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Wide Color Gamut LCD using spectral-sequential hybrid backlight system

IP.com Disclosure Number: IPCOM000127744D
Publication Date: 2005-Sep-13

Publishing Venue

The IP.com Prior Art Database

Abstract

ID689405

This text was extracted from a Microsoft PowerPoint presentation.
This is the abbreviated version, containing approximately 44% of the total text.

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Wide Color Gamut LCD using spectral-sequential hybrid backlight system


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Abstract

A wide Color Gamut LCD is proposed using a spectral-sequential; hybrid backlight system.

The backlight system is using a “standard” fluorescent tube backlight system, where the tubes are flashed. While the fluorescent tubes are on, the backlight system in combination with the LCD panel (which might be a conventional LCD panel with standard color filter pattern) is able to display colors within the standard color gamut.

While the florescent tubes are off, a set of RGB LED’s in the backlight systems are switched on. While the LED’s are on, the backlight system in combination with the LCD panel is able to display out of EBU colors.

Since natural colors outside the EBU have only a very limited brightness, the amount of light that need to be generated by the LED’s is very limited, such that (1) the cost increase of the backlight-system is relatively low, and (2) the efficiency of the backlight-system remains relatively high.


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Wide color gamut LCD

      Low Power Red LED’s, always on Low Power Green LED’s, always on Low Power Blue LED’s, always on

Standard
Fluorescent
Tubes
Pulsed operated

LCD display module Containing
LCD panel having
standard color filter pattern
Active display area
             


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Background

Most display companies are developing wider colour gamut display products, and the first products using LED backlight systems have been introduced to the market.

At the moment, most companies have chosen for a full LED backlight solution, however such solution has a number of disadvantages to overcome, such as high cost, high power consumption, uniformity problems, temperature problems in the display, requirement of an adopted colour filter pattern in the LCD.


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Proposal

A Wide Colour Gamut LCD display having the following advantages:

  Standard colour filter pattern can be used

  Relatively low cost uplift

  Nearly same power consumption than conventional CCFL backlight LCD’s

  No fans required for cooling


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Essential feature(s)

A Wide Colour Gamut LCD display having the following features:

  Wide colour Gamut

  Display cost in-between standard CCFL solution and full LED backlight solution

  System efficiency close (but somewhat higher) than CCFL backlight systems

  Power consumption close to conventional CCFL backlight LCD’s

  Cooling problems equal to conventional CCFL backlight LCD’s


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Detailed description

Figure 1 shows a conventional LCD system having a conventional fluorescent backlight system.

Figure 2 shows the colour gamut as obtained with the LCD system of figure 1. Normally such display systems has 3 primary colours Rs, Gs, Bs having colour coordinates that are located nearby the EBU colour coordinates, but within the EBU colour space.

Figure 3 shows the new proposed backlight system. RGB LED’s are positioned below each CCFL tube (figure 4).

While the CCFL tubes are on, the dis...