Abstract:
An adapter lens includes an inner converging lens part; a convex light output region; a front conical light output region; an outer reflector part; a rearwardly open blind hole defining surface including a flat base surface and a frustoconical side surface that together define a light incidence region and a frustoconical hole having an inner end diameter, an outer end diameter, and allowing for longitudinal movement therein of a LED light source along an optical axis of the adapter lens within the frustoconical hole for changing a light cone emitted from the adapter lens. The adapter lens has a height H and a maximum diameter MD, and the ratio of the height H to the maximum diameter MD is greater than 0.5.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates, in general, to optical lenses, and, in particular, to optical lenses for flashlights. 
       BACKGROUND OF THE INVENTION 
       [0002]    U.S. Pat. No. 7,461,960 to Opolka, et al. (“Opolka Lens”) discloses a LED illumination module with a rotationally symmetrical, one-piece, light-transparent adapter lens that has an inner converging lens part and an outer reflector part and a rearwardly open blind hole that is defined by a beveled or frustoconical surface with arcuate profile and a convex base surface and that has an inner diameter allowing for axial movement of a LED body within the opening along the optical axis of the adapter lens. The LED illumination module allows longitudinal and axial movement of the whole arrangement consisting of the LED glass body and the base in the blind hole-like bore, so that, by a relative movement of the LED to the blind hole-like bore along the optical axis, different emission characteristics with different cone angles of the light emission pencils can be variably set. 
       SUMMARY OF THE INVENTION 
       [0003]    An aspect of the invention involves an adapter lens including an inner converging lens part; a convex light output region; a front conical light output region; an outer reflector part; a rearwardly open blind hole defining surface including a flat base surface and a frustoconical side surface that together define a light incidence region and a frustoconical hole having an inner end diameter, an outer end diameter, and allowing for longitudinal movement therein of a LED light source along an optical axis of the adapter lens within the frustoconical hole for changing a light cone emitted from the adapter lens caused by light rays from the LED light source refracted by the inner converging lens part, reflected by the outer reflector part, and transmitted through the convex light output region and front conical light output region, wherein the adapter lens has a height H and a maximum diameter MD, and the ratio of the height H to the maximum diameter MD is greater than 0.5 
         [0004]    One or more implementations of the aspect of the invention described immediately above include one or more of the following: the ratio of the height H to the maximum diameter MD is greater than 0.55; the ratio of the height H to the maximum diameter MD is greater than 0.6; the frustoconical hole has a depth D, and the ratio of the maximum diameter MD to depth D is less than 5.3; the frustoconical hole has a depth D, and the ratio of the maximum diameter MD to depth D is less than 4.9; the frustoconical hole has a depth D, and the ratio of the maximum diameter MD to depth D is less than 4.5; the frustoconical hole has a depth D, and the ratio of the maximum diameter MD to depth D is less than 4.1; the front conical light output region includes a curved annular front wall that radiates from the convex light output region and curves upwardly and outwardly in a non-linear configuration; the outer reflector part includes a curved outer annular surface that radiates from the frustoconical hole and curves upwardly and outwardly in a non-linear configuration; the front conical light output region extends at a tilt angle a of less than 35 degrees relative to a perpendicular from the optical axis; the front conical light output region extends at a tilt angle a of less than 32 degrees relative to a perpendicular from the optical axis; the front conical light output region extends at a tilt angle a of less than 29 degrees relative to a perpendicular from the optical axis; the convex light output region has an apex angle 0 of less than 38 degrees relative to a perpendicular from the optical axis; the convex light output region has an apex angle 0 of less than 32 degrees relative to a perpendicular from the optical axis; the convex light output region has an apex angle 0 of less than 26 degrees relative to a perpendicular from the optical axis; the convex light output region has a depth T, and the ratio of the maximum diameter MD to depth T is more than 7.0; the convex light output region has a depth T, and the ratio of the maximum diameter MD to depth T is more than 8.5; the convex light output region has a depth T, and the ratio of the maximum diameter MD to depth T is more than 10.0; the front conical light output region terminates into an outwardly extending ledge that protrudes radially outwardly from the front conical light output region; the adapter lens includes a length H and the total