BRIEF DESCRIPTION OF THE DRAWINGS
In FIG. 1, an embodiment of a marking system using a cleaning brush and the cleaning blade of this invention is illustrated.
In FIG. 2, an embodiment of a marking system using two cleaning brushes and the cleaning blade of this invention is illustrated.
In FIG. 3, the elastomeric cleaning blade of this invention (in a non-brush system) as it contacts a photoreceptor or photoconductive belt is illustrated. The carbon nanotubes are embedded throughout the elastomer.
In FIG. 4, the carbon nanotubes are dispersed primarily on the front tip of the brush, as illustrated.
In FIG. 5, a spots blade is shown for use in a cleaning system of this invention.
On FIG. 6, the carbon nanotubes are dispersed primarily along the bottom edge of the blade.
DETAILED DISCUSSION OF DRAWINGS AND PREFERRED EMBODIMENTS
The use of embodiments of the blades of this invention are described in the following figures:
In FIG. 1, cleaning system 1 of an embodiment, a photoconductive belt 2 is shown as it is adapted to move sequentially first to the cleaning blade 3 and then to an electrostatic brush 4. The elastomeric cleaning blade 3 incorporates carbon nanotubes, the nanotubes comprising no more than about 60% by weight of the entire blade. The arrows 11 show the direction and path of the PC belt 2. The blade 3 is therefore upstream from the brush 4 and is the first cleaning component that contacts the belt. In this position, blade 3 gets the proper toner induced lubrication since toner has not been previously removed by a brush 4 or any other component. The electrostatic brush 4 has a charge on it that is opposite to the charge on the toner 5 used in the system. This will permit brush 4 to attract the opposite charged toner 5 and remove any residual toner 5 not removed from the PC belt 2 by the cleaning blade 3. As above stated, since the cleaning blade 3 is the first cleaning component contacted by the belt 2, there is sufficient toner 5 on the belt at that point to provide ample lubrication for the blade 3 and minimize abrasion of the belt 2. The electrostatic brush 4 in system 1 follows the blade 3 to remove any residual toner 5. In an embodiment, a vacuum unit 6 is positioned between the blade 3 and brush 4 to vacuum off any loose toner removed by either blade 3 and brush 4. After the toner is vacuumed out it can be disposed of by any suitable method. Vacuum air channels 7 and 8 are in air flow contact with the blade 3 and brush 4, respectively. A flicker bar 9 is in operative contact with brush 4 and is adapted to de-tone brush 4 together with vacuum unit 6. As toner 5 is flicked off brush 4 by flicker bar 9, it is picked up by the suction of vacuum channel 8 and transported out of system 1. Flicker bar 9 is positioned such that the fibers in the rotation brush 4 will contact the flicker bar 9 prior to reaching the vacuum channel 8. In FIG. 1, the flicker bar 9 is shown in a position consistent with a counterclockwise brush 4 rotation. Clockwise brush 4 rotation can also be used with the flicker bar 9 in a suitable position. An entry shield 10 is located below the cleaning blade 3 and directs loosened toner into vacuum channel 7 for removal from system 1. Toner 5, therefore, is sequentially removed from photoconductor belt 2 by first contact with blade 3 which scrapes toner 5 off belt 2 and then by cleaner brush 4 which removes any residual toner by brush action together with electrostatic action (since it is biased oppositely to toner). The arrows 11 indicate the travel direction of belt 2, blade 3 is “upstream” and brush 4 is “downstream” as used in this disclosure. By this continuous contact with the photoconductive belt 2, the blade 3 in the prior art becomes worn and torn at the blade edges which significantly reduces the effective life of the blade. With the carbon nanotube containing blades 3 of this invention up to 0.5% to about 60% by weight, the blade 3 life is significantly increased. The nanotubes addition significantly increases the electrical conductivity and thermal conductivity of the blade 3. This enhanced electrical conductivity can dissipate charge accumulation at the blade 3 due to rubbing against the photoreceptor 2. The enhanced thermal conductivity can aid heat dissipation due to friction at the blade-photoreceptor interface.
