Time-of-Flight Sensor Histograms for Multi-Target Distance Detection
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Solution Overview
Problem
Existing time-of-flight measurement devices struggle to detect multiple targets effectively, often requiring complex setups with multiple components and lacking efficient methods for processing multiple objects in the field of view.
Innovation Solution
A semiconductor body integrated with a driver, multiple detectors, a time-to-digital converter arrangement, and a memory system, capable of generating and processing histograms to determine distances to multiple objects, integrated into a system-on-a-chip (SOC) configuration, utilizing avalanche diodes and narrow light pulses for precise distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple detectors and histograms are used to detect multiple targets, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent divides the detection task into multiple independent detectors, each responsible for detecting light from different directions or regions. Each detector generates its own histogram, allowing the system to resolve multiple targets by analyzing multiple histograms simultaneously. This segmentation enables multi-target detection while keeping each detector's processing relatively simple.
Solution Approach 2:
The patent introduces a histogram dimension to store time-of-flight data, transforming the detection problem from simple distance measurement to multi-dimensional data analysis. By accumulating photon arrival times in histograms and analyzing peaks in the histogram data, the system can distinguish multiple targets at different distances, effectively adding a temporal dimension to the detection capability.
2Measurement precision
If narrow light pulses are used for precise distance measurement, then measurement precision is improved, but detection difficulty increases
Solution Approach 1:
The patent continuously emits narrow light pulses and continuously accumulates photon arrival times in the histogram, rather than using single-shot measurements. This continuous accumulation of data over multiple pulses compensates for the low signal level from narrow pulses, maintaining measurement precision while reducing detection difficulty through statistical averaging.
Solution Approach 2:
The system performs preliminary accumulation of photon arrival times in the histogram before final distance calculation. By pre-processing the raw timing data and organizing it into histogram bins, the system simplifies the subsequent peak detection and distance calculation steps, making the overall measurement process more manageable despite using narrow pulses.
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
Enables accurate detection and processing of distances to multiple objects, simplifying the setup and improving accuracy in various conditions, including those with cover glass contamination, while reducing the need for factory calibration and enhancing autofocus capabilities in low-light environments.
Implementation Method 1
Each detector may comprise an avalanche diode or an avalanche diode array
Implementation Method 2
Each detector may comprise an avalanche diode or an avalanche diode array
Implementation Method 3
These devices send out a light pulse and measure the time it takes until the reflected light has reached the detector circuits of the device
Implementation Method 4
These devices send out a light pulse and measure the time it takes until the reflected light has reached the detector circuits of the device
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
A semiconductor body comprises a driver (DRV) for driving a light source (LS), at least two detectors (RD, D1 to D4) each comprising an avalanche diode (AD), a time-to-digital converter arrangement (CA, C1 to C4) coupled to outputs of the at least two detectors (RD, D1 to D4), a memory (ME, RM, M1 to M4) that is coupled to the time-to-digital converter arrangement (CA, C1 to C4) and is configured to store at least one histogram, and an evaluation unit (EV) coupled to the driver (DRV) and to the memory (ME, RM, M1 to M4).