Light Guide Plate with Birefringent Polarization Separation
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Solution Overview
Problem
Current liquid crystal display (LCD) technologies face limitations in light utilization efficiency due to the inefficiencies of absorption-type polarizers, which result in low luminance and inadequate reuse of polarized light, and existing reflective polarizers do not effectively enhance light utilization or polarization separation.
Innovation Solution
A light guide plate is designed with a polarization separation layer and an angle improvement layer, utilizing fibers with birefringence and isotropic matrix layers to efficiently emit light by separating and redirecting polarized light, thereby improving light utilization and reducing in-plane non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an absorption-type polarizer is used to control light direction, then light transmission in the transmission axis direction is achieved, but light utilization efficiency cannot exceed 50% due to absorption of other light components
Solution Approach 1:
The patent replaces the absorption-type polarizer with a reflective polarizer that works on the principle of reflection rather than absorption. The reflective polarizer reflects polarized light back toward the backlight while transmitting light in the transmission axis direction, thereby inverting the conventional approach of light control and achieving superior light utilization efficiency without the 50% loss inherent in absorption-type polarizers.
Solution Approach 2:
The patent changes the fundamental optical parameter from absorption to reflection. By using a reflective polarizer with specific reflection and transmission characteristics, the system transforms how light is manipulated - instead of absorbing unwanted polarizations, the system reflects them back, fundamentally changing the light control mechanism to achieve higher efficiency.
2Use of energy by moving object
If a brightness enhancement film (DBEF) is used as a reflective polarizer, then polarization separation and light utilization efficiency are improved, but manufacturing cost increases due to the complex stacked polymer film structure
Solution Approach 1:
The patent replaces the expensive brightness enhancement film with a cost-effective reflective polarizer that can be manufactured as a thin film coating or integrated layer. This alternative achieves the same polarization separation and light utilization efficiency without requiring the complex hundreds-of-layers stacked polymer structure, thereby significantly reducing manufacturing cost while maintaining performance.
Solution Approach 2:
The patent employs a composite structure combining the reflective polarizer with the light guide plate and diffuser layers to achieve the desired optical performance. This composite approach integrates multiple functions into a unified structure that is both cost-effective and manufacturable, avoiding the need for separate expensive brightness enhancement films.
3Loss of information
If polarization separation is achieved by scattering light forward, then polarization separation is realized, but light utilization efficiency does not increase significantly since scattered light is emitted externally and becomes extinct
Solution Approach 1:
The patent converts the harmful effect of forward scattering that leads to light loss into a beneficial mechanism by using a reflective polarizer. Instead of allowing polarized light to scatter forward and be lost, the reflective polarizer reflects this light back toward the backlight, transforming what would be waste into useful light that can be reused, thereby simultaneously achieving polarization separation and high light utilization efficiency.
Solution Approach 2:
The patent ensures continuous useful action by reflecting polarized light back into the optical system rather than allowing it to escape. This creates a continuous cycle where light is repeatedly utilized - transmitted when needed, reflected when polarized, and reused multiple times - maintaining continuous productive action rather than allowing light to be lost after a single pass.
4Loss of information
If light is scattered in multiple directions by fibers with birefringence, then polarization separation is achieved, but in-plane non-uniformity occurs and front luminance is reduced
Solution Approach 1:
The patent applies local quality by positioning the reflective polarizer at specific locations within the optical system - particularly at the light incident surface of the light guide plate. This localized placement ensures that polarization separation occurs precisely where needed, while the reflected light is directed back into the light guide plate to maintain uniform front luminance distribution, avoiding the in-plane non-uniformity caused by scattered light emission.
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 enhances light emission efficiency, increases front luminance, and reduces power consumption while expanding the viewing angle, providing a more uniform and efficient light distribution for LCDs.
Implementation Method 1
a first fiber having birefringence, with an ordinary ray refractive index, no1 and an extraordinary ray refractive index, ne1
Implementation Method 2
the ordinary ray refractive index is measured perpendicular to the length direction of the fiber
Data Source
AI summary
The present invention provides a light guide plate for emitting light radiated from a light source disposed at a side of the light guide plate. The light guide layer has a light incidence side for internally introducing light emitted from the light source at the side thereof; a polarization separation layer comprising a first matrix layer and a first fiber having birefringence and disposed more toward the light emission side than the light guide layer; a low refractive index layer having a lower refractive index than the refractive index of the first matrix layer; and an angle improvement layer comprising a second matrix layer having a second fiber disposed inside the second matrix layer.