Rectangular Illumination Lens for Even Brightness Distribution
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Solution Overview
Problem
Conventional illumination modules of the direct type for backlight suffer from uneven brightness due to the arrangement of LEDs in a rectangular lattice, leading to bright and dark areas on the diffusion plate, and existing solutions either increase Fresnel reflection and total reflection or fail to effectively utilize illumination lights for rectangular ranges.
Innovation Solution
An illumination lens with a light receiving surface that is symmetric about the YZ-plane and XZ-plane, featuring a cross-sectional area that monotonously decreases with z-coordinate, and a light exit surface with a radius that adjusts to ensure even brightness distribution, using a specific function f(θ) to control the shape between an ellipse and a rhombus, and incorporating a reflecting surface to optimize light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If illumination lenses are arranged in a rectangular lattice, then the structure is simple and easy to manufacture, but brightness distribution becomes uneven with bright areas and dark areas generated
Solution Approach 1:
The patent applies asymmetry by changing the lens shape from the conventional symmetric circular/oval form to a rectangular shape with specific aspect ratio. This asymmetric geometry allows the lens to match the rectangular arrangement of LEDs, ensuring uniform light distribution across the diffusion plate without creating bright or dark areas, while maintaining ease of manufacture through the simple rectangular geometry.
2Illumination intensity
If the lens is upsized to prevent unevenness of illuminance, then brightness distribution improves, but the lens size increases and slimness is compromised
Solution Approach 1:
The patent applies local quality by optimizing the lens dimensions specifically for the rectangular arrangement of LEDs. The lens has a rectangular shape with specific aspect ratio (width-to-height ratio) that matches the LED layout, allowing each lens to cover its designated area uniformly without requiring excessive size. This localized optimization achieves even brightness distribution while maintaining compact lens dimensions.
3Illumination intensity
If rectangularly shaped illumination lenses are used, then brightness distribution improves, but incident angles increase and Fresnel reflection components increase
Solution Approach 1:
The patent applies parameter changes by carefully controlling the lens dimensions and shape parameters. The rectangular lens has specific width and height ratios that optimize the incident angles of light rays. By adjusting these geometric parameters, the patent reduces the average incident angle and minimizes Fresnel reflection components while maintaining the rectangular shape's advantage in achieving uniform brightness distribution.
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 solution achieves a slimmer and more even brightness distribution across the illumination module, reducing unevenness of illuminance and enhancing the effective use of illumination lights for rectangular ranges.
Implementation Method 1
incident angles of rays which come from the light source and exit from the lens, are larger than those in a lens of axial symmetry. Accordingly, components of Fresnel reflection and total reflection increase
Implementation Method 2
components of Fresnel reflection and total reflection increase
Implementation Method 3
lights from the LEDs are guided by a light-guiding plate to realize surface illuminant
Data Source
AI summary
An illumination lens includes a light receiving surface 101; and a light exit surface 103. When the axis of 101 is designated as Z-axis, a position of the bottom of the lens is designated as z=0 and X-axis and Y-axis are defined in a plane which contains z=0 and is perpendicular to Z-axis, 101 is symmetric about YZ-plane and XZ-plane and a cross-sectional area of a cross section of 101 parallel to XY-plane monotonously decreases with increase in z-coordinate. When the maximum value of z-coordinate on 101 is designated as d and a radius of the cross section of 103 at z=0 is designated as r, a point (x, y) on a cross section of 101 at z=0.3d is represented by(xa)2+(yb)2=f(θ)0≤θ≤π2(1)where a and b represent constants andθ=tan-1(yx)f(0)=f(π2)=1.0,andf(θ)≤1.0(2)1≤xa+yb(3)and there exists a point at whichf(θ)≦0.95anda<0.5r and b<0.5r.