Capacitive Crown Assembly for Multi-Axis Force Input Detection
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Solution Overview
Problem
Existing input mechanisms in small form factor devices, such as watches, lack the ability to detect non-binary amounts of force applied, limiting their functionality in receiving varied user inputs.
Innovation Solution
An input mechanism, such as a crown, equipped with force sensors that utilize capacitance changes between conductive elements and compliant materials to determine the amount of force applied, allowing for rotation, translation, and transverse movement inputs, processed by a unit to interpret different force levels as distinct inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional input mechanisms are used in small form factor devices, then the device maintains a compact size, but the input mechanism cannot detect non-binary amounts of force applied
Solution Approach 1:
The patent replaces traditional mechanical force sensing mechanisms with a capacitive sensing system. The capacitive sensor detects force applied to the crown through changes in capacitance between conductive elements, eliminating the need for complex mechanical force sensors while enabling non-binary force detection in a compact form factor
Solution Approach 2:
The patent utilizes changes in capacitance as a parameter to detect force magnitude. By measuring the change in capacitance between conductive elements when force is applied to the crown, the system can determine the amount of force applied, transforming a mechanical parameter (force) into an electrical parameter (capacitance) for precise measurement
2Adaptability or versatility
If force sensors are added to the input mechanism, then the ability to detect different force levels is improved, but the device complexity increases
Solution Approach 1:
The patent makes the crown input mechanism multi-functional by enabling it to detect not only rotational and translational movements but also the magnitude of force applied. The same capacitive sensing structure serves multiple detection purposes, allowing the device to interpret various input types (rotation direction, translation distance, force magnitude) through a single integrated mechanism
Solution Approach 2:
The patent introduces compliant material as an intermediary between the crown and the capacitive sensor. This compliant material transfers the mechanical force from the crown to the capacitive sensor while allowing for the necessary mechanical movement, enabling force detection without directly coupling the sensor to the moving crown structure
3Measurement precision
If the input mechanism structure is modified to include capacitive sensing elements, then force detection capability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent employs thin film capacitive elements and compliant materials in the collar assembly. These thin film structures can be manufactured using standard thin film deposition and patterning techniques, allowing for precise capacitive sensing elements to be integrated into the collar assembly without requiring complex mechanical force sensor fabrication processes
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 the electronic device to receive a variety of inputs based on different force levels, enhancing user interaction by accurately measuring and interpreting force applied through various movements.
Implementation Method 1
The collar includes a moveable conductor, a conductive element, and a separation defined between the moveable conductor and the conductive element. Movement of the input structure changes a capacitance between the moveable conductor and the conductive element.
Data Source
AI summary
An input mechanism, such as a crown, detects amounts of applied force. In various examples, an assembly including an input mechanism has an enclosure; a stem coupled to the enclosure such that the stem is rotatable, translatable, and transversely moveable with respect to the enclosure; a sensor, coupled between the stem and the housing, to which force is transferred when the stem moves with respect to the housing; and a processing unit coupled to the sensor. The processing unit is operable to determine a measurement of the force, based on a signal from the sensor.