Capacitive Rotary Program Selector for Wear-Resistant Washer Controls
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Solution Overview
Problem
Existing rotary program selectors for domestic appliances are mechanically complex, prone to wear, and allow water and dirt penetration, while capacitive sensors do not maintain the conventional operating philosophy.
Innovation Solution
A capacitive touch or proximity sensor device with insulated sensor electrodes coupled to a common evaluation circuit, integrated behind an electrically insulating control panel, allowing a mechanically decoupled and wear-resistant operating device that retains the rotary program selector's operating concept.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical rotary program selector is used, then the conventional operating philosophy is maintained, but the device becomes mechanically complex and prone to wear
Solution Approach 1:
The patent replaces the mechanical shaft connection between the rotary operating element and the evaluation circuit with a capacitive sensing system. The operating element remains mechanically rotatable on the control panel, maintaining the familiar operating concept, but the mechanical connection is eliminated. Instead, capacitive sensors detect the position and rotation of the operating element through electrical field changes, substituting mechanical signal transmission with electrical field-based detection.
2Ease of operation
If a mechanical rotary program selector is used, then the operating concept is maintained, but water and dirt can penetrate into the appliance interior
Solution Approach 1:
The patent extracts the mechanical connection shaft from the control panel structure, eliminating the through-opening that allowed water and dirt penetration. The operating element remains on the front panel for user interaction, but the evaluation circuit and its sensors are positioned behind the panel without requiring mechanical penetrations. The capacitive sensing system works through the panel material, allowing the panel to act as a barrier while maintaining sensing functionality.
3Device complexity
If capacitive touch or proximity sensors are used, then mechanical complexity is reduced and wear is minimized, but the conventional rotary operating philosophy cannot be maintained
Solution Approach 1:
The patent makes the operating element serve multiple functions: it remains a mechanically rotatable component that users can physically turn and position (maintaining the familiar rotary selector operation), while simultaneously acting as a capacitive sensor element that detects its own position and rotation through electrical field changes. The operating element functions both as a mechanical interface and an electrical sensing element, combining the benefits of both approaches.
4Ease of manufacture
If a mechanical shaft connection is used, then the operating element can be connected to the evaluation circuit, but the device is subject to wear
Solution Approach 1:
The patent substitutes the mechanical shaft connection with a capacitive coupling system. The operating element and the evaluation circuit are electrically decoupled, with no direct mechanical or electrical contact required. The capacitive sensors detect the position and rotation of the operating element through changes in electrical field capacitance, eliminating the wear inherent in mechanical connections while maintaining full connectivity and signal transmission capability.
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 provides a robust, low-wear operating device that prevents water and dirt ingress, enhancing electrical safety and operational reliability while maintaining the conventional rotary selector's user experience.
Implementation Method 1
If an operator's finger, which carries a potential different from the potential of the sensor electrode, in particular ground potential, approaches the sensor electrode, this causes a change in capacitance of a capacitor having the sensor electrode and the finger. This change in capacitance is then recognized by the evaluation circuit.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a control device for selecting a function from a plurality of functions of a domestic appliance. The control device comprises a capacitive touch or proximity sensor having a plurality of sensor electrodes (3) which are electrically insulated from each other and which are electrically coupled to an evaluation circuit. The sensor electrodes (3) are fitted behind a control panel (2) of the domestic appliance, a control element (7) being movably arranged on the control panel (2) and having a base body (8) and an electrically conductive element (13) fitted on a side (12) of the base body (8) facing the control panel (2), said conductive element capacitively interacting, depending on the position of the control element (7), with at least one of the sensor electrodes (3) when the control element (7) is actuated by an operator. The base body (8) has a first cylindrical part (9) facing the control panel (2) and consisting of an electrically insulating material, and a second cylindrical part (10) directly adjoining the side of the first cylindrical part (9) facing away from the control panel (2) and consisting entirely of an electrically insulating material. The electrically conductive element (13) fastened to the first cylindrical part (9) is electrically coupled to the second cylindrical part (10). The invention further relates to a domestic appliance, especially for treating laundry, comprising said control device.