Light-Emitting Module Current Control for Chromaticity Stability
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Solution Overview
Problem
Light-emitting modules using semiconductor elements face challenges in maintaining desired light emission characteristics, such as luminous flux and chromaticity, due to shifts caused by temperature changes and voltage fluctuations, particularly when aiming for white light synthesis from blue, green, and red LEDs.
Innovation Solution
A light-emitting module comprising multiple semiconductor light-emitting elements (blue, green, and red LEDs) with current regulators and a control circuit that adjusts currents based on voltage fluctuations to maintain desired luminous flux and chromaticity, using differential amplifiers and a microcontroller to correct for changes in voltage and temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If semiconductor light-emitting elements are used to generate light, then light emission is achieved, but light output and chromaticity characteristics shift due to temperature and voltage changes
Solution Approach 1:
The patent implements a feedback control system where the control circuit continuously monitors the forward voltage of each semiconductor light-emitting element and dynamically adjusts the drive current to compensate for voltage drops. This closed-loop feedback mechanism detects changes in light emission characteristics and corrects them in real-time, preventing shifts in light output and chromaticity that would otherwise occur due to temperature changes and aging effects
Solution Approach 2:
The patent changes the operating parameters (drive current) of the semiconductor light-emitting elements based on detected voltage fluctuations. By dynamically adjusting current parameters in response to voltage changes, the system compensates for characteristic shifts and maintains stable light emission performance over time and across varying operating conditions
2Adaptability or versatility
If multiple semiconductor light-emitting elements with different peak wavelengths are used to synthesize white light, then desired chromaticity can be achieved, but precise control of luminous flux and chromaticity becomes difficult when characteristics shift
Solution Approach 1:
The patent segments the control of each semiconductor light-emitting element with different peak wavelengths into independent control channels. Each element's drive current is controlled separately based on its individual forward voltage characteristics, allowing precise independent adjustment of each wavelength component to achieve accurate white light synthesis and chromaticity control
Solution Approach 2:
The control circuit performs multiple functions: it monitors forward voltage, calculates compensation currents, adjusts drive currents, and maintains both luminous flux and chromaticity simultaneously. This multi-functional approach handles the complexity of controlling multiple wavelength components through a unified control system rather than separate control mechanisms
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 effectively stabilizes the luminous flux and chromaticity of the synthesized light, ensuring it approaches the initial state by dynamically adjusting currents in response to voltage changes, thereby maintaining the desired light emission characteristics without the need for additional sensors or temperature measurement components.
Implementation Method 1
a first current flowing through the first semiconductor light-emitting element to cause a first voltage drop over the first semiconductor light-emitting element
Implementation Method 2
The control circuit is configured to control at least one of the first current regulator to control the first current, the second current regulator to control the second current, or control the third current regulator to control the third current according to at least one of fluctuation of the first voltage drop, fluctuation of the second voltage drop, or fluctuation of the third voltage drop
Data Source
AI summary
A light-emitting module includes a light emitter including a first semiconductor light-emitting element, a second semiconductor light-emitting element, and a third semiconductor light-emitting element. A first current regulator is to supply the first current to the first semiconductor light-emitting element. The second current regulator is to supply the second current to the second semiconductor light-emitting element. The third current regulator is to supply the third current to the third semiconductor light-emitting element. A control circuit is configured to control at least one of the first current regulator to control the first current, the second current regulator to control the second current, or control the third current regulator to control the third current according to at least one of fluctuation of the first voltage drop, fluctuation of the second voltage drop, or fluctuation of the third voltage drop.