair of opposing walls forming a rectangular opening of area projection. 
   Peterson, U.S. Pat. No. 5,954,416, discloses a flashlight which utilizes a rotating reflector to eliminate a dark center ring which results if a light source is moved away from the focal point of a parabolically shaped reflector. 
   Hartley, U.S. Pat. No. 6,190,020, discloses a flashlight utilizing a light emitting diode light source with light dispersed away from a central axis. A collimating reflector is then utilized to produce a beam of light. Various diffusion methods are described. 
   Kish, et al, U.S. Pat. No. 5,957,567, discloses a flashlight which has a reflector which is axially movable with respect to the bulb to afford adjustable focusing of the light emitted from the bulb. The reflector also utilizes a facetted parabolic surface on a portion of the reflector. 
   Maglica, U.S. Pat. No. 6,170,960, discloses a miniature flashlight including a parabolic reflector such that rotation of the head relative to the barrel of the flashlight changes the focus of the flashlight beam. 
   Maglica, U.S. Pat. No. 6,428,182, discloses flashlight having a reflector and switch housing. The switch housing partially floats within the flashlight tube to allow for slight adjustment of the lamp relative to the reflector to insure centering of the lamp. 
   Sommers et al., U.S. Pat. No. 6,485,160, discloses a flashlight which utilizes a semiconductor light source a reflector and a lens to focus the light. In one embodiment three light sources with three reflectors and three lens are utilized to direct light toward a target area. 
   Osterhout et al., U.S. Pat. No. 4,876,632 discloses a flashlight which utilizes a LED light source and a parabolic reflector 30 (FIG. 2). 
   There remains a need for a reflector for flashlights and other light emitting objects which efficiently focus the light into a bright tightly focused beam. 
   SUMMARY OF THE INVENTION 
   The present invention provides a reflector for flashlights and other light emitting objects comprising a generally deep dish shaped reflector member having a reflective inner surface, said reflector member having a rear vertex end and a forward open end and having a depth greater than the average diameter of said forward open end. 
   Preferably the depth is at least 1.2 times greater than said average diameter of said forward open end. 
   Preferably the depth is at least 1.7 times greater than said average diameter of said forward open end. 
   Preferably the depth is at least 2.0 times greater than said average diameter of said forward open end. 
   The reflector preferably includes an optical axis and having a focus point located on said optical axis at a location less than 10% of the distance from the rear vertex end to the forward open end of said forward open end. 
   Preferably, the focus point is located on said optical axis at a location less than 5% of the distance from the rear vertex end to the forward open end of said forward open end. 
   Preferably, the focus point located on said optical axis at a location approximately 2% of the distance from the rear vertex end to the forward open end. 
   In one preferred embodiment, the focus point located on said optical axis at a location approximately 0.06 inches away from said vertex end. 
   Preferably, the reflector for flashlights and other light emitting objects has a light emitting element, said light emitting element having a light emitting surface, said reflector comprising a generally deep dish shaped reflector member having a reflective inner surface and having a rear vertex end and a forward open end, said reflector member having at least one cross sectional configuration in the form of a parabola formed according to the formula x 2 =(4) (f) (y) where x and y represent points on a Cartesian coordinate system and f is the distance of the focal point from the vertex of the parabola along an optical axis, said optical axis located along a line where x=0, and said vertex located at the point where x=0 and y=0, said reflector member having a circular opening formed at a forward end thereof at the location of a plane of truncation, said circular opening having a diameter D and said circular opening having a center point located on said optical axis, said plane of truncation intersecting said optical axis at a 90 degree angle and at a distance T from said vertex thus creating a reflector with a depth T, said light emitting surface having a center point located at the focal point of the reflector and wherein the ratio of the depth of the reflector T to said diameter of the reflector D to is at least 1.2, said focal point being located on said optical axis close to said vertex at a location less than 10% of the distance from the vertex to said plane of truncation. 
   Preferably, said ratio of the depth of the reflector T to said diameter of the reflector D to is at least 1.4. 
   Preferably, said ratio of the depth of the reflector T to said diameter of the reflector D to is at least 1.7. 
   Preferably, said ratio of the depth of the reflector T to said diameter of the reflector D to is at least 2.0. 
   Preferably, said ratio of the depth of the reflector T to said diameter of the reflector D to is at least 4.0. 
   Preferably, said focal point is located on said optical axis at a location less than 5% of the distance from the vertex to said plane of truncation. 
   Preferably, said focal point is located on said optical axis at a location approximately 2% of the distance from the vertex to said plane of truncation. 
   Preferably, said depth T is approximately 3 inches and said diameter D is approximately 1.7 inches. 
   Preferably, said focal point is located at a distance of approximately 0.06 inches away from said vertex. 
   Preferably, a center point of said light emitting surface is located at a point on said optical axis as close to the vertex as possible but at a location just far enough away from said vertex such that the entire light emitting surface is completely positioned within said reflector member whereby light emitted in a radially outward direction by said light emitting surface is reflected forwardly by said reflector member. 
