3D Projector Using Circular Polarization Conversion

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Solution Overview

Problem

Existing three-dimensional projectors either require multiple projectors or costly active lenses to produce 3D images viewable with passive glasses, and active glasses have limitations such as energy dependency and high complexity.

Innovation Solution

A single projector system utilizing a light source with multiple LEDs, each equipped with a polarization conversion system comprising a linear polarizer and a rotatable wave plate, converting light to circular polarization and using a polarizing beam splitter to create offset images for passive glasses, reducing light loss with conic section reflectors and a dichroic color combiner for brighter images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single projector is used to produce 3D images, then the device complexity and cost are reduced, but the ability to produce images viewable with passive glasses is limited

Engineering Contradiction:

Improveprojector system complexityVSAvoidcompatibility with passive glasses

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The light source is segmented into multiple independent LED units, each with its own polarization conversion system. This allows each LED to generate sequentially offset images with different polarizations, enabling passive glasses compatibility while using a single projector body.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system uses periodic sequential emission of light from different LEDs, with each LED emitting for a specific time interval. The polarization conversion systems switch between different polarization states in synchronization with the sequential LED activation, creating the temporal separation needed for 3D imaging with passive glasses.

Inventive Principle:

Principle #19Periodic action

2Illumination intensity

If multiple projectors are used to produce 3D images for passive glasses, then full color 3D images are achieved, but the device complexity and size increase

Engineering Contradiction:

Improveimage brightnessVSAvoidprojector system complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

Multiple LED light sources with different polarizations are merged into a single projector system. The polarization conversion systems and beam splitters combine the light paths from multiple LEDs into a unified optical path, allowing multiple light sources to function within one projector body while maintaining their individual polarization characteristics for 3D imaging.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If active lenses are used in the projector, then 3D images are produced, but the cost and device complexity increase significantly

Engineering Contradiction:

Improve3D image production capabilityVSAvoidprojector system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces active liquid crystal lenses with a passive optical system using polarization conversion. Instead of using electrically controlled liquid crystal elements to switch between 3D and 2D modes, the system uses fixed polarization optics with sequentially activated LEDs, eliminating the need for complex active lens mechanisms while maintaining 3D image production capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If sequential images are projected quickly, then the 3D effect is achieved, but light loss occurs reducing image brightness

Engineering Contradiction:

Improveimage projection speedVSAvoidlight loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The system dynamically controls the activation timing of multiple LEDs to optimize light utilization. By coordinating the sequential activation of LEDs with the polarization conversion and beam splitting processes, the system maximizes the efficiency of each light pulse, reducing light loss while maintaining the sequential projection speed necessary for the 3D effect.

Inventive Principle:

Principle #15Dynamics

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 enables a compact, reliable, and energy-efficient single-projector system capable of producing bright, full-color 3D images viewable with passive glasses, suitable for small form factors like pico-projectors in portable devices.

Implementation Method 1

The wave plate of the PCS is rotated to a first position, and a first light is emitted by the LED in the first light source. This first light is converted to circular polarization.

Methodology Applied

Scientific EffectCircular polarization conversion: Polarisation

Implementation Method 2

This first light travels to the PBS where it is reflected onto the imaging device.

Methodology Applied

Scientific EffectPolarizing beam reflection: Reflection

Data Source

PatentUS8992024B2Three dimensional image projector with circular light polarization

Publication Date: 2015.03.31 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A system is provided for projecting a three-dimensional image. The system includes a light source and a polarization conversion system for converting light emitted from the light source to circular polarization. A beam splitter device is disposed adjacent the light source to receive light, and an LCoS image device is disposed adjacent the beam splitter device.