Patent Application
20120140483
1. Technical Field
The present disclosure relates to LED (light emitting diode) units, and more particularly, to an LED unit having a lens.
2. Description of Related Art
Light emitting diodes (“LEDs”) are widely used as new types of light sources in various applications such as road lamps, traffic lamps, tunnel lamps, resident lamps and so on. A lens is often used with an LED for collimating the light beams generated from the LED in a predetermined pattern. In LED products designed to illuminate areas at a long distance, a convex lens may be used to converge the light beams emitted from the LED. However, in other applications, such as vehicle headlamps, the LED products need to be able to provide illuminations not only to the area far away from the LED, but also the area near the LED. LED products with the conventional convex lens may not meet such requirements.
What is needed, therefore, is an LED unit which may overcome the deficiencies as described above.
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.
Referring to
In one embodiment, the LED 10 generates white light. However, other types of LEDs which generate different light colors, may also be used in the LED unit 100. The lens 20 may be made of a transparent material such as epoxy, silicon, glass and so on. Referring to
The first member 22 is a Fresnel lens curving outward from the top face 250 of the base 25. Circumferences of the first member 22 have diameters gradually decreasing outward from the top face 250 to a top of the Fresnel lens. The first member 22 includes a plurality of concentric annulus 222 arranged from an outer circumferential periphery towards a center of the first member 22. The first member 22 may converge a part of incident light from the light incident face 21 into narrow light beams to illuminate areas far away from the LED unit 100. Preferably, the first member 22 has an optical axis O perpendicular to the top face 250 of the base 25. The LED 10 may be placed on the axis O and on the convex side of the lens 20 so that the light emitted by the LED 10 may be collimated by the first member 22 to parallel light beams emitted out of the LED unit 100. Outer faces of the annulus 222 of the first member 22 may function as a first light emergent face 220 for transmitting the light out of the lens 20.
The second member 26 is connected with the first member 22 and has a height less than a height of the first member 22. A sidewall of the second member 26 and a sidewall of the first member 22 cooperatively form a continuous annular lateral face 28. The continuous annular lateral face 28 is connected to the top face 250 of the base 25. The continuous annular lateral face 28 has a largest height where the second member 26 and the first member 22 join. The second member 26 has an inclined top face. The inclined top face of the second member 26 may has a rough surfaced finish which may be formed by a plurality of parallel saw-tooth portions. The inclined top face of the second member 26 may function as a second light emergent face 23 to diffuse and direct the incident light uniformly to illuminate areas near the LED unit 100. The first member 22 is intersected by a light reflective face 24, which is connected to the second member 26. The light reflective face 24 may be flat and has a surface area less than a surface area of the second light emergent face 23, and far less than a surface area of the first light emergent face 220. The light reflective face 24 is bordered by an irregular top edge 240 and a straight bottom edge 242. The light reflective emergent face 24 is connected to the second light emergent face 23 at the straight bottom edge 242, and connected to the first light emergent face 220 at the irregular top edge 240 thereof. The light reflective 24 is at an angle a from the top face 250 of the base, wherein the angle a may be equal to or less than 90 degrees. The light reflective face 24 may also be coated with a metal layer such as a silver layer for better reflection. The light reflective face 24 may reflect light from the incident face 21 towards the first light emergent face 220. The second light emergent face 23 of the second member 26 is at an angle β from the top face 250, wherein the angle β is smaller than the angle α. An angle γ between the second light emergent face 23 and the light reflective face 24, measured facing the LED 10, is between 180 degrees and 270 degrees.
When the LED unit 100 is applied to a headlamp of a vehicle, light emitted from the first light emergent face 220 may form a high beam to illuminate areas far away from the vehicle; whereas light emitted from the second light emergent face 23 may form a low beam to illuminate an area near the vehicle. As a result, areas in front of the vehicle may have a better visibility.
It is believed that the present disclosure and its 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 present disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 099142279 | Dec 2010 | TW | national |
This patent application is related to three patent applications, having respective application Ser. Nos. 13/278,109, 13/278,112, 13/277,237, all entitled “LED UNIT”, assigned to the same assignee, and disclosures of which are incorporated herein by reference in its entirety.
