Dead-Front Capacitive Touch Switch With Hidden Backlit Icons
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Solution Overview
Problem
Capacitive touch switches in domestic appliances lack effective visual feedback mechanisms to maintain a dead-front user interface, where icons are invisible when not illuminated, resulting in a monochromatic surface appearance.
Innovation Solution
A capacitive touch switch design incorporating a transparent insulating panel, a filtering layer with opaque color, a tinted transparent substrate with capacitive electrodes, and a light source that transmits light through the substrate and panel to create invisible icons when not illuminated, using a light guide and opaque cover to match the filtering layer's color, achieving a dead-front effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional buttons are used in capacitive touch switches, then visual feedback is provided, but the user interface cannot maintain a dead-front appearance with invisible icons when not illuminated
Solution Approach 1:
The patent applies color changes by using a tinted transparent substrate that changes its optical properties when illuminated. The substrate is tinted to match the filtering layer color, and when the light source is off, the icon becomes invisible against the monochromatic background. When illuminated, the icon becomes visible through the light transmission, providing visual feedback while maintaining the dead-front effect.
Solution Approach 2:
The patent introduces a tinted transparent substrate as an intermediary element between the filtering layer and the user. This substrate acts as a mediator that allows the icon to be invisible when not illuminated by matching the filtering layer's color, and becomes visible when illuminated, thus enabling the dead-front effect without requiring complex mechanical buttons.
2Loss of information
If icons are made visible on the panel, then user feedback is provided, but the monochromatic dead-front surface appearance is lost
Solution Approach 1:
The patent uses color changes to achieve the desired effect. The transparent substrate is tinted to substantially match the opaque color of the filtering layer. When the light source is off, the substrate's tint matches the filtering layer, making the icon invisible and maintaining the monochromatic dead-front appearance. When the light source is on, the icon becomes visible through light transmission, providing necessary information feedback.
Solution Approach 2:
The patent applies dynamics by making the icon's visibility dynamic rather than static. The icon transitions from invisible to visible state based on the illumination condition. This dynamic behavior allows the interface to maintain a clean monochromatic appearance when not in use, while providing clear visual feedback when activated, resolving the contradiction between visibility and monochromatic surface.
3Device complexity
If a transparent substrate is used to allow light transmission, then the dead-front effect is achieved, but the substrate must be precisely tinted to match the filtering layer color
Solution Approach 1:
The patent addresses the manufacturing precision challenge by specifying that the transparent substrate be tinted to substantially match the opaque color of the filtering layer. This color matching approach, combined with the use of a light source that transmits through the substrate and panel, enables the dead-front effect while providing a practical manufacturing solution that balances precision requirements with achievable tolerances.
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 user interface that appears monochromatic when icons are not illuminated, enhancing the dead-front effect by allowing light transmission through tinted substrates and matching colors, ensuring a seamless, low-profile user experience.
Implementation Method 1
a light source configured to transmit light through the transparent substrate, the transparent icon, and the transparent insulating panel when energized
Implementation Method 2
detects the proximity or position of a user (typically, a user's finger) via a change in the capacitance of one or more electrodes
Data Source
AI summary
A capacitive touch switch is disclosed which includes a transparent insulating panel, a filtering layer having an opaque color, a transparent icon being defined in the filtering layer, a transparent substrate including a capacitive electrode, the transparent substrate being tinted to substantially match the opaque color of the filtering layer, and a light source configured to transmit light through the transparent substrate, the transparent icon, and the transparent insulating panel when energized. A user interface and a method of manufacturing a capacitive touch switch are also disclosed.