Capacitive Force Touch Sensor With Shielded Backlighting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive touch sensors are prone to false triggering due to water, oil, mud, food products, and metallic objects, and suffer from multiple activations when multiple sensors are proximal, lacking effective shielding and backlighting capabilities.
Innovation Solution
A capacitive touch sensor design featuring a capacitive sensor element, a physically deformable electrically insulating spacer, and a conductive deformable plane connected to a power supply, with a protective cover for environmental sealing and backlighting through a suspended metallic target and light-emitting diodes, ensuring accurate activation and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous conductive metal sheet is used for the target layer, then the sensor provides good electrical conductivity and shielding, but it blocks light and prevents backlighting
Solution Approach 1:
The continuous conductive metal sheet is segmented into discrete conductive elements or patterns that maintain electrical connectivity while creating openings for light transmission. This segmentation allows the target layer to provide shielding and conductivity functions while permitting backlight to pass through the gaps between conductive elements.
Solution Approach 2:
The target layer is designed with spatially varying properties - conductive material is concentrated in specific patterns or regions while leaving other areas transparent or less conductive. This local differentiation allows simultaneous optimization of shielding in critical areas and light transmission in backlighting areas.
2Length of moving object
If the sensor uses a simple flat spacer layer less than 50 micrometers thick, then the device is mechanically thin and compact, but it cannot provide effective physical force detection and backlighting
Solution Approach 1:
The spacer structure transitions from a simple two-dimensional flat layer to a three-dimensional structured form with varying thickness, recesses, or raised portions. This dimensional change enables the spacer to provide mechanical leverage for force detection while maintaining overall device thinness, and creates space for backlighting elements.
Solution Approach 2:
Multiple functional elements are nested within the spacer structure - conductive elements, optical elements for backlighting, and mechanical features for force detection are integrated into the spacer's three-dimensional form, allowing compact packaging of multiple functions within a thin profile.
3Ease of manufacture
If the sensor element is exposed without environmental sealing, then the structure is simple and easy to manufacture, but it is vulnerable to fluid contamination and false triggering
Solution Approach 1:
A thin flexible protective cover or seal layer is introduced over the sensor elements. This thin film provides environmental protection against fluids and contaminants while maintaining optical transparency for touch detection and backlighting. The flexibility allows the cover to conform to the sensor structure without adding significant thickness or complexity.
4Productivity
If multiple sensors are arranged in close proximity in a matrix, then the device achieves high functionality and compact layout, but adjacent sensors trigger each other due to proximity of user contact
Solution Approach 1:
The conductive target layer is segmented into discrete elements associated with each sensor, with non-conductive spacing between them. This segmentation creates electrical and functional isolation between adjacent sensors, preventing cross-triggering while maintaining close physical spacing for compact matrix layout.
Solution Approach 2:
Non-conductive spacer material or insulation layers are introduced between adjacent sensor elements as intermediary barriers. These intermediaries prevent electrical coupling or capacitive coupling between neighboring sensors that would cause false triggering, while allowing the sensors to remain in close proximity for high-density arrangement.
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 immunity to false triggering and fluid contamination, while enabling effective backlighting for improved user feedback and visibility, ensuring accurate and reliable sensor activation.
Implementation Method 1
The capacitive touch sensors are activated (controls a signal indicating activation) by a change in capacitance of the capacitive touch sensor when an object, e.g., user finger tip, causes the capacitance thereof to change
Implementation Method 2
backlighting through a suspended metallic target and light-emitting diodes
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A physical force capacitive touch sensor comprises a capacitive sensor element on a substrate, a physically deformable electrically insulating spacer over the capacitive sensor element and a conductive deformable plane over the physically deformable electrically insulating spacer. A protective deformable fascia may be placed over the conductive deformable plane to provide an environmental seal for physical and weather protection, but is not essential to operation of the capacitive touch sensor. Back lighting is accomplished through a light transmissive layer(s) in the capacitive touch sensor. When the conductive deformable plane is displaced toward the capacitive touch sensor element, the capacitance value of the capacitive touch sensor element changes and that change may be detected and used as an actuation signal.