Patent Publication Number: US-10328724-B2

Title: Printing system with a printing fluid collector

Description:
BACKGROUND 
     Printing systems may be arranged to transport a print medium along a media path and allow for a printing fluid to be deposited onto the print medium. A media transport system may be used to transport the print medium along the media path, it may comprise a set of driven rollers or a belt. Printing fluid may be deposited onto the print medium using fluid ejection technologies. A variety of materials may be used as print media in such printing systems, for example papers, cards, plastics and textiles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features of the present disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example only, features of the present disclosure, and wherein: 
         FIG. 1  is a schematic illustration of a printing system according to an example; 
         FIG. 2  is a schematic illustration showing a printing system according to an example; 
         FIG. 3A  is a schematic illustration showing a printing system according to an example; 
         FIG. 3B  is a schematic illustration showing the printing system of  FIG. 3A  with an installed printing fluid collector; 
         FIG. 4  is a schematic illustration showing a removable printing fluid collector according to an example; 
         FIG. 5  is a flow diagram showing a method of operating a printing system according to an example; 
         FIG. 6  is a flow diagram showing a method of operating a printing system according to an example; 
         FIG. 7  is a flow diagram showing a method of operating a printing system according to an example; and 
         FIG. 8  is a schematic illustration showing a processor and a computer readable storage medium with instructions stored thereon according to an example. 
     
    
    
     DETAILED DESCRIPTION 
     During a printing operation, printing fluid deposited onto a print medium may penetrate the print medium to a degree dependent on the print medium&#39;s porosity. When a print medium having a sufficiently high porosity is used, printing fluid may permeate the print medium completely, leading to a leakage of printing fluid. This leakage may negatively affect the printing process. In one case, the media path may become stained. For example, a platen above a vacuum generator for the media path may become stained with ejected ink. This may result in the staining of an underside of print media in subsequent printing operations. Another issue is that a printer vacuum system, which may involve the flow of air through holes on a component of the media path in order to retain the print medium on the media path during the printing operation, may malfunction due to the blockage of such holes with printing fluid. These holes may comprise holes in a platen or belt. Excess printing fluid may also clog mechanical components of the printing system and affect electronic circuits within the printing system. These and other leakage-related faults may involve cleaning, servicing or replacement of components to be carried out, resulting in expense and printing system downtime. Examples of particularly porous materials commonly used as print media, which may affect the printing process as described, include textiles and fabrics. The term “porous material” and variants thereof are henceforth used to mean materials having a sufficiently high porosity that printing fluid may typically be able to traverse a medium which comprises the material. A “printer” or “printing system” as described herein may comprise any device suitable for performing an additive manufacturing process, which may include but not be limited to systems for additive manufacturing in two-dimensions and/or three-dimensions. 
     In order to reduce the effect of printing fluid staining or impeding the media path after permeating a porous medium, a printing fluid collector may be installed in relation to the media path. The printing fluid collector may be arranged to collect excess printing fluid that permeates the print medium. For example, a printing fluid collector may be arranged, in use, to be underneath the print medium, e.g. located below the media path. In certain cases a printing fluid collector may replace a platen of the media path that is installed above a vacuum generator for the media path. 
     Certain examples described herein allow for a determination of a porosity of a print target in a printing system. A signal relating to a state of a printing fluid collector is then generated according to the determined porosity. For example, this signal may prevent a print operation if a suitable printing fluid collector is not installed to reduce the issues of printing fluid permeation described above. The printing fluid collector may be removably installed in the printing system via a collector coupling, which may be arranged to mount the printing fluid collector to receive printing fluid. In certain cases, a presence of a printing fluid collector may be determined with one or more sensors associated with the collector coupling. Certain examples determine the porosity based on a pressure measurement obtained from a vacuum system located on a media path of the printing system when the print target is present on the media path. The pressure measurement may be compared to at least one predefined pressure range in order to indicate a state of the printing fluid collector. In certain examples, a predefined pressure range may correspond to an obtained width of the print target. Certain examples allow for the obtaining of a signal indicative of whether the printing fluid collector is installed in the printing system. In one case, at least one switch may be arranged in relation to a printing fluid collector coupling such that, if the printing fluid collector is installed in the printing system, the at least one switch causes the generation of said signal. If it is determined that the printing fluid collector is not installed, a signal may be generated to inhibit a printing operation. 
