Reluctance Engine Coil for Gap Sensing and Haptic Feedback

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Solution Overview

Problem

Existing electronic devices with haptic buttons face challenges in providing consistent haptic output due to variations in gap size between moveable and stator components, which affects the accuracy of force sensing and haptic feedback.

Innovation Solution

The implementation of a reluctance engine coil that functions both as a sensing coil and a haptic engine coil, allowing for gap sensing and haptic output control through a single coil assembly, using inductive sensing mode to measure impedance changes and determine gap distance, and switching to haptic drive mode to generate appropriate haptic feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If separate sensing coil and engine coil are used, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvegap sensing accuracyVSAvoidcoil assembly structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the sensing coil and engine coil into a single coil assembly that performs both gap sensing and haptic actuation functions. The coil assembly is mechanically coupled to the button and positioned relative to the stator, allowing it to serve dual purposes: measuring gap distance through impedance changes and generating haptic feedback through electromagnetic actuation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single coil assembly is designed to perform multiple functions: it acts as both a sensing element for gap measurement and an actuating element for haptic feedback. By using the same coil for both sensing and engine functions, the patent eliminates the need for separate components while maintaining measurement precision and haptic performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Manufacturing precision

If impedance measurement is used for gap sensing, then manufacturing precision requirements are reduced, but measurement precision may be affected

Engineering Contradiction:

Improvegap toleranceVSAvoidgap distance accuracy

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent uses impedance measurement as a feedback mechanism to dynamically determine the gap distance between the coil assembly and stator. By monitoring changes in electrical impedance of the coil assembly as the button is pressed, the system can accurately measure gap distance without requiring extremely tight manufacturing tolerances, as the measurement adapts to the actual physical state.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical measurement methods with electrical impedance measurement for gap sensing. Instead of using mechanical gauges or physical contact sensors that would require high manufacturing precision, the system uses the electrical properties of the coil assembly to infer gap distance, thereby reducing manufacturing complexity while maintaining measurement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If haptic drive signal is applied continuously, then haptic output consistency is improved, but energy consumption increases

Engineering Contradiction:

Improvehaptic output consistencyVSAvoidcoil power consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The patent applies haptic drive signals in a periodic or pulsed manner rather than continuously. The controller activates the coil assembly with drive signals at specific intervals or in response to detected button press events, thereby maintaining haptic output consistency when needed while significantly reducing overall energy consumption during idle states.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent dynamically adjusts the application of haptic drive signals based on real-time gap measurements and button press detection. The system activates haptic feedback only when a button press is detected and deactivates it when the button returns to its original position, creating a dynamic on-demand haptic response that maintains consistency during interaction while minimizing energy consumption during non-interaction periods.

Inventive Principle:

Principle #15Dynamics

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 approach enables precise determination of gap distance for consistent haptic output, reducing mechanical stress on measurement components and improving the accuracy of haptic feedback, while simplifying the design by eliminating the need for separate sensing and engine coils.

Implementation Method 1

a coil assembly (220) having a coil (222)

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

gap sensing operation using a reluctance engine coil that triggers operation of a haptic engine

Methodology Applied

Scientific EffectInductive sensing: Electromagnetic Induction

Data Source

PatentUS20240103624A1Gap Sensing Via Engine Coil

Publication Date: 2024.03.28 APPLE INC

AI summary

A haptic engine for an electronic device includes a coil assembly and a stator. The coil assembly may be coupled to an input structure, such as a button cap. In an gap sensing mode, a first voltage may be driven through the coil assembly to determine an impedance of the coil assembly. The impedance is then used to determine a gap between the coil assembly and the stator. In a haptic drive mode, a second voltage is driven through the coil assembly to produce a haptic output.