Patent Application
20080107462
The present disclosure is directed to flicker bars for contacting and flicking fibers of a moving member, and more particularly to such a flicker bar having a soft contact portion and a toner image reproduction machine having same.
In a typical toner image reproduction machine, for example an electrostatographic printing process machine, a sensitive photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas thereby forming an electrostatic latent image thereon corresponding to the informational areas contained within the original document.
After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a charged-developer material into contact with it. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. Thereafter, the toner particles are heated to permanently affix the powder image to the copy sheet.
The foregoing generally describes a typical black and white electrostatographic printing machine. With the advent of multicolor electrophotography, it is desirable to use an architecture that comprises a plurality of image forming stations. One example of the plural image forming station architecture utilizes an image-on-image (101) system in that the photoreceptive member is recharged, re-imaged and developed for each color separation. This charging, imaging, developing and recharging, re-imaging and developing, all followed by transfer to paper, is done in a single revolution of the photoreceptor in so-called single pass machines, while multi-pass architectures form each color separation with a single charge, image and develop, with separate transfer operations for each color. In each case, residual toner particles remaining on the surface of the photoconductive member must be cleaned off before reuse. The use of cleaning fiber brushes is well known in which brush fibers move or rotate into cleaning contact with the surface of the photoconductive member and remove and carry residual toner particles from such surface. In order to maintain the desired efficiency of the cleaning apparatus, toner particles so removed by the brush fibers must in turn be removed from the brush fibers.
In general as disclosed for examples in the following patents, it is well known to remove particles or molecules from moving fibers, such as the fibers of a cleaning brush, using a flicking action created in the moving fibers by a member or device, typically called a flicker bar, that is mounted across the path of movement of, and in an interference relationship with, the moving fibers.
U.S. Pat. No. 3,978,539, issued Sep. 7, 1976 and entitled “Floor sweeper with auxiliary rotary brushes” discloses a floor sweeper having, in addition to its main brush roller, one or more auxiliary brushes for sweeping debris into the path of the main brush. Each auxiliary brush includes a brush body having an annular array of outwardly downwardly inclined brush bristles. A flexible drive ring is mounted concentric to said bristles and adjacent the roots thereof on the underside of the brush body. Both the ring and bristle tips are disposed in fixed parallel planes and the assembly is mounted on an axis which is fixed and inclined from the vertical in a manner so that the rearward brush edge will, upon forward sweeper movement, rotate transversely inwardly beneath the sweeper housing with a debris disturbing and flicking action. Downward force on the sweeper causes the drive ring to deform upwardly and to deflect the adjacent bristles in a direction away from the carpet to keep the brush-carpet friction forces generally equalized.
U.S. Pat. No. 5,257,578 issued Nov. 2, 1993 and entitled “Device for automatically cleaning blanket cylinders in an offset printing press” discloses an automatic cleaning device for cleaning blanket cylinders in a web fed offset lithographic printing press. The device includes at least one brush roller for removing foreign matter from a blanket cylinder. The device also includes pneumatic cylinders which bring the brush roller into engagable contact with the blanket cylinder and the web. A flicker roller is also provided for flicking particles and other waste debris off the brush roller. In an engaged position, the brush roller, blanket cylinder and the web form an enclosed triangular region with the flicker roller being disposed within this region. This enables the device to be self-cleaning while at the same time prevents blanket wash waste from invading inker and dampening units.
U.S. Pat. No. 4,673,284, issued Jun. 16, 1987 and entitled “Cleaning device” discloses a cleaning device for removing the residual toner particles on the insulating surface in a two color printing apparatus includes a rotatable cleaning brush having two kinds of fiber materials charged the opposite polarities, and a flicker device is also provided for flicking the brush to remove toner particles therefrom as the brush rotates.
U.S. Pat. No. 4,304,026 Dec. 8, 1981 and entitled “Cleaning apparatus for a xerographic reproduction machine” discloses an improved cleaning apparatus for cleaning a photoreceptor in a xerographic reproduction machine includes a rotatably mounted circular cleaning brush and a flicker member within a housing. A portion of the flicker member is in contact with the brush to produce a primary flicking of the brush bristles as the brush rotates out of contact with this portion. Formed in this portion of the flicker member is an aperture in the form of a slot to produce a secondary flicking of the brush bristles as the brush rotates over this portion. The flicker member is contoured so that the angle between the tangents to the flicker member and brush roll surface at the point of initial contact is very small, approximately 5 degree, but gradually increases to a maximum of approximately 45 degree before the brush rotates out of contact with the flicker member. A vacuum chamber behind the flicker member communicates with a prenip region adjacent the periphery of the brush through a vacuum aperture formed in a portion of the flicker member not in contact with the brush. This causes a major portion of the air drawn from the exterior of the housing to be drawn through the brush into the prenip region and through the slot and vacuum aperture. An air inlet is formed in the housing adjacent to where the brush rotates out of contact with the flicker member to permit air to be drawn through the housing in the general direction of rotation of the brush.
