Abstract:
A LED lens assembly comprises a longitudinal rotationally symmetric inner surface contact to at least one LED and a longitudinal rotationally symmetric exterior surface exposure to the air. The half of the longitudinal cross section of the exterior surface constitutes at least three sections. One primary section bounds part of light by longitudinal total internal reflection, one secondary section reflects part of light by transverse total internal reflection and one tertiary section spreads light accordingly. The shape of each section includes straight or curved lines. The surface of each section includes micro structure of a smooth surface, a diffusive surface, a grating surface, a grooving surface, a surface of random gratings, an irregular grooving surface, a random scattering surface, or a surface of photonics crystal. The LED lens assembly further comprises one concave lens on top of the exterior surface.

Description:
BACKGROUND 
       [0001]    The description relates to a LED lens assembly for LED light broadening. 
         [0002]    In some embodiments, the major distributions of light intensities emitting from LEDs (light emitting diode) are limited to a cone region in free space. This property of limited illumination of LEDs is not suitable for general lighting applications. 
         [0003]    To reach omni-directional illumination with LEDs, in one embodiment of LED light bulb, several approaches are proposed. One common method is to place, at least two, LEDs oriented in different directions to cover larger illumination area. Another method employs optical lens to redirect or spread the light from LEDs to wider angles. There are disadvantages in these two methods. The method of placing several LEDs in different orientations causes more manufacturing issues and heat dissipation problems, which increases the manufacturing cost. On the other hand, in most of lens-design arts, the light from LEDs can spin over a wide region, but lose the uniformity. For direct replacement of conventional light bulbs, the LEDs irradiance requires both broadness and uniformity that can be used in the existing lighting fixtures. 
         [0004]    In the present invention, a new LED lens assembly featuring a particular configuration that enables broadening and smoothing the light distributions is proposed. A LED light, bulb with the innovative LED lens assembly in this invention can be easily manufactured and ready for general lighting applications. 
       SUMMARY 
       [0005]    In one respect, in general, the light emitting from LEDs is reflected and refracted through a LED lens assembly into free space. The light distributions in free space are uniformly broadened by a particular shape of the LED lens assembly through proper internal reflections and refractions. 
         [0006]    In one aspect, a LED light assembly is disclosed. The LED lens assembly for broadening LED light distribution includes an inner surface for receiving a plurality of rays emitting from at least one LED chip, and an exterior surface for confining and redirecting the plurality of rays received by the inner surface. The inner surface is in contact with at least one LIED chip and is rotational symmetric about one longitudinal axis. The exterior surface is rotationally symmetric about the longitudinal axis, coaxial with the inner surface. 
         [0007]    In one embodiment, the inner surface covers and touches the top surface of the LED chip closely. 
         [0008]    In one embodiment, a longitudinal cross-section of the exterior surface containing the longitudinal axis of the rotationally symmetric exterior surface includes a mushroom structure, a Y structure, a tree structure, a tower structure, a pillar structure, a tube structure, or a sword structure. 
         [0009]    In one embodiment, a half of the longitudinal cross-section of the rotationally symmetric exterior surface includes at least three sections to constitute the periphery of the half of the longitudinal cross-section. The at least three sections include at least one primary section to bound a portion of the rays received by the inner surface from the LED chip by total internal reflection with a plurality of rays propagating parallel to the longitudinal axis inside the lens assembly; at least one secondary section to receive the bounded longitudinally propagating rays from the primary section to have total internal reflection with a plurality of rays propagating transverse to the longitudinal axis inside the lens assembly; and at least one tertiary section to receive a plurality of rays reflected from the secondary section and transmit a plurality of rays into the air. 
         [0010]    In one embodiment, the primary section transmits laterally a portion of the rays received by the inner surface from the LED chip into the air. 
         [0011]    In one embodiment, the secondary section transmits upwardly a portion of the bounded longitudinally propagating rays from the primary section into the air. 
         [0012]    In one embodiment, a geometric shape of each of the three sections is selected front a group consisting of a straight line, a curve, an arc, a concave structure, and a convex structure. 
         [0013]    In one embodiment, the exterior surface has at least one section, where total internal reflection occurs with light propagating in the direction transverse to the longitudinal axis. 