length of the adapter lens is greater than 17 mm; the adapter lens includes a length H and the total length of the adapter lens is greater than 20 mm; the adapter lens includes a length H and the total length of the adapter lens is greater than 23 mm; the inner converging lens part includes a diameter d and the frustoconical hole includes a largest diameter LD, and the diameter d is more than 1 mm larger than the largest diameter LD; the inner converging lens includes a thickness T and the adapter lens has a length H, and the ratio of the thickness T to the length H is less than 0.55; the inner converging lens includes a thickness T and the adapter lens has a length H, and the ratio of the thickness T to the length H is less than 0.4; the inner converging lens includes a thickness T and the adapter lens has a length H, and the ratio of the thickness T to the length H is less than 0.25; the inner converging lens part includes a diameter d and the adapter lens includes a maximum diameter MD, and the ratio between the diameter d to the maximum diameter MD is less than 0.5; the inner converging lens part includes a diameter d and the adapter lens includes a maximum diameter MD, and the ratio between the diameter d to the maximum diameter MD is less than 0.46; the inner converging lens part includes a diameter d and the adapter lens includes a maximum diameter MD, and the ratio between the diameter d to the maximum diameter MD is less than 0.42. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a cross sectional view of a lens in accordance with an embodiment of the invention; 
           [0006]      FIGS. 2A-2H  are front perspective, rear perspective, rear elevational, front elevational, bottom plan, top plan, left elevational, and right elevational views of the lens of  FIG. 1 ; 
           [0007]      FIG. 3  is a right elevational view of the lens of  FIG. 1  and shows a tilt angle a and an apex angle β of the lens; 
           [0008]      FIG. 4  is a cross sectional view of the lens similar to that shown in  FIG. 1  and shows the emission characteristics of the lens when the LED is disposed at an entrance of a rearward open blind hole of the lens; and 
           [0009]      FIG. 5  is a cross sectional view of the lens similar to that shown in  FIG. 1  and shows the emission characteristics of the lens when the LED is disposed in the rearward open blind hole of the lens, near a flat base surface of the lens. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0010]    Turning now to the drawings, in which like reference characters indicate corresponding elements throughout the several views, an adapter lens  100  for a flashlight is disclosed. In alternative applications, the adapter lens  100  is used in other applications, other than for a flashlight. The lens  100  includes a rearward open frustoconical blind hole  110 , a frustoconical side surface (light incidence region)  120 , a flat base surface  130 , an inner converging lens  140 , a convex light output region  150 , a reflector part  160 , an outer annular surface  170  with a curved outer annular surface  175  that radiates from the frustoconical hole  110  and curves upwardly and outwardly in a non-linear configuration, a front conical light output region  180  with a curved annular front wall  185  that radiates from the convex light output region  150  and curves upwardly and outwardly in a non-linear configuration, an outwardly extending/protruding ledge  188  with an edge  190  for mounting, an optical axis  200 , a front edge surface  210 , a rear edge surface  220 , and a LED light source  230  that moves in the direction of arrow  240  inside rearward open blind hole  110 . The overalll structural characeteristics of the lens  100  allows the lens  100  to outperform flashlight adapter lenses in the past because the lens  100  provides an ideal even, uniform hot spot when focused in, but at the same time, provides a very even full light without dark circles when focused out to flood. 
         [0011]    The adapter lens  100  acts as a lens body. The rearward open blind hole  110  is defined by the frustoconical side surface  120  and the flat base surface  130  all centered on the optical axis  200 . The flat base surface  130  is also the light incidence region of the inner converging lens  140 , which includes the convex light output region  150  on a front face. The flat base surface  130  allows the adapter lens  100  to provide a bright hotspot beam when the beam angle is narrow (e.g.,  FIG. 4 ) and create an even, light beam circle, reducing most dark spots, when the beam angle is wide (e.g.,  FIG. 5 ). The converging lens  140  is surrounded by the reflector part  160  that is essentially formed by the surface  120  as light incidence region as well as by the outer annular surface  170 , which totally reflects light, and by the front conical light output region  180 . As shown, the reflector part  160  can also have the annular extended lens edge  190  for mounting the adapter lens  100  in the head of a flashlight. The annular extended lens edge  190  extends substantially parallel to the optical axis  200 . Front edge surface  210  and rear edge surface  220  extend perpendicular to the optical axis  200 . 
