Patent Publication Number: US-7221889-B2

Title: Replaceable developer roller

Description:
BACKGROUND 
   The present disclosure relates generally to developer rollers and more particularly to replaceable developer rollers. 
   A binary ink developer (BID) is a consumable that is often used in a printing device. This consumable is generally made from custom and/or off-the-shelf parts. Failure of a component(s) in this consumable may, in some instances, induce an operator to replace the entire BID. This is due, at least in part, to the relative difficulty of replacing the components within the BID. 
   One component of the BID is the developer roller. Current developer rollers include a solid aluminum shaft with a urethane layer molded thereon. Generally, the life span of a developer roller may be variable. Potential failures associated with the developer roller may, in some instances, affect the print quality of the BID. As such, operators may be inclined to replace the developer roller itself, however, this is generally not an easy task. The replacement of the developer roller in current binary ink developers includes the potential risk of damaging another component during replacement. Further, as many components generally need to be removed in order to get the developer roller out of the BID, the process would generally be time consuming. Still further, special tools and/or training would likely be used in the process, as there are generally several fasteners that are assembled to a specific torque. 
   As such, it would be desirable to provide a developer roller that is relatively easily removable from a binary ink developer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Objects, features and advantages will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though not necessarily identical components. For the sake of brevity, reference numerals having a previously described function may not necessarily be described in connection with subsequent drawings in which they appear. 
       FIG. 1  is a cross sectional semi-schematic view of an embodiment of a binary ink developer; 
       FIG. 2  is an exploded side view of an embodiment of a replaceable developer roller apparatus; 
       FIG. 3  is a cutaway perspective view of an embodiment of a hollow cylindrical developer roller; 
       FIG. 4  is an exploded perspective view of an embodiment of a splined drive assembly shaft and a complementarily splined frusto-conical drive member; 
       FIG. 5  is a flow diagram depicting an embodiment of the method of replacing an embodiment of a developer roller; 
       FIG. 6  is an exploded side view of an alternate embodiment of a replaceable developer roller apparatus; and 
       FIG. 7  is a flow diagram depicting an alternate embodiment of the method of replacing an embodiment of a developer roller. 
   

   DETAILED DESCRIPTION 
   Liquid electro photography (LEP) printers generally operate in a manner similar to dry electro photography printers, or laser printers. Like a laser printer, a photoconductive drum is charged and is then selectively exposed to a laser to form a charge pattern that corresponds to an image. In LEP printers, the drum is then contacted with a binary ink developer (BID) that selectively transfers a liquid ink pattern to the charge pattern. The liquid ink pattern is transferred from the photoconductive drum to a medium to form the image on the medium. 
   Referring now to  FIG. 1 , an embodiment of a printing device  1000  (shown in phantom) having a BID  100  therein is depicted. Generally, the BID  100  includes a developer roller  12 , a main electrode  114 , a squeegee roller  116 , a cleaning roller  118 , a wiper  120 , a sponge roller  122 , a squeezer roller  124 , and an ink tray  126 . 
   A potential bias between the main electrode  114  and the developer roller  12  initially transfers charge to the developer roller  12 . The squeegee roller  116  regulates the ink film thickness on the developer roller  12 . Ink is then selectively transferred from the developer roller  12  to charged portions of the photoconductive drum surface (not shown). The cleaning roller  118  substantially removes remaining ink from the developer roller  12 , the wiper  120  cleans the cleaning roller  118 , and the sponge roller  122  cleans the wiper  120 . This cleaning process, in many instances, may substantially minimize sludge buildup. 
   The embodiment of the BID  100  shown in  FIG. 1  may, in some instances, have a relatively limited life, due, at least in part, to wear of its internal parts over time, the relatively limited life of its developer roller  12 , and potential sludge buildup inside the BID  100 . 
   Embodiment(s) of the present disclosure provide a replaceable developer roller apparatus that is suitable for use in a BID  100  (such as that shown in  FIG. 1 ) in a printing device  1000 . Without being bound to any theory, it is believed that embodiment(s) of the replaceable developer roller may advantageously extend the life of a BID  100  in which it is used. Upon failure or dissatisfaction with the replaceable developer roller  12 , rather than replacing the entire BID  100 , the roller  12  itself may be replaced. 
