Image forming system

Abstract

An image recording apparatus for recording an image on a sheet by a main scanning with a laser beam and a sub-scanning of the sheet, the image recording apparatus having: a pair of upstream rollers, arranged upstream of an exposing position of the laser beam; a pair of downstream rollers, wherein the sub-scanning is conducted by nipping and conveying the sheet with the pairs of upstream rollers and downstream rollers; wherein the pair of downstream rollers includes: a first roller driven by a drive section; a second roller, having a total weight of 300 g or less, wherein a gap amount of a nip between the first and the second rollers is set smaller than a thickness of the sheet; and a roller holding section for holding both ends of the second roller so as to be capable of driven rotation.

1 . An image recording apparatus for recording an image on a sheet by conducting a main scanning of the sheet with a laser beam while conducting a sub-scanning of the sheet, the image recording apparatus comprising: 
 a pair of upstream rollers, arranged upstream of an exposing position of the laser beam;    a pair of downstream rollers, arranged downstream of the exposing position of the laser beam, wherein the sub-scanning is conducted by nipping and conveying the sheet with the pair of upstream rollers and the pair of downstream rollers; wherein the pair of downstream rollers comprises:    a first roller driven by a drive section;    a second roller, having a total weight of 300 g or less, capable of carrying the sheet by nipping the sheet in cooperation with the first roller, wherein a gap amount of a nip between the first roller and the second roller is set smaller than a thickness of the sheet; and    a roller holding section for holding both ends of the second roller in such a manner as to be capable of driven rotation.    
   
   
       2 . The image recording apparatus of  claim 1 , further comprising an adjuster for adjusting the gap amount of the nip, the adjuster comprising a biasing section for biasing to an opposite direction of a gravity component of the second roller, the gravity component working on the first roller side, wherein adjuster is capable to adjust the gap amount of the nip by using the biasing section.  
   
   
       3 . The image recording apparatus of  claim 1 , further comprising a nip pressure controller for changing a nip pressure between the first roller and the second roller.  
   
   
       4 . The image recording apparatus of  claim 3 , wherein the nip pressure controller controls to increase the nip pressure a predetermined time after the leading edge of the sheet has entered in the nip of the pair of downstream rollers.  
   
   
       5 . The image recording apparatus of  claim 3 , wherein the nip pressure controller comprises a rotary solenoid, and the rotary solenoid is gradually moved under a pulse width modulation control.  
   
   
       6 . An image recording apparatus for recording an image on a sheet by conducting a main scanning of the sheet with a laser beam while conducting a sub-scanning of the sheet, the image recording apparatus comprising: 
 a pair of upstream rollers, arranged upstream of an exposing position of the laser beam;    a pair of downstream rollers, arranged downstream of the exposing position of the laser beam, wherein the sub-scanning is conducted by nipping and conveying the sheet with the pair of upstream rollers and the pair of downstream rollers; wherein the pair of downstream rollers comprises:    a first roller driven by a drive section;    a second roller, having a starting torque of 1.7 gf·cm or less, capable of carrying the sheet by nipping the sheet in cooperation with the first roller, wherein a gap amount of a nip between the first roller and the second roller is set smaller than a thickness of the sheet; and    a roller holding section for holding both ends of the second roller in such a manner as to be capable of driven rotation.    
   
   
       7 . The image recording apparatus of  claim 6 , further comprising an adjuster for adjusting the gap amount of the nip, the adjuster comprising a biasing section for biasing to an opposite direction of gravity component of the second roller, the gravity component working on the first roller side, wherein the adjuster is capable to adjust the gap amount of the nip by using the biasing section.  
   
   
       8 . The image recording apparatus of  claim 6 , further comprising a nip pressure controller for changing a nip pressure between the first roller and the second roller.  
   
   
       9 . The image recording apparatus of  claim 8 , wherein the nip pressure controller controls to increase the nip pressure a predetermined time after the leading edge of the sheet has entered in the nip of the pair of downstream rollers.  
   
   
       10 . The image recording apparatus of  claim 8 , wherein the nip pressure controller comprises a rotary solenoid, and the rotary solenoid is gradually moved under a pulse width modulation control.