Patent Publication Number: US-8112027-B2

Title: Image forming machine blade engagement apparatus with blade cassette

Description:
BACKGROUND 
     Disclosed in embodiments herein are apparatuses for cleaning and/or applying release agent to an image forming machine moving surface, such as a photoreceptor, transfer surface, etc., and more specifically a blade engagement apparatus having a blade cassette holding a plurality of blades for individual withdrawal and placement into a working position in engagement with the moving surface for cleaning and/or metering. 
     In electrophotographic applications such as xerography, a charge retentive moving photoreceptor belt, plate, 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 the moving photoreceptor surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. 
     The electrostatic image on the moving 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. Once each toner image is transferred to a substrate, the image is affixed thereto forming 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 moving photoreceptor surface. 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”) that may remain on the charged moving surface of the photoreceptor must be removed. 
     Solid ink jet image forming machines generally use an electronic form of an image to distribute ink melted from a solid ink stick or pellet in a manner that reproduces the electronic image. In some solid ink jet imaging systems, the electronic image may be used to control the ejection of ink directly onto a media sheet. In other solid ink jet imaging systems, the electronic image is used to eject ink onto an intermediate imaging member. A media sheet is then brought into contact with the intermediate imaging member in a nip formed between the intermediate member and a transfer roller. The heat and pressure in the nip helps transfer the ink image from the intermediate imaging member to the media sheet. 
     One issue arising from the transfer of an ink image from an intermediate imaging member to a media sheet is the transfer of some ink to other machine components. For example, ink may be transferred from the intermediate imaging member to a transfer roller when a media sheet is not correctly registered with the image being transferred to the media sheet. The pressure and heat in the nip may cause a portion of the ink to adhere to the transfer roller, at least temporarily. The ink on the transfer roller may eventually adhere to the back side of a subsequent media sheet. If duplex printing operations are being performed, the quality of the image on the back side is degraded by the ink that is an artifact from a previous processed image. 
     To address these problems, various release agent applicators have been designed, often as part of an image drum maintenance system. These release agent applicators provide a coating of a release agent, such as silicone oil, onto the intermediate imaging member moving surface to reduce the undesired build-up of ink. It is desired to control the amount of release agent applied, since using of too much release agent causes undesirable streaks, also known as oil streaks, on the output prints. 
     The present application provides a new and improved apparatus for cleaning and/or metering a release agent onto an image forming device moving surface which overcomes these above-described problems. 
     BRIEF DESCRIPTION 
     A blade engagement system for cleaning and/or metering a release agent onto an image forming machine moving surface is provided. 
     In one exemplary embodiment, the blade engagement system includes a blade cassette including a plurality of blades, and a blade engagement apparatus having a cassette chamber adapted for removably receiving the blade cassette and a blade positioning mechanism moving the blades, one at a time, from the blade cassette to a working position in engagement with the image forming machine moving surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is partial sectional side view of a blade cassette of section A-A in  FIG. 2A  being inserted into a blade engagement apparatus; 
         FIG. 2A  is a top view of a new blade cassette with its top removed for clarity having four blades stored in a new blade storage area; 
         FIG. 2B  is sectional view along B-B of the cassette shown in  FIG. 2A ; 
         FIG. 3A  is a front view of an arm assembly; 
         FIG. 3B  is a side view of an arm assembly gripping a partially shown blade; 
         FIG. 3C  is a back view of an arm assembly; 
         FIG. 3D  is a sectional view of the arm assembly without a blade along D-D of  FIG. 3B ; 
         FIGS. 4A-4B  illustrate a portion of a cassette and a portion of an arm assembly gripping a blade and moving it into a working position; 
         FIG. 5  is a side sectional view of the blade engagement apparatus showing a first blade moved into the working position; 
         FIG. 6A  is a side view of an arm assembly received in an exemplary blade guide and gripping a blade, only a portion of which is shown; 
