Patent Publication Number: US-11027562-B2

Title: Positive pressure plenum system for transport belts in a printing device

Description:
The present disclosure relates generally to printing devices and, more particularly, to a plenum system that provides positive pressure for transport belts in a printing device. 
     BACKGROUND 
     Printing devices can be used to print images on print media. The print media can be fed through the printing device along a transport path and imaging path to have the image printed. The transport path can use belts to transport the print media below print heads. In some designs, the transport belt may use a plenum that provides a vacuum to help keep the print media against the transport belt as the print media moves under the print heads. As a result, the print media may remain in place while being moved by the transport belt such that ink can be accurately dispensed onto the print media. 
     Current generation printers can transport print media at very high speeds and process hundreds and thousands of sheets of print media per print job. The high volume printing can cause the transport belts to continuously move against a plenum. As a result, the constant friction between the transport belt and the plenum can cause wear on the transport belt causing frequent replacement of the transport belt. Frequent replacement of the transport belt may lead to higher costs and lower production. 
     In addition, the friction between the transport belt and the plenum can cause the transport belt to move inefficiently. The friction may be caused by constant contact of the transport belt against the plenum or due to ink build up on the surface of the plenum. The high amount of friction may cause the motors driving the transport belt to work harder to move the transport belt due to the friction. Consuming more power may lead to higher energy costs and quicker wear of the motors driving the transport belt. 
     SUMMARY 
     According to aspects illustrated herein, there are provided a printing module and a method for controlling the same. One disclosed feature of the embodiments is a printing module comprising a plurality of printheads, a transport belt located below the plurality of printheads to transport print media below the plurality of printheads, wherein the transport belt comprises a plurality of vacuum openings, and a positive pressure plenum system, wherein the positive pressure plenum system provides a positive air flow to create an air interface between a top surface of the positive pressure plenum system and a bottom surface of the transport belt, wherein the positive pressure plenum system provides a negative air flow to create a vacuum through the plurality of vacuum openings of the transport belt to hold the print media against the transport belt. 
     Another disclosed feature of the embodiments is a method for controlling a printing module. In one embodiment, the method detects a print media entering the printing module to receive a print job, provides a vacuum, in response to the print media that is detected, via a positive pressure plenum that provides a negative air flow through a plurality of vacuum openings of a transport belt to hold the print media against the transport belt as the transport belt moves the print media below a plurality printheads, and provides a positive air flow, in response to the print media that is detected, through the positive pressure plenum to provide an air interface between a bottom surface of the transport belt and a top surface of the positive pressure plenum as the transport belt moves across the top surface of the positive pressure plenum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The teaching of the present disclosure can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a block diagram of an example printing device of the present disclosure; 
         FIG. 2  illustrates a side view of a printing module that includes printheads, a transport belt, and a positive pressure plenum of the present disclosure; 
         FIG. 3  illustrates an isometric cross-sectional view of the positive pressure plenum that shows tunnels associated with the positive pressure openings and the vacuum openings; 
         FIG. 4  illustrates a top view of the transport belt on the positive pressure plenum of the present disclosure; 
         FIG. 5  illustrates another embodiment of the positive pressure plenum of the present disclosure; 
         FIG. 6  illustrates a flowchart of an example method for operating a printing module of the present disclosure; and 
         FIG. 7  illustrates a high-level block diagram of an example computer suitable for use in performing the functions described herein. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. 
     DETAILED DESCRIPTION 
     The present disclosure is related to a registration system of a positive pressure plenum for transport belts in a printing device and a method for operating the same. As discussed above, current generation printers can transport print media at very high speeds and process hundreds and thousands of sheets of print media per print job. The high volume printing can cause the transport belts to continuously move against a plenum. As a result, the constant friction between the transport belt and the plenum can cause wear on the transport belt causing frequent replacement of the transport belt. Frequent replacement of the transport belt may lead to higher costs and lower production. 
     In addition, the friction between the transport belt and the plenum can cause the transport belt to move inefficiently. The friction may be caused by constant contact of the transport belt against the plenum or due to ink build up on the surface of the plenum. The high amount of friction may cause the motors driving the transport belt to work harder to move the transport belt due to the friction. Consuming more power may lead to higher energy costs and quicker wear of the motors driving the transport belt. 
     Embodiments of the present disclosure provide a positive pressure plenum that can provide positive pressure to reduce the friction between the transport belt and the positive pressure plenum. For example, the positive pressure may provide an air interface between the transport belt and the positive pressure plenum as the transport belt moves across the top of the positive pressure plenum. 
