Automatic sheet feeding device in printing machine

Abstract

An automatic feeding device in a printing machine includes: a sheet container containing a number of sheets, a pick-up unit picking up and transporting sheets in the sheet container using a rotational friction, a driving unit driving the pick-up unit, and at least one sheet separator roller rotatably installed in a transport path of the sheets to rotate in a direction opposite to a sheet transport direction to individually separate the sheets one by one picked up by the pick-up unit. The sheet separator rollers rotate in response to a driving force of the driving unit and frictionally contact the picked sheets to separate the sheets one by one. According to the automatic feeding device, when the sheets are fed, the sheet separator rollers rotate in the direction opposite to the sheet transport direction and frictionally contact leading ends of the sheets to separate the sheets so that the sheets can be always separated in a reliable manner regardless of deformation or a type of the sheets.

What is claimed is:  
     
         1 . An automatic feeding device in a printing machine, comprising: 
 a sheet container containing a number of sheets;    a pick-up unit picking up and transporting the sheets from the sheet container using a rotational friction;    a driving unit driving the pick-up unit; and    a sheet separator roller rotatably installed in a transport path of the sheets to rotate in a direction opposite to a sheet transport direction to individually separate the sheets picked up by the pick-up unit.    
     
     
         2 . The automatic feeding device according to  claim 1 , wherein the sheet separator roller comprises: 
 first and second sheet separator rollers disposed to be spaced-apart from each other by a distance and to rotate in response to a driving force received from the driving unit.    
     
     
         3 . The automatic feeding device according to  claim 2 , wherein the sheet container comprises a rear plate, side plates extended from both sides of the rear plate, and a bottom plate extended from a lower portion of the rear plate at a given angle and having a number of dam frictions, and the first and second sheet separator rollers each is mounted on a side of the bottom plate and comprises a portion thereof projecting from the bottom plate by a height.  
     
     
         4 . The automatic feeding device according to  claim 3 , wherein the height is 0.5 to 2.0 mm inclusive.  
     
     
         5 . The automatic feeding device according to  claim 3 , wherein the first and second sheet separator rollers are made of a material having a frictional force larger than that of the dam frictions.  
     
     
         6 . The automatic feeding device according to  claim 5 , wherein the first and second sheet separator rollers are made of an elastic material.  
     
     
         7 . The automatic feeding device according to  claim 6 , wherein the sheet separator rollers each have a number of protrusions at an outer peripheral surface.  
     
     
         8 . The automatic feeding device according to  claim 3 , further comprising: 
 one shaft supported to the side plates of the sheet container and rotating in response to the driving force of the driving unit, wherein the first and second sheet separator rollers are installed on the shaft.    
     
     
         9 . The automatic feeding device according to  claim 8 , wherein the driving unit comprises: 
 a motor functioning as a driving source;    a gear train transferring the driving force from the motor to the pick-up unit; and    a driving force relay gear coupled with the shaft to engage the gear train.    
     
     
         10 . The automatic feeding device according to  claim 3 , the shaft comprises: 
 first and second shafts which are respectively supported to the side plates of the sheet container and rotating in response to the driving force of the driving unit, wherein the first and second sheet separator rollers are respectively coupled with the first and second shafts.    
     
     
         11 . The automatic feeding device according to  claim 10 , wherein the driving unit comprises: 
 a motor functioning as a driving source;    a gear train transferring the driving force from the motor to the pick-up unit;    a driving force relay gear coupled with the first shaft to engage the gear train; and    a second gear train transferring the driving force from the pick-up unit to the second shaft.    
     
     
         12 . The automatic feeding device according to  claim 3 , wherein the pick-up unit comprises: 
 a pick-up shaft rotatably supported by the side plates of the sheet container;    a pair of pick-up rollers coupled with the pick-up shaft;    a press plate installed on the rear plate of the sheet container to pivot around an upper portion of the rear plate and having a lower portion being elastically supported against the pick-up shaft; and    a spring disposed between the rear plate and the press plate.    
     
     
         13 . The automatic feeding device according to  claim 3 , further comprising: 
 a sheet guide installed in the sheet container in a longitudinally movable manner to align the sheets in the sheet container according to a size of the sheets in use.    
     
