Multibeam Diffraction Grating Backlight for 3D Displays

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Solution Overview

Problem

Passive electronic displays, such as LCDs, lack the ability to emit light, limiting their applicability and requiring external light sources, which can be inefficient.

Innovation Solution

A multibeam diffraction grating-based color backlight system that uses laterally displaced light sources of different colors and a plate light guide with a multibeam diffraction grating to direct light beams in specific angular directions, enabling the creation of a 'glasses-free' 3D electronic display by modulating light beams as pixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If passive displays are coupled to external light sources to enable light emission, then the displays can function as active displays, but the system complexity and energy consumption increase

Engineering Contradiction:
Improvelight emission capabilityVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the light source, light guide plate, and diffraction grating into an integrated backlight assembly. The multiple light sources (red, green, blue LEDs) are combined within a single light guide plate structure, eliminating the need for separate lighting systems for each color and reducing overall system complexity while maintaining full-color emission capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The light guide plate serves multiple functions simultaneously: it guides light from the sources, distributes light across the display area, and works with the diffraction grating to enable angular separation for 3D effects. This multi-functionality reduces the need for additional components and simplifies the overall system architecture.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple light sources of different colors are used to create color display, then the color gamut is improved, but the device complexity increases

Engineering Contradiction:
Improvecolor display capabilityVSAvoidnumber of light sources
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines red, green, and blue light sources within a single light guide plate structure. The light guide plate integrates all three color channels and distributes them across the display area, eliminating the need for separate lighting systems for each color and reducing overall system complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The backlight is segmented into multiple independent light sources (red LED, green LED, blue LED) that can be individually controlled. This segmentation allows for precise color management and enables the display to produce a wide color gamut while maintaining flexibility in controlling each color channel separately.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If a multibeam diffraction grating is used to direct light beams in specific angular directions, then 3D display capability is enabled, but the manufacturing precision requirements increase

Engineering Contradiction:
Improve3D display capabilityVSAvoidgrating precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The diffraction grating is applied selectively to specific regions of the light guide plate where angular separation is needed for 3D effects. Rather than requiring precision across the entire display surface, the grating is localized to areas where light extraction and angular control are required, reducing overall manufacturing complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The light guide plate acts as an intermediary between the light sources and the diffraction grating. It distributes and conditions the light before it reaches the grating, making the light input more uniform and predictable. This intermediary function reduces the precision requirements for the grating itself, as the light guide plate pre-processes the light to optimize grating performance.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Adaptability or versatility

If color filters are used to transform white light into various colors, then the color display is achieved, but the energy efficiency decreases

Engineering Contradiction:
Improvecolor display capabilityVSAvoidenergy efficiency
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

Instead of using white light and filtering out unwanted wavelengths (which wastes energy), the patent extracts only the necessary color wavelengths directly from separate LED sources. Each LED emits its specific color wavelength efficiently without requiring filtering, thereby eliminating the energy loss associated with color filter absorption and improving overall energy efficiency.

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution allows for efficient backlighting of passive displays, enhancing their light emission capabilities and enabling the creation of 3D displays without the need for glasses, improving their practical applications and user experience.

Implementation Method 1

A multibeam diffraction grating is located at a surface of the plate light guide and is configured to diffractively couple out a portion of the guided light from the plate light guide

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

A multibeam diffraction grating-based color backlight system that uses laterally displaced light sources of different colors and a plate light guide with a multibeam diffraction grating

Methodology Applied
Scientific EffectDiffraction grating: Diffraction Grating

Implementation Method 3

a plate light guide with a multibeam diffraction grating to direct light beams

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3175267B1Multibeam diffraction grating-based color backlighting
Publication Date: 2020.12.30 LEIA INC
  • EP3175267B1 patent drawingFigure 1~2A
  • EP3175267B1 patent drawingFigure 2B~2C
  • EP3175267B1 patent drawingFigure 3~4A

AI summary

Multibeam diffraction grating-based color backlighting includes a plate light guide, a multibeam diffraction grating at a surface of the plate light guide, and light sources laterally displaced from one another in a direction corresponding to a propagation axis of the plate light guide. The light sources produce light of different colors. The plate light guide is to guide light from the light sources. The multibeam diffraction grating is to couple out a portion of the guided light using diffractive coupling as a plurality of light beams of different colors in a plurality of different principal angular directions.