The invention relates generally to remanufactured toner cartridges, and particularly to methods and apparatus for cleaning the primary charge roller in a remanufactured laser printer toner cartridge.
Toner cartridges for laser printers are well known in the art. Generally, a cartridge will include sufficient toner for a large number of “typical” prints, such as 10,000 or 25,000, packaged in a housing which also contains those printing components that require periodic replacement, such as a photosensitive drum, magnetic and charging rollers, a “doctor” blade and a cleaning blade. The printing components and housing typically have a usable life, if properly cleaned and maintained, that greatly exceeds the number of prints for which toner is provided. Hence, toner cartridges are often remanufactured with a new supply of toner.
Remanufactured toner cartridges are both cost effective for consumers and environmentally sound. Original Equipment Manufacturers (OEMs) of printing equipment often provide “recycling” programs that allow consumers to return empty toner cartridges; the returned cartridges are shredded to recover some of the raw materials. Remanufacturing, in contrast, directly reuses most of the components of the cartridges, thereby greatly reducing the amount of material ending up in landfills, and having a substantially better “carbon footprint” than “recycling”.
In a typical laser printer, a revolving photosensitive drum or belt having a surface capable of holding a localized static charge is “charged” to a uniform voltage; a modulated laser is then scanned across the surface to remove the charge from those areas which are intended to be blank in the final image. A layer of toner, in the form of a fine powder, is formed on a developing roller or magnetic roller with a “doctor blade” and is then applied to the belt or drum; the toner adheres to those areas of the belt or drum that have retained a charge. The drum or belt then deposits the toner on a print medium (such as paper), and residual toner is wiped off the drum or belt by a “cleaning” or “wiper” blade.
In early generations of laser printers, the initial charge on the belt or drum was provided by corona wires. Newer printers typically use a roller mechanism, usually called the Primary Charge Roller (PCR), to charge the drum. The shift from corona wires to PCRs helped alleviate several problems associated with early laser printers, including high ozone emissions and “corona” streaks on prints attributed to the wires.
The PCR is generally a small diameter roller made of a compliant material, and having an outer surface adapted to transfer an electrostatic charge to the photosensitive drum. The PCR is held against the drum or belt, with the movement of the drum or belt causing to PCR to rotate. Typically, the primary charge roller is charged with both an alternating current signal, which functions to remove any residual or “ghost” static charges on the drum left from previous images, and a direct current bias, which functions to charge the surface of the drum or belt to a uniform voltage. The amplitude of the uniform direct current bias voltage to a large extent determines the darkness of the final prints.
Although replacement parts are generally readily available in the cartridge remanufacturing industry, it is common for cartridge remanufacturers to clean and reuse the cartridge's original PCR roller.
A challenge faced by toner cartridge remanufacturers is variability among components available for use in remanufactured cartridges. Components may be of varying ages, minor engineering changes may have been made between production runs of a cartridge, or it may be necessary to use a combination of refurbished parts and new replacement parts.
The toner used in a remanufactured cartridge can also vary from that used by the OEM. While the remanufacturer will typically specify a toner that essentially matches the important performance characteristics of the OEM toner, and therefore provides a print quality close to the OEM toner, toner formulations are complex, involving many production steps and constituents. Some aspects of the OEM toner may be covered by patents, or different toner additives may be used due to availability or cost.
The OEM has the ability to “fine tune” the printing system, including the components in the cartridge, the toner, and the operation of the printer itself, including various initialization and cleaning operations. The OEM may, for example, formulate the materials of the photosensitive drum, the cleaning blade, and PCR such that the printing system functions reliably for the number of prints provided by the original supply of toner, but not necessarily for the extended life of a refilled cartridge. The OEM may also utilize coatings or treatments on the components which are substantially degraded due to wear by the end of the original “life” of the cartridge.
The wear on components and differences in toner formulations may result in prints produced with a remanufactured cartridge exhibiting print defects over time. For example, prints may begin to show a gray background haze. Investigations have shown one cause of the haze to be a polymeric residue that forms on the PCR, apparently from toner additives, such as wax and cleaning agents.
Repeating defects may also appear which occur on the printed page at a frequency corresponding to the circumference of the PCR. These defects can be caused by small residual amounts of toner that are not removed from the photosensitive drum by the cleaning blade, and which are subsequently deposited on the PCR. Small spots of toner thus form on the PCR roller, which are compressed each time the spot contacts the photosensitive drum, rendering the spots essentially permanent. Since the portion of the drum contacted by the spot will not be properly charged, the resulting prints will show a recurring dark spot running down the page.
Some laser printer cartridges include PCR cleaning mechanisms, although in cartridges intended for a single use this may consist only of a simple strip of film which contacts the PCR roller. Experience with remanufactured cartridges show that a basic PCR cleaner of this nature is relatively ineffective in preventing the kind of print defects often observed with remanufactured cartridges.
There is thus a need for remanufactured toner cartridges which do not exhibit print defects attributable to PCR roller contamination, and methods.