     Certain examples described herein increase printing system robustness when handling a variety of print media. This may be achieved by preventing a printing operation when it is determined that a porous medium is present on the media path and a suitable printing fluid collector is not installed. By preventing excess printing fluid ejection from leaking onto or into the media path, vacuum system or other printer components, e.g. following permeation or penetration of a porous print medium, printing system downtime may be reduced and there may a reduced need for servicing, replacement and cleaning. 
       FIG. 1  shows a printing system  100  according to an example. The printing system  100  comprises a porosity determiner  110  connectively coupled to a signal generator  120 . The porosity determiner  110  is configured to determine a porosity of a print medium in the printing system  100 . The signal generator is configured to generate a signal  130  relating to a state of a printing fluid collector based on the determined porosity, e.g. the output of the porosity determiner  110  as supplied to the signal generator  120 . In one case, the signal generator  120  may be configured to obtain a signal indicative of a state of a printing fluid collector and, if it is determined from said signal that the printing fluid collector is not present and the print medium is deemed porous, generate a signal  130  indicating that the printing fluid collector be installed. This may involve interrupting a print operation until the signal indicative of a state of a printing fluid collector indicates that the printing fluid collector is present. 
     The porosity determiner  110  may, according to one example, comprise a pressure sensor arranged to measure a pressure in a vacuum system of the printing system. In another example, the porosity determiner  110  comprises control electronics arranged to compare an obtained pressure measurement with at least one predefined pressure range. In a further example, the porosity determiner  110  comprises a pressure sensor arranged to measure a pressure a vacuum system of the printing system and control electronics arranged to compare an obtained pressure measurement with at least one predefined pressure range and determine a porosity of the print medium based on the comparison. 
     In one example, the porosity of the print medium may be a measure of the degree to which a fluid may permeate the print medium during a given time period. In another example, the porosity of the print medium may be a measure of the time taken for a fluid to pass through a given width of medium. In a further example, the porosity of the print medium may be a measure of a change in pressure of a fluid, for example air, passing through the medium. The porosity of the print medium may, according to a still further example, be a measure of a void fraction of the material used as the print medium. The signal  130  may, according to one example, be used to notify a user regarding the state of the printing fluid collector via an interface of the printing system. The notification may comprise text output, audio output, graphical output or any combination thereof. The notification may inform the user that a suitable printing fluid collector needs to be installed in the printing system, e.g. if it is further detected that the printing fluid collector is not installed. In another example, the signal  130  may be used to determine whether a suitable printing fluid collector is presently installed in the printing system. In a further example, the signal  130  may be used to prevent a printing operation upon the print medium. 
     The printing fluid collector described herein may also be known, for example, as a gutter, a drip tray, an ink collector or a waste ink collection tray. The terms “print medium”, “medium”, “print target”, “printing substrate” and “substrate” are used herein interchangeably. The term “printing fluid” as used herein refers to any fluid suitable for printing, including, amongst others an ink, a gloss, a varnish and a coating. In certain cases multiple printing fluid collectors may be available for installation. In such cases a particular printing fluid collector may be associated with a particular range of determined pressures and/or porosities. For example, highly porous printing substrates may require a printing fluid collector with a first filter configuration and/or a first fluid capacity and semi-porous printing substrates may require a printing fluid collector with a second filter configuration and/or a second fluid capacity, e.g. where the first fluid capacity is greater than the second fluid capacity. 
