In-Cell Touch Display Compensation Circuit for Noise Interference
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Solution Overview
Problem
In-cell touch screens suffer from significant noise interference due to parasitic capacitance between the touch layer and the common electrode layer, leading to distorted sensing signals and reduced signal-to-noise ratios, and the addition of shielding layers can reduce panel transparency and cause moire patterns.
Innovation Solution
A compensation circuit comprising a capacitor, operational amplifier, and resistors is used to filter out voltage fluctuations from the common electrode layer, providing a compensated sensing signal to the touch chip, thereby improving the signal-to-noise ratio and reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shielding layer is added between the touch layer and the driving layer, then noise interference is reduced, but panel transparency is reduced and moire patterns occur
Solution Approach 1:
The harmful function of the common electrode layer (generating voltage fluctuations that interfere with touch signals) is extracted and separated from the touch sensing path. The compensation circuit extracts only the necessary drive signals while filtering out the harmful voltage fluctuations, allowing the common electrode layer to remain without requiring an additional shielding layer that would block light.
Solution Approach 2:
The compensation circuit acts as an intermediary between the common electrode layer and the touch layer. It processes the drive signals to remove voltage fluctuations before they can interfere with the touch sensing signals, thereby reducing noise interference without requiring a physical shielding layer that would compromise panel transparency.
2Length of stationary object
If the touch layer is placed close to the common electrode layer to reduce thickness, then display screen thickness is reduced, but noise interference increases due to parasitic capacitance
Solution Approach 1:
The compensation circuit converts the harmful voltage fluctuations generated by the common electrode layer into useful compensation signals. By detecting and processing these fluctuations, the circuit generates compensation signals that cancel out the noise interference, allowing the touch layer to remain close to the common electrode layer without sacrificing thickness benefits.
Solution Approach 2:
The compensation circuit implements a feedback mechanism where voltage fluctuations from the common electrode layer are detected and fed back through the compensation circuitry. This feedback loop generates compensating signals that are applied to the touch layer, actively canceling out the noise interference and maintaining signal quality despite the close proximity of the layers.
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 compensation circuit effectively filters out noise interference, retaining the real touch sensing signal and enhancing the anti-interference ability of the touch screen, thereby improving the signal-to-noise ratio and maintaining display quality.
Implementation Method 1
A first electrode plate of the capacitor is connected to the compensation signal line. One end of the first resistor is connected to a second electrode plate of the capacitor.
Implementation Method 2
An inverting input terminal of the operational amplifier is connected to another end of the first resistor, and an output terminal of the operational amplifier is connected to the touch chip.
Data Source
AI summary
A touch display and an anti-interference method thereof are provided. The touch display has a display panel, a touch panel, a touch chip, and a compensation circuit. A compensation signal line is led out from a common electrode layer of the display panel. A sensing signal line is led out from a touch layer of the touch panel. An input terminal of the compensation circuit is connected to the compensation signal line and the sensing signal line, and a compensated sensing signal is output to the touch chip from the output terminal. An ability of the touch screen to resist noise interference is improved.