Capacitive Switch Reflector Region Illumination
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Solution Overview
Problem
Capacitive proximity and touch switches face challenges in providing effective illumination of the operating region without interfering with the sensor signal, particularly when space is limited and electronic light sources may disrupt the sensor functionality.
Innovation Solution
An electrically conductive body with a reflector region is used to deflect light from a laterally positioned light source onto the operating region through a translucent cover plate, allowing for user-friendly illumination while maintaining electrical connectivity and avoiding interference with the sensor signal. The reflector region can be shaped and positioned to achieve homogeneous illumination, even in constrained spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light source is positioned directly above the sensor surface to illuminate the operating region, then the illumination effectiveness is improved, but the light source interferes with the sensor signal and creates dead space above the sensor
Solution Approach 1:
The light source is repositioned from a vertical arrangement (directly above the sensor) to a lateral arrangement (to the side of the sensor). This spatial reconfiguration in another dimension allows the light to reach the operating region through reflection off the electrically conductive body without creating dead space above the sensor or interfering with the sensor signal path.
2Volume of moving object
If the distance between the cover plate and carrier plate is reduced to save space, then the device compactness is improved, but there is insufficient space for conventional light sources
Solution Approach 1:
The illumination system transitions from a vertical light path (requiring height between cover plate and carrier plate) to a lateral light path utilizing the electrically conductive body as a reflector. This dimensional change enables effective illumination within the constrained vertical space by redirecting light horizontally onto the operating region through the translucent cover plate.
Solution Approach 2:
The electrically conductive body serves dual functions: it provides the necessary electrical connection for the capacitive sensor and simultaneously acts as a reflector to illuminate the operating region. This multi-functionality eliminates the need for separate light source components, enabling illumination in compact device configurations.
3Measurement precision
If electronic light sources are used to illuminate the operating region, then the illumination precision is improved, but the device complexity and space requirements increase
Solution Approach 1:
The electrically conductive body is designed to perform both its primary function of providing electrical connection for the sensor and a secondary function of reflecting light to illuminate the operating region. This multi-functional design eliminates the need for separate electronic light source components, reducing device complexity while maintaining effective illumination.
Solution Approach 2:
The electrically conductive body serves itself by utilizing its inherent reflective properties to illuminate the operating region, rather than requiring external illumination components. This self-service approach simplifies the overall device structure while achieving the illumination objective.
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
This solution enables regular and homogeneous illumination of the operating region without compromising the sensor's functionality, allowing for reliable user feedback and actuation detection, while minimizing the need for electronic light sources within the sensor area and maintaining a compact design.
Implementation Method 1
the electrically conductive body has a reflector region configured in such a manner that light emitted from the light source can be deflected in the direction of the operating region by the reflector region
Implementation Method 2
the capacitance of which can be changed by proximity to or contact with the cover plate, which can be evaluated by means of an evaluation circuit
Data Source
AI summary
A capacitive proximity and/or touch switch has an electrically conductive body bridging a spacing distance between an at least partially translucent, electrically insulating cover plate and a carrier plate. The electrically conductive body has a sensor surface at the end thereof facing the cover plate. The sensor surface is connected to an evaluation circuit via the electrically conductive body. A light source is associated with the sensor surface, the light of which implements an optical display in an operating region defined by the sensor surface at the front of the cover plate. The light source is disposed at an offset to the position of the operating region, and the electrically conductive body has a reflector region configured such that light emitted from the light source can be deflected in the direction of the operating region by the reflector region.