Substrate-Free Buckle Switch Structure for Compact Latch Detection

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Solution Overview

Problem

Existing seat belt buckle switches have a large volume due to the inclusion of a substrate with a magnetic sensor, which increases the overall size of the buckle.

Innovation Solution

The buckle switch integrates a magnetic sensor directly onto a synthetic resin mold without a substrate, with a movable magnet and ejector mechanism to detect tongue insertion, reducing the volume by eliminating the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a substrate is used to mount the magnetic sensor in the buckle switch, then the magnetic sensor can be properly supported and connected, but the volume of the buckle switch and buckle increases

Engineering Contradiction:
Improvemagnetic sensor support and connectionVSAvoidbuckle switch volume
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The invention extracts and eliminates the substrate from the buckle switch structure. Instead of mounting the magnetic sensor on a substrate, the sensor is directly integrated into the housing, removing the unnecessary component and reducing overall volume while maintaining functional integrity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the magnetic sensor mounting function directly into the housing structure. The housing simultaneously serves as both the structural enclosure and the sensor mounting platform, eliminating the need for a separate substrate and reducing the number of parts

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If a substrate is included in the buckle switch structure, then the magnetic sensor can be properly positioned, but the overall buckle size becomes large

Engineering Contradiction:
Improvemagnet position detectionVSAvoidbuckle volume
Core Design Contradiction:
Measurement precisionVSVolume of stationary object

Solution Approach 1:

The substrate is extracted from the structure, and the housing directly provides the positioning function. The magnetic sensor is mounted directly on the housing with precise positioning features that eliminate the need for a separate substrate while maintaining detection accuracy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The housing is designed to serve multiple functions: it encloses the magnetic sensor, provides structural support, and enables precise positioning of the sensor relative to the magnet. This multi-functionality eliminates the need for a separate substrate while maintaining measurement precision

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 allows for a compact buckle switch and buckle design, reducing the overall volume while maintaining functionality.

Implementation Method 1

a magnetic sensor that detects a latch in response to magnetic flux of a magnet moving accompanying tongue insertion

Methodology Applied
Scientific EffectMagnetic flux detection: Magnetic Field

Data Source

PatentEP3780058B1Buckle switch and buckle
Publication Date: 2023.09.13 JOYSON SAFETY SYST JAPAN KK
  • EP3780058B1 patent drawingFigure 1
  • EP3780058B1 patent drawingFigure 2
  • EP3780058B1 patent drawingFigure 3

AI summary

A buckle switch 20 includes a magnetic sensor for detecting the latch of a tongue plate 6. The magnetic sensor is installed inside a sensor chip 21. The sensor chip 21 is disposed above a synthetic-resin base mold 31. A top mold 32 is formed by insert molding. There is no circuit substrate in the buckle switch 20.