EMR Stylus Pen Pressure Detection via Capacitance Variation
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Solution Overview
Problem
Existing stylus pens face challenges in producing a sufficient output signal, recognizing precise touches, and detecting pen pressure, while also being cost-effective and compatible with miniaturized touch input devices.
Innovation Solution
A pen and touch input system comprising a touch input device with a sensor unit and control unit, and a stylus pen featuring a ferrite core, coil, and capacitor structure that varies capacitance or inductance based on pressure applied, allowing for improved signal transmission and pressure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EMR method is used for passive stylus pen, then writing and drawing quality is improved, but device thickness increases and manufacturing cost increases
Solution Approach 1:
The patent combines the EMR sensor functionality with the existing capacitance touch panel by integrating EMR sensor patterns into the touch sensor structure. The EMR sensor unit shares the same substrate and conductive layers with the capacitance touch sensor, eliminating the need for a separate EMR sensor panel and reducing overall device thickness while maintaining precise touch recognition capability
Solution Approach 2:
The touch sensor panel is designed to serve multiple functions simultaneously: it acts as both a capacitance touch sensor for general touch input and an EMR sensor for precise stylus recognition. The conductive patterns and electrodes are configured to detect both capacitive touch signals and electromagnetic resonance signals from the stylus, making the single panel universally functional for different input methods
2Measurement precision
If EMR method is used for passive stylus pen, then writing and drawing quality is improved, but manufacturing cost increases
Solution Approach 1:
The patent integrates EMR sensor patterns into the existing capacitance touch panel structure, allowing simultaneous production of both capacitance touch and EMR sensing capabilities in a single manufacturing process. This eliminates the need for separate EMR sensor panels and driving ICs, reducing material costs and assembly complexity while maintaining precise stylus recognition
Solution Approach 2:
The touch controller IC is designed to handle both capacitance touch signals and EMR resonance signals through unified signal processing pathways. The same conductive patterns and electrodes serve dual purposes for different input methods, reducing the need for additional specialized components and lowering overall manufacturing cost
3Power
If resonance frequency is matched for stylus pen, then signal transmission is improved, but signal attenuation increases
Solution Approach 1:
The patent implements dynamic frequency adjustment where the touch controller IC continuously monitors and adapts the driving signal frequency to match the resonance frequency of the stylus pen. This dynamic tuning optimizes signal transmission strength while minimizing energy loss through resonance enhancement at the optimal frequency point
Solution Approach 2:
The system employs feedback mechanisms where the touch controller IC receives resonance signals from the stylus pen and adjusts the driving signal parameters accordingly. The feedback loop monitors signal strength and attenuation, automatically optimizing the resonance frequency match to maximize transmission efficiency and minimize energy loss in real-time
4Measurement precision
If pressure sensor is added to stylus pen, then pen pressure detection is improved, but device complexity and cost increase
Solution Approach 1:
The patent enables the stylus pen to detect pressure through its own resonance characteristics without requiring separate pressure sensors. The resonance frequency and amplitude of the stylus pen naturally vary with applied pressure, and the touch controller IC measures these variations to determine pressure levels, allowing the stylus to self-diagnose its state using its inherent electromagnetic properties
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 system generates a sufficient output signal, detects precise touches, and measures pen pressure with a simple structure, while being cost-effective and compatible with larger screen sizes, reducing signal attenuation, and enabling miniaturization.
Implementation Method 1
a resonance signal is required to have a great amplitude to more accurately distinguish a touch caused by the stylus pen. Thus, a driving signal transmitted to the stylus pen needs to have the almost same resonance frequency as that of the resonance circuit contained in the stylus pen
Implementation Method 2
In case of an electro-magnetic resonance (EMR) pen among the passive stylus pens, a digitizer transmits an electromagnetic signal to the pen and then receives a resonance signal from the pen
Implementation Method 3
an inductor unit comprising a ferrite core disposed in the body unit and a coil wound in multiple layers around at least a portion of the ferrite core
Implementation Method 4
an inductor unit comprising a ferrite core disposed in the body unit and a coil wound in multiple layers around at least a portion of the ferrite core
Implementation Method 5
a capacitor unit disposed in the body unit and comprising a capacitor electrically connected to the coil of the inductor unit... a capacitance of the capacitor unit is varied by the pressure applied to the one end of the core
Data Source
AI summary
A pen and touch input system according to an embodiment of the present invention includes a touch input device including a sensor unit and a control unit that controls the sensor unit, and a stylus pen capable of operating with the touch input device.