Reflection Polarizing Plate Optical Sheet for LCD Luminance
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Solution Overview
Problem
Conventional liquid crystal display modules suffer from low light utilization efficiency due to the absorption and reflection losses caused by polarizing plates and optical sheets, leading to inadequate luminance, especially in immediate beneath type and opposed edge light type configurations.
Innovation Solution
An optical unit with a reflection polarizing plate and an optical sheet having a resin substrate film with specific crystal orientation and retardation values is introduced, enhancing light recycling by converting retroreflected polarization orientation, and a transparent media layer is added to increase the total reflection critical angle, thereby improving light utilization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polarizing plates are used to achieve polarization, then polarization function is provided, but light utilization efficiency deteriorates due to 50% absorption
Solution Approach 1:
The patent converts the harmful reflection loss into a beneficial recycling mechanism. By introducing a reflection polarizing plate with specific crystal orientation (π/8 to 3π/8), the retroreflected light that would normally be lost is redirected to pass through the liquid crystal layer again, converting the loss into useful light contribution to the display.
Solution Approach 2:
The patent recovers light that would otherwise be discarded. The optical sheet with specific crystal orientation recaptures retroreflected light and redirects it back through the liquid crystal layer, recovering light energy that would normally be lost at the polarizing plate interface.
2Productivity
If optical sheets with normal orientation are used to achieve light diffusion and refraction, then optical functions are provided, but polarization characteristics cannot be controlled
Solution Approach 1:
The patent applies local quality by introducing optical anisotropy specifically in the optical sheet layer while maintaining isotropic properties in other layers. The optical sheet has controlled crystal orientation (π/8 to 3π/8) to provide polarization control, while the liquid crystal layer maintains its switching function, creating localized functional differentiation.
Solution Approach 2:
The patent uses composite material structure combining isotropic and anisotropic materials. The optical sheet combines transparent substrate with optically anisotropic properties to simultaneously provide light diffusion and polarization control, creating a composite functional layer.
3Loss of energy
If light recycling is implemented to improve utilization efficiency, then energy loss is reduced, but polarization orientation inconsistency causes further loss
Solution Approach 1:
The patent changes the critical parameter of crystal orientation angle to π/8 to 3π/8 range, which optimizes the polarization conversion efficiency. This specific parameter range ensures that retroreflected light is properly oriented to pass through the liquid crystal layer effectively, maximizing light recycling while minimizing polarization-related losses.
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 significantly enhances light utilization efficiency and luminance in liquid crystal display modules by effectively recycling and redirecting retroreflected light, achieving energy savings and maintaining a thin, lightweight design.
Implementation Method 1
a reflection polarizing plate that splits reflected beams and transmitted beams on the basis of polarization characteristics
Implementation Method 2
Generally used polarizing plates 54, 55 provided in the liquid crystal display element 51 are those which exhibit absorption dichroism, i.e., absorption of one directional component of a light accompanied by transmission of remaining polarization components
Implementation Method 3
the optical sheet includes a resin substrate film having an optical anisotropy
Implementation Method 4
the absolute value of the angle of the crystal orientation of the substrate film with respect to the transmission axial orientation of the reflection polarizing plate is π/8 or greater and 3π/8 or less
Implementation Method 5
a transparent media layer filled between the reflection polarizing plate and the optical sheet
Data Source
AI summary
An object of the present invention is to provide an optical unit and a backlight unit which can markedly enhance utilization efficiency of rays of light and dramatically increase luminance, and which are suited for immediate beneath type liquid crystal display modules and the like. The optical unit of the present invention is a rectangular layered structural member having a reflection polarizing plate, an optical sheet superposed on the back face side of the reflection polarizing plate, and a transparent media layer filled between the reflection polarizing plate and the optical sheet. This optical sheet includes a resin substrate film having an optical anisotropy, and the absolute value of the angle of the crystal orientation of the substrate film with respect to the transmission axial orientation of the reflection polarizing plate is π/8 or greater and 3π/8 or less. The retardation value of the substrate film is preferably 70 nm or greater and 320 nm or less. The optical sheet preferably has an optical layer laminated on one face of the substrate film. The liquid crystal display module of the present invention has a liquid crystal display element, the optical unit, and an immediate beneath type backlight.