Sheet separating device with noise suppressing function and auto document feeder having such sheet separating device

Abstract

A sheet separating device having a noise suppressing function is used with an auto document feeder. The sheet separating device includes a sheet separating pad, a sheet separating holder, a resilient element and a noise suppressing element. The sheet separating pad cooperates with a sheet separating roller to separate a paper sheet fed into a sheet-guiding path of the auto document feeder. The sheet separating pad is disposed on the sheet separating holder. The resilient element is sustained against or coupled to the sheet separating holder, so that sheet separating pad disposed on the sheet separating holder is urged against the sheet separating roller. The noise suppressing element is arranged on the sheet separating holder for altering the natural frequency dynamic response of an assembly of the sheet separating pad and the sheet separating holder, thereby shifting the natural frequency dynamic response of the assembly of the sheet separating pad and the sheet separating holder from the working frequency and the harmonic frequency of the sheet separating roller.

1 . A sheet separating device having a noise suppressing function to be used with an auto document feeder, said auto document feeder comprising a sheet separating roller in a sheet-guiding path, said sheet separating device comprising:
 a sheet separating pad arranged in said sheet-guiding path and facing said sheet separating roller, and cooperating with said sheet separating roller to separate a paper sheet fed into said sheet-guiding path;   a sheet separating holder having a first surface, wherein said sheet separating pad is disposed on said first surface of said sheet separating holder;   a resilient element disposed in the vicinity of said sheet separating holder and sustained against or coupled to said sheet separating holder, so that said sheet separating pad disposed on said sheet separating holder is urged against the sheet separating roller by said resilient element; and   a noise suppressing element arranged on said sheet separating holder for altering the natural frequency dynamic response of an assembly of said sheet separating pad and said sheet separating holder, thereby shifting the natural frequency dynamic response of said assembly of said sheet separating pad and said sheet separating holder from the working frequency and the harmonic frequency of said sheet separating roller.   
     
     
         2 . The sheet separating device according to  claim 1  wherein said sheet separating holder further comprises a second face opposed to said first surface, and said resilient element is sustained against or coupled to said second surface of said sheet separating holder. 
     
     
         3 . The sheet separating device according to  claim 2  wherein said noise suppressing element is a metallic block disposed on said second surface of said sheet separating holder for increasing the weight of said assembly of said sheet separating pad and said sheet separating holder, thereby shifting the natural frequency dynamic response of said assembly of said sheet separating pad and said sheet separating holder from the working frequency and the harmonic frequency of said sheet separating roller. 
     
     
         4 . The sheet separating device according to  claim 3  wherein said noise suppressing element is fixed on said second surface of said sheet separating holder by a screw. 
     
     
         5 . The sheet separating device according to  claim 1  wherein said noise suppressing element includes one or more perforations formed in said sheet separating holder for reducing the weight of said assembly of said sheet separating pad and said sheet separating holder, thereby shifting the natural frequency dynamic response of said assembly of said sheet separating pad and said sheet separating holder from the working frequency and the harmonic frequency of said sheet separating roller. 
     
     
         6 . The sheet separating device according to  claim 1  wherein said sheet separating roller has a first frictional layer, and said sheet separating pad has a frictional surface in contact with said first frictional layer of said sheet separating roller or a paper sheet that is transported between said first frictional layer of said sheet separating roller and said frictional surface of said sheet separating pad. 
     
     
         7 . The sheet separating device according to  claim 6  wherein the friction force between said first frictional layer of said sheet separating roller and said paper sheet is greater than the friction force between said frictional surface of the sheet separating pad and said paper sheet, and the friction force between said frictional surface of the sheet separating pad and said paper sheet is greater than the friction force between adjacent papers. 
     
     
         8 . The sheet separating device according to  claim 1  wherein said sheet separating pad is made of a material selected from a group consisting of silicon, polyurethane (PU) rubber, ethylene propylene diene (EPDM) rubber and nitrile butadiene rubber (NBR). 
     
     
         9 . The sheet separating device according to  claim 1  wherein said sheet separating holder is made of an insulating material. 
     
     
         10 . The sheet separating device according to  claim 1  wherein said sheet separating pad is fixed on said first surface of said sheet separating holder by adhesive, screwing means, clamping means or fastening means. 
     
     
         11 . The sheet separating device according to  claim 1  wherein an axle is protruded from bilateral sides of an edge of said sheet separating holder and two supporting elements are extended downwardly from bilateral sides of another edge of said sheet separating holder. 
     
     
         12 . The sheet separating device according to  claim 1  wherein said resilient element is a spring. 
     
     
         13 . The sheet separating device according to  claim 1  further comprising a sheet separation film, which is partially attached on said sheet separating pad. 
     
     
         14 . The sheet separating device according to  claim 13  wherein said sheet separation film is made of poly(ethylene terephthalate). 
     
     
         15 . An auto document feeder comprising:
 a sheet feeding device comprising a sheet pick-up roller and a sheet separating roller for successively transporting paper sheets into a sheet-guiding path; and   a sheet separating device comprising:
 a sheet separating pad arranged in said sheet-guiding path and facing said sheet separating roller, and cooperating with said sheet separating roller to separate a paper sheet fed into said sheet-guiding path; 
 a sheet separating holder having a first surface, wherein said sheet separating pad is disposed on said first surface of said sheet separating holder; 
 a resilient element disposed in the vicinity of said sheet separating holder and sustained against or coupled to said sheet separating holder, so that said sheet separating pad disposed on said sheet separating holder is urged against the sheet separating roller by said resilient element; and 
 a noise suppressing element arranged on said sheet separating holder for altering the natural frequency dynamic response of an assembly of said sheet separating pad and said sheet separating holder, thereby shifting the natural frequency dynamic response of said assembly of said sheet separating pad and said sheet separating holder from the working frequency and the harmonic frequency of said sheet separating roller. 
   
     
     
         16 . A fabricating process of a sheet separating device of an auto document feeder, said auto document feeder including a sheet separating roller, said fabricating process comprising steps:
 obtaining the working frequency and the harmonic frequency of said sheet separating roller;   providing a sheet separating pad and a sheet separating holder; and   adjusting or altering the overall weight of an assembly of said sheet separating pad and said sheet separating holder by a noise suppressing element according to the working frequency and the harmonic frequency of said sheet separating roller, thereby changing the natural frequency dynamic response of said assembly of said sheet separating pad and said sheet separating holder and shifting the natural frequency dynamic response of said assembly of said sheet separating pad and said sheet separating holder from the working frequency and the harmonic frequency of said sheet separating roller.   
     
     
         17 . The fabricating process according to  claim 16  wherein said noise suppressing element is a metallic block and said step of adjusting or altering the overall weight of said assembly of said sheet separating pad and said sheet separating holder by said noise suppressing element includes mounting said metallic block on said second surface of said sheet separating holder for increasing the overall weight of said assembly of said sheet separating pad and said sheet separating holder. 
     
     
         18 . The fabricating process according to  claim 16  wherein said noise suppressing element includes one or more perforations and said step of adjusting or altering the overall weight of said assembly of said sheet separating pad and said sheet separating holder by said noise suppressing element includes forming said one or more perforations in said sheet separating holder for reducing the overall weight of said assembly of said sheet separating pad and said sheet separating holder.