Patent Publication Number: US-7715776-B2

Title: Dual blade cleaning system

Description:
BACKGROUND 
   Disclosed in embodiments herein are systems for cleaning an image forming device photoreceptor, and more specifically a dual blade cleaning system utilizing three-pivot links for moving the blades between separate Suspended Positions and a common Cleaning Position. 
   In electrophotographic applications such as xerography, a charge retentive photoreceptor belt or drum is electrostatically charged according to the image to be produced. In a digital printer, an input device such as a raster output scanner controlled by an electronic subsystem can be adapted to receive signals from a computer and to transpose these signals into suitable signals so as to record an electrostatic latent image corresponding to the document to be reproduced on the photoreceptor. In a digital copier, an input device such as a raster input scanner controlled by an electronic subsystem can be adapted to provide an electrostatic latent image to the photoreceptor. In a light lens copier, the photoreceptor may be exposed to a pattern of light or obtained from the original image to be reproduced. In each case, the resulting pattern of charged and discharged areas on photoreceptor form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. 
   The electrostatic image on the photoreceptor may be developed by contacting it with a finely divided electrostatically attractable toner. The toner is held in position on the photoreceptor image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original beam reproduced. Once each toner image is transferred to a substrate, and the image affixed thereto form a permanent record of the image to be reproduced. In the case of multicolor copiers and printers, the complexity of the image transfer process is compounded, as four or more colors of toner may be transferred to each substrate sheet. Once the single or multicolored toner is applied to the substrate, it is permanently affixed to the substrate sheet by fusing so as to create the single or multicolor copy or print. 
   Following the photoreceptor to substrate toner transfer process, it is necessary to at least periodically clean the charge retentive surface of the photoreceptor. In order to obtain the highest quality copy or print image, it is generally desirable to clean the photoreceptor each time toner is transferred to the substrate. In addition to removing excess or residual toner, other particles such as paper fibers, toner additives and other impurities (hereinafter collectively referred to as “residue”) may remain on the charged surface of the photoreceptor. 
   The present application provides a new and improved apparatus for cleaning an image forming device moving surface, such as a photoreceptor surface, which overcomes at least the above-described problems. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view illustrating the cleaning system having a Doctor Blade arrangement as described herein with a first cleaning blade disposed in the Cleaning Position; 
       FIG. 2  is a perspective view illustrating the cleaning system having a Doctor Blade arrangement as described herein with a second cleaning blade disposed in the Cleaning Position; 
       FIG. 3  illustrates the Doctor Blade orientation of the first and second blades disposed in the Cleaning Position; 
       FIG. 4  illustrates the Doctor Blade orientation of the first and second blades disposed in the Cleaning Position; 
       FIG. 5  is a perspective view illustrating the cleaning system having a Wiper Blade arrangement as described herein with a first cleaning blade disposed in the Cleaning Position; 
       FIG. 6  is a perspective view illustrating the cleaning system having a Wiper Blade arrangement as described herein with a second cleaning blade disposed in the Cleaning Position; 
       FIG. 7  illustrates the Wiper Blade orientation of the first and second blades disposed in the Cleaning Position; and 
       FIG. 8  illustrates the Wiper Blade orientation of the first and second blades disposed in the Cleaning Position. 
   

   DETAILED DESCRIPTION 
   With reference to  FIG. 1 , an image forming device is shown generally at  10 . The image forming device  10  can be a copier, such as a xerographic copier, a printer, multifunction device or other device having a photoreceptor  12  for forming an image on a substrate such as for example paper (not shown). The photoreceptor  12  can be a drum photoreceptor  12   a , a flat rigid photoreceptor  12   b  (shown in  FIG. 3 ) or a belt photoreceptor  12   c  (shown in  FIG. 4 ), or other photoreceptor, having a moving surface  14  which moves in an operational direction shown generally by arrow  15 . 
   The image forming device  10  includes a cleaning system, shown generally at  16 , for cleaning toner particles, residue and other materials from a moving surface  14 , such as a photoreceptor surface  14 . Though some examples provided describe a system for cleaning moving photoreceptor surfaces  14 , the system  16  can also clean other image forming device moving surfaces, including but not limited to moving transfer surfaces such as biased transfer belts, biased transfer rolls, or intermediate transfer belts, examples of which can also be illustrated generally using the surfaces  14  depicted in  FIGS. 3 ,  4 ,  7  and  8 . Thus, the image forming device surfaces suitable for cleaning by the system  16  shall be referred to generally as moving surface  14 . 
