Laser Diode Driver Using Lookup Table Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light source driving devices for semiconductor light sources, such as laser diodes, face issues with rapid output rise and high circuit complexity due to feedback control mechanisms, leading to delayed laser output and increased power consumption.
Innovation Solution
A light source driving device with a variable DC power supply and a current control system that uses pre-stored characteristic data to maintain a constant inter-terminal voltage, allowing for rapid current rise and reduced power consumption by controlling the output voltage based on current-voltage and voltage drop characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If feedback control mechanism is used to control current driving element, then output voltage can be adjusted, but circuit complexity increases and response speed decreases
Solution Approach 1:
The patent pre-calculates and stores optimal voltage values in a lookup table based on current commands. When a current command is received, the corresponding voltage is directly retrieved without real-time calculation or feedback control, eliminating complex control circuits while maintaining accurate voltage adjustment capability.
Solution Approach 2:
The patent replaces the feedback control mechanism (electrical control system) with a direct lookup approach using stored characteristic data. This substitution eliminates the need for complex feedback circuits, sensors, and real-time computational hardware, significantly simplifying the circuit while preserving voltage adjustment functionality.
2Ease of operation
If feedback control mechanism is used to control current driving element, then output voltage can be adjusted, but response speed decreases
Solution Approach 1:
The patent pre-calculates and stores optimal voltage values in a lookup table based on current commands. When a current command is received, the corresponding voltage is directly retrieved without real-time calculation or feedback control, eliminating complex control circuits while maintaining accurate voltage adjustment capability.
Solution Approach 2:
The patent skips the time-consuming feedback control loop and real-time voltage calculation steps by directly retrieving pre-computed voltage values from storage. This allows the system to rapidly respond to current commands without waiting for feedback signals or performing complex real-time computations.
3Device complexity
If constant voltage is applied to current driving element, then circuit is simple, but power consumption increases and temperature rise occurs
Solution Approach 1:
The patent dynamically adjusts the voltage applied to the current driving element based on the required current command. Instead of applying constant voltage, the system retrieves optimal voltage values from stored characteristic data that correspond to different current levels, enabling voltage to vary dynamically with operating conditions.
Solution Approach 2:
The patent changes the voltage parameter based on the current command by retrieving pre-calculated voltage values from storage. This allows the voltage to be optimized for each operating point, reducing power consumption and temperature rise while maintaining circuit simplicity through direct lookup rather than complex real-time control.
4Measurement precision
If feedback control is implemented, then voltage can be precisely controlled, but circuit complexity and power consumption increase
Solution Approach 1:
The patent pre-calculates and stores optimal voltage values in a lookup table based on current commands. When a current command is received, the corresponding voltage is directly retrieved without real-time calculation or feedback control, eliminating complex control circuits while maintaining accurate voltage adjustment capability.
Solution Approach 2:
The patent uses stored characteristic data that represents the ideal voltage-current relationship. Instead of implementing complex feedback control hardware, the system copies pre-determined voltage values from storage that have been calculated to achieve precise voltage control, thereby maintaining precision while avoiding circuit complexity.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A laser diode driving device (1) of the present invention includes: a variable DC power supply (3) for outputting a voltage for driving laser diodes (LD 1 to LDn); a current driving element (4) for causing a current If to flow; a current control section (5) for controlling (i) turning on and off of the current driving element (4) and (ii) the amount of the current If; and a power supply control section (7) for controlling an output voltage of the variable DC power supply (3). The power supply control section (7) controls, on the basis of If-Vf characteristic data (D2), voltage drop characteristic data (D3), and Vds setting data (D4) all stored in a memory section (8), the output voltage of the variable DC power supply (3) so that the current driving element (4) has a constant inter-terminal voltage regardless of the amount of the current If.