Capacitive Touch Display Switch With Scratch-Safe Rotary Push Contacts
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Solution Overview
Problem
Existing rotary/push switches for capacitive touch displays are complex and require numerous components, which can lead to manufacturing inefficiencies and potential damage to the touch display due to contact surfaces.
Innovation Solution
A simplified rotary/push switch design using minimal parts, with a rotor and contact surfaces that are capacitively detected by the touch display, featuring a non-rotatable axle pin and complementary cross-sections for secure connection, and a magnetic or adhesive attachment to the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact surfaces are placed close to the touch display for capacitive detection, then detection sensitivity is improved, but the risk of scratching the touch display increases
Solution Approach 1:
The patent implements a restoring force mechanism (spring or elastic element) that pre-complies with the contact surfaces, maintaining them at a safe distance from the touch display during normal operation. When force is applied, the restoring force allows controlled movement while preventing excessive contact that could cause scratching, thus cushioning against potential damage before it occurs.
Solution Approach 2:
The patent dynamically changes the distance parameter between contact surfaces and touch display based on operational state. In normal state, surfaces are positioned at a safe distance (e.g., 0.05-0.1mm) to prevent scratching. When activated, the distance is reduced to enable capacitive detection, and the restoring force ensures return to the safe position, thus adapting the parameter to meet different functional requirements.
2Reliability
If traditional rotary/push switch designs are used with multiple components, then functional reliability is improved, but manufacturing complexity and assembly time increase
Solution Approach 1:
The patent combines multiple traditional switch components into an integrated structure. The housing serves dual purposes as both structural support and mounting element, the axle journal integrates bearing and positioning functions, and the contact surfaces are incorporated directly into the rotor and stator structures. This merging reduces the number of individual parts while maintaining functional reliability through the cohesive design.
Solution Approach 2:
The patent implements multi-functional components where each element performs multiple roles. The restoring force mechanism provides both positioning and safety functions, the axle journal combines rotational support with axial guidance, and the contact surfaces serve both mechanical and capacitive detection functions. This universality reduces overall component count while maintaining reliability.
3Measurement precision
If contact surfaces are positioned very close to the touch display (less than 0.05mm), then capacitive signal strength is improved, but the risk of mechanical damage to the display increases
Solution Approach 1:
The restoring force mechanism (spring or elastic element) is pre-configured to maintain contact surfaces at a safe distance from the touch display during normal operation. This cushioning mechanism allows the system to approach the display closely for strong capacitive coupling when needed, while the elastic restoring force prevents excessive force that could damage the display, thus protecting mechanical integrity while enabling strong signals.
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
The simplified design reduces manufacturing complexity and minimizes contact surface damage to the touch display, ensuring reliable operation with enhanced signal strength and ease of assembly.
Implementation Method 1
the rotor together with the second contact surface is rotated, which is capacitively detected by the touch display due to the short distance between the second contact surface and the touch display
Implementation Method 2
from an upper end position against the effect of a restoring force, here by means of a snap disc, is guided axially displaceably into a lower end position
Data Source
Figure 1~2b
Figure 3a~4b
Figure 5~7
AI summary
A switch (1) for actuating a capacitive touch display (2) comprises, according to the invention, - a stator (3) with a stator underside which defines a fastening plane (4) for fastening to the touch display (2), and with a bearing opening (5) which defines a rotation axis (6) perpendicular to the fastening plane, - a switch button (7) made of electrically conductive material which is arranged on the stator (3) and which is mounted with a downwardly projecting axle journal (8) in the bearing opening (5) both rotatably about the rotation axis (6) and is also guided axially displaceably from an upper end position against the action of a restoring force into a lower end position, and - a rotor (10) made of electrically conductive material which is arranged on the underside in the stator (3), which is arranged axially immovably in the stator (3) and rotatably about the rotation axis (6) and has a central rotor opening (11) in which athe lower journal end (12) of the axle journal (8) is guided axially displaceably and held non-rotatably to form an electrically conductive connection with the rotor (10), wherein the lower journal end (12) has a first contact surface (13) on the underside which is electrically conductively connected to the switch button (7) and which, in the lower end position of the axle journal (8), is located in or above the fastening plane (4), and wherein the rotor (10) has at least one second contact surface (14) arranged eccentrically to the axis of rotation (6), electrically conductively connected to the switch button (7), which is located in or above the fastening plane (4).