Auxiliary Capacitor Touch Detection for Noise Reduction
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Solution Overview
Problem
Conventional capacitive touch screen panels face challenges in detecting touch signals due to noise interference from common electrodes and parasitic capacitances, especially when integrated into display devices like LCDs, leading to increased costs and manufacturing complexities.
Innovation Solution
A capacitive touch detection device and method that utilizes an auxiliary capacitor connected to a touch detection sensor, applying a driving voltage to detect voltage differences caused by touch capacitance, minimizing noise interference and enabling stable touch signal acquisition by differentiating between touch and non-touch voltage states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive touch detection is used in display devices, then touch detection function is achieved, but noise interference from common electrodes and parasitic capacitances degrades detection accuracy
Solution Approach 1:
The patent introduces an auxiliary capacitor as an intermediary component connected between the sensor electrode and the common electrode. This auxiliary capacitor acts as a mediator that isolates the touch detection circuit from the noisy common electrode, allowing capacitance measurement while blocking noise transmission. The auxiliary capacitor enables the system to measure touch-induced capacitance changes without directly exposing the detection circuit to the common electrode's electrical noise and parasitic capacitance.
Solution Approach 2:
The patent segments the traditional capacitive touch detection circuit by separating the sensor electrode from the common electrode through the auxiliary capacitor. This segmentation divides the measurement function from the noise source, allowing independent optimization of each component. The sensor electrode focuses on detecting touch capacitance while the auxiliary capacitor handles the isolation function, effectively reducing noise interference in the detection path.
2Measurement precision
If auxiliary capacitor is introduced to reduce noise, then touch signal detection accuracy is improved, but device complexity increases
Solution Approach 1:
The auxiliary capacitor serves multiple functions simultaneously: it acts as a coupling capacitor for AC signal transmission, provides noise isolation from the common electrode, enables DC blocking to eliminate parasitic capacitance effects, and facilitates capacitance measurement. By consolidating these multiple functions into a single component, the patent avoids the need for separate circuits for each function, thereby limiting the increase in overall device complexity while achieving improved measurement precision.
3Reliability
If voltage difference detection method is used, then noise resistance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The voltage difference detection method utilizes the inherent electrical characteristics of the auxiliary capacitor and the touch-induced capacitance changes to automatically generate detectable voltage differences. When a touch occurs, it changes the capacitance value, which naturally produces a voltage difference across the auxiliary capacitor that can be detected. This self-service mechanism reduces the need for complex external calibration and control circuits, as the system uses its own operational parameters to generate the detection signal.
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 allows for reliable touch signal detection with reduced noise interference, enabling the integration of capacitive touch screens into display devices while simplifying manufacturing and improving touch resolution and accuracy.
Implementation Method 1
an auxiliary capacitor (Caux) whose one end is connected to the sensor pattern (10) and to the other end of which a driving voltage is applied for detection of a touch input
Implementation Method 2
a touch detection sensor (14) that is connected to the sensor pattern (10), and that detects a voltage difference that is a difference in the magnitude of a voltage generated in the sensor pattern (10) by a driving voltage applied to the auxiliary capacitor (Caux)
Data Source
AI summary
Provided is a new capacitive touch detection device, detection method, and touch screen panel for detecting a touch signal by detecting a voltage difference of a sensor pattern from a driving voltage applied by an auxiliary capacitor, and to a display device having a built-in capacitive touch screen. A capacitive touch detection device includes: a sensor pattern (10) forming a touch capacitance (Ct) in between a touch input device and the sensor pattern; an auxiliary capacitor (Caux) connected on one side to the sensor pattern (10) and having a driving voltage for touch detection applied to the other side thereof; a charging unit (12) for providing pre-charge signals to the touch capacitance (Ct) and the auxiliary capacitor (Caux); and a touch detection sensor (14) which is connected to the sensor pattern (10) and which detects a touch signal by detecting a voltage difference in the sensor pattern (10) when the touch capacitance (Ct) is added to the auxiliary capacitor (Caux) according to a touch of a touch input instrument. Effects of parasitic capacitance generated due to noise, coupling phenomena and other factors are minimized, to thus stably acquire touch signals.