   The cleaning system  16  can be contained in a removable cartridge housing  17 , if so desired, such as for example part of a print cartridge, also referred to a Xerographic Replaceable Unit (XRU). The XRU can be removed from the image forming device  10  and discarded when its useful life has been depleted. 
   The cleaning system  16  includes a first cleaning blade  20  having a cleaning blade member  22  extending from a blade holder  24  and terminating in an end  29 . The cleaning system  16  also includes a second cleaning blade  40  having a cleaning blade member  42  extending from a blade holder  44  and terminating in an end  49 . The cleaning blade members  22 ,  42  have upstream sides  22   a ,  42   a  and downstream sides  22   b ,  42   b  (shown in  FIGS. 3 and 4 ) as referenced to the operational direction of surface travel  15 . The cleaning blade members  22 ,  42  can be formed of a compliant material, such as polyurethane, which enable the blade members to bend or deflect when moved into cleaning contact with the moving surface  14  as described in further detail below. 
   Referring now to  FIG. 3 , the cleaning blades members  22 ,  42  include a cleaning tip, also referred to as a cleaning edge,  30  and  50  respectively, which is brought into cleaning contact with the moving surface  14  for cleaning same when the cleaning blades  20 ,  40  are moved into the Cleaning Position as shall be described in further detail below. The cleaning tips  30 ,  50  are formed between the blade member sides  22   b ,  42   b  and ends  29 ,  49  which meet at an angle β. For the purposes of the examples provided herein, β is 90 degrees, though it can be different. The cleaning tips  30 ,  50  can be coated with PMMA, SureLube, toner or other initial blade lubricant to prevent blade flip as the blades are moved into the Cleaning Position. 
   The blade holders  24 ,  44  can be formed of a rigid material such as aluminum, steel, other metals, composite plastics or other suitable rigid materials. They are elongated members having oppositely disposed lateral ends  26 ,  46  and  28 ,  48  respectively. The blade holders  24 ,  44  are disposed adjacent the moving surface  14 , extending laterally across it at an approximate right angle to the operational direction  15 . The blade holders  24 ,  44  have proximate portions  32 ,  52  and distal portions  34 ,  54 , respectively, as referenced in relation to the adjacent photoreceptor  12 . 
   The cleaning system  16  includes a pair of first links  60  formed of a rigid material, such as metal, plastic, composites or the like. The first links  60  are connected to opposite lateral ends of the cleaning blades  20  and  40  to couple the cleaning blade together for moving one blade member into the Cleaning Position while simultaneously moving the other blade into a corresponding Suspended Position, as shall be described in further detail below. The first links  60  are similar, unless stated below, and thus only one first link is shown in detail for the purposes of clarity. The first links  60  include first pivot connections  62  pivotally connected to the distal portions  34  of the oppositely disposed lateral ends  26  and  28  of the first blade holder  24 . The first links  60  also include second pivot connections  64  pivotally connected to the distal portions  54  of the lateral ends  46  and  48  of the second blade holder  44 . The first links  60  also include third pivot connections  66  pivotally connected to one or more frame members  67 , enabling the first links to rotate about a fixed axis A while preventing non-pivoting displacement of the first links with respect to the frame. The frame  67  can be part of the cartridge  17 , or a support member attached to the image forming device  10 . 
   The cleaning system  16  also includes a pair of second links  70  formed of a rigid material, such as metal, plastic, composites or the like. The second links  70  are connected to opposite lateral ends of the cleaning blades  20  and  40  to also couple the cleaning blade members together as shall be described in further detail below. The second links  70  are similar, unless stated below, and thus only one second link is shown in detail for the purposes of clarity. The second links  70  include first pivot connections  72  pivotally connected to the proximate portions  32  of the oppositely disposed lateral ends  26  and  28  of the second blade holder  24 . The second links  70  also include second pivot connection  74  pivotally connected to the proximate portions  52  of the lateral ends  46  and  48  of the second blade holder  44 . The second links  70  also include third pivot connections  76  pivotally connected to one or more of the frame members  67 ′, enabling the second links to rotate about a fixed axis B. The frame members  67 ′ can be the same as those described above at  67 , or different ones. 
   The first and second link pivot connections  62 ,  64 ,  66 ,  72 ,  74 , and  76  can be formed by fasteners, such as rivets, bolts or the like extending from the blade holders  24 ,  44  or frame  67 , and through apertures in the first and second links  60 ,  70 , or in other manners which enable relative rotation at the connections. The pivot connections  62 ,  64  and  66  are disposed in a triangular arrangement on the first links  60 , and the pivot connections  72 ,  74  and  76  are disposed in a triangular arrangement on the second links  70 . The first and second links  60 ,  70  can be V-shaped, each having 2 legs extending from the third pivot connections  66 ,  76  with the first pivot connections  62 ,  72  and second pivot connections  64 ,  74  disposed at the ends thereof, as shown in  FIGS. 1 and 2 . Such an arrangement can enable the links to be located close to each other without interfering in their movement. Other examples of the links  60 ,  70  can have triangular shapes with the pivot connections disposed at the vertices thereof. Other examples of the links can have other shapes. 
