Lens with Concave and Convex Surfaces for Uniform Illumination
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Solution Overview
Problem
Existing light emitting modules, particularly direct-type backlights for liquid crystal displays, face challenges in achieving uniform illumination over large areas due to alignment issues between LEDs and lenses, leading to non-uniform light distribution and increased power consumption.
Innovation Solution
A light emitting module with a lens having a concave portion and an upper surface that includes a convex surface, allowing for primary refraction in the concave portion and secondary refraction in the upper surface, which disperses light extensively and increases alignment tolerance between LEDs and the lens, facilitating uniform light distribution over large areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a lens with a disk-shaped light orientation pattern is applied to disperse light, then light distribution is improved, but bright portions and dark portions are formed due to adjacent light beams crossing and overlapping
Solution Approach 1:
The lens surface is divided into multiple regions with different refraction characteristics. The convex surface is segmented into a central region and a peripheral region, each with different curvature radii, to control light refraction in different zones and eliminate bright and dark portions.
Solution Approach 2:
Different regions of the lens are given different optical properties. The central region has a first curvature radius while the peripheral region has a second curvature radius, allowing localized control of light refraction to achieve uniform illumination without bright or dark spots.
2Ease of manufacture
If the alignment between LED and lens is not precise, then manufacturing is easier, but light distribution becomes non-uniform
Solution Approach 1:
The lens design incorporates an elongated convex surface that inherently compensates for potential misalignment between LED and lens. This geometric feature acts as a buffer, reducing the impact of alignment errors on light distribution uniformity.
Solution Approach 2:
The convex surface is designed with an elongated shape rather than a symmetric circular form. This asymmetric geometry provides greater tolerance in certain alignment directions, making the system more robust to manufacturing variations.
3Area of stationary object
If a larger number of LEDs are densely arranged to cover a large area, then illumination coverage is improved, but power consumption increases
Solution Approach 1:
Instead of increasing the number of LEDs in the planar dimension, the patent uses a lens with an elongated convex surface that extends light distribution in a specific direction. This dimensional approach to light distribution reduces the need for additional LEDs.
Solution Approach 2:
A single lens structure performs multiple functions: it refacts light, distributes illumination over a large area, and provides alignment tolerance. This multi-functionality eliminates the need for additional components or increased LED density.
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 provides a uniform surface light source with increased alignment tolerance and ease of fabrication, reducing the formation of bright and dark portions, thus enhancing the overall light distribution and reducing power consumption.
Implementation Method 1
a lower surface having a concave portion on which light emitted from the light emitting diode chip is incident
Implementation Method 2
an upper surface from which the light incident on the concave portion is emitted. The upper surface includes a concave surface positioned in a central axis thereof
Data Source
AI summary
A lens including an upper surface having a curved portion having a changing curvature in a direction extending away from a central axis of the lens, and a lower surface having a concave portion disposed on the central axis of the lens. The concave portion of the lower surface includes an entrance disposed on a lower region of the concave portion and configured to receive light emitted from a light-emitting diode chip, and an upper end surface disposed on an upper region of the concave portion. The concave portion includes a width that narrows in a direction extending away from the entrance. The upper end surface is nonplanar.