Camming Surface Actuator for String Load Reduction
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Solution Overview
Problem
Current pitch alteration systems for stringed instruments face challenges in achieving real-time pitch alteration with efficient load reduction, as existing mechanisms are either cumbersome, inefficient, or lack the capability for motorized operation, leading to limited pitch change capabilities and complex mechanical designs that hinder musical expression.
Innovation Solution
A camming surface actuator system with a variable ratio camming surface and a constant force spring is used to reduce string load, allowing for rapid pitch manipulation by human power or a motor, coupled with a control system that enables real-time pitch tracking and compensation for environmental factors, enabling precise and instantaneous pitch changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional pitch alteration devices are used, then pitch can be altered, but the mechanical complexity increases and load reduction is inefficient
Solution Approach 1:
The patent employs a camming surface with a curved profile that converts rotational motion into linear displacement of the string. The camming surface's geometric shape provides mechanical advantage through its radius of curvature, enabling efficient load reduction while maintaining a compact structure. This curved surface approach replaces complex multi-component mechanisms with a single geometric solution.
Solution Approach 2:
The patent incorporates a spring-loaded counterbalance mechanism that offsets the string tension load. The spring force is calibrated to counteract the majority of the string tension, reducing the net load that the camming mechanism must handle. This counterweight approach significantly decreases the mechanical complexity and size of the pitch alteration device.
2Reliability
If tuning systems are used for pitch alteration, then pitch stability is achieved, but real-time pitch alteration capability is lost due to frequency stabilization delay
Solution Approach 1:
The system pre-calculates and stores optimal camming surface profiles for different desired pitch alterations. When a pitch change is requested, the system simply rotates the cam to the pre-determined position corresponding to the desired pitch, eliminating the need for real-time frequency analysis and stabilization. This preliminary preparation enables instantaneous pitch changes while maintaining accuracy.
Solution Approach 2:
The patent implements a feedback mechanism using a pitch detection sensor that monitors the actual string frequency and compares it to the target frequency. The system continuously adjusts the cam position based on the frequency error signal, ensuring accurate pitch attainment while maintaining real-time responsiveness. This closed-loop control achieves both speed and stability.
3Extent of automation
If motorized pitch alteration is implemented, then real-time control is achieved, but the load reduction ratio must be extremely high (500:1 to 2000:1) which increases device complexity
Solution Approach 1:
The spring-loaded counterbalance mechanism offsets the majority of string tension (e.g., 20-30 lbs out of 40-50 lbs total), reducing the net load that the motor must overcome to 10-20 lbs. This counterweight approach reduces the required load reduction ratio from 500:1 or 2000:1 to a more manageable 20:1 or 30:1, significantly simplifying the motor and gear selection.
Solution Approach 2:
The camming surface geometry provides additional mechanical advantage through its curved profile, which converts rotational motor motion into linear string displacement with force multiplication. The cam's radius of curvature and profile shape create a mechanical lever effect that further reduces the motor load requirement, enabling the use of smaller, simpler motors while maintaining real-time control 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
The system achieves significant load reduction and enables real-time motorized pitch alteration with minimal mechanical complexity, allowing for extensive musical expression and precise control of pitch changes, overcoming the limitations of prior art by providing a compact, efficient, and effective solution.
Implementation Method 1
A pitch alteration device is presented which includes a camming surface actuator which comprises: (a) a tension transfer portion adapted to transfer string tension to a camming surface portion via at least one bearing means that rides on at least one camming surface
Implementation Method 2
The variable ratio camming surface reduces the string load by presenting a generally low slope to the tension transfer portion, thereby shunting the bulk of the string load to an axle portion and optimizing a distribution of forces presented to the rotating portion
Implementation Method 3
A camming surface actuator system with a variable ratio camming surface and a constant force spring is used to reduce string load
Data Source
AI summary
A method and apparatus for string load reduction and real-time pitch alteration on stringed instruments. A string load is substantially reduced with a camming surface actuator so that the pitch can be rapidly manipulated by an input force which is generated by human power or an electronically controlled motor. Various types of camming surfaces are provided as well as a load optimization calculation which determines the shape of a variable ratio camming surface. Multiple embodiments are described including a constant force pitch alteration device, a motorized control system with pitch compensation and real-time tracking of string pitch to multiple relative input signals, a control signal generator based on real-time position measurement of a control object relative to an electromagnetic radiation sensor, and methods for generating mechanical looping, vibrato, and polyphonic chorus effects which can be automated or dynamically controlled by a user. Other embodiments are described and shown.