Rotary Input Electrode Layout for Stable Capacitance Detection
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Solution Overview
Problem
Existing rotation input devices face challenges in stably detecting rotation due to limitations in spring length and electrode area, leading to unstable capacitance detection and erroneous position detection of the holding electrode part.
Innovation Solution
The rotation input device design includes a configuration where the contact spring portion extends from the fixed electrode via a folded portion, allowing for increased spring length and electrode area, enhancing stable capacitance detection and accurate rotation angle sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the spring length of the contact spring portion is increased, then the area of the fixed electrode is reduced, but this leads to unstable capacitance detection and difficult position detection
Solution Approach 1:
The contact spring portion is configured to extend in the axial direction (vertical dimension) rather than only in the radial direction, utilizing the Z-axis dimension to increase spring length without reducing the radial area of the fixed electrode. This dimensional transition allows both parameters to be optimized simultaneously.
Solution Approach 2:
The contact spring portion with its folded configuration is nested within the space defined by the fixed electrode structure, allowing the spring to achieve sufficient length through folding while remaining within the overall device footprint and not encroaching on the electrode's functional area.
2Area of stationary object
If the area of the fixed electrode is increased, then the spring length of the contact spring portion cannot be increased
Solution Approach 1:
The contact spring portion transitions from radial extension to axial extension, utilizing the vertical dimension to achieve the necessary spring length while preserving the radial area of the fixed electrode for optimal capacitance detection.
3Device complexity
If the contact spring portion extends directly from the fixed electrode, then the structure is simple, but the spring length is insufficient for stable electrical connection
Solution Approach 1:
The contact spring portion incorporates a folded configuration that provides dynamic elasticity and sufficient length while maintaining a relatively simple overall structure. The folding allows the spring to achieve the necessary length and compliance for stable electrical connection without requiring complex multi-component assemblies.
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 design stabilizes capacitance detection and suppresses erroneous rotation operation detection by ensuring reliable electrical connections and precise position sensing of the fixed electrodes, even at varying rotation angles.
Implementation Method 1
a plurality of contact spring portions that are in elastic contact with the code portion and in which a state of an electrical connection with the code plate switches in accordance with a rotation angle of the rotary body
Implementation Method 2
a technique for detecting rotation of a rotary part in an input device based on a change in an electrical connection state between a holding electrode part and a rotary electrode part
Data Source
AI summary
A rotation input device includes a fixing body having an attachment surface, a rotary body supported by the fixing body in such a manner that the rotary body is rotatable around an axial direction orthogonal to the attachment surface, a rotating electrode attached to the rotary body, a plurality of fixed electrodes attached to the fixing body at respective positions along a circumferential direction around the axial direction, a code plate attached to the rotary body and having a code portion, and a plurality of contact spring portions integrally extending from the respective fixed electrodes and being in elastic contact with the code portion. The contact spring portion extends from an end portion of the fixed electrode in the circumferential direction toward the code portion via a folded portion.