Cleaner units and methods for removing waste toner within an image forming device

The present application is directed to cleaner units and methods for removing waste toner from a transfer member within an image forming device. The device may include a blade that is positioned against the transfer member to remove the waste toner. The blade directs the waste toner into a cleaner house where the waste toner is removed. The cleaner unit is positioned within the image forming device to prevent contact with the media sheets moving along the media path. The cleaner unit may also be positioned to utilize existing elements to facilitate the removal of the waste toner from the transfer member.

BACKGROUND

The present application is directed to image forming devices and, more particularly, to devices and methods for removing waste toner from a transfer member within an image forming device.

Image forming devices, such as color laser printers, produce images on print media that pass along a media path. The images are formed by one or more toner images that are formed on a transfer member and then transferred to the media sheets. During transfer of the toner images to the media sheets, some of the toner is not transferred and remains on the transfer member. This non-transferred toner, or waste toner, should be removed from the transfer member. Waste toner that remains on the transfer member may be inadvertently transferred to a subsequent media sheet resulting in a print defect.

A cleaner unit should remove the waste toner to an extent to prevent or greatly reduce the likelihood of print defects. Preferably, the cleaner unit should be constructed to not greatly increase the overall cost of the device. The current market for image forming devices is extremely competitive and price points may drive a purchasing decision for consumers. It is preferable that the device be able to produce high quality images and still be competitively priced.

The transfer member may move around a series of rollers as it receives the toner images and transfers them to the media sheets. The cleaner unit may be positioned opposite from one of the rollers to provide good contact with the transfer member. Prior art devices have positioned the cleaner unit in a manner for gravity to assist in the removal of the waste toner from the transfer member.

SUMMARY

The present application is directed to cleaner units and methods for removing waste toner from a transfer member within an image forming device. In one embodiment, the device may include a blade that is positioned against the transfer member to remove the waste toner. The blade directs the waste toner into a cleaner house where it can be removed. The cleaner unit is positioned within the image forming device to prevent contact with the media sheets moving along the media path. The cleaner unit may also be positioned to utilize existing elements to facilitate the removal of the waste toner from the transfer member.

DETAILED DESCRIPTION

The present application is directed to devices and methods for removing waste toner from a transfer member within an image forming device. The devices and methods remove the waste toner to prevent the waste toner from inadvertently being placed on a media sheet and causing a print defect.

In one embodiment, the image forming device comprises a color laser printer. The printer may be sized to fit on a workspace, such as a desktop. A user may use the printer to produce monochrome and/or color images. The printer further includes accessible work areas to allow the user to insert and remove media sheets, and clear media jams from the interior of the printer.

FIG. 1illustrates one embodiment of an image forming device, generally illustrated as10. The device10includes a media input tray68positioned in a tower section of a body12. The tray68is sized to contain a stack of media sheets that will receive color and/or monochrome images. The media input tray68is preferably removable for refilling. Therefore, in this embodiment, a user may insert and remove the media input tray68from the device10through a front13of the body12. A control panel14may be located on the front13of the body12. Using the control panel14, the user is able to enter commands and generally control the operation of the image-forming device10. For example, the user may enter commands to switch modes (e.g., color mode, monochrome mode), view the number of images printed, take the device10on/off line to perform periodic maintenance, and the like.

A first toner transfer area30includes one or more imaging units31that are aligned horizontally extending from the front13to a back15of the body12. Each imaging unit31includes a charging roll32, a developer roll33, and a rotating photoconductive (PC) drum34. The charging roll32forms a nip with the PC drum34, and charges the surface of the PC drum34to a specified voltage such as −1000 volts, for example. A laser beam35from a printhead36contacts the surface of the PC drum34and discharges those areas it contacts to form a latent image. In one embodiment, areas on the PC drum34illuminated by the laser beam35are discharged to approximately −300 volts. The developer roll33, which also forms a nip with the PC drum34, then transfers toner particles from a toner reservoir37to the PC drum34to form a toner image. The toner particles are attracted to the areas of the PC drum34surface discharged by the laser beam35.

A toner reservoir37is operatively connected to each of the imaging units31. The toner reservoirs37are sized to contain toner that is transferred to the imaging units31for image formation. The toner reservoirs37may be mounted and removed from the device10independently from the imaging units31. In one embodiment, the toner reservoirs37each contain one of black, magenta, cyan, or yellow toner. Each of toner reservoirs37may be substantially the same, or one or more of the toner reservoirs37may hold different toner capacities. In one specific embodiment, the black toner reservoir has a higher capacity than the others. The toner reservoirs37may mount from a top16of the device10, and may detach during removal with the imaging units31remaining within the device10.

An intermediate transfer mechanism (ITO)60is disposed adjacent to each of the imaging units31. In this embodiment, the ITM60is formed as an endless belt trained about support rollers61,62and back-up roller63. Other embodiments may feature the ITM60as a drum that rotates past each of the PC drums34. During image forming operations, the ITM60moves past the imaging units31in a clockwise direction as viewed inFIG. 1. One or more of the PC drums34apply toner images in their respective colors to the ITM60. In one embodiment, a positive voltage field attracts the toner image from the PC drums34to the surface of the moving ITM60.

The ITM60rotates and collects the one or more toner images from the imaging nits31and then conveys the toner images to a media sheet at a second transfer area40. The second transfer area40includes a nip formed between the back-up roller63and a second transfer roller41. A cleaner unit20is positioned downstream from the second transfer area40to remove waste toner that remains on the ITM60.