     In addition, the vacuum openings of the positive pressure plenum may be aligned with openings of the transport belt. The positive pressure openings of the positive pressure plenum may be positioned under portions of the transport belt without holes. As a result, a vacuum may still be applied to the print media to hold the print media against the transport belt. 
     The air from the positive pressure may move across the bottom surface of the transport belt and into the vacuum openings of the positive pressure plenum. As a result, the positive pressure plenum of the present disclosure may provide more efficient movement of the transport belt with less friction and less wear on the transport belt. 
       FIG. 1  illustrates a block diagram of an example printing device  100  of the present disclosure. The printing device  100  may be any type of printing device such as a multi-function device (MFD), a copy machine, laser printer, an ink jet printer, and the like. 
     In one embodiment, the printing device  100  may include a feeder module  104 , a printing module  102 , and a finishing module  106 . It should be noted that the printing device  100  has been simplified for ease of explanation. The printing device  100  may include additional components and modules that are not shown. For example, the printing device  100  may include a duplex paper path, a digital front end, a graphical user interface (GUI), and the like. 
     In one embodiment, the feeder module  104  may include feeder trays that feed print media through the printing device  100 . The print media may be any type of print media such as paper, card stock, and the like, and may have any dimensions. The feeder module  104  may feed the print media to the printing module  102 . 
     In one embodiment, the printing module  102  may print an image onto the print media. The image may be provided via a print job. The print job may be transmitted to the printing device  100  via a remote computing device or locally via a graphical user interface of the printing device  100 . For example, the print job may be selected from a memory stick that can be inserted into an interface of the printing device  100 . 
     In one embodiment, after the image is printed onto the print media, the print media may be transported to the finishing module  106 . The finishing module  106  may perform finishing functions, such as stapling, collating, stacking, and the like. 
       FIG. 2  illustrates a more detailed block diagram of the printing module  102 .  FIG. 2  illustrates a cross-sectional side view of the printing module  102 . In one embodiment, a print media  216  may be fed from the left and travel to the right through the printing module  102 . 
     In one embodiment, the printing module  102  may include a printhead  218  that includes a plurality of print nozzles  226   1  to  226   j  (also referred to herein individually as a print nozzle  226  or collectively as print nozzles  226 ). In one embodiment, the number of print nozzles  226  may correspond to a color system dispensed by the printhead  218  or to a number of individual colored inks that can be dispensed by the printhead  218 . Although a single printhead  218  is illustrated in  FIG. 2 , it should be noted that any number of printheads  218  can be deployed in the printing module  102 . 
     In one embodiment, a transport belt  212  may be used to transport the print media  216  through the printing module  102  and below the printhead  218  to receive printing fluid in accordance with a print job. In one example, the transport belt  212  may be made from a rubber material, a polymer material, a flexible plastic material, and the like. 
     In one embodiment, the transport belt  212  may be driven by a pair of drive rollers  230  and  232 . The drive rollers  230  and  232  may be rotated or powered by a respective motor  234  and  236 . For example, the motor  234  may drive the drive roller  230  and the motor  236  may drive the drive roller  232 . In another embodiment, a single drive roller and motor may be deployed with freely moving idler rollers that are not driven by a motor. 
     In one embodiment, the printing module  102  of the present disclosure may also include a positive pressure plenum system  200  (also referred to as a positive pressure plenum). The positive pressure plenum system  200  may help provide positive air flow to a bottom surface of the transport belt  212  to create an air interface. The air interface may reduce the amount of friction and wear on the transport belt  212 . For example, the air interface may prevent the bottom of the transport belt  212  from rubbing against a top surface of ridges of a plate  202 . The ridges are illustrated in  FIGS. 3 and 4 , and discussed in further details below. 
     In one embodiment, the positive pressure plenum system  200  may include a positive air flow source  204 . The positive air flow source  204  may be a fan, a blower, and the like. The positive air flow source  204  may provide air through the plate  202  and out of positive pressure openings (illustrated in  FIGS. 3 and 4  and discussed in further details below). The positive air flow is shown by arrows  208  entering the plate  202  and exiting from the plate  202  towards the bottom of the transport belt  212 . 
