Time-of-Flight Sensor Using Phase Shift Clock Synchronization
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Solution Overview
Problem
Existing time-of-flight sensors face challenges with high power consumption and complexity due to the need for long pulses and ambient light compensation in distance measurement applications.
Innovation Solution
A sensor arrangement that periodically emits electromagnetic radiation pulses based on a first clock signal, with detected pulses separated into intervals and a phase difference determined using a second clock signal, allowing for reduced power consumption and complexity by generating an output signal indicative of time-of-flight based on the phase difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If long pulses of electromagnetic radiation are emitted to increase measurable distance, then the maximum measurable distance is improved, but power consumption increases
Solution Approach 1:
The system uses periodic emission of electromagnetic radiation pulses synchronized with a first clock signal, and periodic sampling of reflected radiation synchronized with a second clock signal. This periodic action allows the use of shorter pulses while maintaining accurate time-of-flight measurement capability, thereby reducing power consumption while preserving measurable distance capability.
Solution Approach 2:
The invention changes the timing parameters by introducing a phase difference between the emission clock signal and the detection clock signal. By adjusting the phase difference and using synchronized periodic sampling, the system achieves accurate distance measurement with shorter pulses, resolving the contradiction between pulse length and power consumption.
2Measurement precision
If ambient light compensation is implemented by measuring and subtracting ambient light signals, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The system converts the harmful effect of ambient light into a useful measurement mechanism. By using synchronous detection with a phase-shifted clock signal, the system naturally rejects ambient light through coherent detection of the modulated signal, eliminating the need for separate ambient light measurement and subtraction circuits.
Solution Approach 2:
The invention replaces the mechanical/software-based ambient light compensation method (measuring and subtracting ambient signals) with an optical/electrical synchronous detection method. The phase-shifted clock-based detection inherently filters out unmodulated ambient light, simplifying the overall system architecture.
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 reduces power consumption and complexity while maintaining the ability to determine maximum time-of-flight and distance without increasing pulse length, and inherently cancels ambient light effects, simplifying the sensor arrangement.
Implementation Method 1
a photonic demodulator configured to detect electromagnetic radiation during detection intervals
Data Source
AI summary
A sensor arrangement for determining time-of-flight comprises an emitter configured to periodically emit pulses of electromagnetic radiation depending on a first clock signal, a photonic demodulator configured to detect electromagnetic radiation during detection intervals comprising first and second intervals and a processing circuit. A timing of the detection intervals is defined by a second clock signal having a phase difference with respect to the first clock signal. The demodulator is configured to generate demodulator signals depending on energy of the radiation detected during at least one of the first intervals and at least one of the second intervals, respectively. The processing circuit is configured to adapt the phase difference based on the demodulator signals and to generate an output signal indicative of the time-of-flight based on the phase difference.