Electronic Timepiece Component Layout for Wireless Charging
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Solution Overview
Problem
The use of a large diameter secondary battery in electronic timepieces results in decreased charging efficiency due to overlapping with conductive components like the motor coil and train wheel, blocking magnetic flux and hindering efficient wireless power transfer.
Innovation Solution
The secondary battery, first motor coil, and first train wheel are positioned to avoid overlap in plan view, with the charging coil having a central axis parallel to the pointer shaft, and the case is designed with non-conductive and conductive components to minimize magnetic flux interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a large diameter secondary battery is used to extend battery life, then the battery can be driven for approximately 6 months from full charge, but the secondary battery substantially equivalent to a metal component having a large thickness blocks magnetic flux of the charging coil, causing charging efficiency to decrease
Solution Approach 1:
The patent repositions the secondary battery from a vertical arrangement (overlapping with the motor coil in the thickness direction) to a horizontal arrangement (side-by-side in the plan view). This dimensional change allows the battery to be disposed at positions that do not overlap with the motor coil or train wheel in plan view, while still maintaining sufficient battery capacity for extended operation. The battery is arranged radially around the pointer shaft, utilizing the radial space efficiently without blocking the magnetic flux path of the charging coil.
2Loss of energy
If the secondary battery is disposed to avoid overlapping with the motor coil and train wheel, then charging efficiency is improved, but the device complexity increases due to adjusted component layout
Solution Approach 1:
The case back is designed with a dual-functionality: it serves as both the structural closure of the timepiece and as a non-conductive barrier to protect the charging coil from magnetic flux interference by the conductive components. The case back includes a through-hole for the pointer shaft and is positioned to surround the charging coil, effectively isolating it from the conductive secondary battery, motor coil, and train wheel while maintaining the overall structural integrity of the device.
Solution Approach 2:
The case back acts as an intermediary element between the charging coil and the conductive components (secondary battery, motor coil, train wheel). By positioning the case back to surround the charging coil and utilizing its non-conductive properties, it mediates the magnetic flux interaction, preventing the conductive components from blocking the magnetic flux while still allowing the battery to be positioned close to the charging coil for efficient wireless power transfer.
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
This configuration enhances charging efficiency by reducing magnetic flux obstruction and allows for a thinner design while supporting rapid charging with all-solid-state batteries.
Implementation Method 1
a charging coil that has a central axis parallel to the pointer shaft, and a secondary battery that is charged through wireless power supply from an external charger via the charging coil
Data Source
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AI summary
An electronic timepiece includes a dial, a pointer shaft that is disposed at a center of the dial, a hour hand, a minute hand, and a seconds hand that are attached to the pointer shaft and that display time, a first train wheel that includes a conductive gear and that is coupled to the hour hand, the minute hand, and the seconds hand, a first motor that includes a first motor coil and that drives the hour hand, the minute hand, and the seconds hand via the first train wheel, an annular charging coil that has a central axis parallel to the pointer shaft, and a secondary battery that is charged through wireless power supply from an external charger via the charging coil and that supplies power to the first motor, and the secondary battery, the first motor coil, and the first train wheel are disposed at positions that do not overlap each other in plan view.