Device for driving an endless belt and image forming apparatus using the same

Abstract

A device for driving an endless belt of the present invention includes a drive roller and a roller pair adjoining the drive roller at a side where a photoconductive element is positioned and contacting the belt. The eccentricity of the drive roller and that of the roller pair are reduced to reduce the variation of belt speed when the drive roller is controlled at a preselected angular velocity. Even when the drum is eccentric, the device stably operates integrally with the belt without any slip or oscillation.

1 - 40 . (canceled)  
   
   
       41 . A method for driving an endless belt, comprising: 
 positioning a first roller at one end of the endless belt to drive the endless belt;    arranging at least one rotary body side by side in a direction of movement of the belt;    pressing said at least one rotary body against said belt either directly or indirectly to rotate said at least one rotary body with said belt;    positioning a second roller adjoining said first roller, said second roller contacting the belt at a side where said rotary body is positioned;    reducing an allowable eccentricity of each of said first roller and said second roller to a range that does not affect a variation of a speed of the belt.    
   
   
       42 . The method as claimed in  claim 41 , further comprising: 
 providing a motor to drive the first roller.    
   
   
       43 . The method as claimed in  claim 42 , further comprising: 
 integrally setting up a dynamic balance on a rotary portion of said motor and said first roller.    
   
   
       44 . The method as claimed in  claim 43 , further comprising: 
 integrally molding said first roller and a shaft of said first roller with each other.    
   
   
       45 . The method as claimed in  claim 42 , further comprising: 
 adjusting an eccentricity of at least one of said first roller and said second roller with an eccentricity adjusting mechanism assigned to at least one of said first roller and said second roller.    
   
   
       46 . The method as claimed in  claim 45 , further comprising: 
 integrally setting up a dynamic balance on a rotary portion of said motor and said first roller.    
   
   
       47 . The method as claimed in  claim 46 , further comprising: 
 integrally molding said first roller and a shaft of said first roller with each other.    
   
   
       48 . A method for driving an endless belt, comprising: 
 positioning belt driving means at one end of the belt, said belt driving means comprising a motor and a drive roller configured to move said belt;    arranging at least one rotary body side by side in a direction of movement of the belt;    pressing said at least one rotary body against said belt either directly or indirectly to rotate said at least one rotary body with said belt;    positioning a stationary guide body adjoining said drive roller and continuously contacting the belt at a side where said rotary body is positioned;    reducing an allowable eccentricity of said drive roller to a range that does not affect a variation of speed of the belt; and    integrally setting up a dynamic balance on a rotary portion of said motor and said drive roller.    
   
   
       49 . A method for driving an endless belt, comprising: 
 positioning belt driving means at one end of the belt, said belt driving means comprising a motor and a drive roller for moving said belt;    arranging at least one rotary body side by side in a direction of movement of the belt;    pressing said at least one rotary body against said belt either directly or indirectly to rotate said at least one rotary body with said belt;    positioning a stationary guide body adjoining said drive roller and continuously contacting the belt at a side where said rotary body is positioned;    reducing an allowable eccentricity of said drive roller to a range that does not affect a variation of speed of the belt;    integrally molding said drive roller and a shaft of said drive roller with each other; and    integrally setting up a dynamic balance on a rotary portion of said motor and said drive roller.    
   
   
       50 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt;    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate said at least one photoconductive drum with said belt; and    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor.    
   
   
       51 . The method as claimed in  claim 50 , further comprising setting torque ripples generated by said outer rotor coreless motor at a spatial frequency close to a maximum value in an allowable, torque ripple spatial frequency range at a low frequency side, which does not affect image quality.  
   
   
       52 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt;    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate said at least one photoconductive drum with said belt;    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor; and    setting torque ripples generated by said outer rotor coreless motor at a spatial frequency close to a maximum value in an allowable, torque ripple spatial frequency range at a low frequency side, which does not affect image quality,    wherein said outer rotor coreless motor comprises an outer rotor functioning as said drive roller at a same time.    
   
   
       53 . The method as claimed in  claim 52 , wherein the outer rotor comprises an encoder disk on which is at least one of timing marks for sensing a signal for rotation control and a mark for sensing a signal that switches a phase of a current to be fed to each of different coil phases.  
   
   
       54 . The method as claimed in  claim 53 , wherein said mark functions as a mark for sensing a start signal output for each rotation at a same time.  
   
