Capacitive Rotary Selector for Washing Machine Control Panel
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Solution Overview
Problem
Conventional rotary program selectors for domestic appliances are mechanically complex, prone to wear, and allow water penetration, while capacitive sensors lack the familiar operating philosophy of rotary selectors.
Innovation Solution
A capacitive touch or proximity sensor device with multiple sensor electrodes attached to a cylindrical base body protruding from the control panel, allowing sliding or touching movements to select functions without mechanical connections, mimicking the rotary selector experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical rotary program selector is used, then the familiar operating philosophy and rotary selector experience are maintained, but the device becomes mechanically complex and prone to wear
Solution Approach 1:
The patent replaces the mechanical rotary selector system with a capacitive sensor system. Instead of using mechanical components like rotating shafts and contacts, the invention uses capacitive sensing technology to detect the position and movement of the operating element. This substitution eliminates mechanical complexity and wear while preserving the rotary operating experience through capacitive detection of rotational position.
Solution Approach 2:
The patent creates a capacitive copy of the mechanical rotary selector's functionality. The capacitive sensor array replicates the rotational position detection capability of the mechanical system without requiring mechanical contacts. By mapping capacitive sensor readings to rotational positions, the system copies the operating experience of a mechanical rotary selector while using entirely different (non-mechanical) sensing principles.
2Ease of operation
If a mechanical rotary program selector is used, then the rotary selector experience is maintained, but water and dirt can penetrate into the interior of the household appliance
Solution Approach 1:
The patent eliminates mechanical connections between the control panel and internal components by replacing the mechanical rotary selector with a capacitive sensor system. The capacitive sensors are integrated into the control panel surface, requiring no through-openings or mechanical shafts that would allow water and dirt penetration. This maintains the rotary operating experience while creating a sealed control panel structure.
3Reliability
If capacitive touch and proximity sensors are used, then the device is cheaper and less subject to wear and tear, but the operating philosophy of a conventional rotary selector cannot be maintained
Solution Approach 1:
The patent divides the capacitive sensing system into multiple discrete sensor elements arranged in a pattern that corresponds to rotational positions. By segmenting the sensing area into multiple capacitive sensors, the system can detect which specific sensor is activated or the pattern of activation, thereby determining rotational position. This segmentation allows the capacitive system to replicate the discrete position detection of a mechanical rotary selector.
Solution Approach 2:
The patent transitions from a single-point capacitive sensor to a distributed array of capacitive sensors across the control panel surface. This dimensional expansion from one sensor to multiple sensors arranged in a geometric pattern enables the system to detect not just presence but also position and rotational angle, thereby maintaining the rotary selector operating philosophy through capacitive means.
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, wear-free operating device that maintains the familiar rotary selector experience while preventing water ingress and enhancing user-friendliness and reliability.
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.
Data Source
Figure 1~2
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 (8) which are electrically insulated from each other and which are electrically coupled to an evaluation circuit. The sensor electrodes (8) are fitted on a base body (3) of a control element (4) projecting from a control panel (2). The invention further relates to a domestic appliance, especially for treating laundry, comprising said control device.