Laser Local Dimming for Projector Contrast and 3D Separation

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Solution Overview

Problem

Existing 3D stereoscopic projection systems face challenges such as the need for expensive and fragile silver screens, viewer head orientation constraints, and limitations in contrast and color gamut due to current filtering methods.

Innovation Solution

The implementation of a laser imaging system with local dimming capabilities, utilizing a plurality of laser light sources directed at a spreader to create an overlapping pattern on a primary modulator, and a processing device to calculate energization levels based on image signals for enhanced contrast and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional 3D stereoscopic projection filtering methods are used, then left/right eye separation is achieved, but contrast and color gamut are limited

Engineering Contradiction:

Improve3D separation accuracyVSAvoidcontrast and color gamut

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The invention divides the projection system into multiple independent laser light sources (red, green, blue) that can be individually controlled and modulated. Each laser source projects its color component separately through the modulator, allowing precise control over color gamut and intensity without the limitations of traditional broadband filtering methods

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the fundamental parameter of light source type from broadband (lamp-based) to monochromatic (laser-based). This enables superior color separation and gamut because each laser emits a narrow spectral band, eliminating the need for aggressive filtering that degrades contrast and color accuracy

Inventive Principle:

Principle #35Parameter changes

2Reliability

If silver screen is used for polarization preserving, then linear polarization 3D works, but screen is expensive and fragile

Engineering Contradiction:

Improvepolarization preservationVSAvoidscreen cost and durability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces the mechanical/optical filtering approach (polarizers and silver screens) with a direct laser-based approach. By using individually controllable red, green, and blue lasers, the system achieves color separation and 3D effects without requiring polarization-preserving silver screens, thereby eliminating their associated costs and fragility issues

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Illumination intensity

If local dimming is implemented with multiple laser light sources, then contrast and performance are improved, but device complexity increases

Engineering Contradiction:

Improvecontrast and performanceVSAvoidnumber of laser light sources

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The invention combines multiple laser light sources (red, green, blue) into a single integrated projection path through the modulator. While the light sources are separate for color purity, they are merged in the optical path and controlled by a unified processing device that coordinates their activation and intensity levels to achieve local dimming effects

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If shutter glasses are used for temporal multiplexing, then 3D separation is achieved, but glasses are expensive and require batteries

Engineering Contradiction:

Improve3D separationVSAvoidglasses cost and maintenance

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces the active shutter glass system with a passive projection-based solution. By using individually controllable lasers that can be selectively activated for left and right eye images, the system achieves 3D separation through the modulator without requiring synchronized shutter glasses, eliminating their cost, battery requirements, and synchronization complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 improves contrast and overall performance of projection systems by allowing for localized dimming and efficient use of multiple laser light sources, reducing the need for expensive screens and enhancing color accuracy.

Implementation Method 1

a plurality of laser light sources directed at a spreader configured to spread light from each light source into an overlapping pattern on a primary modulator

Methodology Applied

Scientific EffectLaser: Laser

Data Source

PatentUS12206840B2Laser local dimming for projectors and other lighting devices including cinema, entertainment systems, and displays

Publication Date: 2025.01.21 DOLBY LABORATORIES LICENSING CORP

AI summary

Light from an array of laser light sources are spread to cover the modulating face of a DMD or other modulator. The spread may be performed, for example, by a varying curvature array of lenslets, each laser light directed at one of the lenslets. Light from neighboring and/or nearby light sources overlap at a modulator. The lasers are energized at different energy/brightness levels causing the light illuminating the modulator to itself be modulated (locally dimmed). The modulator then further modulates the locally dimmed lights to produce a desired image. A projector according to the invention may utilize, for example, a single modulator sequentially illuminated or separate primary color modulators simultaneously illuminated.