Conventionally, flicker bars or the contact portions of flicker devices or flicker assemblies have been made from hard metals such aluminum and hard plastic materials such as Teflon, nylon, ABS and polyethylene (Teflon is a trademark of E.I. duPont de Nemours & Co., Inc. of Wilmington, Del.; Nylon is a trademark of The Dow Chemical Company, and ABS is a trademark of the Komet Stahlhalter-und Werkzeugfabrik Robert Breuning GmbH company). It has however been found that the use of such conventional flicker devices having hard contact portions for contacting and flicking heat sensitive particles, such as toner particles in electrostatographic reproduction machines, causes other problems. For example, in electrostatographic reproduction machines that use a sensitive photoreceptive imaging member, electrostatic imaging devices, heat sensitive toner particles to form images, and an imaging member cleaning apparatus including a cleaning fiber brush and a conventional flicker bar, hard crusty lumps of toner that inevitably buildup on the conventional flicker bars tend to become dislodged or to break off when impacted by moving cleaning fibers making contact therewith. The dislodged crusty lumps then undesirable get caught up or trapped in any nip between the sensitive photoreceptive imaging member and any device forming a nip therewith, and there tend to prematurely scratch and damage the sensitive photoreceptive imaging member.
In accordance with the present disclosure, in order to prevent built up crusts on the flicker assembly from being detrimentally dislodged due to the cleaning fibers impacting the flicker bar assembly, there is provided a soft contact portion flicker bar assembly for mounting in a machine to contact and flick the cleaning fibers moving along a fiber path. The soft contact portion flicker bar assembly includes (a) a base portion for mounting to a frame portion of the machine; (b) a body portion including a distal, first end, and an opposite, second end connected to the base portion; and (c) a tip portion connected to the first, distal end for contacting and interfering with cleaning fibers moving along the fiber path. The tip portion is made of a material having a Shore A durometer hardness of less than 85 for reducing a jarring effect of impact forces between such tip portion and the moving cleaning fibers, thereby preventing detrimental dislodging of built up crusts of particles from any part of the flicker bar assembly.
The foregoing and other features of the instant disclosure will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawings in that:
While the present disclosure will be described hereinafter in connection with a preferred embodiment thereof, it should be understood that it is not intended to limit the disclosure to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the disclosure as defined in the appended claims.
Referring first to
Initially, a portion of the photoconductive belt surface passes through charging station AA. At charging station AA, a corona-generating device indicated generally by the reference numeral 22 charges the photoconductive belt 10 to a relatively high, substantially uniform potential.
As also shown the reproduction machine 8 includes a controller or electronic control subsystem (ESS) 29 that is preferably a self-contained, dedicated minicomputer having a central processor unit (CPU), electronic storage, and a display or user interface (UI). The ESS 29, with the help of sensors and connections, can read, capture, prepare and process image data and machine status information.
Still referring to
ROS 30 includes a laser with rotating polygon mirror blocks. Preferably a nine-facet polygon is used. At exposure station BB, the ROS 30 illuminates the charged portion on the surface of photoconductive belt 10 at a resolution of about 300 or more pixels per inch. The ROS will expose the photoconductive belt 10 to record an electrostatic latent image thereon corresponding to the continuous tone image received from ESS 29. As an alternative, ROS 30 may employ a linear array of light emitting diodes (LEDs) arranged to illuminate the charged portion of photoconductive belt 10 on a raster-by-raster basis.
After the electrostatic latent image has been recorded on photoconductive surface 12, belt 10 advances the latent image through development stations CC, that include four developer units as shown, containing CMYK color toners, in the form of dry particles. At each developer unit the toner particles are appropriately attracted electrostatically to the latent image using commonly known techniques.
