Abstract:
A method of loading a medium onto an imaging drum ( 300 ) mounted for rotation about an axis, the imaging drum having force providing points to provide an attractive force between the imaging drum and the medium. The steps of the method are: rotating the imaging drum ( 300 ) about the axis into a position such that force providing points are located out of a medium load position in which the medium to be loaded first contacts the imaging drum; and maintaining the imaging drum ( 300 ) in the position until the medium is in the medium load position. With the medium in the medium load position, rotating the imaging drum about the axis such that the force providing points engage with the medium causing the medium to engage with the imaging drum. Once the medium has engaged with the imaging drum, the medium is allowed to move and the imaging drum is rotated such that the medium is wrapped around and loaded onto the imaging drum ( 300 ).

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a method of loading media onto an imaging drum in an image processing apparatus. The invention includes a method of loading a medium onto an imaging drum in an image processing apparatus used to form a pre-press proof used in the printing industry.  
         BACKGROUND OF THE INVENTION  
         [0002]    Pre-press proofing is a procedure that is used mainly by the printing industry for creating representative images of printed material without the high cost and time that is required to actually produce printing plates and set up a high-speed, high volume, printing press to produce an example of an intended image. An image may require several corrections and be reproduced several times to satisfy or meet the customers requirements resulting in a large loss of profits and ultimately higher costs to the customer. An example of a system and method for pre-press proofing is described in commonly-assigned U.S. Pat. No. 5,341,159 or U.S. Pat. No. 5,268,708, the contents of which are incorporated herein by reference.  
           [0003]    One such commercially available image processing apparatus is arranged to form an intended image on a sheet of thermal print medium. Dye is transferred from a sheet of dye donor material to the thermal print medium by applying a sufficient amount of thermal energy to the dye donor sheet material to form the intended image. This image processing apparatus generally includes a material supply assembly or carousel, and a lathe bed scanning subsystem or write engine, which includes a lathe bed scanning frame, translation drive, translation stage member, printhead, load roller, imaging drum, and thermal print medium and dye donor sheet material exit transports.  
           [0004]    Operation of the image processing apparatus includes metering a length of the thermal print medium (in roll form) from the material assembly or carousel. The thermal print medium is then cut into sheet form of the required length and transported to the imaging drum. It is then wrapped around and secured onto the imaging drum. A load roller, which is also known as a squeegee roller, removes entrained air between the imaging drum and the thermal print medium or the thermal print medium and the dye donor material. Next, a length of dye donor material (in roll form) is metered out of the material supply assembly or carousel, and cut into sheet form of the required length. It is then transported to the imaging drum and wrapped around the periphery of the imaging drum. The load roller removes any air entrained between the imaging drum, thermal print medium and the dye donor material. The dye donor material is superposed in the desired registration with respect to the thermal print medium, which has already been secured to the imaging drum.  
           [0005]    The thermal print medium and the dye donor sheet material must be located on the imaging drum must be precisely positioned requiring that the lead edge of the thermal print medium and the dye donor sheet material be accurately controlled during and after the loading of the thermal print medium and the dye donor sheet material.  
           [0006]    After the dye donor sheet material is secured to the periphery of the imaging drum, the scanning subsystem or write engine provides the scanning function. This is accomplished by retaining the thermal print medium and the dye donor sheet material on the imaging drum while it is rotated past the printhead to form an intended image on the thermal print medium. The translation drive then traverses the printhead and translation stage member axially along the axis of the imaging drum in coordinated motion with the rotating imaging drum. These movements combine to produce the intended image on the thermal print medium.  
           [0007]    After the intended image has been formed on the thermal print medium, the dye donor sheet material is removed from the imaging drum without disturbing the thermal print medium beneath it. The dye donor sheet material is then transported out of the image processing apparatus. Additional dye donor sheet materials are sequentially superimposed with the thermal print medium on the imaging drum, further producing an intended image. The completed intended image on the thermal print medium is then unloaded from the imaging drum and transported to an external holding tray on the image processing apparatus.  
           [0008]    U.S. Pat. No. 5,777,658 discloses a system in which lift fins associated with the imaging drum are used to adjust the position of the medium relative to the imaging drum to enable the medium to be loaded and unloaded to the drum. However, although effective, this system requires the use of additional moving parts, which is undesirable.  
