Abstract:
In a method for limiting a height of a stack of sheets in an output holder of an image reproduction system, the output holder being configured to hold a stack of sheets printed upon by the image reproduction system according to a print job submitted to the image reproduction system, the image reproduction system including a control unit for controlling the receiving and printing of the print job, the method includes receiving a print job at the image reproduction system, the print job comprising image data to be printed and a plurality of print job settings, starting printing the print job by the image reproduction system, and delivering printed sheets of the print job to the output holder. The plurality of print job settings include a setting for a maximum height of a stack in the output holder settable per print job, the method including establishing a value for the setting for the maximum stack height of the stack, and stopping the delivering of the printed sheets of the print job to the output holder upon the stack reaching the maximum height set in the setting for the maximum stack height. An image reproduction system is configured to execute the method.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119(a) to Application Nos. 15166114.7 and 14191044.8, filed in Europe on Oct. 30, 2014 and May 1, 2015, respectively. The entire content of each of the identified-identified applications is hereby incorporated by reference into the present application. 
       BACKGROUND OF THE PRESENT INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a method for limiting a height of a stack of sheets in an output holder of an image reproduction system, the output holder being configured to hold a stack of sheets printed upon by the image reproduction system according to a print job submitted to the image reproduction system, the image reproduction system comprising a control unit for controlling the receiving and printing of the print job, the method comprising the steps of receiving a print job at the image reproduction system, the print job comprising image data to be printed and a plurality of print job settings, starting printing of the print job by the image reproduction system, and delivering printed sheets of the print job to the output holder. 
         [0004]    The image reproduction system may be a printer, a copier, a multi-functional apparatus or a facsimile apparatus. The sheets may be a kind of medium type, like plain paper, coated paper, transparent sheets, fabric, plastic, wood or metal. 
         [0005]    The present invention further relates to an image reproduction system, which is configured to apply the method according to the present invention and a non-transitory computer readable medium comprising computer executable program code configured to instruct a computer to perform the method according to the present invention in an image reproduction system according to the present invention. 
         [0006]    2. Description of Background Art 
         [0007]    Print jobs are printed consecutively by means of an image reproduction system. After printing upon sheets by the image reproduction system, the sheets are transported to an output holder attached to the image reproduction system. The output holder may be part of the image reproduction system or coupled to an outlet of the image reproduction system. The output holder has a maximum capacity expressed in a maximum number of sheets in the output holder, expressed in a maximum weight of the amount of sheets in the output holder, and/or expressed in a maximum stack height of the sheets in the output holder. The sheets form a stack of sheets in the output holder. The stack height is limited due to physical limitations. Typically, the output holder itself provides a device to report a full output holder when a boundary value is passed. Such a device may be a sensor in the output holder. When the output holder is full, the image reproduction system will stop printing to the output holder. The boundary value can be set by setting a system setting of the print system. 
         [0008]    Nowadays, the stack height may be limited according to a system setting for the image reproduction system for all jobs. A problem arises when a slope appears in the stack of finished sheets. The slope may be the result of a sheet curl, a toner distribution on the sheet and/or media characteristics. For example, a medium type may have a sticker at a top right side of the sheet. Another problem arises when post processing of the print job has a constraint with respect to the stack height. For example, a client of the image reproduction system—this may be an offline finisher or an end customer—prescribes for a specific print job a use of specific heights for the printed output. 
         [0009]    It is an objective of the present invention to overcome these problems in a user friendly and productive manner. 
       SUMMARY OF THE INVENTION 
       [0010]    To achieve the above objective, the plurality of print job settings comprises a setting for a maximum height of a stack in the output holder, the maximum height being settable per print job, and the method comprises the step of establishing a value for the setting for the maximum stack height of the stack, and stopping the delivering of the printed sheets of the print job to the output holder upon the stack reaching the maximum height set in the setting for the maximum stack height. 
