Patent Publication Number: US-6336629-B1

Title: Idler mounting tie-bar assembly

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to sheet transporting devices within an image forming apparatus. 
     2. Description of Related Art 
     Various systems designed for transporting a sheet in a predetermined path have a number of devices to advance the sheet along the predetermined path within an image forming apparatus. Examples of such sheet transporting devices include sheet grippers, drive rolls with idlers and sheet guides. The sheet transporting devices are fixed at various stationary locations along the predetermined path. Consequently, the stationary sheet transporting devices act on the sheet as the sheet is transported through each sheet transporting device. Some systems have multiple sheet transporting devices that move in and out of operative positions, to provide operator access. 
     SUMMARY OF THE INVENTION 
     Conventionally, previous sheet transporting devices for a particular application have been integrated into a single, unitary assembly. 
     One of the advantages of the idler mounting tie-bar assembly is that it locates the drive components of a sheet transporting device in precision frame assemblies that relate to one another through collinear alignment features. The idler mounting tie-bar assembly controls the relationship of the drive roll, the idler roll and the paper guides to minimize variations, which affect paper handling. Additionally the paper guide is able to attach and detach to the precision frame assembly so that the paper guide can be replaced when required. 
     Another advantage of the invention is that the idler mounting tie-bar assembly allows individual components, which tend to wear after use in an image forming apparatus, of the various sheet transporting devices to be replaced independently. Furthermore, the individual components may be separated and removed from the idler mounting tie-bar assembly. 
     Previously, if any one of the sheet transporting devices, such as a sheet guide, the baffle surface, or the like required replacing for any of a variety of reasons, it was necessary to replace the entire assembly, including those sheet transporting devices which were operating adequately. Unfortunately, replacing the entire assembly, if a single paper guide requires replacing, inefficiently discards usable materials and is unnecessarily expensive. Thus, it would be desirable to provide a sheet transporting device assembly that allows individual components of the devices to be independently and detachably mounted or combined together so that individual components of the various sheet transporting devices could be replaced without requiring replacement of the entire assembly. 
     One exemplary embodiment of the tie-bar idler assembly according to this invention is a tie bar idler roller assembly. This invention separately provides a tie bar idler roller assembly that allows the user to access the area in between the idler rollers and drive rollers. 
     The idler tie-bar assembly has a main frame portion having a plurality of grooves, protrusions, openings and bends located within the frame weldment, also referred to as the outer frame as referred to in this application. The idler tie-bar assembly further includes a plurality of openings, each of which is able to receive at least one idler roll. Each of the idler rolls are connected to the idler tie-bar assembly by at least one spring member. The movement of each of the idler rolls is limited in the corresponding opening by a slot located between the two members. The idler roller is able to move vertically along the slot portion. The spring members arc located on each end of a shaft which runs through the middle of the idler roller. The springs pull the idler roll towards the opening on the frame weldment of the idler mounting tie bar assembly with a controlled force. 
     The idler tie-bar assembly also has two end plates located on each end of the frame assembly that aligns the frame to a main support structure. The endplates have locating features. On a pivoting assembly, a pivot device connect the end plates to the main structure. On the opposing end of the end plates, a locking member locks the tie bar idler roller holder assembly in an operative position relative to the main structure. The pivot device allows the tie bar idler roller holder assembly to rotate with respect to the main structure to allow the tie bar idler roller holder assembly into an open position. 
     There are two styles of access assemblies, that usually pivot. The first pivots along the process direction, the second pivots  90  degrees to process direction. Both of these assemblies may use the same alignment principals, to maintain precision location of the components of the apparatus. 
