Segmented Capacitive Switch Layout for Dirt-Resistant Sensing
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Solution Overview
Problem
Capacitive switches have limited spatial extent of their capacitive fields, making them prone to disruptions from minor disturbances like dirt particles or water droplets, which limits their application and reliability, especially in sanitary areas where cleaning can cause malfunctions.
Innovation Solution
The capacitive switch design features segments arranged around a common center point, with a non-conductive ring between them, increasing the spatial extent of the capacitive field and allowing it to radiate further, while a cover plate protects against dirt and water, ensuring the field remains uniform and operational.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the capacitive field is designed with a small structure to reduce frame edge area, then the frame size is reduced, but the field strength and radiation height cannot be achieved
Solution Approach 1:
The capacitive field is divided into multiple segments arranged in a specific pattern rather than using a single continuous structure. This segmentation allows the fields to radiate more effectively while maintaining a compact frame design, resolving the contradiction between reduced frame area and sufficient field strength.
2Reliability
If the capacitive field has a limited spatial extent, then the switching distance is reduced, but the switch becomes more sensitive to minor disturbances like dirt particles or water droplets
Solution Approach 1:
By segmenting the capacitive field into multiple separate regions, the patent reduces the impact of local disturbances such as dirt particles or water droplets. A disturbance in one segment does not affect the entire switching function, thereby improving reliability while maintaining adequate switching distance.
Solution Approach 2:
Different segments of the capacitive field can have different characteristics and thresholds, allowing the system to tolerate local disturbances in specific areas while maintaining overall functionality. This local differentiation improves robustness against harmful factors.
3Volume of stationary object
If the capacitive field lines are formed in a dome shape close to the metal layer, then the field structure is compact, but the radiation height and spatial extent are extremely low
Solution Approach 1:
The patent extends the capacitive field configuration from a simple planar dome shape to a three-dimensional segmented arrangement that radiates in multiple directions and distances. This dimensional expansion increases both the radiation height and overall spatial extent of the field while maintaining a compact footprint.
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 significantly increases the switching distance and reliability, allowing the capacitive field to function uniformly even with dirt or water present, and enables effective cleaning without affecting the switch's operation, making it suitable for applications like toilet flushing controls.
Implementation Method 1
The capacitive switch (1) generates a capacitive field (9), which radiates at least five to ten centimeters into space
Implementation Method 2
a cover plate (3) is arranged in the housing frame (2)... it should be ensured that dirt particles or water droplets do not impede the spatial expansion of the capacitive field
Implementation Method 3
These changes in the capacitance field are constantly measured by an integrated circuit arranged adjacent to the copper layer, so that an electrical switching signal can be generated
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
The capacitive switch has a housing frame, by which a cover plate is held, a printed circuit board (4) and an electrically connected layer that is attached on the printed circuit board. The layer runs to the cover plate in a parallel and spaced manner. The layer is formed from segments (11,11',11'') that are separated from each other. The segments are electrically connected with each other.