         SUMMARY OF THE INVENTION  
         [0009]    According to a first aspect of the present invention there is provided a method of loading a medium onto an imaging drum mounted for rotation about an axis, the imaging drum having force providing points to provide an attractive force between the imaging drum and the medium, the method comprising the steps of: rotating the imaging drum about said axis into a position such that the force providing points are located out of a medium load position in which the medium to be loaded first contacts the imaging drum; and maintaining the imaging drum in said position until the medium is in the medium load position.  
           [0010]    Preferably, the method further comprises the steps of driving the medium to the imaging drum until the medium is in the medium load position; and once the medium is in the medium load position, rotating the imaging drum about the axis such that the force providing points engage with the medium causing the medium to engage with the imaging drum.  
           [0011]    Once the medium has engaged with the imaging drum, the medium is allowed to move and the imaging drum is rotated such that the medium is wrapped around and loaded onto the imaging drum.  
           [0012]    Preferably, the force-providing points are vacuum points in communication with the interior of the imaging drum, which is itself in communication with a vacuum source.  
           [0013]    According to a second aspect of the present invention there is provided an imaging apparatus, comprising an imaging drum arranged for rotation about an axis, the imaging drum having force providing points to provide an attractive force between the imaging drum and a medium to be loaded thereon, wherein the imaging drum is controlled such that on loading of a medium, the drum is rotated abut the axis such that the force providing points are located out of a medium load position in which the medium to be loaded first contacts the imaging drum.  
           [0014]    The invention provides a method of loading media onto an imaging drum that removes the need for the lift fins disclosed in U.S. Pat. No. 5,777,658, and also removes the need for the multi-chambered vacuum drum described in U.S. Pat. No. 5,341,159. In addition, the need for vacuum level control in the imaging drum as described in U.S. Pat. No. 6,266,076 is overcome. Instead the imaging drum is positioned such that the force-providing points, such as vacuum holes are located out of the medium load position. This enables the medium to be moved into the medium load position with little or no influence of the vacuum holes in the imaging drum. By enabling the medium to be moved into the medium load position with little or no influence of the vacuum holes in the imaging drum, media can be accurately and conveniently loaded onto an imaging drum.  
           [0015]    Once the medium is driven into the correct medium load position it may be held in position by a media handling assembly including, for example, drive rollers, an articulating bar or other means known in the art. The imaging drum is moved into position such that as imaging drum moves the medium skids along the surface of the imaging drum until it is in the correct position, on the imaging drum so that the force-providing points engage with the medium. The medium is then allowed to move so that as the imaging drum rotates the medium is loaded onto the imaging drum. After the medium is loaded, the method may be repeated to load a second sheet of medium onto the imaging drum. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    A more complete understanding of the invention and its advantages will be apparent from the detailed description taken in conjunction with the accompanying drawings, wherein examples of the invention are shown, and wherein:  
         [0017]    [0017]FIG. 1 is a side view in vertical cross-section of an image processing apparatus suitable for use with the method of the present invention;  
         [0018]    [0018]FIG. 2 is an exploded, perspective view of an imaging drum suitable for use in the image processing apparatus of FIG. 1;  
         [0019]    [0019]FIGS. 3A to  3 D show the steps required for loading of medium onto an imaging drum, in accordance with the method of the present invention;  
         [0020]    [0020]FIG. 4 is a plan view of a imaging drum surface suitable for use in the image processing apparatus of FIG. 1;  
         [0021]    [0021]FIGS. 5A to  5 C are plan views of a imaging drum showing a sequence of placement for thermal print medium and dye donor sheet material according to the method of the present invention;  
         [0022]    [0022]FIG. 6 is a schematic side elevation view of an image processing apparatus suitable for use with the method of the present invention; and  
         [0023]    [0023]FIG. 7 is a front perspective view of a material supply carousel of a image processing apparatus shown in FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    In the following description, like reference characters designate like or corresponding parts throughout the several views. Also, in the following description, it is to be understood that such terms as “front,” “rear,” “lower,” “upper,” and the like are words of convenience and are not to be construed as limiting terms. Referring in more detail to the drawings, the invention will now be described.  
