Optical Waveguide Sheet Recessed Portions Backlight Uniformity
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Solution Overview
Problem
Liquid crystal display devices face issues with uneven luminance due to the adhesion of the optical waveguide sheet to the reflection sheet or top plate, which affects the uniformity of the backlight unit's thickness reduction in ultrathin portable terminals.
Innovation Solution
An optical waveguide sheet with recessed portions on its back face to scatter light uniformly and raised portions to prevent adhesion, eliminating the need for a sticking preventive layer and facilitating thickness reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the optical waveguide sheet is made thinner to reduce overall device thickness, then the thickness reduction goal is improved, but the sheet becomes more prone to adhesion to the reflection sheet or top plate causing uneven luminance
Solution Approach 1:
The patent introduces a dimensional feature (recessed portions) on the back surface of the optical waveguide sheet to prevent adhesion. By creating a three-dimensional surface profile with recessed areas, the design prevents direct contact between the waveguide sheet and reflection sheet while maintaining thin overall thickness. This dimensional approach resolves the contradiction by addressing adhesion prevention without increasing the sheet's thickness.
Solution Approach 2:
The back surface of the optical waveguide sheet is segmented into multiple recessed portions distributed across its area. This segmentation creates multiple separation points between the waveguide sheet and reflection sheet, preventing adhesion at any single location. The segmented structure ensures uniform light emission across the entire display area while maintaining the thin profile of the backlight unit.
2Reliability
If a sticking preventive layer is added to prevent adhesion, then luminance uniformity is improved, but device complexity and thickness increase
Solution Approach 1:
The patent merges the adhesion prevention function with the optical waveguide sheet structure itself by incorporating recessed portions directly into the sheet. Instead of adding a separate sticking preventive layer, the recessed portions are integrated as an inherent feature of the waveguide sheet, combining the structural and prevention functions into a single component. This reduces device complexity while maintaining luminance uniformity.
Solution Approach 2:
The optical waveguide sheet performs its own adhesion prevention function through the recessed portions built into its structure. The sheet does not require external assistance from separate preventive layers; its inherent three-dimensional surface profile provides the separation function. This self-service approach eliminates additional components and reduces overall device complexity.
3Weight of moving object
If the optical waveguide sheet is made thinner to achieve ultrathin portable terminal, then portability is improved, but adhesion to reflection sheet increases causing uneven light emission
Solution Approach 1:
The patent uses a three-dimensional surface profile with recessed portions on the back of the optical waveguide sheet to prevent adhesion. By utilizing the vertical dimension (depth of recessed portions) rather than increasing horizontal thickness, the design achieves adhesion prevention while maintaining the ultrathin profile required for portable terminals. This dimensional approach allows weight reduction without sacrificing luminance uniformity.
Solution Approach 2:
The recessed portions are strategically positioned at specific locations on the back surface of the optical waveguide sheet where adhesion is most likely to occur. By concentrating the separation structure at critical points rather than uniformly across the entire surface, the design prevents adhesion while minimizing the overall thickness and weight of the portable terminal.
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 optical waveguide sheet ensures uniform light emission and inhibits adhesion, achieving a reduction in thickness while maintaining luminance uniformity in edge-lit backlight units and portable terminals.
Implementation Method 1
a plurality of recessed portions falling toward the front face side... enabling the rays of light having entered the recessed portions to be scattered toward the front face side
Implementation Method 2
a plurality of raised portions each provided around each of the plurality of recessed portions and projecting toward the back face side... the optical waveguide sheet abuts the reflection sheet, the top plate or the like disposed on the back face side of the optical waveguide sheet at dispersed points by way of the plurality of raised portions
Implementation Method 3
rays of light that have been emitted from the light source 117 and have entered the optical waveguide sheet 111 propagate through the optical waveguide sheet 111
Data Source
AI summary
An optical waveguide sheet for use in an edge-lit backlight unit is provided, that allows rays of light to enter the end face and emits the rays of light from the front face substantially uniformly. The optical waveguide sheet includes, on the back side thereof: a plurality of recessed portions falling toward the front face side; and a plurality of raised portions each provided around each of the plurality of recessed portions and projecting toward the back face side. The optical waveguide sheet preferably has an average thickness of no less than 100 μm and no greater than 600 μm, and is preferably used as a light guide film. The optical waveguide sheet preferably has an average thickness of no less than 100 μm and no greater than 600 μm, and is preferably used as a light guide film.