Pulse-Driven LED Light Source for Stable Color and Luminosity
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Solution Overview
Problem
Conventional light sources with phosphor-converted LEDs face issues of color shift and increased temperature due to saturation and thermal quenching when luminosity is varied, limiting the adjustability of light color and luminosity independently.
Innovation Solution
A light source driven by a pulse-shaped current, particularly pulse-width modulated, allows for independent control of luminosity and color by adjusting the energy density and pulse frequency, preventing thermal quenching and maintaining a constant color point through saturation management of luminescent materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the excitation density to the phosphors is increased to vary luminosity, then the luminosity of the light is changed, but the phosphors start to saturate due to ground state depletion or thermal quenching, causing the color of light to change
Solution Approach 1:
The patent applies periodic pulsed excitation instead of continuous excitation. By using pulses with duration shorter than the phosphor decay time, the system achieves luminosity control through pulse frequency modulation while allowing the phosphors to fully relax between pulses, preventing saturation and maintaining stable color characteristics.
Solution Approach 2:
The patent dynamically adjusts the excitation regime by controlling pulse width and frequency based on the phosphor decay characteristics. This dynamic control enables independent adjustment of luminosity and color by optimizing the temporal relationship between excitation pulses and phosphor response.
2Illumination intensity
If the power dissipation of the diode is increased to increase luminosity, then the luminosity is improved, but the temperature of the diode increases substantially
Solution Approach 1:
By using periodic pulsed excitation with duty cycle control, the system achieves average power reduction while maintaining peak luminosity during pulse periods. The intermittent operation allows thermal dissipation between pulses, preventing substantial temperature increase while controlling overall luminosity output.
3Stability of the object's composition
If the excitation density is increased to change the color of light, then the color is changed, but the luminosity also varies due to saturation effects
Solution Approach 1:
The patent uses periodic pulsed excitation where the pulse frequency is synchronized with or related to the phosphor decay time. This allows color control through spectral composition adjustment while maintaining stable luminosity through frequency-based control, decoupling color and luminosity adjustments.
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
Enables adjustable light color and luminosity without significant temperature increase, maintaining a stable color point and reducing thermal degradation, allowing for a wide range of colors to be produced with a single diode.
Implementation Method 1
a light source with at least one light emitting diode for emitting primary radiation
Implementation Method 2
said layer includes at least one luminescent material for converting the primary radiation into a secondary radiation
Data Source
AI summary
The present invention relates to a light source, which produces light leaving the light source with modifiable color and luminosity, with at least one light emitting diode for emitting primary radiation, comprising a layer connected with said diode, wherein said layer includes at least one luminescent material for converting the primary radiation into a secondary radiation.