Resonant Stylus Pen Circuit for Noise-Robust Touch Detection
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Solution Overview
Problem
Capacitive resonant stylus pens face challenges in generating sufficient output signals due to noise interference and difficulty in detecting touch positions, especially when in contact with conductive objects like the human body, and existing methods struggle with noise reduction and signal transmission efficiency.
Innovation Solution
The stylus pen incorporates a resonance circuit with a ferrite core, a coil wound in multiple layers, and a capacitor, optimized for reduced noise and enhanced signal sensitivity, allowing for accurate touch position detection even in noisy environments and when used with conductive objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a passive stylus pen uses a resonance circuit to generate signals, then touch position detection is enabled, but noise in similar frequency bands greatly reduces sensing precision
Solution Approach 1:
The patent implements dynamic frequency selection where the controller identifies the resonant frequency of the stylus pen and dynamically adjusts the driving signal frequency to match it. This dynamic adaptation allows the system to operate at optimal frequencies while avoiding fixed frequency noise interference, thereby maintaining high touch detection precision in noisy environments.
Solution Approach 2:
The patent changes the frequency parameter of the driving signal to match the resonant frequency of the stylus pen. By dynamically adjusting this critical parameter, the system maximizes signal strength and detection precision while avoiding frequency bands where noise interference occurs, effectively resolving the contradiction between detection precision and noise susceptibility.
2Ease of operation
If a passive stylus pen touches the touch sensor with a conductive object, then signal transmission occurs, but the touch sensor fails to detect the stylus pen touch depending on conductive object location or touch area
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the resonance signal strength and touch detection results. When detection reliability deteriorates due to conductive object interference, the system adjusts the driving signal frequency to better match the stylus pen's resonant frequency, thereby maintaining reliable detection across various usage scenarios including those with conductive objects.
Solution Approach 2:
The system dynamically adjusts the driving signal frequency based on real-time resonance characteristics detected from the stylus pen. This dynamic frequency matching ensures that the system maintains optimal signal transmission and detection reliability regardless of the presence or position of conductive objects, enhancing overall usability reliability.
3Measurement precision
If amplifiers are provided for each touch electrode to receive sensing signals, then signal reception capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the touch electrodes multi-functional by enabling them to both transmit driving signals and receive sensing signals. This universal functionality eliminates the need for separate amplifiers at each electrode, as the same electrodes perform dual roles, thereby reducing device complexity and manufacturing cost while maintaining signal reception capability through resonance-based signal enhancement.
4Measurement precision
If the stylus pen resonates with a driving signal to generate output signals, then touch sensitivity is improved, but noise in similar frequency bands reduces sensing performance
Solution Approach 1:
The patent dynamically changes the frequency parameter of the driving signal to match the resonant frequency of the stylus pen. This parameter adjustment maximizes the resonance effect and touch sensitivity while allowing the system to operate in frequency bands away from fixed noise sources, thereby maintaining high sensing performance even in noisy environments.
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 enables robust signal output, improved touch sensitivity, and accurate touch position calculation, even in environments with noise similar to the stylus pen's resonance frequency, while reducing energy consumption and manufacturing costs.
Implementation Method 1
The stylus pen generates a signal by resonating with a driving signal applied to the touch sensor
Implementation Method 2
an inductor part including a coil wound in multiple layers on at least a portion of the ferrite core
Implementation Method 3
a capacitor part located in the body portion and electrically connected to the inductor part
Data Source
AI summary
An electronic device according to an embodiment includes: a display panel; a touch electrode layer disposed on the display panel and comprising at least one touch electrode; and a conductive wire disposed on the display panel, disposed on the same layer as the touch electrode layer, and generating a magnetic field signal for driving a stylus pen.