Optical Sheet Protrusions Prevent Sticking and Scuffs
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Solution Overview
Problem
Conventional sticking preventive layers in liquid crystal display devices tend to produce scuffs on optical waveguide sheets due to their bead-based structure, leading to non-uniform luminance and sticking issues with other optical members.
Innovation Solution
An optical sheet with scattered, flattened semi-spherical or conical protrusions on its back face, designed to prevent sticking and scuffs by providing a smooth surface for contact with other optical members, while a diffraction grating shape on the back face enhances light diffusion and viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sticking preventive layer with bead-based protruding portions is used, then sticking is prevented, but scuffs are produced on the front face of the optical waveguide sheet
Solution Approach 1:
The patent applies spheroidality by forming the protruding portions with a spherical cap shape instead of bead-based structures. The curved surface of the spherical cap protruding portions provides a smooth contact interface that prevents sticking while avoiding the scuffing problem caused by angular bead protrusions. This geometric transformation resolves the contradiction between sticking prevention and harm to the optical waveguide sheet.
Solution Approach 2:
The patent changes the geometric parameters of the protruding portions by defining them as spherical caps with specific curvature radii (R1 between 1-10 μm, R2 between 1-5 μm). This parameter optimization ensures the protruding portions are sufficiently curved to prevent sticking but not so sharp as to cause scuffs, thereby resolving the technical contradiction.
2Reliability
If protruding portions with small curvature radius are used, then sticking is prevented, but scuffs are produced on the front face of the optical waveguide sheet
Solution Approach 1:
The patent optimizes the curvature radius parameters of the spherical cap protruding portions, specifying that R1 (outer curvature radius) should be between 1-10 μm and R2 (inner curvature radius) between 1-5 μm. This precise parameter control ensures the protruding portions maintain sufficient curvature to prevent sticking while avoiding excessive sharpness that would cause scuffs, thus resolving the contradiction between sticking prevention and surface quality.
3Reliability
If a conventional sticking preventive layer is used, then sticking is prevented, but uniformity of luminance is compromised due to scuffs
Solution Approach 1:
The patent employs spherical cap-shaped protruding portions that provide a smooth, uniform contact surface. This geometric design prevents the formation of scuffs on the optical waveguide sheet front face, thereby maintaining uniform light transmission and luminance uniformity while still preventing sticking. The spherical geometry ensures consistent optical properties across the entire surface.
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 solution effectively prevents sticking and scuffs, ensuring uniform luminance and improved light diffusion, thereby enhancing the performance and reliability of liquid crystal display devices.
Implementation Method 1
the protruding portions each have a flattened semi-spherical shape or a flattened conical shape with a rounded apex... the curved faces of the apexes (lower ends) of the plurality of protruding portions are comparatively smooth
Implementation Method 2
The optical sheet 104 has optical functions such as diffusion and refraction of the transmitted rays of light... a light diffusion sheet 105 which is disposed on the front face side of the optical waveguide plate 103 and primarily has a light diffusion function
Implementation Method 3
a prism sheet 106 which is disposed on the front face side of the light diffusion sheet 105 and has a refraction function toward a normal direction side
Implementation Method 4
a diffraction grating shape with multiple rows that are oriented in a single direction is provided on the back face in a region where the plurality of protruding portions are absent
Data Source
AI summary
An optical sheet for a liquid crystal display device includes a plurality of protruding portions provided scatteredly on a back face, in which the protruding portions each have a flattened semi-spherical shape or a flattened conical shape with a rounded apex. The protruding portions may each have a half spheroidal shape. An occupancy area ratio of the plurality of protruding portions may be no less than 2% and no greater than 80%. An average diameter of the protruding portions may be no less than 5 μm and no greater than 60 μm, and an average height of the protruding portions may be no less than 0.5 μm. A diffraction grating shape with multiple rows that are oriented in a single direction on the back face in a region where the plurality of protruding portions are absent.