Sensor Driver Frequency Segmentation for Ghost Touch Elimination
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Solution Overview
Problem
Current display devices face challenges in accurately detecting touch inputs due to temperature-related changes in capacitance, leading to false ghost touch detections, especially in varying environmental conditions.
Innovation Solution
The implementation of a sensor driver that transmits alternating driving signals with different frequencies to distinguish between actual touch inputs and temperature-induced changes, using a first frequency sensitive to touch and temperature, and a second frequency insensitive to temperature changes, allowing for accurate determination of touch inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single frequency driving signal is used for touch sensing, then the sensing operation is simple, but temperature changes cause false touch detections reducing reliability
Solution Approach 1:
The sensing operation is segmented into two distinct phases: a first sensing period using a first driving signal frequency that is sensitive to both touch and temperature changes, and a second sensing period using a second driving signal frequency that is insensitive to temperature changes. This segmentation allows the system to separate touch detection from temperature compensation functions, improving reliability while maintaining manageable complexity through structured operational phases.
Solution Approach 2:
The system changes the frequency parameter of the driving signal between two different values. The first frequency is selected to be sensitive to both touch and temperature variations, while the second frequency is selected to be insensitive to temperature changes. By varying this critical parameter, the system can distinguish between actual touch inputs and temperature-induced capacitance changes, thereby resolving the reliability issue.
2Reliability
If alternating driving signals with different frequencies are used, then temperature-induced false detections are reduced, but the sensing operation becomes more complex
Solution Approach 1:
The sensor driver operates in a periodic manner, alternating between the first sensing period with the first driving signal frequency and the second sensing period with the second driving signal frequency. This periodic action structure allows the system to systematically collect data under different frequency conditions, enabling temperature compensation and accurate touch detection while maintaining a regular, manageable operational pattern that doesn't excessively increase complexity.
Solution Approach 2:
The system uses feedback from the second sensing period (which is insensitive to temperature) to compensate for temperature effects observed in the first sensing period. By comparing results from both sensing periods and using the temperature-insensitive data to correct the temperature-sensitive measurements, the system achieves high reliability. This feedback mechanism allows accurate touch detection while keeping the operational complexity manageable through a clear cause-and-effect relationship between the two sensing phases.
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 effectively differentiates between real touch inputs and temperature-related changes, reducing false ghost touch detections and enhancing the accuracy of touch input detection in various environmental conditions.
Implementation Method 1
The first sensing signals may represent capacitances of the sensors. The sensor driver may sense the touch input by comparing the capacitances with reference capacitances of the sensors
Data Source
AI summary
A display device includes a display unit including pixels. A sensor unit overlaps with the display unit and includes sensors. A sensor driver transmits a driving signal to the sensors, and receives sensing signals corresponding to the driving signal from the sensors. One sensing period includes a first sensing period and a second sensing period. The sensor driver transmits a first driving signal having a first frequency to the sensors in the first sensing period, and transmits a second driving signal having a second frequency different from the first frequency to the sensors in the second sensing period.