Backlight Device Half-Value Region Layout for Uniform Luminance
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Solution Overview
Problem
The unevenness of luminance in backlight devices increases as they become thinner and the number of LEDs mounted on them decreases, leading to reduced cost, which existing technologies have not adequately addressed.
Innovation Solution
A backlight device design that includes a substrate with light emitting elements, a diffuser plate, and reflection materials, where the elements are positioned to maintain an overlapping ratio of 20% or less and a ratio of less than half value regions to surrounding areas, ensuring that adjacent elements do not align in straight lines, thereby reducing luminance unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of LEDs is reduced to decrease cost, then manufacturing cost is reduced, but luminance uniformity deteriorates
Solution Approach 1:
The patent applies local quality by defining half value regions around each LED and controlling the overlapping ratio locally between adjacent LEDs. Instead of uniform spacing, the arrangement is optimized locally to ensure that the overlapping ratio of half value regions is 20% or less, which prevents excessive light concentration in specific areas and improves luminance uniformity even with fewer LEDs
Solution Approach 2:
The patent employs asymmetry by preventing three or more adjacent LEDs from being arranged in a straight line. This asymmetric arrangement distributes light more evenly across the display area, avoiding the formation of bright linear regions and improving overall luminance uniformity when using a reduced number of LEDs
2Length of moving object
If the backlight device is made thinner, then device thickness is reduced, but luminance uniformity deteriorates
Solution Approach 1:
The patent maintains luminance uniformity in thin devices by implementing local quality control through the half value region overlapping ratio. By ensuring that adjacent LEDs have an overlapping ratio of 20% or less in their half value regions, the patent optimizes light distribution locally, compensating for the reduced light diffusion capability in thinner device structures
Solution Approach 2:
The asymmetric arrangement principle prevents three or more adjacent LEDs from aligning in straight lines, which effectively eliminates bright linear regions that would be more pronounced in thinner devices. This asymmetric distribution ensures more uniform light diffusion across the display area even when the device thickness is reduced
3Manufacturing precision
If LEDs are arranged with higher density, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The patent changes the arrangement parameters by defining the half value region concept and setting the overlapping ratio parameter to 20% or less. This parameter-based approach provides clear design guidelines for LED placement, achieving luminance uniformity through quantifiable criteria rather than complex geometric patterns, thus reducing arrangement 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 design effectively reduces luminance unevenness to within ±2%, preventing visible light and dark variations and eliminating bright linear regions, while maintaining uniform brightness.
Implementation Method 1
a diffuser plate having an incident surface disposed facing to the surface of the substrate, and an emitting surface disposed on an opposite side of the incident surface, diffusing light incident on the incident surface from the plurality of light emitting elements, and emitting the diffused light from the emitting surface
Implementation Method 2
a plurality of reflection materials located between the substrate and the diffuser plate, each of the plurality of reflection materials being disposed above each of the plurality of light emitting elements
Data Source
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AI summary
The backlight device comprises a substrate; a plurality of light emitting elements disposed on a surface of the substrate; and a diffuser plate having an incident surface disposed facing to the surface of the substrate, and an emitting surface disposed on an opposite side of the incident surface, diffusing light incident on the incident surface from the plurality of light emitting elements, and emitting the diffused light from the emitting surface; wherein a half value region is defined in which light that is equal to or more than half of a peak value of a brightness of light emitted from one of the plurality of light emitting elements is incident on the incident surface, wherein the plurality of light emitting elements are disposed so that an overlapping ratio is 20 % or less, and wherein the overlapping ratio is a ratio of an area of an overlapping region to the area of the half value region defined around the one of the light emitting elements, and the overlapping region is a region overlapping the half value region defined around the one of the light emitting elements and a half value region defined around another one of the light emitting elements adjacent to the one of the light emitting elements.