Patent Publication Number: US-6986575-B1

Title: Automatic rotating media stripper carriage for a printer and method for maintaining a printer

Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The present invention relates to imaging devices, particularly to a stripper blade assembly for removing a print medium from the surface of a roller and/or an imaging drum of an imaging device, and more particularly to a printer assembly including a mechanism for automatic homing and rotating of a media stripper carriage. 
   2. Description of Related Art 
   In an imaging process an intermediate image is printed onto a print surface of a drum, the print surface generally having a release agent coated on the surface of the drum. The intermediate image is then transferred from the print surface onto a print medium, such as paper or transparency material, in a transfer fusing process. More specifically, the image is transferred onto the print medium by passing the medium between a drum having a surface and a transfix roller. Heat and pressure is applied to the medium in a contact region (pressure nip) between the drum and the roller such that the image is transferred from the drum to the medium. Such a transfer process causes the medium to tend to adhere to the surface of the drum. Thus, after a leading edge of the medium emerges from the pressure nip, the medium must be stripped from the drum and guided to the next set of transport rollers. 
   To strip the medium from the drum, strippers are generally used. For example, it is known to use multiple, spring loaded, plastic fingers that are presented to the drum and media at a specified point. A stripper may only contact the drum in a leading edge margin to avoid disturbing the fragile image that has recently been transferred to the media. The transfix stripper blade may be a passive stripper with constant engagement to the roller surface. When forming an image on both sides of the media (duplex prints) or, for example, when using a highly curled media, such as, for example, a light weight stock paper, the media may also “stick” to the transfix roller. Thus, a stripper may also be used in connection with transfix rollers. If there is any damage to the print medium, such as a bent corner, a bent leading edge, a cut in the media or any other blemish in the media, or error in the print process, the result may be a serious jam that is difficult to clear and may require an expensive service call. 
   Accordingly, in the event that maintenance of the printer is needed, or for any other reason, a user may have to remove the stripper from the device. For example, in the event that the media jams at the imaging drum, transfix roller, or elsewhere, a user may have to open the printer or copier to clear the jammed media before continuing use. Many times, in order to reach the jammed media, different parts of the device must first be removed and then returned after the jammed media is cleared. 
   For example, as described in U.S. Pat. No. 6,293,545 (herein incorporated by reference), a stripper blade assembly for removal of a print medium from an imaging drum of a printer is described. The stripper blade assembly uses a thin, durable, flexible blade and the assembly is removable and installable by a customer. The blade, that extends the width of the drum, is mounted on a blade holder. The blade holder is detachably mounted on a shaft having an over molded connector. The entire assembly rotates or otherwise moves to present the thin edge of the blade to the drum along the axial length of the drum in order to strip the leading edge of the print medium from the drum at the appropriate point in the print process. However, a customer is required to remove parts of the printer in order to reach an intended area of the printer to clear a jam and then must correctly replace the parts before being able to resume printing. 
   Likewise, in many common printers, a user is required to remove the stripper from the printer in order to gain access to a jam, or, for example, to clean the blade. After the stripper is removed, other parts of the printer may also pose an obstacle to reaching the jammed media. 
   After a user removes or moves the stripper and/or other parts, each of these parts must be re-installed or returned to its original location before the printer may be used again. Printers may not have a mechanism that would alert the user that all parts have not been properly re-installed. If all the parts are not re-installed or not re-installed correctly, the printer will jam again. 
   In other known printing systems, various parts of the printer, including the stripper, are not easily removable. Thus, a user must attempt to clear a jam, clean parts, or for whatever reason, work inside the printer without the benefit of being able to move parts that may be in the way. 
   Accordingly, the present invention provides a system and method wherein the stripper and other parts may be more easily reached for maintenance, cleaning, or the like, without removing parts of the printer or damaging the print media or the parts of the printer. 
   SUMMARY OF THE INVENTION 
   There is a need for improved access to a printer for cleaning, maintenance or repair. 
   There is a need for a printer wherein it is easy for a customer to reach the drum and/or transfix roller in the printer without the need to remove printer parts. 
   There is a need for easier access to the parts of a printer with a reduced opportunity for damaging the printer. 
   There is a need for a stripper that can be readily moved out of the way and includes a mechanisms to ensure the stripper moves back to its proper position by closing of a door of the imaging device. 
   The above and other advantages are achieved by various embodiments of the invention. 
   Accordingly, the present invention provides a printer assembly including a mechanism for automatic rotating of a media stripper carriage and a method for maintaining a printer. That is a media stripper carriage may be easily accessed and rotated so that a user may, for example, access a stripper blade of the stripper carriage without having to remove any parts of the printer. 
