Optical Sheet with Varying Scattering Layer Thickness
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Solution Overview
Problem
Conventional surface light source devices for liquid crystal display devices suffer from luminance unevenness due to the arrangement of emission members, leading to increased production costs and reduced light utilization efficiency, as existing solutions like light scattering layers along convex unit lenses do not sufficiently address the issue.
Innovation Solution
An optical sheet with a light scattering layer extending along the light exiting side surface of unit lenses, where the thickness of the scattering layer is greater at the apex than at the ends, effectively scattering light to reduce luminance unevenness and enhance light condensation, while allowing for independent control of optical paths in multiple directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple optical sheets are provided between emission members and transmission display unit, then light diffusion is improved, but device complexity and production cost increase
Solution Approach 1:
The patent combines multiple optical functions (light diffusion and light condensation) into a single optical sheet by integrating a light scattering layer with unit lenses. This merging approach eliminates the need for multiple separate optical sheets while achieving both light diffusion and directional control, thereby reducing device complexity and production cost.
Solution Approach 2:
The optical sheet is designed to perform multiple functions simultaneously: it acts as both a light diffusing element (through the scattering layer) and a light condensing element (through the unit lenses). This multi-functionality allows a single component to replace what would traditionally require multiple specialized optical sheets.
2Illumination intensity
If distance between emission members and transmission display unit is increased, then luminance unevenness is reduced, but display thickness increases
Solution Approach 1:
The patent applies local quality by creating regions with different light scattering properties within the optical sheet. The light scattering layer has varying thickness or density in different regions, allowing selective diffusion of light in specific areas while maintaining overall luminance uniformity without increasing display thickness.
3Ease of manufacture
If light scattering layer with uniform thickness is provided along unit lens surface, then manufacturing is simplified, but luminance unevenness reduction is insufficient
Solution Approach 1:
The patent implements local quality by making the light scattering layer's thickness or scattering properties vary at different locations. Specifically, the scattering layer has different characteristics at the apex portion versus the end portions of the unit lenses, enabling optimized luminance uniformity while maintaining manufacturability through controlled variation rather than complete complexity.
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 sheet significantly reduces luminance unevenness and enhances light condensation, providing uniform illumination and improved viewing angles without increasing the number of optical sheets, thus addressing the inefficiencies of conventional systems.
Implementation Method 1
a light scattering layer configured to scatter the light is provided to each unit lens
Implementation Method 2
a light exiting side lens part including unit lenses juxtaposed to one another, each unit lens projecting toward a light exiting side
Data Source
AI summary
An optical sheet is incorporated in a direct type surface light source device including a light source and is configured to allow light emitted from the light source to exit after changing a travel direction of the light. The optical sheet has a light exiting side lens part including unit lenses juxtaposed to one another and each unit lens is convex toward a light exiting side. A light scattering layer, configured to scatter the light, is provided to each unit lens. The light scattering layer extends along a light exiting side surface of each convex unit lens and constitutes the light exiting side surface of the unit lens. A thickness of the light scattering layer around an apex portion of each unit lens is greater than the thickness of the light scattering layer around each end portion of the unit lens.