Position Indicator Resonance Circuit Switching for Pressure Detection
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Solution Overview
Problem
Conventional position detection methods using electromagnetic induction are prone to errors due to variations in resonance frequency or phase caused by nearby metal objects, environmental factors, and device orientation, leading to incorrect detection of writing pressure.
Innovation Solution
A position indicator with two resonance circuits, one fixed and one variable, that switches between them based on a predetermined signal, allowing the detection apparatus to differentiate between signals and cancel out environmental influences, ensuring accurate writing pressure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single resonance circuit with a variable capacitor is used to detect writing pressure, then the detection method is simple, but the detection accuracy deteriorates due to environmental factors like nearby metal objects causing resonance frequency shifts
Solution Approach 1:
The single resonance circuit is segmented into two separate resonance circuits: a first resonance circuit with a fixed capacitor and a second resonance circuit with a variable capacitor. This segmentation allows the system to differentiate between environmental frequency shifts and actual writing pressure changes, thereby improving measurement precision while maintaining manageable device complexity
Solution Approach 2:
The first resonance circuit acts as an intermediary reference that provides a stable baseline frequency unaffected by writing pressure. By comparing the second resonance circuit's frequency changes against this reference, the system can eliminate environmental interference and accurately detect writing pressure
2Loss of information
If a variable capacitor is used in the resonance circuit to detect writing pressure, then writing pressure information can be obtained, but environmental factors cause false detection of writing pressure
Solution Approach 1:
The system uses feedback by continuously monitoring both resonance circuits and comparing their outputs. The first resonance circuit provides feedback on environmental conditions, allowing the system to compensate for false detections and maintain reliable writing pressure measurement
Solution Approach 2:
The first resonance circuit serves as an intermediary reference that mediates between environmental interference and the writing pressure detection. By providing a stable reference frequency, it enables the system to distinguish genuine writing pressure signals from environmental noise, thereby improving detection reliability
3Measurement precision
If the resonance circuit is made sensitive to writing pressure, then writing pressure detection is enabled, but the circuit becomes susceptible to resonance point displacement from environmental factors
Solution Approach 1:
The detection function is segmented between two resonance circuits: one dedicated to environmental reference (first circuit with fixed capacitor) and one to writing pressure detection (second circuit with variable capacitor). This segmentation isolates the harmful environmental factors from the measurement process while maintaining sensitivity to writing pressure
Solution Approach 2:
The first resonance circuit acts as an intermediary that absorbs and reports environmental effects. By comparing the second circuit's changes against this intermediary reference, the system can eliminate harmful environmental factors while preserving writing pressure detection capability
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 enables accurate detection of writing pressure while minimizing the impact of environmental factors and device orientation, ensuring compatibility with both conventional and novel position detection systems.
Implementation Method 1
a resonance circuit configured to establish electromagnetic coupling with a conductor of a sensor of a position detection apparatus
Implementation Method 2
a resonance circuit configured from at least an inductance element and a capacitance element... a second resonance circuit including the inductor, the capacitor, and a variation device configured to vary a resonance frequency or a phase
Data Source
AI summary
A position indicator includes a first resonance circuit including an inductor and a capacitor, a second resonance circuit including the first resonance circuit and a variation device configured to vary a resonance frequency or a phase of the second resonance circuit in response to an act of a user, and a switch circuit configured to perform changeover between the first resonance circuit and the second resonance circuit. The switch circuit is changed over such that, when no signal is received from outside of the position indicator and when a signal other than a predetermined signal is received from outside of the position indicator, the second resonance circuit is selected, and when the predetermined signal is received from outside of the position indicator, the first resonance circuit is selected, and the selected resonance circuit is configured to electromagnetically couple with a conductor of a sensor of the position detection apparatus.