With continued reference to
Fusing station FF includes a fuser assembly indicated generally by the reference numeral 70 that permanently affixes the transferred toner power image to the copy sheet. Preferably, fuser assembly 70 includes a heated fuser roller 72 and a pressure roller 74 with the powder image on the copy sheet contacting fuser roller 72. The pressure roller is crammed against the fuser roller to provide the necessary pressure to fix the toner powder image to the copy sheet. The fuser roll is internally heated by a quartz lamp (not shown). Release agent, stored in a reservoir (not shown), is pumped to a metering roll (not shown). A trim blade (not shown) trims off the excess release agent. The release agent is transferred to a donor roll (not shown) and then to the fuser roll 72.
The sheet then passes through fuser 70 where the image is permanently fixed or fused to the sheet. After passing through fuser 70, a gate 88 either allows the sheet to move directly via output 17 to a finisher or stacker, or deflects the sheet into the duplex path 100. Specifically, the sheet when to be directed into the duplex path 100, is first passed through a gate 134 into a single sheet inverter 82. That is, if the second sheet is either a simplex sheet, or a completed duplexed sheet having both side one and side two images formed thereon, the sheet will be conveyed via gate 88 directly to output 17. However, if the sheet is being duplexed and is then only printed with a side one image, the gate 88 will be positioned to deflect that sheet into the inverter 82 and into the duplex loop path 100, where the sheet is inverted and then fed to acceleration nip 102 and belt transports 110, for recirculation back through transfer station DD and fuser 70 for receiving and permanently fixing the side two image to the backside of that duplex sheet, before it exits via exit path 17.
After the print sheet is separated from photoconductive surface 12 of belt 10, residual toner/developer and paper fiber particles that is still on and may be adhering to photoconductive surface 12 are then removed therefrom at cleaning station EE in accordance with the present disclosure. Cleaning station EE as illustrated includes a cleaning apparatus 300 for removing and taking away residual particles from the photoreceptor surface 12.
Referring now to
As further illustrated in
The base portion 402 may be made of a metallic material such as aluminum. The mid or body portion can be made of any functionally acceptable material, including the same material used for the tip portion. The tip portion 406 as such is made of a non-metallic material. In cleaning apparatus for toner image reproduction machines, such material of course should be selected so that it does not interact with the toner particles. As pointed out above, such materials, although conventionally being hard and thus each having a Shore A durometer hardness of greater than 95, for example a Shore D of 72 in some cases, have included Nylon, Teflon, ABS and polyethylene. To the extent that relatively softer (that is having a Shore A durometer hardness of less than 95) can be made, these materials in that form would be very suitable.
In accordance to the present disclosure, a preferred material for the tip portion is polyurethane. The polyurethane material accordingly would have a Shore A durometer hardness of less than 95, and preferably within a range of 50-85, more specifically within a range of 67-77, and in one example, a Shore A durometer hardness of 72. The body portion 404, and tip or soft contact portion 406 of the flicker bar assembly 400, 401 may be formed integrally as by molding. It is believed that the softer urethane material (50-85 Shore A) contact portion of the flicker bar assembly 400, 401, because it is relatively more compliant than conventional flicker bars, acts to cushion fiber impact, thus reducing the brush fiber impact energy.
This reduction in the impact energy advantageously prevents toner crusts that inevitably build up over time on parts of the flicker bar assembly and/or the fibers, from being jarred and becoming dislodged. As is well known, such dislodged crusts undesirably end up scratching and prematurely damaging machine parts, particularly the photoreceptor. The reduction in impact energy also is believed to extend the flicker bar wear life. Furthermore, it is believed that the relatively lower impact energy also reduces the heat generated on the impacted surfaces and thereby reduces heat caused buildup of toner particles on the flicker bar surfaces for example. As such, the soft contact portion flicker bar assembly of the present disclosure will find suitable application in any machine that handles heat sensitive material, such as powder toners, and that uses a brush cleaner apparatus to clean any of the material handling surfaces therein.
Thus, in order to prevent built up crusts on the flicker assembly from being detrimentally dislodged due to the cleaning fibers impacting the flicker bar assembly, there is provided a soft contact portion flicker bar assembly for mounting in a machine to contact and flick the cleaning fibers moving along a fiber path. The soft contact portion flicker bar assembly includes (a) a base portion for mounting to a frame portion of the machine; (b) a body portion including a distal, first end, and an opposite, second end connected to the base portion; and (c) a tip portion connected to the first, distal end for contacting and interfering with cleaning fibers moving along the fiber path. The tip portion is made of a material having a Shore A durometer hardness of less than 85 for reducing a jarring effect of impact forces between such tip portion and the moving cleaning fibers, thereby preventing detrimental dislodging of built up crusts of particles from any part of the flicker bar assembly.
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. Also that 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. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