         FIG. 6B  is a front view of the arm assembly received in the blade guide shown in  FIG. 6A ; 
         FIG. 6C  is a front view of the arm assembly received in another embodiment of blade guide; 
         FIG. 7A  is a side view of an arm assembly gripping blade, only a portion of which is shown, and the blade is received in another embodiment of a blade guide; 
         FIG. 7B  is a front view of the arm assembly gripping a blade which is received in the blade guide shown in  FIG. 7A ; 
         FIG. 7C  is a front view of an arm assembly gripping a blade which is received in another embodiment of a blade guide; 
         FIG. 8  is a top view of a blade cassette with top removed for clarity in a blade engagement apparatus with top removed to show the arm assemblies illustrating a spring biased blade conveyor; 
         FIGS. 9A-9D  illustrate a portion of a cassette and a portion of an arm assembly moving a used blade from a working position back into the cassette for storage; 
         FIG. 10  is a top view of a blade cassette with top removed for clarity in a blade engagement apparatus with top removed to show the arm assemblies illustrating a power operated blade conveyor; and 
         FIG. 11  is a sectional side view of a portion of the blade engagement apparatus and cassette shown in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , an image forming machine such as a xerographic copier, printer, multifunction machine, and the like, shown generally at  10 , includes a moving surface  12  moving in an operational direction  13 . The moving surface  12  can be suitable for receiving a controlled application of a release agent, or a surface suitable for cleaning, such as the removal of toner waste material etc., or both. The moving surface  12  can be a cylindrical surface such as a solid ink jet (SIJ) drum used in SIJ machines  10 . In other examples, the cylindrical surface  12  can be an imaging member, such as a photoreceptor, or a glossing drum, or a transfer surface, or other like surfaces. 
     The image forming machine  10  includes a blade engagement system  102  including blade engagement apparatus  100  adapted to receive a removable blade cassette  150  containing a plurality of blades  152   1 - 152   n  used for cleaning and/or applying a release agent to the image forming machine moving surface  12 . 
     For the purposes of example, the blade cassette  150  is shown to contain four blades  152   1 - 152   4 , however it should be appreciated that the cassette can house more than four blades. The blade engagement apparatus  100  includes a blade positioning mechanism  110  for moving one of the blades  152   1 - 152   4  from the cassette into a working position, also referred to as an operational position, in controlled engagement with surface  12 , as shown in  FIG. 5  and described in further detail below. The blade engagement apparatus  100  (and system  102 ) can be controlled by a controller  104 . 
     The blade engagement apparatus  100  (and system  102 ) can be a release agent application apparatus (and system) for applying a controlled amount (i.e. thickness) of release agent  11  onto the surface  12 , in a process referred to herein as metering. During metering, the release agent  11  is initially applied to the surface  12  using a roller  14 , or in other known manners, and then metered to a desired thickness by a blade disposed in a working position. The blade engagement apparatus  100  (and system  102 ) can be a cleaning apparatus (and system) for cleaning debris from the moving surface  12  with the blade disposed in the working position. The blade engagement apparatus  100  (and system  102 ) can be configured for cleaning, or metering, or both simultaneously. 
     After a blade has reached the end of its operational life, the blade positioning mechanism  110  moves the used blade from the working position into the blade cassette  150  for storage and moves another, unused blade into the working position in a manner described below. This process can be repeated until all the blades have been used, at which time the blade cassette  150  can be removed from the blade engagement mechanism  100  and a new one inserted in its place. 
     Referring now to  FIGS. 1 ,  2 A and  2 B, the blade engagement apparatus  100  includes a housing  112  having a cassette chamber  114 . The housing  112  includes an opening communicating with the chamber  114  forming a cassette receptacle  116 . 
     The blade engagement apparatus  100  also includes a pair of spaced apart walls  118   a  &amp;  118   b  forming a chute  120  communicating with the chamber  114  and extending downwards therefrom. The chute  120  includes an opening forming a blade window  122  disposed adjacent to the surface  12 . The blade window  122  extends laterally across the width of the surface  12  to be engaged by the blade while in the operational position as described in further detail below. 
