Abstract:
Disclosed herein is a Light Emitting Diode (LED) light source lens for emitting light in a lateral direction. The LED source lens includes an upper part, an upper part and a central part. The upper part includes an upper part reflecting surface bent symmetrically with respect to the central axis of the lens, and an upper part refracting surface extended from the end of the upper part reflecting surface parallel with the central axis. The central part includes a side surface extended from the lower end of the upper part refracting surface and bend inwards, and refracts or reflects light through the side surface. The lower part accommodates the LED light source, and includes an arch-shaped lower part refracting surface extended outwards from the lower end of the side surface of the central part. The light radiated from the LED light source is emitted perpendicular to the central axis.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     U.S. Pat. No. 6,679,621 B1 is an application related to the present invention, and is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, generally, to a light emitting device light source lens having upper, central and lower parts, and, more particularly, to a light emitting device light source lens having upper, central and lower parts that includes a structure for causing total internal reflections and refraction in light paths extending from the lower part to the upper part, thereby efficiently transmitting light through a side surface. 
     2. Description of the Related Art 
     Display and illumination optical systems require light sources that are environment-friendly and have high efficiency and long life spans. Furthermore, with the increase of the efficiency and luminance of Light Emitting Diodes (LEDs), alternative light sources using LEDs have been developed. In particular, as projects such as the development of environment-friendly televisions have been announced, the research and development of Liquid Crystal Devices (LCDs) using LED light sources have been further promoted. In order to meet such technical demand, the need for efficiently shaped LED light source lenses for display and illumination light sources is further increasing. 
     U.S. Pat. No. 6,679,621 B1 discloses a side emitting LED and the lens thereof. In detail, the patent discloses a lens structure that includes a reflecting surface and refracting surfaces and, thereby, allows light to be emitted from the LED through the side surface of the lens. The lens will be described with reference to  FIG. 1  below. 
     Referring to  FIG. 1 , a prior art side emitting lens  100  includes an upper part  10  and a lower part  30 . The upper part includes a reflecting surface  12  bent symmetrically about the central axis  40  of the lens, and a first refracting surface  14  extended from the end of the reflecting surface at an angle of inclination with respect to the central axis  40 . The lower part includes a second refracting surface  32  arcuately extended from the lower end of the first refracting surface  14  to a bottom surface  34 . 
     The light paths based on the prior art side emitting lens  100  are described in the following. Light emitted from an LED light source located at the focal point  50  of the lens  100  can enter the lens through the bottom surface  34  of the lens. Light directly incident on the reflecting surface  12  of the upper part  10  is radiated from the focal point  50 , is reflected from the reflecting surface  12  of the upper part  10  to the first refracting surface  14 , is refracted at the first refracting surface  14 , and is emitted perpendicular to the central axis  40  of the lens (refer to the arrow L 1 ). 
     Furthermore, light directly incident on the second refracting surface  34  is radiated from the LED light source located at the focal point  50 , is refracted by the second refracting surface  34 , and is emitted perpendicular to the central axis  40  of the lens (refer to the arrow L 2 ). 
     As described above, the prior art side emitting lens is characterized in that most of the light is emitted through the first and second refracting surfaces of the lens, so that light radiated from the LED light source is emitted through the side surfaces of the lens. 
     However, the prior art side emitting lens is problematic in that the end of the reflecting surface of the upper part is sharp, so that light radiated from the LED light source is radiated onto a screen through the sharp portion of the reflecting surface, and it is difficult for light incident on the reflecting surface of the upper part (in particular, a portion of the reflecting surface adjacent to the end thereof) to propagate along a correct light path. 
     Furthermore, since the end of the reflecting surface of the upper part is sharp, there is concern about deformation due to breakage or damage at the time of mass production. When the lens is deformed, the deformed portion of the lens is located adjacent to a screen, so that the screen may be damaged by the deformed portion. 
     Meanwhile, the second refracting surface of the lower part functions to minimize the amount of light propagating to the upper part and emit light to the side surface. Since the second refracting surface has a wider area than does the first refracting surface, variation in the curvature of a surface must be high in order to emit light from the second refracting surface at a desired angle, thereby causing the problem of increasing the amount of light confined inside the lens. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an LED light source lens, in which a refracting surface is formed to extend from the end of an upper part reflecting surface parallel with the central axis of the lens, thereby facilitating the manufacture of the lens, and in which an inclined surface is formed by bending the side surface of a central part connected to an upper part, so that light paths are changed, thereby emitting light through the side surface of the lens. 
