Laminated Force-Sensor Input Panel With Backlight Crosstalk Barriers
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Solution Overview
Problem
Capacitive input devices with film layer structures face challenges in effective backlighting due to light interference between adjacent control surfaces, known as 'crosstalk', which complicates the distinction between random contacts and intended actuations and haptic feedback provision.
Innovation Solution
The input device employs a translucent or transparent film layer structure with capacitive sensors and a support, featuring opaque light shafts and conductive coatings to reduce light passage between sensors, along with a scattering layer for improved backlighting and haptic feedback, ensuring distinct visibility and reduced crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transparent or translucent film layer structure is used for capacitive sensors, then the device achieves cost-effectiveness and space efficiency, but light interference between adjacent control surfaces occurs
Solution Approach 1:
Light-absorbing barriers are introduced as intermediary elements between adjacent control surfaces. These barriers absorb stray light that would otherwise interfere with adjacent sensors, thereby eliminating the harmful light interference effect while preserving the transparent/translucent film structure's cost and space advantages.
Solution Approach 2:
The harmful light transmission between adjacent control surfaces is extracted and removed by introducing light-absorbing barriers. These barriers selectively block the unwanted light paths while allowing the film structure to remain transparent for its primary sensing function.
2Volume of moving object
If a transparent or translucent film layer structure is used for capacitive sensors, then the device achieves space efficiency, but backlighting becomes difficult to realize
Solution Approach 1:
Light-absorbing barriers serve as mediators that manage light paths in the compact film structure. They enable effective backlighting by directing and controlling light transmission through the thin film layers, ensuring that backlight reaches the intended control surface without interfering with adjacent areas.
Solution Approach 2:
The film structure is given different local properties: transparent/translucent regions for sensing and light-absorbing barriers for light management. This local differentiation allows the same thin film structure to simultaneously achieve space efficiency and effective backlighting.
3Object-affected harmful factors
If light-absorbing barriers are introduced to reduce crosstalk, then light interference between adjacent control surfaces is minimized, but device complexity increases
Solution Approach 1:
Light-absorbing barriers are implemented as thin film elements integrated into the existing film layer structure. This approach adds minimal structural complexity while effectively reducing light interference, as the barriers conform to the flexible film substrate and are deposited using the same thin-film fabrication processes.
Solution Approach 2:
The device structure becomes a composite of transparent/translucent film regions and light-absorbing barrier regions within the same film layer system. This composite approach allows both functions (sensing and light management) to coexist in a unified structure with minimal added complexity.
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 configuration enhances the visual recognition of control surfaces, prevents operating errors, and provides effective haptic feedback by minimizing light interference while maintaining a cost-effective and space-efficient design.
Implementation Method 1
Each of the capacitive sensors is provided to respectively form a measuring capacitance respectively assigned to one of the several control surfaces
Implementation Method 2
at least one lighting means, in each case for one control surface, is provided on the side of the support for backlighting the control surface and transmitting light through the light-conducting layer
Implementation Method 3
the means for reducing the passage of light from one capacitive sensor to an adjacent one include an opaque coating, in particular a conductive opaque coating, on the film layer structure
Data Source
AI summary
An input device, including a flat panel defining an array of control surfaces, and an array of capacitive sensors and a support. The control surfaces are on a surface of the panel facing towards the operator and the support is on a side of the panel facing away from an operator. Also, each capacitive sensor forms a measuring capacitance assigned to a control surface. Further, each capacitive sensor is formed by a common substantially flat film layer structure. The film layer structure includes a first electrode for forming the measuring capacitance. On the side of the support, a lighting device is provided for each control surface for backlighting the associated control surface and transmitting light through the film layer structure. Also, the input device reduces the passage of light from one capacitive sensor to an adjacent capacitive sensor.