Electronic Music Keyboard Key Position Detection
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Solution Overview
Problem
Current electronic music keyboards are unable to accurately detect the position of each key instantaneously, which is necessary to emulate the sounds of mechanical (pipe organ) and electromechanical (phonic wheel organ) instruments, where sound effects vary with key position.
Innovation Solution
The use of magnetic flux density sensors, such as Hall sensors, under each key to detect the position of the key instantaneously, coupled with a microcontroller to manage the signal lines and convert the voltage into key positions, which are then communicated to a Digital Signal Processor (DSP) for sound signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional switches (conductive rubber bubbles) are used under each key to detect key presses, then the device complexity is reduced and ease of manufacture is improved, but the measurement precision of key position detection deteriorates, making it impossible to accurately detect instantaneous key positions for emulating mechanical and electromechanical instruments
Solution Approach 1:
The patent replaces the mechanical switch system (conductive rubber bubbles pressing contacts on PCB) with a magnetic detection system using Hall sensors. This substitution eliminates mechanical contact while enabling continuous, high-precision measurement of key position through magnetic field detection, directly resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent introduces a magnet as an intermediary element attached to each key, which interacts with the Hall sensor to enable non-contact position detection. This intermediary allows the system to achieve precise position measurement without mechanical contact, solving the contradiction by mediating between the key mechanism and the detection system.
2Measurement precision
If magnetic flux density sensors (Hall sensors) are used under each key to detect key position instantaneously, then the measurement precision of key position is improved, enabling faithful emulation of mechanical and electromechanical instruments, but the device complexity increases due to additional sensors and signal processing requirements
Solution Approach 1:
The patent replaces complex mechanical position detection mechanisms with magnetic field-based Hall sensors, which provide continuous analog position information without mechanical wear or contact. This substitution achieves high measurement precision while the complexity is managed through the simplicity of magnetic field interaction and analog signal output.
Solution Approach 2:
The patent utilizes the change in magnetic flux density parameter as the key moves, which the Hall sensor converts into a corresponding voltage signal. This parameter change approach allows continuous position measurement through a single sensor per key, reducing overall system complexity compared to multiple discrete sensors or mechanical switches.
3Adaptability or versatility
If multiple contacts (two or three bubbles) are used to detect key press force and velocity, then the measurement precision of key press characteristics is improved, but the device complexity increases and the ability to detect continuous key position for organ emulation deteriorates
Solution Approach 1:
The patent makes the Hall sensor multi-functional by using it to detect both key position (for organ emulation) and key velocity/force (for piano emulation) through a single sensor per key. This universality eliminates the need for multiple separate contacts or sensors, reducing device complexity while maintaining or improving adaptability for emulating different instrument types.
Solution Approach 2:
The patent extracts multiple parameters (position, velocity, force) from the continuous voltage signal output by the Hall sensor through mathematical processing. By deriving velocity from the rate of change of position and force from the rate of change of velocity, the system achieves multi-parameter detection with a single sensor, resolving the contradiction between versatility and complexity.
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 solution allows for the accurate detection of key positions, enabling electronic music keyboards to faithfully emulate the sounds of mechanical and electromechanical instruments, including the management of repeated notes on a piano.
Implementation Method 1
The use of magnetic flux density sensors, such as Hall sensors, under each key to detect the position of the key instantaneously
Data Source
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AI summary
An electronic music keyboard (100) comprises a plurality of keys (1 ), a number of magnetic sensors (4) equal to the number of keys, a magnet (5) disposed in each key (1 ), an A/D converter (6) connected to each magnetic sensor (4), a microcontroller (7) connected to the A/D converters (6) and configured to receive digital values (V1,.... Vn) indicative of the key position and convert them into key position values and select useful key position values (P1,...Pm) at which to emit sounds, a digital signal processor (DSP) (8) connected to the microcontroller (7) and configured to receive the useful key position values (P1,...Pm) and accordingly emit at least one sound signal (S*; S1,.... Sk) and an electroacoustic transducer (9) connected to the DSP (8) and configured to receive at least one sound signal (S*; S1,....Sk) and accordingly generate a music sound (S).