Touch Panel Noise Cancellation via Signal Line Switching
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Solution Overview
Problem
Conventional touch panel systems are unable to reliably remove a wide variety of noises, including phantom noise generated by electromagnetic interference, which affects detection sensitivity and accuracy in touch operations.
Innovation Solution
The implementation of a touch panel system with a main sensor and a sub sensor on the same surface, where the sub sensor detects noise signals and a capacitance value distribution detection circuit that switches between different signal line configurations to eliminate electromagnetic noise, allowing for the subtraction of noise from the main sensor's output to extract the touch signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional touch panel system is used, then the device can perform basic touch detection, but noise from the display device and external sources impairs detection sensitivity
Solution Approach 1:
The touch panel is divided into a main sensor region and a sub sensor region. The main sensor detects both touch signals and noise, while the sub sensor detects only noise. This segmentation allows separate processing of touch and noise components to improve detection sensitivity.
Solution Approach 2:
The noise component is extracted from the main sensor output by subtracting the sub sensor output. This extraction process removes noise interference from the touch detection signal, improving measurement precision without sacrificing touch detection capability.
2Reliability
If the sub sensor is added to detect noise signals, then noise cancellation capability is improved, but the device complexity increases
Solution Approach 1:
The main sensor and sub sensor are merged into a unified sensor system with shared signal processing circuitry. The subtraction of sub sensor output from main sensor output is performed through integrated circuit operations, reducing the overall complexity despite adding noise detection capability.
Solution Approach 2:
The sub sensor serves multiple functions: it detects noise signals for cancellation purposes and also contributes to overall system calibration. This multi-functionality justifies the added complexity by providing enhanced noise removal effectiveness across different operating conditions.
3Object-affected harmful factors
If the capacitance value distribution detection circuit switches between different signal line configurations, then electromagnetic noise is eliminated, but the operation complexity increases
Solution Approach 1:
The capacitance value distribution detection circuit performs periodic switching between different signal line configurations during the detection process. This periodic action allows the system to collect data under different conditions and eliminate electromagnetic noise through differential processing, while the automation reduces operational complexity.
Solution Approach 2:
The system uses feedback from the detected capacitance values to automatically adjust and optimize the signal line configuration. This feedback mechanism eliminates the need for manual intervention in signal line switching, reducing operation complexity while maintaining effective electromagnetic noise elimination.
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 cancels a wide range of noises, enhancing detection sensitivity and accuracy for touch operations by isolating and removing noise signals, thereby improving the overall performance of the touch panel system.
Implementation Method 1
a sub sensor (sub sensor section) 32 which is different from the main sensor does not detect a touch operation but detects a noise signal reflected in the touch panel 3
Implementation Method 2
a subtracting section 41 which subtracts an output signal supplied from the sub sensor 32 from an output signal supplied from the main sensor 31 so as to extract a signal derived from a touch operation itself
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
A touch panel system (71a) includes a capacitance value distribution detection circuit (72). The capacitance value distribution detection circuit (72) switches a connection state between a first connection state and a second connection state, which first connection state makes first signal lines (HL1 to HLM) serve as drive lines (DL1 to DLM) and second signal lines (VL1 to VLM) serve as sense lines (SL1 to SLM), and which second connection state makes the second signal lines (VL1 to VLM) serve as the drive lines (DL1 to DLM) and the first signal lines (HL1 to HLM) serve as the sense lines (SL1 to SLM).