Reversible Wristwatch Case Indexing Mechanism
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Solution Overview
Problem
Existing wristwatch designs with reversible cases suffer from unreliable locking mechanisms due to insufficient spring stiffness, leading to inadvertent pivoting and imprecision in defining rest and pivoting positions, which worsens with wear.
Innovation Solution
Incorporating a first longitudinal indexing element on the trunnion that cooperates with a second indexing element on the case to precisely define rest and pivoting positions, using a securing section with transverse notches and elastically deformable strips for reliable indexing, and a compact hinging device that integrates locking and guiding functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a return spring is used to lock the insert in the rest position, then the locking mechanism is simple in structure, but the locking reliability deteriorates when the spring is insufficiently stiff, leading to inadvertent pivoting
Solution Approach 1:
The patent replaces the spring-based mechanical locking system with a detent mechanism featuring a cam surface and detent ball. The cam surface provides a mechanical advantage that ensures positive engagement and reliable locking without depending on spring stiffness, thereby eliminating inadvertent pivoting while maintaining structural simplicity.
Solution Approach 2:
The detent ball is pre-positioned in engagement with the cam surface before any pivoting motion occurs. This preliminary engagement ensures that the insert is securely locked in the rest position from the outset, preventing any unintended movement before the user intentionally actuates the release mechanism.
2Ease of manufacture
If the rest and pivoting positions are delimited solely by component abutment and spring compression, then the assembly is simple to manufacture, but the position precision deteriorates, causing user-perceived imprecision that worsens with wear
Solution Approach 1:
The patent replaces imprecise component abutment with a cam surface and detent ball mechanism that provides positive mechanical indexing. The cam surface geometry precisely defines the rest position, while the detent ball engagement provides a distinct tactile and visual indication of the pivoting position, ensuring consistent precision that does not deteriorate with wear.
Solution Approach 2:
The cam surface serves multiple functions: it defines the rest position precision, provides the locking surface for the detent ball, and guides the insert during the pivoting transition. This multi-functionality achieves precise position definition without adding separate positioning components, maintaining manufacturing simplicity while improving precision.
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 solution enhances the reliability and precision of turning the case over relative to the wristband, improving user experience and assembly quality by providing precise angular positioning and reducing play in the assembly.
Implementation Method 1
at least one elastically deformable strip fixed inside the case so as to index the associated insert respectively in the rest position and in the pivoting position
Data Source
AI summary
The wristwatch with a reversible case (12) is provided with a wristband, each end strand of which includes an insert (30) which is pivotably and slidably mounted on the case (12) via a trunnion (32). Each insert (30) includes at least two indexed angular positions, which respectively correspond to two positions of use of the case (12), and at least one longitudinal rest position wherein the insert (30) is blocked from pivoting by a male element (36) fitting inside a female element (38), one of the elements (36) being arranged on the case (12), the other element (38) being arranged on the insert (30), and a longitudinal pivoting position wherein the insert (30) is shifted longitudinally outwards and wherein the insert (30) is free to pivot. The invention is characterized in that each trunnion (32) includes a first indexing element (48), which cooperates with a second indexing element (64, 66) arranged on the case (12) so as to index the insert (30) longitudinally.