Displacing a substance

Abstract

According to some examples a substance displacement apparatus may comprise a gas ejection aperture and a deflector arm. The gas ejection aperture may be to direct gas towards a roller having a surface on which a substance is disposed. The deflector arm may be moveable between a first position in which gas is directed away from a target area on the surface of the roller, and a second position in which gas is directed towards the target area on the surface of the roller, thereby to displace at least some of the substance from the surface of the roller within the target area. A method and a print apparatus are also disclosed.

1 . An apparatus comprising:
 a first chamber formed by a deflector arm and a first housing portion;   a second chamber formed by the deflector arm and a second housing portion;   the deflector arm positioned within a gas ejection aperture formed by the first housing portion and the second housing portion, wherein the deflector arm is moveable between a first position to allow gas to pass through the gas ejection aperture from the first chamber and a second position to allow gas to pass through the gas ejection aperture from the second chamber; and   a roller to receive gas from the gas ejection aperture.   
     
     
         2 . The apparatus of  claim 1 , wherein the deflector arm is substantially planar in shape. 
     
     
         3 . The apparatus of  claim 1 , wherein the deflector arm is formed from a piezoelectric material. 
     
     
         4 . The apparatus of  claim 1 , comprising a gas guide element positioned between a portion of the gas ejection aperture and the roller. 
     
     
         5 . The apparatus of  claim 4 , wherein the gas guide element comprises a lip to prevent gas from a target area of the roller from flowing towards the target area after ejection from the gas ejection aperture. 
     
     
         6 . The apparatus of  claim 4 , wherein gas directed through the first portion of the gas ejection aperture bypasses the gas guide element to reach a target area of the roller. 
     
     
         7 . The apparatus of  claim 1 , further comprising a substance guide element to direct gas displaced from a surface of the roller away from a target area. 
     
     
         8 . The apparatus of  claim 7 , wherein the target area is a position between the substance guide and a gas guide element. 
     
     
         9 . A substance displacement method comprising:
 moving a deflector arm from a first housing portion to a second housing portion that forms a gas ejection aperture, wherein the deflector arm makes contact with a surface of the second housing portion that forms a second portion of the gas ejection aperture;   directing gas through the gas ejection aperture between the deflector arm and the first housing portion;   moving the deflector arm from the second housing portion to the first housing portion, wherein the deflector arm makes contact with a surface of the first housing portion that forms a first portion of the gas ejection aperture; and   directing gas through the gas ejection aperture between the deflector arm and the second housing portion.   
     
     
         10 . The method of  claim 9 , further comprising:
 directing gas into a first chamber located at a first side of the deflector arm and a second chamber located at a second side of the deflector arm, wherein the first chamber and the second chamber store the gas prior to being directed through the gas ejection aperture.   
     
     
         11 . The method of  claim 10 , wherein gas is directed into the first chamber and the second chamber so to maintain a gas pressure in the first chamber which is approximately equal to a gas pressure in the second chamber. 
     
     
         12 . The method of  claim 9 , wherein the deflector arm comprises a piezoelectric material, and wherein the method further comprises:
 applying a voltage to the piezoelectric material to cause the deflector arm to move between the first housing portion and the second housing portion.   
     
     
         13 . A print apparatus comprising:
 a roller having a surface on which to receive a substance to be transferred to a printable medium;   a gas delivery unit for directing gas towards the roller, the gas delivery unit comprising:
 a first chamber formed by a deflector arm and a first housing portion; 
 a second chamber formed by the deflector arm and a second housing portion; and 
 the deflector arm positioned within a gas ejection aperture to interact with the second housing portion to open a first portion of the gas ejection aperture and interact with the first housing portion to open a second portion of the gas ejection aperture; and 
   a gas guide element positioned between the gas delivery unit and the roller to receive gas directed through the second portion of the gas ejection aperture.   
     
     
         14 . The print apparatus of  claim 13 , wherein gas directed through the first portion of the gas ejection aperture is directed on to a target area of the roller. 
     
     
         15 . The print apparatus of  claim 14 , wherein the gas guide element directs gas received through the second portion of the gas ejection aperture away from the target area of the roller.