         [0014]    In one embodiment, the exterior surface has at least one section, where outward transmission occurs with light propagating within an incident angle less than the critical angle of total internal reflection with respect to the section. 
         [0015]    In one embodiment, the exterior surface has at least one section, wherein a regular structure is textured on the surface. 
         [0016]    In one embodiment, the exterior surface has at least one section, wherein an irregular structure is textured on the surface 
         [0017]    In one embodiment, the at least three sections includes at least one primary section to bound a portion of the rays received by the inner surface from the LED chip by total internal reflection with a plurality of rays propagating parallel to the longitudinal axis inside the lens assembly, at least one secondary section to receive the bounded longitudinally propagating rays from the primary section to have total internal reflection with a plurality of rays propagating transverse to the longitudinal axis inside the lens assembly, and at least one tertiary section to receive a plurality of rays reflected from the secondary section and transmit a plurality of rays into the air. 
         [0018]    In one embodiment, the primary section transmits laterally a portion of the rays received by the inner surface from the LED chip into the air. 
         [0019]    In one embodiment, the secondary section transmits upwardly a portion of the hounded longitudinally propagating rays from the primary section into the air. 
         [0020]    In one embodiment, a geometric shape of each of the three sections is selected from a group consisting of a straight line, a curve, an arc, a concave structure, and a convex structure. 
         [0021]    In one embodiment, an arctangent of a mathematical slope of each of the three sections is within a respective scope of: the primary section having a tangent line at each point of a geometric shape, with the arctangent of the slope of the tangent line in the range from 45 to 135 degree; the secondary section having a tangent line at each point of a geometric shape, with the arctangent of the slope of the tangent line in the range from 0 to 90 degree; and the tertiary section having a tangent line at each point of a geometric shape, with the arctangent of the slope of the tangent line in the range from 0 to 180 degree. 
         [0022]    In one embodiment, each of the three sections has a micro structure that corresponds to at least one of a smooth surface, a diffusive surface, a grating surface, a grooving surface, a surface of random gratings, an irregular grooving surface, a random scattering surface, or a surface of photonics crystal. 
         [0023]    In one embodiment, the LED lens assembly further includes a concave lens on top of the exterior surface. The additional concave lens can be placed on the top of the exterior surface to form a closed region between the exterior surface and the concave lens, wherein the index of refraction of the closed region is less than the index of refraction of the LED lens assembly. 
         [0024]    In another aspect of the present invention, a LED light bulb is disclosed. The LED light bulb includes at least one LED chip, a lens assembly, a heat sink, and a transparent shell. The lens assembly includes an inner surface for receiving a plurality of rays emitting from the at least one LED chip, and an exterior surface for confining and redirecting the plurality of rays received by the inner surface. The inner surface is in contact with at least one LED chip and is rotational symmetric about one longitudinal axis. The exterior surface is rotationally symmetric about the longitudinal axis, coaxial with the inner surface. The exterior surface encloses the inner surface with one adjoined circular border line. The heat sink has the LED lens assembly mounted thereon. The transparent shell covers the heat sink. 
         [0025]    In one embodiment, the longitudinal cross-section of the exterior surface containing the longitudinal axis of the rotationally symmetric exterior surface includes a mushroom structure, a Y structure, a tree structure, a tower structure, a pillar structure, a tube structure, or a sword structure. 
         [0026]    In one embodiment, a half of the longitudinal cross-section of the rotationally symmetric exterior surface includes at least three sections to constitute the periphery of the half of the longitudinal cross-section. The at least three sections includes at least one primary section, at least one secondary section, and at least one tertiary section. The at least one primary section is to bound a portion of the rays received by the inner surface from the LED chip by total internal reflection with a plurality of rays propagating parallel to the longitudinal axis inside the LED lens assembly. The at least one secondary section is to receive the bounded longitudinally propagating rays from the primary section to have total internal reflection with a plurality of rays propagating transverse to the longitudinal axis inside the LED lens assembly. The at least one tertiary section is utilized to receive a plurality of rays reflected from the secondary section and transmit a plurality of rays into the air. 