   An actuator  94 , as shown in  FIG. 2 , can be connected to one of the first links  60  to rotate it about the third pivot connection  66 . The actuator  94  can be a solenoid, or stepper motor, or some other actuator capable of rotating the first link  60  at connection  66 . The actuator  94  can be disposed at the third pivot connection  66 , or it can be disposed in another location and connected to the first link  60 , such as by gears, arms, etc. so as to provide rotational movement to the first link  60 . Other actuator arrangements capable of rotating the first and second links  60  and  70  about the third pivot connections,  66  and  76  respectively, are contemplated including, but not limited to using an actuator, shown at  95 , connected to one of the second links  70  to rotate it about the third pivot connection  76 , or two actuators  94  connected to each of the first links  60  or two actuators  95  connected to each of the second links  70  for rotating them about the third pivot connections  66  and  76  respectively. The first or second link driven by the actuator  94  or  95 , for rotation can be referred to as the drive link, whereas the undriven link can be referred to as the follower link. 
   The operation of the cleaning system  16  shall now be described. For the purposes of simplicity, an example of the cleaning system  16  is provided using one actuator  94  connected to one of the first links  60 , though it should be appreciated that operational movement of the cleaning blades  20 ,  40  as described herein can be extended to other arrangements of actuators as contemplated above. 
   At the end of the operational life of the first cleaning blade  20 , the used blade is withdrawn from contact with the moving surface  14  and the second blade  40  is placed into operation in the Cleaning Position. The actuator  94  drives the first link  60  providing pivoting movement of the pair of first links  60  about the third pivot connections  66  at axis A. As the first links  60  are rotated about axis A, the second links  70  also rotate at the third pivot connections  77  about axis B. Upon actuation of the actuator  94 , the cleaning blades  20  and  40  are alternately moved between separate Suspended Positions, disposed at different locations, and the common Cleaning Position, disposed at a single location, for cleaning the moving surface  14 . Only one of the cleaning blades  20  and  40  will be disposed in the Cleaning Position at a time, during which time the other blade will be disposed in its respective Suspended Position with the blade member separated from the moving surface  14 , as described in further detail below. 
   The cleaning blade system  16  can be provided in a Doctor Blade embodiment, as shown in  FIGS. 1 and 2 , wherein the cleaning blades  20 ,  40  are in a Doctor Blade orientation when disposed in the Cleaning Position, referred to herein as CP DB , as described in  FIGS. 3 and 4 . Alternatively, cleaning blade system  16 ′ can be provided in a Wiper Blade arrangement, as shown in  FIGS. 5 and 6 , wherein the cleaning blades  20 ′ and  40 ′ are in a Wiper Blade orientation when disposed in the Cleaning Position, referred to herein as CP WB , as described in  FIGS. 7 and 8 . 
   As shown in  FIG. 1 , the first cleaning blade  20  is in the Doctor Blade Cleaning Position CP DB  such that the first blade member cleaning tip  30  is in cleaning contact with the moving surface  14  in a Doctor Blade orientation. The second cleaning blade  40  is in its respective Suspended Position such that the cleaning tip  50  is separated from the moving surface  14 , as shown. The actuator  94  moves the drive link rotating it about the third pivot connection thereby rotating the drag link about its corresponding third connection also, to move the first cleaning blade  20  from the CP DB  to its respective Suspended Position as shown in  FIG. 2 . Simultaneously, the second cleaning blade  40  is moved from its Suspended Position into the same CP DB  at the same location previously occupied by the first blade  20 ′ such that the second blade member cleaning tip  50  is in cleaning contact with the moving surface  14  in the Doctor Blade Orientation. 
