Pick Mechanism Height Adjustment for Media Feeding Reliability
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Solution Overview
Problem
Existing media feed systems for image forming devices have difficulty accommodating various types of media due to a fixed pick height, leading to issues such as misfeeds and failures when handling media with different densities, weights, and stiffnesses.
Innovation Solution
A media feeding system with a pick mechanism that adjusts its height based on media type using a flag with light blocking and passing regions and an optical sensor, controlled by a lift mechanism and controller to determine the correct pick height for different media types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed pick height is used for all media types, then the device structure is simple, but feeding reliability deteriorates when handling media with different densities, weights, and stiffnesses
Solution Approach 1:
The pick height is made dynamically adjustable based on media type. The lift plate can be positioned at multiple heights (first, second, and third positions) corresponding to different media characteristics. The controller automatically selects the appropriate height based on detected media type, transforming a static system into a dynamic one that adapts to varying requirements.
Solution Approach 2:
The pick height parameter is changed according to media type. The system provides at least three distinct pick height positions to accommodate different media properties such as density, weight, and stiffness. This parameter adjustment ensures optimal feeding reliability for each media type without requiring complex continuous adjustment mechanisms.
2Reliability
If a single pick height is used, then the mechanism is simple, but media compression and misfeeds occur for compressible media like envelopes or labels
Solution Approach 1:
The lift plate position is dynamically adjusted based on media compressibility. For compressible media, the system selects appropriate heights that prevent excessive compression and subsequent misfeeds, transforming the static single-height system into a dynamic multi-height system.
Solution Approach 2:
The system performs preliminary detection of media type and pre-positions the lift plate at the appropriate height before feeding begins. This preliminary action prevents compression-related issues by establishing the correct pick height in advance, rather than attempting to correct problems during the feeding process.
3Reliability
If the pick mechanism contacts media at a fixed angle, then the separator force is consistent, but heavier media push out the media tray due to excessive separator force
Solution Approach 1:
The pick height parameter is adjusted to change the contact angle between the pick mechanism and media. For heavier media, a different height position is selected that results in a more favorable contact angle, reducing the separator force component that pushes media against the tray and preventing tray ejection.
Solution Approach 2:
Different pick height positions provide locally optimized contact conditions for different media types. Each height position is designed to create appropriate mechanical conditions (angle and force distribution) for specific media characteristics, ensuring tray stability for heavy media while maintaining effective feeding for lighter media.
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
Enables reliable feeding of various media types by adjusting the pick height, reducing misfeeds and failures by ensuring the appropriate normal force is applied, regardless of media density, weight, or stiffness.
Implementation Method 1
An optical sensor includes an emitter and a photo-receiver spaced to allow the flag to pass therebetween and provides an output signal that changes between a first state and a second state as the light blocking and light passing regions of the flag pass between the emitter and the photo-receiver
Data Source
AI summary
A method for adjusting a pick height of a pick mechanism includes determining a media type for a media stack. When the media type is a first media type, the lift plate is raised to raise the media stack and pick mechanism until a first light blocking region of a flag extending from the pick mechanism blocks an optical path of a sensor indicating that the pick mechanism has reached a first pick height. When the media type is a second media type, the lift plate is raised to raise the media stack and pick mechanism such that the first light blocking region first blocks the optical path, a first light passing region of the flag subsequently unblocks the optical path, and then a second light blocking region of the flag subsequently blocks the optical path indicating that the pick mechanism has reached a second pick height.