Patent Application
20080038012
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.
A first toner transfer area 30 includes one or more imaging units 31 that are aligned horizontally extending from the front 13 to a back 15 of the body 12. Each imaging unit 31 includes a charging roll 32, a developer roll 33, and a rotating photoconductive (PC) drum 34. The charging roll 32 forms a nip with the PC drum 34, and charges the surface of the PC drum 34 to a specified voltage such as −1000 volts, for example. A laser beam 35 from a printhead 36 contacts the surface of the PC drum 34 and discharges those areas it contacts to form a latent image. In one embodiment, areas on the PC drum 34 illuminated by the laser beam 35 are discharged to approximately −300 volts. The developer roll 33, which also forms a nip with the PC drum 34, then transfers toner particles from a toner reservoir 37 to the PC drum 34 to form a toner image. The toner particles are attracted to the areas of the PC drum 34 surface discharged by the laser beam 35.
A toner reservoir 37 is operatively connected to each of the imaging units 31. The toner reservoirs 37 are sized to contain toner that is transferred to the imaging units 31 for image formation. The toner reservoirs 37 may be mounted and removed from the device 10 independently from the imaging units 31. In one embodiment, the toner reservoirs 37 each contain one of black, magenta, cyan, or yellow toner. Each of toner reservoirs 37 may be substantially the same, or one or more of the toner reservoirs 37 may hold different toner capacities. In one specific embodiment, the black toner reservoir has a higher capacity than the others. The toner reservoirs 37 may mount from a top 16 of the device 10, and may detach during removal with the imaging units 31 remaining within the device 10.
An intermediate transfer mechanism (ITO) 60 is disposed adjacent to each of the imaging units 31. In this embodiment, the ITM 60 is formed as an endless belt trained about support rollers 61, 62 and back-up roller 63. Other embodiments may feature the ITM 60 as a drum that rotates past each of the PC drums 34. During image forming operations, the ITM 60 moves past the imaging units 31 in a clockwise direction as viewed in
The ITM 60 rotates and collects the one or more toner images from the imaging nits 31 and then conveys the toner images to a media sheet at a second transfer area 40. The second transfer area 40 includes a nip formed between the back-up roller 63 and a second transfer roller 41. A cleaner unit 20 is positioned downstream from the second transfer area 40 to remove waste toner that remains on the ITM 60.
A media path 44 extends through the device 10 for moving the media sheets through the imaging process. Media sheets are initially stored in the input tray 68 or introduced into the body 12 through a manual feed 48. The sheets in the input tray 68 are picked by a pick mechanism 67 and into the media path 44. In this embodiment, the pick mechanism 67 includes a roller positioned at the end of a pivoting arm. The roller rotates to move the media sheets from input tray 68 towards the second transfer area 40. In one embodiment, the pick mechanism 67 is positioned in proximity (i.e., less than a length of a media sheet) to the second transfer area 40 with the pick mechanism 67 moving the media sheets directly from the input tray 68 into the second transfer area 40. For sheets entering through the manual feed 48, one or more rollers are positioned to move the sheet into the second transfer area 40.
The media sheet receives the toner image from the ITM 60 at the second transfer area 40. The media sheets with toner images are then moved along the media path 44 and into a fuser area 70. Fuser area 70 includes fusing rollers or belts 71 that form a nip to adhere the toner image to the media sheet. The fused media sheets then pass through exit rollers 45 that are located downstream from the fuser area 70. Exit rollers 45 may be rotated in either forward or reverse directions. In a forward direction, the exit rollers 45 move the media sheet from the media path 44 to an output area 47. In a reverse direction, the exit rollers 45 move the media sheet into a duplex path 46 for image formation on a second side of the media sheet.
The cleaner unit 20 removes waste toner form the ITM 60.
The cleaner unit 20 may further include a bracket 22 that provides a support for attachment of the blade 21. A housing 23 may form an interior space adjacent to the blade 21. An auger 24 is positioned within the housing 23. Auger 24 may include helical blades with rotation of the auger 24 causing the waste toner to be moved within the cleaner unit 21. In one embodiment, the auger 24 leads into a waste toner reservoir (not illustrated) for storing the waste toner.
The bracket 22 may be mounted within the body 12 of the device 10 to position the cleaner unit 20 in proximity to the ITM 60. The blade 21 is positioned to contact and remove the waste toner from the ITM 60 and direct it into an opening 26 formed between the blade 21 and a lower seal 25. The opening 26 leads into the housing 23 that contains the waste toner. The auger 24 is positioned within the housing 23 to move the waste toner along the length of the cleaner unit 20. In the embodiment of
In use, the toner image is transferred to the media sheet as the sheet moves through the nip formed between the second transfer roller 41 and the back-up roller 63. Some toner is not transferred tot he media sheet and remains on ITM 60 after passing through the second transfer area 40. The ITM 60 continues to rotate and the waste toner is brought into contact with the blade 21. The blade 21 contacts and moves the waste toner form the ITM 60 and into the opening 26 formed between the blade 21 and the lower seal 25. The lower seal 25 further keeps the waste toner that is cleaned from the ITM 60 inside the housing 23. The waste toner is then moved by the auger 24 within the length of the housing 23 and to a storage reservoir.
In the embodiment of
As best illustrated in
Placement of the cleaner unit 20 on the back-up roller 63 is a cost saving measure as the back-up roller 63 can be used for multiple functions. Further, the back-up roller 63 has a generally large diameter that facilitates positioning of the cleaning blade 21. In some embodiments, the diameter of the back-up roller 63 is 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 blade 21.
In some embodiments, the cleaner unit 20 is used in combination with a dedicated cleaning roller 69.
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 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.