   Referring now to  FIG. 3  the Doctor Blade orientation for cleaning blades  20  and  40  disposed in CP DB  for a curved moving surface  14 , such as a drum photoreceptor  12   a , and for a flat rigid moving surface  14 , such as a flat photoreceptor  12   b , is shown generally at  300 . For the purposes of this description, a tangent T PR  is taken at curved moving surface which can be considered as being similar to the flat moving surface, both which are referred to as the moving surface  14 . In CP DB , the blade holder  24 ,  44  is oriented so that the Blade Holder Angle (BHA)&lt;90 degrees as defined from the downstream side of the cleaning tip  30 ,  50 . BHA can be measured as the angle between T ND  and T B , where T ND  extends along the undeflected downstream side of the blade member  22   b ,  42   b  (i.e., just as it extends from the rigid blade holder  24 ,  44 ) and T B  is a tangent to the downstream side of the blade member taken at the cleaning tip  30  or  50  when in cleaning contact with the moving surface. 
   In CP DB , the cleaning blade  20  or  40  has been moved against the moving surface  14  with a predetermined pressure applied to the blade holder  24  or  44  to keep the tip  30  or  50  in cleaning contact against the moving surface  14  as the photoreceptor  12   a  or  12   b  moves in its operational direction  15 . The compliant blade member  22  or  42  is deflected by a predetermined Blade Deflection Angle (BDA), which can be measured between T B  and T ND . In CP DB , the blade member  20 ,  40  forms a working angle WA measured at the downstream side of the cleaning tip  30 ,  50  between T B  and T PR . In the example provided, BDA=BHA−WA. The WA can range from about 4 degrees to about 12 degrees, with other suitable ranges including from about 8 degrees to about 12 degrees. The BDA range BDA is chosen to provide a desired blade load for the chosen blade material. The modulus of the blade material, the blade thickness, the amount of extension of the blade member  22 ,  42  from the blade holder  24 ,  44  and the friction against the moving surface  14  determine the blade deflection, as measured by the BDA, required to obtain the desired blade load. The BHA is chosen to obtain both the desired BDA and WA. The blade loads can range from about 15 g/cm to about 60 g/cm with other suitable ranges including from about 25 g/cm to about 35 g/cm. Referring now to  FIG. 4  the Doctor Blade orientation for cleaning blades  20 ,  40  disposed in CP DB  for a flexible moving surface  14 , such as for example a flexible photoreceptor  12   c , is shown generally at  400 . BDA is measured in a similar manner as described above, as the angle between T B  and T ND . BHA is measured as the angle between T ND  and T B . WA is the angle between T B  and T PR . 
   The cleaning system  16  moves both cleaning blades  20  and  40  into the same CP DB  at the same location in a mutually exclusive manner so only one blade occupies the location at a time, so as to form the same BHA, BDA and WA for both cleaning blades. This is applicable for the moving surfaces  14  described above. 
   Referring now to  FIGS. 5 and 6 , an example of the image forming device, shown generally at  10 ′, having a cleaning system with a Wiper Blade arrangement is shown generally at  16 ′. The Wiper Blade cleaning system  16 ′ is similar to the Doctor Blade cleaning system  16  described above, with similar components referenced by like reference numerals using a (′) to indicate the Wiper Blade distinction. As such, the cleaning system  16 ′ includes first  60 ′ and second links  70 ′ disposed at each opposite lateral end of the cleaning blades  20 ′ and  40 ′, and connected thereto at first  62 ′,  72 ′ and second  64 ′,  74 ′ pivot connections similar to those described above. One or more actuators  94 ′,  95 ′, similar to those described above, are connected to at least one of the first or second links for rotating them about the third pivot connections  66 ′,  76 ′ thereby moving the cleaning blades between a single common Cleaning Position CP WB  and two separate, respective Suspended Positions. 
   In  FIG. 5 , the first cleaning blade  20 ′ is in CP WB  such that the first blade member cleaning tip  30 ′ is in cleaning contact with the moving surface  14 ′ in the Wiper Blade orientation. The second cleaning blade  40 ′ is in its respective Suspended Position such that the cleaning tip  50 ′ is separated from the moving surface  14 ′ as shown. At the end of the useful operational life of the first cleaning blade  20 ′, the actuator  94 ′ moves the drive link  60 ′ rotating it about the third pivot connection at an axis similar to axis A described above, thereby rotating the follower link about its corresponding third link at an axis similar to axis B described above, also, to move the first cleaning blade  20 ′ from CP WB  to its respective Suspended Position as shown in  FIG. 6 . The second cleaning blade  40 ′ is simultaneously moved from its Suspended Position into the CP WB  at the same location previously occupied by the first blade  20 ′, such that the second blade member cleaning tip  50 ′ is in cleaning contact with the moving surface  14 ′ in the Wiper Blade orientation. 
