Sheet Alignment Mechanism with Dual Home Position Detection

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Solution Overview

Problem

Existing sheet alignment mechanisms in image forming apparatuses face issues with alignment accuracy due to lack of detection for malfunction in drive systems and dimensional fluctuations, leading to misalignment or sticking of sheets.

Innovation Solution

A sheet alignment mechanism with a pair of movable side fences, a single drive source, and dedicated detecting units for each side fence's home position, allowing for precise alignment and real-time detection of positional deviations to prevent malfunctions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single sensor is used to detect the home position of side fences, then the structure is cost effective, but malfunction in the drive system or assembly deviation cannot be detected

Engineering Contradiction:
Improvecost effectivenessVSAvoiddetection reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent divides the detection function into two separate sensors, each responsible for detecting the home position of one side fence. This segmentation allows independent monitoring of each side fence's position, enabling detection of malfunctions or assembly deviations that would be impossible with a single sensor.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If side fences are moved symmetrically by a single drive source, then the structure is simplified, but dimensional errors and installation shifts cause gap variations leading to misalignment

Engineering Contradiction:
Improvedrive system complexityVSAvoidalignment precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent introduces feedback mechanisms where two sensors detect the actual positions of both side fences, and a control unit processes this information to calculate dimensional errors and installation shifts. The system then adjusts the drive commands to compensate for these errors, maintaining alignment precision despite using a simplified single drive source.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP1886830B1Sheet Alignment Mechanism, Sheet Post-Processing Apparatus, and Image Forming Apparatus
Publication Date: 2016.11.23 RICOH CO LTD
  • EP1886830B1 patent drawingFigure 1
  • EP1886830B1 patent drawingFigure 2
  • EP1886830B1 patent drawingFigure 3

AI summary

A sheet alignment mechanism includes a stacking tray (50) on which a sheet or sheet bundle transported along a sheet transport path is stacked, a pair of side fences (53) that are movable in a sheet width direction and align edges of the sheet or sheet bundle, stacked on the stacking tray (50), in the sheet width direction, a single drive source (158) that moves the side fences (53), and detecting unit (314a, 314b)s that detect home positions of the respective side fences (53).