     A blade cassette  150  having a plurality of blades  152   1 - 152   n  is slid through the blade receptacle  116  and into the cassette chamber  114 . The cassette  150  has a cassette housing  160  having a top  161 , a bottom  162  sides  163 , a first end  164 , and a second end  16  disposed opposite the first end. The cassette includes a first internal portion  166 , referred to as the unused blade storage section of the cassette, for storing unused blades, as shown in  FIG. 1 , and a second internal portion  167 , referred to as the used blade storage section of the cassette, for storing used blades. 
     The cassette  150  includes a first pair of protrusions, each extending from the interior of the side walls  163  forming a pair of first rails  168  extending along the side walls for the length of the unused blade storage section  166  from the second end  165  to a mid portion of the cassette. The first rails  168  include flat upper surfaces  168   a  which are laterally aligned forming surfaces for supporting unused blades stored in the unused blade section of the cassette as described below. 
     The cassette  150  also includes a second pair of protrusions, each extending from the interior of the side walls  163  forming a pair of second rails  169  extending along the side walls for the length of the used blade storage section  167  from the first end  164  to a mid portion of the cassette. The second rails  169  include flat upper surfaces  169   a  which are laterally aligned forming surfaces for supporting used blades stored in the used blade section of the cassette as described below. 
     The cassette  150  also includes a laterally extending aperture  170  disposed in a mid portion of the cassette bottom  162  between the new blade storage section  166  and the used blade storage section  167 , referred to as the loading/unloading aperture. The blades  152  are ejected from the cassette  150  through the loading/unloading aperture  170  and moved into the working position for use. One blade can occupy the working position at a time. At the end of a blade&#39;s operational life, it is placed back into the cassette through the loading/unloading aperture  170  and stored in the used blade section  167  while the next blade is moved from the cassette and placed into operation in the working position. 
     It should be appreciated that the blades  152   1 - 152   n  are similar and shall be referred to generally as blade  152 . As shown in  FIG. 2B , each blade  152  includes a blade holder  202  formed of a rigid material such as for example, aluminum, steel, a composite, or other suitably rigid material. The blade holder  202  includes an elongated body  203  having a length sufficient for extending transversely across surface  12 , with respect to the operational direction  13 , when the blade  152  is placed in the working position. The blade holder body  203  includes a top  204  having a flange  206  extending at an approximate  90  degree angle from the body along the length of the blade holder for added rigidity. The blade holder body  203  also includes a bottom  208 . 
     The rigid blade holder  202  is connected to, or integrated with, a compliant blade member  210  to evenly distribute the application forces applied to the blade  152  by the blade positioning mechanism  110 . The blade member  210  extends from the bottom  208  of the blade holder  202  and includes a blade tip or edge  211  extending along most of the length of the holder. The blade member  210  is formed of a compliant material, such as polyurethane, which bends, or deflects, as the blade  152  is moved into the working position in which the blade tip  211  is pressed against, or towards, surface  12  generating a blade load at the tip against the surface, or material on the surface such as a release agent being metered. The tip  211  can be coated with PMMA, SureLube, toner or other initial blade lubricant to prevent blade flip as the blade  152  is moved into the working position, if so desired. 
     The blade holder body  203  also includes oppositely disposed lateral ends  212 . A recess  214  is formed in the body  203  at each end  212  beneath the flange  206  defining a tang  215  extending from each end of the body below the recess. The blade member  210  extends along the blade holder bottom between the tangs  215 . The ends of the flange  206  extending laterally outwards over the recess  214  form laterally extending tabs  216 . In the unused blade storage section  166  of the cassette  150 , the rails  168  extend into the recesses  214  supporting unused blades  152  in a sequential line of individual/unattached blades, each blade oriented in a similar manner with its tabs supported on the upper rail surfaces  168   a . In the used blade storage section  167 , rails  169  extend into the recesses  214  of the used blades  152  supporting the used blades for sliding movement as blades are moved back into the cassette through the loading/unloading aperture  170  for storage. 
