Chair Automatic Lock Mechanism Using Weight-Sensing Control

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Solution Overview

Problem

Conventional chairs lack a mechanism to automatically lock and unlock the movement of the back and seat independently without manual operation, leading to instability and discomfort, especially when the seated person leaves or sits, and existing solutions are either cumbersome or unsuitable for various seating configurations.

Innovation Solution

A chair with a control mechanism that detects the seating state through the height change of a weight-receiving part, mechanically controlling the movable parts to allow or suppress movements like tilting, swinging, or rolling without requiring seat movement, using an engagement system with elastic members to automatically switch states based on the presence or absence of a seated person.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a movable part is introduced in a chair to allow the back and seat to move to appropriate positions, then the ease of operation is improved, but the stability deteriorates when the seated person leaves the seat

Engineering Contradiction:
Improveease of operationVSAvoidstability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The control mechanism performs preliminary action by automatically locking the movable part when the seated person leaves the seat. The detection mechanism detects the absence of the seated person and triggers the locking mechanism in advance to prevent instability, without requiring manual intervention.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The chair performs self-service through the automatic control mechanism that detects the seating state and autonomously locks or unlocks the movable part. The system serves itself by using the detection mechanism to trigger the locking mechanism without external human operation.

Inventive Principle:
Principle #25Self-service

2Stability of the object's composition

If a mechanical restriction mechanism is configured to automatically lock the movable part when the seated person leaves, then the stability is improved, but the device complexity increases

Engineering Contradiction:
ImprovestabilityVSAvoiddevice complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The control mechanism merges the detection mechanism and locking mechanism into an integrated system. The detection mechanism detects the seating state and directly triggers the locking mechanism through a connected control mechanism, combining multiple functions into a unified structure to reduce overall complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The control mechanism serves multiple functions: it detects the seating state, determines whether to lock or unlock, and controls the locking mechanism. This multi-functional design reduces the need for separate components and simplifies the overall system structure.

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

3Ease of operation

If the movable part is unlocked automatically when the person sits on the seat, then the ease of operation is improved, but the reliability deteriorates due to potential failure in automatic unlocking

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The detection mechanism provides feedback about the seating state to the control mechanism. When the seated person is detected, the feedback triggers the unlocking mechanism to automatically unlock the movable part, ensuring reliable operation based on real-time detection.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control mechanism performs preliminary unlocking action when the seated person approaches or sits on the seat. The detection mechanism detects the presence and triggers the unlocking mechanism in advance to ensure the movable part is ready for use, improving both ease of operation and reliability.

Inventive Principle:
Principle #10Preliminary action

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

Enables easy, comfortable, and secure operation of the chair by automatically locking or unlocking movements without manual intervention, suitable for various seating preferences and configurations, ensuring stability and ease of use.

Implementation Method 1

an engaging part provided on another of the movable part and the support part, wherein an elastic member biases the engaged part in a direction in which the engaged part engages with the engaging part

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3643206B1chair
Publication Date: 2024.09.04 KOKUYO CO LTD
  • EP3643206B1 patent drawingFigure 1
  • EP3643206B1 patent drawingFigure 2
  • EP3643206B1 patent drawingFigure 3

AI summary

[Problem] Provided is a chair capable of changing an operation of a movable part between allowed and suppressed states, without causing an up-down movement of a seat or without requiring a complicated structure relying on a back. [Solution] For that purpose, a weight-receiving part 50, the height position of which changes due to a person sitting on a seat surface, is provided on a seat 5, the change of the height position is mechanically transmitted to a control mechanism 8X configured to control an operation of a front-rear swing part 3 being the movable part, and the control mechanism 8X changes an operation of the front-rear swing part-3 being the movable part between allowed and suppressed states.