Touch Panel Controller Dynamic Baseline Update
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Solution Overview
Problem
Touch panel sensors face significant touch signal degradation due to environmental noise, such as voltage supply noise and temperature changes, which can lead to inaccurate detection of object position and magnitude on the touch panel.
Innovation Solution
A touch panel controller that dynamically adjusts the drive frequency of the touch panel sensor to minimize noise by capturing signal baseline images at multiple frequencies during production and power-up, and periodically switching to a lower noise frequency when noise levels exceed a threshold, allowing for continuous accurate touch event detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch panel controller uses a fixed drive frequency, then the system operation is simple, but the noise level increases and touch signal accuracy degrades
Solution Approach 1:
The touch panel controller dynamically adjusts the drive frequency based on detected noise levels. When environmental noise is detected, the controller switches from a first drive frequency to a second drive frequency, transforming the static frequency operation into a dynamic adaptive system that optimizes signal detection accuracy under varying environmental conditions
Solution Approach 2:
The controller changes the drive frequency parameter in response to detected noise conditions. By monitoring the touch panel sensor output and identifying noise patterns, the system modifies the drive frequency parameter to minimize noise interference and maintain accurate touch signal detection
2Reliability
If the controller switches drive frequency to minimize noise, then the noise level decreases and detection accuracy improves, but the system complexity and response time increase
Solution Approach 1:
The system pre-determines multiple drive frequencies and their corresponding optimal operating conditions during system initialization or calibration phase. When noise is detected, the controller can immediately switch to a pre-identified suitable frequency without requiring complex real-time analysis, reducing the time penalty of frequency switching
Solution Approach 2:
The controller continuously monitors the touch panel sensor output to detect noise levels and automatically adjusts the drive frequency in response. This closed-loop feedback mechanism ensures that frequency switching occurs only when necessary to maintain detection reliability, minimizing unnecessary switches and associated time losses
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 touch panel controller effectively reduces noise interference, ensuring accurate detection of touch events and maintaining optimal performance even in noisy environments.
Implementation Method 1
Capacitive touch panels are often used with touch screen devices. A capacitive touch panel generally includes an insulator, such as glass, coated with a transparent conductor, such as indium tin oxide (ITO). As the human body is also an electrical conductor, touching the surface of the panel results in a distortion of the panel's electrostatic field, measurable as a change in capacitance.
Data Source
AI summary
A touch panel controller is disclosed herein. The controller includes output circuitry for driving a touch panel sensor and input circuitry for determining when an object performs a touch event over the touch panel sensor. The controller is configured to cause the output circuitry to generate drive signals having a different frequency characteristic when the controller determines noise present within the sensor is above a noise threshold. The controller communicates with a software device driver on a host processor to store signal baseline images for a range of frequencies during production test and power-up. The controller is configured to receive a signal baseline image from the host processor when the controller causes change to a different drive frequency. The controller is configured to cause change to the different drive frequency while the object is still performing the touch event over the touch panel sensor.