Keyboard Key Position Detection Using Coil Frequency Response
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Solution Overview
Problem
Existing instrument playing apparatuses face challenges in accurately detecting slight displacements of movable members, such as keys, due to limited changes in current flow through coils, resulting in imprecise detection signals.
Innovation Solution
Incorporating a detection system with a magnetic or conductive adjustment weight and a filter that includes a coil, where the frequency response changes based on the distance between the detection part and the coil, allowing for a more accurate detection signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coil and metal plate configuration is used to detect key position, then the structure is simple, but the measurement precision is insufficient for slight displacements
Solution Approach 1:
The patent changes the parameter of frequency response in the detection circuit to amplify slight displacement signals. By adjusting the frequency response characteristic of the circuit including the coil, the system can detect small changes in metal plate position that would otherwise be imperceptible, thereby improving measurement precision without adding complex hardware
Solution Approach 2:
The patent replaces direct mechanical measurement methods with an electromagnetic detection system. Instead of using mechanical sensors or direct contact measurement, the system uses a coil to detect changes in magnetic field caused by metal plate displacement, converting mechanical displacement into electrical signal changes that can be precisely measured
2Device complexity
If the detection part is separated from the adjustment weight, then the detection function is independent, but the device complexity increases
Solution Approach 1:
The patent makes the adjustment weight serve multiple functions: it acts as both the touch feel adjustment component and the detection part (metal plate). By giving the adjustment weight dual functionality, the system reduces the number of separate components while ensuring reliable operation of both adjustment and detection functions through a single integrated element
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 the generation of detection signals that accurately represent slight displacements of movable members, enhancing the precision of key position detection and simplifying the instrument's configuration by using the adjustment weight as both a touch feel adjuster and detection part.
Implementation Method 1
a filter that includes a coil and is configured to generate a detection signal from a reference signal, the filter having a frequency response that changes depending on a distance between the detection part and the coil
Data Source
AI summary
An instrument playing apparatus has: a movable member configured to be displaced responsive to a playing operation of a user; a detection part formed from a magnetic or conductive body and disposed on the movable member; and a filter that includes a coil. The filter has a frequency response that changes depending on a distance between the detection part and the coil, and generates a detection signal from a reference signal.