Capacitive Touch Detection Using Segmented Pads and Alternating Voltage
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Solution Overview
Problem
Capacitive touch screen panels face challenges in detecting touch signals due to parasitic capacitance noise, which degrades sensitivity and makes multi-touch detection difficult, especially when integrated with display devices like LCDs that have common electrodes and parasitic capacitance coupling.
Innovation Solution
A capacitive touch detection system that applies an alternating driving voltage to a sensing equivalent capacitor between a sensing pad and a non-sensing pad, using a three-terminal switching device to charge the touch detection sensor and detect changes in voltage to minimize parasitic capacitance effects and stabilize touch signal acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a capacitive type touch screen panel uses parasitic capacitance coupling for signal transmission, then the panel can be integrated with display devices like LCDs, but parasitic capacitance noise is generated which degrades touch detection sensitivity
Solution Approach 1:
The patent segments the touch detection function by separating sensing pads into sensing pads and non-sensing pads. The sensing pads are connected to touch detectors for touch signal detection, while non-sensing pads are connected to alternating voltage generators for parasitic capacitance compensation. This segmentation allows independent optimization of touch detection sensitivity and parasitic capacitance management.
Solution Approach 2:
The patent introduces non-sensing pads as intermediary elements that form parasitic capacitance with sensing pads. These non-sensing pads act as mediators to compensate for parasitic capacitance noise by providing a reference capacitance value, thereby enabling accurate touch detection despite the presence of parasitic capacitance coupling in the integrated display device.
2Reliability
If a capacitive touch screen panel applies high-frequency alternating voltage to detect touch, then touch signals can be detected, but parasitic capacitance from common electrodes creates noise that degrades detection accuracy
Solution Approach 1:
The patent converts the harmful parasitic capacitance effect into a beneficial compensation mechanism. By intentionally forming parasitic capacitance between non-sensing pads and sensing pads, and by connecting non-sensing pads to alternating voltage generators, the system uses the previously harmful parasitic capacitance to compensate for and eliminate noise from display device common electrodes, thereby improving touch detection accuracy.
Solution Approach 2:
The patent changes the electrical parameters of the touch detection system by applying high-frequency alternating voltages to non-sensing pads through alternating voltage generators. This parameter change allows the system to dynamically compensate for parasitic capacitance effects and common electrode noise, enabling reliable touch signal detection in integrated display devices.
3Ease of manufacture
If a capacitive touch screen panel uses conventional touch detection methods, then simple implementation is possible, but multi-touch and gesture cognition cannot be implemented
Solution Approach 1:
The patent segments the touch detection array into multiple sensing pads and non-sensing pads, allowing independent control and detection at each location. This segmentation enables the system to detect multiple simultaneous touches and recognize gestures by analyzing the pattern of activated sensing pads, thereby achieving multi-touch capability while maintaining a relatively simple implementation structure.
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 reduces the impact of parasitic capacitance, enhancing touch sensitivity and enabling stable multi-touch detection by differentiating between touch and non-touch voltages, thus improving the overall performance of capacitive touch screen panels.
Implementation Method 1
a capacitive type touch detection means and a detection method for applying an alternating driving voltage to one side of a sensing equivalent capacitor formed between a sensing pad and a non-sensing pad and detecting a difference in voltage generated from a touch detector depending on a touch to acquire a touch signal
Data Source
AI summary
Disclosed herein are a capacitive type touch detection means and a detection method using a new scheme, which detects a touch signal using a difference between voltage magnitudes detected by a touch detector according to whether a touch is generated, when an alternating voltage is applied to a line equivalent capacitor formed between a sensing pad which is detecting a touch signal and a non-sensing pad adjacent to the sensing pad. The touch detection means includes: a sensing pad configured to generate the touch capacitance Ct between a sensing pad and the touch input means; an alternating voltage configured to be applied to a line equivalent capacitor Ceq formed between the sensing pad and a non-sensing pad adjacent to the sensing pad; and a touch detector connected to the sensing pad to detect a difference in voltage generated according to whether the touch is generated by the touch input means.