Reflective Display Module Light Guide Plate Polarization Control
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Solution Overview
Problem
Conventional display projectors using LCOS panels are bulky due to the large space occupied by polarizing beam splitters, resulting in a long distance between the image-forming lens and the LCOS panel, which increases the thickness and volume of the projector.
Innovation Solution
A display module comprising a light guide plate, an optical structure, and a reflective polarizer that guides the illumination beam to a reflective display unit, reducing the thickness and volume by altering the propagation direction of the light beam and using a reflective polarizer to filter the modulated beam into an image beam, thereby minimizing the need for a polarizing beam splitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polarizing beam splitter (PBS) is used to guide the illumination beam to the LCOS panel, then the polarization state can be controlled, but the device occupies a large space and increases the thickness of the display module
Solution Approach 1:
The patent extracts and removes the polarizing beam splitter (PBS) from the optical path by using a reflective polarizer positioned at the exit surface of the light guide plate. This eliminates the need for the bulky PBS component while maintaining polarization control functionality, directly resolving the contradiction between reliable polarization control and reduced device thickness.
Solution Approach 2:
The invention changes the dimensional arrangement of the polarization control mechanism by placing the reflective polarizer at the exit surface of the light guide plate rather than using a separate beam splitter component. This repositioning in the optical path allows for compact integration and reduces the overall thickness of the display module while maintaining functional effectiveness.
2Reliability
If the beam splitting plane of the PBS is inclined at 45 degrees to guide the beam, then the polarization filtering can be achieved, but the distance between the image-forming lens and the LCOS panel becomes long
Solution Approach 1:
The patent removes the PBS component entirely from the system and replaces it with a reflective polarizer integrated at the light guide plate's exit surface. This extraction eliminates the need for the 45-degree inclined beam splitting plane, thereby reducing the optical path length and the distance between the image-forming lens and the LCOS panel while maintaining effective polarization filtering.
Solution Approach 2:
The reflective polarizer is merged with the light guide plate structure, combining the light guiding function and the polarization filtering function into a single integrated component. This merging eliminates the need for separate PBS optics and reduces the overall optical path length, directly addressing the contradiction between effective polarization filtering and minimized lens-to-display distance.
3Reliability
If a light guide plate with large thickness is used to guide the illumination beam, then the light distribution can be uniform, but the overall volume of the display device increases
Solution Approach 1:
The patent employs a thin light guide plate with integrated optical structures (such as microlens arrays or scattering particles) on its exit surface to achieve uniform light distribution. This thin-film approach maintains effective light guiding and uniformity while significantly reducing the plate thickness and overall device volume, resolving the contradiction between light distribution quality and compactness.
Solution Approach 2:
The light guide plate is designed as a composite structure combining transparent material with embedded or surface-mounted optical elements (microlenses, scattering particles, or diffraction patterns). This composite design enables effective light redistribution and uniform illumination from a thin plate, achieving the desired light distribution uniformity without increasing the device volume.
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 results in a thinner and more compact display module with improved light efficiency and uniformity, reducing the overall volume of projectors and other display devices like HMDs and HUDs.
Implementation Method 1
The illumination beam enters the light guide plate through the incident surface
Implementation Method 2
The light guide plate has a first surface, a second surface opposite to the first surface, and an incident surface connecting the first surface and the second surface. The illumination beam enters the light guide plate through the incident surface.
Implementation Method 3
The optical structure is connected to the light guide plate and configured to change a propagation direction of the illumination beam
Implementation Method 4
The reflective display unit is capable of modulating a polarization state of the illumination beam to form a modulated beam
Implementation Method 5
The reflective display unit is capable of modulating a polarization state of the illumination beam
Implementation Method 6
The first surface is disposed between the second surface and the reflective polarizer, and the reflective polarizer filters the modulated beam into an image beam
Implementation Method 7
the reflective polarizer filters the modulated beam into an image beam
Data Source
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AI summary
A display module is provided. A light source is configured to provide an illumination beam. A light guide plate has a first surface, a second surface opposite to the first surface, and an incident surface connecting the first surface and the second surface. The illumination beam enters the light guide plate through the incident surface. An optical structure is connected to the light guide plate and configured to change a propagation direction of the illumination beam. A reflective display unit is capable of modulating a polarization state of the illumination beam to form a modulated beam. The second surface is disposed between the reflective display unit and the first surface. The first surface is disposed between the second surface and a reflective polarizer, and the reflective polarizer filters the modulated beam into an image beam.