Discharge Guide Projections for Sheet Stacking Sag

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Solution Overview

Problem

As the number of recording media stacked increases, the distance from discharge rollers to the stacker grows, leading to a higher likelihood of improper stacking due to sagging of the leading edge of the recording medium during discharge.

Innovation Solution

A medium discharge device comprising a discharge tray with a first pair of rollers forming a nip and a second pair of rollers, along with a discharge guide featuring projections that guide the medium, ensuring it is discharged in a wave shape to maintain stiffness and prevent sagging, thereby reducing improper discharge and stacking issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the number of recording media stacked on the stacker increases, then the stacker capacity is improved, but the distance from discharge rollers to the stacker increases causing sagging of the leading edge

Engineering Contradiction:
Improvenumber of recording media stackedVSAvoidproper stacking
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The discharge guide projections are positioned to preliminarily support and guide the leading edge of the recording medium before it reaches the stacker. This preliminary action prevents sagging during discharge by maintaining proper positioning from the outset, addressing the problem before it occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The discharge guide projections act as an intermediary element between the discharge rollers and the stacker. These projections provide intermediate support to the leading edge of the recording medium, preventing sagging that would otherwise occur over the increased distance caused by high stack levels.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Length of stationary object

If the distance from discharge rollers to the stacker increases, then more media can be stacked, but the leading edge sags causing improper discharge

Engineering Contradiction:
Improvedistance from discharge rollers to stackerVSAvoidleading edge sagging
Core Design Contradiction:
Length of stationary objectVSShape

Solution Approach 1:

The discharge guide projections are strategically positioned to provide preliminary support to the leading edge of the recording medium as it exits the discharge rollers. This preliminary support prevents the leading edge from sagging during the increased distance travel to the stacker.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The discharge guide projections extend into the discharge path from the roller surface, creating a new dimensional element that intersects the recording medium's path. This three-dimensional arrangement provides support at a critical point in space, preventing sagging without altering the overall roller-to-stacker distance.

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

3Productivity

If the recording medium is discharged over a longer distance, then stacker capacity increases, but page disorder and sheet curl occur

Engineering Contradiction:
Improvestacker capacityVSAvoiddischarge accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The discharge guide projections provide preliminary guidance and support to the recording medium at the point of discharge. This preliminary action ensures proper positioning and prevents page disorder and sheet curl that would otherwise occur during the extended discharge distance to high stack levels.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The discharge guide projections serve as an intermediary mechanism between the discharge rollers and the stacker, maintaining discharge accuracy over longer distances. These projections prevent page disorder and sheet curl by providing continuous guidance throughout the extended discharge path.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2818934B1Medium discharge device and image forming apparatus
Publication Date: 2019.08.07 OKI DATA CORP
  • EP2818934B1 patent drawingFigure 1
  • EP2818934B1 patent drawingFigure 2
  • EP2818934B1 patent drawingFigure 3

AI summary

A medium discharge device includes: a discharge tray having a placing surface on which a medium is to be placed; a first pair of discharge rollers configured to rotate about axes to discharge the medium through a first nip onto the discharge tray; a second pair of discharge rollers configured to rotate about the axes to discharge the medium through a second nip onto the discharge tray; and a discharge guide for guiding the discharged medium. The discharge guide includes a first projection between the first and second pairs of discharge rollers, and a second projection on an opposite side of the first projection with respect to the first pair of discharge rollers. Each of the first and second projections projects to the placing surface side relative to the first and second nips and has a guide surface opposite to the placing surface.