Paper Feeder Actuator Design for Curled Sheet Sensing

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Solution Overview

Problem

Existing paper feeders in image forming apparatuses face challenges in accurately sensing curled paper sheets of normal sizes, as the front edge may not come into contact with the actuator, leading to sensing mistakes.

Innovation Solution

A paper feeder design incorporating a first actuator for large sizes and a second actuator for smaller sizes, with the second actuator positioned upstream and featuring inclined sections to ensure contact and sensing of curled paper sheets, even when they are placed on a stacking tray.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the second actuator is disposed within the widths of business cards to sense small size documents, then it can easily sense business cards made of thick paper, but sensing mistakes occur when a front edge of a normal size paper sheet is curled and does not come into contact with either actuator

Engineering Contradiction:

Improvesensing accuracy for small size documentsVSAvoidsensing reliability for curled normal size paper sheets

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The invention changes the spatial arrangement by positioning the second actuator upstream of the first actuator in the paper feed direction, rather than only adjusting width positioning. This dimensional change in actuator placement ensures that curled paper sheets can contact the second actuator first, resolving the sensing mistake problem while maintaining accurate detection of small documents

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If the end on the sensing side of the second actuator is located on a downstream side from the first actuator, then the structure is simplified with a common swing shaft, but the curled paper sheet cannot be sensed properly

Engineering Contradiction:

Improveactuator support structure complexityVSAvoidsensing accuracy for curled paper sheets

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The invention inverts the conventional downstream positioning of the second actuator and places it upstream instead. This inversion allows the second actuator to be the first point of contact for curled paper sheets entering the sensing region, ensuring proper detection while still using the simplified common swing shaft structure

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS9233808B2Paper feeder and image forming apparatus

Publication Date: 2016.01.12 SHARP KK

AI summary

A paper feeder includes a document loading tray 2, a pickup roller 5 and an actuator. The actuator protrudes on a stacking face of the paper sheet stacking tray 2 and senses a paper sheet when touched, pushed and moved by a front edge thereof that is set. The actuator includes a first actuator 21 and a second actuator 22 that are fixed on a common swing shaft. The first actuator 21 is an actuator adapted for paper sheets of first sizes in width direction. The second actuator 22, disposed within business card width at an inner position than the first actuator 21 in width direction, is an actuator adapted for paper sheets of small sizes under normal paper sizes. An end on sensing side 221 of the second actuator 22 is located upstream in paper feed direction from an end on sensing side 211 of the first actuator 21.