Optoelectronic Proximity Sensing With Asymmetric Field Overlap
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Solution Overview
Problem
Optoelectronic proximity sensors struggle to accurately measure proximity independent of object surface reflectivity, particularly for varying skin pigmentation of body parts like fingers, hands, or ears.
Innovation Solution
The use of an asymmetric field overlap configuration in optoelectronic devices, comprising multiple light-emitting and light-sensitive assemblies with distinct angles and pitches, allows for independent measurement of proximity by normalizing signal ratios to determine object position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optoelectronic proximity sensors use a single light-emitting assembly and a light-sensitive assembly, then the device structure is simple, but the proximity measurement is affected by object surface reflectivity
Solution Approach 1:
The single light-emitting assembly is divided into multiple light-emitting assemblies (first, second, third, etc.) with different emission angles. Each assembly illuminates the object from a different direction, and the light-sensitive assembly receives reflected light from each direction separately. This segmentation allows the system to measure proximity while compensating for surface reflectivity variations by comparing signals from multiple illumination angles.
Solution Approach 2:
The patent employs asymmetric field overlap where the light-sensitive assembly has a field-of-view that overlaps differently with the emission fields of multiple light-emitting assemblies. Specifically, the first light-emitting assembly emits light within a first field-of-illumination, the second light-emitting assembly emits light within a second field-of-illumination, and the light-sensitive assembly collects light from both directions within a single field-of-view. This asymmetric configuration enables the system to distinguish between changes in proximity and changes in surface reflectivity, thereby improving measurement accuracy.
2Reliability
If optoelectronic proximity sensors use asymmetric field overlap configuration, then proximity measurement becomes independent of object surface reflectivity, but the device complexity increases
Solution Approach 1:
The system segments the illumination function into multiple light-emitting assemblies positioned at different locations and orientations. Each assembly contributes to illuminating the object from a unique angle, creating distinct field-of-illumination zones. The light-sensitive assembly segments the detection function by selectively receiving light from different directions within its field-of-view, enabling independent measurement of proximity while compensating for surface reflectivity variations.
Solution Approach 2:
The asymmetric field overlap configuration is implemented by positioning the light-sensitive assembly such that its field-of-view overlaps with the emission fields of multiple light-emitting assemblies in an asymmetric manner. The first light-emitting assembly's field-of-illumination and the second light-emitting assembly's field-of-illumination overlap with the light-sensitive assembly's field-of-view differently, creating an asymmetric geometric relationship. This asymmetry ensures that the ratio of received light signals depends on proximity rather than surface reflectivity, thereby improving reliability.
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
Enables accurate proximity measurement irrespective of object surface reflectivity, utilizing asymmetric field overlap to normalize signal ratios and account for invariant reflectivity across the object's surface.
Implementation Method 1
collect light emitted by the first light-emitting assembly reflected from the object
Implementation Method 2
convert light emitted by the first light-emitting assembly reflected from the object into a first signal
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An optoelectronic device has an asymmetric field overlap and is operable to measure proximity independently of object surface reflectivity. In some instances, the optoelectronic device includes a plurality of light-emitting assemblies and a light-sensitive assembly. In some instances, the optoelectronic devices include a plurality of light-sensitive assemblies and a light-emitting assembly. An asymmetric field overlap is attained in various implementations via various field-of-view axis, field-of-view angle, field-of-illumination axis, field-of-illumination angle, optical element and/or pitch configurations.