Resonant Coil Key Displacement Sensing With Drift Compensation
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Solution Overview
Problem
Existing displacement detection technologies for movable members, such as musical keyboard keys, rely on delicate optical elements that are susceptible to shock, vibration, and contamination, leading to unreliable long-term performance.
Innovation Solution
A displacement detection apparatus using first and second resonant circuits with planar coils and capacitors to detect key displacement, employing normalization and equivalent circuits to compensate for variations due to factors like heat and aging, ensuring accurate and reliable detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If delicate optical elements (e.g., grayscale) are used to detect key displacement, then measurement precision is improved, but reliability deteriorates due to sensitivity to shock, vibration, and contamination
Solution Approach 1:
The patent replaces delicate optical elements with a magnetic field-based detection system using resonant circuits. A first resonant circuit is coupled to the movable key and a second resonant circuit is fixed, forming a magnetic coupling system that detects key displacement through changes in resonant frequency and impedance, eliminating vulnerability to shock, vibration, and contamination while maintaining high measurement precision
Solution Approach 2:
The patent utilizes changes in resonant frequency and impedance parameters of the resonant circuits in response to key displacement. By measuring frequency shifts and impedance variations caused by magnetic coupling changes, the system achieves precise displacement detection with robust, contamination-resistant magnetic field sensing
2Reliability
If resonant circuits are used to detect displacement, then reliability is improved, but device complexity increases due to normalization and equivalent circuit requirements
Solution Approach 1:
The patent introduces equivalent circuits that replicate the electrical characteristics of the resonant circuit system under different key positions. These equivalent circuits enable the controller to calculate normalized displacement values by comparing actual circuit responses against pre-established equivalent circuit models, simplifying the interpretation of complex resonant signal variations
Solution Approach 2:
The system employs normalization processes where the controller continuously monitors resonant frequency and impedance changes, compares them against reference values from equivalent circuits, and calculates corrected displacement measurements. This feedback mechanism compensates for environmental variations and circuit parameter drift, maintaining reliability without requiring overly complex hardware
3Ease of manufacture
If optical elements are used for displacement detection, then ease of manufacture is improved, but object-affected harmful factors increase due to sensitivity to environmental conditions
Solution Approach 1:
The patent substitutes optical detection components with solid-state magnetic field sensing using resonant circuits. This replacement maintains manufacturing feasibility through standard PCB circuit fabrication while eliminating the vulnerability of optical elements to shock, vibration, and contamination, as magnetic field sensing occurs through non-contact inductive coupling
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
The apparatus provides reliable and accurate detection of key displacement and velocity over time, minimizing variations caused by environmental factors, and outputs manipulation information for precise musical performance.
Implementation Method 1
a first resonant circuit (50) close to a second end (123) of each key (12) and a second resonant circuit (60) mounted to the support member (14)
Implementation Method 2
A displacement detection apparatus using first and second resonant circuits with planar coils and capacitors to detect key displacement
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present disclosure provides a manipulation information output apparatus comprising a manipulator, a first resonant circuit that includes a first coil mounted to the manipulator, a second resonant circuit that includes a second coil that generates a magnetic field upon supply of an electric current and is configured to output a detection signal of a voltage level depending on a relative position of the second coil with respect to a position of the first coil, wherein the second coil faces the first coil, a first equivalent circuit equivalent to the second resonant circuit in a case where the second resonant circuit is in a state in which a distance between the first coil and the second coil takes a first value, and a processor configured to correct the detection signal based on a first output signal output from the first equivalent circuit upon the electric current being supplied to the first equivalent circuit, and output, based on the corrected detection signal, manipulation information of the manipulator.