         [0025]    Turning first to FIG. 1, an image processing apparatus according to the present invention, which is generally referred to as  10 , includes an image processor housing  12 , which provides a protective cover for the image processing apparatus  10 . The image processing apparatus  10  also includes a hinged image processor door  14 , which is attached to the front portion of the image processor housing  12  and permits access to the two sheet material trays  50 . A lower sheet material tray  50   a  and upper sheet material tray  50   b  are positioned in the interior portion of the image processor housing  12  for supporting thermal print medium  32 , or an input image (not shown), thereon. Only one of the sheet material trays  50  will dispense the thermal print medium  32  out of the sheet material tray  50  to create an intended image (not shown) thereon. The alternate sheet material tray  50  a or b either holds an alternative type of thermal print medium  32 , or an input image (not shown), or functions as a back up sheet material tray  50  for thermal print medium  32 . In this regard, lower sheet material tray  50   a  includes a lower medium lift cam  52   a , which is used to lift the lower sheet material tray  50   a  and, ultimately, the thermal print medium  32  upwardly toward lower medium roller  54   a  and upper medium roller  54   b . When the medium rollers  54   a  and  54   b  are both rotated, the thermal print medium  32  is pulled upwardly towards a movable medium guide  56 . The upper sheet material tray  50   b  includes an upper medium lift cam  52   b  for lifting the upper sheet material tray  50   b  and, ultimately, the thermal print medium  32  towards the upper medium roller  54   b , which directs it toward the movable medium guide  56 .  
         [0026]    Continuing with FIG. 1, the movable medium guide  56  directs the thermal print medium  32  under a pair of medium guide rollers  58 . This engages the thermal print medium  32  for assisting the upper medium roller  54   b  in directing the thermal print medium  32  onto medium staging tray  60 . The medium guide  56  is attached and hinged to the lathe bed scanning frame  202  at one end, and is uninhibited at its other end for permitting multiple positioning of the medium guide  56 . The medium guide  56  then rotates the uninhibited end downwardly, as illustrated. The direction of rotation of the upper medium roller  54   b  is reversed for moving the thermal print medium  32 , which is resting on the medium staging tray  60 , under the pair of medium guide rollers  58  upwardly through an entrance passageway  204  and up to an imaging drum  300  according to the present invention.  
         [0027]    A media roll  30  of dye donor material  34  is connected to the medium carousel  100  in a lower portion of the image processor housing  12 , as shown in FIG. 1. Four media rolls  30  are ordinarily used, but, for clarity, only one is shown in FIG. 1. Each media roll  30  includes a dye donor material  34  of a different color, typically black, yellow, magenta and cyan. The dye donor materials  34  are ultimately cut into dye donor sheet materials  36  and passed to the imaging drum  300  for forming the medium from which dyes embedded therein are passed to the thermal print medium  32 . It should be noted that dye could take the form of pigments inks or colorants. In this regard, a medium drive mechanism  110  is attached to each media roll  30  of dye donor material  34 , and includes three medium drive rollers  112  through which the dye donor material  34  of interest is metered upwardly into a medium knife assembly  120 . After the dye donor material  34  reaches a predetermined position, the medium drive rollers  112  cease driving the dye donor material  34 . Two medium knife blades  122  positioned at the bottom portion of the medium knife assembly  120  cut the dye donor material  34  into dye donor sheet materials  36 . The lower medium roller  54   a  and the upper medium roller  54   b  along with the medium guide  56  then pass the dye donor sheet material  36  onto, medium staging tray  60  and ultimately to the imaging drum  300 .  
         [0028]    As shown in FIG. 1, a laser assembly  400  includes a quantity of laser diodes  402  in its interior. The laser diodes  402  are connected via fiber optic cables  404  to a distribution block  406  and ultimately to a printhead  500 . The printhead  500  directs thermal energy received from the laser diodes  402  to the dye donor sheet material  36 . This causes the dye donor sheet material  36  to pass the desired color to the thermal print medium  32 . The printhead  500  attaches to a lead screw (not shown), which provides axial movement along the longitudinal axis of the imaging drum  300  for transferring the data to create the intended image onto the thermal print medium  32 .  
