Extremely Thin Direct-Lit Backlight Lens With Coated Annular Hot Spot Control
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Solution Overview
Problem
Existing optical lenses for direct-lit backlight devices result in non-uniform light distribution and hot spots, necessitating a large number of LEDs to achieve adequate illumination, thereby increasing cost.
Innovation Solution
A novel optical lens design with a coated annular region and optional structures on the bottom surface, which refracts and absorbs light to achieve uniform light distribution without hot spots, using materials like PMMA and coatings to manage light angles and colors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional optical lenses are used in direct-lit backlight devices, then light distribution is achieved, but non-uniform light distribution and hot spots occur
Solution Approach 1:
The lens surface is divided into multiple zones with different optical properties: a central region and an annular region, each with specifically designed curvature radii and coating characteristics to control light distribution in different areas, thereby eliminating hot spots while maintaining uniform illumination
Solution Approach 2:
Different regions of the lens are assigned different functional characteristics - the central region has one set of optical parameters while the annular region has different parameters including specific curvature radii and selective spectral coatings, allowing each zone to optimize local light distribution and prevent overall non-uniformity
2Illumination intensity
If a large number of LEDs are used to achieve uniform illumination, then adequate lighting is provided, but cost increases
Solution Approach 1:
The optical lens is designed to perform multiple functions simultaneously: light redistribution, hot spot elimination, spectral management, and uniform illumination achievement, allowing a single lens component to replace what would otherwise require multiple LED sources and additional optical components
Solution Approach 2:
The lens utilizes controlled variations in curvature radius across different zones and selective spectral coating properties to transform the light distribution pattern, enabling uniform illumination output that reduces the total number of LEDs needed in the backlight system
3Quantity of substance
If the spot size of each LED is increased to decrease the number of LEDs, then cost is reduced, but light distribution control becomes more difficult
Solution Approach 1:
The lens design introduces dimensional variation in the form of curved surfaces with different radii in different zones, transforming the light distribution control from a one-dimensional approach to a multi-dimensional optical control system that manages both the number of LEDs and the distribution pattern effectively
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 lens design provides a wider transfer function with uniform light distribution, reducing the number of LEDs required and lowering overall costs by eliminating hot spots and enhancing luminance uniformity.
Implementation Method 1
an optical lens with a light incident surface and a light exit surface... The optical lens refracts and absorbs light to achieve uniform light distribution
Implementation Method 2
an optical lens with a coated annular region... The optical lens refracts and absorbs light to achieve uniform light distribution without hot spots
Data Source
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AI summary
Optical lens and light emitting device designs achieve uniform light distribution without producing a light "hot spot", with a benefit of reducing the number of light sources needed and overall cost for direct-lit backlight device. The optical lens includes coating portions or structures on the bottom surface thereof, and a backlight device, or other light emitting device, incorporating said lens, to produce a uniform distribution of light at a target surface. The disclosed lens and light emitting device are particularly useful when an extremely wide transfer function of backlight is needed.