Touch Panel Ground Stabilization via Human Body Capacitance
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Solution Overview
Problem
Signal strength declines when using an active stylus based on capacitive coupling due to unstable circuit ground and signal wraparound through the user's body, especially when not connected to an external ground.
Innovation Solution
A touch panel with a signal transmission circuit, active stylus pointing position detection circuit, and touch detection circuit, along with a coupling control circuit that achieves coupling between a conductor and the touch panel's ground, ensuring the conductor is capacitively coupled with the user's hand, thereby connecting the touch panel's ground to an external ground via the human body, stabilizing the signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a built-in battery is used as power supply, then portability is improved, but signal strength declines due to unstable circuit ground
Solution Approach 1:
The user's body acts as an intermediary to couple the circuit ground to external ground. When the user touches the touch panel with their hand, their body provides a capacitive coupling path to external ground, stabilizing the circuit ground potential without requiring a direct physical ground connection.
Solution Approach 2:
The patent replaces the mechanical/electrical direct ground connection system with a capacitive coupling system through the user's body. Instead of requiring a physical ground wire connection, the system uses the user's body capacitance to achieve ground stabilization, enabling wireless operation while maintaining signal integrity.
2Ease of operation
If wireless capacitive coupling is used, then ease of operation is improved, but signal wraparound through user's body causes signal strength decline
Solution Approach 1:
The patent converts the harmful effect of the user's body causing signal wraparound into a beneficial effect. The same user body that causes signal leakage is utilized to provide capacitive coupling to external ground, stabilizing the circuit ground and improving signal transmission reliability.
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 maintains strong signal coupling with the human hand, reducing signal strength decline and inversion, ensuring reliable signal transmission to the active stylus even without an external ground connection.
Implementation Method 1
a position detection device send a signal to an electronic pen such that the electronic pen suits the position detection device... signals from the position detection sensor are transferred to the capacitively coupled active stylus
Implementation Method 2
achieves coupling between a conductor and a ground of the touch panel in accordance with a touch detection result... The conductor is arranged in the touch panel and is capacitively coupled with the user's hand whose touch was detected
Data Source
AI summary
A touch panel has a plurality of conductors arranged for a position detection area and can detect a position pointed to by an active stylus held by a user and a manual touch by the user holding the active stylus. The touch panel includes: a signal transmission circuit that transmits, by capacitive coupling, a signal to the active stylus that can receive the signal transmitted from the touch panel by capacitive coupling with the touch panel; an active stylus pointing position detection circuit that detects the position pointed to by the active stylus by capacitive coupling with the active stylus; a touch detection circuit that detects the manual touch by the user; and a coupling control circuit that performs coupling control to couple one or more of the plurality of conductors and a ground of the touch panel in accordance with a touch detection result of the touch detection circuit.