Multi-Channel Distance-Measuring Module With External Signal Shifting
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Solution Overview
Problem
Existing multi-channel distance measuring modules, particularly those using integrated circuits, are limited by periodic or cyclic errors, parasitic effects, and inflexible clock frequencies, which degrade accuracy and increase power consumption.
Innovation Solution
A multi-channel distance measuring module with an external signal shifting unit and adaptive trigger timing system, utilizing a signal shifting unit to alter emission instants relative to the sampling clock, and a sensor-defined trigger system to reduce periodic errors and parasitic effects, while maintaining flexibility without significant power increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sampling clock frequency is increased to improve time resolution, then measurement precision improves, but power consumption increases
Solution Approach 1:
The patent implements dynamic clock frequency selection where the sampling clock frequency is adaptively adjusted based on measurement requirements. The system can switch between different clock frequencies (e.g., 100 MHz, 200 MHz, 400 MHz) to balance measurement precision needs against power consumption constraints, allowing high precision only when necessary
Solution Approach 2:
The system changes the sampling clock frequency parameter dynamically based on operational conditions. By varying this critical parameter, the system optimizes the trade-off between time resolution (measurement precision) and power consumption, selecting higher frequencies only when measurement accuracy demands it
2Measurement precision
If the sampling clock frequency is increased to improve time resolution, then measurement precision improves, but periodic errors increase
Solution Approach 1:
The patent employs multiple sampling clock frequencies with different periods. By selecting from a set of periodic sampling rates (100 MHz, 200 MHz, 400 MHz), the system can avoid resonant frequencies that cause periodic errors while maintaining adequate time resolution for accurate distance measurement
Solution Approach 2:
The system uses a composite approach by combining multiple sampling clock frequencies rather than relying on a single fixed frequency. This composite frequency strategy allows the system to mitigate periodic errors that occur at specific frequencies while maintaining overall measurement precision through selective frequency usage
3Ease of manufacture
If integrated circuits are used to reduce device complexity, then ease of manufacture improves, but susceptibility to parasitic effects increases
Solution Approach 1:
The patent introduces an external signal shifting unit as an intermediary component between the integrated circuit and the sampling clock source. This external unit isolates the sensitive integrated circuit from parasitic effects in the clock signal, allowing the use of integrated circuits while mitigating their susceptibility to harmful electromagnetic interference
Solution Approach 2:
The system segments the distance measuring module into separate functional units: an integrated circuit for core processing and an external signal shifting unit for clock signal conditioning. This segmentation allows the integrated circuit to benefit from manufacturing advantages while the external unit handles parasitic effect mitigation
4Ease of operation
If fixed trigger timing is used to simplify operation, then ease of operation improves, but measurement accuracy deteriorates due to periodic errors
Solution Approach 1:
The patent implements dynamic trigger timing adjustment where the trigger instant is adaptively shifted relative to the sampling clock based on measured periodic errors. The system automatically adjusts the trigger timing to optimize measurement accuracy while maintaining simple operation through automated adjustment rather than manual calibration
Solution Approach 2:
The system uses feedback from periodic error measurements to automatically adjust trigger timing. The measured periodic errors feed back into the trigger timing control, which then adjusts the trigger instant to minimize measurement errors, creating a self-correcting system that maintains high accuracy without complex manual operation
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 solution effectively reduces periodic errors and susceptibility to parasitic effects, enhancing accuracy and flexibility in distance measurements while minimizing power consumption.
Implementation Method 1
The distance is measured based on a parameter associated with the time-of-flight of a measurement signal emitted by the distance measuring module and returning from the environment
Implementation Method 2
Each of the SPAD elements is designed for the purpose of being able to detect an arrival time of individual photons (or individual photon packages) correctly
Data Source
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Figure 5~6
AI summary
The invention relates to a multi-channel distance measuring module (1, 1', 1", 1'", 1"") for providing scanning of an environment, e.g. for use in a laser tracker, tachymeter, scanning instrument, profiler, or surveillance instrument. By way of example, the multiple channels provide for generating a 3D image. The distance measuring module (1, 1', 1", 1 ‴, 1"") comprises an emitter (2) for emitting emission signals (3) and a sensor unit (4) embodied as integrated circuit, which comprises a multi-channel receiver (5) with a detection surface comprising multiple detection elements (26), e.g. SPAD elements, arranged as a matrix structure on a chip, and a trigger unit (6) configured to generate a sensor output trigger signal (7) that provides trigger times (10) defined by the sensor unit (4). Each of the multiple channels of the receiver (5) is provided by a macro-pixel (25) formed by a subset of the detection elements (26) associated to the detection channel. The distance measuring module (1, 1', 1", 1"', 1"") further comprises a signal shifting unit (9) external to the sensor unit (4) for altering the time positioning of actual emission instants (11) by the emitter (2) relative to a sampling clock (8) of the sensor unit (4). The emission instants (11) of the emission signals (3) are based on the sensor output trigger signal (7), wherein each of the emission instants (11) corresponds to a corresponding one of sensor-defined trigger times (10) given by the sensor output trigger signal (7) but the signal shifting unit (9) introduces an offset between a relative temporal positioning of a respective emission instant (11) to the sampling clock (8) and a relative temporal positioning of its corresponding sensor-defined trigger time (10) to the sampling clock (8).