     In one embodiment, the positive air flow source  204  may be enclosed in a housing. The housing may ensure that the positive air flow generated by the positive air flow source  204  moves towards the plate  202  and out of the positive pressure openings of the plate, as described below in  FIGS. 3 and 4 . In some embodiments, mechanical structures such as piping, tubing, funnels, and the like, may be used to help move the positive air flow toward and through the plate  202 . 
     In one embodiment, the positive pressure plenum system  200  may also include a plurality of vacuum openings  224   1  to  224   n  (hereinafter also referred to individually as a vacuum opening  224  or collectively as vacuum openings  224 ). A negative air flow source  206  may provide a negative air flow that sucks air out of the plate  202  towards the negative air flow source  206 . The negative air flow is illustrated by arrows  210  in  FIG. 2 . 
     In one embodiment, the negative air flow source  206  may be also enclosed in a housing. The housing of the negative air flow source  206  may be separate from the housing of the positive air flow source  204 . However, both the housing of the positive air flow source  204  and the housing of the negative air flow source  206  may be coupled to the plate  202 . 
     In one embodiment, the housing of the negative air flow source  206  may be coupled to an exhaust to remove the negative air flow or vacuum generated by the negative air flow source  206 . In one embodiment, the negative air flow generated by the negative air flow source  206  may be piped back into the housing of the positive air flow source  204 . As a result, the air flow may be recycled or recirculated as part of a closed loop system. 
     In one embodiment, the negative air flow  210  may be pulled through a plurality of vacuum openings  214   1  to  214   m  (hereinafter also referred to individually as a vacuum opening  214  or collectively as vacuum openings  214 ) and the vacuum openings  224  of the plate  202 . For example, the vacuum openings  214  of the transport belt  212  may be aligned with the vacuum openings  224  of the plate  202  such that as the transport belt  212  is moved the vacuum openings  214  may temporarily align with a vacuum opening  224 . 
     The negative air flow  210  may help keep the print media  216  against the transport belt  212  as the transport belt  212  moves the print media  216  through the printing module  102 . For example, the negative air flow  210  may create a vacuum that “sucks” the print media  216  against a top surface of the transport belt  212 . Thus, the print media  216  may be held in place by the vacuum to allow the printing fluid to be accurately dispensed onto desired locations on the print media  216  in accordance with a print job. 
     In one embodiment, “positive” air flow may be considered to be air flow that is being added to the plate  202 . For example, the positive air flow source  204  may generate air flow that is inserted into the plate  202 . In one embodiment, “negative” air flow may be considered to be air flow that is being removed from the plate  202 . 
     In one embodiment, the printing module  102  may also include a controller  238  and a memory  240 . The controller  238  may be communicatively coupled to the positive air flow source  204 , the negative air flow source  206 , the motor  234 , the motor  236 , and the memory  240 . In one embodiment, the controller  238  may also be communicatively coupled to a negative air flow sensor  220 , a positive air flow sensor  222 , and a sensor  228 . 
     In one embodiment, the controller  238  may control operation of the motor  234  and the motor  236  when the sensor  228  detects the print media  216  entering the printing module  102 . In another embodiment, the sensor  228  may be located upstream of the transport belt  212  to detect when the print media  216  is about to arrive on the transport belt  212 . The sensor  228  may be part of a registration system that is used to properly orient the print media  216  (e.g., adjusting a skew, lateral position, and the like) before the print media  216  is placed onto the transport belt  212 . The sensor  228  may be any type of sensor that can detect the print media  212 . 
     The controller  238  may begin to operate the motor  234  and the motor  236  to rotate the drive rollers  230  and  232 , respectively. The drive rollers  230  and  232  may then begin to rotate the transport belt  212 . In addition, the controller  238  may begin operation of the positive air flow source  204  and the negative air flow source  206 . 
     In one embodiment, the controller  238  may operate the positive air flow source  204  and the negative air flow source  206  such that a desired amount of positive air flow and a desired amount of negative air flow is generated. The amount of positive air flow may be measured by the positive air flow sensor  222 . The controller  238  may receive the amount of positive air flow measured by the positive air flow sensor  222  and adjust the amount (e.g., increase or decrease) of positive air flow generated by the positive air flow source  204 . Similarly, the controller  238  may receive the amount of negative air flow measured by the negative air flow sensor  220  and adjust the amount (e.g., increase or decrease) of negative air flow generated by the negative air flow source  206 . 
