Full-Bridge Tip Driver for Active Stylus Signal Amplification
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Solution Overview
Problem
Capacitive styluses face limitations in increasing the TX signal strength without corresponding increases in power consumption, which can drain the battery faster and reduce usage time.
Innovation Solution
A full bridge driver is used to provide an electrical contact on the stylus body, forming a current return path and enlarging the TX signal amplitude without increasing power consumption, by introducing the capacitance of the user's body into the circuit, thereby reducing resistance and allowing more current to flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the TX signal is increased to improve stylus position tracking, then the signal-to-noise ratio is improved, but the power consumption increases and battery life is reduced
Solution Approach 1:
The user's body is introduced as an intermediary element into the circuit through an electrical contact on the stylus body. The body capacitance serves as a mediator that enables signal amplification without requiring additional power from the stylus battery, thereby resolving the contradiction between improving signal quality and maintaining low power consumption
Solution Approach 2:
The circuit configuration is changed from a single-ended to a full-bridge configuration, which fundamentally alters the electrical parameters of the system. This parameter change enables the utilization of body capacitance to amplify the TX signal amplitude without increasing power consumption, thus improving measurement precision while maintaining energy efficiency
2Power
If the battery is designed to supply higher power to increase the TX signal, then the signal amplitude is improved, but the battery drains faster and usage time is reduced
Solution Approach 1:
The user's body capacitance is introduced as an intermediary energy storage element that supplements the battery's power capacity. This allows the system to achieve higher TX signal power levels without requiring the battery to supply the full power, thereby extending usage time while improving signal amplitude
Solution Approach 2:
The electrical contact on the stylus body serves multiple functions: it provides a current return path, introduces body capacitance for signal amplification, and enables the full-bridge circuit configuration. This multi-functionality allows the system to achieve higher power output without proportionally increasing battery requirements, thus extending usage time
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 approach enhances the signal-to-noise ratio of the TX signal, enabling better detection of the stylus position on touch screens while reducing power consumption, allowing for extended usage without battery drain.
Implementation Method 1
by introducing the capacitance of the user's body into the circuit, thereby reducing resistance and allowing more current to flow
Data Source
AI summary
A stylus may include an electrode that is positioned on the body of the stylus. The stylus may further include a switch. Furthermore, the switch may be used to provide a capacitance that is coupled to the electrode positioned on the body of the stylus to decrease a resistance to an electrical current through the stylus.