Touch Screen Controller Drive Sense Circuits Cross-Coupling
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Solution Overview
Problem
Current touch screen technologies face challenges in efficiently detecting and distinguishing between desired and undesired touches on large, near bezel-less displays due to increased power requirements and electromagnetic cross-coupling issues with tightly packed electrodes, limiting the size of practical touch screen displays.
Innovation Solution
The implementation of drive sense circuits that utilize low voltage signaling and frequency division to monitor sensor signals from electrodes, reducing power requirements and minimizing cross-coupling interference, allowing for effective touch detection on large displays with minimal bezel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If tightly packed electrodes are used to achieve large display area, then area of display increases, but electromagnetic cross-coupling interference increases
Solution Approach 1:
The display area is divided into multiple independent touch sensing regions, each with its own drive and sense circuits. This segmentation allows independent optimization of each region's electrode packing density while isolating electromagnetic interference to local areas, enabling large overall display area without proportional increase in cross-coupling interference.
Solution Approach 2:
Shielding structures and differential signaling are introduced as intermediary elements between tightly packed electrodes. These intermediaries act as barriers that block or redirect electromagnetic fields, preventing cross-coupling interference while allowing the electrodes to remain closely spaced for large display area.
2Reliability
If more drive sense circuits are added to cover entire screen area, then touch detection coverage improves, but power consumption increases
Solution Approach 1:
Instead of continuously operating all drive sense circuits across the entire screen, the system employs periodic scanning of touch sensing regions. Different regions are activated in alternating time slots, providing comprehensive touch detection coverage while ensuring that only a subset of circuits consumes power at any given moment, thereby reducing overall power consumption.
Solution Approach 2:
The system dynamically activates and deactivates drive sense circuits based on detected touch activity or user interaction patterns. When a touch is detected in a specific region, only the circuits responsible for that region remain active, while others are powered down, optimizing the balance between detection coverage and power consumption.
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 approach enables the creation of large, near bezel-less touch screen displays with reduced power consumption and minimized interference, enabling efficient touch detection and processing across the entire screen area.
Implementation Method 1
monitor sensor signals from electrodes
Implementation Method 2
frequency division to monitor sensor signals
Data Source
AI summary
A touch screen display includes a display, a video graphics processing module, electrodes integrated into at least a portion of the display, and drive-sense circuits coupled to the electrodes. The drive-sense circuits, when enabled and concurrent with the display rendering frames of data into the visible images, detect changes in electrical characteristics of electrodes. At least some drive-sense circuits monitor sensor signals on at least some electrodes. A sensor signal includes a drive signal component and a receive signal component. The at least some drive-sense circuits generate the drive signal components of the sensor signals. The receive signal component is a representation of a change in an electrical characteristic of an electrode of the at least some electrodes when a corresponding drive signal component is applied to the electrode. The change in the electrical characteristic of the electrode is indicative of a proximal touch to the touch screen display.