Patent Grant
7717417
The present application is directed to methods and devices for moving media sheets in an image forming device and, more specifically, to methods and devices for preventing and/or reducing transverse buckling of media sheets within the image forming device.
An image forming device, such as a color laser printer, facsimile machine, copier, all-in-one device, etc, includes a media feed system for introducing and using media sheets. The media feed system includes an input area where media sheets are initially placed prior to being introduced into a media path. A pick mechanism may also be located in the input area to contact and move a media sheet from the input area and into the media path. The proper functioning of the device requires that media sheets are fed reliably and consistently, as well as maintaining the proper timing between media sheets.
New image forming devices are trending towards lower cost, smaller height/footprint, and higher print quality. The smaller sizes have various advantages including that the devices fit within a smaller workspace and a reduction in shipping and packaging costs. In order to conserve space, a primary input tray and a multipurpose feeder may be located in the same general horizontal plane.
The present application is directed to devices and methods for moving media sheets in an image forming device. In one embodiment, a contact member includes a contact roller that contacts a top-most media sheet in a stack of media sheets positioned on a support surface in an input area of the image forming device. A hub extends outward from an axial side of the contact roller. The hub includes a smaller diameter than the contact roller, forming a gap between the hub and the top-most media sheet when the contact roller is in contact with the top-most media sheet. The hub prevents or reduces transverse buckling of the top-most media sheet when it is moved from the stack of media sheets.
The contact member 15 includes a contact roller 14 that contacts a top-most media sheet in a stack of media sheets 12. The stack of media sheets 12 is positioned on a support surface 101 in an input area 102 of the image forming device 100 (
To understand the context of the present application,
Media sheets 12 are moved from the input area 102 and fed into a primary media path 104. One or more registration rollers 105 align the media sheets 12 and precisely control its further movement along the media path 104, A media transport belt 106S forms a section of the media path 104 for moving the media sheets 12 past a plurality of image forming units 107. Color printers typically include four image forming units 107 for printing with cyan, magenta, yellow, and black toner to produce a four-color image on the media sheet 12.
An imaging device 108 forms an electrical charge on a photoconductive member within the image forming units 107 as part of the image formation process. The media sheet 12 with loose toner is then moved through a fuser 109 that adheres the toner to the media sheet 12. An exit roll 10 forming a nip with a nip roll 110 is positioned at an output area. The exit roll 10 is driven by a motor 120 and rotates in a forward direction to expel the media sheet 12 from the device 100 and out to an output tray 112. Alternatively, the exit roll 10 may rotate in a forward direction for a limited time until a trailing edge of the media sheet 12 passes an intersection point 113 along the media path 104. The exit roll 10 is then rotated in a reverse direction to drive the media sheet 12 into a duplex path 114. The duplex path 114 directs the inverted media sheet 12 back through the image formation process for forming an image on a second side of the media sheet 12.
Examining the input area 102 now in more detail,
The input mechanism 90 includes a pick arm 20 pivotally positioned or a shaft 24. A drive shaft 16 extends outward from a distal end of the pick arm 20. In one embodiment as illustrated in
One or more contact rollers 14 are attached to the drive shaft 16. In the embodiment of
A cantilevered hub 17 has one end connected to an axial side of contact roller 14 and has a free end extending outwardly from the axial side of the contact roller 14. Hub 17 extends outwardly from the contact roller 14 in a direction away from the pick arm 20 (see
A schematic end view of the contact roller 14 and hub 17 is shown in
The cross-sectional shape of the hub 17 may vary.
As stated previously, the media sheets 12 are moved from the media stack to the media path 104. The contact roller 14 is rotated and initiates movement of the top-most media sheet 12. The contact roller 14 may form a normal buckle in the media sheet 12 that prevents more than one media sheet from being simultaneously moved from the media stack. The normal buckle is substantially perpendicular to the direction of feed. A leading edge of the media sheet 12 makes contact with the dam 30 such that the movement of the media sheet 12 changes from a substantially horizontal plane (i.e., essentially parallel to the support surface 101) to a plane at a vertical angle with the horizontal plane. The normal buckle in the media sheet 12 ideally forms a smooth bend in order to make this transition. During this movement, a transverse buckle may be formed in the media sheet 12. The transverse buckle is substantially parallel to the direction of feed. The transverse buckle increases a beam strength of the media sheet 12 causing it to resist the creation of the normal buckle. The media sheet with the transverse buckle is more difficult to feed and may result in media jams and improper timing of the media sheet.
Transverse buckling is most prevalent in a media sheet with multiple layers, such as an envelope. Envelopes generally include multiple layers formed by front and back sides, and a flap that closes the envelope. As the envelope is moved from the support surface 101, the contact roller 14 contacts a single layer. This may cause the other envelope layers that are not contacted to move from the support surface 101 at a different speed. This speed differential causes formation of the transverse buckle.
As the media sheet 12 begins to form a transverse buckle, the transverse buckle makes contact with the hub 17. This contact operates to arrest further development of the transverse buckle and prevents the transverse buckle from exceeding a size of the gap 19. The transverse buckle, then, is not allowed to reach the critical limit where a crimp forms thus allowing it to be fed more reliably. In one embodiment, the hub 17 rotates along with the contact roller 14. In another embodiment, the hub 17 does not rotate.
In one embodiment, the hub 17 is constructed of a material with a coefficient of friction substantially lower than the coefficient of friction of the con-tact roller 14. The lower coefficient of function may allow the hub 17 to contact the media sheet 12 without imparting a driving force. Thus, when the transverse buckle makes contact with the hub 17, the hub 17 does not apply a significant additional driving force to the media sheet 12 as compared to the contact roller 14. This reduces the possibility of skewing the media sheet 12 as a result of contact with the hub 17. The contact roller 14 may be constructed from a variety of materials including but not limited to isoprene rubber and cork. The hub 17 may be constructed from a variety of materials including but not limited to thermoplastics such as acrylonitrile butadiene styrene, plastics and metals.
In one embodiment, the smaller the gap 19 the more efficiently the hub 17 breaks down the transverse buckle into smaller creases. However, the size of the gap 19 may be adjusted to account for particular characteristics of the media sheet 12 being fed. For example, a smaller gap 19 may be used with thinner and more flexible media sheets 12. Such media sheets 12 may more easily form smaller creases that fit within the gap. Thicker and stiffer media sheets 12 may require a larger gap because transverse buckles in such media sheets 12 may not easily break down into smaller creases without permanently distorting the media or result in a misfeed.
In one embodiment, the hub 17 is removable from the contact roller 14. Hubs 17 with different widths and lengths may be attached to the contact roller 14 to accommodate feeding of the particular media sheets 12. For example, a hub 17 with a length only slightly smaller length than the contact roller 14 may be used when feeding sheets of 20 pound bond paper. However, a hub 17 with a greater difference in length than the contact roller 14 may be required to reliably feed envelopes constructed from 40 pound Bristol paper. In another embodiments the width W2 of the hub 17 may also be varied to accommodate media sheets 12 of different overall dimensions.
The embodiment illustrated in
The embodiment illustrated in
The embodiment of
The present assembly is applicable to preventing and/or reducing transverse buckling in media sheets with multiple layers, such as envelopes. The assembly may also be used with other multiple layer media sheets such as carbon-copy materials. Additionally, the assembly may also be used to prevent and/or reduce transverse buckling in various other types of media sheets such as but not limited to paper, transparencies, and card stock.
Terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc and are also not intended to be limiting. Like terms refer to like elements throughout the description.
As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.
The present application may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of these embodiments. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
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