Patent Publication Number: US-6663239-B2

Title: Microwave applicator for inkjet printer

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to printing methods and apparatus, and particularly relates to ink drying as applied in the context of inkjet printing operations. 
     Inkjet printing produces print imaging by propelling ink droplets onto media. A variety of inkjet printing apparatus have evolved, but generally share in the common characteristic of rendering an image by depositing liquid on a media substrate. As such, inkjet printing methods and operations sometime include or even require drying of media, i.e., drying liquid ink following application to media as print imaging. 
     Inkjet drying techniques include passing media including wet print imaging through heated rollers. Unfortunately, the application of heat energy and consequent drying to wet media when in a curved condition, i.e., as wrapped around a roller, often results in undesirable cockling and/or buckling or curvature of output. As a result, such media often suffers in quality and in some cases requires additional processing to “flatten” the media. 
     Use of microwave drying in an inkjet printing process is known. For example, U.S. Pat. No. 5,220,346 issued Jun. 15, 1993 and entitled Printing Process With Microwave Drying illustrates ink formulations and use of a microwave drying as applied in the context of inkjet printing. U.S. Pat. No. 5,563,644 issued Oct. 8, 1996 to Isganitis et al. and entitled Inkjet Printing Process with Microwave Drying also shows use of microwave radiation to dry ink in an inkjet printing context. 
     Generally, application of heat energy to wet ink volatilizes the ink and thereby dries print imaging produced thereby. Unfortunately, volatizing ink produces ink vapor which undesirably contaminates a printing operation and inhibits further drying. More particularly, volatilized ink compounds should be carried away from a printing operation so as to prevent excessive buildup of such compounds as volatilized or as settling back into liquid form. Thus, many ink drying methods and apparatus must carry away volatized ink compounds so as to avoid contamination of the printing operation. Accordingly, many ink drying methods and apparatus employ a separate system for carrying away and suitably venting volatized ink compounds. Volatilized ink compounds also inhibit further drying when accumulated at the media surface. In other words, volatized ink compounds tend to accumulate at a “boundary layer” of the media surface. This body of volatilized ink tends to prevent further volatilization of ink and thereby either inhibit or completely stop further drying of print imaging. Accordingly, ink drying methods and apparatus often “scrub” this boundary layer to remove a body of volatilized ink compounds from the media surface and thereby promote further productive drying of print imaging. 
     SUMMARY OF THE INVENTION 
     The present invention combines microwave heating apparatus and techniques with airflow techniques to improve overall ink drying in an inkjet printing operation. Microwave drying techniques, while effective, produce at the media surface a “boundary layer” of vaporized ink inhibiting or significantly impairing further productive drying thereat. The present invention incorporates airflow pathways within a microwave applicator to scrub this boundary layer and thereby promote more efficient drying by microwave radiation. In addition, the present invention, through use of selected air pathways in and about a heat zone, takes away undesirable ink vapors produced by the drying process and thereby eliminates need for separate apparatus dedicated specifically to ink vapor removal. 
     The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation of the invention, together with further advantages and objects thereof, may best be understood by reference to the following description taken with the accompanying drawings wherein like reference characters refer to like elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: 
     FIG. 1 illustrates in perspective a typical inkjet printer including a microwave applicator drying station according to a preferred embodiment of the present invention. 
     FIG. 2 illustrates, separately from the printer of FIG. 1, the microwave applicator drying station of FIG.  1 . 
     FIG. 3 illustrates the microwave applicator drying station of FIG. 2 as taken along lines  3 — 3  of FIG.  2 . 
     FIG. 4 illustrates partially and in section a portion of the microwave applicator drying station of FIG. 3 as taken along lines  4 — 4  of FIG.  3 . 
     FIG. 5 illustrates partially and in section a portion of the microwave applicator drying station of FIG. 3 as taken along lines  5 — 5  of FIG.  3 . 
     FIG. 6 illustrates the microwave applicator drying station of FIG. 3 as taken along lines  6 — 6  of FIG.  3 . 
     FIGS. 7 and 8 illustrate schematically alternative or combinable forms of the microwave applicator drying station of FIGS. 1-6 including use of a heat exchange and/or heat recycling in operation thereof. 
