Lever Arm Capo with Biasing Spring and Cable Adjuster
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Solution Overview
Problem
Lever arm type capos are difficult to apply, prone to flapping when not in use, and experience stress and friction issues due to lateral loads, leading to suboptimal locking and adjustment difficulties.
Innovation Solution
A capo design featuring a top arm, lower arm, and lever arm with a biasing arrangement, such as a spring, that keeps the capo open for easier fitting and restricts movement when not in use, along with an adjuster mechanism with a line of action through the pivot axis to reduce lateral loads and stresses, providing improved locking and compact assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the lever arm capo is designed with a traditional adjusting screw and linkage mechanism, then the capo can accommodate varying neck sizes and regulate string pressure, but the adjuster screw and linkages are subject to lateral and shear loads that induce stresses and increase friction on the threads making adjustment more difficult
Solution Approach 1:
The patent replaces the traditional adjusting screw and linkage mechanism with a cable-actuated system. The cable runs through a guide and connects to the lever arm, eliminating the need for a threaded adjuster screw that is subject to lateral and shear loads. This substitution removes the friction and stress issues associated with the traditional mechanical adjustment system while maintaining the ability to regulate string pressure and accommodate varying neck sizes.
2Device complexity
If the lever arm capo is designed without a biasing arrangement, then the structure remains simple, but the arms are prone to dangle and freely pivot and flap about preventing easy application to the guitar neck
Solution Approach 1:
The patent introduces a biasing arrangement in the form of a spring that urges the lever arm toward the lower arm. This spring provides a restoring force that prevents the arms from dangling and flapping freely when the capo is not in use. The biasing mechanism maintains the arms in a controlled position, making application to the guitar neck easier while adding minimal complexity to the overall structure.
3Ease of operation
If the adjuster mechanism is positioned away from the pivot axis, then it is easier to access and operate, but it experiences increased lateral loads and friction on the threads
Solution Approach 1:
The patent eliminates the threaded adjuster screw entirely and replaces it with a cable-actuated system. The cable is routed through a guide and connected to the lever arm, allowing adjustment to be made by pulling the cable rather than rotating a screw. This substitution removes the lateral loads and friction issues associated with threaded mechanisms positioned away from the pivot axis, while maintaining ease of operation through the cable actuation system.
4Reliability
If the lever arm capo uses a traditional locking mechanism, then positive locking can be achieved, but the differential 'drop off' across the operating range leads to suboptimal locking and potential accidental release
Solution Approach 1:
The patent uses a spring biasing arrangement that provides a consistent restoring force across the entire operating range of the lever arm. This dynamic spring mechanism ensures uniform locking pressure is maintained from the initial contact position through the full range of motion, eliminating the differential 'drop off' experienced by traditional mechanical locking systems. The spring continuously urges the lever arm toward the lower arm, providing reliable positive locking without variation across the operating range.
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 design enhances ease of application, reduces flapping, and ensures secure locking with reduced risk of accidental release, while also allowing for adjustable pressure on instrument strings to accommodate varying neck sizes.
Implementation Method 1
A biasing arrangement, such as a spring, that keeps the capo open for easier fitting and restricts movement when not in use
Implementation Method 2
an adjuster mechanism with a line of action through the pivot axis to reduce lateral loads and stresses
Data Source
AI summary
A capo (10) for use with a stringed instrument comprises a top arm (12), lower arm (16) and a lever arm (24). The top arm (12) is adapted to extend across a fingerboard of the instrument above the strings (4), and a side arm is connected and extending at an angle to the top arm and arranged to extend generally laterally of the neck (2) of the instrument. The lower arm (18) has one end pivotally attached to the side arm (16) at a lower arm pivot (20) and is adapted to abut against the back of the neck of the instrument when in a closed position. The lever arm has one end pivotally attached to the side arm (16) at a pivot (26) spaced from the lower arm pivot (20). The capo further includes an adjuster mechanism (28, 334) that extends and projects an adjustable amount from the lever arm (24) and has an end tip (32) which bears against the lower arm (24).