     
         14 . An automatic feeding device in a printing machine, comprising: 
 a sheet container containing a number of sheets;    a driving unit generating a driving force;    a pick-up unit picking up and transporting the sheets toward a transport path in a transport direction in response to the driving force of the driving unit; and    a sheet separator roller disposed on the transport path of the sheets, contacting leading ends of the sheets, and rotating in response to the driving force of the driving unit to separate the sheets one by one.    
     
     
         15 . The automatic feeding device according to  claim 14 , wherein the sheet separator roller rotates in a direction opposite to the transport direction of the sheets.  
     
     
         16 . The automatic feeding device according to  claim 14 , wherein the pick-up unit comprises a pick-up roller rotating in a first rotational direction to pick-up and transport the sheets through the transport path in the transport direction, and the sheet separator roller rotates in a second rotational direction opposite to the first rotational direction of the pick-up roller.  
     
     
         17 . The automatic feeding device according to  claim 14 , further comprising: 
 another sheet separator roller wherein the sheet separator roller and another sheet separator roller are disposed in a direction perpendicular to the transport direction to contact the leading ends of the sheets.    
     
     
         18 . The automatic feeding device according to  claim 14 , wherein the driving unit comprises: 
 a gear train transmitting the driving force to the pick-up unit and the sheet separator roller.    
     
     
         19 . The automatic feeding device according to  claim 14 , wherein the driving unit comprises: 
 a gear train transmitting the driving force to the pick-up unit; and    a driving force relay gear transmitting the driving force to the sheet separating roller.    
     
     
         20 . The automatic feeding device according to  claim 14 , wherein the sheet container comprises: 
 a plate disposed on the transport path to guide the sheets in the transport direction when the sheets are picked-up by the pick-up unit, wherein the sheet separator roller is rotatably disposed on the plate.    
     
     
         21 . The automatic feeding device according to  claim 20 , wherein the sheet separator roller comprises: 
 a portion protruding from a surface of the plate to contact the leading ends of the sheets.    
     
     
         22 . The automatic feeding device according to  claim 21 , wherein the plate comprises: 
 an opening through which the portion of the sheet separator roller protrudes toward the transport path of the sheets.    
     
     
         23 . The automatic feeding device according to  claim 21 , further comprising: 
 a shaft disposed on the plate opposite to the transport path to be coupled between the sheet separator roller and the driving unit.    
     
     
         24 . The automatic feeding device according to  claim 23 , further comprising: 
 a driving force relay gear formed on a first end of the shaft to receive the driving force, wherein the sheet separator roller is coupled on a second end of the shaft.    
     
     
         25 . The automatic feeding device according to  claim 21 , wherein the portion of the sheet separator roller comprises: 
 protrusions formed on an outer peripheral surface of the portion.    
     
     
         26 . The automatic feeding device according to  claim 25 , wherein the protrusions of the portion are disposed in a direction perpendicular to the transport path.  
     
     
         27 . The automatic feeding device according to  claim 25 , wherein the protrusions of the portion are disposed between the leading ends of the sheets.  
     
     
         28 . The automatic feeding device according to  claim 21 , wherein the portion of the sheet separator roller comprises: 
 grooves formed on an outer peripheral surface to receive corresponding ones of the leading ends of the sheets when the sheets are picked-up by the pick-up units.    
     
     
         29 . An automatic feeding device in a printing machine, comprising: 
 a sheet container containing a number of sheets;    a pick-up unit picking-up and transport the sheets toward a transport path in a transport direction; and    a sheet separator roller disposed on the transport path of the sheets, and rotating in a direction opposite to the transport direction to separate the sheets one by one.    
     
     
         30 . The automatic feeding device according to  claim 29 , further comprising: 
 a driving unit generating a driving force, wherein the pick-up unit and the sheet separator roller rotate in response to driving force of the driving unit.    
     
     
         31 . An automatic feeding device in a printing machine, comprising: 
 a sheet container containing a number of sheets and having a bottom plate to support the sheets;    a pick-up unit rotating to pick up and transport the sheets toward a transport path in a transport direction; and    two sheet separator rollers installed in the bottom plate of the sheet container so that the sheet separator rollers contact the sheets of the sheet container to separate the sheets one by one.