Touch Panel Electrode Signaling With Frequency-Phase Offsets
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Solution Overview
Problem
Capacitive touch panels face limitations in accurate touch location detection due to the limited number of available detection signal frequencies, which are constrained by the intrinsic frequency response of large panels, bulk capacitance, and resistance, leading to reduced operable bandwidth and signal-to-noise ratio.
Innovation Solution
The use of detection signals with unique frequency-phase offset combinations, allowing for touch location detection through sensing changes in mutual capacitance at crosspoints using multiple frequency and phase offset signals, reducing the required frequency bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple detection signal frequencies are used to improve touch location detection accuracy, then measurement precision is improved, but device complexity and loss of energy increase due to the constrained operable bandwidth and reduced signal-to-noise ratio in large panels
Solution Approach 1:
The patent introduces a new dimension for signal differentiation by combining frequency with phase offset. Instead of relying solely on multiple frequencies, the system uses unique frequency-phase offset combinations where each electrode is driven with a specific phase offset (e.g., 0°, 120°, 240°) at a given frequency. This dimensional extension allows the system to maintain measurement precision while reducing the number of frequency bands required, thereby simplifying device complexity and energy management.
2Measurement precision
If the number of detection signal frequencies is increased to enhance signal quality, then measurement precision is improved, but loss of energy increases due to reduced operable bandwidth in large panels
Solution Approach 1:
The patent changes the parameters of the detection signals by introducing phase offset as an additional variable. Instead of increasing the number of frequencies to improve signal quality, the system maintains a limited number of frequencies and differentiates signals through unique phase offset combinations. This parameter change allows the system to enhance measurement precision while operating within a constrained frequency bandwidth, thereby reducing energy loss that would otherwise result from managing multiple frequency bands in large panels with reduced operable bandwidth.
3Reliability
If multiple frequency bands are used to improve touch detection robustness, then measurement precision is improved, but device complexity increases due to limited available frequencies constrained by bulk capacitance and resistance
Solution Approach 1:
The patent extends the signal differentiation space by combining frequency with phase offset dimensions. Each electrode is assigned a unique frequency-phase offset combination, such as different phase offsets (0°, 120°, 240°) at a given frequency. This approach enhances detection robustness by providing unique signal signatures for each electrode without requiring multiple frequency bands, thereby avoiding the device complexity and frequency band management challenges that arise from using multiple frequencies in panels constrained by bulk capacitance and resistance.
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 enables accurate touch location detection on large panels by minimizing the number of frequencies needed, improving signal quality and reducing noise, thereby enhancing detection accuracy and robustness.
Implementation Method 1
capacitive touch panels utilized internal electrodes for providing an indication of a touch location on the panel based on detection signals provided and sensed on the electrodes of a touch panel
Implementation Method 2
carrier modulated OFDM signals are used to excite the touch screen and determine touch locations
Data Source
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AI summary
A touch panel system that includes drivers for providing detection signals on a first plurality of electrodes of a touch panel where each detection signal includes one or more frequency signal components with each frequency signal component having a frequency and at least three phase offsets for at least one frequency of the frequency signal components. Each detection signal has a unique frequency-phase offset combination of the one or more frequency signal components. The unique combinations allow for the determination of a touch at specific locations on the panel by sensing signals on a second set of electrodes.