       FIG. 2  shows certain components of a printing system  200  according to an example. The components shown are those that may interact with the porosity determiner  110  and the signal generator  120  of  FIG. 1 . The printing system may comprise further components, however these are omitted in the present description for ease of explanation. In the example of  FIG. 2 , four components of the printing system  200  are shown: a fluid deposit system  210 , a media transport system  220 , a vacuum system  230  and a control system  240 . 
     The fluid deposit system  210  is used to deposit printing fluid onto a print medium in the printing system  200 . The fluid deposit system  210  may comprise an inkjet deposit system. The print medium is transported along a media path by the media transport system  220 . The media transport system  220  may comprise an arrangement of one or more belts and/or one or more rollers to transport the print medium. These belts and/or rollers may be driven by a drive mechanism, e.g. one or more electromechanical motors. In the printing system  200  of  FIG. 2 , the print medium is retained on the media path during a printing operation by the use of a vacuum system  230 . The vacuum system  230  is arranged to generate a vacuum in relation to the media path, e.g. below one or more belts and/or one or more rollers of the media transport system  220 . If the media transport system  220  comprises one or more belts or platens then a force may be applied to a print medium on the media path, e.g. downwards onto the one or more belts and/or platens, by way of an air flow through apertures in said one or more belts and/or platens, the air flow resulting from the vacuum generated by the vacuum system  230 . The control system  240  is connectively coupled to the fluid deposit system  210 , media transport system  220  and vacuum system  230 . In  FIG. 2 , the control system  240  controls the operation of the fluid deposit system  210 , the media transport system  220  and the vacuum system  230 . Although in this example one control system  240  is used to control the three components, in other examples, a set of separate control components, e.g. controller electronics, may be used to individually control the three components. In general, any arrangement that enables the control functionality described herein may be used.  FIG. 2  is provided to help explain an example context for operation of the apparatus of  FIG. 1  and the method of  FIG. 5  and should not be seen as limiting. 
     In one case, one or both of the porosity determiner  110  and signal generator  120  of  FIG. 1  may be implemented as part of the control system  240 . In other cases, one or both the porosity determiner  110  and signal generator  120  of  FIG. 1  may be implemented as part of the vacuum system  230 . In one example, the control system  240  may be configured to receive a pressure measurement from the vacuum system  230 , to determine a porosity based on the received pressure measurement, and to generate a signal relating to a state of a printing fluid collector based on the determined porosity. In another example, the control system  240  may be configured to receive a signal from the vacuum system  230  relating to a state of a printing fluid collector, and to generate a notification to a user via an interface of the printing system. In a further example, the control system  240  may be configured to prevent a printing operation, based on receiving a signal indicating that a suitable printing fluid collector is not installed in the printing device, by sending signals to one or both of the fluid deposit system  210  and the media transport system  220 . 
       FIGS. 3A and 3B  show a printing system  300  in more detail according to an example. A print head  305  deposits printing fluid onto a print medium  310 . The print medium  310  is transported (as shown by the white arrows) along a media path  315 . In  FIGS. 3A and 3B  the print medium  310  is transported horizontally from the right hand side of the Figure to the left hand side of the Figure, although actual implementations may vary from the schematic example illustrations. A vacuum system  320  is arranged to provide a fluid flow (as shown by the black arrows) through the media path  315 , so as to apply a force to the print medium  310  to retain the print medium  310  on the media path  315  during a print operation. In one case, one or more belts and/or platens may be located above the vacuum system  320  to support the print medium  320  as part of the media path  315 . In  FIGS. 3A and 3B  the fluid flow is shown operating vertically, e.g. from the top of the Figure to the bottom of the Figure, although again actual implementations may vary from the schematic example illustrations. In one case, the fluid flow may comprise an air flow. The vacuum system  320  comprises at least one vacuum generator  330  arranged below the media path  315  and a vacuum chamber  335  arranged in fluid communication with the at least one vacuum generator  330 . At least one pressure sensor  340  is arranged in the vacuum chamber  335  to provide a pressure measurement. A collector coupling  325  is arranged to removably couple a printing fluid collector  345  to the printing system  300 .  FIG. 3A  shows the printing system  300  without the printing fluid collector  345  coupled to it, and  FIG. 3B  shows the printing system  300  with the printing fluid collector  345  coupled to it. The collector coupling  325  is arranged to mount the printing fluid collector  345  to receive printing fluid during a print operation. In  FIG. 3A  the collector coupling  325  is arranged above the vacuum system  320  below the print head  305 . In other examples, the collector coupling  325  may be arranged within the vacuum system  320 . In one case, one or more mechanical components, e.g. platens, roller or belts, may be installed in place of a printing fluid collector. In certain examples, these may be coupled to the collector coupling  325 ; in other examples they may have separate mechanical couplings. 