   Preferably, light emitting surface is generally circular in shape but may be any shape. 
   Preferably, said reflector member has a cross sectional configuration in the form of a parabola in all planes which include the line x=0. 
   Preferably, said light emitting element emits light in forward or sideways directions but not in a rearward direction. 
   Preferably, said light emitting element is a light emitting diode. 
   It is contemplated that the reflector of the present invention may be utilized for a variety of light emitting objects including, but not limited to, flashlights, task lights, head lights for automobiles, track lights, spot lights and various head lamps for individuals such as miners, dentists and doctors, for example, and for various optical instruments such as transits, collimators and the like. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross sectional view showing the inner surface of the reflector of the present invention. 
       FIG. 2  is a cross sectional view showing a portion of the inner surface of the reflector of the present invention with an LED light source positioned too deeply in the reflector. 
       FIG. 3  is a cross sectional view showing a portion of the inner surface of the reflector showing an LED light source properly positioned within the reflector. 
       FIG. 4  shows the head portion and battery carriage for a flashlight formed according to the present invention. 
       FIG. 5  shows the body portion, reflector and front lens of the flashlight of FIG.  4 . 
       FIG. 6  is a side view of the flashlight of  FIGS. 4 and 5  as assembled. 
       FIG. 7  is a cross sectional view of the reflector of the flashlight shown in FIG.  5 . 
       FIG. 8  is a cross sectional view along a plane of truncation showing a reflector having an oval rather than circular configuration. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , the reflector  30  of the present invention is formed in a configuration of a parabola and has a highly reflective inner surface  40 . The vertex V of the parabola is located at the points on a Cartesian coordinate system where X equals 0 and Y equals 0. The focal point FP of the reflector  30  is located along an optical axis  50  and is located at a distance f from the vertex. As shown, the reflector has a diameter D and a depth of T. The end opposite the vertex terminates along a plane of truncation  60  which forms an open end. 
   A light source, in the form of a light emitting diode  10  having a lens  12  and having a light emitting surface  20  is provided such that the center of the light emitting surface  20  is located at the focal point FP as shown. The reflective inner surface  40  is truncated at the vertex end along plane  70  which is co-planer with the light emitting surface  20 . This forms an opening  72  near the vertex which is just large enough for the entire light emitting surface  20  to be contained completely within the inner surface  40  of the reflector  30 . 
   The deep dish or long parabolic reflector has been developed in order to maximize the light output from an LED light source or other light emitting object. Applicants have discovered that the ratio between the depth of the parabolic surface T and the diameter D makes the reflector superior to known devices where a concentrated beam of light is desired. 
   Applicants have discovered that it is desirable to place the LED light source as close as possible to the vertex V thereby keeping the focal length f as short as possible. This principal is explained more fully in  FIGS. 2 and 3 . 
   In  FIG. 2 , an LED light source  10  having a light emitting surface  20  is placed too deep within the inner reflective surface  40  of reflector  30  such that outer portions  22  of the light emitting surface  20  actually extend outside of the parabolic reflector. Because of this, a portion of the light generated by the light emitting surface  22  which is emitted radiantly is not reflected by the inner surface  40  but rather as, is shown by ray of light R 3 , is not captured by the reflective surface  40 . Because of this, all rays of light within an angle “b” are not captured and thus a substantial portion of the light emitted by the light emitting surface  22  is essentially wasted. In  FIG. 2  the focal point FP is closer to the vertex V than is shown in FIG.  3 . 
   In  FIG. 3 , the light emitting surface  20  is placed entirely within the reflective surface  40  of reflector  30 . In this preferred embodiment, outer edge portions  22  of the light emitting surface  20  are fully within the reflective surface. Thus, all rays of light, such as ray R 4  which are emitted radially outward, are reflected parallel to the optical axis  50  as shown. In this case, the opening  72  along the plane of truncation  70  is co-planer with the light emitting surface  20 . In  FIG. 2 , the plane of truncation  70  at the vertex end is not co-planer but rather is higher than the plane of the light emitting surface  22 . 
   Referring back to  FIG. 1 , it will be seen that a certain portion of the light from the LED  10  will pass without being reflected by the reflector  30  directly out of the front open end of the reflector  30  through the plane of truncation  60  as is shown by rays of light R 1  and R 2 . The angle between these two rays is an angle “a” which angle becomes smaller and smaller the deeper the reflector becomes. 
   The general formula for a parabola is x 2 =(4) (f) (y) where f=focus of the parabola. When x is known, y can be calculated by the formula y=x 2 /(4) (f). 
   In the preferred embodiment of the invention, as shown in  FIG. 1  a focus f of 0.06″ is utilized. Using the above formula, the following chart shows what the depth, the diameter and the depth to diameter ratio is for various depths of the reflector. 
   
