Optical Angle Sensor with Asymmetric Target for Magnetic Immunity

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Solution Overview

Problem

Conventional angle sensors, particularly inductive and optical types, face issues with accuracy due to external magnetic interference and poor sensing precision, respectively.

Innovation Solution

An angle sensing device comprising a base, a rotation shaft with a detected target featuring distinct radial positions, and a proximity sensor that emits light to detect reflected light and generate measurement data, utilizing a processing unit for accurate angle determination, which is enhanced by neural network learning for correction parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If inductive angle sensor is used, then magnetic field sensing capability is provided, but external magnetic interference affects feedback control accuracy

Engineering Contradiction:

Improvefeedback control accuracyVSAvoidexternal magnetic interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the inductive angle sensor (which relies on magnetic field sensing) with an optical angle sensor that uses light reflection principles. This substitution eliminates the vulnerability to external magnetic interference while maintaining angle detection capability through optical means instead of electromagnetic means.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a detected target with a specific outer contour as an intermediary between the rotation shaft and the proximity sensor. This target reflects light to the sensor, creating an optical measurement pathway that is immune to magnetic interference while accurately representing the rotational position.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If conventional optical angle sensor is used, then optical sensing is implemented, but sensing accuracy is poor

Engineering Contradiction:

Improvesensing accuracyVSAvoid[inferred: device structure complexity]

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a detected target with an asymmetric outer contour where different radial positions (first detected position and second detected position) are at different distances from the virtual axis. This asymmetry creates distinct light reflection patterns for different rotational positions, enabling the proximity sensor to accurately determine angle by detecting reflected light intensity variations.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes the geometric parameters of the detected target, specifically designing an outer contour with varying radial distances from the virtual axis. This parameter variation creates a measurable optical signal that correlates directly with rotational angle, improving sensing accuracy through geometric design rather than complex sensor mechanisms.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If high-accuracy angle measurement is achieved, then sensing precision is improved, but device space requirements increase

Engineering Contradiction:

Improveangle measurement accuracyVSAvoiddevice space

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent uses the rotation shaft itself as the mounting structure for the detected target, and the base as the mounting structure for the proximity sensor. This self-service approach eliminates the need for additional housing or mounting structures, achieving high-accuracy angle measurement within the existing device footprint without increasing overall space requirements.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent merges the angle sensing function with the existing rotation shaft and base structures. The detected target is integrated onto the rotation shaft, and the proximity sensor is integrated onto the base, combining multiple functions into existing components rather than adding separate dedicated structures, thereby maintaining compact device space.

Inventive Principle:

Principle #5Merging (Combining)

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 achieves high-accuracy angle measurements in a small space, resistant to external magnetic interference and improves sensing precision beyond conventional optical angle sensors, ensuring reliable feedback control.

Implementation Method 1

the proximity sensor emits light toward the detected target and detects reflected light from the outer contour of the detected target

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS20240168160A1Angle sensing device and angle sensing system

Publication Date: 2024.05.23 ASUSTEK COMPUTER INC

AI summary

An angle sensing device includes a base, a rotation shaft, a detected target, and a proximity sensor. The rotation shaft is rotatably arranged on the base, and includes a side surface and a virtual axis. The detected target is arranged on the side surface, and an outer contour of a cross section of the detected target along a radial direction of the rotation shaft includes a first detected position and a second detected position, where a distance of the first detected position with respect to the virtual axis is different from that of the second detected position. The proximity sensor is fixedly arranged on the base and faces the detected target. When the detected target rotates together with the rotation shaft, the proximity sensor emits light toward the detected target and detects reflected light from the outer contour of the detected target to generate measurement data.