Sheet feeding apparatus and image forming system

Abstract

A sheet feeding apparatus includes a sheet supporting portion, a sheet feeding portion configured to feed a sheet supported on the sheet supporting portion in a sheet feeding direction, an air blow unit including an air blower, an opening portion, a duct configured to form a flow path through which air flows, an adjustment portion configured to vary an opening dimension, the air blow unit being configured to separate a plurality of sheets, including an uppermost sheet, a drive source configured to drive the adjustment portion, and a control unit configured to execute a first mode in which the drive source is controlled such that the opening dimension is set to a first dimension, and a second mode in which the drive source is controlled such that the opening dimension is set to a second dimension that is smaller than the first dimension.

What is claimed is: 
     
         1 . A sheet feeding apparatus comprising:
 a sheet supporting portion configured to support a plurality of sheets;   a sheet feeding portion configured to feed a sheet supported on the sheet supporting portion in a sheet feeding direction;   an air blow unit comprising an air blower configured to blow air, an opening portion through which air blown from the air blower is blown out, a duct configured to form a flow path through which air flows between the air blower and the opening portion, an adjustment portion arranged to oppose to an upper surface of the duct and the opening portion and configured to vary an opening dimension in a height direction between the upper surface and the adjustment portion, the air blow unit being configured to separate a plurality of sheets, including an uppermost sheet, among the sheets supported on the sheet supporting portion by air blowing out from the opening portion;   a drive source configured to drive the adjustment portion; and   a control unit configured to execute, in a state where a length of the sheet supported on the sheet supporting portion in the sheet feeding direction is a first length, a first mode in which the drive source is controlled such that the opening dimension is set to a first dimension, and to execute, in a state where the length of the sheet supported on the sheet supporting portion in the sheet feeding direction is a second length that is longer than the first length, a second mode in which the drive source is controlled such that the opening dimension is set to a second dimension that is smaller than the first dimension.   
     
     
         2 . The sheet feeding apparatus according to  claim 1 , wherein the control unit is configured to control the air blower such that a rotational speed of the air blower in the second mode is faster than that in the first mode. 
     
     
         3 . The sheet feeding apparatus according to  claim 1 , wherein the adjustment portion comprises a swing member arranged in the flow path and configured to vary the opening dimension by swinging around a swing shaft positioned at a lower end portion of the swing member. 
     
     
         4 . The sheet feeding apparatus according to  claim 3 , wherein the swing member is configured to swing continuously during a sheet feeding job in which the sheet feeding portion feeds sheets,
 a swing angle of the swing member from a closed position becomes maximum in the first mode in a state where the opening dimension is set to the first dimension, the closed position being a position where the opening dimension becomes minimum, and   a swing angle of the swing member from the closed position becomes maximum in the second mode in a state where the opening dimension is set to the second dimension.   
     
     
         5 . The sheet feeding apparatus according to  claim 1 , wherein the sheet feeding portion is a roller that is configured to be in contact with the uppermost sheet supported on the sheet supporting portion and rotate to feed the uppermost sheet, and
 the opening portion is arranged to be overlapped with a contact portion where the roller and the uppermost sheet come into contact when viewed in a width direction orthogonal to the sheet feeding direction.   
     
     
         6 . The sheet feeding apparatus according to  claim 5 , further comprising a regulating member configured to regulate a position of an edge portion, in the width direction, of the sheet supported on the sheet supporting portion,
 wherein the opening portion is formed on the regulating member.   
     
     
         7 . The sheet feeding apparatus according to  claim 1 , further comprising a heater configured to increase a temperature of air blowing out from the opening portion. 
     
     
         8 . The sheet feeding apparatus according to  claim 7 , further comprising an environment sensor configured to detect an environmental condition including a temperature and a humidity of ambient atmosphere of the sheet supported on the sheet supporting portion,
 wherein the control unit is configured to set the heater to a first heater temperature in a state where a temperature and a humidity detected by the environment sensor are relatively a first temperature and a first humidity, and to set the heater to a second heater temperature that is higher than the first heater temperature in a state where the temperature and the humidity detected by the environment sensor is relatively a second temperature that is higher than the first temperature and a second humidity that is higher than the first humidity.   
     
     
         9 . The sheet feeding apparatus according to  claim 1 , further comprising an environment sensor configured to detect an environmental condition including a temperature and a humidity of ambient atmosphere of the sheet supported on the sheet supporting portion,
 wherein the control unit is configured to control the air blower to rotate at a first rotational speed in a state where the temperature and the humidity detected by the environment sensor are respectively a third temperature and a third humidity, and to control the air blower to rotate at a second rotational speed that is faster than the first rotational speed in a state where the temperature and the humidity detected by the environment sensor are respectively a fourth temperature that is higher than the third temperature and a fourth humidity that is higher than the third humidity.   
     
     
         10 . The sheet feeding apparatus according to  claim 1 , wherein in a case where the sheet feeding portion feeds the sheet according to a sheet feeding job, the air blow unit continues to blow air through the opening portion from before a first sheet of the sheet feeding job supported on the sheet supporting portion is started to be fed until a final sheet of the sheet feeding job is started to be fed. 
     
     
         11 . The sheet feeding apparatus according to  claim 1 , further comprising a display unit configured to display a selection screen on which one of a plurality of modes including the first mode and the second mode can be selected. 
     
     
         12 . An image forming system comprising:
 a sheet supporting portion configured to support a plurality of sheets;   a sheet feeding portion configured to feed a sheet supported on the sheet supporting portion to a sheet feeding direction;   an air blow unit comprising an air blower configured to blow air, an opening portion through which air blown from the air blower is blown out, a duct configured to form a flow path through which air flows between the air blower and the opening portion, an adjustment portion arranged to oppose to an upper surface of the duct and the opening portion and configured to vary an opening dimension in a height direction between the upper surface and the adjustment portion, the air blow unit being configured to separate a plurality of sheets, including an uppermost sheet, among the sheets supported on the sheet supporting portion by air blowing out from the opening portion;   a drive source configured to drive the adjustment portion;   a control unit configured to execute, in a state where a length of the sheet supported on the sheet supporting portion in the sheet feeding direction is a first length, a first mode in which the drive source is controlled such that the opening dimension is set to a first dimension, and to execute, in a state where the length of the sheet supported on the sheet supporting portion in the sheet feeding direction is a second length that is longer than the first length, a second mode in which the drive source is controlled such that the opening dimension is set to a second dimension that is smaller than the first dimension; and   an image forming unit configured to form an image on a sheet fed from the sheet feeding portion.