Duplex Image Forming Apparatus for Ink-Related Sheet Curl Control

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Solution Overview

Problem

Existing image forming apparatuses face issues with sheet curling during duplex printing due to ink adherence, leading to potential contact with the ejection portion during image formation on the back surface, and existing solutions that only consider end portions may not adequately address curling in the center portion and result in unnecessary stop time prolongation.

Innovation Solution

The apparatus acquires adherence amount information for specific areas on the sheet surface, including the center and end portions, and sets a stop time based on this information to suppress curling and unnecessary stop time prolongation, using a control system to temporarily halt sheet conveyance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If conveyance of the sheet is temporarily stopped based on ink adherence amount at the end portion only, then unnecessary stop time is suppressed, but sheet curling at the center portion may not be adequately prevented

Engineering Contradiction:
Improvestop timeVSAvoidcurl suppression
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The image forming area is divided into multiple specific areas (center portion area and end portion area), and ink adherence amount is acquired separately for each area. This segmentation allows independent analysis of curl-prone regions, enabling precise stop time determination that addresses both center and end portion curling issues without unnecessary time prolongation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different specific areas of the sheet are evaluated based on their local ink adherence characteristics. The center portion area and end portion area are assessed independently, allowing the system to apply locally-appropriate stop time control that matches the actual curling risk in each region, rather than using a uniform approach.

Inventive Principle:
Principle #3Local quality

2Productivity

If duplex image forming processing is executed without stopping sheet conveyance, then productivity is improved, but sheet curling causes the sheet to contact the ejection portion

Engineering Contradiction:
Improveduplex processing speedVSAvoidsheet contact with ejection portion
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system acquires ink adherence amount information for specific areas before completing the duplex image forming process. Based on this preliminary assessment, the stop time is determined in advance, allowing the sheet conveyance to be stopped at the appropriate moment to prevent curling-induced contact with the ejection portion during back surface image formation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the acquired ink adherence amount information to dynamically determine the stop time. This feedback mechanism allows the control system to adjust the sheet conveyance stopping timing based on actual ink adherence conditions in specific areas, preventing sheet contact with the ejection portion while maintaining optimal productivity.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4620689A1Image forming apparatus capable of suppressing generation of curls in sheets, and image forming method
Publication Date: 2025.09.24 KYOCERA DOCUMENT SOLUTIONS INC
  • EP4620689A1 patent drawingFigure 1
  • EP4620689A1 patent drawingFigure 2
  • EP4620689A1 patent drawingFigure 3~4

AI summary

An image forming apparatus (100) includes an acquisition processing portion (61) and a stop processing portion (63). The acquisition processing portion (61) acquires, when duplex image forming processing is executed, adherence amount information related to an adherence amount of ink by image formation for each of a plurality of specific areas (R20) preset in an image forming area (R10) on a first surface of a sheet. The stop processing portion (63) temporarily stops, based on a stop time set based on a plurality of pieces of the adherence amount information, conveyance of the sheet after the image formation on the first surface of the sheet and before the image formation on the second surface of the sheet during the execution of the duplex image forming processing.