Polarizing Illuminator Layout for Single-Pass Light Recycling
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Solution Overview
Problem
Conventional display light sources are unpolarized, leading to significant light energy loss when polarized, and existing polarization recycling methods are inefficient due to random light propagation and multiple passes through recycling systems, which impede the effective illumination of liquid crystal on silicon (LCOS) displays.
Innovation Solution
A polarizing illuminator system that collimates unpolarized light, splits it into orthogonally polarized sub-beams, and uses a reflective polarizer to recycle light in a well-defined, collimated beam path, allowing for single-pass polarization recovery and efficient illumination of display panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional unpolarized light sources are used, then device simplicity is maintained, but light energy loss increases significantly when polarized
Solution Approach 1:
The patent implements a polarization recycling system where the reflective polarizer captures polarized light that would otherwise be lost and redirects it back through the liquid crystal layer. This recovery process allows the same light energy to be utilized multiple times, significantly reducing energy loss while maintaining a relatively simple device structure.
Solution Approach 2:
The system establishes a feedback loop where the reflective polarizer sends polarized light back to the liquid crystal layer for re-modulation. This feedback mechanism ensures that light energy is not wasted but continuously reused, improving overall system efficiency without requiring a complete redesign of the light source.
2Loss of energy
If existing polarization recycling methods are used with random light propagation, then some light recovery is achieved, but efficiency deteriorates due to multiple passes through recycling systems
Solution Approach 1:
The reflective polarizer is positioned at a specific location and oriented at a specific angle (45 degrees) to optimize the local light path. This localized optimization ensures that polarized light is efficiently redirected back through the liquid crystal layer in a controlled manner, improving both energy recovery and illumination efficiency simultaneously.
Solution Approach 2:
Instead of allowing light to propagate randomly through multiple recycling passes, the system inverts the approach by using a reflective polarizer to actively control and redirect light in a specific, well-defined path. This inversion transforms the random, inefficient process into a controlled, efficient single-pass recycling mechanism.
3Loss of energy
If multiple passes through recycling systems are used, then light recovery is increased, but device complexity and power consumption increase
Solution Approach 1:
The reflective polarizer enables continuous utilization of light energy by redirecting polarized light back through the liquid crystal layer in a single, continuous pass. This eliminates the need for multiple discrete recycling cycles, maintaining continuous useful action while reducing overall power consumption and system complexity.
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 light utilization efficiency and wall plug efficiency by ensuring that recycled light is directed efficiently to specific pixels, improving image quality and reducing power consumption in compact, energy-efficient display devices.
Implementation Method 1
a collimator configured to collimate light emitted by the light source
Implementation Method 2
a reflective polarizer configured to reflect light in a first polarization state and transmit light in a second polarization state
Implementation Method 3
a reflective polarizer configured to reflect light in a first polarization state
Implementation Method 4
a retarding wave plate disposed between the reflective portion of the first surface and the reflective polarizer, where the retarding wave plate is configured to rotate a polarization of at least one of the first sub-beam and the second sub-beam to match a polarization of the other of the first sub-beam and the second sub-beam
Implementation Method 5
Light recycling and conversion systems for display devices... uses a reflective polarizer to recycle light in a well-defined, collimated beam path
Data Source
AI summary
A polarizing illuminator includes a light source, a collimator for collimating a light beam emitted by the light source, a parallel plate having a first surface and a second surface disposed at an acute angle with respect to the light beam, the first surface including a transmissive portion and a reflective portion, and the second surface including a reflective polarizer configured to reflect one polarization of the light beam, transmit an orthogonal polarization of the light beam, and split the light beam into first and second orthogonally polarized sub-beams, and a retarding wave plate disposed between the reflective portion of the first surface and the reflective polarizer, wherein the retarding wave plate is configured to rotate at least one of the first sub-beam and the second sub-beam to a matched polarization, and the first and second sub-beams having the matched polarization propagate parallel to each other.