         [0011]    According to an embodiment of the present invention, the step of establishing the value for the setting for the maximum stack height of the stack comprises the step of entering the value for the setting for the maximum stack height in a job submission tool, which is suitable for submitting the print job to the image reproduction system. The setting for the maximum stack height can be entered per job intended to be submitted to the image reproduction system. The maximum stack height may be entered in SI units (cm or mm), number of sheets or number of sets. If a number of copies is specified for the print job, the printed print job will deliver as many sets as the specified number of copies. 
         [0012]    According to an embodiment of the present invention, the step of establishing the value for the setting for the maximum stack height of the stack comprises the step of entering the value for the setting for the maximum stack height per medium type to be used for printing the print job, the medium type having a medium property that determines a maximum stack height for the stack in the output holder for said medium type. By defining the maximum stack height as a medium property of a medium type, each print job using that medium type implicitly has at least one setting for the maximum stack height. 
         [0013]    According to an embodiment of the present invention, the method comprises the step of determining the maximum stack height of the stack in the output holder that will be used while printing the print job, to be the maximum stack height entered when using the job submission tool. If a maximum stack height is set as a system setting or as a medium property, and also a maximum stack height is set as a print job setting in the print job, the maximum stack height setting set as a print job setting in the print job will prevail. 
         [0014]    According to an alternative embodiment of the present invention, the method comprises the step of determining the maximum stack height of the stack in the output holder that will be used while printing the print job, to be the minimum of the maximum stack height entered in the job submission tool and the maximum stack height entered for the medium type. This is advantageous in cases in which a secured implementation is needed. 
         [0015]    According to an embodiment of the present invention, the method comprises the step of entering a second maximum stack height for a submitted print job on a local user interface of the image reproduction system, wherein the second maximum stack height overrules the maximum stack height set in the print job settings of the print job. 
         [0016]    According to an embodiment of the present invention, the method comprises the step of expressing the maximum stack height in a number of sheets in the stack or in a number of sets in the stack. This is advantageous in case a slope of the stack varies dependent on the image data to be printed, or the kind of finishing like stapling, punching, binding, etc. The operator can determine once the maximum number of sheets or the maximum number of sets on the stack does not lead to any problem. If a number of copies is specified for the print job, the printed print job will deliver as many sets as the specified number of copies. 
         [0017]    According to an embodiment of the present invention, the step of stopping the delivering of the printed sheets of the print job to the output holder upon the stack reaching the maximum height set in the setting for the maximum stack height, takes into account the height of printed sheets which are already present in the output holder before starting of the printing of the print job. The output holder may not be empty when starting the printing of the print job. The stack formed in the output holder may already be of a significant height. 
         [0018]    According to an embodiment of the present invention, the method comprises the step of detecting a stack of sheets in the output holder before starting of the printing of the print job having a maximum stack height set in the print job settings, and removing the stack of sheets from the output holder before starting of the printing of the print job. This is advantageous in that the print job starts with an empty output holder. If, for example, the print job has a maximum stack height set in order to let the stack of output of the print job fit in a package after the stack is removed from the output holder, it is efficient that the complete stack printed according to the print job can be put in the package. 
         [0019]    The invention also relates to an image reproduction system for printing a print job on sheets, the print job comprising image data and a plurality of print job settings, the image reproduction system comprising a print engine, an output holder configured to hold a stack of sheets printed upon by the printing engine according to the print job submitted to the image reproduction system, a control unit for controlling the receiving of the print job in the image reproduction system and the printing of the print job, and a receiving device being part of the image reproduction system for receiving the submitted print job, wherein the plurality of print job settings comprises a setting for a maximum height of a stack in the output holder settable per print job, and wherein the control unit is configured to establish a value for the setting for the maximum stack height of the stack and to stop delivering of printed sheets of the print job to the output holder upon the stack in the output holder reaching the maximum height set in the setting for the maximum stack height. Further embodiments of the image reproduction system are configured to execute any of the embodiments of the method according to the present invention mentioned here-above and hereinafter. 
