Rolled-Medium Image Forming Apparatus With Two-Stage Conveyance

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Solution Overview

Problem

Conventional image forming apparatuses experience reduced print throughput due to the need to return paper to the print start position after cutting, especially when during-printing cutting is employed, leading to standby times during the transition between pages.

Innovation Solution

The image forming apparatus optimizes paper conveyance by dividing the process into two stages: an initial conveyance to a predetermined position after completing one page printing, followed by a second conveyance to the final print start position, allowing simultaneous data creation for the next page, thus reducing standby times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If paper is conveyed to a predetermined position after completing one page printing before settling the print start position of the next page, then print throughput is improved by reducing standby time, but paper conveyance control complexity increases

Engineering Contradiction:
Improveprint throughputVSAvoidpaper conveyance control complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The paper conveyance unit performs a preliminary conveyance operation to bring the paper to a predetermined position (such as the cutter position or a position near the print start position) immediately after completing printing of one page. This preliminary action is executed before the control unit settles the final print start position of the next page, thereby reducing the standby time and improving print throughput while maintaining manageable control complexity through automated sequencing

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The paper conveyance process is segmented into multiple stages: (1) initial conveyance to a predetermined position after page completion, (2) settlement of the print start position for the next page, and (3) final conveyance to the exact print start position. This segmentation allows the system to perform useful work during what would otherwise be idle time, improving overall productivity without overwhelming the control system

Inventive Principle:
Principle #1Segmentation

2Productivity

If during-printing cutting is employed to eliminate paper returning operation, then print throughput is improved, but standby time occurs during the transition between pages

Engineering Contradiction:
Improveprint throughputVSAvoidstandby time between pages
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The system performs preliminary paper conveyance to a predetermined position (such as the cutter position) immediately after completing printing of one page, before the print start position of the next page is settled. This preliminary action eliminates the need for paper returning operations while minimizing standby time by keeping the paper in a ready position for the next printing operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The paper conveyance unit continues to perform useful conveyance operations during the transition between pages rather than idle standby. By continuously moving the paper to predetermined positions and preparing it for the next page, the system eliminates wasted time while maintaining the benefits of during-printing cutting

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP3871891B1Image forming apparatus
Publication Date: 2025.09.03 CANON KK
  • EP3871891B1 patent drawingFigure 1
  • EP3871891B1 patent drawingFigure 2
  • EP3871891B1 patent drawingFigure 3

AI summary

Print throughput is improved in a case where an image forming apparatus prints multiple pages on a rolled printing medium. An image print apparatus (4) is capable of printing multiple pages on a rolled printing medium, and includes a conveyance unit (104) that conveys a printing medium (101), a printing unit that prints on the printing medium, and a cutting unit that cuts out the printing medium. The conveyance unit performs a first conveyance operation (612) to convey the printing medium by a predetermined length in a direction to discharge the printing medium and to stop the conveyance, which is carried out after completion of printing of one page and before settlement of a print start position (g) of the next page, and a second conveyance operation (613) including an operation to convey the printing medium in the direction to discharge until the print start position reaches a position of the printing unit, which is carried out after settlement of the print start position of the next page.