Touch Screen Demodulation Without Signal Synchronization
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Solution Overview
Problem
Existing touch screen devices face inefficiencies in detecting active capacitance stylus contact due to the need for signal synchronization, which requires additional hardware resources and prolongs synchronization time, affecting detection efficiency.
Innovation Solution
A touch screen device with a demodulation unit and amplitude recovery unit that demodulates signals using two orthogonal signals, allowing for accurate amplitude recovery without synchronization with the transmission signal, thereby eliminating the need for additional hardware resources and improving detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase synchronization is performed by comparing demodulation signals of multiple phases with the transmission signal, then the demodulation signal becomes synchronous with the transmission signal, but large numbers of hardware resources are consumed
Solution Approach 1:
The patent changes the fundamental approach from phase synchronization to amplitude-based detection. By using amplitude demodulation that does not require phase alignment between transmission and demodulation signals, the system eliminates the need for complex phase comparison hardware while maintaining reliable stylus detection functionality.
2Device complexity
If phase synchronization is performed by adjusting the phase of the demodulation signal step by step in a time-sharing manner, then the hardware consumption is reduced, but the synchronization time is often long which will affect the detection efficiency
Solution Approach 1:
The patent fundamentally changes the detection parameter from phase-based to amplitude-based detection. This eliminates the time-consuming phase adjustment process entirely, as amplitude demodulation can be performed immediately without requiring the demodulation signal to be synchronous with the transmission signal, thereby significantly improving detection efficiency.
3Device complexity
If the demodulation signal is asynchronous with the transmission signal, then the hardware resources are reduced, but the amplitude recovered after demodulation cannot correctly reflect the signal received by the reception unit
Solution Approach 1:
The patent replaces the phase-synchronization mechanism with an amplitude-demodulation mechanism. By using envelope detection or amplitude demodulation techniques that are inherently insensitive to phase differences, the system can accurately recover the signal amplitude even when the demodulation signal is asynchronous with the transmission signal, maintaining measurement precision without requiring phase alignment.
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 precise detection of active capacitance stylus contact without requiring signal synchronization, reducing hardware consumption and enhancing detection efficiency, allowing for faster and more accurate stylus detection.
Implementation Method 1
the touch screen may be taken as a part of the mutual capacitor... the transmission unit transmits a signal of certain frequency... the amplitude of the received signal is related with the magnitude of the mutual capacitor
Data Source
AI summary
It is provided a touch screen device applied in an electronic information technology area. In the touch screen device supporting an active capacitance stylus, a demodulation unit demodulates a signal received by a reception unit by two orthogonal signals, and then an amplitude recovery unit recovers an amplitude of the signal received by the reception unit, the amplitude of the signal received by the reception unit can be recovered relatively exactly without the need that the demodulation signal must be synchronous with the signal received by the reception unit (or the signal transmitted from the active capacitance stylus), and there is no need to add additional hardware resources for synchronization in the touch screen device of the embodiment of the present invention compared with the existing detection method which needs to perform synchronization of the demodulation signal and the signal transmitted from the active capacitance stylus in the prior art.