Laser Diode Shunt Circuit for Controlled Startup Voltage
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Solution Overview
Problem
Semiconductor laser diodes in lighting applications are susceptible to damage from electrical surges, overheating, and voltage fluctuations, particularly when operated in high-frequency environments, leading to Catastrophic Optical Damage (COD) and making it challenging to control individual laser diodes in bundled configurations.
Innovation Solution
A lighting circuit with a current driver circuit, series connection of laser diodes, and a current shunt circuit in parallel with each diode, controlled to manage the rate of change of voltage during startup, reducing the risk of damage and enabling synchronized lasing across diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple laser diodes are connected in series in a bundled configuration, then the system can achieve high light flux output, but individual laser diodes cannot be controlled or protected independently and voltage division becomes uncontrollable
Solution Approach 1:
The patent divides the bundled laser diode system into individually controllable segments by providing separate control circuits for each laser diode. This allows independent control and protection of each diode while maintaining series connection for high power output, resolving the contradiction between achieving high light flux and enabling individual diode control.
2Productivity
If laser diodes are operated at high frequencies near nominal power, then brightness and efficiency are maximized, but the devices become highly susceptible to surge damage and thermal runaway
Solution Approach 1:
The patent implements protection circuits that are activated before surge damage can occur. These circuits include over-temperature protection, over-current protection, and ESD protection that preemptively prevent damage by detecting abnormal conditions and shutting down or limiting current before catastrophic failure occurs, allowing the system to operate at high frequencies near nominal power safely.
Solution Approach 2:
The patent employs feedback mechanisms that continuously monitor temperature, current, and voltage parameters of each laser diode. When parameters approach dangerous thresholds, the feedback control adjusts operating conditions in real-time to prevent surge damage and thermal runaway, enabling sustained high-frequency operation at maximum efficiency.
3Stability of the object's composition
If binning procedures are used to match laser diode voltage thresholds, then voltage division stability improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the control parameter from passive voltage threshold matching (binning) to active real-time monitoring and adjustment. By using individual control circuits that can detect and respond to actual operating conditions of each laser diode, the system achieves stable voltage division without requiring precise manufacturing binning, thereby reducing manufacturing complexity while maintaining stability.
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 reduces the risk of crystal damage, ensures uniform voltage distribution, and allows for efficient operation of laser diode arrays, enabling synchronized start-up and reducing the need for current binning, while maintaining optimal efficiency and preventing voltage jumps.
Implementation Method 1
A respective current shunt circuit in parallel with each laser diode for diverting a shunt current away from the respective laser diode
Implementation Method 2
Semiconductor laser light sources are of increasing interest for lighting applications
Implementation Method 3
They typically employ a blue laser diode combined with a phosphor converter adding yellow components to the blue laser light resulting in a white light
Implementation Method 4
They typically employ a blue laser diode combined with a phosphor converter adding yellow components to the blue laser light
Implementation Method 5
when lasing increases, the increase in photons leads to heating of the crystal in the area of the mirroring facet
Data Source
AI summary
A lighting circuit comprises a current driver circuit and a series connection of at least two laser diodes, supplied with current from the current driver circuit. A current shunt circuit is in parallel with each laser diode for diverting a shunt current away from the respective laser diode. The level of the shunt currents is controlled during a start-up period of time of the current driver circuit in order to control the rate of change of voltage across selected laser diodes during said start-up period of time.