Capacitive Position Indicator Isolation Circuit
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Solution Overview
Problem
Existing electronic pens for capacitive touch panels face challenges in maintaining high capacitance while having a thin pen point, leading to increased power consumption and unnecessary signal radiation.
Innovation Solution
A position indicator with a conductive casing and an isolation circuit that generates a reference signal with opposite polarity, allowing for high capacitance without power-intensive signal radiation, and preventing signal leakage when not in use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pen point is made thick to increase contact area with the touch panel, then capacitance between the electronic pen and electrodes is increased, but the electronic pen becomes unsuitable for drawing thin lines
Solution Approach 1:
The patent introduces an intermediary mechanism (electrical circuit with oscillation generation and signal radiation) between the thin pen point and the touch panel to enhance capacitance interaction without physically thickening the pen point. The circuit acts as a mediator that amplifies the electrical interaction between the thin pen point and the electrodes.
2Measurement precision
If signal radiation is increased to enhance capacitance detection, then detection sensitivity is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic oscillation to generate signals rather than continuous signal radiation. The oscillation generation circuit creates periodic signals that are radiated through the antenna, reducing average power consumption while maintaining detection sensitivity through the periodic nature of the signal transmission.
3Ease of operation
If the electronic pen is not held by a human, then portability is improved, but unnecessary signal radiation occurs through the casing
Solution Approach 1:
The patent implements a detection mechanism that monitors whether the electronic pen is being held by a human. Based on this feedback, the system automatically activates or deactivates the signal radiation function, preventing unnecessary signal radiation when the pen is not in use while maintaining portability.
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 use as an input pen for capacitive touch panels with a thin pen point, reducing power consumption and minimizing unnecessary signal radiation.
Implementation Method 1
When a finger approaches the touch panel, a capacitance occurs between the finger and an X-electrode and a Y-electrode in the vicinity of the finger
Implementation Method 2
a human body absorbs a current through this capacitance. The amplitude of a signal extracted from the X-electrode is therefore decreased
Implementation Method 3
an isolation circuit having an input terminal and an output terminal insulated from each other; a second low-level side power supply wiring configured to supply a second low-level side power supply potential to the inverting amplifier; a second high-level side power supply wiring configured to supply a second high-level side power supply potential to the inverting amplifier
Data Source
AI summary
A position indicator has a first electrode, an inverting amplifier and electrical isolation circuitry. The first electrode, in operation, receives an input signal from a capacitive touch panel and transmits a reference signal. The inverting amplifier has an input coupled to the first electrode, and, in operation, inverts and amplifies the input signal. The electrical isolation circuitry has an input coupled to an output of the inverting amplifier, and, in operation, generates the reference signal based on the inverted and amplified input signal.