Cam Phase Asymmetry for Transfer Device Load Reduction

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Solution Overview

Problem

The existing electrophotographic image forming apparatus experiences increased cam driving load during mode conversion between ready, mono, and color modes, leading to higher motor capacity requirements, increased costs, and reduced lifespan and reliability of the mode conversion device due to simultaneous friction loads from cams with the same phase.

Innovation Solution

The apparatus incorporates first and second cam members with different top dead center phases, allowing the first slider members to complete their movement before the second slider members, thereby separating the driving loads and using a sensing unit with an indicating member to accurately recognize mode positions and control motor operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If cams with the same phase are used to simultaneously move multiple sliders, then mode conversion is achieved, but cam driving load increases due to simultaneous friction loads

Engineering Contradiction:
Improvemode conversionVSAvoidcam driving load
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The patent applies asymmetry by configuring different cam members with different phases relative to each other. Specifically, the first cam member has a different phase than the second cam member, causing them to reach their top dead centers at different times. This phase difference creates an asymmetric timing pattern that separates the friction load peaks, preventing them from overlapping and thus reducing the total cam driving load while still achieving mode conversion between ready, mono, and color modes.

Inventive Principle:
Principle #4Asymmetry

2Adaptability or versatility

If cam driving load is increased, then mode conversion function is achieved, but motor capacity must be increased raising costs and set size

Engineering Contradiction:
Improvemode conversion functionVSAvoidmotor capacity
Core Design Contradiction:
Adaptability or versatilityVSPower

Solution Approach 1:

The patent reduces motor capacity requirements by introducing asymmetric phase relationships between cam members. The first cam member and second cam member are configured with different phases, which distributes the driving load more evenly over time. This prevents peak load accumulation and allows the use of a smaller motor while maintaining the full mode conversion function between ready, mono, and color modes.

Inventive Principle:
Principle #4Asymmetry

3Ease of operation

If cams with same phase are used, then mode conversion is achieved, but lifespan of mode conversion device is reduced due to increased friction and wear

Engineering Contradiction:
Improvemode conversionVSAvoidlifespan of mode conversion device
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent extends the lifespan of the mode conversion device by configuring cam members with different phases. This asymmetric arrangement ensures that the friction loads from different cam-slider interactions do not occur simultaneously, reducing cumulative wear and thermal stress on the mechanical components. The phase-differentiated cam members distribute operational stress more evenly over time, enhancing reliability and extending service life while maintaining mode conversion capability.

Inventive Principle:
Principle #4Asymmetry

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 reduces the total cam driving load, improves mode conversion accuracy, extends the lifespan of the transfer device, and enhances reliability by allowing the use of a smaller motor capacity, reducing costs and improving image quality.

Implementation Method 1

first cam members moving the first slider members and second cam members moving the second slider members

Methodology Applied
Scientific EffectCam mechanism: Cam

Data Source

PatentEP2600204B1Transfer device and image forming apparatus having the same
Publication Date: 2020.08.12 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP2600204B1 patent drawingFigure 1
  • EP2600204B1 patent drawingFigure 2
  • EP2600204B1 patent drawingFigure 3

AI summary

A transfer device and an image forming apparatus having the same are provided. Shapes of cam profiles of first cam members and second cam members controlling movement of first slider members moving a first transfer roller corresponding to a black developer, and second slider members moving a second transfer roller corresponding to a color developer. Times are different as when movement of the first slider members is completed and when movement of the second slider members is completed in mode conversion among a ready mode, a mono mode and a color mode, and thus a driving load generated when the first and second cam members are rotated is reduced, non-uniformity of the rotating speeds of the first and second cam members is reduced, and problems generated due to non-uniform rotating speeds of the cam members are reduced.