     FIG. 9 illustrates an alternative form of microwave applicator under the present invention organized as a serpentine waveguide with multiple heat zones and scrubbing zones provided thereby. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a typical inkjet printing mechanism, specifically an inkjet printer  20 . The present invention will be illustrated in the context of or as applied to a typical inkjet printing mechanism, e.g. in the context of or as applied to inkjet printer  20  of FIG.  1 . It will be understood, however, that printer components and particular component architectures vary from model to model and that the present invention applies across a variety of specific inkjet printing mechanism implementations. 
     Printer  20  includes a chassis  22 . Within chassis  22 , a print media handling system  24  supplies sheets of media (not shown in FIG. 1) to the printer  20 . Media may be of a variety of generally sheet-form materials, but will be referenced herein as paper or media for the purpose of describing the present invention. Handling system  24  moves media through a print zone  25  located along a feed path within chassis  22 . The feed path begins at a feed tray  26  and ends at an output area  28 . A variety of media transport mechanisms and techniques are known. Generally, such mechanisms and techniques include a picking device for collecting individual media from tray  26  and a set of various driven and pinch rollers propelling media along the feed path, through printer  20 , and into output area  28 . 
     As described more fully hereafter, the present invention concerns drying media following application of print imaging in print zone  25 . As such, printer  20  operation will be described herein primarily with respect to media handling at or downstream from print zone  25 , i.e., generally after application of print imaging to media therein. 
     In print zone  25 , media moves longitudinally along the feed direction  50  and receives print imaging formed by projected ink droplets originating from a supply in a replaceable inkjet cartridge, such as a black inkjet cartridge  30  and/or a color inkjet cartridge  32 . Generally, cartridges  30 ,  32 , or “pens” as referenced by those familiar with the art, hold a selected ink formulation suitable for application to a selected media or particular print job. A variety of ink formulations has evolved across a variety of uses and variety of available media. 
     Cartridges  30  and  32  each carry a print head, individually referenced as print heads  34  and  36 , respectively, projecting ink droplets toward print zone  25 . Each print head  34  and  36 , at its bottom surface, presents an orifice plate (not shown) with a plurality of nozzles formed therethrough. Combining replaceable ink cartridges with print heads is well known in the inkjet printing art and has contributed to the success of inkjet printers as industrial, office, and personal printers. Print heads  34  and  36 , for example, are thermal inkjet print heads. Other types of print heads include piezoelectric print heads. 
     Print heads  34  and  36 , implemented as thermal inkjet print heads, each include a plurality of resistors forming a resistive network associated with the print head nozzles. Energizing a selected resistor quickly heats ink near a nozzle opening and, suddenly, a bubble of gas forms. In this manner, an inkjet nozzle “fires.” The bubble propels or ejects a droplet of ink at the nozzle, i.e. ink positioned between the nozzle opening and heated resistor. The droplet flies toward a sheet of media suitably positioned in print zone  25 . Application of print imaging according to a given print job includes coordinating the position of cartridges  30  and  32  within print zone  25 , coordinating the position of media within print zone  25 , and “firing” the nozzle arrays within print heads  34  and  36  according to print imaging data. 
     A carriage  38  holds cartridges  30  and  32 , along with the corresponding print heads  34  and  36 , respectively. Carriage  38  reciprocates or “scans”, i.e., moves laterally back and forth, through print zone  25 . Positioning cartridges  30  and  32  during a print job includes controlled reciprocation through print zone  25  and along a scan axis  41  parallel to a lateral axis  52 . A laterally-positionable carriage trolley  35  (shown partially) and a guide rod  40  establish movement of carriage  38  back and forth laterally through print zone  25 . Guide rod  40  defines scanning axis  41  within print zone  25 . More particularly, guide rod  40  is a rigid smooth-surfaced structure along which carriage  38  rides. Trolley  35  couples to carriage  38  and moves carriage  38  reciprocally back and forth through print zone  25 . In this particular inkjet printer embodiment, trolley  35  includes a laterally disposed toothed belt  37  suspended between a driven gear (not shown) near one end of print zone  25  and an idling gear (not shown) at the opposite end of print zone  25 . Thus, coupling carriage  38  to a point on belt  37  and driving belt  37  propels carriage  38  reciprocally as a trolley motor (not shown) alternates directions of rotation for belt  37 . 
