Dual Modulation Display Light Conversion Layer

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Solution Overview

Problem

Conventional display systems using color filters in LCDs and OLEDs waste significant light, converting it into heat and degrading performance and lifetime, making it costly to achieve wide color gamut and high luminance.

Innovation Solution

A dual modulation display system with a light conversion layer, using quantum dots or phosphor materials, where illumination sources emit light that is converted and modulated based on light field simulations to address color shifts, binning differences, and temperature variations, reducing yellow light spectral components and optimizing light transmission through subpixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If color filters are used in LCD and OLED displays to produce red, green, and blue light spectra, then color gamut is achieved, but significant light is wasted and converted into harmful heat which degrades performance and lifetime

Engineering Contradiction:

Improvecolor gamutVSAvoidlight wastage

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent extracts the color filtering function from the traditional color filter layer and replaces it with a light conversion layer containing quantum dots or phosphor materials. This extraction eliminates the need to block unwanted wavelengths, as the light conversion layer directly converts blue or ultraviolet light into the desired red and green wavelengths through photoluminescence, thereby reducing light wastage while maintaining color gamut

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental parameter of light generation from subtractive color filtering to additive light conversion. By using quantum dots or phosphor materials with specific emission spectra, the system converts incoming blue or ultraviolet light into precise red and green wavelengths, optimizing the spectral distribution and reducing energy loss as heat

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If color filters block green and blue light spectra to produce red light, then red color output is achieved, but the blocked light is wasted and converted into harmful heat

Engineering Contradiction:

Improvered light outputVSAvoidheat degradation

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of blocked light into beneficial photoluminescence emission. Instead of blocking blue light to produce red, the light conversion layer absorbs blue light and re-emits it as red light through quantum dot or phosphor materials, transforming what would be wasted energy into useful visible light output

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent substitutes the mechanical/optical system of color filtering (using absorptive filters) with a photoluminescent conversion system. This replacement eliminates the harmful heat generation associated with light absorption and re-emission through filtering, as the light conversion process occurs through quantum mechanical transitions in quantum dots or phosphor materials

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If individually controllable illumination sources and light conversion layers are used to reduce light wastage, then luminance efficiency is improved, but device complexity increases

Engineering Contradiction:

Improveluminance efficiencyVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the illumination source control and light conversion functions into an integrated backlight unit. The individually controllable illumination sources (LEDs) are combined with the light conversion layer in a unified structure, allowing simultaneous control of multiple color channels while maintaining a compact form factor and reducing overall system complexity

Inventive Principle:

Principle #5Merging (Combining)

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 enhances display performance by minimizing light wastage, reducing color shifts, and improving luminance, thereby extending the display's lifespan and reducing manufacturing costs.

Implementation Method 1

The light conversion layer converts the first light into second light

Methodology Applied

Scientific EffectLight conversion: Photoluminescence

Data Source

PatentUS11074875B2Techniques for dual modulation display with light conversion

Publication Date: 2021.07.27 DOLBY LABORATORIES LICENSING CORP

AI summary

Techniques for driving a dual modulation display include generating backlight drive signals to drive individually-controllable illumination sources. The illumination sources emit first light onto a light conversion layer. The light conversion layer converts the first light into second light. The light conversion layer can include quantum dots or phosphor materials. Modulation drive signals are generated to determine transmission of the second light through individual subpixels of the display. These modulation drive signals can be adjusted based on one or more light field simulations. The light field simulations can include: (i) a color shift for a pixel based on a point spread function of the illumination sources; (ii) binning difference of individual illumination sources; (iii) temperature dependence of display components on performance; or (iv) combinations thereof.