In FIG. 2, a second embodiment of the cleaning system described herein is illustrated. Two brushes 14 and 15 are used and a cleaning blade 3 is positioned adjacent to the first brush 14. The first brush 14 is charged in a manner that allows ample toner 5 to pass through to the blade tip 3, thus ensuring adequate lubrication at all times. A negative charge on the first brush 14 would remove any toner 5 that acquired a positive charge and allow all of the negatively charged toner 5 to pass through to the blade tip 3. Alternatively, a low positive charge on the first brush 14 would enable some level of cleaning of negatively charged toner 5 from the PC belt 2, if so desired, depending on the operating conditions at a given point in time. In either case, positive or negative charging of the first brush 14, the charge level would be such that ample toner is allowed to pass through to the blade tip 3. The first brush 14 is also used to transport toner 5 from the blade tip 3 to the vacuum channel 16. Another vacuum channel 17 is used to transport any residual loosened toner 5 from the second brush 15 to a vacuum collection means where it is disposed of. The second brush 15 can be charged positively or negatively to complement the polarity of the first brush 14. If the first brush 14 is negative to remove positively charged toner 5, the second brush 15 is positive to remove negatively charged toner 5 that was not removed by the blade tip 3. If the first brush 14 is positive to remove some negative toner 5, the second brush is negative to remove positively charged toner 5 that is not removed by the blade tip 3. If the Xerographic system is optimized in a manner to ensure only one polarity of toner arrives at the cleaning system 1, then both brushes 14 and 15 can be charged to the same polarity, that being opposite of the toner 5 polarity. The charge level on the first brush 14 would still be such that an ample amount of lubricating toner 5 would pass through to the blade tip 3. The flicker bars 18 positions are suitable for brushes that are rotating in a counterclockwise direction. The brush fibers hit the flicker bar 18 which compresses the fibers. Then as the fibers open up, they are exposed to the vacuum channels 16 and 17 for toner removal. Obviously, if the brushes 14 and 15 were rotating clockwise, the flicker bars 18 would be shown in a different location (preceding the vacuum channels 16 and 17). An entry shield 10 is positioned below the first brush 14 to capture loose toner 5 falling from the brush 14 or blade 3 of this invention. Unloaded polyurethane is typically used for cleaning blade materials. Obviously, other elastomeric materials may be used if suitable such as natural or synthetic rubbers. The small percentage of carbon nanotubes incorporated into the elastomer or polyurethane (either randomly or in a pattern) will improve the robustness of the elastomer without significantly compromising the desired elastomeric properties of blade 3.
In FIG. 3, the cleaning blade 3 of an embodiment is shown in an expanded view as it contacts PC belt 2. In FIG. 3 the carbon-nanotube random distribution with laminated blade is made by centrifugal casting. This blade 3 incorporates carbon nanotubes 19 throughout the elastomer 20 at about 1-60% by weight. A movable or floating support 12 for the cleaning blade 3 permits proper movement and support for blade 3 as it contacts PC belt 2. While any suitable angle of contact 13 between the PC belt 2 and the blade 3 may be used, an angle of from 5 to 30 degrees has been found to be effective, however, any suitable and effective angle may be used. This blade 3 of FIG. 3 and FIG. 4 can be used in the embodiments of FIGS. 1 and 2 and any other suitable embodiments. Any suitable amount of carbon nanotubes 19 may be used in blade 3 of FIGS. 3 and 4. An amount of 0.5-2.0% in one embodiment has been found to be very useful. This FIG. 3 also illustrates a cleaning station portion where only the cleaning blade 3 is used without cleaning brushes 14 and 15. The blade 3 of FIG. 4 is molded and used in the same embodiment or cleaning system as FIG. 3 except that in the molded blade 3 of FIG. 4 the nanotubes 19 are only dispersed at the front tip portion 22 of blade 3, whereas in FIG. 3 the nanotubes are randomly or pattern-wise dispersed throughout the entire blade or elastomer 20. In FIG. 3, the nanotubes 19 are dispersed randomly whereas in FIG. 4 the carbon nanotubes 19 are dispersed in a pattern or evenly spaced as it is molded. Obviously, the nanotubes 19 can be dispersed either way throughout the blade 3 (as in FIG. 3) or can be dispersed either way at the tip 22 of blade 3 (as in FIG. 4). In FIG. 5 a spots blade 21 is shown in a cleaning system. This spots blade 21 can be used, if suitable, alone or with the cleaning blade 3 as shown in FIG. 1. However, generally, the blade-brush cleanings shown in FIG. 1 and FIG. 2 do not require spots blades since the cleaning blade 3 will remove most film material. The spots blade 21 will have the same carbon-nanotube distribution and configuration as the cleaning brushes 3 of FIGS. 3 and 4.
In FIG. 6 an embodiment is shown where the carbon nanotubes 19 are dispersed primarily along the bottom edge 23 of blade 3. This blade would be manufactured by a centrifugal casting process (a common manufacturing process). A layer of nanotube 19 filled blade material would be cast on top of unfilled material layer 20 to form a laminate. When cured and cut to size, the nanotube filled layer of the laminate would be used as the cleaning edge of the blade. Therefore the nanotubes 19 can be randomly dispersed or distributed in elastomer 20, or can be evenly dispersed in elastomer 20. The nanotubes 19 may be located in the blade 3 throughout (FIG. 3) or in the bottom portion of the blade (FIG. 6) or in a front tip portion of the blade 3 (FIG. 4).
The configurations illustrated in the figures above are not limiting to the present disclosure. Any suitable marking system using a cleaning blade may use the nanotube containing enhanced durable cleaning blade of this invention.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
Patent Application
20080025775