The methods and apparatuses described below overcome drawbacks of known remanufactured printer cartridges by providing alternate methods and apparatus for directly removing the contaminants from the PCR, and thus to avoid or minimize printing defects associated with PCR contamination.
Embodiments include use of an added strip of material placed adjacent to the PCR that functions to wipe the PCR and remove contaminants, or use of a brush or squeegee to wipe the PCR and remove contaminants from the PCR.
These and other embodiments, features, aspects, and advantages of the invention will become better understood with regard to the following description, appended claims and accompanying drawings.
The foregoing aspects and the attendant advantages of the present invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
Reference symbols or names are used in the Figures to indicate certain components, aspects or features shown therein. Reference symbols common to more than one Figure indicate like components, aspects or features shown therein, although the components, aspects or features are not necessarily identical.
With reference to
The remanufacturing of laser printer toner cartridges typically entails disassembling spent cartridges, cleaning or replacing components as necessary, reassembling the cartridge, and refilling the cartridge with toner. Embodiments of the invention involve modifying the cartridge by the addition of a cleaning mechanism for the Primary Charge Roller (PCR).
Exemplary toner cartridge 200 is made up of multiple modules, which are typically separated during the remanufacture of the cartridge. The modules may, for example, include a toner hopper assembly 210, a magnetic roller section chassis 220, and a waste hopper assembly 230. Some cartridge types may consist of fewer modules; for example, the functions of the toner hopper and magnetic roller section may be combined into a single module. Various methods are typically used to join the modules, including mechanical fasteners and ultrasonic welding. In some exemplary toner cartridges the modules are also connected by cartridge end plates (not illustrated in
The toner hopper module 210 provides storage for a supply of fresh toner for the printer, which passes through an opening 218 in the hopper to the magnetic roller section chassis 220 for utilization by the printer. During printing, the magnetic roller 222 and “doctor” blade 224 mounted in the magnetic roller section chassis serve to meter toner received from the toner hopper onto the photosensitive drum 234 of the cartridge. Toner adheres to the rotating magnetic roller 222; the level of toner deposited on the magnetic roller and then the photosensitive drum is primarily controlled by a doctor blade 224.
The waste hopper assembly 230 of the exemplary toner cartridge includes a primary charge roller (PCR) 232, the photosensitive drum 234, a wiper blade 236, and a waste toner hopper compartment 238. In an exemplary toner cartridge, the waste hopper assembly may be retained to the other modules by the cartridge end plates, as discussed above. In operation, the photosensitive drum 234 receives an overall charge from the primary charge roller 232; portions of the drum are then selectively discharged by modulated light from a laser (denoted by the short-and-long dashed line 140), with the pattern of charged and discharged areas corresponding to the image to be printed. The photosensitive drum then rotates past the magnetic roller 222, and toner is selectively transferred to the drum based on the levels of localized charge on the drum. The photosensitive drum then rotates past the media path as print media is moved along the path; an electric charge on transfer roller 116, positioned on the opposite side of the print media, causes the toner on the drum to be attracted to print media.
A residue of toner may remain on the photosensitive drum 234 after the bulk of the toner is transferred to the print media; this residue is ideally removed from the drum by the wiper blade 236 and is deposited in the waste toner hopper compartment 238.
A typical toner cartridge includes additional components not discussed above, such as mechanisms for stirring the toner and for sensing toner levels; the above discussion is intended only to serve as an overview.
After toner is deposited on the print media, the print media is carried along the printer media path to a fuser where the toner is “fused” to the media by a heated fixing sleeve 118 and pressure roller 120. The printed media 304 is then deposited in output media tray 130.
An exemplary toner cartridge may be engineered to print a specified number of “typical” pages, such as 10,000 or 25,000 pages, after which the supply of toner is exhausted. When a cartridge is depleted of usable toner, it may be remanufactured to restore it substantially to original specifications. Remanufacturing the exemplary toner cartridge generally involves disassembly of the cartridge, cleaning, refurbishing, or replacing the individual components, reassembly of the cartridge, and refilling with toner.
Disassembly of the exemplary toner cartridge may begin with the separation of the waste hopper assembly 230 and related components from the remainder of the cartridge. This may involve the removal of cartridge end plates, as discussed above. The components within the waste hopper assembly, including the primary charge roller 232, the photosensitive drum 234, and the wiper blade 236, may then be removed for cleaning, refurbishing, or replacement.
Embodiments of the invention include modifying a laser printer cartridge to add a PCR cleaner. In embodiments of the invention the PCR cleaner is attached to the cartridge wiper blade assembly, and positioned such that the cleaner contacts the revolving PCR. The wiper blade may be a replacement wiper blade or a reused original wiper blade, as discussed below. The PCR cleaner is made of a material adapted to remove contaminants from the PCR, and is positioned to clean the PCR without substantially impeding the PCR's rotation.
Referring to
The L-shaped bracket 250 of the prior art waste wiper blade assembly may have a plastic spacer 252 adhered to its surface supporting a thin flexible film strip 254. When the wiper blade 236 is in position to clean the drum 234, the film strip 254 makes contact with the PCR 232 and provides limited cleaning of the PCR. The thin strip may, for example, be made of a material with triboelectric characteristics that allow it to “catch” stray incorrectly charged toner particles. As discussed above, the cleaning provided by the film strip has generally proven inadequate for preventing the type of PCR-related print defects observed with remanufactured cartridges, which may be due to different toner formulations and other system variables.
