Display Touch Electrode Parasitic Capacitance Reduction
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Solution Overview
Problem
The self-capacitance detecting method in display apparatuses with touch detection functions is hindered by parasitic capacitance, which increases the load on drive electrodes, particularly due to the intersection of self-capacitance detection wires and connection wires.
Innovation Solution
The display apparatus incorporates a configuration where self-capacitance detection wires intersect connection wires in a manner that allows them to be floated in potential, with switching elements ensuring the same potential for both, reducing parasitic capacitance by amplifying video signal lines in the same phase as drive electrodes, thus minimizing the load during driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-capacitance detection wires and connection wires are arranged in a conventional layout, then the display apparatus can function normally, but parasitic capacitance increases the load on drive electrodes
Solution Approach 1:
The connection wire is configured to have the same potential as the self-capacitance detection wire at their intersection point. This is achieved by connecting the connection wire to the same potential source (Vcom or ground) as the detection wire, eliminating potential difference and thus reducing parasitic capacitance effects between the intersecting wires.
Solution Approach 2:
The patent changes the electrical parameter (potential) of the connection wire at the intersection region to match the detection wire's potential. This parameter change transforms the connection wire from a potential source that would create parasitic capacitance to an equipotential structure that minimizes capacitive coupling.
2Device complexity
If drive electrodes are used for both driving and self-capacitance detection, then device structure is simplified, but parasitic capacitance from wire intersections becomes a significant load
Solution Approach 1:
By making the connection wire equipotential with the detection wire at intersection points, the patent eliminates the voltage difference that would otherwise create parasitic capacitance. This reduces the capacitive load on the drive electrode, improving the signal-to-noise ratio for capacitance detection.
Solution Approach 2:
The patent converts the potentially harmful parasitic capacitance effect into a beneficial low-capacitance configuration by using the same potential for both wires. The intersection, which would normally create unwanted capacitance, is transformed into a low-impedance path that minimizes detection errors.
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 configuration effectively reduces parasitic capacitance, enhancing the accuracy and efficiency of touch detection by minimizing erroneous signals and load on drive electrodes during self-capacitance detection.
Implementation Method 1
a parasitic capacitance produced by the intersection becomes a load during driving of the driving electrode based on the self-capacitance detecting method
Implementation Method 2
a so-called self-capacitance detecting method which is a method for detection using change in a ground capacitance of a detection electrode due to approach or contact of an object
Data Source
AI summary
A display apparatus which can reduce a parasitic capacitance during driving of driving electrodes based on a self-capacitance detecting method is provided. The display apparatus includes: a plurality of connection wires which are formed in a peripheral area and are connected to a plurality of corresponding video signal lines; a video signal line selection circuit which is connected with a plurality of connection wires, selects at least one connection wire and supplies a signal to the video signal lines; self-capacitance detection wires which extend in a direction intersecting an extension direction of the connection wires and intersects the connection wires; common wires which electrically connect the self-capacitance detection wires and drive electrodes; and transistors which are provided between the self-capacitance detection wires and the common wires. Further, the self-capacitance detection wires extend between a display area and the video signal line selection circuit in a plan view.