Optical Sensor Initial Phase Convergence for Distance Measurement
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Solution Overview
Problem
Existing distance measurement methods using single photon avalanche diodes require long measurement times to achieve accurate results, especially when the sensing target is remote or reflectance is low, leading to reduced accuracy due to low pulse generation ratios and phase convergence issues.
Innovation Solution
An optical sensor configuration that includes a first and second photon count-type light-receiving unit, a time difference extraction circuit with DLL circuits, and an initial configuration circuit that determines the initial phase value by counting pulse outputs across divided clock cycles to advance convergence time, reducing measurement time while maintaining accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single photon avalanche diode is used to obtain pulse outputs for distance measurement, then measurement accuracy can be improved, but measurement time increases significantly when the sensing target is remote or reflectance is low
Solution Approach 1:
The patent applies preliminary action by performing an initial phase convergence operation before the actual distance measurement. The system first acquires pulse outputs and determines an initial phase value that brings the DLL circuit close to its convergence point. This preliminary positioning reduces the time required for phase convergence during subsequent measurements, thereby reducing overall measurement time while maintaining accuracy.
2Measurement precision
If a long measurement time is used to obtain a large number of pulses from the single photon avalanche diode, then phase convergence and measurement accuracy are improved, but productivity decreases
Solution Approach 1:
The system performs preliminary pulse acquisition and initial phase determination before actual measurement. By acquiring a sufficient number of pulses in advance to establish an accurate initial phase value, the system ensures that the DLL circuit starts from an optimized position, reducing the time needed for phase convergence during production measurements and thereby improving productivity.
Solution Approach 2:
The patent implements periodic action through cyclic measurement operations. The system alternates between initial phase determination phases and actual measurement phases. During initial phase determination, the system accumulates pulse outputs to establish phase information, then uses this information to accelerate subsequent measurements, creating an efficient periodic cycle that improves overall productivity.
3Productivity
If the measurement time is shortened to improve productivity, then measurement speed increases, but phase convergence cannot be achieved and accuracy decreases
Solution Approach 1:
The patent ensures that sufficient preliminary pulse acquisition is performed to establish an accurate initial phase value before shortening the actual measurement time. This preliminary action guarantees that the DLL circuit starts from an optimized phase position, allowing short measurement times to achieve both high productivity and maintained accuracy.
Solution Approach 2:
The system uses feedback from the initial phase determination process to adjust and optimize subsequent measurements. The phase information obtained during preliminary pulse acquisition is fed back to set the initial phase value for the DLL circuit, ensuring that even shortened measurements maintain accuracy by starting from an optimized position based on previous measurements.
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 configuration enables faster and more accurate distance measurements by optimizing the initial phase convergence of the DLL circuit, reducing measurement time without compromising accuracy, even for distant or low-reflectance targets.
Implementation Method 1
an avalanche photodiode using an avalanche amplification effect of a photodiode has been adopted as a light-receiving element for detecting faint light at high speed
Implementation Method 2
the avalanche photodiode in the Geiger mode causes an avalanche phenomenon even with incidence of a single photon, and thus, a large output current is obtained
Implementation Method 3
reflected light from a sensing target
Data Source
AI summary
An optical sensor configured to reduce a measurement time while the accuracy of the optical sensor is maintained is realized. An initial configuration circuit (19) includes a counter configured to perform counting of the number of pulse outputs from a first light-receiving unit (11) in first to nth regions obtained by dividing each cycle of a reference clock into n equal parts, determines, among the first to nth regions, a region in which a counter value is largest, and the initial configuration circuit causes a first DLL circuit (17) to perform a converging operation to the region determined.