TOF Distance Measurement Interference Detection
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Solution Overview
Problem
Existing time-of-flight (TOF) distance measurement technologies fail to reliably detect and mitigate interference from other distance measuring apparatuses, leading to incorrect distance calculations and signal saturation issues.
Innovation Solution
A distance measuring apparatus using a TOF method with a light source, light receiver, and signal processor, where multiple pixels with different read control signals are used to dynamically detect interference by comparing signal levels and accumulation periods, allowing for accurate distance calculation even in the presence of interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single pixel with fixed read gate timing is used, then the device complexity is low, but interference from other distance measuring apparatus cannot be detected
Solution Approach 1:
The pixel array is segmented into multiple pixel groups, where each group has pixels with different read gate timing configurations. This segmentation allows the system to detect interference by comparing signals from pixels with different accumulation periods without requiring every pixel to have complex multi-timing capabilities, thus improving interference detection while controlling device complexity.
Solution Approach 2:
The read gate timing is made dynamic rather than fixed. Pixels can switch between different read gate timing modes (first timing for normal measurement, second timing for interference detection). This dynamic capability enables the system to adapt to interference conditions while maintaining reasonable device complexity through controlled switching.
2Reliability
If multiple pixels with different read control signals are used to detect interference, then interference detection reliability improves, but the device complexity increases
Solution Approach 1:
The system uses periodic switching between different read control signal patterns. During normal operation, a first read control signal pattern is used; when interference is detected, a second read control signal pattern is activated. This periodic action allows reliable interference detection through comparison while managing control complexity through systematic signal switching rather than continuous complex control.
Solution Approach 2:
The system implements feedback by comparing distance measurement results from pixels with different read gate timings. When a discrepancy exceeds a threshold, the system determines interference is present and adjusts subsequent measurements accordingly. This feedback mechanism improves interference detection reliability while controlling complexity through algorithmic processing rather than hardware complexity.
3Adaptability or versatility
If light accumulation period is fixed, then the measurement process is simple, but the dynamic range of distance measurement is limited
Solution Approach 1:
The light accumulation period is made dynamic by switching between a first accumulation period (for normal distance measurement) and a second accumulation period (for interference detection and extended range measurement). This dynamic adjustment expands the measurable distance range while controlling exposure control complexity through systematic period switching rather than continuous adjustment.
Solution Approach 2:
The system changes the accumulation period parameter based on detection needs. By varying this key parameter between two distinct values (first and second accumulation periods), the system achieves extended dynamic range for distance measurement while managing complexity through discrete parameter changes rather than continuous variation.
4Measurement precision
If interference detection is not implemented, then the device complexity remains low, but incorrect distance information is obtained when interference occurs
Solution Approach 1:
The measurement system is segmented into multiple pixel groups with different read gate timings, allowing interference detection through comparative measurement. This segmentation approach improves distance measurement accuracy by enabling interference identification while controlling system complexity through modular pixel group design rather than system-wide complexity.
Solution Approach 2:
Pixels with different read gate timings act as intermediaries for interference detection. By comparing measurements from these intermediary pixels, the system can identify interference conditions and adjust subsequent measurements accordingly, thereby improving distance measurement accuracy while managing complexity through the intermediary comparison mechanism.
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
The apparatus effectively detects and reduces interference, enabling reliable distance measurements and increasing the dynamic range of distance measurement data by using pixels with different charge accumulation periods.
Implementation Method 1
each of the plurality of pixels includes: a photoelectric converter which converts the incident light into electric charge
Implementation Method 2
an accumulator which accumulates the electric charge
Implementation Method 3
a light source which emits light
Data Source
AI summary
A distance measuring apparatus includes a light source, a light source controller, a light receiver including pixels arranged two-dimensionally, an exposure controller, and a signal processor. The light receiver outputs, to the signal processor, a signal corresponding to the amount of electric charge accumulated in the accumulator. The signal processor determines that the interference is present when at least one of (i) a ratio between signal levels of the same pixel included in the pixels, the signal levels representing respective amounts of electric charge in respective exposure periods and (ii) a ratio between signal levels of the first and second pixels exceeds a predetermined threshold with respect to a determination criterion that is based on a difference between a period in which a read gate of the first pixel is open and a period in which a read gate of the second pixel is open.