Analog Laser Driver for iToF Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Time-of-flight systems face limitations in controlling the light emitted by laser drivers, as they typically rely on digital control signals that only manage the on/off states of the laser, lacking control over the intensity and amplitude of the laser drive current.
Innovation Solution
The introduction of an analog laser control signal generated by the imager, which is received by the laser driver to produce an analog laser drive current, allowing for adjustable intensity and improved control over the laser output, including the use of high-side laser drivers and current mirrors for efficient current generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If digital control signals are used to control the laser driver, then the system is simple to implement, but the control over laser intensity and amplitude is limited
Solution Approach 1:
The patent changes the control signal from digital (binary on/off) to analog (continuous voltage), enabling continuous adjustment of laser drive current amplitude. This allows precise control over laser intensity by varying the voltage level, directly resolving the limitation of digital control while maintaining system simplicity through direct voltage-to-current conversion.
Solution Approach 2:
The patent introduces an analog laser control signal as an intermediary between the imager and laser driver. This analog signal serves as a mediator that carries continuous control information about desired laser intensity, enabling smooth transitions and precise amplitude control without requiring complex digital processing or additional control circuitry.
2Measurement precision
If analog laser control signal is used, then the precision and control over laser output is improved, but the system complexity increases
Solution Approach 1:
The patent changes the control signal parameter from digital (discrete states) to analog (continuous voltage), enabling precise control of laser drive current amplitude. This continuous parameter control directly improves distance measurement accuracy in ToF systems by allowing fine-adjustment of laser intensity for optimized signal-to-noise ratio, while the implementation remains relatively simple through direct voltage-to-current conversion circuits.
3Measurement precision
If higher laser drive current is used to improve signal strength, then the measurement accuracy improves, but thermal management becomes more difficult
Solution Approach 1:
The patent implements dynamic control of laser drive current through analog voltage signaling, allowing the system to adjust current levels in real-time based on measurement requirements. This enables using higher currents only when needed for improved signal detection, while maintaining lower currents during normal operation, thus improving measurement accuracy when required without sustaining excessive thermal load continuously.
Solution Approach 2:
The patent uses analog voltage control to dynamically change the laser drive current parameter. By varying the control voltage amplitude, the system can optimize laser intensity for each measurement scenario, achieving high signal strength and improved accuracy only when necessary, thereby reducing average thermal load and improving thermal management compared to fixed high-current operation.
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
This approach enables greater precision and control over the laser output, enhancing the accuracy of distance measurements in time-of-flight systems by allowing for calibrated adjustments in laser intensity, improving thermal management, and reducing parasitic inductance and resistance.
Implementation Method 1
generate an analog laser drive current having an amplitude that is dependent on an amplitude of the analog laser control signal; and output the analog laser drive current to a laser for driving the laser to emit light
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The present disclosure provides an improved indirect time-of-flight (iToF) system. The iToF system includes an imager and a laser driver system. The laser driver system receives an analog laser control signal from the imager, generating an analog laser driver current based on the analog laser control signal. The analog laser driver current is generated such that any change in an amplitude of the analog laser control signal causes a change in an amplitude of the analog laser drive current. Further, the present disclosure provides improved imagers and laser driver systems for use in an indirect time-of-flight system. An indirect time-of-flight system including a high-side multiplicative push-pull current mirror is also provided.