Optoelectronic Module Dual-Modulation Distance Measurement
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Solution Overview
Problem
Current optoelectronic modules for distance measurements, such as time-of-flight sensors, face challenges in accurately determining object distance due to spurious reflections from elements like smudges on the host device's cover glass, which can compromise the accuracy of proximity data and hinder the execution of supplemental measurements like heart rate or blood oxygen monitoring.
Innovation Solution
The optoelectronic module employs a dual-modulation frequency approach to differentiate between reflections from the object and spurious reflections, using demodulation pixels and processing circuitry to subtract out the spurious components, allowing for precise distance determination and triggering of supplemental measurements based on object recognition protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-of-flight sensors use phase-measurement technique to detect distance, then distance measurement capability is achieved, but spurious reflections from smudges on cover glass compromise measurement accuracy
Solution Approach 1:
The patent segments the reflected light signal into multiple frequency components using dual-modulation frequencies. By modulating the light source at two different frequencies and analyzing the reflected signals separately, the system can distinguish between valid object reflections and spurious reflections from smudges, thereby resolving the measurement accuracy problem caused by spurious reflections.
Solution Approach 2:
The patent changes the modulation frequency parameter of the light source to differentiate between valid and spurious reflections. By using two distinct modulation frequencies and analyzing the phase and amplitude characteristics of the reflected signals at each frequency, the system can identify and eliminate spurious reflection components, thus improving distance measurement accuracy.
2Adaptability or versatility
If the module performs supplemental measurements like heart rate monitoring, then additional functionality is added, but the presence of spurious reflections reduces reliability of these measurements
Solution Approach 1:
The patent applies signal segmentation by separating the reflected light signal into multiple frequency components. This allows the system to isolate and remove spurious reflection components before performing supplemental measurements, thereby maintaining high reliability for heart rate and blood oxygen monitoring functions.
Solution Approach 2:
The patent uses feedback mechanisms where the system continuously monitors the reflected light signals, identifies spurious reflection components based on their characteristic phase and amplitude relationships at different modulation frequencies, and dynamically adjusts the measurement process to compensate for these interference signals, ensuring reliable supplemental measurements.
3Device complexity
If the system uses single modulation frequency for distance measurement, then device complexity is reduced, but inability to distinguish spurious reflections limits measurement accuracy
Solution Approach 1:
The patent employs periodic modulation of the light source at two distinct frequencies. This periodic action creates distinguishable signal patterns in the reflected light that allow the system to differentiate between valid object reflections and spurious reflections from smudges, achieving high measurement accuracy without requiring overly complex hardware.
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 method enhances the accuracy of distance measurements by compensating for spurious reflections and enables the reliable execution of supplemental biometric measurements, such as heart rate and blood oxygen monitoring, by distinguishing between valid object signals and spurious reflections.
Implementation Method 1
detect radiation of the first wavelength reflected from the object
Implementation Method 2
the photo-generated electrons are demodulated in the sensor
Implementation Method 3
emitting light from the module toward an object outside the module at a first modulation frequency and at a second modulation frequency
Implementation Method 4
subtracting out a component in signals detected by the demodulation pixels, wherein the component is caused by a reflection from an element in or on the optoelectronic module
Data Source
AI summary
An optoelectronic module includes a first light emitter operable to emit radiation at a first wavelength toward an object outside the module. The module also includes demodulation pixels operable to detect radiation of the first wavelength reflected from the object. One or more processors are operable to determine a distance to the object based on the radiation detected by the demodulation pixels. The module is further operable to perform a supplemental measurement other than distance.