     The print head  305  may comprise a plurality of nozzles for depositing printing fluid onto the print medium. The configuration of the print head may vary based on the type of printing system and the type of printing fluid used. The media path  315  may comprise a platen. In one case, at least a portion of the media path below the print head  305  may comprise a platen having a plurality of holes to allow the fluid flow provided by the vacuum system through the media path. In certain examples, the platen may be driven, e.g. convey the print medium along the media path; in other examples the platen may be static, e.g. driven components of the media transport system may be located on at least one side of the platen. The at least one vacuum generator  330  may comprise one or more of: at least one vacuum pump, at least one vacuum ejector, at least one vacuum fan; and at least one vacuum blower. The at least one vacuum generator  330  may be driven at a constant power during a printing operation. In another case, the at least one vacuum generator may be driven at a varying power during a printing operation. The vacuum chamber  335  may, according to various examples, be a chamber within which the pressure is lower than the atmospheric pressure. The pressure within the vacuum chamber may be lowered by the driving of the at least one vacuum generator  330 . 
     The collector coupling  325  may, according to one example, be a mechanical coupling arranged to receive a printing fluid collector  345  as shown in  FIG. 3B  and retain it securely through the use of one or more of grooves, holes, hinges, latches, friction and other mechanical and/or gravitational mechanisms. In another example, the collector coupling  325  may retain the printing fluid collector  345  via magnetic attraction. In one case, an operator of the printing system may be instructed to manually couple the printing fluid collector  345  to the collector coupling  325 . The collector coupling  325  may, according to one example, be arranged relative to at least one switch for determining whether the printing fluid collector is coupled to the printing system. In one case, the printing fluid collector  345 , when installed as shown in  FIG. 36 , may replace a corresponding component of the media path  315  such as a platen. 
     The at least one pressure sensor  340  may comprise at least one differential pressure sensor according to one example. In another example, the at least one pressure sensor may comprise at least one gauge pressure sensor. In a further example, the at least one pressure sensor may comprise at least one vacuum pressure sensor. Other types of pressure sensor may be used according to various examples. The at least one pressure sensor may produce an electrical signal based on the pressure imposed upon it according to various examples. 
       FIG. 4  shows a removable printing fluid collector  400  according to an example. The removable printing fluid collector  400  comprises an elongate collector body  410  and at least one foam filter  420 . The elongate collector body  410  is arranged to extend across a width of a media path of a printing system and to receive ejected printing fluid, e.g. printing fluid that is ejected from nozzles of a print head onto a print medium on a media path and that permeates (e.g. passes through at least in part) the print medium. The at least one foam filter  420  is arranged within the elongate collector body  410  for absorption of the received printing fluid. In one case an upper and lower foam filter may be provided, the lower foam filter being located at the bottom of the elongate collector body  410  and the upper foam filter being located within a top opening of the elongate collector body  410 . In this case each foam filter may have a different composition to provide for differentiated printing fluid absorption. The at least one foam filter  420 , e.g. either or both of the upper and lower filters, may comprise apertures to enable a fluid flow through the printing fluid collector  400 . In certain cases at least one foam filter  420  may allow a fluid flow so as to maintain the application of the vacuum generated by the vacuum system  320 . 
