| 摘要 |
An LED unit includes an LED and an envelope receiving the LED therein. The envelope includes a bottom substrate fixing the LED thereon, a sidewall angling upwardly from the substrate and surrounding the LED, and a lens formed in the sidewall and located above the LED. The lens has two aspheric surfaces with different curvatures to collect light deflected at a small angle relative to an axis of the LED into a parallel pattern. The sidewall has upper and lower conical inner circumferences and a parabolic outer circumference to direct light deflected at a large angle relative to the axis of the LED into parallel pattern. The lower inner circumference of the sidewall has an angle of 2&pgr;/5 to 13&pgr;/30, and the upper inner circumference of the sidewall has an angle of 5&pgr;/36 to 7&pgr;/36.
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