Sheet Stacker Leading End Guide and Air Exhaust for High-Speed Stacking

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Solution Overview

Problem

Existing image forming apparatuses face challenges in efficiently stacking sheets without conveyance failures, such as collisions, gaps, or creases, especially when increasing the conveyance speed of sheets.

Innovation Solution

The improved sheet stacker incorporates a leading end guide that holds and releases the sheet's leading end, combined with an air exhaust that removes residual air above the sheet stack, facilitating smooth sheet stacking and reducing air resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the conveyance speed of sheets is increased to improve productivity, then the throughput of the image forming apparatus is improved, but sheet collisions, gaps, or creases occur due to air resistance and improper stacking

Engineering Contradiction:

ImprovethroughputVSAvoidstacking quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A leading end guide is introduced as an intermediary component between the conveyor and the stacker. The guide holds the leading end of the sheet during conveyance and releases it at the appropriate timing, mediating the interaction between the high-speed conveyor and the stacking mechanism to prevent collisions and maintain stacking quality at increased speeds

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The leading end guide performs preliminary actions by holding the sheet's leading end before stacking occurs. This preliminary holding action ensures proper positioning and timing, preventing collisions and gaps during the stacking process while enabling higher conveyance speeds

Inventive Principle:

Principle #10Preliminary action

2Loss of time

If the conveyance speed is increased to reduce processing time, then the efficiency is improved, but air resistance causes conveyance failures such as collisions or creases

Engineering Contradiction:

Improveprocessing timeVSAvoidair resistance

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The leading end guide acts as a mediator that shields the sheet from harmful air resistance effects. By holding and guiding the sheet's leading end, it reduces the impact of air resistance that would otherwise cause collisions, gaps, or creases at high conveyance speeds

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces pure mechanical conveyance with a combined mechanical-pneumatic system. An air exhaust device is introduced to actively manage air resistance by exhausting air from the stacking area, supplementing the mechanical guiding action and enabling stable high-speed operation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If sheets are stacked without air exhaust, then the device complexity is reduced, but residual air causes conveyance failures and stacking quality degradation

Engineering Contradiction:

Improvestacker structureVSAvoidconveyance reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

A pneumatic system (air exhaust device) is introduced to manage air resistance in the stacking area. The air exhaust device actively removes residual air that would otherwise cause conveyance failures, improving reliability without significantly increasing overall system complexity

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent changes the environmental parameter (air pressure/residual air) in the stacking area by introducing an air exhaust device. This parameter change reduces air resistance effects and improves conveyance reliability, enabling stable operation at higher speeds

Inventive Principle:

Principle #35Parameter changes

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 solution enhances the throughput of the image forming apparatus by preventing sheet collisions and ensuring proper stacking, even at increased conveyance speeds, while maintaining the quality of the sheet stacking process.

Implementation Method 1

an air exhaust to exhaust the residual air above the stack of sheets to an upstream from the tray in the conveyance direction

Methodology Applied

Scientific EffectAir exhaust:

Data Source

PatentUS12208981B2Sheet stacker and image forming apparatus incorporating same

Publication Date: 2025.01.28 RICOH CO LTD

AI summary

A sheet stacker includes a tray to store a stack of sheets, a conveyor above the tray, a leading end guide above the tray, and an air exhaust. The conveyor conveys a sheet in a conveyance direction. The leading end guide is downstream from the conveyor in the conveyance direction. The leading end guide guides the sheet from the conveyor to the tray. The air exhaust exhausts air above an upper surface of the stack of sheets on the tray to an upstream from the tray in the conveyance direction. Further, the leading end guide holds a leading end of the sheet conveyed by the conveyor at a holding position and releases the leading end of the sheet at a release position downstream from the holding position in the conveyance direction.