   More specifically, an active drum media stripper and a passive transfix roller media stripper are both connected to a stripper carriage that pivots about a shaft of a transfix roller. By allowing for pivoting of the stripper carriage about the transfix roller shaft, intermittent, active drum media stripping and access to media jams or blade cleaning is easily achieved. Because the system is pivoting about the transfix roller shaft, the passive transfix stripper maintains constant engagement with the transfix roller as the system is run through its range of motion. This system is actuated with a solenoid for stripping of the print medium from a drum and/or a transfix roller. In a preferred embodiment, the stripper carriage stops at an open position (jam clear position) after the user rotates the stripper carriage out of the way, for example, for jam access. When the user has completed the object task, for example, clearing the jam, the user may simply close a door of the printer, whereby the stripper carriage automatically rotates to a ready position in which the printer is ready for printing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features of the present invention will become apparent as the following description proceeds and upon reference to the drawings, in which: 
       FIG. 1  illustrates a rotatable stripper carriage in an embodiment of the present invention; 
       FIG. 2  illustrates a side view of a stripper carriage in a position in which a blade may scrape an image drum in an embodiment of the present invention; 
       FIG. 3  illustrates a side view of the stripper carriage in a position in which the stripper carriage is ready for printing in an embodiment of the present invention; 
       FIG. 4  illustrates a side view of the stripper carriage in a position in which a user may easily access the drum or stripper carriage for maintenance in an embodiment of the present invention; 
       FIG. 5  illustrates a rotatable stripper carriage of an imaging device in an embodiment of the present invention; 
       FIG. 6  is a flowchart illustrating a method for maintaining a printer in an embodiment of the present invention; 
       FIG. 7  illustrates a partially exploded view of a rotatable stripper carriage of an imaging device in an embodiment of the present invention. 
       FIG. 8  illustrates an inside view of a rotatable stripper carriage of an imaging device in an embodiment of the present invention. 
       FIG. 9  illustrates a cross-sectional view of a solenoid, solenoid bracket and lever arm of a stripper solenoid assembly in an embodiment of the present invention; 
       FIG. 10  illustrates an exploded view of the solenoid, solenoid bracket and lever arm of a stripper solenoid assembly in an embodiment of the present invention; and 
       FIG. 11  illustrates a compressed spring and lever arm of a rotatable stripper carriage in an embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIGS. 1–11  illustrate the components of a rotating media stripper carriage assembly  10  in an embodiment of the present invention. The assembly  10  includes a stripper carriage assembly  12  having a drum stripper blade  14  and a stripper carriage  18  which houses a transfix roller  15 , whereby the transfix roller  15  and the stripper carriage  18  rotate about a shaft  20 . The drum stripper blade  14  may be used to strip media  64  (see  FIG. 2 ), such as, for example, paper, from a surface  22  of the imaging drum  24 . Transfix ground pins  68  secure transfix load arms  70  to the drum. Referring also to  FIGS. 7 and 8 , the assembly  10  may further include a transfix roller stripper blade  17 . 
   In use, when a paper jam occurs, removal of the paper or cleaning of the drum stripper blade  14  or the transfix roller stripper blade  17  may be needed. Or, for any other reason, a user may open a door  70  of an imaging device  80 , such as, for example, a copier or printer, and swing the stripper carriage assembly  12  up and out of the way so that the jam, or parts that need maintenance, may be easily reached (see  FIG. 4 ). In an embodiment, the stripper carriage assembly  12  may be moved by use of a handle  25  attached to the stripper carriage  18 . For example, in an embodiment, when a user pulls the handle  25  in a backward direction, the stripper carriage assembly  12  begins to rotate about the shaft  20  of the transfix roller  15 . Other embodiments with means to move the stripper carriage assembly  12  may also be employed. For example, movement of the stripper carriage assembly  12  may be triggered by closing the door  70  via contact between the assembly  10  and the door  70 , or, for example, movement of the assembly  10  may be automated. 
