Spring-Loaded Pick Arm Assembly for Media Jam Prevention
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Solution Overview
Problem
Automatic document feeders in imaging devices face issues with pick and feed errors due to varying media characteristics and environmental conditions, leading to inconsistent and unreliable media handling, which can result in media jams and damage to scanned documents.
Innovation Solution
A pick mechanism assembly with a movable pick arm and spring system that adjusts the pick roller's normal force and position to accommodate varying media stack heights and conditions, using a rib feature and cantilevered spring to apply dynamic normal forces and hold media stops in place, preventing errant loading and improving media handling consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pick normal force is increased to prevent multi-feeding errors, then media separation reliability is improved, but media jams increase due to excessive force on the media sheet
Solution Approach 1:
The pick mechanism employs a spring-loaded pick arm that dynamically adjusts the pick normal force based on media stack height and conditions. The spring constant and pre-load are calibrated to provide optimal picking force while automatically reducing force when media resistance is encountered, preventing both multi-feeding and media jams
Solution Approach 2:
The system changes the pick normal force parameter dynamically through the spring mechanism, allowing the force to vary with media stack conditions. This enables the pick mechanism to adapt to different media types, weights, and textures without requiring manual adjustment, resolving the contradiction between sufficient picking force and avoiding excessive force
2Manufacturing precision
If a complex mechanism with media stops is used to ensure proper media positioning, then loading accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The pick mechanism itself performs the dual function of picking media and positioning media stops, eliminating the need for separate complex positioning mechanisms. The media stops are integrated into the pick arm assembly and are automatically positioned and retracted by the pick arm's movement, achieving accurate loading without additional complexity
Solution Approach 2:
The invention merges the pick mechanism and media stop positioning function into a single integrated assembly. The pick arm simultaneously performs media selection and media stop placement, reducing the number of components and simplifying the overall mechanism while maintaining loading accuracy
3Reliability
If clutch torque resistance is increased to improve pick force, then pick reliability is improved, but energy consumption and mechanism wear increase
Solution Approach 1:
The invention replaces the clutch-based torque control system with a spring-mechanical system. The spring directly provides the necessary pick force through elastic potential energy, eliminating the need for high-torque clutch engagement and reduction gearing, thereby reducing energy consumption and mechanical wear while maintaining pick reliability
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
The solution effectively reduces pick and feed errors by dynamically adjusting the pick roller's force and position, enhancing media handling reliability and preventing jams, while being cost-effective and simple in design.
Implementation Method 1
A spring is mounted above the pick mechanism to impart a downward force at the first end of the pick arm for holding the pick arm in the raised position
Implementation Method 2
most of which rely upon certain assumptions regarding the general characteristics of friction between the mechanical components of the pick mechanism and the media sheet
Data Source
AI summary
An assembly for restraining media in an input tray includes a pick mechanism having a pick arm mounted at a first end thereof on a shaft. A media stop is positioned to be engageable by a leading edge of the media when the media is disposed in the input tray. The media stop is held by the pick arm in a media stop position for restraining the media in a media loading position when the pick arm is in a raised position and is released by the pick arm from being held in the media stop position when the pick arm is in a lowered position. A spring mounted above the pick mechanism imparts a downward force at the first end of the pick arm for holding the pick arm in the raised position in order to hold the media stop member in the media stop position.