Vacuum belt feeder having a positive air pressure separator and method of using a vacuum belt feeder

In a reproduction apparatus for making copies of original information respectively on individual sheets of receiver material, apparatus for feeding such sheets seriatim from a sheet supply stack along a feed path, said sheet supply and feeding apparatus comprising:

• a platform for supporting a supply stack of individual sheets of receiver material;
• means for locating said platform within said reproduction apparatus in operative relation thereto or remote from said reproduction apparatus to enable a sheet supply stack to be readily loaded on said platform;
• a sheet feed head assembly locatable within said reproduction apparatus in operative relation thereto or remote from said reproduction apparatus, said sheet feed head assembly including a plenum, a vacuum source in flow communication with said plenum, and means associated with said plenum for urging a sheet acquired by vacuum in a sheet feeding direction away from the sheet supply stack;
• means for selectively elevating said platform, supporting the sheet supply stack, so as to maintain the topmost sheet in such stack at a predetermined level in spaced relation with respect to said urging means of said sheet feed head assembly;
• first positive air supply means for directing a flow of air at the sheet supply stack to levitate the top several sheets in the supply stack to an elevation enabling the topmost sheet to be acquired by vacuum from said sheet feed head assembly plenum, wherein said first air supply means includes a source of pressurized air and a nozzle in flow communication with said pressurized air source of said first air supply means said nozzle being located in a plane substantially coincident with the center of the supported sheet stack in a direction transverse to the sheet feed direction, and oriented so as to aim a stream of pressurized air at the top portion of a sheet supply stack supported on said stack supporting means;
• and
• second positive air supply means for directing a flow of air at an acquired sheet to assure separation of any additional sheets adhering to such topmost sheet, wherein said second air supply means includes a source of pressurized air and a plurality of nozzles in flow communication with said pressurized air source of said second air supply means said nozzles are oriented so as to aim a stream of pressurized air with a component in the direction opposite to the sheet feeding direction, toward the sheet supply stack, substantially parallel to the air stream of said first air supply means and downstream of the aim of the air stream of said first air supply means.

A method for feeding sheets seriatim from a sheet supply stack, said method comprising the steps of:

• supporting the sheet supply stack so as to maintain the topmost sheet in such stack at a predetermined level;
• directing a first flow of positive pressure air at the sheet supply stack in a plane substantially coincident with the center of the supported sheet stack in a direction transverse to the sheet feed direction to levitate the top several sheets in the supply stack to an elevation above said predetermined level, wherein the flow rate for the positive pressure air to levitate the top several sheets in the supply stack is selected to be in the range of approximately between 1.5-4.5 cu. ft./min.;
• acquiring the topmost sheet from the stack by vacuum, wherein the flow rate for the vacuum for acquiring the topmost sheet from the stack is selected to be in the range of approximately between 35-60 cu. ft./min.;
• directing a second flow of pressurized air at an acquired sheet with a component in the direction opposite to the sheet feeding direction, toward the sheet supply stack, substantially parallel to the first flow of positive pressure air, and downstream of the aim of the first flow of positive pressure air to assure separation of any additional sheets adhering to such topmost sheet, wherein the flow rate for the positive pressure air to assure separation of any additional sheets adhering to such topmost sheet is selected to be in the range of approximately between 9-27 cu. ft./min.;
• and
• urging a sheet acquired by vacuum in a sheet feeding direction away from the sheet supply stack.