Capacitive Knob With Segmented Conductive Terminals
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Solution Overview
Problem
The existing input devices with capacitive touch panels often experience non-detection or erroneous detection of finger touches due to small differences in capacitance between non-touch and touch states.
Innovation Solution
A knob design featuring a ring-shaped conductive operation portion, a rotary non-conductive supporting member, and multiple conductive terminal portions with varying surface areas, which enhances the capacitance difference detection by the touch panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single conducting terminal portion is used, then the device structure is simple, but the capacitance difference detection is insufficient leading to non-detection or erroneous detection
Solution Approach 1:
The conducting terminal portion is divided into multiple segments (first conducting terminal portion and second conducting terminal portion) with different surface areas. This segmentation allows the system to detect capacitance changes more accurately by comparing signals from multiple terminals, thereby resolving the contradiction between detection precision and structural simplicity.
Solution Approach 2:
Different regions of the conducting terminal portion are given different surface areas (local quality variation). The first conducting terminal portion has a larger surface area while the second has a smaller surface area, creating localized differences in capacitance characteristics that improve detection accuracy without requiring complete structural redesign.
2Measurement precision
If the capacitance difference is small, then the touch detection sensitivity is reduced, but increasing the terminal surface area increases the device size
Solution Approach 1:
Instead of using a single large terminal portion that would increase device size, the system segments the terminal into multiple portions with different areas. This allows the smaller second conducting terminal portion to be positioned strategically to enhance capacitance difference detection without proportionally increasing the overall device area.
Solution Approach 2:
The system changes the parameter of surface area distribution across different terminal portions rather than uniformly increasing all terminal areas. By varying the surface area parameter locally (larger first terminal, smaller second terminal), the system optimizes capacitance detection sensitivity while controlling overall device dimensions.
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 effectively prevents non-detection and erroneous detection of finger touches, improving the accuracy of touch detection on the knob.
Implementation Method 1
the capacitance of the touch panel changes depending on the current. The touch panel detects a touch of a finger on the basis of the difference between the capacitance at the time of non-touch of any finger and the capacitance at the time of the touch of the finger
Data Source
AI summary
It includes a knob including: an operation portion comprised of a ring-shaped conductive material, a rotational operation being performed on the operation portion; a rotary supporting member comprised of a ring-shaped non-conductive material and fixed onto a capacitive type touch panel, for rotatably supporting the operation portion; a ring-shaped concave groove disposed in the rotary supporting member; and a conductive conducting terminal portion electrically connected to the operation portion and rotating inside the concave groove integrally with the operation portion, the position of the conducting terminal portion being detected by the touch panel, wherein the conducting terminal portion is comprised of a plurality of conducting terminal portions, surfaces of the conducting terminal portions being in contact with the concave groove, at least two of the surfaces of the conducting terminal portions being different in contact area from each other.