Optical Waveguide Sheet with Protective Layer for Thin Backlight Units
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Solution Overview
Problem
The existing edge-lit backlight units in laptop computers face challenges in reducing thickness while maintaining uniform luminance, as the optical waveguide sheet can suffer scuffs when overlaid on metal top plates, leading to uneven luminance.
Innovation Solution
An optical waveguide sheet with a polycarbonate-based resin as the principal component and a protective layer made of acrylic resin on its back face, having an average thickness of 250 μm to 600 μm, and a relative refractive index less than 0.98, which prevents scuffs and ensures efficient light propagation and scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the optical waveguide sheet is overlaid on the metal top plate to reduce thickness, then the thickness of the backlight unit is reduced, but the optical waveguide sheet suffers scuffs leading to uneven luminance
Solution Approach 1:
A protective layer is introduced as an intermediary between the optical waveguide sheet and the metal top plate. This protective layer prevents direct contact and scuffing of the optical waveguide sheet while allowing the thin configuration to be maintained. The protective layer acts as a mediator that protects the optical surface from mechanical damage.
Solution Approach 2:
The optical waveguide sheet is constructed as a composite structure combining the optical waveguide layer with a protective layer. This composite structure integrates the optical functionality of the waveguide sheet with the protective properties of the additional layer, achieving both thinness and protection against scuffing.
2Reliability
If a protective layer is added to prevent scuffs, then the uniformity of luminance is maintained, but the thickness of the backlight unit increases
Solution Approach 1:
The protective layer is designed as a thin film structure that provides adequate protection against scuffing while minimizing the increase in overall thickness. The thin film configuration maintains the sleek, thin profile of the backlight unit while effectively protecting the optical waveguide sheet.
Solution Approach 2:
The thickness of the protective layer is optimized by carefully controlling the parameters of the protective layer, ensuring it is thick enough to prevent scuffing but thin enough to maintain the overall thinness of the backlight unit. This parameter optimization balances protection and thickness requirements.
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 allows for a reduction in thickness of the backlight unit while preventing luminance unevenness by using the protective layer to prevent scuffs and optimizing light reflection and scattering.
Implementation Method 1
rays of light that are emitted by the light source 117 and enter the optical waveguide sheet 111 propagate in the optical waveguide sheet 111
Implementation Method 2
a protective layer laminated on the back face of the optical waveguide layer, the protective layer containing an acrylic resin as a principal component
Implementation Method 3
rays of light that enter the scuffs are diffused, leading to the occurrence of the lack in uniformity of the luminance
Data Source
AI summary
The optical waveguide sheet of the present invention is an optical waveguide sheet for use in an edge-lit backlight unit of a liquid crystal display unit of laptop computers having a housing thickness of no greater than 21 mm, and includes an optical waveguide layer containing a polycarbonate-based resin as a principal component; and a protective layer laminated on the back face of the optical waveguide layer, the protective layer containing an acrylic resin as a principal component, wherein an average thickness of the optical waveguide sheet is no lower than 250 μm and no greater than 600 μm. An average thickness of the protective layer is preferably no less than 10 μm and no greater than 100 μm, and a relative refractive index of the protective layer with respect to the optical waveguide layer is preferably no greater than 0.95.