Roll Paper Rewinding Control for Accurate Print Restart

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Solution Overview

Problem

Existing image forming apparatuses often perform unnecessary reverse rotation conveyance during printing stops, leading to wasteful operations and inadequate starting positions for subsequent printing due to fixed and unsuitable rewinding distances.

Innovation Solution

The image forming apparatus employs a control method that dynamically adjusts the rewinding distance based on printing conditions, including the type of printing, presence of splice tapes, and print speed, to accurately resume printing from the trailing edge of the previous job, minimizing waste.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reverse rotation conveyance is always performed after printing stop, then the roll paper is rewound to a predetermined position, but wasteful operations are performed and the next printing cannot be started from the suitable position

Engineering Contradiction:
Improvepositioning accuracyVSAvoidprinting efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies dynamics by making the rewinding operation conditional rather than fixed. The control unit determines whether rewinding is necessary based on the current position of the roll paper and the requirements of the next printing job. This dynamic decision-making process eliminates unnecessary rewinding operations while ensuring accurate positioning when needed, thereby resolving the contradiction between positioning reliability and printing productivity

Inventive Principle:
Principle #15Dynamics

2Ease of manufacture

If fixed reverse rotation conveyance is performed, then the rewinding distance is predetermined, but the next printing cannot be started from the suitable position due to varying printing conditions

Engineering Contradiction:
Improvecontrol simplicityVSAvoidprinting condition adaptability
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent transforms the fixed rewinding distance into a dynamic, adjustable parameter. The control unit calculates the appropriate rewinding distance based on varying printing conditions such as print speed, paper size, and job requirements. This allows the system to adapt to different printing scenarios while maintaining straightforward control logic, resolving the contradiction between control simplicity and adaptability

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of rewinding distance from a fixed value to a variable that is adjusted according to printing conditions. The control unit modifies the rewinding distance parameter based on factors such as print speed, paper dimensions, and job specifications, enabling the system to adapt to various printing requirements while keeping the control mechanism relatively simple

Inventive Principle:
Principle #35Parameter changes

3Reliability

If reverse rotation conveyance is performed, then the roll paper is rewound, but wasteful operations occur and waste paper is generated due to inadequate positioning

Engineering Contradiction:
Improvepositioning accuracyVSAvoidwaste paper
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent uses dynamic positioning control to determine whether rewinding is actually needed before performing the operation. By assessing the current roll paper position and the start position required for the next job, the system avoids unnecessary rewinding that would generate waste paper. This dynamic approach maintains positioning accuracy while eliminating wasteful operations and reducing paper loss

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4369102B1Image forming apparatus, control method of image forming apparatus, and program
Publication Date: 2026.04.08 CANON KK
  • EP4369102B1 patent drawingFigure 1
  • EP4369102B1 patent drawingFigure 2
  • EP4369102B1 patent drawingFigure 3A

AI summary

The present invention provides an image forming apparatus (100), a control method of the image forming apparatus (100), and a recording medium that can suppress occurrence of a wasteful operation and perform a rewinding operation of an optimal amount. To this end, after stop of printing by the image forming apparatus (100), a print status at print start is obtained, and a rewinding distance of a roll paper (111) is set based on the obtained print status. Then, a paper conveyance unit performs rewinding conveyance (reverse rotation conveyance) based on the set rewinding distance.