Capacitance Touch Panel Noise Reduction via Dynamic Frequency Adjustment
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Solution Overview
Problem
Conventional capacitance-type touch panels face challenges in minimizing disturbance noise effects, particularly due to fluorescent lamps and AC power sources, which cause malfunctions and require precise sampling times that are difficult to apply uniformly across varying touch gestures.
Innovation Solution
A touch panel device with a driver, touch sensor, receiving processor, optimum frequency generator, and signal generator that processes receiving signals to identify noise frequencies, generates a frequency control signal, and adjusts the transmission signal frequency to minimize noise interference by changing the driving signal frequency until the noise level is below a specific ratio relative to a reference value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If sampling is performed at the rising edge or falling edge of the waveform to cancel noise components, then noise cancellation is achieved, but it becomes difficult to apply exact sampling time to receiving signals due to non-uniform delay caused by varying touch gestures
Solution Approach 1:
The patent measures the delay time between transmission signal and receiving signal in advance during a non-touch period, and stores this delay information for later use during touch operations. This preliminary measurement eliminates the need to perform complex delay calculations in real-time during touch gestures, making the sampling process easier to control while maintaining effective noise cancellation.
2Object-affected harmful factors
If frequency of transmission signal is changed to minimize disturbance noise, then noise effect is reduced, but there is no established method to determine the optimum frequency for noise elimination
Solution Approach 1:
The patent measures the noise level at the current transmission signal frequency, compares it with a reference noise level, and based on this feedback, determines whether to change the frequency. If the current noise level exceeds the reference level by a predetermined threshold, the system changes to a different frequency and re-measures, creating a closed-loop feedback system that automatically optimizes frequency selection without requiring complex pre-calculation or external input.
Solution Approach 2:
The patent changes the transmission signal frequency in discrete steps (e.g., increasing by a fixed frequency increment) rather than continuously scanning all possible frequencies. This partial action approach finds a suitable frequency with minimal changes, avoiding the complexity of exhaustive frequency analysis while still achieving effective noise reduction.
3Object-affected harmful factors
If conventional noise cancellation methods are applied, then some noise components are removed, but the methods cannot effectively handle noise frequencies close to the transmission signal frequency
Solution Approach 1:
The patent dynamically changes the frequency parameter of the transmission signal based on measured noise characteristics. When noise is detected at or near the current transmission frequency, the system adjusts the frequency parameter to a different value, thereby moving the transmission signal away from problematic noise frequencies and maintaining reliable touch signal detection despite the presence of disturbance noise.
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 disturbance noise on touch signal sensitivity and accuracy by dynamically adjusting the transmission signal frequency, preventing malfunctions and improving touch action detection precision.
Implementation Method 1
The transmission electrode and receiving electrode are arranged in a cross bar configuration, and the capacitor characteristic is established by the transmission electrode, the receiving electrode, and the dielectric. When a touch action by a user occurs, capacitance changes, and the changed capacitance is detected through a change in the voltage appearing between the transmission electrode and the receiving electrode.
Implementation Method 2
A noise component may be introduced to the capacitance-type touch panel, due to fluorescent lamps or AC power sources. That is, when a user generates a touch action, the user acts as an antenna, and noise is delivered to the touch panel, causing malfunctions in the touch panel.
Data Source
AI summary
Disclosed are a capacitance-type touch panel device and an operation method for the same. In order that the effect of disturbance noise comprised in a receiving signal is minimized, a calculation for a digital code which has been converted into a digital signal type is performed. Information about the noise level of the digital code is compared to a reference value, and, when the frequency of the noise is determined to be similar to the frequency of the receiving signal, the frequency of an operation signal, which is supplied from a signal generation unit, is changed.