     Cartridges  30  and  32  selectively deposit one or more ink droplets on print media located in the print zone  25  in accordance with instructions received via a conductor strip  42  from a printer controller, such as a microprocessor which may be located within chassis  22  and indicated generally by reference number  44 . Controller  44  may receive an instruction signal from a host device, which is typically a computer, such as a personal computer. 
     The print head carriage motor and the paper handling system drive motor operate cooperatively in response to printer controller  44  and in a manner well known to those skilled in the art. The printer controller  44  may also operate in response to user inputs provided through a keypad  46 . A monitor coupled to the host computer may be used to display visual information to an operator, such as the printer status or a particular program being run on the computer. Personal computers, their input devices, such as a keyboard and/or a mouse device, and monitors are all well known to those skilled in the art. 
     As well appreciated in the art, ink droplets projected onto media in print zone  25  as liquid sometimes require drying to fully set print imaging produced thereby. Many ink formulations have been developed for improving drying time for inkjet printing applications. In additional to ink formulations, certain methods of printing have evolved to improve ink drying time in inkjet printing applications. Further, some inkjet printers include heating devices through which media pass following application of print imaging. Ink formulations, drying mechanisms, and printing techniques fully optimized for ink drying time, however, often present undesirable side effects. There typically exists some compromise between drying time and other print imaging quality requirements. 
     Thus, most inkjet printing operations improve by improving, i.e., reducing, dry time for ink-based print imaging without significantly compromising other print imaging quality requirements. 
     Thus, printer  20  operation improves by placing a drying station  100  following print zone  25 . By incorporating a drying station  100  into printing operations conducted by printer  20 , print imaging, i.e., liquid droplets deposited on media in print zone  25  more quickly achieve a suitably dry state for proper output from printer  20 . In other words, printed output should reach a certain level of dryness before release from printer  20 . Thus, drying station  100  applies heat energy to printed media just following, i.e., downstream from, print zone  25  and thereby more quickly promotes a suitably dry state thereof, i.e., suitably dry for release from printer  20  as output. Though illustrated as a component of printer  20 , it will be understood that drying station  100  as described herein may be provided as a separate drying unit, i.e., a unit substantially as shown in FIGS. 2-9 and through which media may be fed after application of print imaging thereon. As described more fully hereafter, drying station  100  includes media transport mechanisms and thereby facilitates use as a separate unit, i.e., allows a user to insert media therein and automatically feed media therethrough while applying heat energy. As illustrated in FIG. 1, drying station  100  operates within a shroud  100   a,  releases output at slot  100   b,  and receives input at slot  100   c  FIG.  2 . Further details of drying station  100 , i.e., that located within shroud  100   a,  will be described more fully with reference to FIGS. 2-6. 
     FIGS. 2-6 illustrate in more detail various views of drying station  100  as separated from the remaining portions of printer  20 . Shroud  100   a,  shown only partially in FIG. 2, may be provided to surround the components of drying station  100  as illustrated in FIGS. 2-6 and include front and rear slots  100   b  and  100   c  for passing media  114  therethrough. Thus, FIG. 2 illustrates drying station  100  components within shroud  100   a.  FIG. 3 illustrates a front view of drying station  100  as taken along lines  3 — 3  of FIG.  2 . FIGS. 4 and 5 are partial sectional views showing air inflow at slot formations in the microwave applicator  102  of drying station  100 . FIG. 6 is a top view of the microwave applicator as taken along lines  6 — 6  of FIG.  3 . 
     Applicator  102  includes a microwave source  104  and a water load  106  coupled together by way of waveguide  108 . Waveguide  108  is, in essence, a rectangular extrusion structure such as may be formed by extrusion. For example, aluminum extruded as a waveguide for microwave applicators is known. In operation, microwave source  104 , e.g., a magnetron, directs radiant microwave energy toward water load  106  along waveguide  108 . Waveguide  108  includes a longitudinal pathway  110  therethrough. More particularly, pathway  110  comprises a slot  110   a  in a front-facing wall  108   a  of waveguide  108  and a slot  110   b  in a rear-facing wall  108   b  of waveguide  108 . Thus, longitudinal pathway  110  allows passage of media  114  through applicator  102  generally along axis  51  and in the media feed direction  50 . 
