Watch Crown Guide Stabilizes Axial Movement and Screw Lock
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Solution Overview
Problem
Existing portable timepieces face instability and difficulty in smoothly releasing the screw lock mechanism, leading to potential damage and hindrances in mass production due to the design of the crown head and rotational force transmitting portion.
Innovation Solution
A portable timepiece design featuring a crown guide that supports the crown head from the inside, allowing stable axial movement and proper mesh alignment, along with a rotational force transmitting portion that can be easily worked on using standard tools, eliminating the need for special devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the crown head is designed without internal support structure, then the manufacturing process is simpler, but the crown head shakes and becomes unstable during screw lock release and engagement
Solution Approach 1:
The crown head is divided into functional zones: an upper operational portion and a lower support portion. The rotational force transmitting portion is positioned in the upper portion for easy access, while the crown guide is positioned in the lower portion to provide stability during operation, separating the operational and support functions spatially
Solution Approach 2:
The crown guide acts as an intermediary support structure between the crown head and the case band. It provides a guiding surface that stabilizes the crown head during axial movement without interfering with the rotational force transmission between the crown and crown shaft
2Device complexity
If the female screw portion is made continuous with the rotational force transmitting portion, then the crown head structure is simplified, but the rotational force transmitting portion becomes difficult to work and requires special devices
Solution Approach 1:
The crown head is segmented into distinct functional portions: the female screw portion for locking, the rotational force transmitting portion for power transmission, and the crown guide for support. This segmentation allows each portion to be optimized independently, with the rotational force transmitting portion positioned to be accessible for working while maintaining structural integrity
Solution Approach 2:
Different portions of the crown head are given different local qualities and geometries suited to their specific functions. The rotational force transmitting portion is designed with a deformed shape and positioned at a specific location that facilitates easy working with standard tools, while the female screw portion maintains its threading characteristics
3Ease of operation
If the crown head is allowed to move freely during screw lock release, then the operability is improved, but the crown head shakes and the mesh alignment becomes difficult
Solution Approach 1:
The crown guide serves as an intermediary guiding mechanism that facilitates controlled movement of the crown head during screw lock release. It provides a precise geometric relationship between the crown head and case band, ensuring proper mesh alignment while allowing the necessary axial movement for operation
4Strength
If the rotational force transmitting portion is positioned deep inside the crown head, then the structural integrity is improved, but the working process requires special devices and becomes more complex
Solution Approach 1:
The crown head is segmented into an upper operational portion and a lower support portion, with the rotational force transmitting portion positioned in the upper portion. This segmentation allows the rotational force transmitting portion to be accessible for working with standard tools while maintaining the overall structural integrity of the crown head through the integrated design
Solution Approach 2:
The rotational force transmitting portion is positioned at a specific radial and axial location within the crown head structure, creating a multi-dimensional arrangement that allows access for working from the outer periphery while maintaining structural integrity through the distributed design of the crown head
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
Enhances the operability and workability of the crown head during screw lock release and engagement, preventing shaking and facilitating smooth mesh alignment, while allowing for efficient manufacturing processes.
Implementation Method 1
an elastic member which urges the crown head in a direction of separation from the case band
Data Source
AI summary
A portable timepiece has a timepiece movement disposed in a case band. A pipe extends through and is attached to the case band and has a male screw portion on a part of the pipe that extends outside the case band. A crown has a crown head and a crown shaft, and the crown head has a female screw portion threadedly engaged with the male screw portion and disengageable therefrom in response to rotation of the crown head in a loosening direction accompanied by axial movement of the crown head in a direction away from the case band. The crown shaft has one end portion that extends into the pipe and is connected to a hand setting stem of the timepiece movement and another end portion that extends outside the case band beyond the pipe and slidably contacts an inner peripheral surface of the crown head to support the crown head and guide the axial movement thereof. The crown shaft has a force receiving portion for receiving a rotational force to rotate the hand setting stem, and the crown head has a force transmitting portion that releasably engages with the force receiving portion during axial movement of the crown head away from the case band to enable a rotational force to be transmitted to the force receiving portion by rotating the crown head. The end portion of the crown shaft that slidably contacts the inner peripheral surface of the crown head constitutes the force receiving portion of the crown shaft.