Optical Sensor for MIDI Stringed Instruments
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Solution Overview
Problem
Existing MIDI instruments face challenges in accurately separating signals from individual strings due to mutual interference and the influence of sensors on string vibrations, with standard sensors failing to provide detailed mechanical data for precise sound generation and compact design.
Innovation Solution
An optical sensor with a housing containing an optical emitter and receiver configured to form light beams parallel to the string, featuring two photosensitive surfaces and a light beam modulator that adjusts illumination areas in both horizontal and vertical planes, reducing sensor influence and enabling accurate signal differentiation in two perpendicular planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard electromagnetic or piezoelectric sensors are used, then signal detection is achieved, but mutual interference between strings and sensor influence on string vibrations occurs
Solution Approach 1:
The patent replaces electromagnetic and piezoelectric sensors with an optical sensing system. The optical emitter projects light beams that reflect off the vibrating string to the optical receiver, eliminating mechanical contact and electromagnetic interference. This substitution resolves the contradiction by achieving signal detection without the harmful effects of traditional sensor-string interaction.
Solution Approach 2:
The patent introduces light as an intermediary medium between the string and the sensor system. Instead of direct sensor-string contact, the optical beams serve as mediators that carry vibration information from the string to the detector without physical or electromagnetic coupling, thereby eliminating mutual interference between adjacent strings.
2Measurement precision
If optical sensors with emitters and receivers placed above, under, or along strings are used, then high-quality signal separation is achieved, but instrument size increases and convenience decreases
Solution Approach 1:
The patent merges the optical emitter and receiver into a single integrated sensor unit positioned at one location (e.g., at the bridge or soundhole). This consolidation eliminates the need for separate components distributed along the string length, reducing instrument bulk while maintaining the optical path for high-quality signal detection.
Solution Approach 2:
The patent positions the optical sensor unit in a compact configuration where the light path travels through available space (e.g., along the string axis or through the body cavity) rather than requiring linear placement along the string. This dimensional arrangement achieves signal separation without increasing instrument footprint.
3Measurement precision
If separate sensors are used for each string, then signal separation is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs a single optical sensor unit that can detect vibrations from multiple strings simultaneously. By projecting light beams across several strings and using signal processing to differentiate their vibrations, the system achieves separate signal detection without requiring separate physical sensors for each string, thereby reducing complexity.
Solution Approach 2:
The patent segments the detection function at the signal processing level rather than the hardware level. The optical receiver captures combined light reflections from multiple strings, and subsequent processing separates the individual string signals based on their unique vibration frequencies and patterns, achieving functional segmentation without physical multiplication of sensors.
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 solution achieves high-quality signal separation and compact design, allowing for precise sound generation with reduced interference between strings and sensor influence, enabling accurate representation of complex string vibrations in three-dimensional space.
Implementation Method 1
Optical sensors (a signal pickup is achieved using the effect of a light beam reflected from a vibrating string on a light-sensitive element)
Implementation Method 2
optical receiver comprises at least two photosensitive surfaces... configured to adjust an area of an illuminated part of the upper photosensitive surface and an area of an illuminated part of the lower photosensitive surface
Data Source
AI summary
The inventions relate to the field of electric musical instruments, more particularly, to an optical sensor for a stringed musical instrument with a digital interface and to a stringed musical instrument with a digital interface equipped with said sensor (MIDI—Musical Instrument Digital Interface).Implementation of the disclosed inventions allows to obtain a signal corresponding to vibrations (deflections) of a string in two mutually perpendicular planes, with the influence of the device generating such signals on string vibration parameters being reduced, without signals generated by different strings being mixed and with dimensions of the optical sensor being reduced to allow for its compact placement on a stringed musical instrument.