     These and other features and advantages of the systems and methods of this invention are described in or are apparent from the following detailed description of the various exemplary embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This invention will be described in relation to the following drawings, in which reference numerals refer to like elements, and wherein: 
     FIG. 1 is a side view of the tie bar idler roller holder assembly and the outer mainframe in a locked position and pivots in the cross process direction; and 
     FIG. 2 is a perspective view of the tie bar idler holder frame which pivots in the process direction. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows a side-plan view of one exemplary embodiment of a idler mounting tie-bar assembly  100  in an image forming apparatus according to this invention. The idler mounting tie-bar assembly  100  is one exemplary embodiment of a sheet transporting device according to this invention. As shown in FIG. 1, the idler mounting tie-bar assembly  100  comprises a paper guide  112  , also known as a baffle, which is attached to a tie bar idler roller frame  114 , as shown in FIG.  2 . The tie bar idler roller frame  114  has a plurality of grooves, protrusions, and openings. The shape of the tie bar idler roller frame  114  can vary significantly depending on the user&#39;s need and the shape of the paper guide  112  which the idler mounting tie-bar frame  114  is being attached to in an image-forming apparatus. However, a description of just one possible exemplary embodiment for the idler mounting tie-bar frame  114  will be described, as shown in the figures. FIG. 1 shows the tie bar idler assembly  100  being connected to a guide member having a curved shape, whereas FIG. 2 shows the tie bar idler assembly configured in a manner which is more adapted for a guide member having a more planar shape. However, it should be appreciated that the tie bar idler assembly may be configured to correspond to any shape guide member which the user desires. 
     Referring to FIGS. 1 and 2, the idler mounting tie-bar frame  114  has a general rectangular shape with a plurality of openings  115  located on the idler tie-bar frame  114 . Each of the openings  115  is able to receive one or more idler rolls  116 . The idler rolls  116  assist in passing a recording medium (not shown) between paper guides  112  within the image forming apparatus. The idler rolls  116  are generally made from a plastic composite and, in one exemplary embodiment, have a generally cylindrical shape. The idler rolls  116  are able to receive a shaft  118  that is the axis of rotation of the idler rolls  116 , as shown in FIG.  1 . The idler rolls  116  are able to rotate around the shaft in either a clockwise or counterclockwise direction depending on the direction of the drive rolls  126 . The drive rolls  126  are attached to or located in between a guide member  111  which is aligned with guide member  112  during operation of the image forming apparatus. 
     Each end of the shaft  118  is positioned between two members  120  that protrude perpendicularly from the idler tie-bar frame  114 . A slot portion  122  is formed between the two members  120 . The end portions of a shaft  118  are able to be received by a slot portion  122 . Preferably, one pair of two members  120  is located on each side of each opening  115  in the tie bar idler roller frame  114 . The slot portions  122  limit the movement of the shafts  118  to one direction and provide the precise location for aligning the idler rolls  116  and other components. Furthermore, the idler tie bar assembly  100  enables components which are related to one another, such as drive rolls  126 , the idler rolls  116  and the paper guides  111  and  112 , to be more precisely aligned through collinear alignment features. 
     As shown in FIG. 1, the idler rolls  116  and the shafts  118  are attached to the idler tie-bar frame  114  by an attachment member  124 . In various exemplary embodiments, the attachment member  124  is a spring. In specific exemplary embodiments, the attachment member  124  is a torsion spring. However, the attachment member  124  can be a clip, an elastic member, or the like, or any other known or later developed attachment structure. The attachment member  124  provides the necessary normal force to push the idler rolls  116  against the drive rolls  126 . 
     For example, in FIG. 1, the idler rolls  116  and the shafts  118  are attached to the idler tie-bar frame  114  by a plurality of the torsion springs  124 . Each torsion spring  124  runs around or through an opening located on the corresponding shaft II  8  and is removably attached to the idler tie-bar frame  114 . The torsion springs  124  act to pull the idler rollers  116  and the shafts  118  toward the openings  115  located on the idler tie-bar frame  114  and toward the drive rolls  126 . The torsion springs  124  allow the idler rolls  116  to move within the slots portion  122 . Thus, each idler roller  116  can come in contact with a corresponding drive rolls  126 , but at the same time is able to move apart from the drive rolls  126 . In this way, recording medium of different thicknesses and shapes may pass between through the drive rolls  126  and the idler rolls  116 . Generally, each idler roller  116  corresponds to one drive roller  126 . The torsion springs in particular, and the attachment member  124  in general, allow the drive rollers  126  and the idler rollers  116  to reduce the nip force variations which may occur between the drive rolls  126  and the idler rolls  116  as the recording medium pass between them. Furthermore, an elastic member (not shown) may be placed around the shaft  118  to separate the shaft  118  from the two members  120  and the idler tie bar frame  114 . 
