OPTICAL LENS AND LIGHT EMITTING DEVICE USING THE SAME
A light emitting device includes a light-emitting semiconductor unit and an optical lens coupled to the light-emitting semiconductor unit. The optical lens includes a top surface, a base portion opposite to the top surface, and a peripheral side surface defining a first refractive portion. The top surface is generally funnel-shaped. The first refractive portion is corrugated with a plurality of protruding ridge structures, each including a refractive surface.
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The present application is a divisional application of U.S. patent application Ser. No. 11/697,304, filed on Apr. 6, 2007, which claims foreign priority based on Chinese Patent Application No. 200610200892.2, filed in China on Sep. 22, 2006.
BACKGROUND OF THE INVENTION1. Field of the Invention
The disclosure generally relates to optical lenses for light emitting devices and, particularly, to an optical lens typically used for a side emitting light-emitting diode (LED).
2. Discussion of the Related Art
LEDs are widely applied in electronic display devices and illuminating devices, offering advantages of high illumination efficiency and a long lifetime. An LED generally includes a semiconductor chip emitting light. LEDs can be classified, according to the location of the semiconductor chip therein, as bottom emitting LEDs and side emitting LEDs.
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The optical lens 31 may be employed in side light-emitting devices, so that the side light-emitting devices may be advantageously used with light guides and reflectors that have very thin profiles and/or large illuminated areas. However, each of the first refracting surface 36 and the second refracting surface 38 is a single smooth peripheral surface. Thus it is difficult to manufacture the optical lens 31 to achieve desired light distribution characteristics and optimum light emitting angles. In addition, if the light incidence angle at the central flat portion of the bottom surface of the base portion 32 is not within a predetermined range, the light may escape from the optical lens 31 through the reflecting surface 34 rather than reflecting to the first refracting surface 36. When this happens, the efficiency of light utilization is reduced.
Therefore an optical lens which can overcome the above-described shortcomings is desired, as is a light emitting device employing the optical lens.
The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present optical lens and light emitting device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and all the views are schematic.
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The light-emitting semiconductor unit 200 includes a package body 201, and a semiconductor chip 202 fixed on the package body 201. The package body 201 includes a protruding portion 2011 at a top end thereof, and a connecting portion 2012 at an opposite bottom end thereof. The semiconductor chip 202 is disposed on a middle of the protruding portion 2011. The connecting portion 2012 is configured for electrically connecting the semiconductor chip 202 to an external circuit (not shown). The semiconductor chip 202 has a light emitting PN (positive negative) junction, and is configured for emitting light. The semiconductor chip 202 may be of any of various shapes, including a cube, a rectangular block, a hemisphere, or other.
The optical lens 300 is symmetrical about the central axis 101. For example, the optical lens 300 can be cylindrically symmetrical about the central axis 101. The optical lens 300 includes a top surface 301, a base portion 304 opposite to the top surface 301, and a peripheral side surface (not labeled). The peripheral side surface has a corrugated refractive portion 302 and a smooth refractive portion 303 thereat. The base portion 304 has an inverted U-shaped cross-section taken along a plane passing through the central axis 101, and defines a cavity (not labeled) receiving the protruding portion 2011 therein. Thus, the semiconductor chip 202 disposed on the middle of the protruding portion 2011 is protected. In alternative embodiments, the optical lens 300 may be radially symmetrical about the central axis 101. That is, the optical lens 300 may be generally polyhedral, with the peripheral side surface thereof being generally polygonal.
The optical lens 300 is made of transparent material, such as (but not limited to) cyclic olefin copolymer (COC), polymethyl methacrylate (PMMA), polycarbonate (PC), PC/PMMA, silicone, fluorocarbon polymer, or polyetherimide (PEI). The optical lens 300 may be manufactured independently using any of various well-known techniques, such as diamond turning (i.e., the optical lens 300 is shaped by a lathe with a diamond bit), injection molding, or casting. Alternatively, the optical lens 300 may be integrally formed on the package body 201 having the semiconductor chip 202 by any of various techniques such as (but not limited to) injection molding (e.g., insert molding), or casting.
The top surface 301 is substantially funnel-shaped or cone-shaped. If the optical lens 300 is cylindrically symmetrical about the central axis 101, the top surface 301 has the same symmetrical double-curved cross-section taken along any plane passing through the central axis 101. The two curves of the symmetrical double-arc shape are convex, with the top surface 301 being generally convex. That is, the top surface 301 has a uniform curvature through 360° measured around the central axis 101. Thereby, the top surface 301 provides a total internal reflective surface. This means the top surface 301 can effectively reflect light so that the light exits the optical lens 300 through the corrugated refractive portion 302. If the optical lens 300 is radially symmetrical about the central axis 101, the top surface 301 may have a symmetrical double-curved cross-section for a cross-section taken along a plane passing through the central axis 101, and may have two or more different double-curved cross-sections taken along a plane passing through the central axis 101, depending on where the plane of the cross-section passes through the central axis 101 is located, and depending on the particular radially symmetrical configuration of the optical lens 300. That is, the top surface 301 includes a plurality of curved portions connected to each other. The curved portions cooperatively provide the top surface 301 with a total internal reflective surface. Thereby, the top surface 301 can effectively reflect light so that the light exits the optical lens 300 through the corrugated refractive portion 302.
