LED Optical Element Array for Thin Directional Illumination
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Solution Overview
Problem
Current illumination apparatuses using LEDs face challenges in reducing the size of LED elements while maintaining directional illumination, increasing efficiency, and minimizing electrical connection complexity and cost.
Innovation Solution
The development of an illumination apparatus with a catadioptric optical element array structure and light emitting element structure, where optical elements are aligned with LEDs to provide electrical connections integrated within the optical element array, reducing the need for external connections and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single macroscopic LED (1×1 mm) is used with a catadioptric optical element to achieve directional illumination (6 degree cone half angle), then the directional light output is achieved, but the device thickness increases to approximately 10 mm and the optical element size increases to 20 mm diameter
Solution Approach 1:
The invention divides a single macroscopic LED into an array of multiple smaller LED elements (e.g., 10×10 array of 0.1×0.1 mm LEDs). Each small LED is paired with a corresponding small optical element in the array. This segmentation allows the use of smaller optical elements with reduced thickness while collectively providing the required directional illumination output through the combined emission of multiple elements.
Solution Approach 2:
The invention transitions from a single-point light source in three-dimensional space to a two-dimensional array of light sources. By distributing the light emission across a planar array of multiple small LEDs, the system achieves directional illumination without requiring the large thickness that would be needed for a single macroscopic LED with equivalent optical elements.
2Productivity
If the LED size is reduced to increase current density capability and reduce junction temperature, then efficiency and luminance are improved, but the number of electrical connection steps increases and connection complexity increases
Solution Approach 1:
The invention merges the electrical connection function with the optical element structure. The optical elements in the array are integrated with electrical connection elements, allowing multiple small LEDs to be electrically connected through the optical element substrate or mounting structure. This integration reduces the number of separate electrical connection steps that would otherwise be required for each individual small LED.
Solution Approach 2:
The optical element structure serves multiple functions: it provides the optical function for directional illumination and simultaneously serves as the electrical connection substrate or mounting structure for the LED array. This multi-functionality eliminates the need for separate electrical connection components and steps, reducing overall system complexity.
3Productivity
If electrical connections are provided to LEDs on opposite surfaces to reduce current crowding, then current distribution is improved, but the electrical connection area increases and alignment complexity increases
Solution Approach 1:
The invention utilizes the third dimension (vertical depth) by providing electrical connections to LEDs on opposite surfaces of the substrate. This vertical arrangement in the z-dimension allows current to be distributed more effectively through the LED array without requiring increased lateral connection area, as the connections are stacked in different vertical planes rather than spreading out horizontally.
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 approach results in a more efficient and cost-effective illumination system with reduced current crowding, lower assembly costs, and improved optical throughput, enabling higher current densities and directional light output with reduced device thickness.
Implementation Method 1
Catadioptric elements employ both refraction and reflection
Implementation Method 2
Catadioptric elements employ both refraction and reflection, which may be total internal reflection (TIR) or reflection from metallised surfaces
Implementation Method 3
Catadioptric elements employ both refraction and reflection, which may be total internal reflection (TIR)
Data Source
AI summary
An illumination apparatus comprises a plurality of LEDs aligned to an array of directional optical elements wherein the LEDs are substantially at the input aperture of respective optical elements. An electrode array is formed on the array of optical elements to provide at least a first electrical connection to the array of LED elements. Advantageously such an arrangement provides low cost and high efficiency from the directional LED array.