Removable Watch Case Back for Wireless Charging Heat Shielding
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Solution Overview
Problem
Existing smart watches face inefficiencies in battery charging due to wasted space and improper recharging connections, leading to potential heat issues from electromagnetic field interactions with metal components during wireless charging.
Innovation Solution
A removable watch case back with an integrated electronic device featuring an inductive coil on a printed circuit board, a magnetic shield, and a flexible connector, allowing for efficient wireless charging while minimizing space and enhancing mechanical shock resistance, and incorporating a ceramic or plastic base support for waterproofing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless charging coil is integrated in the watch case back, then wireless charging efficiency is improved, but heat generation from electromagnetic field interaction with metal parts increases
Solution Approach 1:
A magnetic shield made of ferrite material is introduced as an intermediary between the wireless charging coil and metal parts of the watch. This shield intercepts and guides the electromagnetic field, preventing harmful interactions with metal components while maintaining charging efficiency. The ferrite material specifically targets and contains the magnetic flux within the shield structure itself.
Solution Approach 2:
The magnetic shield converts potentially harmful electromagnetic field leakage into a beneficial contained magnetic flux. By designing the shield with specific geometric features and ferrite material properties, the electromagnetic energy that would otherwise heat metal parts is redirected and contained within the shield structure, actually improving the overall efficiency of the wireless charging system.
2Object-affected harmful factors
If shield is added to prevent field leaks, then heat risks are reduced, but device complexity increases
Solution Approach 1:
The magnetic shield is integrated with the watch case back structure, merging the shielding function with the existing housing component. This eliminates the need for separate shield elements and reduces overall device complexity while maintaining heat protection benefits.
Solution Approach 2:
The magnetic shield serves multiple functions simultaneously: it acts as a heat barrier, a structural support element, and an aesthetic component of the watch case back. This multi-functionality reduces the need for additional separate components, thereby minimizing device complexity.
3Ease of manufacture
If charging coil is not arranged conveniently inside the watch case, then manufacturing is simplified, but recharging efficiency is reduced due to space waste and poor connection
Solution Approach 1:
The magnetic shield is designed with non-uniform thickness and selective material distribution, with thicker sections positioned strategically near the charging coil and thinner sections in other areas. This localized optimization ensures efficient electromagnetic field containment where needed while minimizing overall material usage and maintaining manufacturing simplicity.
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
Enables efficient wireless charging with reduced heat risks, improved mechanical shock resistance, and easier component access, while maintaining a compact and aesthetically pleasing design.
Implementation Method 1
Wireless charging can be based on the principle of electrical induction, whereby the flow of an electric current through a coil creates a current in a nearby coil. For a watch, one of the coils (the receiver coil) is mounted in the watch case back, whereas another coil (the charger coil), nearby and powered by an electric current, will produce a magnetic field, which creates an electric current induced in the (receiver) coil, to power the battery.
Implementation Method 2
a movable element operationally connected to at least one part of the case and comprising one or more magnets which generate a magnetic field that passes through the conductive coil, a first charging circuit electrically connected to the conductive coil for wirelessly receiving power from an external device using the conductive coil
Implementation Method 3
the proximity of metallic elements, such as certain external components of the watch, can reduce efficiency during recharging of the battery. Further, the electromagnetic field between the two coils will induce a current in nearby metal parts. This induced current risks causing these metal parts to heat up. In such case, it is envisaged to provide a shield for the watch coil to avoid field leaks. This shield may be a ferrite.
Data Source
AI summary
A removable case back of an electronic or electromechanical watch case, the case back allows the wireless charging or recharging of a power source. The case back includes a first multi-function sub-assembly having a buzzer, an inductive coil on or integrated in a printed circuit board, the inductive coil being covered by a magnetic shield on an inner side of the watch case, and a second multi-function sub-assembly on the first multi-function sub-assembly having an enclosure structure for accommodating the power source, such as a battery or an accumulator.