Media feed mechanism for feeding sheets of porous media from a stack

Abstract

A media feed mechanism for feeding sheets of porous media from a stack of such sheets includesa support structure for supporting the stack in an aligned condition. A pick up device is arranged on the support structure. The pick up device includes a gas supply. A gas conduit is in fluid communication with the gas supply. At least one nozzle arrangement is in fluid communication with the gas conduit and is positioned to direct a flow of gas on to a first sheet of the stack, such that gas passes through the first sheet and impinges on the second sheet to create at least a partial separation of the first sheet from the second sheet. A sheet displacement mechanism is configured to engage the first sheet and to displace the first sheet away from the stack.

1 . A media feed mechanism for feeding sheets of porous media from a stack of such sheets, the feed mechanism comprising 
 a support structure for supporting the stack in an aligned condition;    a pick up device arranged on the support structure, the pick up device comprising 
 a gas supply;  
 a gas conduit in fluid communication with the gas supply;  
 at least one nozzle arrangement in fluid communication with the gas conduit and positioned to direct a flow of gas on to a first sheet of the stack, such that gas passes through the first sheet and impinges on the second sheet to create at least a partial separation of the first sheet from the second sheet; and  
 a sheet displacement mechanism that is configured to engage the first sheet and to displace the first sheet away from the stack.  
   
   
   
       2 . A media feed mechanism as claimed in  claim 1 , in which the gas supply is reversible so that the first sheet can be drawn against the, or each, nozzle arrangement once said partial separation has been created.  
   
   
       3 . A media feed mechanism as claimed in  claim 2 , in which the sheet displacement mechanism is engaged with the nozzle arrangement to displace the nozzle arrangement away from the stack of sheets once the first sheet has been drawn against the, or each, nozzle arrangement.  
   
   
       4 . A media feed mechanism as claimed in  claim 3 , which includes one nozzle arrangement that is defined by a pick up bar that defines an elongate nozzle dimensioned to span the stack of sheets, the pick up bar defining a pick up surface against which the first sheet can bear while the pick up bar is displaced from the stack of sheets.  
   
   
       5 . A media feed mechanism as claimed in  claim 4 , in which the pick up bar is shaped so that, as the gas flow is applied to the first sheet at a suitable rate, a region of relatively low pressure is generated between the pick up surface and the first sheet thereby to facilitate displacement of the first sheet towards the pick up surface.  
   
   
       6 . A media feed mechanism as claimed in  claim 4 , in which the displacement mechanism includes an axle that is rotatably mounted with respect to the support structure, a motor that is connected to the axle for rotatably driving the axle and at least one arm that is connected to an end of the axle, the pick-up bar being pivotally connected to the, or each, arm so that, on rotation of the axle, the pick-up bar is displaced along the feed path.  
   
   
       7 . A printer which comprises 
 a media feed mechanism as claimed in  claim 1;  and    a printing station that is positioned downstream of the feed mechanism to receive the first sheet and to carry out a printing operation on the first sheet.