Abstract:
An image transfer system, including a member for supporting print media, the member including a pair of sidewalls depending therefrom, a pair of end caps, wherein one end cap is connected to the sidewalls at an end thereof and the other end cap is connected to the opposite end of the sidewalls, and a heating element disposed against the underside of the member and in contact with each of sidewalls and end caps.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to commonly-assigned U.S. patent application Ser. No. 09/768,956, entitled “RSVP Handling in 3G Networks,” filed on Jan. 24, 2001 the disclosure of which are incorporated herein by reference. 
     REFERENCE TO PRIORITY APPLICATIONS 
     This application claims priority from and incorporates by reference the following commonly-assigned provisional patent applications 60/275,354. 
     TESTING THIRD HEADING 
     This application claims priority from and incorporates by reference the following commonly-assigned provisional patent applications 60/275,354. 
    
    
     BACKGROUND 
     In the ink jet printing process, suitable support of the print media during printing aids in achieving acceptable print quality. Such support can include holding sheet media flat against a media supporting member, or platen, to ensure the ink maintains suitable properties during printing. 
     In addition, it may be desirable that a media sheet be heated uniformly as it rests on the printer platen, in order to achieve acceptable print quality. A technique, in pursuit of this goal, is to heat the platen to a suitable temperature. This is sometimes accomplished by the use of heating strips disposed against the sidewalls of the platen. While this technique results in effective heating of areas of the platen surface, it can fail in some instances to provide uniform heating over the platen surface. The result can be a diminution in print quality because of temperature gradients across the platen producing unevenly heated media sheets. 
     Where the term “image transfer system” is used in this description, the term is meant to encompass a variety of such devices, including printers, facsimile devices and scanners. For convenience, the term “printer” will be used in this written description but it should be understood that the description is intended broadly, to cover such other devices. 
     Another factor adversely affecting print quality may be a failure to draw the media sheet against the platen in a uniform manner. This is especially the case at the ends of the platen where air passes under media edges, thereby tending to raise the media away from the platen 
     Airflow at the media edges allows cool air to pass under the edges as the air flows generally toward the center of the media for evacuation. This airflow can produce an uneven temperature distribution across the media as portions of the media are raised away from the heated platen. Again, the result adversely impacts print quality. In addition, if air flows freely under media edges, a potential develops whereby the edges lifting from the platen surface may contact printheads thereby causing print defects, paper jams and, in some cases, damage to the printer. 
     SUMMARY OF THE INVENTION 
     An image transfer system includes a member for supporting print media, the member including a pair of sidewalls depending therefrom, a pair of end caps, wherein one end cap is connected to the sidewalls at an end thereof and the other end cap is connected to the opposite end of the sidewalls, and a heating element disposed against the underside of the member and in contact with each of sidewalls and end caps. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     Embodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles thereof. 
     FIG. 1 is a perspective view of a platen that is constructed according to an embodiment of the present invention; 
     FIG. 2 is a perspective view of the platen of FIG. 1 showing the underside thereof; 
     FIG. 3 is a partial view of the left side of platen of FIG. 1; 
     FIG. 4 is a partial of the left side of the platen of FIG. 1 showing end caps; 
     FIG. 5 is a partial view of the left side of platen of FIG. 1 showing the end caps, a heating element and an elastomeric seal; 
     FIG. 6 is a partial view of the left side of platen of FIG. 1 showing a portion of the surface thereof; 
     FIG. 7 is a view taken along the line  7 — 7  of FIG. 6; 
     FIG. 8 is a view taken along the line  8 — 8  of FIG. 6; 
     FIG. 9 is a perspective view of a vacuum plug that is constructed according to the embodiment of the present invention; 
     FIG. 10 is a partial view of the underside of platen of FIG. 1, showing the vacuum plug of FIG. 9 in place; 
     FIG. 11 is a perspective view of another embodiment of a vacuum plug that is constructed according to an embodiment of the present invention; and 
     FIG. 12 is a partial view of the right side of the platen of FIG. 1 showing the vacuum plug of FIG. 11 in place. 
    
    
     DETAILED DESCRIPTION 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiment is to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. 
     In the following detailed description and in the several figures of the drawings, like elements are identified with like reference numerals. 
     Referring now to the drawings and in particular to FIGS. 1-5, there is shown a member or platen, generally referred to by the reference numeral  10 , that is constructed according to an embodiment of the present invention. The platen  10  is of elongated rectangular shape having a planar top surface  12  that, during a printing process, supports a media sheet, such as the sheet  45 , shown in FIGS. 6 and 12. A plurality of substantially parallel, spaced apart grooves  14 - 17  is disposed on the platen top surface  12 , between a platen left side, generally indicated by the reference numeral  41 , and a platen right side, generally indicated by the reference numeral  42 . 
     A pair of sidewalls  13  and  18  is integrally connected with, and depends from, a bottom surface  11  of the platen  10 . End caps  31  and  32  are disposed on the right side  42 , and the left side  41 , of the platen  10 . 
     The end caps  31  and  32  are in intimate contact with the ends of the sidewalls  13  and  18  at end cap flat inner surfaces  33  and  35 . They are in intimate contact, also, with the bottom surface  11  of the platen  10 . The sidewalls  13  and  18 , end caps  31  and  32 , and the platen bottom surface  11  form five sides of a box, generally referred to by the reference numeral  21 . 
     It will be noted, with reference to FIGS. 1 and 2, that a vacuum box  19  is located under the platen  10 . It contacts the sidewalls  13  and  18  and the end caps  31  and  32 . A continuous elastomeric seal  36  seals the sidewalls and end caps  31  and  32  at arcuate outer surfaces  33   a  and  35   a  to ensure a leak tight configuration. It will be noted, with reference to FIG. 4, that each of the end caps  31  and  32  includes an upper portion  30  and a lower portion  30   a , as shown in FIG. 4, with respect to the end cap  31 . 