     Microwave applicators similar to, but not identical to, applicator  102  are commercially available. Generally, magnetrons and waveguides are available from many manufacturers according to well-established standards and known modes of operations. For example, manufacturers typical of such providers include Cober-Mugge and Toshiba. Many different companies offer microwave magnetrons and waveguides ready for use in a variety of applications. The present invention may be implemented by use of many of these microwave applicators by incorporating into such devices collection of air, e.g., by coupling the waveguide to a vacuum source. 
     A belt  112  carries media  114  along pathway  110  and through waveguide  108  for drying of print imaging just applied in print zone  25 . FIG. 2 illustrates the relative position of print zone  25 , i.e., an upstream position relative to applicator  102 . In practice, a useful distance between print zone  25  and applicator  102  is on the order of 50 mm, i.e., the rear slot  110   b  of applicator  102  being located approximately 50 mm from print zone  25  along the feed direction  50 . 
     Belt  112  is a perforated belt and includes a drive mechanism  117  propelling belt  112  along pathway  110 , i.e., along the feed direction  50 . As belt  112  passes along pathway  110  of waveguide  108 , it carries thereon media  114  as collected from print zone  25  of printer  20 . Belt  112  may be constructed from a variety of materials depending on a particular implementation of the present invention. Because belt  112  passes through waveguide  108 , it should withstand the microwave energy passing therealong. In this regard, belt  112  could be microwave “transparent” to minimize its interaction with microwave energy passing through waveguide  108 . Alternatively, the composition of belt  112  may be taken into account in the heating aspects provided by drying station  100 . More particularly, a metallic or partially metallic belt  112  will heat within the waveguide  108  and thereby contribute to application of heat energy to media  114  resting thereon. As will be discussed more fully hereafter, perforations  112   a  in belt  112  in combination with application of vacuum to selected portions of microwave applicator  102  enable belt  112  to engage media  114  by vacuum force and thereby serve as a media feed mechanism. 
     Belt drive mechanism  117  may be provided according to a variety of architectures depending on relative positioning of various components and constraints such as minimum belt  112  radius of curvature allowed. While illustrated herein as being supported on four separate shafts  117   a  and corresponding gears  117   b  carried thereon, it will be appreciated that other arrangements may be provided including a similar loop-architecture, but including only two shafts  117   a  and a set of larger-diameter gears or rollers on each shaft  117   a.  The upward-facing portion of belt  112  carrying media  114  thereon, may be extended rearward and into print zone  25  as necessary to accommodate integrated media support therethrough or to accommodate larger-diameter, and fewer, rollers or gears  117   b.    
     In any case, belt  112  is perforated at apertures  112   a  and includes an upward-facing portion moving along passageway  110  and supporting media  114  thereon. Generally, belt  112  should be maintained in tension through pathway  110  and should be of width greater than media  114  resting thereon. Maintaining belt  112  in tension through pathway  110  creates a flat surface upon which media  114  rests during the drying process. As a result, media  114  dries in a flattened condition and thereby possesses less curl or buckling as is often found in other drying systems, e.g., such as systems drying media while in a curved condition. 
     Applicator  102  includes along waveguide  108  a perforated floor  120 . Floor  120  includes an array of apertures  120   a.  Pathway  110  bifurcates waveguide  108  into an upper chamber  122   a  and a lower chamber  122   b.  A vacuum chamber  124  is located below floor  120 . Vacuum chamber  124  couples fluidly to lower chamber  122   b  by way of apertures  120   a.  A vacuum source  130  couples to lower chamber  124  and draws air therefrom. This in turn draws air from lower chamber  122   b  by way of perforations  120   a  in floor  120 . An inlet conduit  130   a  couples chamber  124  and vacuum source  130 . An outlet conduit  130   b  couples to an exhaust  130   c.  Inlet conduit  130   a  routes around belt  112 , e.g., taken from the back wall  108   b  of waveguide  108  and routed along behind and then around belt  112 . As will be described more fully hereafter, vacuum source  130  collects from waveguide  108  vaporized ink as taken from the drying process occurring within the heat zone  125  of waveguide  108 . Accordingly, vacuum source  130 , as fluidly coupled to the interior of waveguide  108 , collects undesirable vaporized ink material and conveys such material to exhaust  130 . No separate ventilation system need be included to carry away undesirable ink vapors. Manipulating the distribution and size of perforations  120   a  in combination with controlling the magnitude of vacuum applied to vacuum chamber  124  provides opportunity to control the magnitude of airflow from upper chamber  122   a  into lower chamber  122   b  as well control the relative air pressures therebetween. In practice, apertures  120   a  can be 1-3 mm in diameter and distributed throughout floor  120 . Generally, apertures  120  should be large enough to prevent significant vacuum differential between upper chamber  122   a  and lower chamber  122   b  when no media  114  rests on belt  112  within applicator  102 . 
