Touch Display Crosstalk Compensation via Gate Voltage Modulation
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Solution Overview
Problem
Touch sensitive devices face challenges in effectively reducing or eliminating crosstalk between display and touch components, which interferes with accurate touch and hover event recognition.
Innovation Solution
The solution involves adjusting gate voltages in thin film transistors (TFTs) to reduce parasitic capacitances causing crosstalk, either by scanning at multiple low voltage levels to determine and compensate for crosstalk components or by modulating the gate voltage to push out-of-band crosstalk components during the touch mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gate voltages are reduced to reduce parasitic capacitances, then crosstalk is reduced, but display quality may deteriorate
Solution Approach 1:
The patent applies dynamics by making the gate voltage adjustable and time-dependent. During touch mode, the gate voltage is dynamically reduced to minimize parasitic capacitance and crosstalk. During display mode, the gate voltage returns to normal levels to maintain display quality. This dynamic adjustment resolves the contradiction by allowing the system to optimize for crosstalk reduction when needed while preserving display performance when not in touch mode.
Solution Approach 2:
The patent changes the electrical parameter (gate voltage) of the TFTs based on operational mode. By modifying the gate voltage parameter from its standard display level to a reduced level during touch sensing, the system reduces parasitic capacitance and crosstalk. This parameter change enables the system to achieve low crosstalk during touch operations without permanently compromising display quality.
2Object-affected harmful factors
If gate voltage is modulated to push crosstalk out-of-band, then crosstalk is reduced, but energy consumption increases
Solution Approach 1:
The patent employs periodic action by modulating the gate voltage at a specific frequency during touch mode. This periodic modulation pushes the crosstalk signal out-of-band, separating it from the touch sensing frequency band. The modulation is applied only during touch operations, not continuously, which limits the additional energy consumption to only when needed for touch sensing.
Solution Approach 2:
The patent converts the harmful crosstalk signal into a beneficial separation by modulating it out-of-band. The modulation frequency is chosen such that the crosstalk appears at a different frequency than the touch sensing signal, allowing easy filtering and recovery of the true touch signal. This transforms the crosstalk from a harmful interference into a separable component that can be easily removed.
3Measurement precision
If multiple scans are performed at different gate voltage levels, then crosstalk compensation accuracy is improved, but processing time increases
Solution Approach 1:
The patent applies preliminary action by performing multiple scans at different gate voltage levels to characterize and determine the crosstalk components before actual touch sensing operations. The system pre-determines the crosstalk characteristics and stores compensation data, which is then applied during normal touch operations. This preliminary characterization reduces the time required during actual touch sensing, as the compensation algorithm is already prepared.
Solution Approach 2:
The patent uses feedback by comparing the results from multiple scans at different gate voltage levels to determine the crosstalk components. The system analyzes the differences between scans to calculate compensation values, which are then fed back into the touch sensing algorithm. This feedback mechanism enables accurate crosstalk compensation while optimizing the number of scans needed to achieve sufficient precision.
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 improves touch and hover sensing accuracy by reducing crosstalk, resulting in clearer and more reliable touch and hover events for processing in touch sensitive displays.
Implementation Method 1
some display components, such as thin film transistors (TFTs), can introduce crosstalk that can interfere with touch signals
Implementation Method 2
the gate voltage can be modulated during a scan of the active area to push at least a portion of the crosstalk component out-of-band
Data Source
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AI summary
A touch sensitive display capable of compensating for crosstalk in the display is disclosed. Crosstalk in display components can be reduced, eliminated, or otherwise compensated for by reducing or eliminating parasitic capacitances that cause the crosstalk. To do so, gate voltages to the display components, such as thin film transistors (TFTs), that introduce the parasitic capacitances can be reduced or otherwise adjusted. In one approach, the gate voltage can be set at multiple different low levels to generate respective sets of touch signals having different amounts of crosstalk. The different crosstalk amounts can then be used to determine and compensate for the crosstalk in the touch signals. In another approach, gate voltage can be modulated between multiple different low levels to push crosstalk out of band with the generated touch signals. The out-of-band crosstalk can then be used to compensate for the crosstalk in the touch signals.