Rotated Capacitive Touch Screen Electrode Layout for Lower Path Losses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As touch screens increase in size, the electrical paths become longer, leading to increased losses and reduced signal-to-noise ratio (SNR), making it challenging to reliably sense touches across large surfaces.
Innovation Solution
The touch screen design incorporates a first array of touch pads and a second array of touch pads that are galvanically isolated, with drive lines and read lines extending at an angle to the length direction, reducing the worst-case path length and impedance, and utilizing mutual capacitance between neighboring touch pads for sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of touch screens increases, then the display area is enlarged, but the electrical paths become longer and losses increase
Solution Approach 1:
The patent applies dimensionality change by rotating the electrode array from a conventional grid alignment to a rotated configuration where drive lines and read lines are angled relative to the screen edges. This geometric transformation reduces the maximum path length through the display area, thereby minimizing electrical losses while maintaining the full display surface area.
Solution Approach 2:
The patent segments the electrode array into multiple independently controllable regions with separate drive lines and read lines. This segmentation allows for reduced path lengths in each region while collectively covering the entire display area, effectively reducing overall electrical losses without compromising the enlarged display area.
2Area of stationary object
If the size of touch screens increases, then the display area is enlarged, but the signal-to-noise ratio decreases
Solution Approach 1:
By rotating the electrode geometry, the patent reduces the maximum electrical path length through the display, which minimizes resistance and capacitance effects. This dimensional change results in improved signal-to-noise ratio while preserving the enlarged display area for touch sensing.
Solution Approach 2:
The patent changes the geometric parameters of the electrode array by introducing rotation angles and adjusted spacing between drive lines and read lines. These parameter modifications optimize the electrical characteristics to improve signal-to-noise ratio while maintaining the required display area.
3Loss of energy
If multiple individual screens are used to solve long path losses, then the path length is reduced, but the device complexity increases
Solution Approach 1:
The patent merges multiple electrode arrays into a single integrated touch screen by implementing a rotated grid configuration that reduces path lengths without requiring separate screens. This combining approach maintains the benefits of short paths while avoiding the complexity of multiple independent display devices.
Solution Approach 2:
Instead of using multiple separate screens, the patent applies a dimensional change by rotating the electrode geometry within a single screen. This approach reduces effective path lengths while maintaining a unified device structure, thereby avoiding the complexity associated with multiple individual screens.
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 signal-to-noise ratio (SNR) and allows for reliable touch detection on large screens by minimizing path length and impedance, particularly beneficial for high aspect ratio screens.
Implementation Method 1
The capacitive based sensing is generally based on a change in a mutual capacitance between individual ones of the drive lines and individual ones of the read lines
Implementation Method 2
however, self-capacitance changes may also be used for the sensing
Implementation Method 3
the change in capacitance comprises a perturbation of electric field lines between neighbouring touch pads. Such a perturbation of the electric field may come about, for example, due to the presence of a foreign object such as a user's finger
Data Source
AI summary
A touch screen is disclosed having a length and a height, and comprising interspaced and galvanically isolated first and second arrays of touch pads; wherein the first array of touch pads comprises a plurality of first strings of series-connected touch pads, each first string forming a drive line and extending in a first general direction; wherein the second array of touch pads comprises a plurality of second strings of series-connected touch pads, each second string forming a read line and extending in a second general direction, different to said first general direction; wherein the first general direction and the second general direction are each different from the length direction; and wherein the touch screen is configured for capacitive-based sensing which may be based on a change in a mutual capacitance between individual ones of the drive lines and individual ones of the read lines.