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BACKLIGHT WITH VARIABLE LUMINANCE PROFILE

IP.com Disclosure Number: IPCOM000020108D
Publication Date: 2003-Oct-27
Document File: 1 page(s) / 92K

Publishing Venue

The IP.com Prior Art Database

Abstract

ID614859

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Background

Computer monitor and television have a different set of requirements as a display. Typically, TV requires higher brightness and lower CCT of white color than the monitor. Besides, the luminance profile of the TV is typically non-uniform. Luminance is highest in the center and smoothly decays towards the corners to >50% of the luminance in the centers. By contrast, the monitor typically has a very uniform brightness; reduction is not more than 80% of the luminance in the center.

Modern multimedia monitors are designed having both applications in mind: these are both computer monitors for office applications like spreadsheets and word processing and screens for video playback (DVD and clips). Backlight brightness profile for these displays is a compromise. Present invention addresses this issue.

Solution

The proposed solution is to have a backlight with a luminance profile that can be switched electronically between the flat and the parabolic state. Such a system can be realized using a direct backlight with the light sources distributed in a 2-dimensional array. Depending on the user application (monitor for office work or video viewing) the brightness profile can be changed by modifying the intensity or the ray pattern of the light sources.

For, example, in an LED backlight the LEDs can be combined in the central group and a peripheral group. For the monitor application the driving current through the LEDs of both groups adjusted as to have a flat luminance profil...