Lit Capacitive Touch Keypad With Bubble-Free Light Guide Contact
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Solution Overview
Problem
Existing capacitive touch-sensitive key devices for domestic electrical appliances lack visibility of their operating state, and previous illumination solutions using gluing methods disrupt the sensitive switch's operation due to air bubbles and fixed positioning issues.
Innovation Solution
A capacitive touch-sensitive key device with a solid, opaque detection face that incorporates a light guide with a solid diffusion surface, pressed against an electrically insulating plate by an elastic intermediate part, allowing illumination of an icon on the plate without openings, ensuring reliable detection and adjustable positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a light source and light conductor are used to illuminate the control button, then the operating state of the sensitive key becomes visible, but air bubbles in the adhesive tape disrupt the sensitive switch's operation
Solution Approach 1:
The patent removes the adhesive tape that causes air bubbles from the system. Instead of using adhesive to attach the light guide to the control panel, the light guide is integrated directly into the control button structure, eliminating the source of detection disruptions while maintaining illumination functionality
Solution Approach 2:
The patent combines the light guide, control button, and sensitive switch into a single integrated structure. The light guide becomes an inherent part of the button assembly rather than a separate component requiring adhesive attachment, ensuring that illumination and detection functions work together without interference
2Ease of manufacture
If the light guide is fixed by gluing to the glass or printed circuit, then the light source can be connected, but the positioning cannot be adjusted and deformations are not accommodated
Solution Approach 1:
The patent introduces a flexible connection between the light guide and the control panel that allows for positional adjustment and accommodation of deformations. The light guide is designed with flexibility to adapt to panel deformations while maintaining optical contact, transforming a static fixed position into a dynamic adaptable connection
Solution Approach 2:
The light guide is constructed as a flexible component that can bend and adapt to the contours of the control panel. This flexible structure allows the light guide to maintain contact with the panel surface even when the panel deforms, eliminating the need for rigid gluing while ensuring proper positioning
3Shape
If adhesive tape is used to attach the light conductor, then the light guide can be positioned, but dielectrics are generated that cause disturbances in control button operation
Solution Approach 1:
The patent completely removes the adhesive tape from the system by integrating the light guide directly into the control button structure. This eliminates the dielectric layer and air bubbles that cause detection disturbances, while the light guide positioning is achieved through the integrated structure rather than adhesive attachment
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 reliable and disturbance-free detection of touch while illuminating an icon, minimizing costs and ensuring all sensitive keys can be used for various functions with a single reference, maintaining the capacitive effect's sensitivity and ease of control.
Implementation Method 1
The light source is arranged at a distance from the control button and radiates into the light conductor arranged under the window. The light is conducted in the light guide in the direction of the control button.
Implementation Method 2
said light guide comprising a solid light diffusion surface intended to be pressed against an inner surface of the electrically insulating plate
Implementation Method 3
Such devices make it possible to detect the presence of an element such as a user's finger through an electrically insulating body. In practice, the fact of placing a finger in a zone opposite a sensitive key has the effect of generating a variation in capacity
Implementation Method 4
said solid light-diffusing surface being pressed against the inner surface of the electrically insulating plate by an elastic intermediate part of the sensitive key
Data Source
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AI summary
The device (1) has a light guide (7) with a light diffusion solid surface (11) flatten against a lower surface of an electrically insulating plate constituted of a control strip. A transparent/translucent part of the plate is realized opposite to an opaque solid detection face (5) of a sensitive key (4) for allowing passage of the light emitted by a luminous source (13) and diffused through the guide. An icon is represented on the plate and realized on a part of a zone defined by the projection of the face on the plate. The solid surface covers a surface of the icon represented on the plate.