         [0029]    To form an intended image onto the thermal print medium  32 , the imaging drum  300  rotates at a constant velocity. The printhead  500  begins at one end of the thermal print medium  32  and traverses the entire length of the thermal print medium  32  if needed for completing the transfer process for the particular dye donor sheet material  36  resting on the thermal print medium  32 . After the printhead  500  completes the transfer process for the particular dye donor sheet material  36  resting on the thermal print medium  32 , the dye donor sheet material  36  is removed from the imaging drum  300  and transferred out of the image processor housing  12  via a skive or ejection chute  16 . The dye donor sheet material  36  eventually comes to rest in a waste bin  18  for removal by the user. The above-described process is then repeated for the other three media rolls  30  of dye donor materials  34 . The thermal print medium  32  with the intended image thereon is then removed from the imaging drum  300  and transported out of the image processor housing  12 .  
         [0030]    Optionally the operation of the image processing apparatus  10  could include metering a length of the thermal print medium (in roll form)  32  from the medium carousel  100 . The thermal print medium  32  is then measured and cut into sheet form of the required length and transported to the imaging drum  300 . It is then registered, wrapped around, and secured onto the drum  300  using the load roller  350 . Next, a length of dye donor material (in roll form)  34  is metered out of the medium carousel  100 , measured, and cut into sheet form of the required length. Then transported to the imaging drum  300  and wrapped around the imaging drum  300  using the load roller  350 , so that it is superposed in the desired registration with respect to the thermal print medium  32 , which has already been secured to the imaging drum  300 .  
         [0031]    After the dye donor sheet material  36  is secured to the periphery of the imaging drum  300 , a scanning system  210  such as a lathe bed scanning system or write engine provides the scanning function. This is accomplished by retaining the thermal print medium  32  and the dye donor sheet material  36  on the spinning imaging drum  300  while it is rotated past the printhead  500  that will expose the thermal print medium  32 . The lead screw then traverses the printhead  500  axially along the axis of the imaging drum  300  in coordinated motion with the rotating imaging drum  300 . These movements combine to produce the intended image onto the thermal print medium  32 .  
         [0032]    [0032]FIG. 2 shows an example of an imaging drum  300  for use in the image processing apparatus  10  of FIG. 1. The imaging drum  300  includes means for providing an attractive force between the imaging drum  300  and the medium. In this case, the imaging drum  300  has a cylindrical-shaped imaging drum housing  302 , which includes a hollowed-out interior portion  304 . The attractive force is provided by a number of vacuum holes  306  in the wall of the imaging drum  300  that communicate vacuum from interior of the imaging drum  300  to the exterior of the imaging drum  300 . The imaging drum  300  further includes a number of vacuum grooves  332  on the surface of the imaging drum  300 . Vacuum is applied from the hollow-out interior portion  304  of the imaging drum  300  through vacuum grooves  332  and the vacuum holes  306 . The vacuum supports and maintains the position of the thermal print medium  32  and the dye donor sheet material  36 , even as the imaging drum  300  rotates.  
         [0033]    The ends of the imaging drum  300  are closed by a vacuum end plate  308 , and a drive end plate  310 . The drive end plate  310  is provided with a centrally disposed drive spindle  312 , which extends outwardly. The vacuum end plate  308  is provided with a centrally disposed vacuum spindle  318  extending outwardly.  
         [0034]    The imaging drum  300  is provided with vacuum by connection to a high-volume vacuum blower (not shown), which is capable of producing 50-60 inches of water at 60-70 CFM. The vacuum blower (not shown) provides the vacuum to the imaging drum  300  required during loading, scanning and unloading of the thermal print medium  32  and the dye donor sheet materials  36  to create the intended image.  
         [0035]    [0035]FIGS. 3A to  3 D show the steps in the method of the present invention of loading thermal print medium  32  onto an imaging drum  300 . In this case, the imaging drum  300  has an axially extending flat portion  322 , which preferably extends approximately 8 degrees of the circumference of the imaging drum  300 . A number of lead vacuum holes  33  and trail vacuum holes  35  are provided in the axially extending flat  322 . The holes on the axially extending flat portion  322  are categorized as lead vacuum holes  33  and trail vacuum holes  35  with reference to their position relative to each other and their presentation to the thermal print medium  32  being loaded. It can be seen that as the imaging drum  300  rotates in the direction of arrow  37 , the lead vacuum holes  33  are presented to the thermal print medium  32  before the trail vacuum holes  35 .  