         [0020]    The present invention also relates to a non-transitory computer readable medium comprising computer executable program code configured to instruct a computer to perform the method according to the invention. 
         [0021]    Therefore, the present invention pertains to: 
         [0022]    According to a first aspect, a method for limiting a height of a stack of sheets in an output holder of an image reproduction system, the output holder being configured to hold a stack of sheets printed upon by the image reproduction system according to a print job submitted to the image reproduction system, the image reproduction system comprising a control unit for controlling the receiving and printing of the print job, the method comprising the steps of: 
         [0023]    receiving a print job at the image reproduction system, the print job comprising image data to be printed and a plurality of print job settings; 
         [0024]    starting printing of the print job by the image reproduction system; and 
         [0025]    delivering printed sheets of the print job to the output holder, 
         [0026]    wherein the plurality of print job settings comprises a setting for a maximum height of a stack in the output holder, the maximum height being settable per print job, and 
         [0027]    the method further comprising the steps of: 
         [0028]    establishing a value for the setting for the maximum stack height of the stack; and 
         [0029]    stopping the delivering of the printed sheets of the print job to the output holder upon the stack reaching the maximum height set in the setting for the maximum stack height. 
         [0030]    According to a second aspect, in the method of the first aspect, the method further comprises the step of expressing the maximum stack height in a number of sheets in the stack or in a number of sets in the stack. 
         [0031]    According to a third aspect, in the method of the first or second aspects, the step of stopping the delivering of the printed sheets of the print job to the output holder upon the stack reaching the maximum height set in the setting for the maximum stack height, takes into account the height of printed sheets which are already present in the output holder before starting the printing of the print job. 
         [0032]    According to a fourth aspect, in the method of any of the first through third aspects, the method further comprises the step of detecting a stack of sheets in the output holder before starting of the printing of the print job having a maximum stack height set in the print job settings; and removing the stack of sheets from the output holder before starting of the printing of the print job. 
         [0033]    According to a fifth aspect, in the method of any of the first through fourth aspects, the method further comprises the step of entering a second maximum stack height for a submitted print job on a local user interface of the image reproduction system, wherein the second maximum stack height overrules the maximum stack height set in the print job settings of the print job. 
         [0034]    According to a sixth aspect, in the method of any of the first through fifth aspects, the step of establishing the value for the setting for the maximum stack height of the stack further comprises the step of entering a value for the setting for the maximum stack height in a job submission tool suitable for submitting the print job to the image reproduction system. 
         [0035]    According to a seventh aspect, in the method of the sixth aspect, the method further comprises the step of determining the maximum stack height of the stack in the output holder that will be used while printing the print job, to be the maximum stack height entered when using the job submission tool. 
         [0036]    According to an eighth aspect, in the method of any of the first through sixth aspects, the step of establishing the value for the setting for the maximum stack height of the stack further comprises the step of entering a value for a medium type to be used for printing the print job, the medium type having a medium property that determines a maximum stack height for the stack in the output holder for said medium type. 
         [0037]    According to a ninth aspect, in the method of the eighth aspect, the method further comprises the step of determining the maximum stack height of the stack in the output holder that will be used while printing the print job, to be the minimum of the maximum stack height entered in the job submission tool and the maximum stack height entered for the medium type. 
         [0038]    An image reproduction system for printing a print job on sheets, the print job comprising image data and a plurality of print job settings, the image reproduction system comprising a print engine, an output holder configured to hold a stack of sheets printed upon by the printing engine according to a print job submitted to the image reproduction system, a control unit for controlling the receiving and the printing of the print job, and a receiving device for receiving the submitted print job, wherein the plurality of print job settings comprises a setting for a maximum height of a stack in the output holder settable per print job, wherein the control unit is configured to establish a value for the setting for the maximum stack height of the stack, and wherein the control unit is configured to stop delivering of printed sheets of the print job to the output holder upon the stack in the output holder reaching the maximum height set in the setting for the maximum stack height. 
