Optical Distance Sensor Using Phase-Corrected Amplitude Measurement
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Solution Overview
Problem
Existing optical distance measurement systems face challenges in accurately measuring distances in both near and far ranges, especially in gesture recognition applications, due to interference from extraneous light and the difficulty in determining the degree of reflection, which affects the precision of amplitude-based measurements and the noise-limited phase-based measurements.
Innovation Solution
A sensor system that divides the detection area into near and far ranges, using signal amplitude and propagation time information to determine object distance, with the phase signal used to correct amplitude measurements by eliminating the unknown reflection coefficient, and combining both signals for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If amplitude-based distance measurement is used, then measurement can be performed in the near range, but measurement precision deteriorates due to unknown reflection coefficient
Solution Approach 1:
The patent introduces phase information as an intermediary element that mediates between the amplitude measurement and the unknown reflection coefficient. By using phase data to calculate the reflection coefficient, the system creates a bridge that allows amplitude-based distance measurement to become accurate even in the near range where reflection effects are significant.
Solution Approach 2:
The patent changes the measurement parameter from relying solely on amplitude to using a combination of phase and amplitude information. By extracting the reflection coefficient from phase measurements and applying it to correct the amplitude-based distance calculation, the system transforms an inaccurate measurement into a precise one across all ranges.
2Measurement precision
If phase-based distance measurement is used, then measurement precision improves, but noise limits the effectiveness in the near range
Solution Approach 1:
The patent applies partial action by using phase information selectively - not for direct distance measurement in the near range where it is noise-limited, but for extracting the reflection coefficient that corrects the amplitude measurement. This partial use of phase data avoids the noise problem while still benefiting from its precision-correcting capability.
Solution Approach 2:
The patent converts the limitation of phase measurement (noise sensitivity in near range) into a benefit by using it solely for reflection coefficient extraction rather than direct distance measurement. The harmful noise effect is avoided while the useful phase information is still utilized to improve overall measurement accuracy.
3Ease of manufacture
If simple LED and photodiode systems are used, then costs are reduced, but measurement precision deteriorates due to extraneous light interference
Solution Approach 1:
The patent implements feedback by using the phase measurement to calculate the reflection coefficient, which then feeds back to correct the amplitude-based distance measurement. This feedback mechanism compensates for the lack of sophisticated interference rejection hardware, allowing simple LED-photodiode systems to achieve high precision by intelligently processing the measurement signals.
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 system provides robust and accurate distance measurements in both near and far ranges, reducing errors associated with reflection and noise, and enables reliable gesture recognition by effectively compensating for extraneous light interference.
Implementation Method 1
Due to the speed of light and the resulting short light propagation times in the close range, optical distance measurements are very difficult
Implementation Method 2
an object that is reflective and/or transmissive for electromagnetic radiation
Data Source
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AI summary
In a method for optically measuring the properties of at least one measurement path (I1, I2) between a transmitter (H) and a receiver (D), the receiver (D) receives an optical signal from a compensation transmitter (K) in addition to an optical signal from the transmitter (H). The signal of the transmitter (H) is reflected by an object (O) or is transmitted to the receiver (D) by means of said object in a different manner. The output signal (SO) of the receiver (D) is fed to a controller (CT), which changes the transmitter feed signal (S5) and/or compensation feed signal (S3) in accordance with a control algorithm. In the process, the controller (CT) determines two signals or values, which represent control parameters (S4a, S4φ) for magnitude and phase or magnitude and delay. In a stage downstream of the controller (CT), the presence and/or the distance (r) of an object (O) is determined from said two control parameters (S4a, S4φ) in dependence on at least one of said two parameters, either from both parameters or from one of the two parameters.