   Referring now to  FIG. 7  the Wiper Blade orientation for cleaning blades  20 ′ and  40 ′ disposed in CP WB  for a curved moving surface  14 ′, such as a drum photoreceptor  12   a ′, and a flat moving surface  14 ′, such as a flat rigid photoreceptor  12   b ′, is shown generally at  700 . Tangents T PR , T B , and T ND  are similar to those described above are used. In CP WB , the blade holder  24 ′,  44 ′ is oriented so that BHA&lt;90 degrees as defined from the upstream side of the cleaning tip  30 ′,  50 ′. BHA can be measured as the angle between T ND  and T PR  as shown. 
   In CP WB , the cleaning blade  20 ′ or  40 ′ has been moved against the moving surface  14 ′ with a predetermined pressure applied to the blade holder  24 ′ or  44 ′ to keep the tip  30 ′ or  50 ′ in cleaning contact against the moving surface  14 ′ as it moves in the operational direction  15 ′. The compliant blade member  22 ′ or  42 ′ is deflected by a predetermined BDA, which can be measured between T B  and T ND . In CP WB , the blade member  20 ′,  40 ′ forms a working angle WA measured at the downstream side of the cleaning tip  30 ′,  50 ′ between a tangent to the end of the blade member T E  and T PR  as shown. In the example provided, BDA=BHA−WA. Similar ranges to those described above are suitable. 
   Referring now to  FIG. 8  the Wiper Blade orientation for cleaning blades  20 ′,  40 ′ disposed in CP WB  for a flexible photoreceptor  12   c ′ having a flexible moving surface  14 ′ is shown generally at  800 . BDA is measured in a similar manner as described above, as the angle between T B  and T ND . BHA is measured as the angle between T ND  and T B . WA is the angle between T E  and T PR . 
   The cleaning system  16 ′ moves both cleaning blades  20 ′ and  40 ′ into the same CP WB  at the same location in a mutually exclusive manner so only one blade occupies the location at a time, so as to form the same BHA, BDA and WA for both cleaning blades. This is applicable for the moving surfaces  14 ′ described above. 
   The cleaning system  16  ( 16 ′) uses first and second three-pivot links  60 ,  70  ( 60 ′,  70 ′) to couple the first and second cleaning blades  20 ,  40  ( 20 ′,  40 ′) together to provide accurate and repeatable positioning of both cleaning blades  20 ,  40  ( 20 ′,  40 ′) into a single Cleaning Position CP DB  (CP WB ). The cleaning blade not occupying the Cleaning Position is moved into one of two respective Suspended Positions. The cleaning system  16  ( 16 ′) provides a compact dual blade arrangement which can effectively double the useful life of the cleaning system as compared to single blade cleaners. 
   The cleaning system  16  ( 16 ′) is configured to allow simplified replacement of blades  22 ,  42  ( 22 ′,  42 ′). As the end of life of an operating cleaning blade is reached, the used blade  22  ( 22 ′) or  42  ( 42 ′) is withdrawn from contact with the moving surface  14  ( 14 ′) and the second blade is placed into operation in the Cleaning Position. The life of the cleaning system  16  ( 16 ′) between service intervals required for replacement of used blades is therefore extended with high reliability to more than twice the life of a conventional single blade system. 
   Blade changes can be initiated base on accumulated blade use, or blade failure identified by a failure sensor or the customer. Failure sensors can detect cleaning failures on the photoreceptor before they appear on prints, leading to blade replacements before customers are aware of faults. 
   If the cleaning system  16  ( 16 ′) is contained within an XRU  17 , the system can be easily replaced by replacing the XRU. The two blade cleaning system life would therefore be matched to the expected life of the other XRU components. For example, if a conventional XRU  17  having a single blade system has a cleaning blade life that is slightly longer than the life of the photoreceptor  12 , then when a long life overcoat is applied to the photoreceptor to double its life, the blade life will become inadequate. A doubling of the expected useful life of the cleaning blade would typically more than triple the number of cleaning blade failures. Thus, the cleaning blade would then become the life limiter for the XRU. Changing from a conventional single blade to the two blade cleaning system  16  ( 16 ′) will enable a long life XRU more suitable for use with the overcoated photoreceptor. 
   If the cleaning system  16  ( 16 ′) is directly mounted into the machine bases  67 , replacement can be independent of the other xerographic elements. When both blades  20 ,  40  ( 20 ′,  40 ′) have been used, the cleaning system can be replaced as a single unit. Alternatively, new cleaning blades  20 ,  40  ( 20 ′  40 ′) can be mounted to the links  60 ,  70  ( 60 ′,  70 ′). To avoid spreading dirt while changing cleaning blades, it is preferred to replace the cleaning system as a single unit. The single unit could, however, be reused by cleaning and replacing the blades in a remanufacturing process if so desired. 
   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.