Toner Cartridge Latching with Cam-Guided Unit Separation

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Solution Overview

Problem

The removal of both the toner cartridge and imaging unit from an image forming device can be cumbersome for users, leading to potential damage due to user carelessness or inattention, and requires both units to be set down, complicating access to the device's inner area for error correction.

Innovation Solution

A first replaceable unit with a latch mechanism that allows for easy attachment and detachment from a second replaceable unit, featuring a latch that moves between latching and unlatching positions, guided by cam follower surfaces to ensure secure attachment and easy separation, without the need for biasing members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If both the toner cartridge and imaging unit are removed for error correction access, then the user can access the inner area of the device, but the operation becomes cumbersome and increases the risk of damage due to user carelessness

Engineering Contradiction:
Improveease of access to inner areaVSAvoidrisk of damage
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention divides the replaceable units into a first replaceable unit (toner cartridge) and a second replaceable unit (imaging unit), each with independent latch mechanisms. This segmentation allows selective removal of only the necessary unit for error correction, rather than requiring removal of both units, thereby reducing operational complexity and minimizing the risk of damage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The latch mechanism incorporates cam follower surfaces that dynamically guide the latch between latching and unlatching positions during mating and separation operations. This dynamic guidance ensures controlled movement and engagement, preventing accidental disengagement or damage while maintaining ease of operation.

Inventive Principle:
Principle #15Dynamics

2Reliability

If a latch mechanism is used to secure the toner cartridge to the imaging unit, then secure attachment is achieved, but the device complexity increases

Engineering Contradiction:
Improvesecure attachmentVSAvoidlatch mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The latch mechanism is designed to automatically engage and disengage through the cam follower surfaces during the natural mating and separation movements of the replaceable units. The cam surfaces guide the latch transitions without requiring additional actuators, motors, or complex control systems, thereby achieving secure attachment while minimizing device complexity.

Inventive Principle:
Principle #25Self-service

3Reliability

If the latch is positioned on the rear of the housing away from the outlet, then secure latching is achieved, but the user must access the rear area for manual unlatching

Engineering Contradiction:
Improvesecure latchingVSAvoidease of manual unlatching
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The cam follower surfaces act as intermediaries that translate the user's simple pulling motion at the front of the device into the complex rotational movement required to disengage the latch at the rear. This intermediary mechanism allows users to unlatch the secure connection without directly accessing or manipulating the rear latch area.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4073591B1Toner cartridge latching
Publication Date: 2025.09.17 LEXMARK INTERNATIONAL INC
  • EP4073591B1 patent drawingFigure 1
  • EP4073591B1 patent drawingFigure 2
  • EP4073591B1 patent drawingFigure 3

AI summary

A first replaceable unit is provided for use with a second replaceable unit in an electrophotographic image forming device. The first replaceable unit includes a latch movable between a latching position for latching the first replaceable unit to the second replaceable unit and an unlatching position for permitting the first replaceable unit to separate from the second replaceable unit. The latch is positioned to contact a latch catch on the second replaceable unit in order to prevent the first replaceable unit from separating from the second replaceable unit when the first replaceable unit is mated with the second replaceable unit and the latch is in the latching position. The latch includes a cam follower surface for contacting a camming surface on the second replaceable unit during mating of the first replaceable unit with the second replaceable unit to cause the latch to move toward the latching or unlatching position.