   Referring again to  FIGS. 1–5  and  9 , in an embodiment of the present invention, a solenoid body  30  having a plunger  32  may actuate the assembly  10 . The plunger  32  may retract into the solenoid body  30  or extend outside of the solenoid body  30 . The solenoid body  30  is supported by a solenoid frame  33  attached to a solenoid bracket  38 . The solenoid bracket  38  may be mounted to an upper inner duplex guide  40  of the printer. The solenoid body  30 , the solenoid frame  33 , the solenoid bracket  38 , and the upper inner duplex guide  40  remain stationary relative to the rotatable assembly  10 . In an embodiment, in addition to supporting the solenoid bracket  38 , the upper inner duplex guide  40  may act as a media guide during the printing process. However, the solenoid bracket  38  may be attached to any stable part of the printer. Although the solenoid bracket  38  and the solenoid body  30  remain relatively stationary, the plunger  32  of the solenoid body  30 , a lever arm  36  and the assembly  10  may all be movable parts of the printer. The lever arm  36  may be attached to the plunger  32  of the solenoid body  30  at one end by a rivet  31 . The lever arm  36 , at another end, is in contact with the stripper carriage  18 . 
   When the solenoid body  30  is energized, the plunger  32  may be pulled into a solenoid body  30 . The solenoid body  30  is energized with DC current based on a specific timing after a paper path position sensor is tripped. The solenoid is de-energized after a set time has elapsed. In other words, the solenoid body  30  is energized with DC current after the media has been staged. That is, the media may be stopped with a leading edge of the media in between the transfix roller  15  and the imaging drum  24 . The solenoid body  30  is de-energized after the imaging drum  24  has rotated to a specific position. When the plunger  32  is pulled into the solenoid body  30 , the lever arm  36 , which is attached to the plunger  32 , is pulled such that the lever arm  36  is forced to rotate which in turn rotates the stripper carriage  18  forward in a clockwise direction until the stripper carriage  18  reaches a hard stop position  50 , as shown in  FIG. 2 . The stripper carriage  18  reaches the hard stop position  50  when the stripper carriage assembly  12  makes contact with the transfix ground pin  68 . In the hard stop position  50 , the drum stripper blade  14  is in position to strip the imaging drum  24 . The drum blade  14  deflects against the imaging drum  26  and provides the force needed to strip the media from the drum  24 . 
   When the solenoid body  30  is de-energized, a return spring  39 , located around the plunger  32  of the solenoid body  30 , provides a force to move the stripper carriage back from the hard stop position  50  to a ready position  54 . The return spring  39  provides the force by strain energy imparted on the return spring  39  when it is compressed by the plunger  32  and an e-ring  41  (see  FIG. 10 ). When the solenoid body  30  is de-energized, the compressive force on the return spring  39  is removed and the return spring  39  expands so as to return to its lowest energy state. The return spring  39  expands, causing the plunger  32  to protrude from the solenoid body  30 . The return spring  39  pushes on the e-ring  41  which pushes on the plunger  32 , which pushes on the rivet  31 , which pushes on the lever arm  36 , causing the lever arm  36  to rotate. The energized solenoid  30  creates a magnetic field which pulls the plunger  32  into the solenoid body  30 . This causes the return spring  39  to compress because the e-ring  41  which is connected to the plunger  32  puts a compressive force on the return spring  39 . 
   The return spring  39  is in a compressed state when the solenoid body  30  is energized and the plunger  32  is in a retracted position, as shown in  FIG. 2 , and is in an expanded state when the solenoid body  30  is de-energized and the plunger  32  is in an expanded position, as shown in  FIG. 3 . The ready position  54  is a position in which the parts of the printer are in position to continue with or start printing. The return spring  39  may be, for example, a conical compressing spring. 
   Referring to  FIG. 4 , in an embodiment of the present invention, in a jam clear position  52 , a user may easily access the drum  24 , drum stripper blade  14 , transfix roller  15 , and/or other parts of the printer. A force applied to a handle  25  may rotate the stripper carriage assembly  12  back in a counter clockwise direction, thereby rotating the stripper carriage  18 , which in turn rotates the lever arm  36 , which in turn pulls the plunger  32  from the solenoid body  30  and allows the return spring  39  to expand. Here, the stripper carriage  18  is rotated backward, in a counter-clockwise direction, about the shaft  20  of the transfix roller  15  to provide access to the drum stripper blade  14 , transfix roller stripper blade  17 , the surface  22  of the imaging drum  24 , as well as other areas of the printer. Counterclockwise rotation of the stripper carriage  18  may be stopped by interference with the upper inner duplex guide  40 . 
