Field-Sequential LCD Using Periodic Backlight for Wide Color Gamut

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Solution Overview

Problem

Conventional liquid crystal displays (LCDs) face challenges in fully covering all natural object colors due to limitations in color gamut, requiring additional subpixels for cyan, which increases manufacturing complexity and costs, and results in lower aperture and transmittance ratios compared to conventional RGB displays.

Innovation Solution

A field sequential color LCD system with a backlight module providing red, cyan, blue, and green light in alternating sub-frame periods, using a color filter with cyan and yellow subpixels to achieve tetra-base color display without additional subpixels, and controlling backlight duration via pulse width modulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an additional subpixel is added to achieve cyan color, then color gamut coverage is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvecolor gamut coverageVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies field sequential color technology where the backlight module alternates between emitting cyan light and yellow light in different time periods (first sub-frame period and second sub-frame period). This periodic temporal separation allows the display to achieve tetra-base color coverage without adding physical subpixels, as each subpixel displays different colors at different times which the human eye perceives as simultaneous colors.

Inventive Principle:

Principle #19Periodic action

2Adaptability or versatility

If an additional subpixel is added to achieve cyan color, then color gamut coverage is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecolor gamut coverageVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The backlight module uses periodic temporal separation to emit cyan and yellow light in alternating sub-frame periods, enabling the display to achieve complete coverage of natural colors using only two color subpixels (cyan and yellow) instead of requiring an additional subpixel, thereby simplifying the color filter manufacturing process and reducing costs.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If an additional subpixel is added to achieve cyan color, then color gamut coverage is improved, but aperture ratio decreases

Engineering Contradiction:

Improvecolor gamut coverageVSAvoidaperture ratio

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

By using field sequential color technology with periodic emission of cyan and yellow backlight in alternating time periods, the patent achieves tetra-base color coverage without adding physical subpixels. This temporal multiplexing approach maintains the same physical subpixel area as conventional RGB displays, thereby preserving high aperture ratio and transmittance characteristics.

Inventive Principle:

Principle #19Periodic action

4Adaptability or versatility

If an additional subpixel is added to achieve cyan color, then color gamut coverage is improved, but transmittance ratio decreases

Engineering Contradiction:

Improvecolor gamut coverageVSAvoidtransmittance ratio

Core Design Contradiction:

Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The backlight module employs periodic temporal separation to emit cyan and yellow light in alternating sub-frame periods through the same set of subpixels. This approach achieves complete color gamut coverage without adding additional subpixels or color filter layers, thereby maintaining high light transmittance ratio and brightness characteristics comparable to conventional RGB displays.

Inventive Principle:

Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for complete coverage of natural colors with only two color subpixels, simplifying manufacturing, reducing costs, and enhancing aperture and transmittance ratios compared to tri-color RGB LCDs.

Implementation Method 1

The LCD panel includes a color filter of a first color subpixel and a color filter of a second color subpixel

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

liquid crystal displays (LCDs)

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentUS9704440B2Field-sequential color liquid crystal display and driving method thereof

Publication Date: 2017.07.11 TCL CHINA STAR OPTOELECTRONICS TECHNOLOGY CO LTD

AI summary

The present invention provides a field sequential color LCD, which includes a LCD panel and a backlight module. The LCD panel includes a color filter of a first color subpixel and a color filter of a second color subpixel, a field sequential cycle of the LCD panel includes a first sub-frame period and a second sub-frame period. The backlight module provides backlight, including red, cyan, blue and green backlights, to the LCD panel. The backlight module provides two of the four backlights in the first sub-fame period, and provides another two of the four backlights in the second sub-frame period. The above LCD can cover the pointer's gamut entirely in the natural world, only color filters of subpixels of two colors are required to achieve tetra-color (RGBC) display, no additional subpixel is required, the manufacturing process of color filter of LCD panel is simplified, and the cost is reduced.