         [0039]    A non-transitory computer readable medium comprising computer executable program code configured to instruct a computer to perform the method according to any one of the first through ninth aspects of the method in an image reproduction system according to the present invention. 
         [0040]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0041]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
           [0042]      FIG. 1  schematically illustrates an image reproduction system in which the method according to the present invention is applicable; 
           [0043]      FIG. 2  schematically illustrates a user interface window of a job submitter for submitting a print job to the image reproduction system according to the method of the present invention; 
           [0044]      FIG. 3  schematically illustrates a user interface window for displaying media properties of a media used in a print job submitted to the image reproduction system according to the invention; 
           [0045]      FIG. 4  schematically illustrates the user interface window for representing a print job queue of the image reproduction system according to the invention; 
           [0046]      FIG. 5  is a flow diagram of an embodiment of the method according to the present invention; and 
           [0047]      FIG. 6  is a flow diagram of a further embodiment of the method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0048]    The present invention will now be described with reference to the accompanying drawings, wherein the same or similar elements are identified with the same reference numerals throughout the several views. 
         [0049]      FIG. 1  schematically illustrates an image reproduction system  1  in which the method according to the present invention is applicable. The image reproduction system  1 , for purposes of explanation, is divided into an output section  5 , a print engine and control section  3 , a local user interface  7  and an input section  4 . While a specific image reproduction system is shown and described, the disclosed embodiments may be used with other types of image reproduction system, such as ink jet, electrographic, etc. 
         [0050]    The output section  5  comprises at least one output holder  52  for holding printed image receiving material. The printed image receiving material is transported from the print engine and control section  3  via an inlet  53  to the output section  5 . When a stack ejection command is invoked by the control unit  37 , guides  54 , for instance in the form of rollers, are activated in order to eject the stack on the output holder  52  outwards to an external output holder  51 . The operator can take the stack from the external output holder  51  for further processing the outputted documents in the stack. Finishing equipment may be added to or replace the external holder  51  for further finishing of the ejected stack. The internal output holder  52  may not be reachable by an operator. In such case, the operator cannot take the stack from the internal output holder  52  for further processing, but can only take the stack from the external output holder  51  for further processing. The height of the stack on the output holder  52  is physically limited by the space height in the output section  5  as indicated by a double-sided arrow  55 . 
         [0051]    A print job may be printed by the print engine and control section  3  and outputted to the output section  5 . The print job may have a setting for a maximum stack height in the output holder  52  according to the present invention. The print engine may deliver printed sheets to the output holder  52  until the maximum stack height set in the print job settings is reached. At the moment that the maximum stack height is reached, the printing may stop and the operator can empty the output holder  52  or the stack is ejected to the external output holder  51  and the operator can empty this external output holder  51 . The emptying action of the operator is actually the ejection of the stack. Stopping of delivering sheets to the output holder  52  may imply that the printing by the image reproduction system is stopped. However, an image reproduction system having a large internal buffer for holding sheets does not have to stop printing, but can just stop the transfer of sheets from the large internal buffer to the output holder  52 . 
         [0052]    According to an alternative embodiment (not shown), the image reproduction system comprises a first output holder and a second output holder and sheets are automatically transferred to the second output holder when the first output holder has to be emptied. If the print job uses both the first and the second output holder, the maximum stack height according to the print job settings of the print job may be valid for both output holders. 
         [0053]    The output section  5  is digitally connected by means of a cable  60  to the print engine and control section  3  for bi-directional data signal transfer. 