     With pathway  110  situated intermediate chambers  122   a  and  122   b,  air drawn from waveguide  108  and into vacuum chamber  124  originates exterior of waveguide  108 . More particularly, air drawn out of applicator  102  by means of vacuum  130  originates at slots  110   a  and  110   b  of applicator  102 , i.e., taken from ambient air surrounding applicator  102 . With no media resting on belt  112 , no significant vacuum differential exists between chambers  122   a  and  122   b.  With media  114  resting on belt  112 , however, many of the apertures  112   a  are closed by media  114 . As a consequence, a significant pressure differential develops between upper chamber  122   a  and lower chamber  122   b.  More particularly, a negative pressure develops in lower chamber  122   b  and a relatively less negative pressure develops in upper chamber  122   a.  As a result, media  114  is held by vacuum force against the upward-facing surface of belt  112 . Furthermore, airflow taken from applicator  102  includes vaporized ink as scrubbed away from media  114  and carried away from the drying station  100  by vacuum source  130 . In this maimer, applying a vacuum source to a microwave applicator according to the present invention both provides assistance in media transport as well as vapor transport, i.e., taking-away undesirable ink vapors. 
     Microwave transparent non-porous end caps  105 , e.g., quartz plates, seal each end of waveguide  108 . More particularly, caps  105  mount at each end of upper chamber  122   a  and lower chamber  122   b.  These microwave transparent end caps are positioned in face-to-face relation to the microwave source  104  and microwave load  106 . End caps  105  should be non-porous, i.e., create an air-tight seal at the ends of waveguide  108 . In this manner, vacuum applied to the interior of waveguide  108  results in airflow into applicator  102  only at slots  110   a  and  110   b.  In other words, end caps  105  provide air-tight seals for the otherwise tubular structure of waveguide  108 . Because most microwave applicators do not make use of vacuum forces applied thereto, such microwave transparent end caps are typically not found in conventional microwave applicators. 
     Thus, application of vacuum at or near the under surface of perforated belt  112  draws media  114  onto belt  112 . Belt  112  thereby “grabs” media  114  by vacuum force and constitutes, at least with respect to that portion of belt  112  within applicator  102 , a media-engaging and media-propelling transport belt. In other words, as belt  112  and media  114  pass through applicator  102 , that length of belt  112  and media  114  within applicator  102  couple together by vacuum force. Belt  112 ,as incorporated into printer  20 , contributes to the overall printer  20  feed mechanism by propelling media  114  through applicator  102  and into ouput area  28 . As such, upstream media feed mechanisms, e.g., of printer  20 , need only advance media sufficiently past print zone  25  to reach station  100 . When used as an independent drying station, a user need only insert the leading edge of media into rear slot  110   b.  Belt  112  then engages and transports media through applicator  102  by vacuum grip. Important to note, the coupling between media  114  and station  100  is a “non-contact” coupling with respect to the upper-facing side of media  114 . In other words, station  100  does not contact and thereby avoids degrading print imaging just-applied in print zone  25  and not yet set, i.e., not yet sufficiently dry, to prevent smudging by contact. 
     Application of heat energy to media containing liquid ink vaporizes and thereby dries print imaging formed by the ink. Unfortunately, this process can be self-defeating due to formation of a “boundary layer” of vapor at the surface of the drying media. In other words, upon vaporization the ink tends to hang in vapor form just above the surface of media  114 . As a consequence, this inhibits, or in some cases completely stops, further vaporization of ink and thereby stops further productive drying of print imaging. As a result, the boundary layer must be “scrubbed” to remove a body of stagnant ink vapor thereat. 
