Abstract:
A lens has a first, second and third optical region. The first, second and third optical region are arranged in sequential order. Space angle defined between each first, second and third optical region, and an optical axis of the lens are different from each other. An LED light module, which has an LED chip and the lens is also provided. The light emitted from the LED chip passes the reflecting surface and refractive surface and radiates from a top of the lens.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Taiwan Patent Application No. 103128380 filed on Aug. 19, 2014, the contents of which are incorporated by reference herein. 
       FIELD 
       [0002]    The subject matter herein generally relates to an LED module and a lens of the LED module. 
       BACKGROUND 
       [0003]    Generally, a light emitting diode (LED) includes an LED chip and an encapsulating layer covering the LED chip. The LED generally generates a smooth round light field with a radiation angle of 120 degrees (i.e. ±60 degrees). However, the light emitted from the LED still has a bigger angle relatively to the optical axis. the light intensity concentrated at a center of the LED is not strong enough. The LED cannot be used in special place which needs a smaller angle and strong concentrated light, such as engraving machine, cutting tools and product display ark etc. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
           [0005]      FIG. 1  is an isometric view of an LED module of the present disclosure. 
           [0006]      FIG. 2  is a cross sectional view of the LED module of  FIG. 1 , taken along II-II line thereof. 
           [0007]      FIG. 3  is a light path diagram of the LED module. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0008]    It will be appreciated that for simplicity and clarity of illustration, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure. The description is not to be considered as limiting the scope of the embodiments described herein. 
         [0009]    Several definitions that apply throughout this disclosure will now be presented. The term “comprising” means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in a so-described combination, group, series and the like. 
         [0010]    Referring to  FIGS. 1-2 , an LED module of the present disclosure includes an LED chip  200  and a lens  100  cooperating with the LED chip  200 . 
         [0011]    Referring also to  FIG. 3 , the lens  100  includes a main portion  110 , an extending portion  120  protruding from a central portion of a top end of the main portion  110 , and a light concentrating portion  130  protruding from a central portion of a top end of the extending portion  120 . The lens  100  also has an optical axis  150 . The optical axis  150  is at a radial center of the lens  100 . The main portion  110  the extending portion  120  and the concentrating portion  130  are coaxial and are rotational symmetric about the optical axis  150 . A placing point  201  intersecting with the optical axis  150  and a bottom of the lens  100  is defined. 
         [0012]    The main portion  110  has a shape of frustum. A diameter of the main portion  110  increases from bottom to top. The main portion  110  includes a first inclining face  111  and a first top face  112  connected with a top end of the first inclining face  111 . 
         [0013]    The extending portion  120  has a shape of the frustum. A diameter of the extending portion  120  increases from bottom end connecting with the main portion  110 , towards top end of the extending portion  120 . The diameter of the bottom end of the protruding portion  120  is equal to that of the top end of the main portion  110 . The protruding portion  120  includes a second inclining face  121  and a second top face  122  connecting with a top end of the second inclining face  121 . The first top face  112  and the second inclining face  121  intersect to form a circular edge shown in diametric cross section of the lens  100  to form first intersection points  113 . The first intersection points  113  are symmetrical about the optical axis  150  in diametric cross section of the lens  100 . The first top face  112  is parallel with the second top face  122 . The diameter of the second top face  122  is smaller than that of the first top face  112 . 
         [0014]    The light concentrating portion  130  is arc-shaped and convex. The concentrating portion  130  has an outer face  131  connected with the second top face  122 . The light concentrating portion  130  gathers the light emitted from the LED chip  200 . 
         [0015]    The lens  100  have a first cavity  10  and a second cavity  20 , configured along the optical axis  150  and from the bottom end to the top end of the main portion  110 , a third cavity  30  connects the second cavity and configures towards the extending portion  120 . The first cavity  10 , the second cavity  20  and the third cavity  30  are through along the optical axis  150  and are rotational symmetric about the optical axis  150 . 
         [0016]    The first cavity  10  is frusto-conical, and is bounded by a first inner face  11 . A diametric cross view of the first cavity  10  has a trapezoidal-shape. The diameter of the first cavity  10  decreases from the top end connected with the second cavity  20 , towards a bottom end of the main portion  110 . The LED chip  200  is received in the first cavity  10 , and is posited at the placing point  201 . 