         [0054]    The print engine and control section  3  comprises a print engine and a control unit  37  for receiving print jobs submitted to the image reproduction system  1  and for controlling the printing process. The control unit is a computer or server or a workstation, connected to the print engine and connected to the digital environment of the image reproduction system, for example a network N for transmitting a submitted print job to the image reproduction system. In  FIG. 1 , the control unit  37  is positioned inside the print engine and control section  3 , but the control unit  37  may also be positioned outside the print engine and control section  3  in connection with the network N, for example as a workstation N 1 . The print engine comprises a print head or print assembly  31  for ejecting or fixing marking material to image receiving material and a paper path  32 ,  34 ,  35  for transporting the image receiving material from an entry point  36  of the print engine and control section  3  to the inlet  53  of the output section  5 . The print head or print assembly  31  is positioned near the paper path section  34 . The print head or print assembly  31  may be an inkjet print head, a direct imaging toner assembly or an indirect imaging toner assembly. While an image receiving material is transported along the paper path section  34 , the image receiving material receives the marking material from the print head or print assembly  31 . A next paper path section  32  is a flip unit for selecting a different subsequent paper path for simplex or duplex printing of the image receiving material. The flip unit  32  may also be used to flip a sheet of image receiving material after printing in simplex mode before the sheet leaves the print engine and control section  3  via a curved section  38  of the flip unit  32  and via the inlet  53  to the output section  5 . The curved section  38  of the flip unit  32  may not be present and the turning of a simplex page has to be done via another paper path section  35 . The paper path sections  32 ,  34 ,  35  are exemplary for the present invention but other embodiments of the paper path may be envisioned. 
         [0055]    When the image receiving material has been printed upon, the image receiving material is transported to the inlet  53  of the output section  5 . 
         [0056]    The input section  4  may comprise at least one input holder  44 ,  45 ,  46  for holding the image receiving material before transporting the sheets of image receiving material to the print engine and control section  3 . Sheets of image receiving material are guided from the input holders  44 ,  45 ,  46  by guides  42 ,  43 ,  47  to an outlet  36  for entrance in the print engine and control section  3 . 
         [0057]    The local user interface is suitable for displaying user interface windows for controlling a print job queue residing in the control unit  37 . In another embodiment, a computer N 1  in the network N has a user interface for displaying and controlling the print job queue of the image reproduction system  1 . 
         [0058]      FIG. 2  shows a window  200  of a job submitter for submitting a print job to the image reproduction system  1  shown in  FIG. 1 . The job submitter may be part of a pre-processing application or a printer driver. The pre-processing application may comprise a hot folder mechanism for receiving document files in a hot folder and automatically retrieving the document files subsequently from the hot folder in order to transmit the document files subsequently to the image reproduction system. 
         [0059]      FIG. 2  shows a window  200  comprised in a printer driver application. 
         [0060]    From three tabs “Advanced,” “Job,” “Printer,” the second tab “Job” is selected. 
         [0061]    A number of copies may be selected in a first entry field  230 . A job name may be entered in a second entry field  240 . 
         [0062]    A plurality of settings may be set for a layout of the print job and a medium type of the print job. The medium type of the print job may be defined in a tab section  260  called “Paper.” When expanding this tab section  260 , the medium type intended to be used for the print job will be displayed. The tab section  260  may also comprise an entrance item to enter a user interface window for defining or changing the properties of the medium type. Such a user interface window is shown in  FIG. 3 . 
         [0063]    Image parameters and finishing parameters may be set. The finishing parameters are selected and expanded. Finishing parameters concern a page order, a collate option, a banner page option and an output option. According to an embodiment of the present invention, one of the finishing parameters is a maximum stack height option  210  for defining a maximum height of a stack in the output holder of the image reproduction system  1  as shown in  FIG. 1 . In a selection box  220 , a maximum stack height of 150 mm is selected from a list of maximum stack height options (not shown). The list may comprise for example heights of 50 mm, 100 mm, 122 mm, 150 mm, 200 mm, 250 mm, until a maximum stack height that is limited by the physical space  55  as shown in  FIG. 1  is reached. The list may also comprise a “don&#39;t care” option if no maximum stack height is required for the print job. The “don&#39;t care” option may be the default option for the maximum stack height setting. According to an alternative embodiment, the list also comprises heights measured in a number of sheets or a number of sets to be delivered in the output holder. The selection box  220  may also be in the form of a combo box or a free format field, wherein the user is able to enter a specific value in mm, cm, a number of sheets or a number of sets. 