     When it is coupled to the printing system  300  via the collector coupling  325 , the removable printing fluid collector  400  may, according to one example, be arranged within a set of media transport system components. In one example, the removable printing fluid collector  400  may be arranged between two rollers of the media transport system. In certain examples, the removable printing fluid collector  400  may be arranged within the vacuum system  320  of the printing system, although in the example shown in  FIG. 3B  it is arranged externally to the vacuum system  320 . As the vacuum system  320  is configured to provide a fluid flow through the media path and apply a force to the print medium to retain the print medium on the media path during a print operation, it follows that printing fluid permeating a porous medium may be ejected towards the vacuum system, informing a position of the printing fluid collector. The at least one foam filter  420  may, according to one example, be replaced when saturated with printing fluid. In another example, the at least one foam filter may be reusable after saturation with printing fluid, e.g. by washing and/or compressing said filter. 
     The examples of  FIGS. 1, 2, 3A, 3B and 4  show components of a printing system that enable a porosity or permeability of a print medium to be determined and used to control the printing system with relation to the installation of a suitable printing fluid collector. A number of example methods are described below that may make use of the components of one or more of these examples. 
       FIG. 5  shows a method  500  of operating a printing system according to an example. The printing system may comprise one of printing systems  100 ,  200  and  300  as previously described. At block  510 , a pressure measurement is obtained from a vacuum system of the printing system when a print medium is present on a media path of the printing system. At block  520 , the pressure measurement obtained at block  510  is compared to at least one predefined pressure range. At block  530 , a state of a printing fluid collector is indicated via the printing system, based on the comparison carried out at block  520 . This may comprise an operational state of the printing fluid collector, e.g. that a printing fluid collector of a particular type needs to be installed. 
     In one example, the method  500  may be performed by the porosity determiner  110 . In another example, block  510  may be performed by the at least one pressure sensor  340 , and blocks  520  and  530  may be performed by the porosity determiner  110 . In a further example, block  510  may be performed by the at least one pressure sensor  340 , block  520  may be performed by the porosity determiner  110  and block  530  may be performed by the signal generator  120 . The indication of a state of a printing fluid collector at block  530  may, according to one example, comprise a notification to a user, via an interface, that the printing fluid collector is not presently coupled to the printing system. In another example, the indication at block  530  may comprise a request for a user to couple the fluid collector to the printing system. In a further example, the indication at block  530  may comprise a request for a user to couple the fluid collector to the printing system if it is determined that the printing fluid collector is not presently coupled to the printing system. According to a still further example, the indication at block  530  may comprise the inhibition of a print operation until it is determined that a suitable printing fluid collector is coupled to the printing system. 
       FIG. 6  shows a method  600  of operating a printing system according to a further example. The method  600  may comprise one possible implementation of the method  500 . At block  610 , a pressure measurement is obtained from a vacuum system of a printing system when a print medium is present on a media path of the printing system. The printing system may comprise one of printing systems  100 ,  200  and  300  as previously described. At block  620 , a width of the print medium is obtained. At block  630 , at least one predefined pressure range, corresponding to the width obtained at block  620 , is retrieved. The width of the print medium may determine the portion of the media path covered by the print medium, and consequently the number of exposed holes in the media path which allow fluid flow provided by the vacuum system. Therefore a vacuum generator may be operated to apply a defined pressure for a given width of print medium. At block  640 , the pressure measurement obtained at block  610  is compared to the at least one predefined pressure range retrieved at block  630 . Porosity data indicative of the print medium not being porous is generated when the pressure measurement is within a first pressure range, and porosity data indicative of the print medium being porous is generated when the pressure measurement is within a second pressure range. For example, a binary parameter indicative of porosity may be set to true if the print medium is determined to be porous. At block  650 , a state of a printing fluid collector is indicated. Responsive to the porosity data indicating that the print medium is porous, a determination is made whether the printing fluid collector is coupled to the printing system. At block  650 , responsive to the printing fluid collector not being coupled to the printing system a print operation may be prevented and/or a notification may be sent and/or displayed to a user. 
