LED Array Wiring Reduces Brightness Unevenness
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Solution Overview
Problem
Conventional semiconductor light emitting element arrays for automotive lighting suffer from uneven brightness distribution due to large wiring resistance and wide intervals between LED elements, leading to inadequate light emission in headlamps.
Innovation Solution
The semiconductor light emitting element array is designed with a unique electrode structure where wide wiring electrodes are placed along the long side of oblong LED elements, and narrow wiring electrodes are placed along the short side, reducing wiring resistance and interval width, and the LED elements are arranged with alternating brightness distributions to minimize unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If wiring electrodes are arranged in parallel to the long side of LED elements, then wiring resistance is reduced and brightness uniformity is improved, but device complexity increases due to the unique electrode configuration
Solution Approach 1:
The wiring electrode structure is segmented into multiple parts: first wiring electrodes extending in the first direction, second wiring electrodes extending in the second direction, and third wiring electrodes connecting adjacent LED elements. This segmentation allows each electrode to be optimized for its specific function, reducing overall wiring resistance while maintaining manufacturability through systematic segmentation of the electrical connection network.
Solution Approach 2:
Different regions of the LED array are provided with different wiring configurations tailored to local requirements. The first wiring electrodes are positioned to reduce resistance in the longitudinal direction, while second wiring electrodes address transverse current distribution. This local optimization ensures that each area receives appropriate electrical connectivity without requiring uniform complex structure throughout the entire array.
2Power
If the number of LED elements is increased to achieve high power, then total light output increases, but the proportion of non-light-emitting regions increases causing uneven brightness distribution
Solution Approach 1:
Adjacent LED elements are electrically connected through third wiring electrodes that bridge the non-light-emitting regions between elements. This merging of electrical pathways ensures that current flows uniformly across the entire array, including through the inter-element regions, thereby reducing the impact of non-light-emitting areas and achieving more uniform brightness distribution across the high-power multi-element array.
Solution Approach 2:
The wiring electrode arrangement introduces a two-dimensional electrical connection network with electrodes extending in both first and second directions, rather than simple linear connections. This dimensional expansion of the electrical pathway allows current to distribute more evenly across the array surface, compensating for the presence of non-light-emitting regions between elements and achieving uniform brightness in high-power configurations.
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 configuration significantly reduces brightness unevenness within each LED element and in the overall array, resulting in a more uniform light emission and reduced shadow effects in projection images.
Implementation Method 1
an n-type semiconductor layer 21, an active layer 22 and a p-type semiconductor layer 23 in this order from the substrate 30 side
Data Source
AI summary
A light emitting element in use for an LED array comprises an electrode layer, a semiconductor light emitting layer consisting of a p-type semiconductor layer, an active layer and an n-type semiconductor layer, a first wiring layer formed along and in parallel to one side of the semiconductor light emitting layer, and a plurality of second wiring layers extending from the first wiring layer to the semiconductor light emitting layer and electrically connected to the n-type semiconductor layer on a surface of the semiconductor light emitting layer, wherein a plane shape of the semiconductor light emitting layer comprises two short sides including a portion inclined from a line perpendicular to a upper and a lower sides, and a vertical line from a vertex where the upper side and the short side meet crosses the lower side of the adjacent light emitting element.