Optical Sheet Laminate Angle Layout for Uniform Backlight Luminance
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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 recesses and prism sheets with perpendicular extending directions, arranged at specific angles to improve luminance uniformity, and a method to determine these angles based on evaluation results for optimal alignment.
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 different diffusion sheets based on their position relative to light sources. The first diffusion sheet closest to light sources is arranged at 0° to 10° to maximize light extraction, while other diffusion sheets are arranged at 45° to optimize overall luminance uniformity across the display surface.
Solution Approach 2:
The patent changes the arrangement angle parameter of diffusion sheets to improve luminance uniformity. By adjusting the arrangement angles from conventional fixed values to optimized values (0°-10° for first sheet, 45° for others), the patent achieves better light distribution without changing the fundamental optical sheet laminate structure.
2Manufacturing precision
If multiple diffusion sheets are added to improve luminance uniformity, then luminance uniformity improves, but the device thickness increases
Solution Approach 1:
The patent uses partial action by selectively optimizing only the critical diffusion sheets (first sheet at 0°-10° and second sheet at 45°) rather than adjusting all sheets. This targeted approach achieves sufficient luminance uniformity improvement while minimizing the total number of sheets and overall thickness.
3Manufacturing precision
If diffusion sheets are arranged at standard angles, then manufacturing is simple, but luminance uniformity is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-determining the optimal arrangement angles (0°-10° for first sheet, 45° for second sheet) during the design phase. These predetermined angles are then used as manufacturing specifications, allowing standard production processes to achieve the optimized luminance uniformity without requiring complex real-time adjustments.
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 displays by optimizing the arrangement of diffusion and prism sheets, allowing for thinner designs and improved light diffusion.
Implementation Method 1
an optical sheet laminate to be incorporated into a backlight unit includes a plurality of diffusion sheets each having surfaces, at least one of which has a plurality of recesses having a substantially inverted quadrangular pyramid shape
Implementation Method 2
a pair of prism sheets having prism extending directions perpendicular to each other
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 polygonal 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.