Control Panel With Mechanical Switches Inside Capacitive Sensor Area
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Solution Overview
Problem
Existing control panels with both touch sensitive and mechanical inputs face issues such as gaps leading to dirt and liquid ingress, mechanical wear, and accidental switch activation due to tilting mechanisms, which compromise their compactness, robustness, and user experience.
Innovation Solution
A control panel design featuring a capacitive position sensing element coupled with a position sensing circuit and at least one mechanical switch, where the switch is electrically coupled or decoupled from the position sensing element, allowing independent operation and reducing sensitivity interference, with a sealed surface to prevent damage from liquids and dirt, and tactile feedback for user interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the platform PCB is tiltably mounted to enable mechanical switch activation, then the control panel can provide both touch-sensitive and mechanical input functions, but the mechanical tilting mechanism is prone to wear and possible eventual failure
Solution Approach 1:
The control panel is divided into separate functional layers: a flexible printed circuit board layer containing mechanical switches, and a separate touch-sensitive overlay layer. This segmentation allows each layer to perform its function independently without mechanical interaction, eliminating wear while maintaining both input modalities.
Solution Approach 2:
The patent combines touch-sensitive sensing capability and mechanical switch functionality into a single integrated control panel structure where both input methods operate through the same physical interface area, providing versatility without requiring separate control surfaces.
2Ease of operation
If the platform PCB is free to tilt about its support, then mechanical switches can be activated by pressing, but switches can be activated by accident by pressing midway between them
Solution Approach 1:
The flexible printed circuit board is segmented into discrete switch regions with defined boundaries. Each mechanical switch is associated with a specific conductive trace or contact area, ensuring that pressing in the region between switches does not create unintended electrical connections or activate unwanted switches.
Solution Approach 2:
Different regions of the flexible printed circuit board have different electrical properties: areas under switch contacts are conductive and connected to switch terminals, while areas between switches are non-conductive or isolated. This local differentiation prevents accidental activation by ensuring that only designated switch regions respond to pressure.
3Area of stationary object
If the capacitive position sensing element and mechanical switches share the same control panel surface, then the footprint of the control panel is reduced, but there is a gap between the platform PCB and the wall causing dirt and liquid ingress
Solution Approach 1:
A flexible printed circuit board is used as the substrate for mechanical switches, allowing the control panel to be constructed as a thin, flat assembly that can be mounted flush against the device wall without creating gaps. The flexible nature of the PCB allows it to conform to the mounting surface while maintaining structural integrity and electrical connectivity.
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 compact, robust, and user-friendly control panel that maintains sensitivity and accuracy while preventing damage from environmental factors and reducing wear, ensuring reliable and intuitive user input handling.
Implementation Method 1
a capacitive position sensing element coupled to a position sensing circuit operable to determine the position of a capacitive load applied to the position sensing element
Data Source
AI summary
A control panel having a touch sensitive position sensor and at least one mechanical switch located within a sensitive area of the position sensor is provided. The position sensor comprises a capacitive position sensing element coupled to position sensing circuitry operable to determine the position of a capacitive load, such as a finger, positioned adjacent to the sensitive area of the position sensing element. The mechanical switch has an open state and a closed state and is arranged such that a contact of the switch is selectively electrically coupled to or decoupled from the position sensing element depending on whether the switch is in the open or closed state. A compact and robust control panel can thus be provided in which the presence of the mechanical switch within the sensitive area of the position sensor does not significantly effect its sensitivity.