     In one case, obtaining the width of the print medium at block  620  may comprise generating a request, via an interface, for a user to input the correct width of the print medium. In another case, the obtaining the width of the print medium may comprise a media width detector automatically detecting the width of the print medium. In another case, the width of the print medium may be retrieved from a media definition the for a currently used print medium. The retrieving, at block  630 , of the at least one predefined pressure range corresponding to the obtained width may, according to certain examples, comprise retrieving values corresponding to predefined pressure ranges from a lookup table stored within a computer-readable memory. 
     In at least one example, the at least one predefined pressure range may comprise two predefined pressure ranges. In certain other examples, the at least one predefined pressure range may comprise one predefined pressure range and one additional pressure range that is calculated based the predefined pressure range. The additional pressure range may, according to one example, comprise pressure values that do not fall within the predefined pressure range. In a further example, the additional pressure range may comprise pressure values that are greater than the upper boundary of the predefined pressure range. In a still further example, the additional pressure range may comprise pressure values that are less than the lower boundary of the predefined pressure range. For example, a pressure threshold for a given width of print medium may be retrieved. The obtained pressure measurement may then be compared to the pressure threshold. In one case, if the obtained pressure is less than the pressure threshold, the print medium is indicated as non-porous; if the obtained pressure is greater than the pressure threshold, the print medium is indicated as porous. If the obtained pressure is equal to the pressure threshold one of porous or non-porous may be selected as per a desired implementation. 
     According to certain examples, a calculation may be performed at block  640  to generate the porosity data from the comparison of the pressure measurement to the at least one predefined pressure range. The porosity data may, according to one example, comprise a numerical value representative of the void fraction of the print medium, which may then be compared to a predefined threshold value to indicate whether the print medium is porous or not porous. In another example, the porosity data may comprise a binary variable whose value may be used to indicate whether the print medium is porous or not porous. 
     The determining, at block  650 , whether the printing fluid collector is coupled to the printing system may, according to certain examples, comprise receiving a signal that indicates whether or not a suitable printing fluid collector is presently installed in the printing system. In one example, the signal may indicate that the printing fluid collector is installed in the printing system. In this case, the printing fluid collector not being installed in the printing system may be determined by said signal not being received. In another example, however, the signal may indicate that the printing fluid collector is not present in the printing system. In this case, the printing fluid collector being present in the printing system may be determined by said signal not being received. In at least one case, the generating of said signal may be caused by at least one switch arranged relative to the collector coupling  325 . In a further example, a user may be requested to confirm the presence of the printing fluid collector in the printing system. In this case, the signal that indicates whether or not the printing fluid collector is presently installed in the printing system may be generated by the input of the user. 
       FIG. 7  shows a method  700  of operating a printing system according to an example. The method  600  may comprise one possible implementation of the method  500 . At block  710 , a vacuum system of the printing system is operated so as to generate a fluid flow through a media path of the printing system. At block  720 , a print medium is fed along the media path until the print medium is located above the vacuum system. At block  730 , a pressure measurement is obtained from the vacuum system when the print medium is present on the media path. At block  740 , the pressure measurement obtained at block  730  is compared to at least one predefined pressure range. If the pressure measurement, P, is within a first predefined pressure range, x 1 &lt;P≤x 2 , a signal is obtained, at block  750 , indicative of whether a printing fluid collector is coupled to the printing system. In one case, the signal may be generated by at least one switch arranged in relation to the collector coupling  325 , e.g. an electro-mechanical switch arranged to alter a voltage signal when activated. Based on a value of the signal obtained at block  750  being indicative of the printing fluid collector not being coupled to the printing system, it is indicated, at block  760 , that the printing fluid collector needs to be coupled to the printing, system. At block  770 , a print operation on the printing system is inhibited until a value of the signal obtained at block  750  is obtained that indicates that the printing fluid collector is coupled to the printing system. If, at block  740 , the pressure measurement P is within a second predefined pressure range, x 2 &lt;P≤x 3 , a print operation is initiated at block  780 . If, at block  750 , a value of the obtained signal is indicative of the printing fluid collector being coupled to the printing system, a print operation is initiated at block  780 . 