         [0017]    The second cavity  20  is defined by a second inner face  22 . The second inner face  22  extends from the top end of the first inner face  11 . The second inner face  22  is defined on a partial sphere with a core at the placing point  201 . The diameter of the bottom end of the cavity  20  is equal to that of the top end of the first cavity  10 . The second inner face  22  and the first inner face  11  intersect to form a circular edge shown in diametric cross section of the lens  100  to form second intersections points  12 . The second intersections points  12  are symmetrical about the optical axis  150  in the diametric cross section of the lens  100 . 
         [0018]    The third cavity  30  is defined by a third inner face  31  and a fourth inner face  32 . The third inner face  31  extends upwardly from the top end of the second inner face  22 , and away from the optical axis  150 . The fourth inner face  32  connects with a top end of the third inner face  31 , extends closely the optical axis  150  and towards the first cavity  10 . The diameter of the bottom end of the third cavity  30  is equal to that of the top end of the second cavity  20 . The third inner face  31  and the second inner face  22  intersect to form a circular edge shown in diametric cross section of the lens  100  to form third intersection points  23 . The third intersection points  23  are symmetrical about the optical axis  150  in the diametric cross section of the lens  100 . The third inner face  31  and the fourth inner face  32  intersect to form a circular edge shown in diametric cross section of the lens  100  to form fourth intersection points  34 . The fourth intersection points  34  are symmetrical about the optical axis  150  in diametric cross section of the lens  100 . 
         [0019]    As shown in  FIG. 3 , at a side of the optical axis  150  of the diametric cross section of the lens  100 , the fourth intersection points  34  and the placing point  201  cooperatively define an imaginary first line  202 ; the first intersection points  113 , the second intersection points  12  and the placing point  201  cooperatively define a imaginary second line  203 ; 
         [0020]    The lens  100  also defines a plurality of first, second and third optical regions A, B and C, arranged from the top end of the lens  100  towards the bottom end of the lens  100 . The imaginary first line  202  projects around the optical axis  150  to form a first conical area. The first conical area located in the lens  100  defines the first optical region A. The imaginary second line  203  projects around the optical axis  150  to form a second conical area. The second conical area located except the first optical region A in the lens  100  defines the second optical region B. The third optical region C is defined between the second conical area and the bottom end of the lens  100 . An angle defined between the optical axis  150  and a imaginary line defined between the placing point  201  and a point within the second optical region B, is larger than an angle defined between the optical axis  150  and a imaginary line defined between the placing point  201  and a point within the first optical region A. An angle defined between the optical axis  150  and a imaginary line defined between the placing point  201  and a point within the third optical region C, is larger than an angle defined between the optical axis  150  and a imaginary line defined between the placing point  201  and a point within the second optical region B. 
         [0021]    In this disclosure, an angle defined between the optical axis  150  and the third inner face  31  is larger than an angle defined between the optical axis  150  and the first inner face  11 ; an angle defined between the optical axis  150  and the second inclining face  121  is larger than an angle defined between the optical axis  150  and the first inclining face  111 . The outer face  131  is located opposite at the fourth inner face  32 . A focus of the light concentrating portion  130  is posited at the placing point  201 . The third inner face  31 , the first inner face  11 , the outer face  131  and the fourth inner face  32  refract properly the light emitted from the LED chip  200 . The second inclining face  121  and the first inclining face  111  reflect properly the light emitted from the LED chip  200 . Because the second inner face  22  is defined on a partial sphere with a core at the placing point  201 , so the second inner face  22  do not change the path of the light emitted from the LED chip  200 . 
         [0022]    The light emitted from the LED chip  200  having a different radiating angle relative to the optical axis  150  respectively enters the first, second and third optical region A, B and C. Part of light enters the first optical region A, the light is refracted by the fourth inner face  32 , the outer face  131  and part of the second top face  122  to exit from the top end of the lens  100 . Part of light enters the second optical region B, the light is firstly refracted by the third inner face  31  or traverses the second inner face  22 , and then is reflected by the second inclining face  121  to exit from the top end of the lens  100 . The light enters the third optical region C, the light is refracted by the first inner face  11 , and is reflected by the first inclining face  111  to exit from the top end of the lens  100 . The light emitted by the LED chip  200  enters the first, second and third optical regions A, B and C. The original light path of the light is changed by the lens  100  to gather the light to exit towards the top end of the lens  100 . So the light exited from the lens  100  has small angle relative to the optical axis  100  and has great intensity around the optical axis  150 . 
         [0023]    The embodiments shown and described above are only examples. Many details are often found in the art such as the other features of an LED module and lens mounted thereon. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, including in matters of shape, size and arrangement of the parts within the principles of the present disclosure up to, and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.