     The cassette  150  includes a blade conveyor assembly  190 , shown in  FIGS. 2A and 2B , for moving the blades  152  sequentially from the new blade storage section  166  to the loading/unloading aperture  170  for use, and then to the used blade storage section  167  for storage after use. In the first exemplary embodiment, shown in  FIGS. 1-9D , the blade conveyor assembly  190  is spring biased by spring  182 . 
     The blade conveyor assembly  190  includes a plurality of laterally extending conveyer bars  192  having ends  193  supported on the rails  168 ,  169 . The blade conveyor assembly  190  also includes a pair of spaced apart link members  194  extending at right angles to the bars  192  connecting the bars together in a spaced apart manner such that one bar is disposed between each blade  152 . A different bar  192  abuts the blade holder flange  206  behind each blade  152   1 - 152   n  for moving that blade in a direction towards the loading/unloading aperture  170 . 
     The connector members  194  can extend into parallel recessed channels  195  formed in the interior of the top  161  of the cassette housing  160  which enable the blade conveyor assembly  190  to track straight and stay square as it moves the blades towards the loading/unloading aperture for use. The connector members  194  can also extend down, between each blade  152 , so that each rests against an inner side of the rails  168  enabling the blade conveyor assembly to track straight and stay square, keeping the blades parallel, and preventing them from skewing and binding as they slide along the rails  168 . 
     The blade conveyor assembly  190  also includes an end plug  180  extending behind the sequentially last blade  152   n  which is spring biased towards the loading/unloading aperture  170  by a compression spring  182 . The spring biased blade conveyor assembly  190  urges the blades  152  towards the loading/unloading aperture  170  as their tabs slide over the rail upper surfaces  168   a . A pin  184  extending through each cassette side wall  163  is used to prevent the unused blades from reaching the aperture  170  while the cassette is not in place in the cassette chamber  114 . 
     Referring now to  FIGS. 1 ,  3 A- 3 D and  5 , the blade positioning mechanism  110  includes a pair of arm assemblies  300 , one disposed at each lateral side of the blade engagement apparatus  100 . The arm assemblies  300  are located in housings  124  extending from the top of the blade engagement housing  112  directly above the chute  120  for moving a blade  152  from the blade cassette  150  into an operational position in engagement with the surface  12  and subsequently returning it to the cassette as shall be described in further detail below. 
     The arm assemblies  300  are similar and therefore, one shall be described in detail. The arm assembly  300  includes an arm  302  having a rack  303  disposed on a first side for cooperating with a sprocket  362  turned by a powered actuator, such as motor  360  shown in  FIGS. 5 and 8 , for moving the arm  302  up and down. The motor  360  can be a stepper motor, or other motor, controlled for bidirectional actuation by a controller  104 . The controller  104  can be in the image forming machine  10 , or in the blade engagement apparatus  100 , and electrically connected to the motor  360  for controlling its actuation A second arm  304  is coupled to the first arm  302  for sliding, up and down movement relative to the first arm, and also for mutual up and down movement together with the first arm via actuating movement by motor  360  as described in further detail below. In another exemplary embodiment, the arms  302  and  304  can be moved up and down with a screw  352  turned by an actuator such as a motor cooperating with a threaded member  350  on the first arm, shown with dotted lines to indicate an alternate embodiment. 
     The first arm  302  includes an upper clamp jaw  306  having an upper surface  307   a  and a lower surface  307   b . The upper clamp jaw  306  can also include downwards facing recess  308  in the lower surface  307   b . The second arm  304  includes a lower clamp jaw  310  which can include an upwards facing recess  312  aligned with recess  308 . The upper and lower clamp jaws  306  and  310  are arranged in a facing relationship with each other. The second arm  304  is spring biased upwards with respect to the first arm  302  by spring  318  to bias the lower clamp jaw  310  in a direction towards the upper clamp jaw  306  to clamp the blade end  212  between the jaws. The clamp jaws  306 ,  310  of one arm assembly  300  are arranged in a facing relationship with the jaws the other arm assembly for gripping both ends  212  of the blade holder. In one exemplary embodiment, the jaws  306 ,  310  can clamp the blade tangs  215  in recesses  308  and  312 , as shown in  FIG. 3B . 
