Two-Layer Touch Sensor Segmented Arrays Reduce Capacitive Load
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Solution Overview
Problem
Integrated touch sensors with displays face increased capacitive loads, affecting performance, response time, power consumption, and noise handling, especially in self-capacitive modes of operation.
Innovation Solution
A two-layer touch sensor architecture with driven shield signals on electrodes, reducing capacitive loads by configuring the controller to send specific drive signals and shield signals during mutual- and self-capacitive modes, allowing for efficient touch sensing with lower loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If integrated touch sensor with display is used, then touch sensing capability is improved, but capacitive load increases significantly
Solution Approach 1:
The touch sensor is divided into two separate arrays: a first array of capacitive nodes and a second array of capacitive nodes. This segmentation allows the sensor to reduce capacitive load by separating the sensing functions while maintaining full touch sensing capability through their cooperative operation.
2Ease of operation
If self-capacitive mode is used, then simplified control is achieved, but capacitive load increases dramatically
Solution Approach 1:
The controller is configured to operate in self-capacitive mode with the segmented arrays, where only a portion of the first array is driven while the second array remains passive. This segmentation enables simplified control compared to mutual-capacitive mode while dramatically reducing the capacitive load that would otherwise be present in full self-capacitive operation.
3Area of stationary object
If higher capacitive load is tolerated, then larger touch sensor area can be achieved, but response time decreases
Solution Approach 1:
By segmenting the touch sensor into two arrays and using selective driving, the patent achieves large touch sensor area coverage while maintaining fast response times. The segmented architecture reduces the effective capacitive load that limits response speed, allowing large area sensors to respond quickly without requiring higher tolerable capacitance.
4Reliability
If higher capacitive load is accepted, then more comprehensive touch detection is possible, but power consumption increases
Solution Approach 1:
The segmented array architecture allows comprehensive touch detection across the entire sensor area while consuming less power. By selectively activating only portions of the first array during self-capacitive mode and keeping the second array passive, the system achieves thorough touch detection without the high power consumption that would result from driving all electrodes simultaneously.
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 effectively decreases capacitive loads to under 100 pF during self-capacitive modes, improving touch sensor performance, response time, and reducing power consumption while enhancing noise handling.
Implementation Method 1
A touch sensor may detect the presence and position of a touch or the proximity of an object (such as a user's finger or a stylus) within a touch-sensitive area
Data Source
AI summary
A device includes a controller coupled to a touch sensor. The touch sensor includes a first array of capacitive nodes substantially aligned with a second array of capacitive nodes in a mechanical stack. The controller is configured, when in a self-capacitive mode of operation, to send a first drive signal to a plurality of the electrodes of the first array, send a shield signal to at least a portion of the electrodes of the second array at the same time as the first drive signal is sent to the plurality of electrodes of the first array, and sense touch inputs based on signals received from the plurality of electrodes of the first array while the first drive signal is being sent to the plurality of electrodes of the first array and the shield signal is being sent to the at least a portion of the electrodes of the second array.