Sheet Reversing Apparatus for Duplex Printing Jam Prevention

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Solution Overview

Problem

Existing image forming apparatuses, such as printers, face issues with detecting sheets stored in the reversing space portion during duplex printing, leading to potential damage when undetected sheets interact with subsequent print operations due to curling or skew feeding, especially for small-sized sheets outside the detection area.

Innovation Solution

A sheet reversing apparatus with a reversing roller pair, support portion, and first detection portion that conveys sheets in reverse, using a control system to ensure continuous forward conveyance until the final sheet is detected, preventing abnormality-induced sheet jams and ensuring proper nipping to prevent damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a detection portion is provided in the reversing space portion to detect stored sheets, then sheet detection capability is improved, but detection reliability deteriorates when sheets are stored outside the detection area (e.g., small-sized sheets, curled sheets, or skew-fed sheets)

Engineering Contradiction:

Improvesheet detection capabilityVSAvoiddetection reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

Instead of trying to detect all sheets in the reversing space portion (which fails for sheets outside the detection area), the invention inverts the approach: it uses the reversing roller pair to actively push sheets toward the detection portion, ensuring sheets are positioned within the detectable area through mechanical action rather than passive detection

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The reversing roller pair acts as an intermediary between the stored sheets and the detection portion. By pushing sheets toward the detection area, it mediates the interaction between sheets that are difficult to detect (due to size, curling, or skew) and the detection system, enabling reliable detection without expanding the detection area

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the reversing roller pair conveys sheets in reverse for duplex printing, then printing functionality is improved, but sheet damage risk increases when undetected sheets remain in the reversing space portion

Engineering Contradiction:

Improveduplex printing functionalityVSAvoidsheet damage risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary action by pushing sheets toward the detection portion before the next printing operation begins. The control portion activates the reversing roller pair to convey sheets forward until detection occurs, ensuring the reversing space portion is clear of undetected sheets that could cause damage during subsequent printing

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control portion uses feedback from the detection portion to determine when sheets have been successfully detected and positioned. The system continuously monitors detection status and adjusts the reversing roller pair operation accordingly, stopping only when sheets are confirmed to be in the detection area, thereby preventing sheet damage

Inventive Principle:

Principle #23Feedback

3Device complexity

If the detection portion is positioned in a fixed location in the reversing space portion, then device complexity is reduced, but detection coverage deteriorates for sheets stored outside the detection area

Engineering Contradiction:

Improvedetection system complexityVSAvoiddetection area coverage

Core Design Contradiction:

Device complexityVSArea of stationary object

Solution Approach 1:

Instead of making the detection portion movable (which would increase complexity), the invention makes the sheets dynamic by using the reversing roller pair to actively convey them toward the fixed detection portion. This dynamic sheet positioning approach maintains simple device architecture while achieving comprehensive detection coverage

Inventive Principle:

Principle #15Dynamics

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

Prevents sheet damage by reliably detecting and managing sheets in the reversing space, ensuring smooth operation and maintaining print quality by preventing undetected sheets from interfering with subsequent printing processes.

Implementation Method 1

a reversing roller pair that, after conveying a sheet in a forward direction while the sheet is in a nipped state, is configured to convey the sheet in reverse by conveying the sheet in an opposite direction opposite to the forward direction

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12162713B2Sheet reversing apparatus and image forming apparatus

Publication Date: 2024.12.10 CANON KK

AI summary

A reversing roller pair is controlled such that, when an abnormality occurs during the conveying of a sheet, the sheet is conveyed in a forward direction by the reversing roller pair, and is controlled to continue conveying until a state where the final sheet among the sheets conveyed in the forward direction is detected by a first detection portion, and subsequently to stop in a state where the final sheet is nipped by the reversing roller pair.