         [0027]    In further another aspect of the present invention, a LED tube lamp is disclosed. The LED tube lamp includes at least two LED chips, at least two LIED lens assemblies, a heat sink and a transparent shell. The at least two LED chips line in one row. Each LED chip is covered by one of the at least two LED lens assemblies. Each of the LED lens assemblies comprises an inner surface for receiving a plurality of rays emitting from one LED chip, and an exterior surface for confining and redirecting the plurality of rays received by the inner surface. The inner surface is in contact with one LED chip and is rotational symmetric about one longitudinal axis. The exterior surface is rotationally symmetric about the longitudinal axis, coaxial with the inner surface. The exterior surface encloses the inner surface with one adjoined circular border line. The heat sink has the LED chip and the LED lens assembly mounted thereon. The transparent shell covers the heat sink. 
         [0028]    In further another aspect of the present invention, a LED round lamp is disclosed. The LED round lamp includes at least three LED chips, at least three LED lens assemblies, a heat sink and a transparent shell. The at least three LED chips line in one circle or ellipse. Each LED chip is covered by one of the at least three LED lens assemblies. Each of the at least three LED lens assemblies comprises an inner surface for receiving, a plurality of rays emitting from one LED chip, and an exterior surface for confining and redirecting the plurality of rays received by the inner surface. The inner surface is in contact with one LED chip and is rotational symmetric about one longitudinal axis. The exterior surface is rotationally symmetric about the longitudinal axis, coaxial with the inner surface. The exterior surface encloses the inner surface with one adjoined circular border line. The heat sink has the LED chip and the LED lens assembly mounted thereon. The transparent shell covers the heat sink. 
         [0029]    Advantage of the present LED lens assembly is to provide wide angle illumination in free space with rather good uniformity. The configuration of the LED light bulb and light tube are simple and can be easily fabricated. Further objects and advantages of this invention will be apparent from the following detailed description with accompanied drawings. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0030]      FIG. 1  shows a LED lens assembly according to a preferred embodiment of the present invention.) 
           [0031]      FIGS. 2   a  to  2   d  are sectional views of the LED lens assembly in  FIG. 1 . 
           [0032]      FIG. 3  is a sectional view of a LED lens assembly according to another preferred embodiment of the present invention. 
           [0033]      FIG. 4   a  is a sectional view of a LED lens assembly according to further another preferred embodiment of the present invention. 
           [0034]      FIG. 4   b  is a sectional view of a LED lens assembly according to farther another preferred embodiment of the invention. 
           [0035]      FIG. 5  is a sectional view of a LED lens assembly according to further another preferred embodiment of the present invention. 
           [0036]      FIG. 6  is a sectional view of a LED lens assembly according to further another preferred embodiment of the present invention. 
           [0037]      FIG. 7   a  shows a LED lens assembly according to a preferred embodiment of the present invention. 
           [0038]      FIG. 7   b  is a sectional view of the LED lens assembly in  FIG. 7   a.    
           [0039]      FIG. 8  shows a LED light bulb with LED lens assembly according to a preferred embodiment of the present invention. 
           [0040]      FIG. 9  shows a LED light bulb with LED lens assembly according to another preferred embodiment of the present invention. 
           [0041]      FIG. 10  shows a LED tube lamp with LED lens assembly according to a preferred embodiment of the present invention. 
           [0042]      FIG. 11  shows a LED round lamp with LED lens assembly according to a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]      FIG. 1  shows a LED lens assembly  100  with wide angle of illumination according to one embodiment of the present invention.  FIG. 2   a  is the sectional view of  FIG. 1 , wherein the LED lens assembly  100  receives and spreads the rays  301  emitting from LEDs  1  into free space. The LED lens assembly  100  includes an inner surface  101  and an exterior surface  200 . The exterior surface  200  includes a primary section  201 , secondary sections  202 ,  203 ,  204 , and tertiary sections  205 ,  206  as shown in the upright window, which is rotationally symmetric about one longitudinal axis  110 . Due to this symmetric property, figure illustration with half of the cross section of the exterior surface  200  will represent the whole configuration in the rest discussion of the entire description. As shown in  FIG. 2   b , the upward emitting rays  301  are received by inner surface  101  and become the transmission rays  302 . Rays  302  propagate vertically and are bounded by the primary section  201  of the exterior surface  200 , wherein total internal reflections  401  occurs that makes rays  302  propagate along the longitudinal axis  110 . In  FIG. 2   c , part of rays  302 , say ray  303 , reaches and hits the secondary sections  202 ,  203 , and  204  of exterior surface  200 , where total internal reflections occur on points  402 ,  403  and  404  such that the reflected rays  3032 ,  3033  and  3034  propagate outwardly transverse to the longitudinal axis  110 , pass through the tertiary sections  205 ,  206  and become transmission rays  30321 ,  30331  and  30341  in the air. In  FIG. 2   c , part of rays  302 , say rays  304 , reaches the secondary sections  202 ,  203 ,  204  and the tertiary section  205  of exterior surface  200  which directly refract and transmit rays  3042 ,  3043 ,  3044  and  3045  into the air, respectively. Through the above various reflections and refractions, the transmitting rays  30321 ,  30331 ,  30341 ,  3042 ,  3043 ,  3044  and  3045  in  FIG. 2   c  and  FIG. 2   d  constitute the widely distributed light in free space by the LED lens assembly  100  designed in the present invention. 
