Capacitive Switch Assembly With Shielded Single-Sensor Actuation
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Solution Overview
Problem
Existing capacitive switching devices are expensive to produce and time-consuming to assemble, and they fail to effectively detect mechanical movements due to the use of multiple sensor elements and non-elastically deformable materials, which limits their functionality in converting manual infeed movements into electrical signals.
Innovation Solution
A capacitive switching device with a single sensor between the housing and a conductive screen that acts as both a shield and a seal, allowing for easy assembly and cost-effective manufacturing, utilizing an elastically deformable screen to accommodate axial movements and generate electrical signals based on changes in the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three different sensor elements are used to detect mechanical movements, then measurement precision is improved, but manufacturing cost and assembly complexity increase
Solution Approach 1:
The patent combines the functions of multiple sensor elements into a single capacitive sensor. The first sensor element fixed to the housing and the second sensor element on the movable assembly work together as a unified capacitive sensing system, eliminating the need for multiple separate sensor components and their complex alignment while maintaining movement detection capability
Solution Approach 2:
The conductive screen serves multiple functions simultaneously: it acts as a shield for the electric field, provides structural support for the movable assembly, and functions as one of the capacitive sensor elements. This multi-functionality reduces the overall component count and simplifies the device structure
2Measurement precision
If three different sensor elements are used to detect mechanical movements, then measurement precision is improved, but assembly time increases
Solution Approach 1:
The patent combines the functions of multiple sensor elements into a single capacitive sensor. The first sensor element fixed to the housing and the second sensor element on the movable assembly work together as a unified capacitive sensing system, eliminating the need for multiple separate sensor components and their complex alignment while maintaining movement detection capability
Solution Approach 2:
The conductive screen is pre-formed with the required geometric shape and electrical properties before assembly. The seal and mounting structures are prepared in advance to automatically position the screen and sensor elements in the correct locations, eliminating time-consuming alignment operations during final assembly
3Stability of the object's composition
If a dimensionally stable material is used for the screen, then structural stability is improved, but the ability to detect actuation forces is reduced
Solution Approach 1:
The patent employs a flexible or elastically deformable conductive screen that can dynamically change its shape or position in response to applied forces. This dynamic behavior allows the screen to translate mechanical actuation into detectable changes in the capacitive field, enabling reliable force detection while maintaining structural integrity
Solution Approach 2:
The patent changes the physical parameters of the screen material from dimensionally stable to flexible or elastically deformable. This parameter change enables the screen to undergo controlled deformations under actuation forces, which are then detected by the capacitive sensor as changes in capacitance or electric field distribution
4Reliability
If the sensor is shielded from external influences, then measurement reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The conductive screen serves multiple functions simultaneously: it acts as a shield for the electric field, provides structural support for the movable assembly, and functions as one of the capacitive sensor elements. This multi-functionality reduces the overall component count and simplifies the device structure while maintaining shielding effectiveness
Solution Approach 2:
The patent combines the shielding function with the structural and sensing functions in the conductive screen. Rather than adding a separate shielding layer, the screen itself is designed to provide both mechanical support and electromagnetic shielding, reducing overall device complexity
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 solution enables quick and cost-effective manufacturing while maintaining functionality, allowing for reliable detection of mechanical movements and generation of electrical signals, with the elastically deformable screen providing a restoring force and shielding against external influences.
Implementation Method 1
a capacitively operated sensor (21) between the housing (4) and the cover plate (7)
Implementation Method 2
generates an electric field (23) that extends towards the screen (22)
Implementation Method 3
The switching device according to the invention is characterized in that the screen (22) is designed to be elastically deformable
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3c
AI summary
In a capacitive switching device (1) for converting a manual or mechanical actuation movement (2) into an electrical switching signal by which an electrical device is controlled, comprising: - a housing (4) in which a receiving opening (5) is incorporated, - a touchscreen (6) arranged in the receiving opening (5) of the housing (4), which is enclosed externally by an electrically insulating cover plate (7) and internally by a display (8), - wherein the cover plate (7), the touchscreen (6) and the display (8) form a unit (9) which is axially movably mounted in the receiving opening (5) of the housing (4), - wherein the touchscreen (6) and the display (8) have at least one capacitively operated button (10) which is switched when a human finger or a mechanical actuation element approaches it, - and evaluation electronics (12) electrically coupled to the respective button (10),By generating a switching signal corresponding to the respective button (10) when the electric field (23) changes, a simple and cost-effective manufacturing and assembly of the switching device (1) with a suitable sensor arrangement (21) is to be provided while maintaining the functionality of the switching device (1). This is achieved by: - providing a capacitively operated sensor (21) between the housing (4) and the cover plate (7), - and by arranging a shield (22) made of an electrically conductive material between the sensor (21) and the cover plate (7), through which the sensor (21) is capacitively isolated from the outside and which generates a common electric field (23) with the sensor.