     In one embodiment, the desired amounts of air flow may be stored in the memory  240 . For example, the controller  238  may compare the measured amount of positive air flow and the measured amount of negative air flow and compare the amounts to the desired amounts stored in the memory  240 . Based on the comparison, the controller  238  may adjust the amount of air flow generated by the positive air flow source  204  and the negative air flow source  206 . 
     In one embodiment, the desired amount of negative air flow may be greater than the desired amount of positive air flow. In one embodiment, the memory  240  may store a desired difference threshold that is a difference between the amount negative air flow and the amount of positive air flow. The values of the threshold may be a function of process parameters of a particular print job, operating efficiency of the transport belt  212  at a given time, and the like. For example, for larger print media  216  the difference may be lower as the weight of the print media  216  may require less negative air flow to hold the print media  216  against the transport belt  212 . However, more positive air flow may be used to create the air interface due to the added weight of the larger print media  216 . However, the amount of negative air flow would still be greater than the amount of positive air flow. 
     In another example, for smaller print media  216 , the difference may be larger as the lighter weight of the print media  216  may require less negative air flow to hold the print media  216  against the transport belt  212 . However, less positive air flow may be used to create the air interface due to the lower weight associated with the smaller print media  216 . Again, the amount of negative air flow would be greater than the amount of positive air flow. 
     In one example, as the printing fluid falls through the openings of the transport belt  212  between sheets of the print media  216  onto a top surface of the plate  202 , the transport belt  212  may experience more friction as the transport belt  212  moves. Thus, the amount of positive air flow may be increased by the controller  238  to create the air interface between the top surface of the plate  202  and a bottom surface of the transport belt  212 . However, to ensure the negative air flow is greater than the positive air flow, the amount of negative air flow may also be adjusted accordingly. 
       FIG. 3  illustrates an isometric cross-sectional view of the plate  202 .  FIG. 3  provides a better illustration of the structural features of the plate  202  in the positive pressure plenum system  200  of the present disclosure. The plate  202  may be fabricated from a metal, alloy, plastic, glass, and the like. 
     In one embodiment, the plate  202  may include ridges  250 . The plurality of ridges  250  may have a raised surface. The top surface of the ridges  250  may contact the bottom surface of the transport belt  212 . The plurality of ridges may run in parallel and be spaced apart across a top surface of the plate  202 . In one embodiment, each one of the plurality of ridges may have the same dimensions. 
     In one embodiment, each one of the plurality of ridges  250  may include a plurality of positive pressure openings  252 . The positive pressure openings  252  may be spaced apart along the top surface of the plurality of ridges  250 . In one embodiment, the minimum amount of positive air flow that is generated by the positive air flow source  204  may be enough positive air flow to allow the positive air flow to escape out of the positive pressure openings  252 . 
     Any number of positive pressure openings  252  may be deployed in each one of the plurality of ridges  250 . Each one of the plurality of ridges  250  may have the same number of positive pressure openings  252  or may have a different number of positive pressure openings  252 . 
     As illustrated in  FIG. 4 , and discussed in further details below, the positive pressure openings  252  are located such that the positive pressure openings  252  do not align with the vacuum openings  214  of the transport belt  212 . In other words, the positive pressure openings  252  are positioned to be continuously against a solid portion of the transport belt  212  as the transport belt  212  moves around the positive pressure plenum system  200 . 
     In one embodiment, each one of the plurality of ridges  250  may have a hollow opening, a hollow ridge, or a tunnel  256 . One end of the plurality of ridges  250  may be open to allow the positive air flow generated by the positive air flow source  204  to enter the tunnels  256 . The opposite end of the plurality of ridges  250  may be closed to prevent the positive air flow from running straight through the plurality of ridges  250 . In other words, the tunnels  256  may be formed across the entire distance of the ridges  250  up to the closed end. Thus, the positive air flow is forced out of the positive pressure openings  252  in a direction that is towards the bottom surface of the transport belt  212 . 
     Said another way, the positive air flow may enter the plate  202  laterally through the tunnels  256  of each one of the plurality of ridges  250 . However, the positive air flow may exit through the positive pressure openings  252  in a direction that is perpendicular to the lateral flow of the positive air flow that enters the tunnels  256 . 
     In one embodiment, the plurality of ridges  250  may be spaced apart, as noted above. In one embodiment, a depressed region or trough  254  may be located between each one of the plurality of ridges  250 . In other words, the plate  202  may include a plurality of troughs  254 , wherein each one of the plurality of troughs  254  is located between a pair of the ridges  250 . Said another way, the top surface of the plate  202  may comprise an alternating series of a ridge  250  and a trough  254 . The plurality of troughs  254  may have the same dimensions; however, the dimensions of the plurality of troughs  254  may be different than the dimensions of the plurality of ridges  250 . 
