Printer Sheet Stacking With Reprint Order Recovery

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Solution Overview

Problem

Existing sheet printers face issues with maintaining image order when removing deviating sheets, leading to media waste and reduced productivity due to the disruption of the sheet order in the stack.

Innovation Solution

The method involves splitting the stream of sheets around the deviating sheets, directing upstream sheets to a first stack holder and downstream sheets to a second holder, reprinting missing images on re-print sheets, and integrating these into the stack to maintain image order, while minimizing sheet removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If deviating sheets are removed from the transport path, then image quality is improved, but sheet order is disrupted and media waste increases

Engineering Contradiction:
Improveimage qualityVSAvoidmedia waste
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The stream of sheets is segmented into three portions: upstream sheets (directed to first stack holder), the deviating sheet (removed), and downstream sheets (directed to second stack holder). This segmentation allows selective removal of only the deviating sheet while maintaining order in the remaining sheets, reducing media waste compared to removing multiple sheets.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Re-print sheets act as intermediaries to restore the image order. The controller schedules images for the removed deviating sheet to be printed on re-print sheets, which are then inserted into the stack at the appropriate position. This intermediary mechanism maintains image order without requiring removal of additional sheets.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If multiple sheets are directed to the reject collector to restore image order, then image order is maintained, but media waste increases

Engineering Contradiction:
Improveimage orderVSAvoidmedia waste
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

Instead of discarding multiple sheets to restore image order, the system creates copies of the necessary images on re-print sheets. The controller identifies which images are missing from the stack due to sheet removal and schedules these images to be printed on re-print sheets, which are then inserted at the correct positions. This copying approach maintains image order while minimizing media waste.

Inventive Principle:
Principle #26Copying

3Manufacturing precision

If deviating sheets are removed upstream of stack holders, then image quality is improved, but productivity decreases due to re-scheduling

Engineering Contradiction:
Improveimage qualityVSAvoidproductivity
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The controller performs preliminary scheduling of re-print sheets and their corresponding images immediately when a deviating sheet is detected. Rather than waiting until the end of the print job, the system proactively plans the re-print operations and integrates them into the existing print schedule, minimizing disruptions and maintaining productivity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system maintains continuous operation by seamlessly integrating re-print operations into the existing print workflow. Re-print sheets are inserted into the stream and processed through the printer without stopping the overall printing process. The stacker continuously receives sheets from both the main stream and re-print sheets, ensuring uninterrupted stacking and maintaining productivity.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP4582363A1A method of stacking printed sheets in a printer
Publication Date: 2025.07.09 CANON KK
  • EP4582363A1 patent drawingFigure 1~2
  • EP4582363A1 patent drawingFigure 3~4
  • EP4582363A1 patent drawingFigure 5~6

AI summary

A productive method of stacking sheets (A1-A14) which minimizes media waste is provided, which method comprising the steps of: - removing at least one selected sheets (A1-A14) from a stream of sheets (A1-A14) designated for forming a stack with a queue of images (F1-F12, B1-B12) thereon in a predetermined image order: - directing sheets (A1-A14) upstream of the at least one selected sheet (A1-A14) in the stream to a first stack holder (54) to stack these according to predetermined image order; - directing sheets (A1-A14) downstream of the at least one selected sheet (A1-A14) in the stream to a second stack holder (70) different from the first stack holder (54) to stack these according to the predetermined image order; - printing the one or more images for the selected sheets (A1-A14) on at least one re-print sheet (A1-A14) added to the stream and directing the printed at least one re-print sheet (A1-A14) to the first stack holder (54), so that the at least one re-print sheet (A1-A14) is stacked on the previously stacked sheet (A1-A14) according to the image order.