Watch Strap Fastening Device with Offset Securing Element
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Solution Overview
Problem
Existing wrist strap fastening devices require complex movements and a flattened region on watch cases, making them difficult for unpracticed users and limiting design flexibility, while also risking accidental detachment.
Innovation Solution
A wrist strap fastening device with a pivotable blocking element and a securing element that automatically secures and releases the wrist strap pin using two grooves, allowing for simplified attachment and detachment with one movement and eliminating the need for a flattened region on the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a securing element with shaft is attached closely to the case-side end of the fastening device, then the securing function is improved, but a flattened region or notch is required on the watch case which limits design flexibility
Solution Approach 1:
The shaft of the securing element is positioned in a plane that is offset from the central axis of the fastening device, specifically in a lateral dimension. This dimensional relocation allows the shaft to engage with the case without requiring a flattened region, as it passes through the rounded case profile in a different spatial plane, thus resolving the conflict between securing reliability and case design flexibility
Solution Approach 2:
The fastening device employs an asymmetric arrangement where the securing element's shaft is positioned laterally offset rather than centrally. This asymmetric positioning allows the shaft to clear the rounded case profile without requiring symmetric flattened regions, enabling the case to maintain its aesthetic rounded shape while still providing secure engagement
2Reliability
If the fastening device requires two translational movements followed by a rotational movement, then the securing mechanism is robust, but the operation becomes complicated for unpracticed users
Solution Approach 1:
The attachment operation merges two previously separate movements (translation and rotation) into a single combined motion. The linking member is designed so that inserting it into the case automatically performs both the translational insertion and the rotational engagement in one continuous action, eliminating the need for users to execute multiple discrete movements while maintaining secure attachment
Solution Approach 2:
The linking member is pre-configured with its securing elements and grooves in specific positions before insertion. This preliminary arrangement ensures that when the user performs the single insertion motion, the components automatically align and engage in the correct sequence without requiring the user to manually perform intermediate alignment or positioning actions
3Device complexity
If the wrist strap pin is secured with a single groove, then the device structure is simple, but accidental detachment may occur reducing reliability
Solution Approach 1:
Different grooves are provided with different local qualities and orientations. The first groove in the linking member and the second groove in the blocking element are positioned at different locations and oriented at different angles relative to the wrist strap pin. This local differentiation creates multiple independent engagement points, preventing accidental detachment while maintaining overall structural simplicity
Solution Approach 2:
The securing mechanism is segmented into two separate grooves located in different components (linking member and blocking element). This segmentation distributes the securing function across multiple independent elements, each contributing to the overall reliability. The wrist strap pin engages with both grooves simultaneously, creating a multi-point secure connection that is more reliable than a single groove while keeping each individual groove structurally simple
Data Source
AI summary
A device for fastening a wrist strap, in particular a watch strap, to a watch case, the device having a linking member, to which a strap end member of the wrist strap can be fastened and the case-side end of which can be fastened to a wrist strap pin attached laterally to the case. A securing element, which is biased against the case and has an interlocking projection located thereon, is arranged on the linking member such that the securing element can assume two positions, a first, secured position, in which the wrist strap pin is positioned in an indentation in the linking member and the securing element prevents the linking member or the wrist strap from becoming detached from the wrist strap pin and from the case, and a second, opened position, in which the wrist strap pin can be guided out of or into the indentation.