         [0064]    The maximum stack height option  210  is displayed in the form of a selection drop-down box. Other forms of the maximum stack height option may be envisioned, for example a set of radio buttons, a combo box, a free format field, etc. 
         [0065]    The selected print job in the second entry field  240  has a job name “print job 1.” The print job named “print job 1” may be submitted to the image reproduction system by means of the submit button  250 . 
         [0066]      FIG. 3  shows a user interface window  300  according to an embodiment of the present invention. The user interface window  300  comprises entry fields  301 - 316  for defining or changing medium properties of a medium type. 
         [0067]    A first entry field  301  is used to enter a name of the medium type, for example “Black Label.” A second entry field  302  is used to enter a kind of the medium type, for example “TopColor,” i.e. an indication of the quality or brand of the medium type. A third entry field  303  is used to enter a size of the medium type, for example A4. If the medium type has a size, which is not predefined by a print standard, a fourth entry field  304  and a fifth entry field  305  may be used to enter a width and a length, respectively, of the medium type. A sixth entry field  306  is a checkbox for checking if the medium type is a tab medium. A seventh entry field  307  is a checkbox for checking if the new medium type is used as an insert. An eighth entry field  308  is used to enter a cycle length of the medium type. A ninth entry field  309  is used to enter a punch count of the medium type. A tenth entry field  310  is used to enter a weight of one sheet of the medium type, for example in gram/m 2 . An eleventh entry field  311  is used to enter a color of the medium type, for example “White.” A twelfth entry field  312  is a checkbox for checking if specific RGB values  413 ,  414 ,  415  for respectively red, green and blue are required with respect to screen colors of a preview. A thirteenth entry field  316  is used for defining the maximum stack height of the medium type. The entry field  316  is in the form of a selection box, but use of radio buttons, use of a combo box, or use of a free format field may be envisioned. By defining the maximum stack height in the entry field  316  for the medium type, a print job using this medium type will implicitly have a setting for the maximum stack height in mm, in cm, in a number of sheets or in a number of sets. 
         [0068]    A reference link  319  to entry fields for advanced media properties is presented at the end of the list of entry fields  301 - 316 . Other entry fields than the mentioned entry fields may be envisioned and fall within the scope of the present invention. A confirmation button  330  is used when values entered for the entry fields are to be confirmed and saved. A cancel button  340  is used for cancelling the user action on the user interface window  300 . 
         [0069]      FIG. 4  shows a user interface window  400  of the image reproduction system  1  according to an embodiment of the present invention. The user interface window  400  is opened at the local user interface  7  in  FIG. 1  and shows a representation of the print job queue residing in the control unit  37  in  FIG. 1 . 
         [0070]    The user interface window  400  comprises a title section  410 , a user action section  420 , a print job queue section  430  and a navigation section  440 . 
         [0071]    The user action section  420  comprises image items  422  -  426  to be selected for executing actions on a print job queue  43 A in the print job queue section  430 . A first image item  422  represents a job removal action. A second image item  423  represents a job duplication action. A third image item  424  represents a move up action. A fourth image item  425  represents a move down action. A fifth image item  426  represents an action to retrieve and display print job settings of a selected print job in a properties window. 
         [0072]    The navigation section  440  comprises a first image item  441  for navigating to a schedule with a timeline and medium types needed for the print jobs, a second image item  442  for navigating to an overview of the input trays and the content of the input trays, a third image item  443  for navigating to the system settings and a fourth image item  444  for navigating to the print jobs in the print job queue  43 A. In the user interface window  400 , the fourth image item  444  is selected. 
