Apparatus for varying pressure roll nip force

Abstract

An apparatus for varying nip pressure in a media feedpath including a feed roller and a pressure roller defining a feed nip there between includes a rotatable cam having a preselected eccentric path when rotated, a first pivotable linkage pivotally engaging the rotatable cam, a second pivotable linkage, a biasing member operably interconnecting the first and second pivotal linkages for providing a biasing force on the pressure roller. The pressure roller is rotatably connected to the second linkage opposite the biasing member, wherein rotation of the cam varies the biasing force provided by the biasing member on the pressure roller.

Description

CROSS REFERENCES TO RELATED APPLICATIONS [0001] None. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] None. REFERENCE TO SEQUENTIAL LISTING, ETC. [0003] None. BACKGROUND [0004] 1. Field of the Invention [0005] The present invention relates generally to media feed mechanisms, and more particularly to a media feed mechanisms in printing and / or scanning mechanisms. [0006] 2. Description of the Related Art [0007] All-in-one machines typically perform functions such as printing, scanning, copying, and faxing in either a stand alone fashion or in conjunction with a personal computer and define a growing market for peripheral devices. These devices eliminate clutter in a business or home office by combining the desirable functionality of various machines into a single unit, while maintaining an affordable cost. Various all-in-one machines currently in the marketplace use thermal inkjet technology as a means for printing received fax documents, original documents, and...

AI Technical Summary

Benefits of technology

[0014] The present invention inhibits media jump when media exits the nip between the pressure roll and the feed roll.

[0018] According to a fourth embodiment, a variable force pressure roll linkage comprises a media feedpath, a drive roller located along the media feedpath, a biasable idler roller rotatably disposed opposite and biased toward the drive roller and forming a nip therebetween for feeding media, and, a variable force means which decreases biasing force on the idler roller during media exit from the nip.

[0020] The present invention allows for varying of force on a pressure roller when a media trailing edge passes a feed nip thereby inhibiting media jump and printing and scanning degradation.

Problems solved by technology

The media may advance some undesirable distance corresponding to the backlash of a gear train driving the feed roller.

The problem worsens when thicker media is utilized.

Due to the over-advancement of the media, the printhead is moved from its intended position relative to the medium resulting in ink droplets being deposited inconsistently and reduced print quality.

For example, banding may occur which is undesirable.

In the case of ADF scanning, the media jump can result in scanning quality defects.

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