Canceling Voltage-Dependent Phase Error in iToF Sensors
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Solution Overview
Problem
Indirect time-of-flight (iToF) sensors face accuracy limitations due to voltage dependency, temperature variations, and manufacturing influences, making it challenging to set strict power supply voltage specifications and maintain accurate depth measurements.
Innovation Solution
An imaging device with a control unit that cancels voltage-dependent phase errors by determining and compensating for phase errors caused by power supply voltage and temperature variations using characteristic curves and polynomial models, allowing for accurate depth measurements regardless of voltage and temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage dependency compensation is not implemented, then the device complexity remains low, but the measurement precision deteriorates due to power supply voltage variations
Solution Approach 1:
The control unit pre-calculates voltage-dependent phase errors using stored characteristic curves that map power supply voltage to phase error values. By performing this compensation calculation in advance based on measured voltage values, the system eliminates the need for complex real-time hardware compensation circuits while maintaining high measurement precision.
Solution Approach 2:
Characteristic curves serve as an intermediary between the power supply voltage and the phase angle measurement. These pre-stored lookup tables translate voltage variations into corresponding phase error values, which are then subtracted from raw measurements to produce compensated depth values, simplifying the overall compensation architecture.
2Measurement precision
If strict power supply voltage specifications are enforced, then the measurement precision improves, but the adaptability deteriorates as the device becomes sensitive to voltage variations
Solution Approach 1:
The system dynamically adjusts the phase angle measurement by applying voltage-dependent compensation based on the actual power supply voltage. Instead of requiring the voltage to remain within strict specifications, the system adapts to any voltage level by calculating and subtracting the corresponding phase error from characteristic curves, thereby maintaining measurement accuracy across a wide voltage range.
Solution Approach 2:
The control unit continuously monitors the power supply voltage and uses this feedback to determine the appropriate phase error compensation. By measuring the actual voltage and referencing it against stored characteristic curves, the system automatically adjusts compensation levels to maintain accurate depth measurements despite voltage fluctuations.
3Measurement precision
If voltage monitoring and compensation calculations are performed, then the measurement precision improves, but the use of energy increases due to additional processing operations
Solution Approach 1:
Characteristic curves mapping voltage to phase error are pre-calculated and stored in memory during manufacturing or initial setup. This preliminary action eliminates the need for complex real-time calculations during operation, requiring only simple lookup and subtraction operations that consume minimal energy while maintaining high measurement precision.
Solution Approach 2:
The system performs only the essential compensation calculation by looking up pre-stored characteristic curve values and subtracting them from raw measurements. By avoiding full recalculation of compensation parameters and performing only the necessary arithmetic operations, the system achieves adequate precision improvement with minimal additional energy consumption.
Data Source
AI summary
An imaging device comprising a control unit configured to cancel a voltage dependent phase error of the imaging device caused by a power supply voltage dependency of a phase angle measured by the imaging device.