   Referring now to  FIG. 2 , an exploded side view of an embodiment of the replaceable developer roller apparatus  10  is depicted. The replaceable developer roller apparatus  10  includes a hollow cylindrical developer roller  12  having two opposed ends  14 ,  16 . The perspective view of the hollow cylindrical developer roller  12 , as shown in  FIG. 3 , illustrates its hollow, conductive material core  18 . It is to be understood that the core  18  may be made of any conductive material, examples of which include metal(s), plastic with conductive layer(s)/materials thereon and/or therein, and the like. In an embodiment, the core  18  is formed from one or more of aluminum, stainless steel, cold drawn steels with a coating thereon, and/or the like, and/or combinations thereof. 
   The core  18  may also be covered with a layer  19  of a conductive polymeric material, an example of which are polymeric materials incorporating additives such as metal particles, ionic charged particles, carbon black, graphite, and/or the like, and/or combinations thereof. In an embodiment, layer  19  is formed from a conductive urethane material. In the embodiment depicted in  FIG. 3 , the core  18  has an inner tapered wall section  20  located at each of the opposed ends  14 ,  16 . Opposed end  16  is generally referred to, but not shown in  FIG. 3 , however, opposed end  16  can be a mirror image of opposed end  14 . In an example, each of the inner tapered wall sections  20  has a taper angle ranging from about 3 degrees to about 7 degrees. In a further embodiment, the taper angle is about 5 degrees. 
   Referring back to  FIG. 2 , the replaceable developer roller  10  includes a drive assembly  22  selectively and operatively engageable with one of the opposed ends  14 ,  16  of the developer roller  12 . Generally, the drive assembly  22  includes a shaft  24 , a gear  26 , and a frusto-conical drive member  28 . 
   The shaft  24  of the drive assembly  22  has two opposed regions  30 ,  32 . The gear  26 , which has two opposed faces  34 ,  36 , is rotationally fixed to one of the opposed regions  30 ,  32  of the shaft  24 . It is to be understood that the gear  26  may be a spur gear, a helical gear, a worm gear, or the like. In an example, a helical gear is used as it may advantageously substantially reduce the noise produced by the roller  12  when in use. 
   The frusto-conical drive member  28  is rotationally fixed to the other of the opposed regions  32 ,  30  of the shaft  24 . It is to be understood that the frusto-conical drive member  28  is selectively, axially moveable between an engagement position and a disengagement position (the disengagement position is shown in  FIG. 2 ). Specifically, in the embodiment depicted in  FIG. 2 , the frusto-conical drive member  28  is axially translatable on the drive shaft  24  between the engagement position and the disengagement position. The frusto-conical drive member  28  may be made such that its shape is complementary with the inner tapered wall section  20  of one of the opposed ends  14 ,  16  of the developer roller  12 . When moved into the engagement position, the drive member  28  frictionally engages the tapered wall section  20  of opposed end  14  or  16 . 
   A spring  38  is disposed on the shaft  24  between one of the opposed faces  34 ,  36  of the gear  26  and the drive member  28 . Any suitable spring  38  may be used, and in an embodiment, the spring  38  is a compression spring, a helical spring, or the like. It is to be understood that the spring  38  advantageously biases the drive member  28  toward the engagement position. 
   First and second bearings  40 ,  42  are disposed on the drive assembly shaft  24 . One of the first and second bearings  40 ,  42  is disposed between the spring  38  and one of the opposed faces  36 ,  34  of the gear  26 ; while the other of the second and first bearings  42 ,  40  is disposed adjacent the other of the opposed faces  34 ,  36  of the gear  26 . The bearings  40 ,  42  may be roller bearings, sleeve bearings, journal bearings, needle bearings, ball bearings, or the like, and/or combinations thereof. For illustrative purposes, the first bearing  40  is shown between the spring  38  and the opposed face  36 , and the second bearing  42  is shown adjacent the other of the opposed faces  34 . 
   In an embodiment, a washer  44  may optionally be disposed between the spring  38  and the first bearing  40 . It is to be understood that the washer  44  has a high wear surface such that it may withstand, over time and use, pressure exerted when the apparatus  10  is in use and during replacement of developer roller  12 . In an embodiment where the washer  44  is not desired, it is to be understood that the spring  38  and first bearing  40  may optionally be designed with high wear surfaces to withstand such pressure as desired. Examples of suitable washers  44  include spacer washers, nylon washers, other polymeric washers (examples of which include polypropylene and high density polyethylene), and the like, and/or combinations thereof. 
   The drive assembly  22  also includes one or more drive member retaining clips  46  matingly engaged within an annular notch (not shown) that is defined in the other of the opposed regions  32 ,  30  of the shaft  24 . Generally, the annular notch is defined in the shaft  24  at the region  32  opposed to the region  30  where the gear  26  is rotationally fixed. It is to be understood that the clip(s)  46  is located in a position such that the frusto-conical drive member  28  is substantially prevented from axially disengaging from the shaft  24 . Examples of suitable clip(s)  46  include, but are not limited to, snap rings, C-clips, E-clips, and the like, and/or combinations thereof. In an embodiment, E-clip(s) are used. 