         [0012]    The rearward conical open blind is so wide or the diameter of the opening is so large that the LED  230  can be moved along the optical axis  200  in the direction of the double arrow  240 . 
         [0013]    Different emission characteristics are shown in  FIGS. 4 and 5 . A relatively narrow beam is achieved with a setting according to  FIG. 4 , when the LED  230  is disposed at the entrance of the rearward open blind hole  110  of the lens  100 . The light emitted by the LED  230  is refracted when it meets the flat base surface/light incidence region  130  and, after a second light refraction, leaves the inner converging lens  140  through the convex light output region  150 . The frustoconical side surface  120  refracts the edge rays onto the outer annual surfaces  170 , where they are totally reflected and finally leave to the front after refraction from the front conical light output region  180 . The emission characteristic obtained with the adapter lens  100  and the LED  230  in the shown position, consists in a relatively narrow light cone with small cone angle. With the relatively narrow light cone, the structural characteristics of the lens  100  enables the lens  100  to provide a much more even, uniform light compared to the Opolka Lens and at the same time creating a bright “hotspot”. Prior lenses with the LED or light source in this position created many dark rings in parts of the light beam. 
         [0014]    In the position of the LED  230  according to  FIG. 5 , in which the LED  230  is moved further forward into the hole  110  (near the flat base surface  130  or closer to the flat base surface  130  than the rear edge surface  220 ), the light rays refracted by the inner converging lens  140  diverge and the light rays deriving from the reflector part  160  converge, which is due to different calculation and reflection angles. The emission characteristic obtained with the adapter lens  100  and the LED  230  in the shown position, consists in a relatively wide light cone with large cone angle. With the relatively wide light cone, the structural characteristics of the lens  100  enables the lens  100  to provide a much more even, uniform light compared to the Opolka Lens. Prior lenses with the LED or light source in this position created many dark rings in parts of the light beam. 
         [0015]    As shown in  FIG. 3 , the front conical light output region  180  extends at a tilt angle a of 25.33 degrees relative to a perpendicular  240  from the optical axis  200 . In a preferred embodiment of the invention, the front conical light output region  180  extends at a tilt angle a of more than 25 degrees and less than 35 degrees relative to a perpendicular from the optical axis  200 . In a more preferred embodiment; the front conical light output region  180  extends at a tilt angle a of less than 32 degrees relative to a perpendicular from the optical axis  200 . In a most preferred embodiment, the front conical light output region  180  extends at a tilt angle a of less than 29 degrees relative to a perpendicular from the optical axis  200 . 
         [0016]    In addition, the forwardly directed convex light output region  150  is shown with an apex angle β of 20.2 degrees. In a preferred embodiment of the invention, the convex light output region  150  has an apex angle β of less than 38 degrees relative to a perpendicular from the optical axis  200 . In a more preferred embodiment of the invention, the convex light output region  150  has an apex angle β of less than 32 degrees relative to a perpendicular from the optical axis  200 . In a most preferred embodiment of the invention, the convex light output region  150  has an apex angle β of less than 26 degrees relative to a perpendicular from the optical axis  200 . 
         [0017]    The adapter lens  100  has a maximum diameter MD and a length H, and the ratio of the length H of the adapter lens  100  to its maximum diameter MD is preferably 0.50-0.62. In an exemplary embodiment, the ratio of the length H of the adapter lens  100  to its maximum diameter MD is greater than 0.5. In more preferred embodiment, the adapter lens  100  has a maximum diameter MD and a length H, and the ratio of the length H of the adapter lens  100  to its maximum diameter MD is greater than 0.55. In a most preferred embodiment, the adapter lens  100  has a maximum diameter MD and a length H, and the ratio of the length H of the adapter lens  100  to its maximum diameter MD is greater than 0.6. 
