Sequential Developing Roller Movement for Image Forming Apparatus

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Solution Overview

Problem

Existing image forming apparatuses using the contact developing method face challenges such as shortened lifetime of photosensitive members due to wear, waste of developer, contamination, and image distortion caused by uneven contact of developing rollers, which also hinder the reduction of First Print Out Time (FPOT).

Innovation Solution

The apparatus is designed with first and second photosensitive members and corresponding developing members that move to contact and retracted positions in a specific order, with the first developing member moving to the contact position faster than the second, allowing for synchronized image formation while minimizing impact and distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the developing roller is moved slowly from the separated position to the contact position to suppress impact and image distortion, then image quality is maintained, but the First Print Out Time (FPOT) increases

Engineering Contradiction:

Improveimage qualityVSAvoidFirst Print Out Time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The developing roller is made movable between contact and separated positions, allowing dynamic adjustment of the roller position based on operational requirements. This enables the system to switch between contact developing (for image formation) and separated state (for reducing wear and FPOT), resolving the contradiction between image quality and response time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The developing roller is pre-positioned in the separated state before image formation begins. This preliminary positioning allows the system to minimize the time the roller needs to travel to the contact position, thereby reducing FPOT while still enabling controlled movement when needed for image formation.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the developing roller is kept in contact with the photosensitive member for a long time, then continuous image formation is enabled, but the lifetime of the photosensitive member decreases due to wear

Engineering Contradiction:

Improvecontinuous image formationVSAvoidlifetime of photosensitive member

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The developing roller alternates between contact and separated states periodically. During image formation, the roller contacts the photosensitive member; during non-print periods, the roller separates. This periodic action reduces cumulative wear while maintaining productivity during active printing operations.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the contact state of the developing roller based on operational needs. By making the roller movable between contact and separated positions, the system can minimize wear during non-print periods while ensuring continuous image formation capability when required.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the developing roller is separated from the photosensitive member during non-print periods, then wear and contamination are reduced, but the time to reach contact position increases

Engineering Contradiction:

Improvereduction of wear and contaminationVSAvoidtime to reach contact position

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

4Productivity

If multiple developing rollers are moved to contact positions simultaneously, then image formation efficiency is improved, but impact and image distortion increase

Engineering Contradiction:

Improveimage formation efficiencyVSAvoidimage distortion

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The simultaneous movement of multiple developing rollers is segmented into sequential movements. Each developing roller moves to its contact position in a controlled sequence rather than simultaneously, reducing impact and image distortion while maintaining overall image formation efficiency through coordinated timing.

Inventive Principle:

Principle #1Segmentation

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 effectively shortens the First Print Out Time while maintaining image quality by controlling the contact and separation of developing rollers, reducing wear and contamination, and optimizing the timing of image formation across multiple colors.

Implementation Method 1

contact developing method which performs developing in a state in which developing rollers are in contact with a photosensitive members

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

electrostatic latent image on the photosensitive member is developed

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentUS9134693B2Image forming apparatus with developing unit and control method therefor

Publication Date: 2015.09.15 CANON KK

AI summary

First and second developing members are moved to a developing position from a retracted position respectively in the order of a first developing member and a second developing member, and image forming is started by adhering toner to a first photosensitive member and a second photosensitive member in this order, and a period in which the first developing member moves from the retracted position to the developing position is shorter than a period in which the second developing member moves from the retracted position to the developing position.