LED Color Mixing Optics With Optical Feedback for Uniform Beams
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Solution Overview
Problem
Existing multi-color LED illumination devices face challenges in producing uniform color throughout the light beam, particularly in PAR form factors, due to large and inefficient light guides, and lack of optical feedback to compensate for LED aging, leading to non-uniform color over time.
Innovation Solution
A unique arrangement of multi-color LEDs with optical feedback, utilizing a substrate-mounted emitter module and a primary optics structure with photodetectors, combined with a double-sided exit lens and parabolic reflector, to ensure uniform color mixing and beam shaping across the entire beam angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional light guides are used for color mixing, then color mixing is achieved, but the device becomes large and inefficient
Solution Approach 1:
The patent extracts the color mixing function from the traditional large light guide and implements it through a compact multi-color LED array with integrated optics. The LED array directly generates mixed colors through multiple LED chips (red, green, blue, yellow) arranged in a compact configuration, eliminating the need for extensive light guide paths while achieving effective color mixing in a much smaller volume.
Solution Approach 2:
The patent transitions from one-dimensional light guide mixing to three-dimensional spatial mixing by arranging multiple colored LED chips in a compact array configuration. The light mixing occurs in multiple dimensions through the spatial arrangement of different colored LEDs and their optical interactions, enabling efficient color mixing without requiring long light guide paths.
2Device complexity
If simple diffusers are used for color mixing, then device complexity is reduced, but color accuracy deteriorates over time due to LED aging
Solution Approach 1:
The patent incorporates optical feedback mechanisms through photodetectors that monitor the light output from the LED array. The control system uses this feedback to detect changes in LED luminance and color characteristics over time, and automatically adjusts the drive currents to different LED chips to compensate for aging effects, thereby maintaining accurate color rendering throughout the product lifetime.
Solution Approach 2:
The patent dynamically changes the electrical parameters (drive currents) supplied to different colored LED chips based on their individual aging characteristics. By adjusting the current to each LED type (red, green, blue, yellow) independently, the system compensates for differential aging rates and maintains consistent color output despite component degradation over time.
3Adaptability or versatility
If multi-color LED arrays are used to produce saturated colors, then color gamut is improved, but uniformity of color across the beam deteriorates
Solution Approach 1:
The patent divides the illumination device into multiple segmented LED chip groups, each responsible for specific color components. The array includes separate red, green, blue, and yellow LED chips arranged in a structured pattern. This segmentation allows independent control and optimization of each color component while maintaining overall color uniformity through careful spatial arrangement and optical design.
Solution Approach 2:
The patent applies different optical characteristics to different regions of the LED array. Each LED chip type is positioned and optimized with specific optical elements (lenses, reflectors) tailored to its emission characteristics. This local optimization ensures that each color component contributes uniformly to the overall beam, achieving both wide color gamut and uniform color distribution across the entire illumination area.
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 uniform color across the entire beam angle, maintaining color accuracy over LED lifetime by compensating for changes in luminance through optical feedback, and improves color mixing efficiency.
Implementation Method 1
A plurality of photodetectors are mounted on the substrate and encapsulated within the primary optics structure
Implementation Method 2
a plurality of emission LEDs that are mounted onto a substrate and encapsulated within a primary optics structure
Implementation Method 3
N chains of serially connected LEDs with N LEDs in each chain, and each chain is configured to produce a different color of light
Implementation Method 4
The phosphor converted LEDs produce a greenish light
Data Source
AI summary
Illumination devices with improved color mixing optics are disclosed herein for mixing the colors produced by a multi-colored LED emitter module to produce uniform color throughout the entire beam angle of the output light beam, along with smoother edges and improved center beam intensity. Embodiments disclosed herein include a unique arrangement of multi-color LEDs within an emitter module, a unique exit lens with different patterns of lenslets on opposing sides of the lens, and other associated optical features that thoroughly mix the different color components, and as such, provide uniform color across the output beam exiting the illumination device. Additional embodiments disclosed herein include a unique arrangement of photodetectors within the primary optics structure of the LED emitter module that ensure the optical feedback system properly measures the light produced by all similarly colored emission LEDs.