         [0036]    Referring to FIG. 3A, a thermal print medium  32  (not shown in FIG. 3A) is loaded onto the imaging drum  300  with the help of a loading mechanism  39 . Load roller  350  is optionally also provided. Prior to engagement of the thermal print medium  32  with the imaging drum  300  (the position in FIG. 3A) the imaging drum  300  is rotated about its longitudinal axis such that the lead vacuum holes  33  and trail vacuum holes  35  are not in the thermal print medium  32  load position. In other words, the lead vacuum holes  33  and trail vacuum holes  35  are positioned such that when the thermal print medium  32  is advanced by the loading mechanism  39  so that it is in close proximity to the imaging drum  300 , the lead vacuum holes  33  and trail vacuum holes  35  do not interfere with the thermal print medium  32 . With the imaging drum  300  in this position, the thermal print medium  32  is advanced into the thermal print medium  32  load position in which the leading edge of the thermal print medium  32  is in close proximity to the imaging drum  300 . Although not necessarily stationary, the imaging drum  300  is maintained in a position with the force providing points out of the thermal print medium  32  load position.  
         [0037]    Once the thermal print medium  32  is moved into the thermal print medium  32  load position as shown in FIG. 3B, the thermal print medium  32  is held in position by the loading mechanism  39 . The loading mechanism  39  may include drive rollers, an articulating bar or any other suitable means known in the art which are not shown. With the thermal print medium  32  held in position, the imaging drum  300  is rotated about its longitudinal axis into position such that as imaging drum  300  rotates, the thermal print medium  32  skids along the surface thereof. Once the imaging  300  drum reaches the position shown in FIG. 3C, the thermal print medium  32  is released by the loading mechanism which enables the thermal print medium  32  to be loaded onto the imaging drum  300  as it continues to rotate. Once the thermal print medium  32  is loaded dye donor sheet materials  36  can be loaded using the same method so that the arrangement of FIG. 3D is achieved. The arrangement of FIG. 3D shows the thermal print medium  32  loaded onto the imaging drum  300  with a dye donor sheet material  36  loaded on top of thermal print medium  32 .  
         [0038]    In the example of an imaging drum  300  shown in FIG. 4, the outer surface of the imaging drum  300  is provided with an axially extending flat  322 , which preferably extends approximately 8 degrees of the imaging drum  300  circumference. The imaging drum  300  is provided with donor support rings  324 , which form a radial recess  326  (see FIG. 2). This recess extends radially from one side of the axially extending flat  322  around the imaging drum  300  to the other side of the axially extending flat  322 , from approximately one inch from one end of the imaging drum  300  to approximately one inch from the other end of the imaging drum  300 . Although a preferred embodiment herein does include an axially extending flat  322  and a radial recess  326 , the present invention need not include either.  
         [0039]    As shown in FIGS. 5A to  5 C, the thermal print medium  32  when mounted on the imaging drum  300  is seated within the radial recess  326 . Therefore, the donor support rings  324  have a thickness, which is substantially equal to the thickness of the thermal print medium  32  seated there between. In this embodiment, this thickness is 0.004 inches. The purpose of the radial recess  326  on the surface of the imaging drum  300  is to eliminate any creases in the dye donor sheet material  36 , as the materials are drawn down over the thermal print medium  32  during the loading of the dye donor sheet material  36 . This ensures that no folds or creases will be generated in the dye donor sheet material  36 , which could extend into the image area and seriously adversely affect the intended image. The radial recess  326  also substantially eliminates the entrapment of air along the edge of the thermal print medium  32 , the vacuum holes  306  in the imaging drum  300  surface cannot always ensure the removal of the entrapped air. Any residual air between the thermal print medium  32  and the dye donor sheet material  36  can also adversely affect the intended image.  
         [0040]    An alternate example of an imaging system suitable for use with the method of the present invention is illustrated in FIG. 6: a laser thermal proofer  11 . The laser thermal proofer  11  comprises generally a material supply assembly  90 , a sheet cutter assembly  82 , a sheet transport assembly  91 , an imaging drum  300 , a printhead  500 , receiver exit assembly  22  and a donor exit assembly  24 .  
         [0041]    Referring to FIGS. 6 and 7, the material supply assembly  90  comprises a medium carousel  100  mounted for rotation about a horizontal axis  102  The medium carousel  100  comprises a vertical circular plate  40  having a plurality of material support spindles  42  cantilevered outwardly from and equally spaced about the front face of the vertical circular plate  40 . Each of the material support spindles  42  is arranged to carry a media roll  30  of material for use on the imaging drum  300 .  
