Antenna Device for Electronic Timepiece in Metallic Case
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Solution Overview
Problem
Existing antenna designs for electronic timepieces with metallic cases face challenges in maintaining antenna properties and gain due to the metallic environment, battery proximity, and structural complexity, particularly in the 2.4-GHz band and WiFi applications.
Innovation Solution
A three-dimensionally formed antenna device within a metallic case, comprising a first substrate with a ground pattern and power feeding circuit, a second substrate with an antenna element, and a conductive electrode, which reduces deterioration and variance in antenna gain by positioning the antenna element apart from the metallic case and utilizing a ground pattern for improved directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna is arranged inside a metallic case, then miniaturization is achieved, but antenna properties deteriorate due to the metallic environment and proximity to battery and case
Solution Approach 1:
The patent transitions from a planar two-dimensional antenna layout to a three-dimensional configuration by stacking substrates vertically. The antenna element is placed on a second substrate that is positioned at a height above the first substrate containing the battery, creating vertical separation that reduces electromagnetic interference while maintaining compact horizontal footprint.
Solution Approach 2:
The patent introduces a ground pattern on the first substrate as an intermediary layer between the battery and the antenna element. This ground pattern acts as a shielding layer that blocks electromagnetic interference from the battery and metallic case, protecting the antenna properties while allowing the compact metallic case design.
2Reliability
If the chip antenna is arranged at a position different from the circuit board, then antenna properties can be maintained, but the structure becomes complex and miniaturization is difficult
Solution Approach 1:
The patent combines the antenna element and circuit board into a single integrated antenna device structure. The power feeding circuit is formed on the first substrate, the ground pattern is on the first substrate, and the antenna element is on the second substrate, all connected through conductive electrodes, creating a unified compact structure rather than separate components.
Solution Approach 2:
The patent implements a nested multi-layer structure where the first substrate containing the power feeding circuit and ground pattern is stacked with the second substrate containing the antenna element. The conductive electrodes penetrate through the substrates to connect the components, creating a compact nested arrangement that reduces overall size while maintaining proper electrical connections.
3Volume of moving object
If the antenna element is positioned close to the battery and metallic case, then miniaturization is achieved, but gain deteriorates due to interference and proximity effects
Solution Approach 1:
The patent uses vertical stacking to create three-dimensional separation between the antenna element and interfering components. The antenna element on the second substrate is positioned at a vertical distance from the battery and metallic case, reducing near-field interference while maintaining compact horizontal dimensions.
Solution Approach 2:
The ground pattern on the first substrate serves as an intermediary shielding layer between the battery/metallic case and the antenna element. This ground pattern blocks electromagnetic fields from the battery and case, preventing gain deterioration while allowing close proximity positioning for miniaturization.
Data Source
AI summary
An antenna device housed in a metallic case body of an electronic timepiece includes: a first substrate which is provided on the side of a back over of the metallic case body and on which a ground pattern and an wireless communication unit as a power feeding circuit are formed; a second substrate which is arranged on the opposite side of the movement and on which a chip antenna is formed; and a conductive electrode which is arranged inside the movement and has one end connected to the wireless communication unit and the other end connected to the chip antenna.