     Another object of the present invention is to provide an LED light source lens, in which the maximum diameter of a lower part refracting surface is smaller than that of the upper part reflecting surface, thereby reducing the loss of light due to total internal reflections generated in a lower part. 
     In order to accomplish the above object, the present invention provides an LED light source lens for emitting light in a lateral direction, including an upper part including an upper part reflecting surface bent symmetrically with respect to the central axis of the lens, and an upper part refracting surface extended from the end of the upper part reflecting surface parallel with the central axis; a central part including a side surface extended from the lower end of the upper part refracting surface and bend inwards, and refracting or reflecting light through the side surface; and a lower part accommodating the LED light source, and including an arch-shaped lower part refracting surface extended outwards from the lower end of the side surface of the central part; wherein the light radiated from the LED light source is emitted perpendicular to the central axis. 
     Preferably, the lower part, the central part and the upper part are integrally injected. 
     Preferably, the bent side surface of the central part includes an inclined surface at least partially inclined inwards, and light is refracted or reflected through the inclined surface. 
     Preferably, the inclined surface has an upper end bent and extended to the lower end of the upper part refracting surface, and a lower end bent and extended to the lower part refracting surface. 
     Preferably, the lower part refracting surface has a maximum diameter that is smaller than the maximum diameter of the upper part reflecting surface. 
     Preferably, the inclined surface has an upper end bent and extended to the lower end of the upper part refracting surface, and a lower end extended directly to the lower part refracting surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a sectional view showing an example of a prior art lens; 
         FIG. 2  is a sectional view showing an LED light source lens according to a first embodiment of the present invention; 
         FIG. 3  is a diagram showing light paths through the LED light source lens of  FIG. 2 ; 
         FIG. 4  is a sectional view showing an LED light source lens according to a second embodiment of the present invention; 
         FIG. 5  is a diagram showing light paths through the LED light source lens of  FIG. 4 ; 
         FIG. 6  is a sectional view showing an LED light source lens according to a third embodiment of the present invention; and 
         FIG. 7  is a diagram showing light paths through the LED light source lens of  FIG. 6 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. 
     With reference to the accompanying drawings, preferred embodiments of the present invention are described below. 
       FIG. 2  is a sectional view showing an LED light source lens  200  according to a first embodiment of the present invention, and  FIG. 3  is a diagram showing light paths through the LED light source lens  200  of  FIG. 2 . 
     The LED light source lens  200  according to the first embodiment of the present invention includes an upper part  110 , a central part  120  and a lower part  130 . The LED light source lens  200  is characterized in that the maximum diameter D 1  of a lower part refracting surface  132  is designed to be smaller than the maximum diameter D 2  of an upper part reflecting surface  112 . 
     The upper part  110  includes the upper part reflecting surface  112  and the upper part refracting surface  114 . The upper part reflecting surface  112  has a shape that is bent symmetrically with respect to a central axis  140 , while the upper part refracting surface  114  is formed to extend from the end of the upper part reflecting surface  112  and to be parallel with the central axis  140  to a certain distance. 
     The central part  120  includes a side surface  122  extended from the lower end of the upper part refracting surface  114 , and the side surface  122  includes an inclined surface  124  inclined radially inwards at a certain angle. Furthermore, the upper end of the inclined surface  124  is bent perpendicular to the central axis  140  and extends to the lower end of the upper part refracting surface  114 , the lower end of the inclined surface  124  is bent perpendicular to the central axis  140  and extends to the lower part refracting surface  132 , and light can be selectively reflected or refracted at the inclined surface  124 . The reflection or refraction of light by the inclined surface  124  will be described in the following description of light paths. 
     The lower part  130  includes an arch-shaped lower part refracting surface  132  extending radially outwards from the lower end of the side surface  122  of the central part  120 . An LED light source  150  for radiating light to the lens is accommodated in the lower portion of the lower part  130 . 
