Sheet Positioning Device with Multipoint Contact Detection for Curled Edges

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Solution Overview

Problem

Existing sheet positioning devices in image forming apparatuses fail to accurately align recording sheets when one or both edges are curled, leading to improper detection and subsequent misalignment.

Innovation Solution

A novel sheet positioning device with first and second regulating members and contact detectors that include overhangs and multipoint pressure sensitive members, allowing for detection of sheet edges across the entire loadable range and precise alignment regardless of curling, and a controller to stop the driving mechanism based on detection results.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional sheet positioning devices use simple contact detectors at fixed positions, then the device structure is simple, but the measurement precision of sheet edge position deteriorates when edges are curled

Engineering Contradiction:

Improvesheet edge detection accuracyVSAvoidcontact detector structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The contact detector is divided into multiple detecting points arranged along the sheet loading direction, with each detecting point independently capable of detecting contact with the sheet edge. This segmentation allows the system to detect curled edges at different positions along the sheet length, improving measurement precision without requiring a single complex detector mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The contact detector extends in the sheet loading direction (depth dimension) rather than only across the sheet width. By arranging detecting points along the loading direction, the system can detect edges even when they are curled upward, adding a dimensional capability that resolves the curling problem.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the driving mechanism continues to move side fences to detect contact, then alignment precision improves, but the sheet may warp due to excessive pressure and movement

Engineering Contradiction:

Improvesheet alignment accuracyVSAvoidsheet warping

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The controller receives feedback from multiple contact detectors and uses this information to determine when to stop the driving mechanism. By monitoring contact detection results from multiple points, the system can stop at the appropriate position before excessive movement causes warping, while still achieving sufficient alignment precision.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system uses multiple contact detectors to detect contact at different positions, allowing the driving mechanism to stop at the optimal point rather than continuing to the极限 position. This partial action approach prevents excessive pressure and movement that would cause warping, while still achieving adequate alignment.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If conventional devices use single-point contact detection, then the device complexity is low, but the reliability of detection deteriorates when sheet edges are curled

Engineering Contradiction:

Improvecontact detection reliabilityVSAvoidcontact detector configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The contact detector is segmented into multiple detecting points along the sheet loading direction, where each detecting point independently monitors contact at its specific position. This segmentation improves reliability by ensuring that at least one detecting point will contact the sheet edge even when curled, without requiring a single complex detection mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each detecting point serves multiple functions: detecting contact at its specific position, detecting curling conditions, and providing feedback for stopping the driving mechanism. This multi-functionality improves detection reliability across various sheet conditions without proportionally increasing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8941849B2Sheet positioning device, sheet holding receptacle incorporating same, and image forming apparatus incorporating same

Publication Date: 2015.01.27 RICOH CO LTD

AI summary

A sheet positioning device includes a sheet setting plate, first and second regulating members disposed facing each other to move in an orthogonal direction to a sheet conveyance direction to regulate positions of two facing ends of the sheet on the plate by contacting these ends, a driving mechanism to move the first regulating member in the orthogonal direction, first and second contact detectors mounted on the first and second regulating members to detect contact of the two facing ends, and a controller to stop the driving mechanism based on detection results obtained by the first and second contact detectors. The first and second regulating members are used to adjust a position of the sheet to a predetermined position. Respective contact surfaces of the first and second contact detectors with the sheet extend over an entire maximum loadable range in a sheet setting direction on the plate.