   The replaceable developer roller apparatus  10  also includes a spindle assembly  48  that is engageable with the other of the opposed ends  16 ,  14  of the developer roller  12 . The spindle assembly  48  has a shaft  50  with two opposed regions  52 ,  54 . A frusto-conical alignment member  56  is rotationally fixed to the spindle assembly shaft  50  at one of the opposed regions  52 ,  54 . In an embodiment, the frusto-conical alignment member  56  may be made such that its shape is complementary with the inner tapered wall section  20  of the other of the opposed ends  16 ,  14  of the developer roller  12 . It is to be understood that the frusto-conical alignment member  56  frictionally engages the respective inner tapered wall section  20  when the drive member  28  is in the engagement position. 
   The spindle assembly  48  may also include a bearing  58  on the shaft  50  between the alignment member  56  and the other of the opposed regions  54 ,  52 . It is to be understood that the bearing  58  may be any of the bearings described hereinabove. 
   Referring now to  FIG. 4 , an embodiment of the drive assembly shaft  24  is depicted with an embodiment of the frusto-conical drive member  28 . It is to be understood that in this embodiment, the frusto-conical drive member  28  is axially translatable on the drive shaft  24 . As depicted, the drive assembly shaft  24  is splined at opposed region  32 . A center bore  29  of the drive member  28  is splined complementarily to the splined drive assembly shaft  24 . It is to be further understood that the splined shaft  24  drivingly engages with the drive member  28 . 
   Referring now to  FIG. 5 , an embodiment of the method of replacing the embodiment of the developer roller  12  shown in  FIG. 2  in a printing device  1000  is depicted. The method generally includes moving the drive member  28  away from the developer roller  12  and compressing the spring  38 , as shown at reference numeral  60 ; moving the developer roller  12  out of engagement with the spindle assembly  48 , as shown at reference numeral  62 ; removing the developer roller  12  from apparatus  10 , as shown at reference numeral  64 ; and replacing the removed developer roller  12  with a new developer roller  12  by reversing the process, as shown at reference numeral  66 . 
   More specifically, the method may include axially moving the frusto-conical drive member  28  from its engagement with one of the opposed ends  14 ,  16  (end  14  as shown in  FIG. 2 ) of the developer roller  12 , such that it is disengaged therefrom. In this embodiment of the method, the drive member  28  moves axially independently of the drive shaft  24 . Further, the movement of the drive member  28  to the disengagement position may be accomplished by urging (which may be accomplished manually and/or via a common hand tool with a substantially flat head, such as, for example, a flat head screwdriver and/or the like) the drive member  28  out of the opposed end  14 ,  16  and toward the gear  26 . It is to be understood that when the drive member  28  is in the disengagement position, the spring  38  is compressed towards the gear  26 . 
   When the drive member  28  is in the disengagement position, the other of the opposed ends  16 ,  14  (end  16  as shown in  FIG. 2 ) of the developer roller  12  may be removed such that it is no longer engaging the frusto-conical alignment member  56 . The developer roller  12  may then be removed from the printing device  1000 . 
   In an alternate embodiment of the method, the developer roller  12  may be urged toward and with the drive member  28  such that the spring  38  is compressed, and the opposed end  16 ,  14  disengages from the alignment member  56 . Once the developer roller  12  is disengaged from the alignment member  56 , the other of the opposed ends  14 ,  16  may be removed such that it is no longer engaging the frusto-conical drive member  28  of the drive assembly  22 . The developer roller  12  may then be removed from the printing device  1000 . 
   Once the developer roller  12  is removed from the printing device  1000  using either of the above methods, one of the opposed ends  16 ,  14  of a new developer roller  12  may be engaged with the frusto-conical alignment member  56 . The frusto-conical drive member  28  may then be moved axially from the disengagement position such that the other of the opposed ends  14 ,  16  of the new developer roller  12  is engaged therewith. Axially moving the drive member  28  to the engagement position may be accomplished by allowing the spring  38  to urge the drive member  28  into the respective opposed end  14 ,  16  of the new developer roller  12 . 