     In general, reflection, which occurs at boundary surfaces (for example, the upper part reflecting surface and the inclined surface) formed by the material of the lens and air, includes total internal reflection, which occurs when the incident angle of light is larger than a critical angle. Furthermore, refraction occurs at other boundary surfaces (for example, the upper part refracting surface, the lower part refracting surface and the inclined surface) when the incident angle of light is smaller than the critical angle. 
     With respect to light paths according to the first embodiment of the present invention, light paths L 1  and L 2  are similar to those described in the document in which the prior art technology is described. In detail, light directly incident on the upper part reflecting surface  112  is radiated from the LED light source  150 , is reflected by the upper part reflecting surface  112  to the upper part refracting surface  114 , is refracted by the upper part refracting surface  114 , and is emitted perpendicular to the central axis  140  of the lens (refer to the arrow L 1 ). Alternatively, light is radiated from the LED light source  150 , is directly incident on the lower part refracting surface  132 , is refracted by the lower part refraction surface  132 , and is emitted perpendicular to the central axis  140  (refer to the arrow L 2 ). 
     With respect to other light paths, the part of the light that is radiated from the LED light source is passed through the lower part refracting surface  132  and directly enters the upper part  110 , is refracted at the inclined surface  124  formed on the side surface  122  of the central part  120 , is reflected at the upper part reflecting surface  112 , and is emitted through the upper part refracting surface  114  (refer to the arrow L 3 ). The part of the light that is radiated from the LED light source, is directly incident on the upper part reflecting surface  112 , and does not reach the upper part refracting surface  114  even though it is reflected at the upper part reflecting surface  112  is refracted and emitted through an inclined surface  124  formed on the side surface  122  of the central part  120  (refer to the arrow L 4 ). 
     As described above, the LED light source lens having a bent side surface according to the first embodiment of the present invention includes the upper part, the central part and the lower part. In particular, a side surface that is bent inwards and extends from the lower end of the upper part refracting surface and, then, is inclined may be provided. Accordingly, the part of the light that is radiated from the LED light source and is directly incident on the upper part through the lower part is reflected at the side inclined surface of the central part and is emitted via the upper part reflecting surface and the upper part refracting surface, thereby reducing erroneous light paths caused by the prior art technology. 
     Furthermore, the LED light source lens is manufactured and provided such that the maximum diameter of the lower part refracting surface is smaller than the maximum diameter of the upper part reflecting surface. Accordingly, most of the light is emitted through the upper part and the inclined surface of the central part, so that the loss of light due to total internal reflections in the lower part can be reduced. 
       FIG. 4  is a sectional view showing an LED light source lens  300  according to a second embodiment of the present invention, and  FIG. 5  is a diagram showing the light paths of the LED light source lens  300  of  FIG. 4 . 
     The LED light source lens  300  according to the second embodiment of the present invention, as shown in  FIG. 2 , includes an upper part  210 , a central part  220  and a lower part  230 . The LED light source lens  300  is characterized in that the lower end of the inclined surface  224  of the side surface  222  is directly connected to the lower part refracting surface  232  without bending and the region of the lower part  230  larger than that of the lower part of the first embodiment (refer to  130  of  FIG. 2 ). 
     The upper part  210  includes an upper part reflecting surface  212  and an upper part refracting surface  214 . The shapes of the upper part reflecting surface  212  and the upper part refracting surface  214  are the same as those described in conjunction with  FIG. 2 . 
     The central part  220  includes the side surface  222 , and the side surface  222  includes an inclined surface  224  which is radially inwardly inclined at a certain angle. Furthermore, the upper end of the inclined surface  224  extends to the lower end of the upper part refracting surface  214  after being bent two times perpendicularly with respect to the central axis  240 . The lower end of the inclined surface  224  is directly connected to the lower part refracting surface  232 , which is radially outwardly curved from the central axis  240 . Light can be reflected or refracted at the inclined surface  224 . 
     The lower part  230  includes the arch-shaped lower part refracting surface  232  extending outwards from the lower end of the side surface  222  of the central part  220 . An LED light source  250  for radiating light to the lens is accommodated in the lower part  230 . 
     Of light paths according to the second embodiment of the present invention, light paths L 1  and L 2  are the same as those described in conjunction with the first embodiment. Light paths L 3  and L 4  are the same as those described in conjunction with  FIG. 3 . 
