Water-Resistant Watch Case with Domed Contact Interface
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Solution Overview
Problem
Existing water-resistant watch cases are not adequately designed to withstand high water pressures during deep dives, leading to potential water ingress and mechanical failure.
Innovation Solution
The watch case features a direct contact between the crystal and the middle on an annular contact line, with an inclined annular peripheral surface on the crystal and a complementary inclined annular inner surface on the middle, forming a domed contact surface that distributes pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional packings and sealing methods are used in watch cases, then the assembly is simpler to manufacture, but the water-resistance cannot withstand high water pressures during deep dives below 4000m
Solution Approach 1:
The patent applies spheroidality by forming a dome-shaped protrusion on the inner surface of the back and a corresponding recess in the middle. This curved geometric configuration allows the back to flex and absorb high water pressures during deep dives, preventing water ingress while maintaining structural integrity. The dome-recess arrangement transforms the rigid sealing approach into a flexible pressure-absorbing mechanism.
2Strength
If a dome made of resistant metal is provided bearing against the back and middle, then the structure can withstand higher pressures, but the tapping can still be damaged at high water pressure
Solution Approach 1:
The patent applies local quality by concentrating the pressure-absorbing function in a specific localized area through the dome-shaped protrusion on the back and its corresponding recess in the middle. This localized structural feature allows the back to flex and absorb high water pressures at the critical sealing interface, preventing water ingress while protecting the tapping from damage during deep dives.
3Volume of moving object
If conical surfaces are used for direct contact between crystal and middle, then the assembly is more compact, but it is difficult to ensure good direct contact due to geometry mismatches impacting mechanical strength
Solution Approach 1:
The patent applies spheroidality by replacing the conical contact surfaces with a dome-shaped protrusion and corresponding recess arrangement. This curved geometric configuration ensures optimal contact between the back and middle, distributing mechanical stresses evenly and maintaining strong mechanical bonds while accommodating the compact design requirements of the watch case.
4Reliability
If soft metal packing is used between crystal and middle, then water-resistance is improved, but the packing must be changed every time the watch case is opened
Solution Approach 1:
The patent applies the taking out principle by removing the soft metal packing element from the crystal-to-middle assembly. Instead, it uses a direct mechanical bond between the crystal and middle components, eliminating the need for replaceable packing materials. This extraction of the soft packing eliminates maintenance requirements while maintaining water-resistance through the engineered direct contact interface.
Data Source
AI summary
The water-resistant watch case includes at least one crystal mounted on an upper side of a middle, a fastening gasket positioned between an upper annular inner wall of the middle and an upper annular outer wall of the crystal. The crystal includes an annular peripheral surface below the upper annular outer wall inclined at an angle smaller than 90° in relation to an axis perpendicular to a plane of the watch case. The peripheral surface comes into contact against an annular inner surface of the middle inclined at an angle similar to the inclination of the annular peripheral surface and below the upper annular inner wall of the middle. The annular peripheral surface and/or the annular inner surface of the middle includes a domed contact portion for a contact on an annular contact line between the two surfaces.