Cyan Phosphor-Converted LED Module for Stable Color Emission
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Solution Overview
Problem
Existing light emitting diodes (LEDs) struggle to achieve stable emission within the cyan region of the CIE 1931 color space, especially under varying operating temperatures and drive currents.
Innovation Solution
A phosphor-converted LED (pcLED) configuration using an LED emitting ultraviolet or blue light in conjunction with one or more phosphors, such as Sr4Al14O25:Eu2+, to produce a combined emission spectrum with a peak wavelength and full width at half maximum (FWHM) that satisfies specific criteria, ensuring the optical output falls within the desired cyan color region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional LEDs are used to emit cyan light, then the emission can be generated directly by the LED structure, but the color stability deteriorates under varying operating temperatures and drive currents
Solution Approach 1:
The patent changes the emission mechanism from direct LED emission to phosphor-converted emission, where the phosphor's emission characteristics (peak wavelength and FWHM) are selected to satisfy specific mathematical relationships. This parameter-based selection ensures that the down-converted light maintains stable color coordinates within the cyan region regardless of LED operating conditions
Solution Approach 2:
The patent introduces phosphor material as an intermediary between the LED and the final cyan emission. The phosphor absorbs blue light from the LED and re-emits cyan light with stable color properties, decoupling the color stability from the LED's direct emission characteristics and making the system resilient to temperature and current variations
2Stability of the object's composition
If phosphor-converted LEDs are used to achieve stable cyan emission, then color stability is improved, but the device complexity increases
Solution Approach 1:
The patent uses composite phosphor materials with specific emission characteristics (peak wavelength and FWHM satisfying defined relationships) to achieve the desired cyan color stability. The composite nature of the phosphor material allows tuning of emission properties to compensate for LED variations while maintaining a relatively simple overall device structure
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 pcLED configuration achieves stable and consistent cyan emission across a range of operating conditions, maintaining color stability within the defined cyan region of the CIE 1931 color space.
Implementation Method 1
one or more phosphors excited by the ultraviolet or blue light and in response emitting longer wavelength light
Data Source
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AI summary
A light emitting device comprises an LED emitting ultraviolet or blue light and one or more phosphors excited by the ultraviolet or blue light and in response emitting longer wavelength light to provide a combined phosphor emission spectrum having an emission peak at wavelength λpk with a full width at half maximum of FWHM. With λpk and FWHM expressed in nm, 525 nm ≥ λpk ≥ 0.039 * FWHM + 492.7 nm. The light emitting device may be used, for example, to signal the autonomous driving state of an automobile.