Patent Publication Number: US-2013240928-A1

Title: Optical lens and light emitting diode package using the same

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an optical lens, and particularly to a light emitting diode (LED) package using the same whereby the LED package can have increased light output in lateral direction. 
     2. Description of Related Art 
     LEDs have been widely promoted as light sources of electronic devices owing to many advantages, such as high luminosity, low operational voltage and low power consumption. However, a viewing angle of light generated by the LED is 90° to 120° (±45° to ±60°) which causes the light to be too intensive at the forward direction and too weak at the lateral direction, whereby the LED is not suitable for use in illumination. 
     Therefore, an optical lens and an LED package using the optical lens which are capable of overcoming the above described shortcomings are desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       The only drawing shows a schematic, cross sectional view of an LED package having an optical lens in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an LED package  1  in accordance with an embodiment of the present disclosure includes an LED light source  10  and an optical lens  20  located on the light path of the LED light source  10 . 
     In this embodiment, the LED light source  10  includes a substrate  11  with an electrode structure  12 , an LED chip  13  mounted on and electrically connected to the electrode structure  12 , a reflection cup  14  surrounding the LED chip  13 , and an encapsulation layer  15  received in the reflection cup  14  and sealing the LED chip  13  therein. The electrode structure  12  consists of an anode and a cathode. The LED chip  13  is mounted to the electrode structure  12  by flip chip. The encapsulation layer  15  includes a resin and fluorescent particles dispersed in the resin whereby light generated by the LED chip  13  can be converted to another light having a desired color, for example, white. 
     The optical lens  20  is located over the LED light source  10  and receives the LED light source  10  therein. The optical lens  20  is used for changing the light path of the light from the LED light source  10 . The optical lens  20  is made of transparent material with superior optical performance, such as glass, PMMA (polymethylmethacrylate) or PC (polycarbonate). In this embodiment, the optical lens  20  is symmetrically configured around a central axis OO′ thereof, which is coincided with a central axis of the LED light source  10 . To describe conveniently, a radial direction of the optical lens  20  is defined as a direction perpendicular to the central axis OO′ and away from the central axis OO′. “Radial direction” and “lateral direction” are synonymous in the disclosure. 
     The optical lens  20  includes a top surface  21 , a bottom surface  22  below the top surface  21  and a lateral surface  23  interconnecting the top surface  21  and the bottom surface  22 . The lateral surface  23  is located below the top surface  21  and above the bottom surface  22 . 
     A middle of the top surface  21  is recessed downward to a point A. The central axis OO′ of the optical lens  20  extends through the point A. A peripheral portion around the point A of the top surface  21  is convex along an upward direction. The top surface  21  includes a reflection surface  211  containing the point A and a refraction surface  212  surrounding the reflection surface  211 . Light emitted from the LED light source  10  is refracted when passing through the refraction surface  212  and reflected when impinging the reflection surface  211 . In this embodiment, the point A is configured on the central axis OO′ of the optical lens  20 , and the reflection surface  211  and the refraction surface  212  cooperatively form a smooth, convex and annular surface  213  around the point A. The reflection surface  211  is coated with reflective material such as silver. Preferably, a length of a projection of the reflection surface  211  on the horizontal plane and along the radial direction is equal to that of the refraction surface  212 . Alternatively, the lengths of the projections of the reflection surface  211  and the refraction surface  212  on the horizontal plane and along the radial direction can be adjusted according to the actual requirement. 
     The bottom surface  22  is flat, and a length of the bottom surface  22  along the radial direction is smaller than that of the top surface  21 . The middle of the bottom surface  22  is concaved upwardly and defines a receiving groove  24  for receiving the LED light source  10  therein. The receiving groove  24  defines a surface  241  away from the bottom surface  22 , and the surface  241  is concaved upwardly and defines a cavity  242  above the receiving groove  24 . In this embodiment, the receiving groove  24  and the cavity  242  are both symmetrical in regard to the central axis OO′. The cavity  242  is generally semi-ellipsoid shaped, and a length of a major axis of an ellipsoid defining the cavity  242  which is along the central axis OO′ is 1.5-2.5 times of a length of a minor axis of the ellipsoid. 
     The lateral surface  23  interconnects the top surface  21  and the bottom surface  22 , and the lateral surface  23  is a smooth curve and concaved towards to the top surface  21 . The curvature radius of the lateral surface  23  is greater than that of the annular surface  213  of the top surface  21 . The lateral surface  23  is coated with reflection material, such as silver. 
     During operation of the LED light source  10 , the light emitted from the LED light source  10  travels toward the optical lens  20  via the cavity  242 . A part of the light which strikes the reflection surface  211  of the top surface  21  is firstly reflected by the reflection surface  211  toward the lateral surface  23  of the optical lens  20  and then is reflected by the lateral surface  23  toward the refraction surface  212  of the top surface  21 . The light is finally refracted by the refraction surface  212  to travel out of the optical lens  20 . The other part of the light which directly strikes the refraction surface  212  of the top surface  21  is refracted by the refraction surface  212  to travel out of the optical lens  20 . Therefore, the optical lens  20  guides the light emitted from the LED light source  10  to lateral sides thereof, and therefore the light intensity of the light from the LED package  1  at the lateral direction is increased. 
     A particular embodiment is shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiment illustrates the scope of the disclosure but does not restrict the scope of the disclosure.