A media path44extends through the device10for moving the media sheets through the imaging process. Media sheets are initially stored in the input tray68or introduced into the body12through a manual feed48. The sheets in the input tray68are picked by a pick mechanism67and into the media path44. In this embodiment, the pick mechanism67includes a roller positioned at the end of a pivoting arm. The roller rotates to move the media sheets from input tray68towards the second transfer area40. In one embodiment, the pick mechanism67is positioned in proximity (i.e., less than a length of a media sheet) to the second transfer area40with the pick mechanism67moving the media sheets directly from the input tray68into the second transfer area40. For sheets entering through the manual feed48, one or more rollers are positioned to move the sheet into the second transfer area40.

The media sheet receives the toner image from the ITM60at the second transfer area40. The media sheets with toner images are then moved along the media path44and into a fuser area70. Fuser area70includes fusing rollers or belts71that form a nip to adhere the toner image to the media sheet. The fused media sheets then pass through exit rollers45that are located downstream from the fuser area70. Exit rollers45may be rotated in either forward or reverse directions. In a forward direction, the exit rollers45move the media sheet from the media path44to an output area47. In a reverse direction, the exit rollers45move the media sheet into a duplex path46for image formation on a second side of the media sheet.

The cleaner unit20removes waste toner form the ITM60.FIG. 2illustrates one embodiment of the cleaner unit20that is positioned at the back-up roller63. A blade21abuts against the ITM60, removes the waste toner form the ITM60, and directs the accumulated waste toner into an opening26formed between the blade21and a lower seal25. The blade21contacts the ITM60at a position where the ITM60is in contact with the back-up roller63. The back-up roller63supports the ITM60to prevent sagging which would limit the effectiveness of the blade21to remove the waste toner. The blade21is positioned vertically above the back-up roller63, and downstream from the second transfer roller41relative to the direction of movement of the ITM60. In one embodiment, the back-up roller63includes a diameter that is less than about 27 mm. In one specific embodiment, the roller63includes a diameter less than about 25 mm.

The cleaner unit20may further include a bracket22that provides a support for attachment of the blade21. A housing23may form an interior space adjacent to the blade21. An auger24is positioned within the housing23. Auger24may include helical blades with rotation of the auger24causing the waste toner to be moved within the cleaner unit21. In one embodiment, the auger24leads into a waste toner reservoir (not illustrated) for storing the waste toner.

The bracket22may be mounted within the body12of the device10to position the cleaner unit20in proximity to the ITM60. The blade21is positioned to contact and remove the waste toner from the ITM60and direct it into an opening26formed between the blade21and a lower seal25. The opening26leads into the housing23that contains the waste toner. The auger24is positioned within the housing23to move the waste toner along the length of the cleaner unit20. In the embodiment ofFIG. 2, the auger is positioned vertically above the contact point of the blade21against the ITM60, and also above the opening26.

In use, the toner image is transferred to the media sheet as the sheet moves through the nip formed between the second transfer roller41and the back-up roller63. Some toner is not transferred to the media sheet and remains on ITM60after passing through the second transfer area40. The ITM60continues to rotate and the waste toner is brought into contact with the blade21. The blade21contacts and moves the waste toner form the ITM60and into the opening26formed between the blade21and the lower seal25. The lower seal25further keeps the waste toner that is cleaned from the ITM60inside the housing23. The waste toner is then moved by the auger24within the length of the housing23and to a storage reservoir.

In the embodiment ofFIG. 2, the cleaner unit20is positioned substantially inverted with the auger24positioned vertically above the blade21and the opening26. The opening26through which the waste toner enters into the housing23is facing downward in the direction of gravity. The cleaner unit20is further positioned away from the media path44to prevent the media sheet from contacting the cleaner unit20after passing through the second transfer area40. In one embodiment, the media path44ais a substantially straight line that extends directly between the nip formed between the fuser members71and the nip formed at the second transfer between the second transfer roller41and the back-up roller63. The cleaner unit20is offset from this media path44ato prevent inadvertent contact after the media sheets move beyond the second transfer area40. In one specific embodiment, the cleaner unit20is offset by about 2.14 mm from the media path44a. Other media paths44b,44cmay further be positioned and deflected further away from the cleaner unit20to prevent inadvertent contact.

As best illustrated inFIG. 1, the cleaner unit20may be positioned vertically above the ITM60, the back-up roller63, and the transfer roller41. The cleaner unit20may be positioned on a substantially horizontal section of the intermediate transfer member60and the transfer roller41is positioned on a substantially vertical section of the intermediate transfer member60.

Placement of the cleaner unit20on the back-up roller63is a cost saving measure as the back-up roller63can be used for multiple functions. Further, the back-up roller63has a generally large diameter that facilitates positioning of the cleaning blade21. In some embodiments, the diameter of the back-up roller63is between about 17 mm and 25 mm. Generally, a dedicated cleaning roller has about a 6 mm diameter making it more difficult to place the blade21.

In some embodiments, the cleaner unit20is used in combination with a dedicated cleaning roller69.FIG. 1illustrates an embodiment with the cleaner unit20positioned against a dedicated cleaning roller69. The cleaning roller69is positioned downstream from the back-up roller63.

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.