Capacitive Stylus Pen LC Circuit Resonance
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Solution Overview
Problem
Existing mobile terminals face challenges in efficiently transmitting and receiving electrical signals between a stylus pen and a touch panel without the need for a separate power supply or complex circuitry, leading to increased costs and thickness due to the use of induction coils and resistance issues in touch panel electrodes.
Innovation Solution
A capacitive coupling system is implemented, using a stylus pen with an LC circuit and a touch panel with intersecting TX and RX lines, where an AC signal is generated to detect pen pressure and transmit signals through the pen tip, allowing for resonance and increased signal magnitude based on pen tilt, eliminating the need for a separate power supply and simplifying the circuit structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a power transmission device including an induction coil is disposed below the LCD module to supply electric power to the stylus pen, then electric power can be transmitted to the stylus pen, but the thickness and cost of the mobile phone increase
Solution Approach 1:
The patent combines the power transmission function with the existing touch panel structure by using the touch panel electrodes as both touch sensing elements and power transmission coils. The electrode lines are configured to serve dual purposes: detecting touch positions and transmitting electromagnetic energy wirelessly to the stylus pen, thereby eliminating the need for a separate power transmission device below the LCD module.
Solution Approach 2:
The touch panel electrodes are designed to perform multiple functions simultaneously: they act as touch sensing electrodes for detecting user input positions and as transmission coils for wireless power transmission to the stylus pen. This multi-functional design eliminates the need for dedicated separate components, reducing both thickness and cost.
2Use of energy by moving object
If electrode lines of a touch panel are formed of a coil, then power can be transmitted, but resistance causes energy loss as thermal energy before circuit resonance occurs
Solution Approach 1:
The patent optimizes the electrical parameters of the electrode lines, including resistance, inductance, and capacitance values, to minimize energy loss. By carefully selecting and adjusting these parameters, the system achieves efficient power transmission with reduced thermal energy loss and enables circuit resonance to occur more effectively.
Solution Approach 2:
The patent utilizes electromagnetic resonance (analogous to mechanical vibration principles) by tuning the LC circuit formed by the electrode lines and capacitor to resonate at a specific frequency. This resonance condition maximizes energy transfer efficiency and minimizes resistive losses, allowing effective wireless power transmission.
3Use of energy by moving object
If a battery is installed in the stylus pen to supply electric power, then the stylus pen can operate independently, but the complexity and cost of the stylus pen increase
Solution Approach 1:
The stylus pen is designed to harvest electromagnetic energy wirelessly from the touch panel electrodes during normal operation. Instead of requiring an independent battery power supply, the stylus pen self-sustains its operational power needs by receiving energy through the capacitive coupling between its tip and the touch panel electrodes, thereby simplifying its internal circuitry.
4Use of energy by moving object
If a separate power transmission device is used to supply power to the stylus pen, then power can be transmitted, but the cost and device complexity increase
Solution Approach 1:
The patent merges the power transmission function into the existing touch panel structure by configuring the touch panel electrodes to serve as both touch sensing elements and power transmission coils. This integration eliminates the need for separate power transmission devices, reducing overall system complexity and cost.
Solution Approach 2:
The touch panel electrodes are designed to perform multiple functions simultaneously: detecting touch positions and transmitting electromagnetic energy wirelessly to the stylus pen. This multi-functional design eliminates the need for dedicated separate components, simplifying the overall system architecture.
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 solution reduces the thickness and cost of mobile terminals, enhances touch recognition rates, and provides a new user interface by increasing the magnitude of electrical signals transmitted and received, while accurately measuring pen pressure without the need for additional power supply devices or complex circuitry.
Implementation Method 1
configured to detect a touch position by using a change in capacitance of a plurality of touch panel electrodes
Implementation Method 2
transmit and receive an electrical signal to and from the touch panel using capacitive coupling
Implementation Method 3
generate an AC signal to be transmitted to the plurality of touch panel electrodes... capable of increasing a magnitude of an electrical signal transmitted and received using a capacitive coupling scheme
Data Source
AI summary
A mobile terminal having a stylus pen and a touch panel is provided. The mobile terminal includes a touch panel having a plurality of touch panel electrodes, and a stylus pen provided to transmit and receive an electrical signal to and from the touch panel using capacitive coupling, wherein the stylus pen includes a main body, a pen tip formed of a conductor and protruding to outside of the main body to apply a touch to the touch panel, and an LC circuit provided within the main body, configured to include an inductor and a capacitor, and electrically connected to the pen tip to generate capacitive coupling between the LC circuit an the touch panel.