The foam strip 260 shown in
The foam strip 260 is fastened with any conventional means, such as an adhesive, to part of the wiper blade assembly shown as L-shaped mounting bracket 250. Mechanical fastening may also be used, such as, for example, screws or clips. Alternatively to the single layer shown at 260, the foam strip may be composed of a foam layer and an adhering layer, such as double-sided adhesive tape (not show), or may be part of an assembly which is mechanically fastened to the bracket (not shown). The foam strip 260 is positioned up against the PCR 232 with sufficient force to cause substantially all of the residual toner and toner additives on PCR 232 to be removed. As shown in
In an exemplary embodiment, bracket 250 and wiper blade 236 comprise a replacement wiper blade, as is known in the art, and the foam strip 260 is secured to the replacement blade prior to the installation of the wiper blade on the waste hopper assembly 230. In other embodiments, the bracket 250 and wiper blade 236 may comprise the original cartridge bracket and wiper blade; the foam strip may be adhered after the bracket and wiper blade have been removed from the cartridge for cleaning or other refurbishment.
The brush 270 is fastened to the L shaped mounting bracket 250 of the wiper blade assembly by any convention method, such as adhesive, double sided tape, or mechanical fasteners. The brush 270 is positioned up against the PCR 232 with sufficient force to cause essentially all of the residual toner on PCR 232 to be removed without degrading operation of the PCR or printer.
The squeegee 280 is fastened to the L-shaped wiper blade mounting bracket 250 of the wiper blade assembly by any conventional means, such as an adhesive, double sided tape, or mechanical fasteners. The squeegee 280 is positioned up against the PCR 232 with sufficient force to cause essentially all of the residual toner on PCR 232 to be removed. As shown in
The wiper blade assembly may vary in construction and design details from the wiper blade assembly shown in the accompanying Figures, and the method of attaching the PCR cleaner to the wiper blade assembly may similarly vary. The materials comprising the PCR cleaner include any materials which can perform the function of removing contaminants from the PCR without degrading PCR operation or printer performance. Embodiments of the invention are intended to include any PCR cleaner added to the wiper blade in a remanufactured laser printer cartridge which functions by contact with the rotating PCR.
Further, toner cartridges differ in design and construction, and in other embodiments of the invention the PCR cleaner may be fastened to another surface within the toner cartridge, such as, for example, directly to a portion of the waste toner hopper. Embodiments of the invention thus include the addition of a PCR cleaner that cleans by rubbing contact with the PCR, or by contact in which the cleaner compresses slightly against the PCR to remove contaminants, to a remanufactured cartridge, where the original cartridge lacked such a cleaner, regardless of how the PCR cleaner is mounted within the cartridge.
As discussed above, the PCR is caused to rotate by contact with the rotating photosensitive drum. Excessive friction of the cleaning element on the PCR could potentially cause a variety of printing problems, such as inducing the wiper blade to “flip” or excessive erosion of the PCR or drum coating. Positioning of the cleaning member with respect to the PCR in embodiments of the invention is thus selected to provide adequate cleaning of the PCR without substantially adding a rotational load to the PCR or unduly impacting PCR operation.
The vertical axis of
If the replacement wiper blade assembly (or reused original wiper blade assembly) includes a thin film strip intended to contact the PCR during operation, that film strip is removed 908. The wiper blade assembly is then modified 910 by the attachment of a PCR cleaning member to wiper blade assembly. The cleaning member in an exemplary embodiment is a foam strip; in other embodiments, the cleaning member may be a brush or a squeegee, or any other cleaning device that will function to remove contaminants from the PCR without interfering with the functioning of the PCR. The cleaning member may be attached to the wiper blade assembly by any convention method, such as an adhesive, double sided tape, or mechanical fasteners. The modified wiper blade assembly is then installed 912 in the cartridge, and the cartridge is reassembled 914. Reassembly of the cartridge may include using replacement parts for other components in the cartridge, as necessary, to ensure proper operation of the cartridge, and includes refilling the cartridge with a new supply of toner. The method then ends 916.
While an exemplary embodiment of the method includes the steps outlined above, other embodiments may follow an alternate sequence of steps or omit steps. For example, a cleaning member may be installed on a wiper blade assembly without physically removing the wiper blade assembly from the toner cartridge, or a cartridge may be obtained already in a disassembled state, or left disassembled after modification. It is the intent of the applicants that methods of the invention include all methods which result in the addition of a PCR cleaning member to the wiper blade assembly of a remanufactured laser printer toner cartridge, however achieved, as recited in the claims.
Although specific embodiments of the invention have been described, various modifications, alterations, alternative constructions, and equivalents are also encompassed within the scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that additions, subtractions, deletions, and other modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims.
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Number | Date | Country | |
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20110249983 A1 | Oct 2011 | US |