Downwardly Convex Prism Sheet for LCD Light Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing edge-lit backlight units for liquid-crystal display apparatuses face challenges in achieving sharp directivity and high light utilization efficiency due to complex configurations and color tints, particularly when using upwardly convex prism sheets and reflective polarizing plates.
Innovation Solution
A configuration featuring a downwardly convex prism sheet, a ¼-wavelength plate, and a reflective polarizing plate, integrated with each other, is used on the exit surface of a light guide plate to improve light directivity and utilization efficiency, while reducing air interfaces and suppressing sidelobe light, and the ¼-wavelength plate is designed to exhibit reverse wavelength dispersion characteristics with refractive-index isotropy materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an upwardly convex prism sheet is used with a reflective polarizing plate to improve light utilization efficiency, then light utilization efficiency is improved, but device complexity increases and color tints occur
Solution Approach 1:
The patent inverts the conventional upwardly convex prism sheet to a downwardly convex prism sheet. This inversion simplifies the overall configuration by eliminating the need for a reflective polarizing plate, while still achieving high light utilization efficiency through the modified prism geometry that redirects light more effectively.
Solution Approach 2:
The patent removes the reflective polarizing plate from the conventional configuration, extracting this component entirely. The downwardly convex prism sheet alone achieves the desired light control function, reducing device complexity and eliminating the color tints associated with the reflective polarizing plate.
2Manufacturing precision
If multiple layers (prism sheet, ¼-wavelength plate, reflective polarizing plate) are stacked to improve directivity and light utilization, then sharp directivity and high contrast are achieved, but device complexity increases
Solution Approach 1:
The patent merges the functions of the downwardly convex prism sheet, ¼-wavelength plate, and reflective polarizing plate into a single integrated structure. The downwardly convex prism sheet performs both the light redirecting function of the original prism sheet and the polarizing function of the reflective polarizing plate, eliminating the need for separate layers while maintaining sharp directivity.
Solution Approach 2:
The downwardly convex prism sheet serves multiple functions simultaneously: it controls light directivity, manages polarization states through its interaction with the ¼-wavelength plate, and eliminates the need for a reflective polarizing plate. This multi-functionality reduces the total number of layers while achieving the desired optical performance.
3Loss of energy
If a reflective polarizing plate is used to reflect exiting light components back into the light guide plate, then light utilization efficiency is improved, but color tints occur in the display
Solution Approach 1:
The patent inverts the prism orientation to downwardly convex, which changes the light reflection and redirection path. This inversion eliminates the need for a reflective polarizing plate that causes color tints, while the ¼-wavelength plate compensates for polarization effects to maintain high light utilization efficiency without introducing color distortion.
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 configuration secures sharp directivity and high contrast with a simple setup, enhances light utilization efficiency, and improves color tints by effectively converting polarized light components and reducing color shifts, resulting in a high-efficiency and high-contrast liquid-crystal display apparatus.
Implementation Method 1
a 1/4-wavelength plate is provided between the prism sheet and the reflective polarizing plate, between the prism sheet and the light guide plate, or between the light guide plate and a reflective sheet
Implementation Method 2
a reflective polarizing plate is disposed instead of a linear polarizing plate reflect the exiting light components of a backlight unit which have otherwise been absorbed by the linear polarizing plate so as to re-enter a light guide plate
Implementation Method 3
correcting the directivity of the light using a prism sheet so that the light is directed in a front-surface direction of the exit surface
Data Source
AI summary
Sufficiently sharp directivity can be secured with a simple configuration in a configuration that improves the efficiency of utilizing the light exiting from a primary light source using a reflective polarizing plate. A backlight unit (2) supplies light exiting from an exit surface of a light guide plate (12) to a liquid-crystal display panel (3) via a reflective polarizing plate (16) after correcting directivity of the exiting light using a prism sheet (14) having a downwardly convex shape. A ¼-wavelength plate (15) is provided between the prism sheet (14) and the reflective polarizing plate (16), between the prism sheet (14) and the light guide plate, or between the light guide plate and a reflective sheet disposed on a surface of the light guide plate opposite to the prism sheet (14).