Phone Plug Tip Geometry for Out-of-Spec Jacks
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Solution Overview
Problem
¼ inch diameter male phone plugs often fail to mate properly with female jacks due to spring contacts being out of specification, leading to poor electrical contact and retention issues.
Innovation Solution
The shape of the phone plug tip is modified by moving the convex bulbous portion forward and increasing the length of the adjacent concave detent portion, with specific dimensional changes such as a convex annular shoulder centered closer to the front end and a longer waist with greater radius curvature, to accommodate out-of-specification jack springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the phone plug tip follows standard specifications, then compatibility with standard jacks is maintained, but retention and electrical contact deteriorate when jacks are out of specification
Solution Approach 1:
The patent modifies the geometric parameters of the phone plug tip, specifically moving the convex bulbous portion forward to a position less than 0.120 inch from the front end (compared to standard positioning), increasing the radius of curvature of the concave waist to greater than 0.75 inch, and adjusting the axial length of the waist. These parameter changes enable the tip to accommodate spring contacts that are out of specification while maintaining compatibility with standard jacks.
2Ease of manufacture
If the spring contact length in jacks is out of specification, then manufacturing cost is reduced, but electrical contact and retention deteriorate
Solution Approach 1:
The patent applies local quality by creating specific geometric features at critical locations on the plug tip. The convex bulbous portion positioned less than 0.120 inch from the front end provides a localized contact point that compensates for spring length variations in jacks, while the concave waist with increased radius of curvature provides a localized detent feature that enhances retention. These localized geometric modifications allow the plug to work with jacks having out-of-specification spring contacts without requiring changes to the entire plug structure.
3Adaptability or versatility
If the convex bulbous portion is moved forward and the concave detent portion is lengthened, then accommodation of out-of-specification springs is improved, but deviation from standard specification increases
Solution Approach 1:
The patent systematically changes key geometric parameters of the tip: positioning the convex annular shoulder at an axial distance less than 0.120 inch from the front end, increasing the radius of curvature of the concave waist to greater than 0.75 inch, and adjusting the axial length of the waist. These controlled parameter changes provide improved adaptability while maintaining manufacturing feasibility.
Data Source
AI summary
An electric plug having a central signal shaft terminating in a tip, wherein the tip has a substantially frustoconical nose, a convex annular shoulder centered at an axial distance of less than 0.120 inch from the front end of the tip, (defining a bulbous portion) and a concave waist having a radius of curvature greater than about 0.75 inch, defining the detent adjacent to the bulbous portion.