     The second arm  304  includes a projection  314  extending from a side of the arm assembly  300  opposite jaw  310 . A stop  330  disposed in the blade engagement apparatus  100  is used to abut the projection  314  preventing movement of the second arm  304 , and its lower jaw  310 , while the first arm  302  is moved by motor  360  to move the upper jaw relative to the lower jaw for clamping and unclamping the blades  152 , as described in further detail below. The stop  330  can be moved away from the projection  314 , along a pivot axis  332  or by translating it laterally, such as by using a solenoid  334  connected to the stop. Moving the stop  330  away from projection  314  a sufficient distance to avoid this abutment enables the jaws  306  and  310  to be moved together such as when the arms are withdrawn into the arm housings  124 . Alternatively, the first arm can include a projection  320  extending from a side opposite the upper jaw  306  having an upper beveled edge  322  and a lower beveled edge  324  which moves the stop away from the second arm projection  314  on its pivot axis  322  as the first arm is moved. 
     Referring now to  FIGS. 1 ,  4 A,  4 B and  5 , the operation of the blade engagement apparatus  100  shall be described. To place a blade cassette  150  into the blade engagement apparatus  100 , the arm assemblies are withdrawn, or retracted, upwards and into the housings  124  such that the jaws are moved up and out of the cassette chamber  114 . The new blade cassette  150  is pushed into the blade receptacle  116  so that the cassette is received into the chamber  114  and the loading/unloading aperture  170  is aligned with the chute  120 . The new cassette  150  includes a plurality of new, unused blades disposed in the unused blade section  166  and biased towards the loading/unloading aperture  170  by the guide assembly  190  as described above. 
     After the cassette  150  is in place in the chamber  114 , the arm assemblies  300  are lowered with motor  360  moving each of the first and second arms  302  and  304  downwards together. The stop  330  is moved away from the second arm projection  314  using solenoid  334 , or it is pushed away by projection  320  on the first arm as it passes by, allowing the second arm projection to reach a position below and adjacent the stop  330  as shown in  FIG. 3B . A sensor  340  sensing the location of the second arm projection  314  adjacent stop  330  can be used to determine that the second arm  304  and the lower jaw  310  are in position for gripping a blade  152 . 
     The motor  360  is then reversed, raising first arms  302  relative to second arms  304 , which are prevented from being raised by stop  330 , thereby opening the jaws  306  and  310  to accept the first blade  152   1 , as shown in  FIG. 4A . The pins  184  are retracted allowing the first blade to be moved along rails  168  by the blade conveyor assembly  190  until the blade holder tabs  216  of flange  206  abut stops  169   a  on the second rails  169  (shown by the star in  FIG. 4A ) and the first blade  152   1  is positioned over the loading/unloading aperture  170 . 
     The motor  360  is reversed again lowering the first arms  302  while the second arms  304  remain stationary due to the spring bias provided by springs  318 . Lowering the first arms  302  moves the upper clamp jaws  306  downwards clamping the tangs  215  in the facing recesses  308  and  312  of the respective jaws  306  and  310 , as shown by the stars in  FIG. 4B . It can be determined that a blade is clamped by the jaws  306 ,  310  by sensing the second arm projection  314  is adjacent stop  330  via sensor  340  and determining the relative positions of the jaws by monitoring the first arm position such as by monitoring the actuation of the motor  360 . A higher first arm position can indicate a blade  152  is clamped by jaws  306  and  310 , whereas a lower first arm position can indicate a blade is not present. 
     As shown in  FIG. 5 , the arm assemblies  300  are lowered further, and the second arms  304  travel with the first arms  302  moving the first blade  152   1  down the chute  120  until the blade reaches the working position. At the working position, the blade member  210  extends through the blade window  122  and the blade tip  211  is pressed against, or towards, surface  12  with a predetermined application force to generate a desired blade load at the blade tip  211  towards surface  12  for metering, or cleaning, or both. 
