LED Backlight Layout for Uniform Edge Luminance
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Solution Overview
Problem
As backlight devices become thinner and the number of LEDs increases to reduce costs, the unevenness of luminance in these devices often increases, leading to suboptimal brightness distribution.
Innovation Solution
The backlight device employs a specific arrangement of LEDs with overlapping regions and a diffuser plate structure, where the LEDs are positioned to ensure an overlapping ratio of 20% or less and a half-value region definition, along with a reflective sheet to distribute light evenly, preventing linear bright regions and enhancing luminance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of LEDs is increased to reduce cost and thin the backlight device, then cost is reduced and thickness is decreased, but luminance uniformity deteriorates
Solution Approach 1:
The patent applies local quality by defining specific arrangement rules for different regions: the first arrangement rule applies to LEDs in the first region (away from frame), while the second arrangement rule applies to LEDs in the second region (near frame). This regional differentiation optimizes luminance uniformity for each specific area while maintaining overall uniformity across the entire backlight device.
Solution Approach 2:
The patent employs asymmetry by implementing different arrangement strategies for different spatial regions. The first arrangement rule (overlapping ratio 10-30%) differs from the second arrangement rule (overlapping ratio 30-50%), creating an asymmetric arrangement pattern that adapts to the different optical requirements of central versus peripheral regions, thereby improving overall luminance uniformity.
2Manufacturing precision
If light block members are disposed to reduce luminance unevenness at outer edges, then luminance uniformity is improved, but light loss increases
Solution Approach 1:
The patent changes the parameter of overlapping ratio to optimize luminance uniformity without light block members. By adjusting the overlapping ratio between adjacent LEDs to 10-30% in the first region and 30-50% in the second region, the patent achieves uniform luminance distribution while maintaining light efficiency, avoiding the light loss associated with traditional light block members.
3Manufacturing precision
If dot patterns with white pigment are disposed on diffuser plate to uniform brightness, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The patent changes the arrangement parameters of LEDs (overlapping ratio and positioning) to achieve luminance uniformity, replacing the need for complex dot patterns on the diffuser plate. This parameter-based approach simplifies the device structure while maintaining brightness uniformity across the display area.
Solution Approach 2:
The patent extracts the luminance uniformity function from the diffuser plate (by removing the need for dot patterns) and transfers it to the LED arrangement configuration. This extraction simplifies the diffuser plate structure while achieving the same uniformity effect through optimized LED positioning and overlapping ratios.
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 arrangement effectively reduces luminance unevenness to within ±2%, preventing visually noticeable light and dark areas and ensuring uniform brightness distribution, thus improving the overall performance of the backlight device.
Implementation Method 1
a diffuser plate having an incident surface disposed facing to the surface of the substrate, and an emitting surface disposed on the opposite side of the incident surface, diffuses light incident on the incident surface from the plurality of light emitting elements, and emits the diffused light from the emitting surface
Implementation Method 2
a plurality of reflection members disposed on portions of the incident surface respectively facing the plurality of light emitting elements so as to reflect light emitted from the light emitting element
Data Source
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AI summary
The backlight device has a substrate, a plurality of light emitting elements disposed on a surface of the substrate, a diffuser plate having an incident surface disposed facing to the surface of the substrate, and an emitting surface disposed on the opposite side of the incident surface, diffuses light incident on the incident surface from the plurality of light emitting elements, and emits the diffused light from the emitting surface, and a frame defining a light emitting region on which the plurality of light emitting elements are disposed, wherein the frame is disposed so as not to form a region less than the half value outside the light emitting elements disposed along the frame, and all of the plurality of light emitting elements are disposed so that a ratio less than the half value is 20% or less, the ratio less than the half value is a ratio of an area of the region less than the half value to an area of a surrounding region formed by connecting at least three light emitting elements disposed around the region less than the half value, and the region less than the half value is a region on which no half value regions of the plurality of light emitting elements are disposed.