Electric Field Transport Roller for Wet Print Media
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Solution Overview
Problem
Inkjet printing systems face challenges in transporting print media during drying, as nip rollers can damage wet images and vacuum transport belts cause uneven heating, leading to issues like density and gloss shifts, especially with coated papers which have lower porosity, requiring a mechanism that facilitates drying while minimizing these problems.
Innovation Solution
The implementation of electric field-generating transport members with drive rollers featuring spaced electrical conductors and a commutator that applies voltage to only a subset of conductors in proximity with the print media, creating a frictional force to convey sheets without contacting the upper surface, thus avoiding the need for nip rollers and ensuring even drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If nip rollers are used to transport print media, then the sheet can be conveyed through the printer, but the wet image can be damaged through contact
Solution Approach 1:
The patent replaces mechanical contact-based transport (nip rollers) with an electrostatic field-based transport system. The electrostatic transport member generates an electric field that interacts with the conductive ink on the sheet, providing contactless transport and eliminating mechanical damage to the wet image while maintaining effective sheet conveyance through the printer
2Ease of operation
If vacuum transport belts are used to convey sheets, then the sheet can be transported, but uneven heating of the sheet occurs
Solution Approach 1:
The patent replaces vacuum belt transport with electrostatic field-based transport, eliminating the physical contact and suction mechanism that causes uneven heating. The electrostatic transport member provides contactless conveyance, allowing uniform heat distribution across the sheet during the drying process and preventing density and gloss shifts
3Ease of operation
If vacuum transport is used, then the sheet can be held and conveyed, but the air flows in the dryer must be reduced due to limited acquisition and holding latitude
Solution Approach 1:
The patent replaces vacuum-based sheet holding with electrostatic field-based holding. The electrostatic transport member generates sufficient electrostatic force to acquire and hold the sheet with greater latitude, enabling the dryer to operate at higher air flow rates and maintain optimal drying efficiency without compromising sheet transport control
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
This solution allows for the transportation of wet sheets without damaging the image, achieves more even drying, and enables lower dryer temperatures by using electrostatic forces to maintain sheet tension, reducing the risk of roll contamination and image distortion.
Implementation Method 1
Each of the at least one transport member includes a drive roller which is rotated about an axis of rotation to advance the print media in the downstream direction. The drive roller includes spaced electrical conductors. First portions of the electrical conductors are sequentially brought into proximity with the print media as the roller is rotated.
Implementation Method 2
creating a frictional force to convey sheets without contacting the upper surface
Data Source
AI summary
A printer includes a printhead assembly which applies an ink composition to print media to form printed media. A dryer, downstream of the printhead assembly, at least partially dries the printed media. A transport mechanism conveys the printed media in a downstream direction between the printhead assembly and a dryer and between the dryer and an output device. The transport mechanism includes at least one electric field-generating transport member including a drive roller which is rotated about an axis of rotation to advance the print media in the downstream direction. The drive roller includes spaced electrical conductors, first portions of the electrical conductors being sequentially brought into proximity with the print media as the roller is rotated. A commutator is positioned to sequentially contact and apply a voltage to second portions of only a subset of the conductors that are in proximity with the print media.