Optical Sheet Laminate Angle Layout for Backlight Luminance Uniformity
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Solution Overview
Problem
Portable information equipment such as laptops and tablets face challenges in achieving sufficient luminance uniformity due to varying arrangements of point light sources and positional relationships among optical sheets in direct-type backlights.
Innovation Solution
An optical sheet laminate comprising multiple diffusion sheets with inverted quadrangular pyramid-shaped recesses and prism sheets with perpendicular extending directions, arranged at specific angles to improve luminance uniformity, and a method for manufacturing this laminate by evaluating and setting the recess angles for optimal luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a typical optical sheet laminate configuration is used, then the device structure is simple, but luminance uniformity is insufficient
Solution Approach 1:
The patent applies local quality by specifying different arrangement angles for diffusion sheets at different positions relative to the light source. The first diffusion sheet is arranged at a first angle while the second diffusion sheet is arranged at a second angle different from the first, optimizing light diffusion locally at each position to achieve overall luminance uniformity across the display panel.
Solution Approach 2:
The patent changes the arrangement angle parameter of diffusion sheets to improve luminance uniformity. By adjusting the angle at which diffusion sheets are arranged relative to the light source, the patent optimizes light distribution characteristics without changing the fundamental optical sheet laminate structure.
2Manufacturing precision
If multiple diffusion sheets with different arrangement angles are used, then luminance uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by specifying different arrangement angles for diffusion sheets at different positions relative to the light source. The first diffusion sheet is arranged at a first angle while the second diffusion sheet is arranged at a second angle different from the first, optimizing light diffusion locally at each position to achieve overall luminance uniformity across the display panel.
Solution Approach 2:
The patent applies asymmetry by arranging diffusion sheets at different angles rather than using symmetric identical arrangements. The first diffusion sheet and second diffusion sheet have different arrangement angles relative to the light source, creating an asymmetric configuration that optimizes light diffusion patterns for improved luminance uniformity.
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
Enhances luminance uniformity in backlight units and liquid crystal display devices, allowing for thinner designs and improved display quality.
Implementation Method 1
an optical sheet such as a diffusion sheet or a prism sheet is used to diffuse light emitted from a light source such as a light emitting diode (LED)
Implementation Method 2
two prism sheets having prism ridges perpendicular to each other are usually arranged above the diffusion sheet
Data Source
AI summary
An optical sheet laminate 100 to be incorporated into a backlight unit 40 includes a plurality of diffusion sheets 43 having a first surface 21a having a plurality of recesses 22 having a substantially inverted quadrangular pyramid shape, and a pair of prism sheets 44 and 45 having prism extending directions perpendicular to each other. An arrangement direction of the recesses 22 of one of the plurality of diffusion sheets 43 closest to the prism sheets 44 and 45 intersects with the prism extending directions at an angle of 0° or more and 20° or less, or 70° or more and 90° or less.