     The operating of the vacuum system at block  710  may comprise, according to certain examples, driving at least one vacuum generator. The driving of the at least one vacuum generator may reduce the internal pressure of a vacuum chamber. The operating of the vacuum system may further comprise, according to certain examples, suctioning air from a first region relative to the vacuum system to a second region relative to the vacuum system, where the first region may be external to the vacuum system in at least one example. The feeding of the print medium along the media path at block  720  may comprise, in certain examples, a media transport system transporting the print medium. The media transport system may comprise at least one of a platen, rollers, motors and control circuitry. 
     The inhibiting of a print operation at block  770  may, according to various examples, comprise sending at least one signal to at least one of a control system, a media transport and a print head of the printing system, e.g. at least one of the control system  240 , the fluid deposit system  210  and the media transport system  220 . In one example, inhibiting the print operation may comprise interrupting communications between at least one of the control system, the media transport and the print head of the printing system. Similarly, initiating a print operation at block  780  may, according to various examples, comprise sending at least one signal to at least one of the control system, the media transport and the print head of the printing system. In one example, inhibiting the print operation may comprise reestablishing communications between at least one of the control system, the media transport and the print head of the printing system 
       FIG. 8  shows example components of a printing system  800 , which may be arranged to implement certain examples described herein. A processor  810  of the printing system  800  is connectably coupled to a computer-readable storage medium  820  comprising a set of computer-readable instructions  830  stored thereon, which may be executed by the processor  810 . Instruction  840  instructs the processor to obtain a signal indicative of whether a printing fluid collector is installed in relation to a media path of the printing system. Instruction  850  instructs the processor to obtain a pressure measurement from a vacuum system of the printing system, the vacuum system being located on the media path of the printing system, the pressure measurement being obtained when a printing substrate is present on the media path. Instruction  860  instructs the processor to determine information indicative of whether a printing fluid in the printing system is able to penetrate the printing substrate, based on the pressure measurement obtained based on instruction  850 . Responsive to the information indicating that the printing fluid in the printing system is able to penetrate the printing substrate and a value of the signal indicating that the printing fluid collector is not installed in relation to the media path the processor is instructed to prevent a printing operation upon the printing substrate according to instruction  870 . 
     Processor  810  can include a microprocessor, microcontroller, processor module or subsystem, programmable integrated circuit, programmable gate array, or another control or computing device. The computer-readable storage medium  820  can be implemented as one or multiple computer-readable storage media. The computer-readable storage medium  820  may include different forms of memory including semiconductor memory devices such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; magnetic disks such as fixed, floppy and removable disks; other magnetic media including tape; optical media such as compact disks (CDs) or digital video disks (DVDs); or other types of storage devices. The computer-readable instructions  830  can be stored on one computer-readable storage medium, or alternatively, can be stored on multiple computer-readable storage media. The computer-readable storage medium  820  or media can be located either in the printing system  800  or located at a remote site from which computer-readable instructions can be downloaded over a network for execution by the processor  810 . 
     The preceding description has been presented to illustrate and describe examples of the principles described. This description is not intended to be exhaustive or to limit these principles to any precise form disclosed. Many modifications and variations are possible in light of the above teaching.