   In an embodiment of the present invention, a soft stop  56  is implemented to satisfy the functional and usability requirement of a movable but not removable stripper assembly  10 . A soft stop  56  creates a system in which there is enough force to locate the stripper carriage assembly  12  in its ready position  54 , but not so much force that a user is not able to move the stripper carriage assembly  12  past the soft stop  56 . To accomplish this, as shown in  FIGS. 9 and 11 , a compression spring  58  is preferably provided in the lever arm  36 . The return spring  39  creates the force necessary to rotate the lever arm  36  and the stripper carriage assembly  12  until the compression spring  58  contacts a mating surface  59  of the solenoid bracket  38 , this interface defines the soft spot  56 . This interface also defines the ready position  54  of the stripper assembly  10 . There is not enough force in the (now extended) return spring  39  to automatically compress the preloaded compression spring  58 . However, a user can easily create enough force to further rotate the stripper carriage assembly  12  back in a counter-clockwise direction, which compresses the compression spring  58  even farther. In this jam clear position  52 , the lever arm  36  is a follower and a surface  60  (see  FIG. 4 ) of the stripper carriage  18  acts as a cam. 
   The cam (the surface  60  of the stripper carriage  18 ) and follower lever arm  36  and stripper carriage  18  is designed so that the assembly  10  comes to rest in a “hands off” position  62  (see  FIG. 4 ). After a user pulls the handle  25 , rotates the stripper carriage assembly  12  to the jam clear position  52 , and then releases the handle  25 , the stripper carriage assembly  12  may rotate in a clockwise direction and come to rest in the hands off position  62 . In the hands off position  62 , the assembly  10  will be automatically returned to its ready position  54  when the user closes the door  70  of the imaging device  80 . For example, when a user closes the door  70  of the imaging device  80 , the stripper carriage assembly  12  is forced to rotate in a clockwise direction and will come to rest at the ready position  54 . More specifically, the cam surface  60  on the carriage assembly  10  and the spring force on the lever arm  36  work together to automatically return the carriage  12  to a “hands-off” intermediate position once the user has let go. This intermediate position is such that the carriage is properly positioned to interface with surfaces on the access door. When the access door is closed, surfaces on the door push (rotate) the carriage past an over-center position of the cam surfaces into the “ready” position. The hands off position is set by virtue of the cam  60  and follower mechanism finding a detent position where the follower (lever arm) comes to rest at the smallest radial position of the cam (back surface of the carriage). The system is inclined to rotate toward this low-energy state from the jam clear position. Therefore, it is nearly impossible for the user to fail to successfully return the parts of the imaging device to a ready position  54  after clearing a jam or after opening and then closing the door  70  for any other reason. 
   Referring again to  FIGS. 1–3 , in a ready position  54 , an outer diameter  22  (the surface  22 ) of the imaging drum  24  is illustrated. A media  64 , such as, for example, paper, is transferred between the drum  24  and the transfix roller  15 . Pressure is applied to the media  64  at a nip  66  between the transfix roller  15  and the drum  24 . Here, as the paper is moving forward, the transfix roller  15  rotates in a direction opposite to that of the paper. As the paper moves toward an exit, the solenoid body  30  energizes and throws the lever arm  36  such that the stripper carriage assembly  12  rotates until it hits the hard stops  68  (i.e. transfix ground pins  68 ) (see  FIG. 2 ). The drum stripper blade  14  engages the drum  24  and strips the media  64  from the drum  24 . After a leading edge of the paper gets past the drum stripper blade  14 , the solenoid body  30  disengages and the return spring  39 , around the plunger  32 , forces the stripper carriage assembly  12  back up into a ready position  54 . 
   Referring to  FIG. 2 , the hard stop position  50  is illustrated wherein the drum stripper blade  14  is engaged with the drum  24  and scrapes the drum  24  to remove the media  64  that may be attached thereto. In the event that there is a malfunction and the media  64  is not stripped off of the drum  24 , a user may need to manually remove the media  64  from the drum. 
   Referring to  FIG. 6 , an example flowchart for maintaining a printer is illustrated. To clear a jam, or to otherwise access a printer for maintenance, a user may open the door  70  of an imaging device, such as, for example, a printer, as shown at step S 10 . The user may then grasp the handle  25  to rotate the assembly  10  back in a counter clockwise position, as shown at step S 20 . Here the user may remove any jammed media, clean the blade or other parts of the printer, and/or perform any other required maintenance, as shown at step S 30 . If necessary, the user may further rotate the assembly  10  or may allow the assembly to rest in the hands off position  62 , as shown at step S 40 . Finally, the user may then manually return the assembly  10  as shown at step S 50  or may simply close the door  70 , thereby forcing the assembly  10  to rotate forward in a clockwise position to the ready position  54  for printing, as shown at step S 60 . 
   It is envisioned that the above described embodiments may be used in association with a number of different devices, such as, for example, printers, copiers, fax machines, and the like. Further, while the embodiments of the present invention are described above, it should be understood that the present invention need not be limited to those embodiments. On the contrary, the present invention is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the claims.