Lens and LED unit using the same
A lens includes a bottom face, a light incident face defined in the bottom face, a plurality of light reflective faces connecting the light incident face with the bottom face, and a light emerging face opposite to the light incident face. The light incident face includes a first face and a plurality of second faces alternating with the light reflective faces. The light reflective faces are flat faces parallel to an optical axis of the lens. An LED unit using the lens is also disclosed.
1. A lens comprising:
a bottom face;
a light incident face defined in the bottom face;
a plurality of light reflective faces connecting and adjoining the light incident face adjacent to the bottom face; and
a light emerging face opposite to the bottom face;
wherein each light reflective face is totally enclosed by a top edge and a bottom edge connecting the top edge, the top edge directly connecting and adjoining the light incident face, and the bottom edge directly connecting the bottom face.
2. The lens of claim 1 , wherein the lens comprises an optical axis extending through a center of the light incident face and a center of the light emerging face, the light reflective faces being parallel to the optical axis.
3. The lens of claim 1 , wherein each light reflective face is a flat face.
4. The lens of claim 1 , wherein the light reflective faces are spaced from each other.
5. The lens of claim 1 , wherein the top edge is curved, and the bottom edge is straight.
6. The lens of claim 1 , wherein the top edge is elliptical.
7. The lens of claim 1 , wherein the light incident face comprises a first face and a plurality of second faces connecting the first face, the second faces alternating with the light reflective faces.
8. The lens of claim 7 , wherein the first face comprises an elliptical face.
9. The lens of claim 7 , wherein each second face has a width gradually increasing from the bottom face towards the first face.
10. The lens of claim 7 , wherein each second face directly connects the first face, two adjacent light reflective faces and the bottom face.
11. The lens of claim 7 , wherein a boundary between each second face and the bottom face is curved.
12. An LED (light emitting diode) unit comprising:
an LED;
a lens covering the LED, the lens comprising:
a bottom face;
a light incident face defined in the bottom face, the LED facing the light incident face;
a plurality of light reflective faces surrounding the LED, each light reflective face connecting and adjoining the light incident face with the bottom face; and
a light emerging face opposite to the bottom face;
wherein each light reflective face is totally enclosed by a top edge and a bottom edge connecting the top edge, the top edge directly connecting and adjoining the light incident face, and the bottom edge directly connecting the bottom face.
13. The LED unit of claim 12 , wherein the light reflective faces are spaced from each other without direct contact.
14. The LED unit of claim 12 , wherein the light incident face comprises a first face and a plurality of second faces connecting the first face with the bottom face, the second faces alternating with the light reflective faces.
15. The LED unit of claim 14 , wherein a boundary between each second face and the bottom face is curved.
16. The LED unit of claim 12 , wherein the top edge is curved and the bottom edge is straight.
17. The LED unit of claim 12 , wherein the LED has a height less than that of each light reflective face.