The corrugated refractive portion 302 includes a top end (not labeled) connecting to the top surface 301, and a bottom end (not labeled) connecting to the smooth refractive portion 303. The bottom end of the corrugated refractive portion 302 is configured to be lower than a bottommost extremity of the top surface 301. The corrugated refractive portion 302 includes a plurality of protruding ridge structures that encircle or surround the optical lens 300 thereat. In the illustrated embodiment, the ridge structures are parallel to each other. Each of the ridge structures has a triangular cross-section taken along a plane passing through the central axis 101. In the illustrated embodiment, the triangular cross-sections of the ridge structures have the same orientation. Each of the ridge structures includes an angled refractive surface 3021. In the illustrated embodiment, the angled refractive surfaces 3021 of the ridge structures are angled at the same angle relative to the central axis 101. A desired light emitting angle of each ridge structure can be obtained by configuring the angle of the refractive surface 3021 accordingly. It should be understood that in alternative embodiments, the refractive surfaces 3021 may have different angles. Thus, the light distribution characteristics of the corrugated refractive portion 302 can be configured as needed.
In one embodiment, the smooth refractive portion 303 has a cylindrical surface. The smooth refractive portion 303 is configured for refracting light that is directly received from the semiconductor chip 202, that is, light that is not reflected by the top surface 301. The light refracted at the smooth refractive portion 303 then exits the optical lens 300.
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It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
Claims
1. A light emitting device, comprising:
- a light-emitting semiconductor unit; and
- an optical lens coupled to the light-emitting semiconductor unit, the optical lens comprising:
- a top surface;
- a base portion opposite to the top surface; and
- a peripheral side surface defining a first refractive portion corrugated with a plurality of protruding ridge structures, each including a first refractive surface.
2. The light emitting device as claimed in claim 1, wherein the light-emitting semiconductor unit includes a package body disposed adjacent to a bottom of the optical lens and a semiconductor chip fixed on the package body.
3. The light emitting device as claimed in claim 2, wherein the package body includes a protruding portion at an end thereof on which the semiconductor chip is disposed, and the base portion defines a bottom cavity receiving the protruding portion bearing the semiconductor chip thereon.
4. The light emitting device as claimed in claim 1, wherein the peripheral side surface further defines a second refractive portion including a top end adjacent to the top surface and a bottom end adjacent to the second refractive portion.
5. The light emitting device as claimed in claim 4, wherein the second refractive portion is corrugated with a plurality of protruding ridge structures, each including a second refractive surface, symmetrically relative to each of which each of the first refractive surfaces of the first refractive portion is oriented.
6. The light emitting device as claimed in claim 4, wherein the second refractive portion is cylindrical.
7. The light emitting device as claimed in claim 6, wherein the first refractive portion includes a first refractive section and a second refractive section, each including a plurality of ridge structures, each of which has a triangular cross-section, the ridge structures of the first refractive section including a plurality of first refractive surfaces having the same first angle relative to a central axis of the optical lens, the ridge structures of the second refractive section including a plurality of second refractive surfaces having the same second angle relative to the central axis, and the first angle of the first refractive surfaces is different from the second angle of the second refractive surfaces.
8. The light emitting device as claimed in claim 1, wherein the optical lens is made of a transparent material selected from the group consisting of cyclic olefin copolymer, polymethyl methacrylate, polycarbonate, silicone, fluorocarbon polymer, and polyetherimide.
9. The light emitting device as claimed in claim 1, wherein each of the ridge structures has a triangular cross-section, wherein the triangular cross-sections of the ridge structures have the same orientation, and each of the ridge structures includes an angled refractive surface, and the angled refractive surfaces of the ridge structures are angled at the same angle relative to a central axis of the optical lens.
10. The light emitting device as claimed in claim 1, wherein the optical lens further comprises a reflecting sheet above the top surface.
11. The light emitting device as claimed in claim 1, wherein the optical lens further comprises a reflecting film on the top surface.
Type: Application
Filed: Nov 18, 2009
Publication Date: Mar 18, 2010
Applicant: HON HAI PRECISION INDUSTRY CO., LTD. (Tu-Cheng)
Inventor: SHAO-HAN CHANG (Tu-Cheng)
Application Number: 12/620,606
International Classification: H01L 33/00 (20100101);