     The blade engagement apparatus  100  can include blade guides for locating a blade  152  with respect to surface  12  when placing the blade into the working position. In some exemplary embodiments, the blade guides can include one or more surfaces cooperating with the arms as they move a blade into the working position. Referring to  FIGS. 6A and 6B  a blade guide  600  includes a first surface  602  spaced apart from a second surface  604 . The surfaces  602  and  604  can be parallel or include parallel portions. The surfaces  602  and  604  can be the surfaces of spaced apart plates  603  and  605 , or portions  606  of the blade engagement apparatus  100  disposed adjacent the arm assemblies  300  for receiving the arms  302 ,  304  therebetween as they move the blade  152  into the working position. The surfaces  602  and  604  can stabilize the orientation of the blade  152  with respect to the surface  12  as the blade enters the working position, reducing chatter. The surfaces  602  and  604  can include flared portions,  602   a  and  604   a  respectively, providing a wider opening for receiving the arm assemblies  300 . 
     The surfaces  602  and  604  are oriented with respect to moving surface  12  to set and maintain a consistent, predetermined blade angle for each blade  152  as it is placed into the working position. Controlling the positioning of the arms  302  and  304  controls the positioning of the jaws  306  and  308  clamping the blade holders  202  which controls the position of the blade member with respect to the surface  12 . 
     The guide  600  can include an end surface  608  providing a stop for the arm assemblies  300  moving towards the surface  12 . Moving the arm assemblies  300  against the stop produces a predetermined blade load at the blade tip  211  which can be repeated for each of the similarly shaped blades  152 . 
     Referring to  FIG. 6C , in another exemplary embodiment, the guide  620  can include a spring biased member  622  having a surface  624  biased towards surface  604  for receiving the arm assemblies  300  therebetween and pressing the arm assemblies against surface  604  providing similar control over blade positioning and blade load as the guide  600 . 
     In other exemplary embodiments, the blade guide can include one or more surfaces cooperating with the blade  152  as it is moved into the working position. Referring to  FIGS. 7A and 7B , a blade guide  700  can include a first surface  702  spaced apart from a second surface  704  for receiving the blade holder end  212  therebetween providing similar control over blade positioning and blade load as the guide  600 . The surfaces  702  and  704  can be the surfaces of spaced apart plates  703  and  705 , or portions  706  of the blade engagement apparatus  100  disposed adjacent the arm assemblies  300  for receiving the arms  302 ,  304  therebetween as they move the blade  152  into the working position. The surfaces  702  and  704  can include flared portions,  702   a  and  704   a  respectively, providing a wider opening for receiving the blade holder  202  as the blade is moved into the working position. 
     The guide  700  can include an end surface  708  providing a stop for the blade  152  as the arm assembly  300  moves it towards the surface  12 , producing a predetermined blade load for each blade as described above. 
     Referring to  FIG. 7C , in another exemplary embodiment, the guide  720  can include a spring biased member  722  having a surface  724  biased towards surface  704  for receiving the arm assemblies  300  therebetween and pressing the arm assemblies against surface  704 , such as the surface of plate  705 , providing similar control over blade positioning and blade load as the guide  600 . The spring biased member  722  can be a ball, an arm or other structure biased towards surface  704 . 
     The blade load can be increased while the blade  152  is in the working position by the motor  360  moving the arm assemblies downwards thereby moving the blade holder  202  in a direction towards the surface  12 , increasing the deflection of the compliant blade member  210  which can also be referred to as increasing the interference of the blade  152 . Increasing the blade load can meter a thinner layer of release agent  11  onto the surface during a metering operation, or clean more debris from the surface during a cleaning operation, or both. The blade load at tip  211  can be decreased while the blade  152  is in the working position, to meter a thicker layer of release agent and/or remove less debris from surface  12 , by the actuator  360  moving the arm assemblies upwards thereby moving the blade holder  202  in a direction away the surface  12  while the blade tip  211  remains in contact with the surface. 
