Image Forming System with Contact-Free Shading Reference Plates

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Solution Overview

Problem

Existing image reading systems face issues with shading correction accuracy due to the placement of white reference plates on the conveyance path, which can cause sheet peeling, staining, and paper jams, leading to reduced reading accuracy.

Innovation Solution

The system arranges white reference plates on the surface of the reading glass upstream of the reading position to avoid contact with the sheet, using a staggered configuration to minimize space and cost, and employs a sheet guide member to prevent jams while maintaining shading correction accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the white reference plate is provided on the conveyance path, then shading correction can be performed, but the sheet may be rubbed by the white reference plate causing image peeling and staining

Engineering Contradiction:
Improveshading correction accuracyVSAvoidsheet rubbing and staining
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The white reference plate is moved from the conveyance path (2D plane) to the reading glass surface (3D space above the conveyance path). This spatial relocation allows the reference plate to remain accessible for shading correction while eliminating direct contact with the sheet during conveyance, thus preventing rubbing and staining.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The reading glass serves as an intermediary surface that holds the white reference plate. Instead of placing the reference plate directly on the conveyance path where it would contact the sheet, the reading glass acts as a mediator to position the reference plate in a location that is both functional for shading correction and harmless to the sheet.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the white reference plate is provided on the conveyance path, then shading correction can be performed, but the leading end of the sheet may contact the white reference plate causing buckling and paper jam

Engineering Contradiction:
Improveshading correction accuracyVSAvoidpaper jam prevention
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

By positioning the white reference plate on the reading glass surface rather than on the conveyance path, the reference plate is elevated to a different spatial dimension. This prevents the sheet's leading end from making contact with the reference plate during conveyance, eliminating the risk of buckling and paper jams while preserving shading correction functionality.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Object-affected harmful factors

If the white reference plate is placed on the reading glass, then sheet contact is avoided, but space and cost may increase

Engineering Contradiction:
Improvesheet contact preventionVSAvoidspace and cost
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The reading glass serves multiple functions: it is used for sheet reading and also serves as a mounting surface for the white reference plate. This multi-functional use eliminates the need for additional dedicated space or components for housing the reference plate, thereby avoiding increased device complexity and cost.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The function of the reading glass is merged with the function of supporting the white reference plate. Instead of having separate components for sheet reading and reference plate storage, the design combines these functions into a single integrated structure, reducing overall space requirements and component count.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This arrangement enhances shading correction accuracy by preventing sheet contact with the white reference plates, reducing jams, and maintaining consistent image reading quality.

Implementation Method 1

an image reading apparatus configured to read an image of a sheet through a transparent member through use of an image sensor

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

shading correction is performed by reading a white reference plate through use of an image sensor in order to correct light amount unevenness of a light source

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3916484B1Image forming system
Publication Date: 2025.07.09 CANON KK
  • EP3916484B1 patent drawingFigure 1
  • EP3916484B1 patent drawingFigure 2
  • EP3916484B1 patent drawingFigure 3

AI summary

An image forming system including: a conveyance unit configured to convey a first sheet on which an image has been formed by an image forming portion; a reading unit including a reading sensor configured to read the first sheet being conveyed by the conveyance unit through a transparent member at a reading position; a guide member configured to cover a reference member on a side opposite to the reading sensor with respect to the transparent member; and a controller configured to perform shading correction on a result of reading the first sheet based on image data obtained by the reading unit reading the reference member through the transparent member, and to control, based on an image subjected to the shading correction, a geometric characteristic of an image to be formed on a second sheet by the image forming portion.