     Air inrush  210  at slots  110   a  and  110   b  in the vicinity of such a boundary layer breaks up and scrubs the boundary layer and thereby exposes for further vaporization remaining ink on the media surface yet to be vaporized. FIGS. 4-6 illustrate such airflow in more detail. In FIGS. 4-6, belt  112  moves in the feed direction  50 , but is maintained in tension and flat by means of a rearward directed force  200  being less than a forward directed force  202 . For example, drive mechanism  117  should include sufficient horizontal bias between supports, e.g., rollers or gears  117   b,  holding that portion of belt  112  within guideway  108  to maintain belt  112  and media  114  resting thereon in a well-flattened condition. With particular reference to FIG. 4, air inrush  210   a  along the upper edge of slot  110   a  enters upper chamber  122   a.  Preferably, air inrush  210   a  into chamber  122  is primarily above belt  112  and media  114 . Accordingly, waveguide  108  may be fitted with a flange or lip  216   a  along the bottom edge of slot  110   a  and include thereon a Teflon™ plate  218   a.  Belt  112  slides over plate  218   a.  Preferably, this creates to some extent a seal along the bottom edge of slot  110   a  relative to belt  112 . The gap  220   a  between the top edge of slot  110   a  and the upper-facing surface of media  114  can be minimized to produce more velocity in air inflow  210   a  and greater “scrubbing” of media  114  as it leaves drying station  100 . 
     FIG. 5 illustrates a sectional view similar to FIG. 4, but showing air inrush  210   b  at slot  110   b  and a Teflon™ plate  218   b  on lip  216   a  along the bottom edge of slot  110   b.  Air inrush  210   b  comes into waveguide  108  at the initial formation of ink vapors in the boundary layer, and thereby contributes desirably to turbulence therein. In contrast, air inrush  210   a  at slot  111   a  substantially scrubs entirely the boundary layer at its most complete state of formation, i.e., as media  114  leaves drying station  100  a boundary layer of ink vapor is at its maximum, but scrubbed away by air inrush  210   a.  As a result, media  114 , still holding heat energy, can more readily vaporize any remaining ink from print imaging held thereby just as the boundary layer is scrubbed off at slot  110   a.    
     Microwave transparent ribs or louvers  212  (FIG. 6) direct airflow within waveguide  108 . In other words, microwave transparent structures  212  may be incorporated within applicator  102 , more particularly within waveguide  108 , to better direct airflow therein without interfering with microwave transmission therethrough. 
     Apertures  120   a  in floor  120  and apertures  112   a  in belt  112 , as well as louvers  212 , establish an overall airflow pattern. Controlling various air pressures and airflow magnitudes can be accomplished by relative sizing of apertures  112   a  and apertures  120   a  as well as potentially including dams as sidewalls for path  110  through waveguide  108 . In other words, walls abutting the edges of belt  112  force more air, or a controlled greater amount of air, through apertures  112   a  in belt  112 . Variation in dam size will vary the amount of airflow reaching apertures  120   a  directly or reaching apertures  120   a  by way of apertures  112   a.    
     FIG. 7 illustrates use of a heat exchanger  300 . Generally, water in the load  106  is circulated through the heat exchanger  300 . An air blower  302  forces air through heat exchanger  300  and thereby takes-away heat energy from water load  106 . Heat energy taken from the heat exchanger  300  is then applied to the slots  110   a  and  110   b,  e.g., such as by providing outlet vents  304  in the vicinity of slots  110   a  and  110   b.  Thus, a heated source for air inrush  210   a  and  210   b  at slots  110   a  and  110   b,  respectively, may be provided by vents  304 . In this manner, heat developed during the drying process is conserved by recycling heat energy back into applicator  102 . 
     FIG. 8 illustrates use of heat recycling by taking air from applicator  102 , filtering such air at filter  310 , applying such air to vacuum  130 , and directing the exhaust  130   c  from conduit  130   b  of vacuum  130  into slots  110   a  and  110   b  of applicator  102 . In this manner, vaporized ink collected from applicator  102  is removed from the airflow entering vacuum source  130  by means of filter  310  as interposed between vacuum source  130  and applicator  102 , i.e., along conduit  130   a.  The exhaust conduit  130   b  taken from vacuum source  130  thereby holds significant heat energy as taken from applicator  102 . Directing such heated air back for uptake as inrush  210   a  and  210   b  at slots  110   a  and  110   b,  respectively, conserves heat energy and further enhances ink drying. 
