Image Forming Apparatus Velocity Control for Color Registration

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Solution Overview

Problem

Existing image forming apparatuses face significant color misregistration issues due to velocity fluctuations between photosensitive drums and intermediate transfer media, caused by mechanical errors and friction torque variations, which are not effectively controlled by existing methods.

Innovation Solution

The apparatus controls the peripheral velocity difference between the image bearing member and the intermediate transfer medium by setting it to a predetermined value at the start and increasing it only when minute toner reaches the primary transfer unit, using a control unit to manage the drive motors and maintain stable motor torques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the peripheral velocity difference between the photosensitive drum and intermediate transfer medium is set to zero to prevent image expansion and contraction, then image quality is improved, but velocity fluctuations occur due to mechanical shape errors and friction torque variations, causing color misregistration

Engineering Contradiction:

Improveimage qualityVSAvoidvelocity stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes the peripheral velocity difference parameter from zero to a predetermined non-zero value. By setting the photosensitive drum's peripheral velocity to be slightly higher than the intermediate transfer medium's velocity, the system compensates for friction torque variations and mechanical errors, thereby maintaining both image quality and velocity stability simultaneously.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the peripheral velocity of the photosensitive drum is set to be higher than the intermediate transfer medium to generate one-way friction torque and control color misregistration, then velocity fluctuation is reduced, but the driving torque of the motor decreases when minute toner reaches the primary transfer unit, causing sharp velocity changes

Engineering Contradiction:

Improvevelocity stabilityVSAvoidmotor driving torque

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent introduces dynamic control by adjusting the peripheral velocity difference based on the transfer state. When minute toner reaches the primary transfer unit, the system temporarily increases the peripheral velocity difference to maintain stable friction torque and prevent sharp velocity changes, thereby ensuring continuous stable operation without sacrificing motor driving torque.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the peripheral velocity difference is increased to maintain stable friction torque during image formation, then velocity fluctuations are reduced, but the peripheral velocity of the slower component is greatly fluctuated for a while, causing color misregistration

Engineering Contradiction:

Improvefriction torque stabilityVSAvoidcolor registration

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies partial action by temporarily increasing the peripheral velocity difference only when necessary (when minute toner reaches the primary transfer unit) rather than maintaining it continuously. This controlled partial increase stabilizes friction torque during critical periods while minimizing overall velocity fluctuations that would cause color misregistration.

Inventive Principle:

Principle #16Partial or excessive 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

This approach reduces velocity fluctuations and prevents color misregistration by minimizing friction torque variations, ensuring consistent image formation and improved imaging quality.

Implementation Method 1

a development unit configured to develop the latent image to form a toner image

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 2

friction torque will occur between the photosensitive drum and the intermediate transfer medium

Methodology Applied

Scientific EffectFriction torque: Friction

Implementation Method 3

the superimposed toner images that are primarily transferred to the intermediate transfer medium are secondarily transferred to a sheet

Methodology Applied

Scientific EffectFriction torque: Friction

Data Source

PatentUS9389546B2Image forming apparatus with intermediate toner transfer medium, control method therefor, and storage medium storing control program therefor

Publication Date: 2016.07.12 CANON KK

AI summary

An image forming apparatus that is capable of reducing velocity fluctuation due to variation of friction torque between an image bearing member and an intermediate transfer medium depending on a toner image. An exposure unit forms a latent image on the image bearing member rotated by a first drive unit. A development unit develops the latent image to form a toner image. A primary transfer unit transfers the toner image to an intermediate transfer medium rotated by a second drive unit. A secondary transfer unit transfers the toner image to a sheet. A control unit controls the drive units so that a peripheral velocity difference between the image bearing member and the intermediate transfer medium becomes a first value at starting, and controls so that the peripheral velocity difference becomes a second value larger than the first value when minute toner reaches the position of the primary transfer unit.