Retro-reflective optical layer for backlit display parallax reduction

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Solution Overview

Problem

Backlit electronic displays are susceptible to parallax effects, causing image distortions when viewed from different angles due to the existing limitations in optical layers.

Innovation Solution

A retro-reflective optical layer is positioned between the backlight and the light modulator, comprising a single-layer array of lenses embedded in a matrix with optically-transmissive apertures on-axis and light-reflecting zones off-axis, configured to pass light at angles less than a threshold and reflect light greater than the threshold angle in a direction opposite to the incoming direction, reducing parallax errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional optical layers are used in backlit displays, then the display can be manufactured with standard components, but parallax effects cause image distortions when viewed from different angles

Engineering Contradiction:

Improveimage clarityVSAvoidparallax effects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The optical layer is segmented into multiple functional zones: a first portion with a first refractive index and a second portion with a second refractive index. This segmentation allows different regions to handle different angular ranges of light, with each zone optimized to direct light within specific viewing angles toward the viewer, thereby eliminating parallax effects while maintaining image clarity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the optical layer are assigned different local optical properties (different refractive indices) to optimize performance for specific viewing angles. The first portion is optimized for certain angular ranges while the second portion handles other angular ranges, creating locally optimized light directing capabilities that collectively eliminate parallax across the entire viewing spectrum

Inventive Principle:

Principle #3Local quality

2Reliability

If light is reflected back into the display at angles greater than the threshold, then parallax errors are reduced, but light loss increases without effective light recycling

Engineering Contradiction:

Improveparallax error reductionVSAvoidlight loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Light that would normally be lost by reflecting at angles greater than the threshold is converted into a beneficial resource. The optical layer is designed to reflect this light back into the display cavity where it can be redirected by the light guide and redistributed to other viewing angles, transforming what would be waste light into useful illumination that reduces parallax errors

Inventive Principle:

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

Solution Approach 2:

Instead of discarding light that reflects at angles greater than the threshold, the system recovers this light by redirecting it back into the display. The optical layer reflects this light back toward the light guide, which then redistributes it to appropriate viewing angles, effectively recovering energy that would otherwise be lost and improving overall display efficiency

Inventive Principle:

Principle #34Discarding and recovering

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

The solution effectively minimizes parallax errors by recycling light and maintaining image clarity across varying viewing angles, enhancing the optical efficiency and reducing distortions in backlit displays.

Implementation Method 1

reflect light incident thereon at an angle with respect to a normal to the retro-reflective optical layer of greater than φ in a direction opposite and generally parallel to an incoming direction of incident light

Methodology Applied

Scientific EffectRetro-reflection: Retroreflector

Implementation Method 2

a retro-reflecting optical layer comprising a single-layer array of lenses embedded in a matrix

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS7733568B2Retroreflective optical collimation layer and display devices incorporating same

Publication Date: 2010.06.08 DOLBY LABORATORIES LICENSING CORP

AI summary

A display comprises a backlight comprising a plurality of individually-controllable light emitters, a light modulator comprising a plurality of individually-controllable elements, and, a retro-reflective optical layer positioned between the backlight and the light modulator. The retro-reflective optical layer is configured to pass light incident thereon at an angle with respect to a normal to the retro-reflective optical layer of less than a threshold angle φ, and reflect light incident thereon at an angle with respect to a normal to the retro-reflective optical layer of greater than φ in a direction opposite and generally parallel to an incoming direction of incident light.