         [0044]    The degree of broadness of light distribution, not uniformity, can be decided by the amount of the transverse total internal reflections, for embodiment, the numbers of the reflection points, like  402 ,  403 , and  404  on the exterior surface  200  of LED lens assembly  100  in  FIG. 2   c .  FIG. 3  shows another embodiment of the present invention, similar to  FIG. 2   a,  except with one additional secondary concave section  2007  on the exterior surface  2000  and different shapes of lens sections  2001 ,  2002 ,  2003 ,  2004 ,  2005 , and  2006  in the LED lens assembly  1000 . More rays  3037  are totally reflected transverse-downwardly inside the LED lens assembly  1000 , which cause more rays  30371  transmitting out of the LED lens assembly  1001  downwardly such that the light distribution in free space is further broadened. The determination of light distribution in wider angles is based on the principle of how many secondary concave sections are designed on the exterior surface  2000 , which decides how much light amount will be redistributed outwardly and downwardly in free space. Meanwhile, the particular shape of each concave section determines the uniformity. 
         [0045]    The main spirit of present invention is according to three schemes performed by the primary, secondary, and tertiary sections of exterior surface  200  in  FIG. 2   a . First, as shown in  FIG. 2   a , the primary section  201  promotes the planar wave front LEDs rays  301  to curvier wave front rays  302  inside the exterior surface section  201  through longitudinal total internal reflection  401 . Second, as shown in  FIG. 2   b , part of rays  302 , rays  303 , are redirected outwardly by transverse total internal reflection  402 ,  403 ,  404  on the secondary surface sections  202 ,  203 ,  204  and become rays  3032 ,  3033 ,  3034 . Third, through various refractions, together by the secondary sections  202 ,  203 ,  204  shown in  FIG. 2   d  to have output rays  3042 ,  3043 ,  3044 ; and by the tertiary sections  205 ,  206  shown in  FIG. 2   c  to have output rays  30321 ,  30331 ,  30341  and  3045  respectively, the uniformity of the light distribution in the air can be greatly improved by all contributions from each section with a particular shape. 
         [0046]    To achieve omni-directional illumination, one particular embodiment is illustrated in  FIG. 4   a . The lens  4000  includes one inner surface  4001  and one exterior surface  5000  which are rotationally symmetric about one axis  4100 . Similar to the previous lens  100  in  FIG. 2   a  and lens  1000  in  FIG. 3 , the exterior surface  5000  has primary section  5001 , secondary sections,  5002 ,  5003 ,  5004 ,  5005 ,  5006 ,  5007 ,  5008 , and tertiary sections  5009 ,  5010 . The slopes of the tangent lines to all points on the boundaries of the secondary sections,  5002 ,  5003 ,  5004 ,  5005 ,  5006 ,  5007 ,  5008  in  FIG. 4   a  all fall in the scope of 0 to 1. The design of such a shape of the lens  4000  is to match the light distribution diagram from incandescent lamp in free space as close as possible.  FIG. 4   b  shows another embodiment of a lens structure very similar to  FIG. 4   a.  In FIG.  4   b . the lens  4500  has the inner surface  4001  and the primary section  5001  that embed the LED  001 , which are different from those  4001  and  5001  in  FIG. 4   a . Another feature of lens  4500  in  FIG. 4   b  is the tertiary section  5009  that extends down below the inner face  4001 , which makes the lens  4500  encapsulate the whole LED  001  inside. 
