Optical Waveguide Sheet Recessed Portions Prevent Adhesion
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Solution Overview
Problem
Liquid crystal display devices with edge-lit backlight units face issues with uneven luminance due to adhesion of the optical waveguide sheet to the reflection sheet or top plate, which affects the uniformity of light emission and requires a reduction in thickness for portable terminals.
Innovation Solution
An optical waveguide sheet with recessed portions on its back face for light scattering and annular raised portions to prevent adhesion, along with protruding portions for dispersed contact, ensuring uniform light emission and inhibiting adhesion-related luminance issues without the need for additional sticking preventive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the optical waveguide sheet is made thinner to reduce the thickness of the backlight unit, then the thickness requirement for portable terminals is met, but adhesion to the reflection sheet or top plate occurs causing uneven luminance
Solution Approach 1:
The optical waveguide sheet incorporates local structural variations including recessed portions and raised portions at specific locations on its back surface. These localized features create different surface heights that prevent adhesion at critical areas while maintaining the overall thin profile of the waveguide sheet, thus preserving luminance uniformity without increasing thickness.
Solution Approach 2:
The back surface of the optical waveguide sheet is segmented into multiple regions with different heights - recessed portions and raised portions - rather than being a flat surface. This segmentation distributes the contact points between the waveguide sheet and underlying components, preventing localized adhesion that would cause luminance unevenness while maintaining thin overall dimensions.
2Reliability
If a separate sticking preventive layer is added to prevent adhesion, then luminance uniformity is improved, but the thickness of the backlight unit increases
Solution Approach 1:
The sticking preventive function is merged into the optical waveguide sheet itself through the integration of recessed and raised portions on its back surface. This eliminates the need for a separate sticking preventive layer, as the waveguide sheet's own structural features provide the adhesion prevention function while maintaining the thin profile required for portable terminals.
Solution Approach 2:
The optical waveguide sheet performs multiple functions simultaneously: it guides light from the light source, provides structural support, and prevents adhesion through its recessed and raised portions. This multi-functionality eliminates the need for additional separate components, maintaining the thin overall thickness while achieving luminance uniformity.
3Weight of moving object
If the optical waveguide sheet is made thinner to reduce weight and thickness, then portability is improved, but structural integrity and light guiding efficiency may be compromised
Solution Approach 1:
The optical waveguide sheet incorporates local structural variations including recessed portions and raised portions at specific locations on its back surface. These localized features create different surface heights that prevent adhesion at critical areas while maintaining the overall thin profile of the waveguide sheet, thus preserving luminance uniformity without increasing thickness.
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 achieves uniform light emission and prevents adhesion-related luminance issues, facilitating a reduction in thickness of the backlight unit and portable terminals while maintaining structural integrity and light guiding efficiency.
Implementation Method 1
a plurality of recessed portions (16) falling toward a front face side
Implementation Method 2
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)
Implementation Method 3
a sticking preventive means includes: a plurality of annular raised portions (17) each provided around each of the plurality of recessed portions (16) and projecting toward a back face side; and a plurality of protruding portions (18) provided scatteredly in a region which does not include the annular raised portions (17)
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 sticking preventive means; and a plurality of recessed portions falling toward the front face side. The sticking preventive means: a plurality of annular raised portions each provided around each of the plurality of recessed portions and projecting toward the back face side; and a plurality of protruding portions provided scatteredly in a region which does not include the annular raised portions. The optical waveguide sheet is preferably for use as a light guide film having an average thickness of no less than 100 μm and no greater than 600 μm.