Tool-Free Watch Bracelet Attachment via Pivoting Flat-Bar Lock
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Solution Overview
Problem
Existing watch strap or bracelet attachment devices require tools for removal, are structurally complex and costly to manufacture, and may pose risks to the wearer due to protruding elements.
Innovation Solution
A device featuring a cylindrical bar with flat portions that fits inside a complementary insert on the bracelet, allowing for easy interchangeability without tools, using axial retaining elements and ball catches for secure positioning, and a removable cap for assembly convenience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional bar with pistons and elastic member is used for attaching the bracelet, then the attachment is secure, but the device requires tools for detachment and has complex structure
Solution Approach 1:
The traditional single-bar structure with multiple components (pistons, elastic members) is segmented into a modular system: a simple bar with flat portions and a separate insert with corresponding blind housings. This segmentation eliminates the need for complex internal mechanisms while maintaining secure attachment through the complementary flat portion-blind housing interface.
Solution Approach 2:
The complex piston-elastic member mechanism is completely extracted and replaced by a simpler geometry-based locking system. The flat portions on the bar engage with blind housings in the insert, creating a secure connection without requiring movable parts or elastic elements within the bar itself.
2Ease of operation
If a tool is provided for pushing pistons back to detach the bracelet, then detachment is possible, but the tool is inconvenient and requires the wearer to be permanently equipped with it
Solution Approach 1:
The attachment system is designed to be self-servicing through the control member that pivots the bar between locked and unlocked positions. The wearer can independently operate the attachment and detachment functions by simply pivoting the control member, eliminating the need for external tools or specialized equipment.
3Ease of operation
If an actuating member protruding through the tube is added to allow tool-free detachment, then the bracelet can be removed without tools, but the protruding element may catch or injure the wearer
Solution Approach 1:
Instead of having the actuating member protrude outward through the tube (which creates injury risk), the design inverts the approach by having the control member pivot the entire bar assembly within the housing. The actuation point is moved to a safe location that does not protrude, eliminating the harmful effect while preserving the tool-free operation capability.
4Adaptability or versatility
If openings are made in the tube or pistons are transformed to achieve interchangeable bracelets, then bracelet interchangeability is enabled, but manufacturing costs increase significantly
Solution Approach 1:
The bar is designed with asymmetric flat portions at specific locations that engage with corresponding blind housings in the insert. This asymmetric geometry enables interchangeable bracelet functionality through simple geometric complementarity rather than complex modifications, significantly reducing manufacturing costs while achieving the desired versatility.
Data Source
AI summary
A device for attaching a bracelet or strap to a watch case includes a bar secured to the watch case by at least one horn and an insert integral with the end of the bracelet. The bar and the insert are complementary in order to cooperate by fitting one inside the other to form a removable assembly to make the bracelet interchangeable. The bar is formed by a cylindrical arbor having at least one flat portion. The flat portion cooperates by fitting with a housing made in the insert. The housing has a substantially rectangular opening for receiving the flat portion. The bar includes a control member for pivoting the bar from a first position A, in which the insert is positioned on the arbor, to a second position B, in which the insert is locked onto the bar.