Proximity Detection Device With Variable Optical Pulse Durations
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Solution Overview
Problem
Proximity detection devices using SPAD arrays face challenges in accurately determining the timing of return pulses due to high ambient light, reflective targets, and noise, leading to congestion and imprecision in range estimation.
Innovation Solution
A proximity detection device employing a range estimation circuit with a pulse transmission circuit that transmits optical pulses of varying durations, where a second pulse is at least 50% longer than the first, and a readout circuit that samples signals at regular intervals, storing samples in a histogram memory to accumulate data across detection periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single pulse duration is used in SPAD array-based proximity detection, then the device complexity is reduced, but the measurement precision deteriorates under varying ambient light conditions and target reflectivity
Solution Approach 1:
The system dynamically adjusts the optical pulse duration based on detection conditions. The pulse transmission circuit is configured to transmit a first optical pulse with a first pulse duration and a second optical pulse with a second pulse duration, where the second pulse duration is at least 50% longer than the first. This dynamic adaptation allows the system to optimize timing accuracy for different ambient light conditions and target characteristics without requiring multiple fixed-configuration devices.
2Adaptability or versatility
If multiple optical pulses with different durations are transmitted, then the measurement precision and adaptability are improved, but the productivity decreases due to extended detection period
Solution Approach 1:
The system employs periodic transmission of optical pulses with different durations within a structured detection period. The pulse transmission circuit transmits pulses in a repeating pattern where the second pulse (longer duration) and first pulse (shorter duration) are periodically alternated. This periodic action allows the system to maintain adaptability across varying conditions while ensuring that detection operations can be repeated at regular intervals, balancing versatility with operational throughput.
3Reliability
If longer optical pulses are used, then the signal-to-noise ratio is improved, but the crosstalk interference increases
Solution Approach 1:
The system applies different pulse durations tailored to specific detection needs rather than using a uniform pulse width. The pulse transmission circuit is configured to transmit a first optical pulse with a first pulse duration and a second optical pulse with a second pulse duration, where the second pulse duration is at least 50% longer than the first. This local differentiation allows longer pulses to be used where higher signal-to-noise ratio is needed while shorter pulses are used where crosstalk is a concern, optimizing performance for different spatial and temporal regions of the detection scene.
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 precise detection of objects at both short and long ranges with reduced crosstalk interference and improved signal-to-noise ratio, effectively addressing the limitations of existing SPAD array-based systems.
Implementation Method 1
a pulse transmission circuit configured to transmit into the scene a first optical pulse having a first pulse duration and a second optical pulse having a second pulse duration
Implementation Method 2
one or more photodetectors configured to generate events in response to one or more optical pulses received from the object of the scene against which the optical pulses reflect
Implementation Method 3
a readout circuit configured to sample one or more output signals from the one or more photodetectors at regular intervals throughout a detection period
Data Source
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AI summary
The present disclosure relates to a proximity detection device comprising: one or more photodetectors (110); a readout circuit (115) configured to sample one or more output signals from the one or more photodetectors at regular intervals throughout a detection period; and a pulse transmission circuit (116, 118, 102) configured to transmit into the scene a first optical pulse having a first pulse duration and a second optical pulse having a second pulse duration, the second pulse duration being at least 50 percent longer than the first pulse duration.