     FIG. 9 illustrates a serpentine waveguide  108 ′ as a series of applicators  102  interconnected by means of 180 degree waveguide turns. This establishes a larger drying station  100 ′ including a series of heat zones  125  along feed path  50 . In FIG. 9, a series of applicators  102  lie transverse to feed path  50  as described herein above. An overall serpentine waveguide  108 ′ is established by coupling applicators  102  by 180 degree waveguide turns. Thus, pathways  110  for each applicator  102  align and belt  112  passes through each of slots  110   a  and  110   b  therealong. Vacuum  130  couples to various portions of waveguide  108 ′ to draw vaporized ink therefrom and to couple together media resting on belt  112  as described above. While not specifically illustrated in FIG. 9, it will be understood that a vacuum chamber below waveguide  108 ′ couples to the remainder of waveguide  108 ′ by means of a perforated floor, e.g., similar to floor  120  as described herein above. Vacuum  130  thereby pulls from waveguide  108 ′ vaporized ink. Furthermore, air taken into waveguide  108 ′ enters waveguide  108 ′ at slots  110   a  and  110   b  of each applicator  102 . As a result, media passing through the series of applicators  102  receives significant scrubbing action at each of slots  110   a  and  110   b  as it moves along an overall feed path  50  therethrough. 
     Generally, in operation a variety of parameters may be adjusted to achieve an overall desired drying of media  114 . Thus, variation in the number of and size of apertures  120   a  and  112   a  as well as an overall magnitude of vacuum force applied will establish the basic air pressure differentials and airflow needed. Also, various ink formulations may be used to facilitate more rapid drying by microwave radiation. Finally, multiple applicators may be employed, e.g., such as a serpentine waveguide  108 ′ as illustrated in FIG. 9, to increase the amount of heat energy applied to a given media  114 . Depending on design specifications, i.e., how quickly one wishes to dry media  114  and/or how many passes through drying station  100  are acceptable, one can manipulate the amount of power applied to source  104 , amount of vacuum pressure, speed of belt  112 , type of ink used, and distribution and size of apertures  120   a  and  112   a  to achieve an overall drying time and number of drying passes objective. 
     Thus, an improved inkjet drying station has been shown and described. Drying moisture from inkjet media requires a heat source to raise temperature of the ink, a mass transfer system to remove vapors and scrub the boundary layer, and a non-contact media transport system to move media through the dryer. In accordance with the present invention, all three systems required for inkjet media drying are provided in the drying station  100  as described herein. Drying station  100  combines all three systems, i.e., heating, vapor transport, and non-contact media transport, into one compact system using less power and area to complete the same task. The microwave chamber or waveguide  108  may be provided in a relatively narrow dimension, e.g., on the order of 2 inches, along axis  51 , i.e., along the media feed direction  50 . This saves space and time. Because the applicator is substantially enclosed, this provides a closed volume, i.e., chambers  122   a  and  122   b,  to use as a vacuum chamber. Pulling the vacuum from the bottom chamber  122   b  creates a “paper-transport” capable vacuum belt. For proper operation, sizing the air passages on the sides of the belt allows minimal airflow and creates a pressure differential between the top and bottom of belt  112 . This not only traps ink vapors which are generally difficult to control in traditional drying systems, but also provides a mechanism sweeping away the ink vapors in controlled fashion. This effectively eliminates the need for a separate vapor collection system as is often found in traditional inkjet drying stations. Furthermore, because the vacuum pulls air across the media, the present invention scrubs the boundary layer of the media and thereby promotes more efficient drying rates. Finally, the vacuum established in applicator  102  reduces pressure over the area being dried, this reduced pressure decreases the boiling point for ink on the media therein and thereby increases drying rates. 
     It will be appreciated that the present invention is not restricted to the particular embodiment that has been described and illustrated, and that variations may be made therein without departing from the scope of the invention as found in the appended claims and equivalents thereof.