Patent Application
20080106028
Image forming devices move media sheets along a media path. The media sheets initially begin at an input area that is sized to hold a stack of sheets. Each sheet is individually picked from the stack and introduced into the media path. The media path comprises a series of roller nips guides and/or belts. The sheets move along the media path and through an imaging area where an image is transferred to the sheet. The media sheet is then either output from the device, or recirculated through a duplex path for receiving an image on a second side.
Media sheets should be moved from the input area and into the media path in a timely manner. The distance between sheets moving along the media path is preferably minimized to increase the overall throughput of the device. The device throughput is the number of media sheets that receive a toner image and are outputted from the device within a given time period. Higher throughput devices are usually preferred by users.
A pick mechanism is positioned at the input area for moving the media sheets into the media path. The pick mechanism includes a pick tire that contacts the media sheet. Rotation of the pick tire moves the media sheet from the input area into the media path. The surface of the pick tire should have an adequate coefficient of friction with the media sheet such that rotation of the tire moves the media sheet into the media path. The pick tire should not slip during rotation because this could cause the media sheet to be delayed in moving into the media path that could result in a print defect or a media feed failure. Further, the pick tire should be constructed to be durable to withstand feeding a large number of media sheets into the media path prior to demonstrating wear.
The present application is directed to pick tires for moving media sheets along a media path in an image forming device. The pick tire may include a base that includes an inner surface and an outer surface. The outer surface includes a plurality of teeth that contact the media sheets. The plurality of teeth may be integrally molded with the base. The molded construction may be consistently duplicated during the manufacturing process and may be a substantial cost savings over prior non-molded designs.
The present application is directed to a pick tire for moving media sheets along a media path in an image forming device. The pick tire includes a base with teeth on an outer surface that contact the media sheets. The teeth are integrally molded into the tire. The molded construction reduces manufacturing costs, provides manufacturing consistency, and increases durability.
The input area 113 is disposed in a lower portion of the main body 112, and is preferably removable for refilling. Pick mechanism 116 picks the top-most sheet from the stack 114 and moves the sheet into the media path 120. The term “pick” refers to moving the media sheet from the media stack 114 into the media path 120. Registration nip 121 formed between rolls 122 align the media sheet prior to passing to a transport belt 123 and past a series of image forming stations 103. A print system 142 forms a latent image on a photoconductive member in each image forming station 103 to form a toner image. The toner image is then transferred from the image forming station 103 to the passing media sheet.
Color image forming devices typically include four image forming stations 103 for printing with cyan, magenta, yellow, and black toner to produce a four-color image on the media sheet. The transport belt 123 conveys the media sheet with the color image thereon towards a fuser 124, which fixes the color image on the media sheet. Exit rollers 126 either eject the print media to an output tray 128, or direct it into a duplex path 129 for printing on a second side of the media sheet. In the latter case, the exit rollers 26 partially eject the print media and then reverse direction to invert the media sheet and direct it into the duplex path 129. A series of rollers in the duplex path 129 return the inverted print media to the primary media path for printing on the second side
Historically, the teeth 10 on the outer surface 12 of the pick tires 10 were formed by a grinding process. However, grinding the teeth 20 on the outer surface 12 resulted in numerous disadvantages. A first disadvantage was the inconsistencies in the teeth 20 and the outer surface 12. Each production run from a manufacturer often resulted in pick tires 10 with different physical characteristics. More problematic was the inconsistency in pick tires 10 when using multiple different manufacturers. Another disadvantage with grinding teeth 20 was the cost of the grinding process often constituted up to half of the total cost of manufacturing the pick tire 10. A third disadvantage was the difficultly in orienting and servicing the pick tire 10 due to the small size of the teeth 20. The small size made it difficult for visual inspection and often resulted in the pick tire being mounted to the pivoting arm 117 with the teeth 20 aligned in the wrong orientation.
The pick tire 10 of the present application includes teeth 20 that are integrally molded with the base 19. This construction eliminates the grinding process required by prior pick tires. The molded pick tires 10 are less costly to manufacture with savings of up to one-half the overall cost of the pick tire 10. Molding further increases quality and consistency because the dimensions of the pick tire 10 are controlled by a mold instead of a separate, individualized grinding process. Further, the molded pick tires 10 are easier to assemble and service because the orientation is easier to determine or is inconsequential. In one embodiment, an insignia 13 is molded into the side of the base 19 to indicate the orientation of the teeth 20.
Teeth 20 may be aligned in a lateral orientation as illustrated in
The outer surface 12 may further be textured to provide an increased grip on the media sheets. The texture may be on a limited section of the outer surface 12, or across substantially the entirety of the outer surface 12. In one embodiment, the teeth 20 are textured. In another embodiment, the gaps 24 are textured.
The teeth 20 may extend outward at a variety of angles from the outer surface 12.
The tip 23 of each tooth 20 may include a variety of shapes.
In one embodiment, the pick tire 10 including the base and teeth 20 are formed by compression molding. The molding material is initially placed in a mold cavity. The mold cavity and/or the molding material may be preheated prior to placement of the material within in the cavity. After the material is inserted, the cavity is closed and pressure is applied to force the material throughout the mold. The pressure ensures that the material completely fills the teeth. Pressure and heat may be applied to the mold cavity during the molding process until the molding material is cured. After curing, the pick tire 10 is removed from the mold. The pick tire 10 with the molded teeth 20 may be substantially similar to the previous pick tires that require a secondary grinding operation.
The pick tire 10 may be constructed from various materials including a rubber composition that includes isoprene rubber, at least one ozone-resistant rubber such as EPDM, and a rubber curing system substantially soluble in the mixture of the isoprene rubber and ozone-resistant rubber. The rubber composition may also include an effective amount of a mild antioxidant such as hindered phenols, hindered bisphenols, hydroquinolines, and mixtures thereof. Various compositions are disclosed in U.S. Pat. No. 5,932,313 herein incorporated by reference.
The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. 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
