Patent Application
20120013692
In a printer or other type of paper handler, the paper or medium may move through the printer along a media path using a combination of belts and rollers.
Various arrangements of belts and rollers may wrinkle or otherwise damage the paper. In other instances, the belts and rollers may contact freshly-printed surfaces and damage the printed image.
Where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. Moreover, some of the blocks depicted in the drawings may be combined into a single function.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the invention. However, it will be understood by those of ordinary skill in the art that the embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the present invention.
Embodiments of the present invention may be used in a variety of applications. Although the present invention is not limited in this respect, the techniques disclosed herein may be used in paper handling machines such as inkjet and laser printers, photo printers, multi-function printers, copiers, presses, and the like.
Printed images or impressions on a freshly-printed surface on a medium (such as paper or cards) may be damaged by rollers used to advance or guide the medium through the printer. Embodiments of the invention may provide an apparatus and techniques that minimize such damage. Such embodiments may include a roller assembly having a set of conical rollers that are tapered such that the paper may be contacted just at the edges.
Reference is now made to
The parts and blocks shown in
A conceptual illustration of drying area 60 is shown in
Reference is now made to
Roller assembly 70 can guide medium 5 in two typical types of printer arrangements—edge-justified and center-justified. Justification refers to the position of the medium relative to the printer's media path as the medium travels through the printer. Edge-justified refers to a medium traveling though the printer contacting a guide on one edge. Center-justified refers to a medium that travels through the printer centered between the edges of the printer. In center-justified printers, roller assembly 70 can help to self-center medium 5 while it travels through printer 100.
Typically, the image on the medium as it exits printing area 40 may still be wet. Thus, even though conical rollers 72 nominally contact medium 5 at the edges, it is advantageous to use non-stick roller material, at least on the outer surface of the roller. Several Teflon®-based materials are good for this: Teflon® itself (polytetrafluoroethylene or “PTFE”), Teflon-FEP, sometimes called simply “FEP” (for fluorinated ethylene propylene), and Teflon-PFA, sometimes called simply “PFA” (for perfluoroalkoxy). Teflon-FEP and PFA are also easy to injection mold into rollers. Delrin® (polyoxymethylene, also known as “POM,” polyacetal, or polyformaldehyde), made by DuPont, is less expensive than Teflon®-based materials, is relatively non-stick, and can be injection molded into rollers. These materials are listed in descending order of non-stickiness.
Reference is now made to
Reference is now made to
If belt 65 is included in printer 100, one consideration in using it is the tension of the belt, which may typically be 15 to 20 Newtons. A low tension allows the medium to wander either left or right without excessive pinching or binding of the medium, which may result in damage to the freshly-printed surface. As the medium moves to the right side of the printer (see arrow 78), it may tend to get pushed further into the flat belt due to the conical roller. Because the belt may be set to a very low tension, it is sufficiently compliant such that the belt can move out of the way (see arrows 68) and minimize detrimental effects to the photo surface due to what could otherwise be excessive pinch force. The opposite effect may be true if the medium tends to move to the left side of the printer. A printer having flat rollers rather than conical rollers may not be capable of operating in this fashion.
If belt 65 is included in printer 100, another consideration may be where to place roller assembly 70 in relation to belt 65. If roller assembly 70 is located near rollers 62 or 64, there may too much resistance and not enough compliance. Locating the roller assembly toward the middle of the belt allows the roller assembly to move up and down more easily. Typical placement of roller assembly 70 in terms of belt length L may be one-quarter or one-third L (also called one-quarter or one-third span), or even one-half L (roller assembly 70 would be in the middle of the belt).
In sum, a roller assembly for use in printer is described that may be used to guide a freshly-printed medium through a printer without damaging the printed image. This may be accomplished by using conical rollers, which may be made of a non-stick material, that contact the medium only by the edges. The conical roller assembly may also self-center the medium as it travels through the printer, and is able to accommodate a range of media weights and widths.
The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.
