Timepiece Antenna Ground Sheet Layout for Stable Wrist Communication

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Solution Overview

Problem

The sensitivity of antennas in electronic devices is often reduced due to the influence of the device case and internal components, leading to lower transmission and reception of radio waves.

Innovation Solution

The implementation of a conductive sheet extending perpendicular to the antenna pattern and connected to the ground plane, along with additional conductive sheets acting as reflective plates, enhances the antenna's sensitivity and beamwidth, particularly in the direction of communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an antenna is arranged in an electronic device with a case and internal components, then the device structure is complete and functional, but the antenna sensitivity is reduced due to radio wave attenuation by the case and components

Engineering Contradiction:
Improveantenna sensitivityVSAvoidradio wave attenuation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A conductive sheet is introduced as an intermediary component between the antenna element and the case. This conductive sheet serves as a ground plane that reflects and directs radio waves, preventing their attenuation by the case and internal components. The conductive sheet is electrically connected to the antenna element, creating an artificial ground plane that improves antenna radiation characteristics without requiring a large natural ground plane structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the electrical parameters of the antenna system by introducing a conductive sheet with specific electrical conductivity properties. This conductive sheet modifies the electromagnetic field distribution around the antenna element, changing the radiation pattern and improving sensitivity. The conductive sheet's electrical properties are optimized to enhance radio wave transmission and reception despite the presence of the case and components.

Inventive Principle:
Principle #35Parameter changes

2Volume of moving object

If a conventional antenna arrangement is used in a compact electronic device, then the device size is reduced, but the antenna performance deteriorates due to limited space for ground plane and antenna pattern

Engineering Contradiction:
Improvedevice sizeVSAvoidantenna performance
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent transitions from a two-dimensional ground plane arrangement to a three-dimensional configuration by positioning the conductive sheet vertically between the antenna element and the case. This vertical arrangement creates an artificial ground plane that utilizes the third dimension (height), allowing effective antenna operation in compact devices without requiring large lateral ground plane areas. The conductive sheet's vertical orientation optimizes space utilization while maintaining antenna performance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 improves the antenna's reception sensitivity and beamwidth, ensuring stable communication even when the device orientation changes, such as when worn on a wrist.

Implementation Method 1

a first conductor disposed between the case and the antenna element, having a surface substantially parallel to a second axis direction along the central axis of the case, and electrically connected to a ground plane for the antenna element

Methodology Applied
Scientific EffectElectromagnetic wave reflection: Reflection

Data Source

PatentEP4379478B1Electronic device and electronic timepiece
Publication Date: 2026.04.22 CASIO COMPUTER CO LTD
  • EP4379478B1 patent drawingFigure 1
  • EP4379478B1 patent drawingFigure 2A~2B
  • EP4379478B1 patent drawingFigure 3A~3B

AI summary

An electronic device (1) includes a case (2), an antenna element (31) and a first conductor (71). The case (2) has a space inside and includes an insulating material. The antenna element (31) is disposed in the case (2) and includes an antenna pattern (311). The antenna pattern (311) includes at least a part extending substantially parallel to a first axis direction (X) perpendicular to a central axis (C) of the case (2). The first conductor (71) is disposed between the case (2) and the antenna element (31), has a surface substantially parallel to a second axis direction (Z) along the central axis (C) of the case (2), and is electrically connected to a ground plane for the antenna element (31).