Optical Sheet Substrate Film for LCD Backlight Units
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Solution Overview
Problem
Current liquid crystal display (LCD) backlight units face inefficiencies in light utilization due to polarization components not aligning with the transmission axis of polarizing plates, leading to reduced luminance and energy consumption.
Innovation Solution
An optical sheet with a substrate film made of transparent resin, exhibiting optical anisotropy and specific phase advancing or retarding axial orientations, is introduced between the reflection polarizing plate and optical waveguide plate to convert polarization orientation of light into the transmission axis, enhancing light utilization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polarizing plate is used to achieve polarization in LCD, then polarization function is achieved, but light utilization efficiency deteriorates due to 50% light absorption
Solution Approach 1:
The patent changes the optical parameters of the substrate film by controlling its retardation value (within 50-200 nm) and phase advancing axial orientation angle (within 0-30 degrees relative to the short side orientation). This allows the substrate film to function as a polarization-controlling element that redirects polarization components without absorbing light, thereby improving light utilization efficiency while maintaining the necessary polarization function for the LCD display.
2Productivity
If the polarization orientation of light from the optical waveguide plate does not align with the transmission axis of the polarizing plate, then light can pass through the optical system, but luminance deteriorates due to mismatched polarization components
Solution Approach 1:
The substrate film acts as an intermediary element between the optical waveguide plate and the polarizing plate. It modifies the polarization state of light by converting the polarization components from the optical waveguide plate to align with the transmission axis of the polarizing plate, through its controlled retardation and phase advancing axial orientation. This ensures both efficient light transmission and high luminance output.
3Illumination intensity
If high luminance is achieved by improving the optical waveguide plate and lamp, then luminance improves, but the thin and light modeling capability deteriorates
Solution Approach 1:
The patent achieves high luminance by optimizing the optical parameters of the existing substrate film (retardation value and phase advancing axial orientation angle) rather than increasing the size or power of the light source and optical waveguide plate. This parameter optimization allows the backlight unit to maintain its thin and light design while achieving the desired high luminance performance.
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 solution significantly improves light utilization efficiency, enabling high-luminance and energy-saving capabilities while maintaining thin and lightweight LCD designs.
Implementation Method 1
substrate film which is made of a transparent resin and which is formed into a rectangular shape, and an optical layer overlaid on one face of the substrate film, which substrate film for the optical sheet having an optical anisotropy
Implementation Method 2
having an absolute value of the angle of the phase advancing axial orientation or the phase retarding axial orientation with respect to the short side orientation being π/16 or greater and 3π/16 or less
Data Source
Figure 1~2
Figure 3~4
Figure 5(a)~5(b)
AI summary
An object of the present invention is to provide a substrate film for an optical sheet, an optical sheet and a backlight unit capable of markedly enhancing utilization efficiency of rays of light and improving luminance. The present invention is characterized by being a substrate film for an optical sheet which is a made of a transparent resin and which is formed into a rectangular shape, which substrate film for the optical sheet having an optical anisotropy, and having an absolute value of the angle of the crystal orientation with respect to the short side orientation being π/16 or greater and 3π/16 or less. The crystal orientation preferably follows the phase advancing axial orientation. The substrate film for the optical sheet has a retardation value such that average intensity of transmitted beam IA becomes equal to or greater than 0.75 so as to be capable of converting polarization orientation of outgoing rays of light of the optical waveguide plate or the like to the transmission axial orientation of the polarizing plate or the like. The retardation value is preferably 140 nm or greater and 390 nm or less. The transparent resin is preferably polyethylene terephthalate or polycarbonate. The optical sheet of the present invention has the substrate film for the optical sheet, and an optical layer.