Light Guide Plate with Patterned Ridge Extraction for Backlight Uniformity
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Solution Overview
Problem
Conventional backlight systems for displays with passive pixels face challenges in efficiently distributing light without creating hotspots, as they often require large mixing distances, leading to increased volume consumption or hotspot issues when reducing mixing distance.
Innovation Solution
A light guide plate with varying ridge densities and patterns on its surface, including bumps and ridges, is used to distribute light evenly across the display, with different regions having distinct ridge densities and tapered endings to smooth transitions and reduce hotspot formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a large mixing distance is provided in the backlight unit, then light mixing is improved, but the volume consumption increases
Solution Approach 1:
The patent applies local quality by providing different ridge densities in different regions of the light guide plate. The first region has a first ridge density and the second region has a second ridge density that is different from the first ridge density. This allows light mixing to be optimized locally in each region without requiring a uniformly large mixing distance throughout the entire plate, thereby reducing overall volume consumption while maintaining effective light mixing where needed.
2Volume of moving object
If the mixing distance is reduced to decrease volume consumption, then volume efficiency is improved, but backlight hotspots occur
Solution Approach 1:
The patent prevents hotspots by implementing local quality variations through different ridge densities in different regions. The first region with the first ridge density and the second region with the second ridge density work together to distribute light extraction evenly, preventing concentration of light in specific areas (hotspots) even when the overall mixing distance is reduced for better volume efficiency.
Solution Approach 2:
The patent segments the light guide plate into multiple regions with different ridge densities. By dividing the plate into a first region and a second region, each with optimized ridge patterns for their specific locations, the system achieves effective light mixing and hotspot prevention without requiring a uniformly large mixing distance, thus reducing volume consumption while maintaining uniform backlight output.
3Ease of manufacture
If uniform ridge density is used across the light guide plate, then manufacturing is simplified, but light distribution uniformity deteriorates
Solution Approach 1:
The patent implements local quality by specifying that the light guide plate has a first region with a first ridge density and a second region with a second ridge density. This regional variation in ridge density optimizes light distribution uniformity across different areas of the plate, compensating for variations in light propagation and extraction that would occur with uniform ridge density, thereby achieving superior light uniformity while remaining manufacturable.
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 approach allows for improved backlight distribution, minimizing volume consumption while preventing hotspots, ensuring uniform illumination and enhancing the efficiency of light extraction for displays.
Implementation Method 1
Light scattering features such as bumps may be provided on the light guide plate. Light from the light-emitting diodes that is traveling within the light guide plate may be scattered upwards by the bumps to form backlight for a display.
Implementation Method 2
Light guide plates may also sometimes be provided with elongated ridges (sometimes referred to as lenticular features) that help extract backlight from the light guide plate.
Data Source
AI summary
A display may have a backlight unit with a row of light-emitting diodes that emit light into the edge of a light guide plate. The light guide plate may have opposing upper and lower surfaces. Backlight may be extracted from the light guide plate using an array of bumps on the lower surface and ridges on the upper surface. Ridge density may vary as a function of location across the display. Some of the ridges may be terminated along a meandering border between regions of differing ridge density. Ridge length and endpoint location can be dithered along borders between regions and ridge widths and thicknesses may be tapered down towards the endpoints. Ridges may be patterned to reduce the density of the ridges immediately adjacent the light-emitting diodes and thereby avoid over-extraction of the light at the light-emitting diodes.