   Alternately, once the developer roller  12  is removed from the printing device  1000  using either of the methods described further above, one of the opposed ends  14 ,  16  of a new developer roller  12  may be engaged with the frusto-conical drive member  28  while compressing spring  38 . The frusto-conical alignment member  56  may then be engaged with the other of the opposed ends  16 ,  14  of the new developer roller  12  by allowing the spring  38  to urge the drive member  28  and engaged roller end  14 ,  16  toward the spindle assembly  48 . 
   Referring now to  FIG. 6 , an alternate embodiment of the replaceable developer roller  10  is depicted. In this embodiment, the frusto-conical drive member  28  is both rotationally and axially fixed to the drive shaft  24  at an end  32 ,  30  opposed to the end  30 ,  32  where the gear  26  is rotationally fixed. The drive shaft  24  is axially translatable between the engagement position and the disengagement position (the disengagement position is shown in  FIG. 6 ). 
   In an example, the gear  26  is rotationally fixed to shaft  24  via a notch (not shown) in gear  26  and a pin (not shown) extending through the notch and into shaft  24 . In a further example, one of the opposed regions  30 ,  32  of the drive assembly shaft  24  is splined. A center bore  27  of the gear  26  is also splined such that it is complementary with the splined shaft  24 . It is to be understood that the splined shaft  24  drivingly engages with the gear  26 . 
   The drive assembly  22  includes a bearing housing  68  having the first bearing  40  therein. The bearing housing  68  is located along the shaft  24  between one of the opposed faces  36 ,  34  of the gear  26  and drive member  28 . The bearing housing  68  may recess the optional washer  44  therein and may also recess at least a portion of the spring  38  therein. 
   In this embodiment, the second bearing  42  is disposed on the shaft  24  between the spring  38  and the drive member  28 . In an example, the first bearing  40  is a roller bearing, a journal bearing, a needle bearing, or the like; and the second bearing  42  is a needle bearing, a journal bearing, or the like. 
   A selectively engageable locking mechanism  70  selectively, axially locks the drive assembly shaft  24  in the disengagement position. Examples of suitable locking mechanisms  70  include pin/aperture mechanisms, cams, threaded members, locking levers, and/or the like. 
   As shown in  FIG. 6 , the spindle assembly  48  may optionally include a washer  44  disposed on the spindle assembly shaft  50  between the bearing  58  and the opposed region  54 . While the washer  44  is not depicted in the spindle assembly  48  of  FIG. 2 , it is to be understood that the washer  44  may be used in any of the embodiments of the spindle assembly  48  disclosed herein. 
   Referring now to  FIG. 7 , an embodiment of the method of replacing the embodiment of the developer roller  12  shown in  FIG. 6  in a printing device  1000  is depicted. The method generally includes moving the drive shaft  24  away from the developer roller  12  and locking the lock mechanism  70 , as shown at reference numeral  72 ; moving the developer roller  12  out of engagement with the spindle assembly  48 , as shown at reference numeral  74 ; removing the developer roller  12  from the apparatus  10 , as shown at reference numeral  76 ; and replacing the removed developer roller  12  with a new developer roller  12  by reversing the process, as shown at reference numeral  78 . 
   More specifically, the method includes axially moving the frusto-conical drive member  28  with the drive shaft  24  from its engagement with one of the opposed ends  14 ,  16  of the developer roller  12 , such that it is disengaged therefrom. In this embodiment of the method, the movement of the drive member  28  and drive shaft  24  to the disengagement position may be accomplished by urging/pulling (which may be accomplished manually) the drive shaft  24  and drive member  28  out of the respective opposed end  14 ,  16  of the developer roller  12 . The drive shaft  24  may then be locked in the disengagement position via the locking mechanism  70 . 
   When the drive shaft  24  is locked in the disengagement position, the other of the opposed ends  16 , 14  of the developer roller  12  may be removed such that it is no longer engaging the frusto-conical alignment member  56  of the spindle assembly  48 . The developer roller  12  may then be removed from the printing device  1000 . 
   Once the developer roller  12  is removed from the printing device  1000 , one of the opposed ends  16 ,  14  of a new developer roller  12  may be engaged with the frusto-conical alignment member  56 . The drive shaft  24  may then be unlocked and the drive member  28  moved axially from the disengagement position such that the other of the opposed ends  14 ,  16  of the new developer roller  12  is engaged therewith. Axially moving the drive shaft  24  to the engagement position may be accomplished by unlocking the lock mechanism  70  and allowing the spring  38  to urge the drive member  28  into the respective one of the opposed ends  14 ,  16  of the new developer roller  12 . 
   Embodiment(s) of the present disclosure may advantageously be used in a printing device  1000  in order to extend the life of the BID  100  within that printing device  1000 . 
   While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.