         [0073]    The print job queue section  430  comprises a representation of the print job queue  43 A. The print job queue  43 A comprises at least one print job.  FIG. 4  shows a plurality of print jobs  431 - 437  in the print job queue  43 A in a sequence order from top to bottom. A first print job  431  will be printed real soon after the print job that is currently printed by the image reproduction system is ready. A last print job  437  will be printed if the preceding print jobs  431 - 436  are ready. Each print job  431 - 437  in the print job queue  43 A is selectable by a mouse or by a finger or stylus in case of a touch screen. A sequence order of the print jobs  431 - 437  in the print job queue  43 A may be changed by selecting a print job in the print job queue  43 A and then activating the fourth image item  424  or the fifth image item  425  in order to move the selected print job one position up or down respectively in the print job queue  43 A. In a further embodiment in case of a touch screen, a position of a print job  431 - 437  in the print job queue  43 A may be changed by dragging and dropping the appropriate print job to another position in the print job queue  43 A. The print job queue  43 A is scrollable by activating an upward scrolling button  438  or a downward scrolling button  439 . Each print job  431 - 437  in the print job queue  43 A may be displayed with a number of print job settings of the print job, such as an identifying name of the print job (“Print job 1”), a size of the image receiving material to be used for the print job (“A3”), a maximum stack height to be used for the print job (“15 cm”), etc. For convenience reasons, a small relevant number of properties for each print job  431 - 437  is displayed in the print job queue  43 A. 
         [0074]    A use of the fifth image item  426  representing the print job settings of the print job will be further elucidated. The operator is able to select a print job from the print job queue  43 A. After the selection of the print job, the operator may activate the fifth image item  426 . By activating the fifth image item  426  the print job settings of the selected print job are displayed in another window. Such a window may be similar to the user interface window  300  shown in  FIG. 3 . The operator is now able to establish a value for the setting of the maximum stack height. In this way, the operator is able to enter or change the setting for the maximum stack height for a print job residing in the print job queue  43 A of the image reproduction system. 
         [0075]    A maximum stack height may be set for a relative large print job, for example a print job, which has an amount of output that exceeds the height of the output holder once or several times. For a relatively large job, a stack ejection before the start of the relatively large job may be planned automatically—for example by a rule based system—or manually by the operator. 
         [0076]    A maximum stack height may be set for a relatively small print job. When relatively small jobs are consecutively scheduled in the print job queue  43 A, no stack ejection may take place in between the consecutive print jobs. The control unit may register stack ejections and check—before printing the consecutive print jobs—if the amounts of sheets in the output holder at any time during the planned printing of the consecutive print jobs will exceed a maximum stack height of one of the consecutive print jobs. When a print job is detected that will exceed its maximum stack height set in the print job settings corresponding to the print job when printing the print job, the control unit may schedule a stack ejection before the detected print job. 
         [0077]    According to an embodiment, the criteria employed by the operator for maximum stack heights per print job may be encoded in software for a rule base system comprising rules for maximum stack heights based on the print job settings of the print jobs in the print job queue of the image reproduction system and/or based on media properties of a medium type specified in the print job settings of the print job. The rule based system may be part of the control unit of the image reproduction system according to the present invention. The application of the rules in the rule based system may lead to an automatic stack ejection without intervention of the operator if a maximum stack height for a print job is reached. 
         [0078]    According to an embodiment, feedback is displayed when a maximum stack height set in the print job settings of a print job are in conflict with physical boundaries of the output holder, or in conflict with a maximum stack height set in the media properties of a medium type, which medium type is intended to be used for the print job. The operator is able to select the correct maximum stack height from a user interface window (not shown) before the printing of the print job will start. 
         [0079]      FIG. 5  is a flow diagram of an embodiment of the method according to the present invention. A starting point A leads to the first step S 1 . 
         [0080]    A print job may be created by a print job creation tool like a print job submitter, a printer driver, a document creation application, a document preparing tool, etc. The print job comprises image data to be printed and a plurality of print job settings. Among the plurality of print job settings, a value for the setting for the maximum stack height for the output of the print job is set according to the present invention. Usually, the creation of the print job takes place outside the image reproduction system on a computer in a—wired or wireless—network connected to the image reproduction system. The print job has been submitted to the image reproduction system via the network, wired or wireless. 
         [0081]    In the first step S 1  of the method, the print job is received at the image reproduction system by the control unit of the image reproduction system. The print job is scheduled in a print job queue residing in memory of the control unit. 
