Vacuum within a pallet conveyor for a printing system

Abstract

In one example, a pallet conveyor for a printing system is described, having a track, a pallet to support a print substrate and move on the track, and a vacuum mechanism to selectively apply a vacuum at the pallet. A boundary of the vacuum applied at the pallet is synchronised with an edge of the print substrate.

1 - 9 . (canceled) 
     
     
         10 . A printing system comprising:
 a printing mechanism defining a print zone to apply printing fluid to a print substrate;   a conveyor comprising:
 a track; 
 a plurality of pallets operably coupled to and conveyable on the track through the print zone, to support the print substrate through the print zone as the pallets are conveyed on the track; and 
 a vacuum mechanism to selectively apply a vacuum at the pallets, such that a boundary of the vacuum applied at the pallets is synchronised with an edge of the print substrate. 
   
     
     
         11 . The printing system according to  claim 10 , wherein the vacuum mechanism comprises a plurality of elongate vacuum chambers spaced orthogonally to a conveyance direction of the pallets, each parallel to the conveyance direction, and connected to a first valve and a second valve for communicating vacuum to the elongate vacuum chamber. 
     
     
         12 . The printing system according to  claim 11 , wherein each elongate vacuum chamber comprises a piston defining:
 a first partition of the elongate vacuum chamber coupled to the first valve; and   a second partition of the elongate vacuum chamber coupled to the second valve;   wherein the piston is moveable longitudinally within the elongate vacuum chamber to vary the boundary of the vacuum applied when either of the first valve and the second valve is open and the other is closed.   
     
     
         13 . The printing system according to  claim 11 , comprising a plurality of pulleys driveable by a rotatable shaft to synchronise each piston, wherein each pulley comprises a belt extending a length of the elongate vacuum chamber that is moveable about the pulley, and wherein each piston is fixably coupled to a respective belt. 
     
     
         14 - 15 . (canceled) 
     
     
         16 . The printing system according to  claim 10 , wherein the conveyor comprises a plurality of sliders operably coupling the pallets to the track to convey the pallets on the track through the print zone. 
     
     
         17 . The printing system of  claim 11 , wherein the conveyor comprises a plurality of sliders operably coupling the pallets to the track to convey the pallets on the track through the print zone, each slider slidable along the vacuum mechanism and each slider having an inlet to communicate vacuum from an aperture in the elongate vacuum chambers to the pallets in the print zone. 
     
     
         18 . The printing system according to  claim 10 , wherein the track comprises an endless track, the pallets operably coupled to and conveyable around the endless track. 
     
     
         19 . A printing system comprising:
 a printing mechanism defining a print zone to apply printing fluid to a print substrate;   a track;   a pallet to move on the track to support the print substrate as the pallet passes through the print zone;   a slider to operably couple the pallet and the track to convey the pallets on the track through the print zone; and   a vacuum mechanism to selectively apply a vacuum at the pallet, such that a boundary of the vacuum applied at the pallet is synchronised with an edge of the print substrate.   
     
     
         20 . The printing system according to  claim 19 , wherein the vacuum mechanism comprises an elongate vacuum chamber arranged parallel to a conveyance direction of the pallet, and connected to a first valve and a second valve for supplying vacuum to the elongate vacuum chamber. 
     
     
         21 . The printing system according to  claim 20 , wherein the vacuum mechanism comprises a moveable surface arranged within, and moveable along a length of, the elongate vacuum chamber, such that the moveable surface defines the boundary of the vacuum applied when one of the first valve and the second valve is open and the other is closed. 
     
     
         22 . The printing system according to  claim 20 , wherein the slider is slidable along the vacuum mechanism, and comprising an inlet to communicate the vacuum from an aperture in the elongate vacuum chamber to the pallet. 
     
     
         23 . The printing system according to  claim 22 , wherein the slider comprises hinged slidable elements, the slidable elements extending in a conveyance direction and having a hinged axis perpendicular to the conveyance direction. 
     
     
         24 . The printing system according to  claim 20 , wherein the elongate vacuum chamber is one of a plurality of elongate vacuum chambers arranged substantially parallel to one another, and wherein the pallet comprises internal sections, each internal section in communication with each of the plurality of elongate vacuum chambers. 
     
     
         25 . The printing system according to  claim 20 , wherein the vacuum mechanism comprises a rotatable tube arranged within the elongate vacuum chamber, the rotatable tube comprising openings regularly spaced along a length of a surface the rotatable tube. 
     
     
         26 . The printing system according to  claim 25 , wherein:
 each of the openings is circumferentially transposed with respect to a preceding opening; and   a surface of the elongate vacuum chamber comprises regularly spaced apertures, such that rotation of the rotatable tube varies alignment between the openings in the surface of the rotatable tube and the apertures in the surface of the elongate vacuum chamber to define the boundary of the vacuum.   
     
     
         27 . The printing system according to  claim 19 , wherein the track is an endless track and the pallet circulates on the track. 
     
     
         28 . The printing system according to  claim 19 , wherein the pallet comprises a train pallet. 
     
     
         29 . The printing system according to  claim 19 , wherein the pallet comprises a wagon pallet.