Trailing Edge Guide Detection for Variable Thickness Sheets

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Solution Overview

Problem

Existing sheet feeding devices often incorrectly determine the positional adjustment of the trailing edge guide due to erroneous detection when sheets with varying thicknesses, such as envelopes, are fed, leading to potential double feed or non-feed issues.

Innovation Solution

An image forming apparatus with a movable trailing edge detection portion and a control unit that adjusts the display to prevent warning displays for sheets with thickness differences, ensuring accurate detection and adjustment of the trailing edge guide position, especially for envelopes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a sensor-based trailing-edge rough-setting detection mechanism is implemented, then the positional adjustment of the trailing edge guide can be determined, but erroneous detection occurs when sheets with varying thicknesses (such as envelopes) are fed

Engineering Contradiction:

Improvedetection accuracy of trailing edge guide positionVSAvoidreliability of detection

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The system changes the detection parameter from physical contact detection to optical detection. The optical detection member uses light to detect the presence of the sheet stack, which is not affected by variations in sheet thickness. This resolves the contradiction by maintaining measurement precision while eliminating erroneous detection caused by thickness variations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The mechanical contact-based sensor detection is replaced with an optical detection system. The optical detection member emits light and detects reflections or interruptions to determine the presence and position of the sheet stack, eliminating the mechanical contact issues that arise with envelopes and other sheets of varying thickness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If the trailing edge guide position is strictly monitored with warning displays, then positioning accuracy is enforced, but unnecessary user operations are required when sheets with thickness differences are fed

Engineering Contradiction:

Improvepositioning accuracy of trailing edge guideVSAvoidoperational simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The detection parameter is changed from physical contact to optical detection, allowing the system to accurately detect sheet presence without being affected by thickness variations. This enables the system to maintain positioning accuracy while avoiding false warnings that would require unnecessary user intervention.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If a fixed detection method is used for trailing edge guide positioning, then the detection mechanism is simple, but it cannot adapt to sheets with varying thicknesses

Engineering Contradiction:

Improvedetection mechanism complexityVSAvoidadaptability to different sheet types

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The simple mechanical contact detection is replaced with an optical detection system that is inherently more adaptable. Optical detection can sense the presence and position of various sheet types regardless of their thickness, providing both simplicity and versatility without requiring complex mechanical adjustments.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The optical detection member serves multiple functions: it detects the presence of the sheet stack, determines the trailing edge guide position, and accommodates various sheet types including envelopes. This universal detection method eliminates the need for different detection mechanisms for different sheet types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10114328B2Sheet feeding device and image forming apparatus

Publication Date: 2018.10.30 CANON KK

AI summary

An apparatus includes a movable regulation member that regulates a trailing edge side position of a sheet stack stored in a storage portion in a sheet feeding direction, a trailing edge detection portion, movable together with the regulation member, that detects a sheet surface on the trailing edge side of the sheet stack, and a control unit that detects whether the regulation member is positioned to an end surface on the trailing edge side of the sheet stack based on a detection result by the trailing edge detection portion, and that causes a display unit to provide a warning if the regulation member is not positioned to the end surface, wherein, if a predetermined sheet with thicknesses different between leading edge and trailing edge sides thereof in the sheet feeding direction is set by a setting unit, the control unit does not cause the display unit to provide the warning.