Extension Ladder Locking Device with Visual Status Indicator

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Solution Overview

Problem

Existing extension ladders lack visibility of the locking pin's insertion status into locking holes, leading to safety concerns due to potential accidental unfolding when users cannot confirm the ladder is locked, especially with lower rungs being obstructed and harder to access.

Innovation Solution

An extension ladder with a ladder leg locking device featuring a locking pin, control member, indication member, and display member, where the indication member moves to indicate on display areas whether the ladder legs are locked or unlocked, providing visual confirmation through color-coded areas on the rung.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the locking pin is located inside the rung, then the structure is compact and simple, but the user cannot see whether the locking pin has been accurately inserted into the locking holes

Engineering Contradiction:
Improvestructure simplicityVSAvoidlocking status visibility
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The patent introduces an indication member as an intermediary element that visually represents the locking status. The indication member is connected to the locking pin mechanism and provides visual feedback through color-coded display areas, allowing users to confirm locking status without direct line of sight to the locking pin itself.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs color-coded display areas on the indication member to represent different locking states. Different colors indicate whether the locking pin is properly inserted or not, providing intuitive visual information to users about the locking status without requiring them to see the actual locking pin position.

Inventive Principle:
Principle #32Color changes

2Device complexity

If the button is positioned on lower rungs, then the locking mechanism is compact, but the button cannot be seen due to obstruction and distance

Engineering Contradiction:
Improvemechanism compactnessVSAvoidbutton visibility and accessibility
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The patent transitions the visual feedback from a three-dimensional button that requires direct viewing to a two-dimensional color-coded display area on the indication member. This dimensional change allows the status indication to be viewed from various angles and distances, improving visibility without increasing the mechanism's footprint.

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

Solution Approach 2:

The indication member serves as an intermediary that translates the mechanical locking state into visible visual information. This mediator allows users to assess locking status from a distance and at various angles without needing direct line of sight to the actual locking components.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If no visual indication is provided, then the device is simple, but the user cannot confirm whether the ladder is locked safely

Engineering Contradiction:
Improvedevice simplicityVSAvoidsafety confirmation
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements a visual feedback system where the indication member provides immediate visual confirmation of the locking status. The color-coded display areas give users real-time feedback about whether the locking pin is properly inserted, enabling them to confirm safe locking before using the ladder.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent uses color-coded display areas to provide clear visual feedback about locking status. Different colors indicate different states (locked/unlocked), giving users immediate and unambiguous confirmation of whether the ladder is safely locked without adding complex mechanical verification mechanisms.

Inventive Principle:
Principle #32Color changes

Data Source

PatentEP3613936B1Ladder post locking device for extension ladder
Publication Date: 2022.03.30 GUANGDONG PRESTIGE TECHNOLOGY COMPANY LIMITED
  • EP3613936B1 patent drawingFigure 1
  • EP3613936B1 patent drawingFigure 2
  • EP3613936B1 patent drawingFigure 3

AI summary

A ladder post locking device (100) for an extension ladder comprises a latch pin (1), a button (2), an indication component (3), a display component (4) and an elastic member (5). The latch pin (1) is movably provided inside a rung (200) of an extension ladder. The button (2) is provided at the rung (200) and used to drive the latch pin (1) to perform a locking operation or an unlocking operation on an upper ladder post (301) and a lower ladder post (302) which are sleeved together. The display component (4) is fixed at an outer side of the rung (200) and has at least two display regions. The indication component (3) moves with a movement of the button (2) or the latch pin (1) to point to the corresponding display region. The ladder post locking device (100) for an extension ladder can indicate whether a ladder post of an extension ladder is locked or unlocked, thereby improving usage safety.