Media support

Abstract

In one example, a media support with a continuous belt rotatable and suction cups lengthwise along the belt and in lines laterally across the belt to hold down a sheet of print media as the sheet is moved through a hold down area, a vacuum pump to supply vacuum to the suction cups. The vacuum control system is configured to close a supply of vacuum to all of the suction cups in the hold down area and then open the supply of vacuum sequentially to each of multiple lines of suction cups as each line enters the hold down area and then close the supply of vacuum sequentially to each of the multiple lines of suction cups as each line leaves the hold down area until all of the suction cups in the hold down area are closed.

1 . An inkjet printer, comprising:
 an inkjet printhead assembly; and   a media support system comprising:
 a media support with a continuous belt rotatable in an endless loop past the printhead assembly and suction cups arranged lengthwise along the belt and in lines laterally across the belt to hold down a sheet of print media on the belt as the sheet is moved through a hold down area near the printhead assembly; 
 a vacuum pump to supply vacuum for the suction cups; and 
 a vacuum control system configured to close a supply of vacuum to all of the suction cups in the hold down area and then open the supply of vacuum sequentially to each of multiple lines of suction cups as each line enters the hold down area and then close the supply of vacuum sequentially to each of the multiple lines of suction cups as each line leaves the hold down area until all of the suction cups in the hold down area are closed. 
   
     
     
         2 . The printer of  claim 1 , comprising a sensor configured to sense a width of the sheet entering the hold down area and wherein the vacuum control system is configured to, based on the sensor sensing the width of the sheet entering the hold down area, close the supply of vacuum to suction cups laterally outside the width of the sheet. 
     
     
         3 . The printer of  claim 2 , wherein the vacuum control system includes a manifold configured to simultaneously supply vacuum collectively to multiple lines of suctions cups, the manifold adjustable, based on the sensor sensing the width of the sheet entering the hold down area, between a first position to supply vacuum to shorter lines of suctions cups corresponding to a narrower sheet and a second position to supply vacuum to longer lines of suction cups corresponding to a wider sheet. 
     
     
         4 . The printer of  claim 3 , wherein the manifold comprises:
 multiple rows of multiple enclosures, each enclosure defining a vacuum chamber to underlay the belt;   a linear slot along a top of each enclosure to align with holes in the belt;   a tubular duct;   circumferential slots in the duct arranged to include at least one group of multiple slots and at least one single slot; and   multiple conduits each extending between the duct and one of the enclosures; and wherein the duct is:
 translatable to align some or all of the conduits to a circumferential slot according to the translational position of the duct; and 
 rotatable to connect some or all of the aligned conduits to a circumferential slot according to the rotational position of the duct. 
   
     
     
         5 . The printer of  claim 4 , comprising a sleeve around the duct to cover the circumferential slots when not aligned with a conduit. 
     
     
         6 . The printer of  claim 1 , comprising a dryer and wherein the belt is rotatable in an endless loop past the printhead assembly and past the dryer to hold down the sheet as the sheet is moved through the hold down area near the printhead assembly and near the dryer. 
     
     
         7 . The printer of  claim 1 , wherein the belt comprises multiple belts. 
     
     
         8 . A printing process, comprising:
 rotating a continuous belt in an endless loop past a printing unit;   selectively supplying vacuum to suction cups on the belt to hold down a sheet of print media as the sheet is moved through a hold down area near the printing unit, wherein the selectively supplying comprises:
 closing a supply of vacuum to all of the suction cups in the hold down area; and then 
 opening the supply of vacuum sequentially to each of multiple lines of the suction cups as each line enters the hold down area, to hold down the sheet through the hold down area; and then 
 closing the supply of vacuum sequentially to each of the multiple lines of the suction cups as each line leaves the hold down area until all of the suction cups in the hold down area are closed, to release the sheet from the hold down area; and 
   the printing unit printing to the sheet in the hold down area.   
     
     
         9 . The process of  claim 8 , comprising:
 sensing a width of the sheet entering the hold down area; and   based on the sensing, closing the supply of vacuum to suction cups laterally outside the width of the sheet during the printing unit printing to the sheet in the hold down area.   
     
     
         10 . An apparatus to hold down flexible sheets or webs flat for printing, comprising:
 a continuous belt rotatable in an endless loop;   suction cups arranged lengthwise along the belt and in lines laterally across the belt to hold down a sheet or web of print media as the print media is moved through a hold down area near the printing unit;   a sensor configured to sense a width of the print media entering the hold down area;   a vacuum pump to supply vacuum to the suction cups; and   a vacuum control system configured to:   based on the sensor sensing the width of the print media entering the hold down area, close a supply of vacuum to all of the suction cups laterally outside the width of the print media;   close the supply of vacuum to all of the suction cups in the hold down area; and then   open the supply of vacuum sequentially to each of multiple lines of suction cups as each line enters the hold down area; and then   close the supply of vacuum sequentially to each of the multiple lines of suction cups as each line leaves the hold down area until all of the suction cups in the hold down area are closed.   
     
     
         11 . The apparatus of  claim 10 , wherein the vacuum control system includes a manifold configured to simultaneously supply vacuum collectively to multiple lines of suctions cups, the manifold adjustable, based on the sensor sensing the width of the print media entering the hold down area, between a first position to supply vacuum to shorter lines of suctions cups corresponding to a narrower print media and a second position to supply vacuum to longer lines of suction cups corresponding to a wider print media. 
     
     
         12 . The apparatus of  claim 11 , wherein the manifold comprises:
 multiple rows of multiple enclosures, each enclosure defining a vacuum chamber to underlay the belt;   a linear slot along a top of each enclosure to align with holes in the belt;   a tubular duct;   circumferential slots in the duct arranged to include at least one group of multiple slots and at least one single slot; and   multiple conduits each extending between the duct and one of the enclosures; and where the duct is:
 translatable to align some or all of the conduits to a circumferential slot according to the translational position of the duct; and 
 rotatable to connect some or all of the aligned conduits to a circumferential slot according to the rotational position of the duct. 
   
     
     
         13 . The apparatus of  claim 12 , comprising a sleeve around the duct to cover the circumferential slots when not aligned with a conduit. 
     
     
         14 . The apparatus of  claim 10 , wherein the belt comprises multiple belts.