Capacitive Switch Base Body With Low-Pressure PCB Fixation
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Solution Overview
Problem
Conventional capacitive switches face challenges in securely fixing circuit boards while maintaining electronic and optical signal transmission, often requiring complex and costly manufacturing processes that can damage the circuit board during fixation.
Innovation Solution
The design features a base body with axial elevations on the inside of the base plate and recesses on the circuit board, allowing for simple alignment and fixation without compromising signal transmission, using low-pressure, low-temperature injection molding for cost-effective and gentle fixation, and allowing for interchangeable decorative elements to reduce production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the circuit board is fixed in the base part using conventional transparent injection molding or two-component molding, then the circuit board is securely fixed and optical signals can be transmitted, but the fixation process occurs at high pressures (up to 200 bar) and high temperatures (over 200 °C) which can damage the circuit board, especially the soldering points
Solution Approach 1:
The patent changes the critical parameters of the injection molding process by using a one-component molding material that cures at low temperature (room temperature or slightly elevated) and low pressure. This eliminates the high temperature (over 200°C) and high pressure (up to 200 bar) conditions of conventional two-component molding, thereby preventing damage to the circuit board and its soldering points while still achieving secure fixation.
2Ease of manufacture
If the base plate is transparent throughout and decorative elements are arranged directly on the circuit board, then alignment of the circuit board in the base part can be omitted, but this does not allow interaction of structures on the base plate with signal emitters and requires cost-intensive decorative post-processing of the circuit board
Solution Approach 1:
The patent segments the base plate into functionally distinct zones: transparent sections for optical signal transmission and opaque sections for decorative elements and signal emitter interaction. This segmentation allows the base plate to simultaneously provide structural support, optical transparency where needed, and decorative functionality, eliminating the need for circuit board alignment while enabling versatile optical interactions.
Solution Approach 2:
The base plate acts as an intermediary element between the circuit board and the external environment. By incorporating both transparent and opaque sections directly into the base plate structure, it mediates between the need for circuit board protection, optical signal transmission, and decorative functionality without requiring direct mounting of decorative elements on the circuit board.
3Loss of information
If an interaction between structuring on the base plate and optical signals is provided, then information can be transmitted to the user, but a complex alignment of the circuit board in the base part is required while the circuit board is being fixed
Solution Approach 1:
The patent performs preliminary action by pre-integrating the optical interaction structures directly into the base plate during its manufacturing process. The transparent and opaque sections are built into the base plate structure before the circuit board is installed, eliminating the need for complex alignment operations during assembly. The circuit board can be simply placed into the base part without requiring precise positioning for optical interactions.
Data Source
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AI summary
The base body (1) for a capacitive switch, has a flat actuating surface for releasing the switch and a base unit (2), which is partially transparent. A base plate (3) has an axial projection at its inner face, where a board has recesses. The projections of the base plate are arranged in the recesses of the board. A light emitting diode is arranged on a side of the board facing away from the inner side of base plate of the base unit. An independent claim is included for a capacitive switch with a covering element.