1. Technical Field
The disclosure generally relates to a lens, and more particularly, to a lens used in an LED unit which is used in a display such as a liquid crystal display (LCD).
2. Description of Related Art
Nowadays LEDs (light emitting diodes) are applied widely in displays for illuminating the screens thereof. A type of display, generally called direct-backlight display, uses a plurality of LEDs which is located behind the screen thereof to directly illuminate the screen. In order to obtain a uniform illumination for the screen, a diffusion plate is often placed between the screen and the LEDs. However, the diffusion plate must be kept a sufficient distance from the LEDs, to thereby ensure that the light emitted from the LEDs can be evenly diffused by the diffusion plate before entering the screen. Thus, a thickness of the display cannot be thin enough. A way to resolve such problem is to provide a diffusion lens for each LED. Nevertheless, the diffusion capability of the lens is still insufficient such that some hot spots may be formed on the screen even after diffusion of the light by the diffusion lens.
What is needed, therefore, is a lens used in an LED unit of a direct-backlight display which can address the limitations described.