Drive transmission device, sheet conveying device, and image forming apparatus

Abstract

A drive transmission device transmits a driving force of a drive source to conveyance rollers to convey a sheet, the conveyance rollers including: a relay conveyance roller upstream from a registration roller in a sheet conveyance direction to convey at least a sheet fed from a sheet feeding cassette toward the registration roller; and a bypass relay conveyance roller in a bypass relay path to convey a sheet fed from a bypass tray to a joining point where the sheet fed from the bypass tray joins into a conveyance path on which the sheet fed from the sheet feeding cassette is conveyed. The drive transmission device includes a drive transmission interrupter in a drive transmission path from the drive source to the relay conveyance roller to interrupt drive transmission. The driving force of the drive source is transmitted via the drive transmission interrupter to the bypass relay conveyance roller.

1 . A drive transmission device to transmit a driving force of a drive source to a plurality of conveyance rollers to convey a sheet, the plurality of conveyance rollers including: a relay conveyance roller upstream from a registration roller in a sheet conveyance direction to convey at least a sheet fed from a sheet feeding cassette toward the registration roller; and a bypass relay conveyance roller in a bypass relay path to convey a sheet fed from a bypass tray to a joining point where the sheet fed from the bypass tray joins into a conveyance path on which the sheet fed from the sheet feeding cassette is conveyed,
 the drive transmission device comprising:
 a drive transmission interrupter in a drive transmission path from the drive source to the relay conveyance roller to interrupt drive transmission in the drive transmission path, 
 wherein the driving force of the drive source is transmitted via the drive transmission interrupter to the bypass relay conveyance roller. 
   
     
     
         2 . The drive transmission device according to  claim 1 ,
 wherein the plurality of conveyance rollers further include a reverse conveyance roller on a reverse conveyance path through which a sheet having passed through a fixing device and been switchback-conveyed and is conveyed to the registration roller again, and   the driving force of the drive source is transmitted to the reverse conveyance roller via the drive transmission interrupter.   
     
     
         3 . The drive transmission device according to  claim 2 ,
 wherein the plurality of conveyance rollers further include a roller of a sheet feeder to feed a sheet from the sheet feeding cassette;   a roller of a bypass sheet feeder that feeds a sheet from the bypass tray; and   the registration roller.   
     
     
         4 . A sheet conveying device, comprising:
 a sheet feeder to feed a sheet from a sheet feeding cassette;   a bypass sheet feeder to feed a sheet from a bypass tray;   a registration roller;   a relay conveyance roller upstream from the registration roller to convey at least a sheet fed from the sheet feeding cassette toward the registration roller;   a bypass relay conveyance roller on a bypass relay path to convey a sheet fed from the bypass tray to a joining point where the sheet fed from the bypass tray joins into a conveyance path on which the sheet fed from the sheet feeding cassette is conveyed; and   a drive transmission device to transmit a driving force of a drive source to at least the relay conveyance roller and the bypass relay conveyance roller, the drive transmission device including a drive transmission interrupter on a drive transmission path from the drive source to the relay conveyance roller to interrupt drive transmission,   wherein the driving force of the drive source is transmitted to the bypass relay conveyance roller via the drive transmission interrupter.   
     
     
         5 . An image forming apparatus, comprising:
 the sheet conveying device according to claim  4 ; and   an image forming device to form an image on a sheet conveyed by the sheet conveying device.   
     
     
         6 . The image forming apparatus according to  claim 5 , further comprising:
 a latent image bearer; and   a latent image writing device to write a latent image on the latent image bearer,   wherein the bypass relay path is directly below the latent image writing device.