Watch Winding Stem Locking Device with Friction Feedback
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Solution Overview
Problem
Existing solutions for releasing the pull-out finger from the radial groove of the winding stem in watch movements are unclear in operation, making it difficult for watchmakers to determine when to remove the winding stem, potentially leading to excessive force or unnecessary tool use.
Innovation Solution
A locking device for the winding stem that includes a pull-out with a movable axis, a locking screw, and first and second stop members. The locking screw, integral with the axis, rotates to move the pull-out between locking and release positions, with friction torques from the stop members clearly indicating these positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pointed tool is used to press the pull-out shaft axially to release the pull tab finger from the radial groove, then the winding stem can be released, but the watchmaker cannot determine when the finger is completely clear of the groove, leading to excessive force or unnecessary tool use
Solution Approach 1:
The patent implements a visual feedback mechanism where the locking screw's rotational position indicates the release status. When the locking screw is rotated to a specific position, its head becomes visible or aligns with a reference mark, providing clear feedback to the watchmaker that the pull tab finger is completely clear of the radial groove. This eliminates the information loss about release status.
2Ease of operation
If the pull-out shaft is moved axially to release the pull tab finger, then the winding stem can be removed, but a specific tool such as a pointed tool is required instead of a common tool like a screwdriver
Solution Approach 1:
The patent makes the release mechanism universal by using a locking screw with a standard drive interface (such as Phillips or flathead) that can be operated with common screwdrivers. This replaces the specialized pointed tool requirement, allowing the same tool to serve multiple functions including both tightening/loosening operations and the release operation, thereby improving tool compatibility and versatility.
3Reliability
If the pull tab finger is released from the radial groove by axial movement, then the winding stem can be removed, but the operation is unclear and may lead to excessive force being exerted
Solution Approach 1:
The patent employs visual indicators that change position or become visible when the release is complete. The locking screw may have a colored ring, a reflective surface, or simply its head becomes visible at a specific rotational position, providing a clear visual signal that release is complete. This makes the detection of release completion straightforward and eliminates uncertainty about whether the finger is fully clear of the groove.
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 locking device allows for clear identification of locking and release positions, facilitating the removal of the winding stem without excessive force or unnecessary tool use, and enabling the use of a common tool like a screwdriver.
Implementation Method 1
the locking screw being subjected to a friction torque by the first stop member, and a position for releasing the winding stem, in which the pull-piece is intended to be disengaged from the radial groove of the winding stem, the locking screw being subjected to a friction torque by the second stop member
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a locking device (10) for a winding stem (20) of a watch movement, comprising a pull-piece (11) extending between two ends, one of which is intended to be engaged in a radial groove (21) of the winding stem (20), said pull-piece (11) comprising, between its two ends, an axis (110) by which it is capable of being movable in rotation relative to the winding stem (20), the locking device (10) being characterized in that it further comprises a locking screw (12) and a first and a second stop member (13, 14), said locking screw (12) being configured to be integral with the axis (110) in translation, so that the rotation of the locking screw (12) causes the displacement of the pull-piece (11) between a locking position of the winding stem (20), in which the pull-piece (11) is intended to be engaged in the radial groove (21) of the winding stem (20),the locking screw (12) being subjected to a friction torque by the first stop member (13), and a position for releasing the winding stem (20), in which the pull tab (11) is intended to be released from the radial groove (21) of the winding stem (20), the locking screw (12) being subjected to a friction torque by the second stop member (14).,