Booklet Page Alignment Using Trailing-Edge Sheet Detection

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Solution Overview

Problem

Existing image forming technologies face challenges in aligning image positions accurately on facing pages of a booklet, leading to misalignments when viewed in an open spread.

Innovation Solution

An image forming apparatus with a detection unit to identify leading and trailing edges of sheets, an alignment unit to correct image positions based on edge detection, and a reversing unit to reverse sheets for accurate alignment, ensuring that the trailing edge of one sheet aligns with the leading edge of the next sheet during image formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If image positions are aligned based on leading edge detection only, then the alignment process is simple, but misalignments occur on facing pages in open spread mode

Engineering Contradiction:

Improvealignment process complexityVSAvoidimage position alignment accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The system performs preliminary detection of both leading and trailing edges of the first sheet before forming the second image. The trailing edge detection result is obtained in advance and used to correct the alignment of the second image, ensuring accurate positioning on facing pages before the actual image formation occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the trailing edge detection of the first sheet to adjust and correct the position of the second image. The detected trailing edge position provides feedback information that is fed back into the alignment control system to compensate for misalignments and achieve precise image positioning on facing pages.

Inventive Principle:

Principle #23Feedback

2Productivity

If sheets are reversed for two-sided printing, then both sides can be utilized, but misalignments occur between front and back surface images

Engineering Contradiction:

Improvesheet utilization efficiencyVSAvoidimage position alignment between facing pages

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system replaces purely mechanical alignment methods with a detection and correction system. Instead of relying solely on physical sheet handling and mechanical positioning, the invention uses detection units to measure trailing edge positions and electronically corrects image positions based on detected deviations, achieving higher precision in two-sided printing alignment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If alignment is performed without trailing edge detection, then the process is faster, but image position misalignments occur on facing pages

Engineering Contradiction:

Improveimage formation speedVSAvoidimage position alignment accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12468248B2Image forming apparatus

Publication Date: 2025.11.11 CANON KK

AI summary

An image forming apparatus includes an image forming unit, a reversing unit, a detection unit for detecting leading and trailing edges of a sheet, and an alignment unit for aligning an image with respect to the leading edge of the sheet, and generates an output item in which a first sheet with a first image and a second sheet with a second image are stacked, a surface with the first image of the first sheet and a surface with the second image of the second sheet face each other, and a trailing edge of the first sheet and a leading edge of the second sheet face each other. The alignment unit corrects a position of the second image with respect to the leading edge of the second sheet during formation of the second image based on a detection result of the trailing edge of the first sheet.