Browse Prior Art Database

Frontlighting system with LED's

IP.com Disclosure Number: IPCOM000010449D
Publication Date: 2002-Dec-03
Document File: 1 page(s) / 37K

Publishing Venue

The IP.com Prior Art Database

Abstract

ID608408

This text was extracted from a Microsoft Word document.
This is the abbreviated version, containing approximately 64% of the total text.

Frontlighting system with LED's

A tapered light guide for mixing light from different LED's in a back light display system is known. The advantages of such a system are the compact size and the high color mixing efficiency.

Such a light guide can also be used for front light display systems, where the viewer has to look through the light guide in order to see the display. The advantage of using these types of light guides in front light display systems is that they are totally transparent, so the display can be seen clearly and is not distorted by light extracting features in the light guide.

A disadvantage is that the light guide extracts light on both sides, which means that only 50% of the light is used to illuminate the front light display. The other 50% is directed towards the viewer, decreasing the contrast.

The proposed solution is to use a second tapered light guide to capture this stray light. The captured light can either be masked, or recycled to increase the efficiency of the system

In the pictures, this process is explained:

In picture 1, a light source (1) illuminates a tapered light guide (2). A reflection structure on the back (3) reflects the light and gives it the right distribution. The light is extracted from the taper to the top (4) and the bottom (5).

In picture 2, a front light display (6) is shown, which reflects the light (5) towards the viewer (7). This display can be a reflective LCD, for instance. Note that the original top light (4) is also direc...