Sheet conveying mechanism and image forming apparatus

Abstract

Disclosed is a sheet conveying mechanism, including: a sheet feeder that conveys a sheet to a sheet conveying path; a conveying track that defines the sheet conveying path of the sheet; and a conveying roller pair that conveys the sheet along the sheet conveying path. The sheet conveying mechanism further includes: a conveying track separator that adjusts a height of the sheet conveying path, wherein the sheet conveying path has at least a first height and a second height, and the second height is greater than the first height; and a conveying roller separator that adjusts a clamping force of the conveying roller pair, wherein the conveying roller pair has at least a first clamping force and a second clamping force, and the second clamping force is smaller than the first clamping force.

What is claimed is: 
     
         1 . A sheet conveying mechanism, comprising:
 a sheet feeder that conveys a sheet to a sheet conveying path;   a conveying track that defines the sheet conveying path of the sheet; and   a conveying roller pair that conveys the sheet along the sheet conveying path;   wherein the sheet conveying mechanism further comprises:   a conveying track separator that adjusts a height of the sheet conveying path, wherein the sheet conveying path has at least a first height and a second height, and the second height is greater than the first height; and   a conveying roller separator that adjusts a clamping force of the conveying roller pair, wherein the conveying roller pair has at least a first clamping force and a second clamping force, and the second clamping force is smaller than the first clamping force.   
     
     
         2 . The sheet conveying mechanism according to  claim 1 , wherein the sheet conveying mechanism further comprises:
 a hardware processor that has a sheet conveying mode and a sheet discharging mode, wherein in the sheet conveying mode, the sheet conveying path has the first height, and in the sheet discharging mode, the hardware processor switches the sheet conveying path from the first height to the second height.   
     
     
         3 . The sheet conveying mechanism according to  claim 2 , wherein in the sheet discharging mode, the hardware processor further determines whether to switch the sheet conveying path from the first height to the second height based on a conveying abnormality of the sheet. 
     
     
         4 . The sheet conveying mechanism according to  claim 2 , wherein in the sheet discharging mode, the hardware processor further determines whether to switch the sheet conveying path from the first height to the second height based on a sheet grammage of the sheet. 
     
     
         5 . The sheet conveying mechanism according to  claim 2 , wherein in the sheet conveying mode, before a front end of the sheet enters the conveying roller pair, the conveying roller pair has the first clamping force, when the front end of the sheet enters the conveying roller pair, the conveying roller pair has the second clamping force, and after the front end of the sheet enters the conveying roller pair, the conveying roller pair has the first clamping force, wherein in the sheet discharging mode, the conveying roller pair has the first clamping force. 
     
     
         6 . The sheet conveying mechanism according to  claim 2 , wherein the sheet conveying mechanism further comprises a sheet detector that detects the sheet, and the conveying roller pair comprises an upstream conveying roller pair and a downstream conveying roller pair located on two sides of the sheet detector, wherein in the sheet conveying mode, before a front end of the sheet enters the downstream conveying roller pair, the downstream conveying roller pair has the first clamping force, when the front end of the sheet enters the downstream conveying roller pair, the downstream conveying roller pair has the second clamping force, and after the front end of the sheet enters the downstream conveying roller pair, the downstream conveying roller pair has the first clamping force, before a rear end of the sheet leaves the upstream conveying roller pair, the upstream conveying roller pair has the first clamping force, when the rear end of the sheet leaves the upstream conveying roller pair, the upstream conveying roller pair has the second clamping force, and after the rear end of the sheet leaves the upstream conveying roller pair, the upstream conveying roller pair has the first clamping force, wherein in the sheet discharging mode, the upstream conveying roller pair and the downstream conveying roller pair both have the first clamping force. 
     
     
         7 . The sheet conveying mechanism according to  claim 6 , wherein when the front end of the sheet reaches a first predetermined position, the clamping force of the downstream conveying roller pair is adjusted by the conveying roller separator, and when the rear end of the sheet reaches a second predetermined position, the clamping force of the upstream conveying roller pair is adjusted by the conveying roller separator. 
     
     
         8 . The sheet conveying mechanism according to  claim 7 , wherein the sheet conveying mechanism further comprises a first detection sensor and a second detection sensor, wherein the first detection sensor detects whether the front end of the sheet has reached the first predetermined position, and the second detection sensor detects whether the rear end of the sheet has reached the second predetermined position. 
     
     
         9 . The sheet conveying mechanism according to  claim 1  wherein the conveying track separator comprises a first driving motor, a first driving belt and a first rotary cam, and the first driving motor drives the first rotary cam to rotate through the first driving belt to adjust the height of the sheet conveying path of the conveying track, and/or the conveying roller separator comprises a second driving motor, a second driving belt and a second rotary cam, and the second driving motor drives the second rotary cam to rotate through the second driving belt to adjust the clamping force of the conveying roller pair. 
     
     
         10 . An image forming apparatus, comprising:
 a sheet conveying mechanism according to  claim 1 , that conveys a sheet; and   an image former that forms an image on the sheet.