     During printing, air is evacuated from the grooves  14 - 17 . The air flows through apertures or openings in the platen  10 , such as the opening  21   a , from whence the air is pumped via a J-tube  23  out of the vacuum box  21 . The J-tube is sealingly connected to the sidewall of the vacuum box  19  at a medial opening  24  thereof. 
     As best shown in FIGS. 1,  2  and  5 , a heating element, or heater  34 , is disposed in intimate contact with the bottom surface  11  of platen  10 , the sidewalls  13  and  18  and the end caps  31  and  32 . The heater  34  imparts heat to the platen  10  along a continuous strip to provide improved uniformity of heating to the platen. In this manner, the platen ends  41  and  42  are maintained at substantially the same temperature as the central portion of the platen  10 , thereby ensuring that media disposed on the platen are heated more evenly. Platens, without the heat-conducting end caps  31  and  32  of the present embodiment of the invention, may be heated in a non-uniform manner so that media edges are cooler than the center of the media. 
     In an advantage provided by the present embodiment, not only do the end caps  31  and  32  improve print quality, they enable the platen  10  and the dependent sidewalls  13  and  18  to be extruded in one piece. As a result, a less expensive platen can be formed. The platen top surface  12  includes a datum  20  for helping to locate the platen  10  in a printer (not shown). In a preferred embodiment of the invention, to ensure good heat conduction to the platen edges  41  and  42 , the end caps  31  and  32  may be constructed of copper alloy, aluminum or composites containing carbon fibers, with copper alloy presently preferred. 
     As mentioned above, it is advantageous during printing for at least some types of print media to be heated to enable the ink to maintain good properties during printing. In this regard, it is desirable to prevent air from outside the platen  10  edges to flow under the media sheet during printing. FIGS. 6-12 depict the structure and function of two types of vacuum plugs. First considered will be vacuum plugs  70  and  70   a.    
     With reference to FIG. 9, the vacuum plug  70  includes a member or body  72  having a handle  73  extending from a back thereof and tines  74 - 77  extending from the body  72 , opposite the handle  73 . A mounting slot  71  is formed in the body  72 . It will be understood that the vacuum plug  70   a  is identical to the plug  70  in structure and function, having identical elements. As these elements appear in FIG. 10, their reference numerals are identical to counterparts in the plug  70 , except the numerals having the lower case “a” following the numeral. 
     The vacuum plugs  70  and  70   a  prevent air from flowing from the left side  41  of the platen  10  and under the media as the media are receiving ink. In accomplishing this, the vacuum plugs  70  and  70   a  function as bottom-insert plugs to block edge-to-edge airflow through the grooves  14 - 17 . This function can be understood by referring to FIG. 6 where there is shown a partial view of the left side  41  of the platen  10 . The print media sheet  45 , shown in phantom, has an edge  46 , and in a narrower version, an edge  48 . It will be noted that openings  53 - 56  are formed in the grooves  17 ,  16 ,  15  and  14 , respectively. 
     The openings  53 - 56  extend through the platen  10  and they are aligned adjacent the edge of the media sheet  46  in a line perpendicular to the axes of the grooves  14 - 16 . In a similar manner, openings  63 - 66  are formed in the grooves  17 ,  16 ,  15 , and  14 , respectively, and are disposed adjacent the end of the media sheet  48 . The openings  63 - 66  are aligned parallel to their counterpart openings  53 - 56 . 
     The function of the openings  53 - 56  and  63 - 66 , and their relationships to the plugs  70  and  70   a , will be understood by reference to FIGS. 7,  8  and  10 . The sectional view of FIG. 7 shows the grooves in an unblocked condition. On the other hand, the sectional view of FIG. 8, taken along a line outside the margin  46  of the sheet  45 , shows the vacuum plug  70  in place and having the tines  77 ,  76 ,  75  and  74  extending into the grooves  14 - 17 , and openings  53 - 56 , respectively. 
     The method of attachment of the plug  70  is shown in FIG. 10 where it will be seen that a fastener, such as a screw  79 , is utilized to secure the plug  70  to the bottom side  11  of the platen  10 . In a similar manner, the vacuum plug  70   a  is attached to the bottom side  11  by a fastener, or screw  79   a . By referring to FIG. 6, it will be understood that the tines of the vacuum plug extend into, and obstruct airflow through the openings  53 - 56  or  63 - 66 . 
     It will be noted that since the openings  53 - 56  are just within the margin  46  of the sheet  45 , and the openings  63 - 66  are just within the margin  48 , the use of the vacuum plugs  70  and  70   a  provides a passive, capacity of system adjustment. 
     With reference now to FIGS. 11 and 12, the airflow blocking function of the vacuum plug  80  will be discussed. The plug  80  includes a body  81  from which extend tines  14   a - 17   a . An opening  25   a  corresponds to an opening  26  in the platen  10  to enable installation of the vacuum plug  80 . FIG. 12 shows the right side edge  42  of the platen  10 . Here, the media sheet  45  is depicted in the justified condition, on the right side of the platen  10 . The plug  80  is installed in the platen  10  so that the plug body  81  fits in a recess  25  and the tines  14   a - 17   a  extend, respectively, into the grooves  14 - 17  to block airflow from the right side edge  42  medially toward the center of the platen  10 . 
     In summary, the vacuum plug  80  functions as a side-inserted vacuum plug to block edge-to-edge airflow on the justified side  42  (right side) of the platen  10 . 
     It will be evident that there are additional embodiments and applications which are not disclosed in the detailed description but which clearly fall within the scope of the present invention. The specification is, therefore, intended not to be limiting, and the scope of the invention is to be limited only by the following claims.