     Sensors can be used to monitor for streaks on output prints or on moving surface  12  and motor  360 , controlled by controller  104 , can provide incremental bi-directional changes in rotation to arm assemblies  300  moving the blade  152  towards or away from surface  12  to make small changes in the blade load to achieve a minimum blade load needed for preventing streaks during image forming, as described in further detail in the co-pending application U.S. application Ser. No. 12/201,140 filed Aug. 29, 2008, entitled “SYSTEM AND METHOD OF ADJUSTING BLADE LOADS FOR BLADES ENGAGING IMAGE FORMING MACHINE MOVING SURFACES”, the disclosure of which is hereby incorporated by reference in its entirety. 
     It is contemplated that two motor actuators  360 , one for each arm assembly  300 , can be used and controlled separately, if so desired. Using two motor actuators  360 , the blade  152  can be skewed in the chute  120 , such that the blade holder  210  is not parallel with respect to the surface  12 , by moving the arm assemblies  300  such that each of the associated jaws are disposed a different distance from the surface. In this manner, it is possible to vary the blade interference, and thus the blade load, differently at each end of the blade  152 . 
     At the end of the operational life of a blade  152 , the used blade is withdrawn from operation by moving it from the working position back into the blade cassette for storage in the used blade section  167 . Referring to  FIGS. 8 , and  9 A- 9 D, a used blade  152   2  which is the second sequential blade in the blade cassette, is shown being moved up the chute  120  and into the used blade section  167  behind the first sequential used blade  152   1 . 
     The arm assemblies  302  are moved upwards via actuator  360  as shown in  FIG. 9A  until the second arm projections  314  abut stops  330 . The first arms  302  are raised further moving the upper jaw  306  upwards to unclamp the tangs  215  as shown in  FIG. 9B . The first arm  302  is raised still further lifting the blade tabs above the stop  169   a  and above the biased conveyor bar  192  enabling the bar to move into abutment with the blade holder body  203  beneath the flange  206 , as shown by the star in  FIG. 9C . As the blade holder tab  216  is moved above the stops  169   a  the biased conveyer bar  192  moves along the used blade rails  169  moving the used blade into the used blade section  167  of the cassette  150 . The first arm  302  is then lowered to move the upper jaw below the sequentially next unused blade which is then clamped and moved down the chute into the working position in a manner as described above. 
     Referring now to  FIGS. 10 and 11 , in another exemplary embodiment, the cassette, shown generally at  900 , includes a power operated blade conveyor assembly  920  moved by an actuator motor  936 . The conveyor assembly  920  includes a pair of spaced apart racks  922 , one disposed at each lateral side of the blade cassette on top of the blade holder flanges  206 . The racks  922  extend parallel to each other and perpendicular to the direction of movement of the blades along rails  168  and  169 . The conveyor assembly  920  also includes a plurality of spacer members  924  extending downwards from the racks  922  such that one spacer member is disposed behind the blade holder flange  206  of each blade  152 . The racks  922  can be connected to each end of a member  930  extending parallel to the blades  152  keeping the parallel racks connected together in the spaced apart relationship. 
     A main shaft  944  extends from a powered actuator, such as motor  936 , to a pair of spaced apart sprockets  340  disposed above the unused blade storage section, each meshed with one of the racks  922  for moving the racks in a direction towards the loading/unloading aperture  170  as the motor  936  rotates. A second pair of sprockets  962  are disposed above the used blade storage section  167  and mesh with the racks  922  for moving the used blades from the loading/unloading aperture into the used blade storage section. The second sprockets  962  are disposed on an idler tube  956  mounted on the arm shaft  364 . The idler tube  956  is coupled to the main shaft  944  for mutual rotation using a belt assembly  950  including a belt  960  connecting a sprocket  946  on the main shaft to a sprocket  952  on the idler shaft. In this manner, a single motor  936  can drive both racks  922  for moving the blades  152  from the unused blade storage section to the loading/unloading window and on to the used blade storage section. 
     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.