         [0018]    In an embodiment of the invention, the frustoconical hole has a depth D, and the ratio of the maximum diameter MD to depth D is less than 5.3. In more preferred embodiment, the frustoconical hole has a depth D, and the ratio of the maximum diameter MD to depth D is less than 4.9. In a still more preferred embodiment, the frustoconical hole has a depth D, and the ratio of the maximum diameter MD to depth D is less than 4.5. In a most preferred embodiment, the frustoconical hole has a depth D, and the ratio of the maximum diameter MD to depth D is less than 4.1. 
         [0019]    In an embodiment of the invention, the convex light output region  150  has a thickness/depth T, and the ratio of the maximum diameter MD to depth T is more than 7.0. In more preferred embodiment, the convex light output region  150  has a depth T, and the ratio of the maximum diameter MD to depth T is more than 8.5. In a most preferred embodiment, the convex light output region has a depth T, and the ratio of the maximum diameter MD to depth T is more than 10.0. 
         [0020]    The lens  100  preferably has a length H of 12-25 mm. 
         [0021]    In a 40 mm lens embodiment of the invention, the adapter lens includes a length H of 25 mm. In a preferred embodiment, the total length of the adapter lens is greater than 17 mm. In more preferred embodiment, the adapter lens includes a length H and the total length of the adapter lens is greater than 20 mm. In a most preferred embodiment, the adapter lens includes a length H and the total length of the adapter lens is greater than 23 mm. 
         [0022]    In a 30 mm lens embodiment of the invention, the adapter lens includes a length H of 15.5 mm. In a preferred embodiment, the total length of the adapter lens is greater than 12 mm. In more preferred embodiment, the adapter lens includes a length H and the total length of the adapter lens is greater than 13 mm. In a most preferred embodiment, the adapter lens includes a length H and the total length of the adapter lens is greater than 14 mm. 
         [0023]    In an embodiment of the invention, the inner converging lens part  140  includes a diameter d and the frustoconical hole  110  includes a largest diameter LD, and the diameter d is more than 1 mm larger than the largest diameter LD. 
         [0024]    In an embodiment of the invention, the inner converging lens  140  includes a thickness T and the adapter lens  100  has a length H, and the ratio of the thickness T to the length H is less than 0.55. In more preferred embodiment, the inner converging lens  140  includes a thickness T and the adapter lens  100  has a length H, and the ratio of the thickness T to the length H is less than 0.4. In a most preferred embodiment, the inner converging lens  140  includes a thickness T and the adapter lens  100  has a length H, and the ratio of the thickness T to the length H is less than 0.25. 
         [0025]    In an embodiment of the invention, the inner converging lens part  140  includes a diameter d and the adapter lens  100  includes a maximum diameter MD, and the ratio between the diameter d to the maximum diameter MD is 0.4-0.52. In a preferred embodiment, the ratio between the diameter d to the maximum diameter MD is less than 0.5. In more preferred embodiment, the inner converging lens part  140  includes a diameter d and the adapter lens  100  includes a maximum diameter MD, and the ratio between the diameter d to the maximum diameter MD is less than 0.46. In a most preferred embodiment, the inner converging lens part  140  includes a diameter d and the adapter lens  100  includes a maximum diameter MD, and the ratio between the diameter d to the maximum diameter MD is less than 0.42. 
         [0026]    In an embodiment of the invention, the ratio of the thickness T of the inner converging lens  140  to the length H of the adapter lens  100  is 0.15-0.60. In a preferred embodiment, the ratio of the thickness T of the inner converging lens  140  to the length H of the adapter lens  100  is less than 0.6. In a more preferred embodiment, the ratio of the thickness T of the inner converging lens  140  to the length H of the adapter lens  100  is less than 0.45. In a most preferred embodiment, the ratio of the thickness T of the inner converging lens  140  to the length H of the adapter lens  100  is less than 0.30. 
         [0027]    While illustrative embodiments of the invention are disclosed herein, it will be appreciated that numerous modifications and other embodiments can be devised by those skilled in the art. Features of the embodiments described herein, can be combined, separated, interchanged, and/or rearranged to generate other embodiments. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments that come within the spirit and scope of the present invention.