     In one embodiment, the plurality of troughs  254  may include a plurality of vacuum openings  224 . Each one of the plurality of troughs  254  may have any number of vacuum openings  224 . As can be seen in  FIG. 3 , the vacuum openings  224  may be cut through the entire thickness of the troughs  254 . In other words, the vacuum openings  224  may be cut from a bottom surface of the plate  202  through the entire thickness of the plate  202  and to the top surface of the trough  254 . 
     In addition, the vacuum openings  224  may be cut such that the vacuum openings  224  do not communicate with the tunnels  256  and the positive pressure openings  252 . In other words, the vacuum openings  224  may be isolated from the tunnels  256  and the positive pressure openings  252 . Said yet another way, the positive air flow that enters the tunnel  256  must exit through the positive pressure openings  252  and cannot enter the vacuum openings  224  without first exiting through the positive pressure openings  252 . 
     In one embodiment, a diameter  262  of the vacuum openings  224  may be larger than a diameter  260  of the positive pressure openings  252 . The larger size of the diameter  262  of the vacuum openings  224  may help to ensure that the amount of negative air flow through the vacuum openings  224  is greater than the positive air flow through the positive pressure openings  252 , as noted above. In one example, the diameter  260  of the positive pressure openings  252  may be approximately 2 millimeters (mm) and the diameter  262  of the vacuum openings  224  may be approximately 3 mm. 
     In one embodiment, the 2 mm diameter and the 3 mm diameter is sufficient to generate a desired amount of positive air flow to create an air interface between the plurality of ridges  250  and a bottom surface of the transport belt  212 . The 2 mm diameter and the 3 mm diameter are also sufficient to generate a desired amount of negative air flow to create a vacuum to hold the print media  216  against the top surface of the transport belt  212 . However, it should be noted that other dimensions for the diameter  260  and  262  may also be deployed to achieve the desired amount of positive air flow and the desired amount of negative air flow. 
       FIG. 4  illustrates a top view of an example of the transport belt  212  and the plate  202 .  FIG. 4  illustrates an example where the process direction is shown by an arrow  402 . For example, the print media  216  may enter from the left and be transported to the right out of the printing module  102 . 
     The plate  202  is illustrated in phantom lines or dashed lines below the transport belt  212 . In one embodiment, the plate  202  may have a width “w” and a length “I”. The plurality of ridges  250  and the plurality of troughs  254  may run across a length of the plate  202 , as shown in dashed lines being hidden by the transport belt  212 . The plurality of ridges  250  and the plurality of troughs  254  may be alternated across a width of the plate  202 . 
     As noted above, the transport belt  212  may be positioned such that the vacuum openings  214  of the transport belt  212  are aligned with the vacuum openings  224  (shown in dashed lines below the transport belt  212 ) in the plurality of troughs  254  of the plate  202 . In one example, the line of vacuum openings  214  of the transport belt  212  may travel along the length of the respective trough  254  and respective vacuum openings  224 . As a result, the vacuum may be applied continuously to the print media  216  on the transport belt  212 . Although  FIG. 4  illustrates a diameter of the vacuum openings  224  being larger than the vacuum openings  214 , it should be noted that in one embodiment the vacuum openings  214  and the vacuum openings  224  may have approximately the same diameter. 
     In one embodiment, “aligned” may mean that the line of vacuum openings  214  lies on the same line of vacuum openings  224 . As a result, as the transport belt  212  is moved from left to right, the vacuum openings  214  are positioned directly over a respective trough  254  and respective vacuum openings  224 . As a result, the negative air flow may suck the print media  216  against the top surface of the transport belt  212  as the negative air flow is pulled through vacuum openings  214  and  224 . 
     Also as noted above, the positive pressure openings  252  (shown in dashed lines below the transport belt  212 ) may be positioned such that they are always below a solid portion of the transport belt  212 . In other words, the vacuum openings  214  are never aligned or positioned over the positive pressure openings  252  as the transport belt  212  is moved in the process direction  402 . 
