Image forming apparatus

Abstract

In accordance with an embodiment, an image forming apparatus comprises a paper feed cassette configured to be capable of stacking and housing an envelope; a pickup roller configured to pick up the envelope from the paper feed cassette; a paper feed roller pair configured in a direction orthogonal to the conveyance direction of the envelope picked up by the pickup roller to convey the envelope with nipping the center area of the envelope; and a pressing roller pair configured in a direction orthogonal to the conveyance direction of the paper feed roller pair adjacent to the paper feed roller pair to convey the envelope with nipping the flap of the envelope, wherein the conveyance force applied to the envelope by the pressing roller pair is weaker than the conveyance force applied to the envelope by the paper feed roller pair.

1 . An image forming apparatus, comprising:
 a paper feed cassette configured to be capable of stacking and housing an envelope with a flap;   a pickup roller configured to pick up the envelope from the paper feed cassette;   a paper feed roller pair configured in a direction orthogonal to the conveyance direction of the envelope picked up by the pickup roller to convey the envelope with nipping the envelope; and   a pressing roller pair configured in a direction orthogonal to the conveyance direction of the paper feed roller pair adjacent to the paper feed roller pair to convey the envelope with nipping the flap of the envelope, the diameter of the pressing rollers is also set to be smaller than the diameter of the paper feed rollers.   
     
     
         2 . The apparatus of  claim 1 ,
 the paper feed roller pair is mounted on rotary shafts that are arranged to be parallel to each other in a direction orthogonal to the conveyance direction of the envelope picked up by the pickup roller; and   the pressing roller pair is arranged at a position corresponding to the flap on the rotary shafts adjacent to the paper feed roller pair.   
     
     
         3 . The apparatus of  claim 1 ,
 since the conveyance force applied to the envelope by the pressing rollers is smaller than the conveyance force applied by the paper feed rollers, the force used to nip the envelope by the pressing rollers is also set to be smaller than the force used to nip the envelope by the paper feed rollers.   
     
     
         4 . (canceled) 
     
     
         5 . The apparatus of  claim 1 ,
 the paper feed rollers include a separation roller for separating only one envelope to feed it to the subsequent stage when a plurality of envelopes is picked up by the pickup roller.   
     
     
         6 . The apparatus of  claim 1 , further comprising:
 a driving source configured to drive each of the paper feed rollers and the pressing rollers to rotate and stop synchronously.   
     
     
         7 . An image forming apparatus, comprising:
 a paper feed cassette capable of housing an envelope with a flap;   a pickup roller configured to pick up the envelope from the paper feed cassette;   paper feed rollers configured to be respectively mounted on rotary shafts that are arranged to be parallel to each other in a direction orthogonal to the conveyance direction of the envelope picked up by the pickup roller to convey the envelope to a subsequent stage with nipping the envelope;   pressing rollers configured to be respectively mounted on the rotary shafts adjacent to the paper feed rollers to convey the envelope with nipping the flap of the envelope, the diameter of the pressing rollers is also set to be smaller than the diameter of the paper feed rollers;   a conveyance roller configured to convey the envelope conveyed by the paper feed rollers and the pressing rollers to a transfer device; and   a fixing device configured to fix an image transferred by the transfer device on the envelope.   
     
     
         8 . The apparatus of  claim 7 ,
 since the conveyance force applied to the envelope by the pressing rollers is smaller than the conveyance force applied by the paper feed rollers, the force used to nip the envelope by the pressing rollers is also set to be smaller than the force used to nip the envelope by the paper feed rollers.   
     
     
         9 . (canceled) 
     
     
         10 . The apparatus of  claim 7 , further comprising:
 a driving source configured to drive each of the paper feed rollers and the pressing rollers to rotate and stop synchronously.   
     
     
         11 . The apparatus of  claim 7 , the pressing rollers and the paper feed rollers use materials having different friction coefficients.