Time-of-Flight Arrangement Without Optical Reference Path
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Solution Overview
Problem
Conventional time-of-flight measurement systems require an optical reference path and barrier to achieve high precision, leading to complex and costly package designs due to the need for a separate reference sensor, which increases package size, complexity, and power consumption.
Innovation Solution
A time-of-flight arrangement that operates without an optical reference path, using an electrical calibration path to determine delay information during a calibration phase, allowing for accurate time-of-flight measurements without the need for a reference sensor, thereby simplifying the package design and reducing complexity and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical reference path and optical barrier are used to achieve high measurement precision, then measurement accuracy is improved, but package size and complexity increase
Solution Approach 1:
The patent extracts and removes the optical reference path and optical barrier from the system. Instead of using a separate reference sensor and optical barrier to cancel systematic errors, the invention uses a single photodiode circuit where the driver signal is directly coupled to the photodiode input, eliminating the need for complex optical reference paths while maintaining measurement accuracy through electrical delay measurement
Solution Approach 2:
The patent merges the reference signal path and measurement signal path into a single integrated circuit path. The driver signal is electrically coupled to both the photodiode input (for reference timing) and the laser trigger, eliminating the need for separate reference sensors and optical barriers. This consolidation reduces package complexity while preserving the ability to measure and cancel systematic delays
2Measurement precision
If a separate reference sensor is used to cancel systematic errors, then measurement accuracy is improved, but package size increases
Solution Approach 1:
The patent merges the reference sensing function into the main photodiode circuit by electrically coupling the driver signal to the photodiode input. This eliminates the need for a separate reference sensor array, reducing package area while maintaining the ability to measure systematic delays for cancellation in the time-of-flight calculation
3Reliability
If an optical barrier is implemented to prevent crosstalk detection, then measurement reliability is improved, but manufacturing complexity and costs increase
Solution Approach 1:
The patent removes the optical barrier component from the system. Instead of using an optical barrier to physically block crosstalk, the invention uses electrical coupling and timing differentiation to distinguish the reference signal from actual reflected light signals, simplifying manufacturing while maintaining reliability
Solution Approach 2:
The patent replaces the mechanical/optical barrier system with an electrical signal processing approach. The driver signal is electrically coupled to the photodiode input, and the system uses timing information and signal processing to prevent crosstalk detection, eliminating the need for physical optical barriers and simplifying manufacturing
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 package size, complexity, and costs while maintaining high measurement accuracy, as the electrical calibration path eliminates the need for a separate reference sensor, allowing the laser and sensor die to be in separate cavities, resulting in improved reliability and quality.
Implementation Method 1
The photodiode circuit often comprises an avalanche photodiode such as a single photon avalanche photodiode, abbreviated as SPAD
Implementation Method 2
A time-of-flight arrangement sends out a light pulse and measures the time it takes until a reflected light reaches a photodiode circuit
Data Source
AI summary
A time-of-flight arrangement (10) comprises a laser (15), a laser driver (12), a clock generator (11) that is coupled to the laser (15) via the laser driver (12), a photodiode circuit (50) and a time-to-digital converter (14). The photodiode circuit (50) comprises an avalanche photodiode (51), a quenching circuit (52), a diode node (53) and a readout circuit (54). The quenching circuit (52) is coupled via the diode node (53) to the avalanche photodiode (51). An input of the readout circuit (54) is connected to the diode node (53). At least one of the clock generator (11) and the readout circuit (54) is coupled on its output side to the input side of the time-to-digital converter (14).