     The torsion spring  124  has many functions and advantages which it offers to the tie bar idler roller assembly  100 . First as indicated above, the torsion spring  124  reduces the nip force variation between the idler rolls  116  and the drive rolls  126 . Second, the torsion spring  124  acts as the attachment member to hold the idler rolls  116  to the tie bar idler roller frame  114 . Thirdly, because each torsion spring  124  is attachably connected to the tie bar idler roller frame  114 , the torsion springs  124 , the idler rolls  116  and shafts  118  can easily be detached from the tie bar idler roller holder assembly  100  and be individually replaced, instead of having to replace an entire conventional sheet transporting device assembly when a problem occurs to one of the individual parts of the tie bar idler roller holder assembly  100 . Furthermore, the torsion springs  124 , along with the configuration of the two members  120 , allow the idler rolls  116  and the drive rolls  126  to have their axes of rotation aligned. It should be appreciated that idler rolls  116  could be held in position based on the weight of the idler rolls  116  and the shaft  118 , thus eliminating the need for an attachment member  124 . Furthermore, if the idler rolls  116  and the drive rolls  126  are made of a very soft elastic material this would give a nip force just by interference of the idler rolls  116  and the drive rolls  126 . 
     The tie bar idler roller frame  114  and the guide member  112  are attachably and detachably connected to each other to form the tie bar idler roller holder assembly  100 . The tie bar idler roller frame  114  and the guide member  112  may be connected to each other by a screw, clamps, hooks, or any known or later developed devices able to attachably and detachably connect two components. 
     This is also useful because the tie bar idler roller holder assembly  100  transfers a plurality of recording mediums at high speeds. The inventors have discovered that this tends cause significant wear to the guide member  112 , the idler rollers  116 , the drive rollers  126  and other individual components of the tie bar idler roller holder assembly  100 . Because coated media is very abrasive may cause significant wear on the sheet transporting devices, which therefore requires the components to be replaced at relatively short intervals. Therefore, the individual components of the tie bar idler roller holder assembly  100  may be replaced without having to replace the entire the tie bar idler roller holder assembly  100 , as is required in conventional sheet transporting device assemblies. This allows the cost of replacing worn-out components to be significantly reduced. Therefore, the guide member  112  may be replaced without the need for replacing the idler rollers  116 , the shaft  118  or the other components of the tie bar idler roller holder assembly  100 . 
     End plates  132  are located on each end of the tie bar idler roller holder assembly  100 . The end plates  132  enable the tie bar idler roller holder assembly  100  to be located accurately to an outer main frame  133 . The tie bar idler roller holder assembly  100  is pivotably connected to the outer main frame  133 . Each of the end plates  132  include a pivot slot  130  on one end of the end plate  132 . The pivot slot  130  enables the tie bar idler roller holder assembly  100  to be attached to the outer mainframe  133 . The endplates have alignment feature  147 . The alignment feature  147  is able to connect to the alignment feature (not shown) of the outer main frame  133  so that all corresponding components are properly aligned to reduce the possibility of paper jamming. If the components in sheet transferring devices are not properly aligned, such as idler roll and drive roll or guide members, then this increases the likelihood of the copying media being jammed. Furthermore, if the idlers  116  and  126  are not properly aligned this reduces the gripping capability and may cause the copying media to skew. 
     In the exemplary embodiment shown in FIGS. 1 and 2, a locking member  134  is located on the opposite end of one of the end plates  132  from the pivot slot  130 . The locking member  134  enables the tie bar idler roller holder assembly  100  to be locked into an operative position relative the outer main frame  133 . It should be appreciated that the locking member  134  is positioned so that each time the tie bar idler roller holder assembly  100  is locked to the outer main frame  133 , the idler rolls  116  become aligned with the drive rolls  126  and the idler and drive rolls  116  and  126  are in contact with each other. 
     By having the tie bar idler roller holder assembly  100  pivotably attachable to the outer main frame  133 , the user has greater access to media which becomes jammed between the tie bar idler roller holder assembly  100  and the outer main frame  133 . Once the user unlocks the locking member  134 , the tie bar holder assembly  100  can be swung around its pivot slot  130 , allowing the user access to the region between the idler rollers  116  and the drive rollers  126  and to any individual components which needs to be replaced or accessed. 
     While this invention has been described in conjunction with the exemplary embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention.