Anti-Parallel Laser Diode Driver Using Resonant AC Current Control
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Solution Overview
Problem
Existing laser-based lighting systems require complex multi-channel drivers to control color point and color rendering index (CRI), necessitating multiple connections and intricate control, which complicates the system design.
Innovation Solution
A parallel resonant converter with anti-parallel lighting loads and a capacitor in parallel with the loads, controlled by a controller to manage current distribution through frequency-dependent impedance, allowing simplified control and direct AC voltage utilization without rectification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple primary color lasers are used to make white light (e.g. RGB or RGBY combinations), then the color rendering index (CRI) and color point control are improved, but the device complexity increases due to multi-channel drivers and wiring
Solution Approach 1:
The patent combines multiple lighting loads (laser diodes and LEDs of different colors) into a single anti-parallel configuration that can be controlled by a single driver channel. The first lighting load (e.g., blue laser diode) and second lighting load (e.g., red LED) are connected in anti-parallel, allowing them to be driven simultaneously by one AC voltage output from the parallel resonant converter, eliminating the need for separate driver channels for each color source.
Solution Approach 2:
The single driver channel serves multiple functions by controlling both the blue laser diode and red LED through the anti-parallel configuration. The driver can independently adjust the current to each load type while using the same control signal, making the driver universal for controlling multiple color sources without requiring separate dedicated drivers for each channel.
2Adaptability or versatility
If additional red laser is used to increase red spectral content, then the color rendering index (CRI) is improved, but the device complexity increases due to advanced multi-channel driver requirements
Solution Approach 1:
The patent combines the blue laser diode and red LED into an anti-parallel configuration that shares a single driver channel. This merging allows the system to achieve enhanced red spectral content through the red LED without requiring a separate driver channel for the red source, thus avoiding the complexity of advanced multi-channel driver control while still achieving improved CRI.
3Adaptability or versatility
If special spectral light compositions are used to increase melanopic daylight efficacy ratio (MDER) factor, then the biological effects of natural light are improved, but the device complexity increases due to multi-channel drivers and wiring
Solution Approach 1:
The patent merges multiple lighting loads with different spectral characteristics into an anti-parallel configuration that can be controlled by a single driver channel. This allows the system to achieve special spectral light compositions for enhanced melanopic daylight efficacy ratio and biological effects without requiring the complex multi-channel driver wiring that would normally be needed to control multiple independent color channels.
4Adaptability or versatility
If a capacitor is placed in parallel to the lighting loads, then the current distribution becomes frequency dependent, but the impedance of capacitance reduces with frequency increase
Solution Approach 1:
The patent utilizes the frequency-dependent behavior of the parallel capacitor in conjunction with AC voltage from a parallel resonant converter. By operating at specific frequencies, the system can control current distribution between the capacitor and lighting loads. The periodic AC voltage allows the anti-parallel lighting loads to conduct during opposite half-cycles, with the capacitor providing reactive current that can be managed through frequency control.
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 simplified driver design, efficient current distribution, and flexible color control by adjusting frequency and duty cycle, reducing complexity and enabling a wider range of color temperatures and intensities.
Implementation Method 1
a parallel resonant converter comprising: an input node for receiving an input voltage; an output node; a half bridge comprising: a first switch coupled between the input node and a switching node; and a second switch coupled between the switching node and a return node; a controller adapted to provide a first control signal to the first switch and a second control signal to the second switch; and an inductor coupled between the switching node and the output node
Implementation Method 2
A capacitor is placed in parallel to the first and second lighting loads. The parallel resonant converter provides a current to the first and second load and the capacitor. The first and second switch are controlled by a controller, which provides a control signal to each respective switch. The control of the switches determines the amount of current that is provided to the load. Now that a capacitor is placed in parallel to the first and second lighting load, the current that flows through the first lighting loads has become frequency dependent.
Data Source
AI summary
The invention relates to a lighting system comprising a parallel resonant converter comprising an input node for receiving a bus voltage an output node a half bridge comprising a first switch coupled between the input node and a switching node and a second switch coupled between the switching node and a return node. The parallel resonant converter further comprises a controller adapted to provide a first control signal to the first switch and a second control signal to the second switch an inductor coupled between the switching node and the output node. The lighting system further comprises a load comprising a first load part, the first load part comprising a first lighting load a capacitor coupled in parallel with the first lighting load and a second lighting load coupled in anti-parallel with the first lighting load, wherein the load further comprises: a third lighting load and a fourth lighting load, coupled in anti-parallel with the third lighting load, wherein the third lighting load and the fourth lighting load are coupled in series with the first load part.