Touch Panel Electrode Lines for Wireless Stylus Power via Capacitive Coupling
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Solution Overview
Problem
Existing touch panels in smartphones and tablets face challenges in wireless power transfer due to high resistance in electrode lines, which limits capacitive coupling efficiency and increases device thickness and cost with additional power transmission circuits.
Innovation Solution
A touch panel with an electrostatic sensor unit and a power supply unit that applies AC voltage to TX and RX lines to induce capacitive coupling, allowing for wireless power transfer to a stylus pen without the need for additional power transmission circuits, simplifying the circuit structure and reducing device thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a coil of resonance circuit is configured with electrode lines of touch panel for electromagnetic energy transmission, then wireless power transfer is enabled, but high resistance of electrode lines causes energy dissipation as thermal energy and prevents circuit resonance
Solution Approach 1:
The patent changes the operating parameters by applying AC voltage at a frequency lower than the cutoff frequency of the electrode lines. This parameter change allows the electrode lines to function effectively as capacitive coupling elements rather than inductive coils, overcoming their high resistance limitation and enabling efficient wireless power transfer without significant energy dissipation.
2Use of energy by moving object
If an additional power transmission device is disposed under the LCD module for wireless power supply, then power can be supplied to stylus pen, but device thickness increases
Solution Approach 1:
The patent merges the power transmission function with the existing touch panel structure by utilizing the electrode lines of the touch panel as capacitive coupling elements. This integration eliminates the need for separate power transmission devices under the LCD module, thereby maintaining device thickness while enabling wireless power supply to the stylus pen.
Solution Approach 2:
The electrode lines of the touch panel are given dual functionality: they serve both as touch sensing elements and as capacitive coupling elements for wireless power transfer. This multi-functionality eliminates the need for additional dedicated power transmission circuits, reducing device thickness and component count.
3Use of energy by moving object
If an additional circuit panel for supplying power is disposed under the LCD module, then wireless power supply to stylus pen is enabled, but manufacturing cost increases
Solution Approach 1:
The patent combines the power transmission function with the existing touch panel electrode lines, eliminating the need for separate additional circuit panels. This merging approach reduces component count and assembly complexity, thereby lowering manufacturing costs while maintaining the wireless power supply function.
Solution Approach 2:
The existing electrode lines are made multi-functional to serve both touch sensing and wireless power transfer purposes. This eliminates the need for additional dedicated power supply circuits, reducing bill of materials costs and simplifying the manufacturing process.
4Measurement precision
If electrode lines with high resistance are used for capacitive coupling, then touch panel can detect touch position, but wireless power transfer efficiency is significantly reduced
Solution Approach 1:
The patent changes the operational parameters by operating at frequencies below the cutoff frequency of the electrode lines. This parameter change transforms the function of the high-resistance electrode lines from inductive coupling (inefficient for power transfer) to capacitive coupling (effective for both touch detection and power transfer), resolving the contradiction between touch detection accuracy and power transfer efficiency.
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
Enables efficient wireless power transfer to a stylus pen through capacitive coupling, reducing device thickness and cost by eliminating the need for additional power transmission circuits and maintaining resonance for effective energy transfer.
Implementation Method 1
a power supply unit configured to selectively apply an AC voltage to the TX lines and the RX lines to induce capacitive coupling between an external LC circuit and the electrostatic sensor unit
Implementation Method 2
A resonance induction circuit installed at a power transmission side (power transmission device) converts power energy into electromagnetic energy and radiates it as electromagnetic waves into space
Implementation Method 3
A resonance induction circuit installed at a power transmission side (power transmission device) converts power energy into electromagnetic energy and radiates it as electromagnetic waves into space
Implementation Method 4
A power reception side (stylus pen) receives the electromagnetic energy through a resonance induction circuit installed at the power reception side
Implementation Method 5
A power reception side (stylus pen) receives the electromagnetic energy through a resonance induction circuit installed at the power reception side
Data Source
AI summary
A touch panel includes an electrostatic sensor unit in which a plurality of TX lines and RX lines intersect with each other to detect a touch position electrostatically, and a power supply unit configured to selectively apply an AC voltage to the TX lines and the RX lines to induce capacitive coupling between an external LC circuit and the electrostatic sensor unit.