         [0042]    In an alternate method of loading medium onto the imaging drum  300 , the imaging drum  300  is moved such that the load points are in the medium load position with no vacuum supplied to imaging drum  300  (vacuum blower off) once the thermal print medium  32  is moved to the correct position vacuum is applied (vacuum blower turned on) thus securing the thermal print medium  32 . The imaging drum  300  then moves loading the thermal print medium onto the imaging drum  300 . Next the dye donor sheet material  36  is loaded onto the imaging drum  300  using the method previously described.  
         [0043]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims by a person of ordinary skill in the art, without departing from the scope of the invention. While preferred embodiments of the invention have been described using specific terms, this description is for illustrative purposes only. It is intended that the doctrine of equivalents be relied upon to determine the fair scope of these claims in connection with any other person&#39;s product which fall outside the literal wording of these claims, but which in reality do not materially depart from this invention.  
       Parts List  
       [0044]    [0044] 10 . Image processing apparatus  
         [0045]    [0045] 11 . Laser thermal proofer  
         [0046]    [0046] 12 . Image processor housing  
         [0047]    [0047] 14 . Hinged image processor door  
         [0048]    [0048] 16 . Ejection chute  
         [0049]    [0049] 18 . Wastebin  
         [0050]    [0050] 30 . Media roll  
         [0051]    [0051] 32 . Thermal print medium  
         [0052]    [0052] 33 . Lead vacuum holes  
         [0053]    [0053] 34 . Dye donor material  
         [0054]    [0054] 35 . Trail edge vacuum holes  
         [0055]    [0055] 36 . Dye donor sheet material  
         [0056]    [0056] 37 . Arrow  
         [0057]    [0057] 39 . Loading mechanism  
         [0058]    [0058] 40 . Vertical circular plate  
         [0059]    [0059] 42 . Material support spindles  
         [0060]    [0060] 50 . Sheet material tray  
         [0061]    [0061] 50   a . Lower sheet material tray  
         [0062]    [0062] 50   b . Upper sheet material tray  
         [0063]    [0063] 52 . Medium lift cam  
         [0064]    [0064] 52   a . Lower medium lift cam  
         [0065]    [0065] 52   b . Upper medium lift cam  
         [0066]    [0066] 54 . Medium rollers  
         [0067]    [0067] 54   a . Lower medium roller  
         [0068]    [0068] 54   b . Upper medium roller  
         [0069]    [0069] 56 . Movable medium guide  
         [0070]    [0070] 58 . Medium guide rollers  
         [0071]    [0071] 60 . Medium staging tray  
         [0072]    [0072] 80 . Sheet cutter assembly  
         [0073]    [0073] 90 . Material supply assembly  
         [0074]    [0074] 91 . Sheet transport assembly  
         [0075]    [0075] 100 . Medium carousel  
         [0076]    [0076] 102 . Horizontal axis  
         [0077]    [0077] 110 . Medium drive mechanism  
         [0078]    [0078] 112 . Medium drive rollers  
         [0079]    [0079] 120 . Medium knife assembly  
         [0080]    [0080] 122 . Medium knife blades  
         [0081]    [0081] 204 . Entrance passageway  
         [0082]    [0082] 210 . Scanning system  
         [0083]    [0083] 300 . Imaging drum  
         [0084]    [0084] 302 . Imaging drum housing  
         [0085]    [0085] 304 . Hollowed out interior portion  
         [0086]    [0086] 306 . Vacuum holes  
         [0087]    [0087] 308 . Vacuum end plate  
         [0088]    [0088] 310 . Drive end plate  
         [0089]    [0089] 312 . Drive spindle  
         [0090]    [0090] 318 . Vacuum spindle  
         [0091]    [0091] 322 . Axially extending flat  
         [0092]    [0092] 324 . Donor support rings  
         [0093]    [0093] 326 . Radial recess  
         [0094]    [0094] 332 . Vacuum grooves  
         [0095]    [0095] 350 . Load roller  
         [0096]    [0096] 400 . Laser assembly  
         [0097]    [0097] 402 . Laser diode  
         [0098]    [0098] 404 . Fiber optic cables  
         [0099]    [0099] 406 . Distribution block  
         [0100]    [0100] 500 . Printhead