Capacitance Touch Panel Using Polarity Alternation for Noise Reduction
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Solution Overview
Problem
Capacitance-type touch panels face challenges in distinguishing touch signals from disturbance noise, leading to malfunctions due to noise interference, and existing solutions either require complex circuit configurations or risk removing touch signals along with noise.
Innovation Solution
A capacitance-type touch panel with a drive control circuit, strip-shaped drive electrodes, and touch detection electrodes that produce a polarity-alternating detection signal due to external proximity, allowing for secure touch detection while minimizing noise influence and circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple drive signals with different frequencies are used to distinguish touch signals from disturbance noise, then noise resistance is improved, but detection time increases and circuit complexity increases
Solution Approach 1:
The patent applies periodic action by using a single drive signal with alternating polarity (positive and negative phases) instead of multiple different frequency signals. The touch detection is performed periodically during the positive phase and negative phase, allowing the system to distinguish touch signals from disturbance noise through the periodic polarity alternation while maintaining fast detection speed and simple circuitry.
Solution Approach 2:
The patent changes the parameter of drive signal polarity rather than using multiple different frequencies. By alternating the polarity of a single drive signal between positive and negative phases, the system achieves noise resistance equivalent to using multiple frequencies but with simpler circuit implementation and faster detection, as no frequency switching or complex signal preparation is required.
2Reliability
If multiple drive signals with different frequencies are used to distinguish touch signals from disturbance noise, then noise resistance is improved, but device complexity increases
Solution Approach 1:
The patent uses periodic polarity alternation of a single drive signal instead of generating and switching between multiple different frequency signals. This periodic action during positive and negative phases enables the detection circuit to distinguish touch signals from disturbance noise while keeping the circuit configuration simple, as no additional signal generators or complex switching mechanisms are needed.
Solution Approach 2:
The patent changes the polarity parameter of a single drive signal rather than using multiple frequency parameters. This approach simplifies the device complexity by eliminating the need for multiple signal sources and frequency switching circuits, while still achieving effective noise resistance through the alternating positive and negative phase detection.
3Reliability
If a low-pass filter is used to remove disturbance noise, then noise resistance is improved, but touch signals may be removed along with noise
Solution Approach 1:
The patent uses periodic polarity alternation to distinguish touch signals from noise without using a low-pass filter. During the positive phase, the detection circuit samples the signal, and during the negative phase, it samples again. By comparing the results from both phases, the system can identify and remove disturbance noise while preserving the touch signal, which appears consistently across both phases, thus avoiding the signal loss problem associated with low-pass filtering.
Solution Approach 2:
The patent converts the potentially harmful effect of disturbance noise into a beneficial differentiation mechanism. By using alternating polarity drive signals, the system causes disturbance noise to manifest differently during positive and negative phases, while the genuine touch signal remains consistent. This allows the detection circuit to identify and eliminate noise while preserving the touch signal, effectively converting the noise problem into a useful discrimination tool without requiring aggressive filtering that would remove valid touch signals.
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 solution enables secure detection of touch signals while reducing noise interference and detection time, with a simplified circuit configuration that effectively separates touch components from noise components.
Implementation Method 1
capacitance is formed in each intersecting part, and each outputs a detection signal in synchronization with the drive signal
Implementation Method 2
the detection signal comes to be a polarity-alternating signal including a positive-negative asymmetrical signal component which is due to presence of the external proximity object
Data Source
AI summary
A capacitance-type touch panel, allowing disturbance noise and touch detection time to be reduced and having a simple configuration, is provided. The capacitance-type touch panel including: a plurality of drive electrodes each having a strip shape; a drive control circuit performing control such that a drive signal for touch detection is selectively applied to the drive electrodes; a plurality of touch detection electrodes arranged to intersect with the drive electrodes in such a manner that capacitance is formed in each intersecting part, and each outputting a detection signal in synchronization with the drive signal; and a detection circuit detecting an external proximity object based on the detection signal. The drive control circuit controls application of the drive signal in such a manner that the detection signal is a polarity-alternating signal including a positive-negative asymmetrical signal component which is due to presence of the external proximity object.