Plastic Watch Case with Dual Metal Half-Shells
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Solution Overview
Problem
Existing wristwatches with a plastic caseband-bezel covered by a metal cap struggle to maintain a metal-like appearance when the watch is turned over, as the seam between the cap and the plastic case is visible, compromising the perceived quality, especially when accessing the battery.
Innovation Solution
The wristwatch design features an upper and lower half-shell configuration with a gap between them, allowing the crown and push-buttons to pass through, and an annular cap to mask the bezel joint, providing design flexibility and hiding the seam, while using a 0.3 mm thick metal sheet for the half-shells which are glued to the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a metal cap covers the plastic caseband-bezel, then the metal-like appearance is improved, but the seam between the cap and plastic becomes visible when the watch is turned over
Solution Approach 1:
The metal cap is divided into two separate half-shells (upper and lower) that are positioned on opposite sides of the plastic case. This segmentation allows the crown to pass through the gap between them, and each half-shell can be independently shaped to mask seams from both front and back views, resolving the visible seam issue while maintaining metal appearance.
Solution Approach 2:
The invention transitions from a single cap covering only the front to a three-dimensional arrangement with two half-shells positioned at opposite sides of the case. This dimensional change allows the crown to pass through the space between half-shells and enables seam masking from both front and back perspectives simultaneously.
2Shape
If a single metal cap covers the entire case, then the metal appearance is improved, but the design flexibility of the case profile is constrained
Solution Approach 1:
Dividing the metal cap into two independent half-shells allows each half to be designed with different profiles, thicknesses, and geometries. This enables greater design flexibility to accommodate various case shapes, crown positions, and aesthetic requirements while still providing complete metal coverage when assembled.
Solution Approach 2:
The two half-shells are positioned dynamically at opposite sides of the case rather than as a single rigid structure. This dynamic arrangement allows the crown to pass through the gap between them and enables independent optimization of each half-shell's design for specific functional and aesthetic requirements.
3Shape
If the metal cap extends along the side of the case, then the metal appearance is improved, but the manufacturing complexity increases
Solution Approach 1:
The metal cap is segmented into two half-shells that can be manufactured separately using standard metal forming techniques. Each half-shell can be produced independently and then assembled, simplifying manufacturing compared to creating a single complex cap that wraps around the entire case, while still achieving the desired metal appearance extending along the case sides.
Data Source
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AI summary
The wristwatch comprises a strap, a plastic case (1) including a case-bezel, a watch crystal (8), a case back, and two pairs of lugs (12) to which the two ends of the strap are respectively attached. It also includes an upper metal half-case (4) covering the top of the case and part of the case middle, and having an opening through which the crystal is visible. Furthermore, it includes a crown (13) or a pusher (15) projecting from the case middle. It is further characterized in that it also includes a lower half-case (5) covering the case back and part of the case middle. The upper and lower half-cases each have two substantially symmetrical peripheral rims extending opposite each other, the crown or pusher being located in an elongated space extending between the rims of the two half-cases.The elongated space also reveals part of the build.