     As described above, the lens according to the second embodiment of the present invention is formed such that the lower end of the inclined surface  224  of the side surface  222  directly extends to the lower part refracting surface  232  and the lower part  230  is larger than the lower part of the first embodiment (refer to  130  of  FIG. 2 ). As a result, the part of the light that is emitted through the upper part reflecting surface and the upper part refracting surface does not reach the upper part reflecting surface or the upper part refracting surface, but is directly refracted at and emitted from the lower part refracting surface. 
       FIG. 6  is a sectional view showing an LED light source lens  400  according to a third embodiment of the present invention, and  FIG. 7  is a diagram showing the light paths of the LED light source lens  400  of  FIG. 6 . 
     The LED light source lens  400  according to the third embodiment of the present invention includes an upper part  310 , a central part  320  and a lower part  330 . Compared with the second embodiment, the third embodiment is configured such that the lower part inclined surface  324  of the central part  320  is bent and then connected to the lower part refracting surface  332 . Compared with the first embodiment, the third embodiment is characterized in that the upper end of the inclined surface  324  is bent two times and then connected to the lower end of the upper part refracting surface. 
     The upper part  310  includes an upper part reflecting surface  312  and an upper part refracting surface  314 . The shapes of the upper part reflecting surface  312  and the upper part refracting surface  314  are the same as those described in conjunction with  FIG. 2 . 
     The central part  320  includes a side surface  322  extending from the lower end of the upper part refracting surface  314 , and the side surface  322  includes an inclined surface  324  inclined radially inwards at a certain angle. Furthermore, the upper end of the inclined surface  324  extends to the lower end of the upper part refracting surface  314  perpendicularly with respect to the central axis  340  after being bent two times, and the lower end of the inclined surface  324  extends to the lower part refracting surface  332  perpendicularly with respect to the central axis  340 . Light is selectively reflected and refracted at the inclined surface  324 . 
     The lower part  330  includes an arch-shaped lower part refracting surface  332  outwardly extending from the lower end of the side surface  322  of the central part  320 . An LED light source  350  for radiating light to the lens is accommodated in the lower part  330 . 
     Light paths L 1  and L 2  according to the third embodiment of the present invention are similar to those described in the document in which the prior art technology is described. Light paths L 3  and L 4  are also similar to those described in conjunction with  FIG. 3 . 
     As described above, the LED light source lens having the bent side surface according to the present invention includes the upper part, the central part and the lower part. In particular, the lower end of the upper part refracting surface includes the side surface having the inclined surface that is inwardly bent and extended. Accordingly, part of light, which is radiated from the LED light source, passes through the lower part and directly enters the upper part, is reflected at the inclined surface of the central part and emitted through the upper part reflecting surface and the upper part refracting surface, thereby reducing erroneous light paths caused by the prior art technology. 
     Furthermore, the LED light source lens is configured and provided such that the maximum diameter of the lower part refracting surface is smaller than the maximum diameter of the upper part reflecting surface. As a result, most of light is emitted from the upper part and the inclined surface of the central part, so that the loss of light due to total internal reflections in the lower part can be reduced. 
     As described above, the present invention is characterized in that an LED light source lens, in which the upper part refracting surface is formed, the side surface is bent and at least a portion of the side surface forms the inwardly inclined surface, is provided and in that the light of the LED light source is efficiently emitted through the side surface of the lens without passing through erroneous paths. 
     As described above, although the LED light source lens of the present invention having the bent side surface has been described in conjunction with the preferred embodiments of the present invention, it is apparent to those skilled in the art that various corrections, variations and modifications of the present invention can be made without departing from the spirit of the present invention. 
     According to the LED light source lens of the present invention having upper, central and lower parts, the refracting surface extends from the end of the upper part reflecting surface parallel with the central axis, the side surface of the central part is bent and at least a portion of the side surface forms an inclined surface, so that light can be efficiently emitted through the side surface by changing erroneous light paths using the inclined surface, and the mass production of the LED light source lens is enabled. 
     Furthermore, the LED light source lens of the present invention can be manufactured such that the maximum diameter of the lower part refracting surface is smaller than the maximum diameter of the upper part reflecting surface, so that the loss of light due to total internal reflections in the lower part can be reduced.