Sheet guide apparatus

Abstract

A sheet guide apparatus includes an impression cylinder having a gripper device for holding a thin sheet or a thick sheet and adapted to transport the thin sheet or the thick sheet, and an air blowing device comprising an air discharge duct and discharge nozzles for blowing air on the thin sheet or thick sheet being transported by the impression cylinder. The sheet guide apparatus comprises: a displacement gauge for detecting the distance to the thin sheet or thick sheet being transported by the impression cylinder; and a control device for controlling the air blowing device, based on the detection results of the displacement gauge, to adjust the flow rate of discharged air so that the distance between the thin sheet or thick sheet and the displacement gauge becomes a distance which prevents the unstable motion of the thin sheet or thick sheet.

1 . A sheet guide apparatus including
 a transport cylinder having holding means for holding a sheet and adapted to transport the sheet, and   air blowing means for blowing air on the sheet being transported by the transport cylinder,   the sheet guide apparatus, comprising:   detection means for detecting a distance to the sheet being transported by the transport cylinder; and   control means for controlling the air blowing means, based on detection results of the detection means, such that the distance between the sheet and the detection means becomes a distance which prevents an unstable motion of the sheet.   
   
   
       2 . The sheet guide apparatus according to  claim 1 , wherein
 the control means controls the air blowing means to adjust a flow rate of discharged air so that the distance between the sheet and the detection means becomes a set distance.   
   
   
       3 . The sheet guide apparatus according to  claim 1 , wherein
 the distance which prevents the unstable motion of the sheet differs according to whether the sheet is a thin sheet or a thick sheet.   
   
   
       4 . The sheet guide apparatus according to  claim 3 , wherein
 the distance, which prevents the unstable motion of the thick sheet when the sheet is the thick sheet, is shorter than the distance which prevents the unstable motion of the thin sheet when the sheet is the thin sheet.   
   
   
       5 . The sheet guide apparatus according to  claim 1 , wherein
 the detection means is provided on a downstream side in a sheet transport direction with respect to the air blowing means and on an upstream side in the sheet transport direction with respect to a cylinder in contact with the transport cylinder.   
   
   
       6 . The sheet guide apparatus according to  claim 1 , wherein
 the detection means is provided at a position opposing a surface of the sheet.   
   
   
       7 . The sheet guide apparatus according to  claim 1 , further comprising
 a sheet thickness input unit for inputting a thickness of the sheet, and wherein   the control means judges the sheet as a thin sheet when the thickness of the sheet inputted by the sheet thickness input unit is less than a given value, and judges the sheet as a thick sheet when the thickness of the sheet inputted by the sheet thickness input unit is the given value or higher.   
   
   
       8 . The sheet guide apparatus according to  claim 1 , further comprising
 a sheet thickness input unit for inputting a thickness of the sheet, and wherein   the control means judges the sheet as a thin sheet when the thickness of the sheet inputted by the sheet thickness input unit is a given value or lower, and judges the sheet as a thick sheet when the thickness of the sheet inputted by the sheet thickness input unit exceeds the given value.   
   
   
       9 . The sheet guide apparatus according to  claim 1 , wherein
 the air blowing means includes an air discharge duct having discharge holes, and discharge nozzles, and   the control means exercises control such that air is discharged from the discharge holes of the air discharge duct and the discharge nozzles when the sheet is a thick sheet, and exercises control such that air is discharged only from the discharge holes of the air discharge duct when the sheet is a thin sheet.   
   
   
       10 . The sheet guide apparatus according to  claim 1 , wherein
 the distance which prevents the unstable motion of the sheet when the sheet is a thick sheet is a distance from a position between a sheet motion instability position and an improper position to the detection means,   the sheet motion instability position being a position at which the sheet is excessively separated from the transport cylinder, and   the improper position being a position at which the sheet is excessively close to the transport cylinder.   
   
   
       11 . The sheet guide apparatus according to  claim 1 , wherein
 the detection means is a displacement gauge.