     The location of the positive pressure openings  252  relative to the solid portions of the transport belt  212  (e.g., areas without the vacuum openings  214 ) may prevent the positive air flow from counteracting the vacuum applied by the negative air flow, as described above. In addition, the positive air flow may push against the bottom surface of the transport belt  212  to create the air interface, as described above. The air interface may allow the transport belt to “hover” over the top surface of the plate  202  or the plurality of ridges  250  as the transport belt  212  moves in the process direction  402 . Thus, the air interface may reduce the overall friction and wear on the transport belt  212  as the transport belt  212  is moved. 
       FIG. 5  illustrates another example of a positive pressure plenum system  500 . For example, although  FIG. 2  illustrates the positive pressure plenum system  200  with the positive air flow source  204  and the negative air flow source  206  in a side-by-side configuration, other configurations are also possible. For example,  FIG. 5  illustrates a configuration where a positive air flow source  504  is located below a negative air flow source  506 . The top and bottom configuration illustrated in  FIG. 5  may be deployed where less room is available across a length of the printing module  102 . 
     The positive air flow source  504  may provide a positive air flow (as shown by an arrow  508 ) up and laterally through the plate  502 . The plate  502  may be similar to the plate  202  and be comprised of a plurality of ridges that contain tunnels and positive pressure openings along a top surface of the plurality of ridges. The positive air flow may exit out of the positive pressure openings towards a bottom surface of a transport belt (e.g., the transport belt  212 ). In some embodiments, a tubing, funnels, piping, and other mechanical features (not shown) may be used to channel the positive air flow generated by the positive air source  504  to the plate  502 . 
     In one embodiment, the plate  502  may also include a plurality of troughs similar to the plate  202  that include a plurality of vacuum openings  524   1  to  524   n  (also referred to herein individually as a vacuum opening  524  or collectively as vacuum openings  524 ) along the troughs. The troughs and the ridges may be arranged as described above with respect to the plate  202 . 
     In one embodiment, the negative air flow source  506  may create a negative air flow or suck air down towards the negative air flow source  506 , as shown by arrows  510 . The negative air flow may be pulled through the vacuum openings  524  in the plate  502  to create a vacuum. The vacuum may hold the print media  216  against a top surface of the transport belt  212 , as described above. 
     Similar to the positive pressure plenum system  200 , the positive pressure plenum system  500  may also be controlled by the controller  238  to generate a desired amount of positive air flow and a desired amount of negative air flow. It should be noted that  FIGS. 2 and 5  illustrate examples of possible configurations of the positive air flow source  504  the negative air flow source  506  and that other configurations are possible and within the scope of the present disclosure. 
       FIG. 6  illustrates a flowchart of an example method  600  for controlling a position of a print media in a registration system. In one embodiment, one or more steps or operations of the method  600  may be performed by the printing module  102  of the printing device  100 , or a computer/processor that controls operation of the printing module  102  as illustrated in  FIG. 7  and discussed below. 
     At block  602 , the method  600  begins. At block  604 , the method  600  detects a print media entering the printing module to receive a print job. For example, a sensor or a registration system may detect a lead edge of the print media entering the printing module. In response to detecting the print media, the transport belt may be activated and begin moving. The transport belt may receive the print media and begin transporting the print media through the printing module and below one or more printheads to receive printing fluid in accordance with a print job. 
     At block  606 , the method  600  provides a vacuum, in response to the print media that is detected, via a vacuum air source in a positive pressure plenum that provides a negative air flow through a plurality of vacuum openings of a transport belt to hold the print media against the transport belt as the transport belt moves the print media below a plurality printheads. In one embodiment, the negative air flow may be sucked through a plurality of vacuum openings of the positive pressure plenum that are located in a plurality of depressed spaces or troughs located between a plurality of hollow ridges. The depressed spaces or troughs and the plurality of hollow ridges may be arranged as part of a plate, as described above and illustrated in  FIGS. 3 and 4 . 
     In one embodiment, the plurality of vacuum openings of the positive pressure plenum may be aligned with the plurality of vacuum openings of the transport belt as illustrated in  FIG. 4 . As a result, as the transport belt moves, the vacuum holes in the transport belt may travel over the depressed spaces or troughs and the respective vacuum holes in the positive pressure plenum. The negative air flow may then be pulled through the vacuum holes to hold the print media against the transport belt. 
     At block  608 , the method  600  provides a positive air flow, in response to the print media that is detected, through the positive pressure plenum via a positive air flow source to provide an air interface between a bottom surface of the transport belt and a top surface of the positive pressure plenum as the transport belt moves across the top surface of the positive pressure plenum. In one embodiment, the air interface created by the positive air flow may help reduce friction and wear on the transport belt while the transport belt is moving. 