         [0082]    In a second step S 2 , a maximum stack height is established from the print job settings of the print job. The maximum stack height may be directly retrieved from the print job settings of the print job or may be retrieved from a dedicated medium type setting for the maximum stack height of the medium type, which medium type is set in the print job settings. In the latter case, the control unit may consult a media list or media catalogue comprising media properties of medium types defined for the image reproduction system. 
         [0083]    In a third step S 3 , it is checked if the print job is completed, i.e. if all sheets of the print job are printed. If so, the method ends in endpoint B. If not, the method proceeds to a fourth step S 4 . 
         [0084]    In the fourth step S 4 , it is checked whether or not the maximum stack height is reached. 
         [0085]    This may be checked by reading out sensors in the output holder or by counting the already printed sheets. In the latter case, the already printed sheets on the stack may be originated from print jobs, which have preceded the current print job. Since the medium type and the thickness of a sheet of the medium type used by the current print job and used by any preceding print job, which printed sheets are in the stack, are known—the thickness is a media property—a simple calculation provides the height of the stack in the output holder formed by the already printed sheets. If the maximum stack height is reached, the method proceeds to a sixth step S 6 . If the maximum stack height is not reached, the method proceeds to a fifth step S 5 . 
         [0086]    In a fifth step S 5 , a sheet is printed according to the print job and delivered on top of the stack in the output holder. After the sheet is printed, the method returns to the third step S 3 . 
         [0087]    In the sixth step S 6 , delivering of printed sheets to the output holder is stopped. The print process may be temporarily stopped or an internal buffer may be stopped to deliver sheets to the output holder. Printing may be temporarily stopped to give the operator an opportunity to empty the output holder. 
         [0088]    In a seventh step S 7 , the stack which has reached the maximum stack height is removed from the output holder. The removal may be an ejection from the output holder to an external tray. The removal may also be a manual removal of the stack of sheets by an operator. After the removal of the stack from the output holder, the method returns to the third step S 3 . 
         [0089]      FIG. 6  is a flow diagram of another embodiment of the method according to an embodiment of the present invention. This embodiment comprises the embodiment of  FIG. 5  with additional steps T 1 -T 3  between the second step S 2  and the third step S 3  of the embodiment in  FIG. 5 . 
         [0090]    In a first step T 1 , it is checked whether or not there is a stack of sheets in the output holder before the start of the printing of the print job. This can be checked by a detection of a stack in the output holder by means of sensors or cameras in the output holder. This can also be checked by calculations of a number of sheets ejected in previous print jobs in combination with registrations of former stack ejections or stack removals by the control unit. If there is no stack of sheets in the output holder, the method can proceed with the third step S 3  in  FIG. 5 . If there is a stack of sheets in the output holder, the method can proceed to a second step T 2 . 
         [0091]    In the second step T 2 , it is checked whether there is a maximum stack height set in a print job setting of the print job or in a media property of a medium type used in the print job. If there is no maximum stack height set, for example a “don&#39;t care” option for the maximum stack height setting, the method proceeds to the third step S 3  of  FIG. 5 . If there is a maximum stack height set in the print job settings of the print job or in a media property of the medium type used in the print job, the method proceeds to a third step T 3 . 
         [0092]    In the third step T 3 , the stack of sheets is removed from the output holder before starting of the printing of the print job. The removal may be an automatic stack ejection or a manual removal by the operator. After removal of the stack, the method proceeds to the third step S 3  in  FIG. 5 , the print job can start and the empty output holder will be filled with sheets from the print job. This is advantageous if it is not desired to have sheets of previous print jobs in the stack together with sheets of the starting print job. This may be for example the case when the output of the starting print job needs to be packed in boxes of a predetermined height. This may be for example the case when the output of the starting job needs to be finished by means of a finishing device which has a stack height limitation for insertion or processing of a printed stack of sheets in the finishing device. 
         [0093]    The present invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.