Backlight Unit Polarized Light Specular Reflection
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Solution Overview
Problem
Liquid crystal displays (LCDs) face inefficiencies in light usage, energy consumption, and material degradation due to light absorption by polarization plates, leading to limitations in brightness and increased costs with existing polarization recycling structures.
Innovation Solution
A backlight unit with a light guide plate and polarization conversion units that maintain polarized light through specular reflection, using absorption and reflective polarizers, polarization rotators, and light path conversion members to enhance light efficiency and reduce the need for expensive polarization films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dual brightness enhancement film (DBEF) is used for polarization recycling, then light efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive DBEF films with inexpensive reflective polarizers that can be easily manufactured and integrated. The reflective polarizer structure uses simple layered materials (transparent substrate, reflective layer, and polarizing layer) that are much cheaper than DBEF technology, achieving polarization recycling without high manufacturing costs
Solution Approach 2:
The patent changes the polarization recycling mechanism from absorption-based (DBEF) to reflection-based (reflective polarizer). This parameter change in the working principle allows for simpler, cheaper materials while maintaining or improving light efficiency, as reflection loses less energy than absorption
2Productivity
If polarization plates are added to both sides of the display for polarization recycling, then light efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines the polarization conversion function and the light guiding function into a single integrated light guide plate structure. The polarized light is generated at the light guide plate itself through the reflective polarizer, eliminating the need for separate polarization plates on both sides of the display, thus reducing structural complexity while maintaining light efficiency
3Ease of operation
If light is absorbed by the polarization plate to adjust gray scale, then display function is achieved, but energy efficiency deteriorates
Solution Approach 1:
The patent converts the harmful light absorption (which causes energy loss and heat generation) into beneficial specular reflection. The light guide plate uses specular reflection to redirect light that would otherwise be absorbed, converting this 'harmful' light into useful display light, thereby improving energy efficiency while maintaining the gray scale adjustment function
4Ease of operation
If light is absorbed by the polarization plate, then gray scale adjustment is achieved, but material deterioration occurs due to heat
Solution Approach 1:
The patent eliminates the heat-generating light absorption process by using specular reflection instead. The reflective polarizer and light guide plate structure redirects light through reflection rather than absorption, converting the potentially harmful thermal effect into a beneficial non-thermal light redirection mechanism, thereby improving material durability while maintaining gray scale adjustment capability
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 achieves high light efficiency and polarization ratio, reducing material costs and energy consumption while maintaining polarized light emission, thus improving LCD performance and reducing manufacturing costs.
Implementation Method 1
the light guide portion configured to reflect light incident through the polarization conversion unit within the light guide portion
Implementation Method 2
the light emitting portions configured to emit light through specular reflection
Implementation Method 3
an absorption type polarizer configured to transmit a first polarized light from the light source and to absorb a second polarized light perpendicular to the first polarized light
Data Source
AI summary
Example embodiments relate to a backlight unit and a display apparatus employing the same. The backlight unit may include a light source; a polarization conversion unit configured to convert polarization of light incident from the light source; and a light guide plate configured to emit light incident through the polarization conversion unit. The light guide plate may include a plurality of light emitting portions configured to emit light through specular reflection. The light polarized by the polarization conversion unit may maintain its polarization state when it is subsequently emitted from the light guide plate.