     In one embodiment, the amount of positive air flow that is generated may be less than the amount of negative air flow that is generated to ensure that there is sufficient vacuum to hold the print media against the transport belt. In one embodiment, the amount of positive air flow that is generated may be sufficient to allow the positive air flow to escape from the positive pressure plenum and out between the positive pressure plenum and a bottom surface of the transport belt. 
     In one embodiment, a controller may control and adjust the amount of negative air flow that is generated and the amount of positive air flow that is generated. For example, the method  600  may measure the amount of negative air flow via a vacuum (or negative air flow) sensor and measure the amount of positive air flow via a positive air flow sensor. The controller may then compare the amount of negative air flow that is measured and the amount of positive air flow that is measured to desired amounts or to a desired difference threshold. Based on the comparison, the controller may adjust the amount of negative air flow and/or the amount of positive air flow that is generated. 
     In one embodiment, the desired difference threshold may be based on printing parameters such as a type of print media that is being used (e.g., the size and the weight of the print media), a speed of the transport belt (e.g., the speed may change as ink is spilled onto a top surface of the ridges or plate of the positive pressure plenum), and the like. The difference threshold may be a difference between the amount of negative air flow sufficient to hold the print media and counteract the positive air flow and the amount of positive air flow sufficient to create the air interface between the top surface of the plate of the positive pressure plenum and a bottom surface of the transport belt. For example, the amount of positive air flow may be an amount sufficient to allow the positive air flow to escape between a bottom surface of the transport belt and the positive pressure openings of the positive pressure plenum. 
     The method  600  may be continuously repeated for each print media that is printed through the printing module  102 . At block  610 , the method  600  ends. 
     It should be noted that the blocks in  FIG. 6  that recite a determining operation or involve a decision do not necessarily require that both branches of the determining operation be practiced. In other words, one of the branches of the determining operation can be deemed as an optional step. In addition, one or more steps, blocks, functions or operations of the above described method  600  may comprise optional steps, or can be combined, separated, and/or performed in a different order from that described above, without departing from the example embodiments of the present disclosure. 
       FIG. 7  depicts a high-level block diagram of a computer that is dedicated to perform the functions described herein. As depicted in  FIG. 7 , the computer  700  comprises one or more hardware processor elements  702  (e.g., a central processing unit (CPU), a microprocessor, or a multi-core processor), a memory  704 , e.g., random access memory (RAM) and/or read only memory (ROM), a module  705  for operating a printing module, and various input/output devices  706  (e.g., storage devices, including but not limited to, a tape drive, a floppy drive, a hard disk drive or a compact disk drive, a receiver, a transmitter, a speaker, a display, a speech synthesizer, an output port, an input port and a user input device (such as a keyboard, a keypad, a mouse, a microphone and the like)). Although only one processor element is shown, it should be noted that the computer may employ a plurality of processor elements. 
     It should be noted that the present disclosure can be implemented in software and/or in a combination of software and hardware deployed on a hardware device, a computer or any other hardware equivalents (e.g., the printing device  100 ). For example, computer readable instructions pertaining to the method(s) discussed above can be used to configure a hardware processor to perform the steps, functions and/or operations of the above disclosed methods. In one embodiment, instructions and data for the present module or process  705  for operating a printing module (e.g., a software program comprising computer-executable instructions) can be loaded into memory  704  and executed by hardware processor element  702  to implement the steps, functions or operations as discussed above in connection with the example method  600 . Furthermore, when a hardware processor executes instructions to perform “operations,” this could include the hardware processor performing the operations directly and/or facilitating, directing, or cooperating with another hardware device or component (e.g., a co-processor and the like) to perform the operations. 
     The processor executing the computer readable or software instructions relating to the above described method(s) can be perceived as a programmed processor or a specialized processor. As such, the present module  705  for operating a printing module (including associated data structures) of the present disclosure can be stored on a tangible or physical (broadly non-transitory) computer-readable storage device or medium, e.g., volatile memory, non-volatile memory, ROM memory, RAM memory, magnetic or optical drive, device or diskette and the like. More specifically, the computer-readable storage device may comprise any physical devices that provide the ability to store information such as data and/or instructions to be accessed by a processor or a computing device such as a computer or an application server. 
     It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.