Three-Axis Magnetic Sensor for Rotatable Display Angle Detection

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Solution Overview

Problem

Existing computing devices with rotatably coupled substrates face challenges in accurately determining angular orientations between substrates, particularly when the hinge axis is aligned with gravity, leading to errors in angle estimation and performance degradation in high-vibration scenarios.

Innovation Solution

A computing device is designed with a first planar substrate featuring a magnet array and a second planar substrate with a three-axis magnetic sensor. The magnet array generates a magnetic field within an array plane normal to the array axis, and the three-axis magnetic sensor senses this magnetic field to determine multiple angular orientations between the substrates throughout a range of degrees.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a magnetic sensor is used to detect angular orientation of rotatably coupled substrates, then the device can determine relative angles between displays, but the measurement precision deteriorates when the hinge axis is aligned with gravity

Engineering Contradiction:
Improveangular orientation detection accuracyVSAvoidperformance in gravity-aligned scenarios
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent transitions from using a single-axis magnetic sensor to a three-axis magnetic sensor, adding two dimensions of measurement. This allows the system to detect magnetic field components along X, Y, and Z axes simultaneously, enabling accurate angle determination even when the hinge axis aligns with gravity by utilizing the additional spatial dimensions for reference measurements.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the measurement parameters by incorporating multiple magnetic sensors oriented at different angles (e.g., 0°, 45°, 90°, 135°) relative to the hinge axis. This allows the system to collect magnetic field data from multiple orientations and compute the most accurate angle measurement regardless of the hinge's gravitational alignment, effectively changing how the measurement is taken rather than relying on a single fixed parameter.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If multiple sensors are added to improve angle detection accuracy, then measurement precision improves, but device complexity increases

Engineering Contradiction:
Improveangular orientation detection accuracyVSAvoidsensor array configuration
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The three-axis magnetic sensor performs multiple functions simultaneously: it detects magnetic field strength and direction along three orthogonal axes, enabling the system to determine angular orientation without requiring separate sensors for each axis. This multi-functional approach achieves high measurement precision while avoiding the complexity of installing and coordinating multiple single-axis sensors.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines three independent magnetic field detection capabilities into a single three-axis magnetic sensor component. This merging of functions into one integrated sensor reduces the overall device complexity compared to using three separate sensors, while still providing the comprehensive data needed for accurate angular orientation determination across all possible hinge positions.

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

This configuration allows for accurate determination of angular orientations between substrates, reducing errors associated with gravity-aligned hinge axes and improving performance in high-vibration environments, while also eliminating the need for additional sensors and conserving power.

Implementation Method 1

The first planar substrate comprises a magnet array comprising a first magnet co-axially aligned with a second magnet along an array axis that passes through North and South poles of the first magnet and the second magnet. Like poles of the first magnet and the second magnet face one another to generate a magnetic field within an array plane that is normal to the array axis.

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

The second planar substrate comprises a three-axis magnetic sensor configured to sense magnetic flux along three sensing axes

Methodology Applied
Scientific EffectMagnetic flux sensing: Magnetometer

Data Source

PatentEP4314719B1Rotatably coupled touch screen displays
Publication Date: 2025.02.19 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP4314719B1 patent drawingFigure 1~2
  • EP4314719B1 patent drawingFigure 3~5
  • EP4314719B1 patent drawingFigure 6

AI summary

Examples are disclosed relating to computing devices and methods for determining angular orientations of a first planar substrate rotatably coupled to a second planar substrate. In one example, a method comprises: receiving at a three-axis magnetic sensor in the second substrate a magnetic field emanating from a magnet array in the first substrate; determining magnetic flux densities at first and second sensing axes of the sensor throughout a range of degrees; and using the magnetic flux densities to determine multiple angular orientations of the first substrate relative to the second planar substrate.