         [0047]    Another scheme to enhance the broadness of illumination is to add various textures on the various sections of the exterior surface  200  in  FIG. 2   a.    FIG. 5  illustrates one embodiment of LED lens assembly  500 . There are 4 sections,  601 ,  602 ,  603 , and  604  on exterior surface  600  as shown in the window, wherein section  603  is textured with the grooving  6031 . In the figure, ray  302  becomes ray  305  by total internal reflection occurred at point  401 , which is further randomly reflected by the grooving structure  6031  on section  603  and becomes ray  3051 . Ray  3051  later becomes the transmission ray  3052  in the air. Due to various rays  305  with different incident angles on section  603 , the transmission rays  3052  behave randomly distributed in all directions such that the light distribution get broadening and smoothing. 
         [0048]      FIG. 6  shows another embodiment, the LED lens assembly  700 , with broadness enhancement of light distribution similar to the embodiment of LED lens assembly  500  in  FIG. 5 . As indicated in the window, there are 4 sections  801 ,  802 ,  803 , and  804  on exterior surface  800  in the LED lens assembly  700 . Part of the bounded rays  306 , say ray  3061 , hits the grooving structure  8031  on surface section  803  and becomes randomly reflected ray  30611 . Ray  30611  later becomes the transmitting ray  30612  in the air. Part of the bounded rays  306 , say, ray  3062  propagates directly upward and reaches surface section  804 . Ray  3062  passes through surface  804  and becomes the diffracted ray  30621  in the air governed by Snell&#39;s law. All exterior surface sections  801 ,  802 ,  803 ,  804  are free to choose different textures if necessary. 
         [0049]    The emitting light can spread out even widely and smoothly with an additional lens attached.  FIG. 7   a  illustrates the combination of the lens  100  in  FIG. 2   a  with another lens  900  to form a LED lens assembly  100900 . The LED lens assembly  900  is also rotationally symmetric about the longitudinal axis  110  and the surface of lens  900  is divided in 3 sections,  901 ,  902  and  903  as seen in the window of  FIG. 7   b . In  FIG. 7   b , ray  3042  emerging from the LED lens assembly  100  incidents on surface section  901  and becomes the diffracted ray  30421  inside the LED lens assembly  900 . Ray  30421  later becomes the transmitting ray  30422  in the air with larger diffraction angle by Snell&#39;s law of diffraction. Similarly, ray  3043  will go through the same process and becomes ray  30431  inside the lens  900  and ray  30432  in the air. With attached LED lens assembly  900 , light in the free space will distribute even more smoothly. 
         [0050]    With the present invention,  FIG. 8  shows a LED light bulb assembly  8000  with the LED lens assembly  100900  in  FIG. 7   a , one heat sink  8001 , and one transparent shell  8002 .  FIG. 9  shows another embodiment of LED light bulb  8200  with the LED lens assembly  4000  in  FIG. 4   a , one heat sink  8201 , and one transparent shell  8202 . The heat sink  8201  includes a shape of a round cup  82011  with a lifted, flat round top surface  82012 . The LED chip and lens assembly  4000  are mounted on the top surface  82012 . The transparent shell  8202  covers the heat sink  8201 .  FIG. 10  shows one embodiment of LED tube lamp  8400  using five LED chips and LED lens assemblies  4500  in  FIG. 4   b . The LED lamp tube  8400  also includes one heat sink  8401  and one transparent shell  8402 . The heat sink  8401  includes a shape of a long strip with a flat top surface. The LED chip and the LED lens assembly are mounted on the top surface of heat sink  8401 . The transparent shell  8402  covers the heat sink  8401 , Another LED round lamp  8600  is illustrated in  FIG. 11 . Round lamp  8600  includes three LED chips and LED lens assemblies  4500  as described in  FIG. 4   a , lining in one circle, one heat sink  8061  and one transparent shell  8062 . The heat sink  8601  includes a shape of a round cup with a round top surface The LED chip and the LED lens assembly are mounted on the top surface of heat sink  8601 . The transparent shell  8602  covers the heat sink  8601 . 
         [0051]    A number of embodiments of the present invention have been described and illustrated. Nevertheless, the scope of the invention is not intended to be limited thereby, and such other modifications, implementations and applications are particularly reserved especially as they fall within the breadth and scope of the claims here appended.