     
       
             
             
             
           
             
           
             
             
             
           
         
             
                 
             
             
                 
                 
               Depth to 
             
             
               Depth 
               Diameter 
               Diameter Ratio 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               (all numbers are in inches) 
             
           
        
         
             
               1.0416 
               1.000 
               1.0416 
             
             
               1.5000 
               1.200 
               1.2500 
             
             
               2.0000 
               1.386 
               1.443 
             
             
               3.0000 
               1.697 
               1.767 
             
             
               4.1667 
               2.000 
               2.08335 
             
             
               16.667 
               4.000 
               4.16675 
             
             
               37.500 
               6.000 
               6.25 
             
             
                 
             
           
        
       
     
   
   From the foregoing, it can be seen that as the diameter of the plane of truncation increases, the depth of the reflector begins to increase exponentially. Applicants prefer the depth to diameter ratio to be as large as possible but, as can be seen from the above chart, the depth quickly becomes unmanageable for a flashlight as it is unlikely that one would want to carry a flashlight having a reflector over 37″ deep. 
   In the presently preferred embodiment of the invention, a flashlight is produced as shown in  FIGS. 4 ,  5 ,  6  and  7  which has a reflective surface  240  which has a diameter of 1.697″ and a depth of 3.00″. As shown in these figures, the flashlight has an unusual visual appearance as most flashlights have been designed upon a principal of keeping the depth of the reflector relatively short so as not to unnecessarily take up space which could be otherwise be used for batteries and the like. Applicants, on the other hand, have found that utilizing the deep dish reflector provides an extremely efficient and bright beam of concentrated light which is superior to the beams of light generated by shallower reflectors or reflectors which place an LED or other light source at a focal point at a distance further away from the vertex than is absolutely necessary. 
   Referring again to  FIG. 2 , although such an embodiment of the invention is not preferred as it results in an unnecessary loss of light, when the LED is placed closer to the vertex V, the angle “a” decreases. Thus, for example, the angle “a” as shown in  FIG. 1  might be 32.198° whereas the corresponding angle “a” if the LED were moved downwardly as shown in  FIG. 2  might decrease to an angle of 26.435°. Having a narrower angle of dispersion may be desirable in certain cases even with the knowledge that some of the illumination is being wasted. Thus, while not preferred, the present invention still recognizes the utility of the embodiment shown in FIG.  2 . In the example shown in  FIG. 2 , angle “b” would be an angle of 13.774° which would result in a substantial loss of total illumination. 
   Referring briefly to the flashlight shown in  FIGS. 4-7 , a head  120  is provided which includes a switch  122  and a battery carrier  125  adapted to receive batteries  126  which are held in place by springs  128 . A divider  129  in the battery carrier is utilized to provide two different banks of cells which can be utilized to illuminate the LED  210  ( FIG. 7 ) independently of one another. 
   Referring to  FIG. 5 , a body  110  is shown which screws into head portion  120 . A reflector  130  is provided as is a front lens  140 . It will be obvious that depending upon the nature of the inner surface of the reflector  130  that lens  140  would be optional. 
     FIG. 6  shows the flashlight  100  with the head portion  120  attached to the body portion  110 . 
     FIG. 7  shows a cross sectional view of the reflector  130  showing an inner reflective surface  240 , a light emitting diode  210  having a light emitting surface  220  fully contained within the reflective surface  240 . 
     FIG. 8  shows a plane of truncation of an alternate embodiment of the present invention which has a front opening which is not circular but oval. It will be understood by those skilled in the art that various shapes of the opening end could result in a variety of three dimensional shapes to create non-circular beamed shapes. As shown in  FIG. 8 , a first diameter d 1  and a second diameter d 2  are shown. The present invention contemplates a generally deep dish shaped reflector member having a reflective inner surface and having a reflector having a rear vertex and a forward open end and having a depth greater than the average diameter of the forward open end. Thus, an average would be taken of D 1  and D 2  to calculate the average diameter of the forward open end of the reflector of FIG.  8 . 
   While we have shown and described the presently preferred embodiment of our invention, the invention is not limited thereto and may be otherwise variously practiced within the scope of the following claims: