Optical Lens Curvature for LED Backlight Uniformity
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Solution Overview
Problem
Backlight sources using light emitting diodes suffer from non-uniformity in display brightness due to small light emission angles and poor uniformity, leading to issues like bright dots and rings on display screens.
Innovation Solution
A light emitting device comprising a light emitting diode and a rotationally symmetric optical lens with specific concave and convex surfaces, where the symmetry axis passes through the center of the light emission surface, optimizing the distances and angles to distribute light uniformly, thereby increasing the light emission angle and reducing brightness fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional optical lens is used with LED, then the device structure is simple, but the light emission angle is small and brightness uniformity is poor
Solution Approach 1:
The optical lens is segmented into multiple distinct surfaces: a first light incidence surface, a second light incidence surface, a first light exit surface, and a second light exit surface. Each surface has specifically designed curvature radii to control light paths differently, achieving uniform brightness distribution through divided optical functions rather than a single complex surface
Solution Approach 2:
Different regions of the optical lens are assigned different optical properties through varying curvature radii. The first and second light incidence surfaces have different curvature characteristics, as do the first and second light exit surfaces. This local differentiation optimizes light extraction and emission in specific zones to eliminate bright dots and rings while maintaining overall simplicity
2Illumination intensity
If the light emission angle is increased to improve uniformity, then brightness distribution improves, but the device structure becomes more complex
Solution Approach 1:
The optical lens utilizes precisely controlled spherical curvatures on its surfaces. The first light incidence surface, second light incidence surface, first light exit surface, and second light exit surface each have specified curvature radii (R1, R2, R3, R4 respectively). These curved surfaces naturally broaden the light emission angle while maintaining a simple rotationally symmetric structure that avoids mechanical complexity
3Ease of manufacture
If conventional optical design is used, then manufacturing is easy, but bright dots and rings appear on display screens
Solution Approach 1:
Specific parameter ranges are established for the curvature radii of each surface to eliminate bright dots and rings. The first light incidence surface has curvature radius R1, the second has R2, the first exit surface has R3, and the second has R4. These parameter specifications maintain manufacturability through standard optical fabrication while precisely controlling light paths to prevent localized brightness anomalies
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 substantial uniformity in light intensity across a larger range, enhancing the light exit angle and reducing non-uniform brightness issues, such as bright dots and rings, in displays powered by the backlight source.
Implementation Method 1
the optical lens includes a light incidence surface and a light exit surface... the light incidence surface includes a concave surface, and the light exit surface includes a convex surface
Data Source
AI summary
The light emitting device includes a light emitting diode and an optical lens, the optical lens includes a light incidence surface and a light exit surface, the light incidence surface includes a first light incidence surface and a second light incidence surface, herein the ratios of the minimum ones to the maximum ones of the distances between respective points, on the first light incidence surface or the second light incidence surface, and the center of the light emission surface respectively belongs to [0.5, 0.7] or [0.683, 0.695]; and the convex surface includes a first light exit surface and a second light exit surface, herein the ratios of the minimum ones to the maximum ones of the distances between respective points, on the first light exit surface or the second light exit surface, and the center of the light emission surface respectively belongs to [0.771, 0.913], or [0.883, 0.921].