Timepiece Ground Terminal Plate for Stable Back Cover Contact

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Solution Overview

Problem

Existing electronic devices and timepieces face challenges in maintaining a stable electrical connection due to the repeated opening and closing of components like the back cover, which leads to abrasion and decreased spring functionality, resulting in varying contact resistance.

Innovation Solution

The electronic device incorporates a metal component externally mounted to a case, a metal plate inside the case functioning as GND, and an internal terminal plate sandwiched between the case and the metal plate, ensuring a stable electrical connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a terminal plate with spring characteristics is used to maintain electrical connection with the back cover, then electrical connectivity is achieved, but the contact portion is gradually abraded with repeated opening and closing, causing spring functionality to decrease and contact resistance to vary

Engineering Contradiction:
Improveelectrical connection stabilityVSAvoidservice life of spring terminal plate
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The invention divides the terminal plate into two separate components: a fixed terminal plate attached to the case and a movable contact portion on the back cover. This segmentation allows the fixed terminal plate to remain stationary and avoid wear, while the movable contact portion is designed to be replaceable. By separating the functions of electrical connection and mechanical movement, the system achieves stable long-term electrical connectivity without the wear problems of integrated spring terminals.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention pre-attaches the terminal plate to the case in a fixed position during assembly, establishing a stable reference point for electrical connection before any operation occurs. This preliminary fixation ensures that the terminal plate maintains its intended position and electrical contact geometry throughout the device's operational life, preventing the position deviation and contact instability that would occur with movable spring terminals.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the back cover is designed to be frequently opened and closed for battery exchange and maintenance, then ease of operation is improved, but the contact portion of the terminal plate experiences increased abrasion and functionality degradation

Engineering Contradiction:
Improveaccessibility for battery exchangeVSAvoidcontact stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention separates the back cover into distinct functional zones: a movable back cover portion for frequent access and a fixed terminal plate portion for stable electrical connection. This segmentation allows the back cover to be opened and closed freely for maintenance while the terminal plate remains stationary, eliminating the wear and contact instability that would result from a unified movable structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The terminal plate acts as an intermediary component that bridges the fixed case and the movable back cover. It provides a stable electrical connection point that is not directly involved in the opening/closing motion, thereby mediating between the conflicting requirements of movability for maintenance and stability for electrical connection.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4560414A1Electronic device and electronic timepiece
Publication Date: 2025.05.28 CASIO COMPUTER CO LTD
  • EP4560414A1 patent drawingFigure 1
  • EP4560414A1 patent drawingFigure 2
  • EP4560414A1 patent drawingFigure 3~4

AI summary

Disclosed an electronic device, including: a metal component that is externally mounted to a case; a metal plate that is provided inside of a case back-surface side and functions as GND; and an internal terminal plate that is provided inside the case and causes the metal component to be connected to the metal plate. The internal terminal plate is sandwiched between the case and the metal plate.