Gas knife apparatus and methods for stripping media from surface in printing apparatus

An apparatus useful for printing, comprising:

• a first member including a first surface;
• a second member including a second surface forming a nip with the first surface;
• a gas source;
• a flow control rotary valve in fluid communication with the gas source;
• a gas knife in fluid communication with the flow control valve, the gas knife being adapted to emit gas onto the second surface downstream from the nip;
• and
• a controller operable to control the control valve (i) to supply gas to the gas knife wherein the gas knife emits the gas having a first pressure onto the second surface, (ii) to supply gas to the gas knife wherein the gas knife emits the gas having a second pressure lower than the first pressure onto the second surface, and (iii) to stop the supply of the gas from the flow control valve to the gas knife.

A method of stripping media from a surface in an apparatus useful for printing, the apparatus comprising a first member including a first surface, and a second member including a second surface forming a nip with the first surface, the method comprising:

• feeding a first medium to the nip;
• supplying a gas from a gas source to a flow control rotary valve in fluid communication with the gas source and with a gas knife;
• supplying the gas from the flow control rotary valve to the gas knife which emits the gas having a first pressure onto the second surface of the second member downstream from the nip to strip the first medium from the second surface;
• and
• supplying the gas from the flow control rotary valve to the gas knife which emits the gas having a second pressure lower than the first pressure onto the second surface downstream from the nip to prevent a portion of the first medium that has been stripped from the second surface from re-contacting the second surface.