   
       55 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt;    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate said at least one photoconductive drum with said belt;    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor; and    setting torque ripples generated by said outer rotor coreless motor at a spatial frequency close to a maximum value in an allowable, torque ripple spatial frequency range at a low frequency side, which does not affect image quality,    wherein said outer rotor coreless motor comprises an outer rotor that is formed integrally with said drive roller.    
   
   
       56 . The method as claimed in  claim 55 , wherein the outer rotor comprises an encoder disk on which is at least one of timing marks for sensing a signal for rotation control and a mark for sensing a signal that switches a phase of a current to be fed to each of different coil phases.  
   
   
       57 . The method as claimed in  claim 56 , wherein said mark functions as a mark for sensing a start signal output for each rotation at a same time.  
   
   
       58 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt;    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate said at least one photoconductive drum with said belt;    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor;    setting torque ripples generated by said outer rotor coreless motor at a spatial frequency close to a maximum value in an allowable, torque ripple spatial frequency range at a low frequency side, which does not affect image quality; and    driving said outer rotor coreless motor such that timings for feeding currents to coils of different phases substantially do not overlap each other when a flux density of a bore magnetic field is substantially constant.    
   
   
       59 . The method as claimed in  claim 58 , wherein the outer rotor comprises an encoder disk on which is at least one of timing marks for sensing a signal for rotation control and a mark for sensing a signal that switches a phase of a current to be fed to each of different coil phases.  
   
   
       60 . The method as claimed in  claim 59 , wherein said mark functions as a mark for sensing a start signal output for each rotation at a same time.  
   
   
       61 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt; and    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate said at least one photoconductive drum with said belt;    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor; and    setting torque ripples generated by said outer rotor coreless motor at a spatial frequency close to a maximum value in an allowable, torque ripple spatial frequency range at a low frequency side, which does not affect image quality,    wherein the outer rotor comprises an encoder disk on which is at least one of timing marks for sensing a signal for rotation control and a mark for sensing a signal that switches a phase of a current to be fed to each of different coil phases.    
   
   
       62 . The method as claimed in  claim 61 , wherein said mark functions as a mark for sensing a start signal output for each rotation at a same time.  
   
   
       63 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt;    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate at least one photoconductive drum with said belt; and    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor,    wherein said outer rotor coreless motor comprises an outer rotor functioning as said drive roller at a same time.    
   
   
       64 . The method as claimed in  claim 63 , wherein the outer rotor comprises an encoder disk on which is at least one of timing marks for sensing a signal for rotation control and a mark for sensing a signal that switches a phase of a current to be fed to each of different coil phases.  
   
   
       65 . The method as claimed in  claim 64 , wherein said mark functions as a mark for sensing a start signal output for each rotation at a same time.  
   
   
       66 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt;    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate said at least one photoconductive drum with said belt; and    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor,    wherein said outer rotor coreless motor comprises an outer rotor that is formed integrally with said drive roller.    
   
   
       67 . The method as claimed in  claim 66 , wherein the outer rotor comprises an encoder disk on which is at least one of timing marks for sensing a signal for rotation control and a mark for sensing a signal that switches a phase of a current to be fed to each of different coil phases.  
   
   
       68 . The method as claimed in  claim 67 , wherein said mark functions as a mark for sensing a start signal output for each rotation at a same time.  
   
   
       69 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt; and    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate said at least one photoconductive drum with said belt;    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor; and    driving said outer rotor coreless motor such that timings for feeding currents to coils of different phases substantially do not overlap each other when a flux density of a magnetic field is substantially constant.    
   
   
       70 . The method as claimed in  claim 68 , wherein the outer rotor comprises an encoder disk on which is at least one of timing marks for sensing a signal for rotation control and a mark for sensing a signal that switches a phase of a current to be fed to each of different coil phases.  
   
   
       71 . The method as claimed in  claim 69 , wherein said outer rotor coreless motor comprises an outer rotor that is formed integrally with said drive roller.  
   
   
       72 . The method as claimed in  claim 70 , wherein said mark functions as a mark for sensing a start signal output for each rotation at a same time.  
   
   
       73 . A method comprising: 
 positioning belt driving means at one end of an endless belt, which is one of at least an intermediate image transfer belt and a sheet conveying belt, said belt driving means comprising a drive roller for moving said belt;    arranging at least one photoconductive drum side by side in a direction of movement of the belt;    pressing said at least one photoconductive drum against said belt either directly or indirectly to rotate said at least one photoconductive drum with said belt; and    directly driving at least one of said drive roller and said photoconductive drum with an outer rotor coreless motor,    wherein the outer rotor comprises an encoder disk on which is at least one of timing marks for sensing a signal for rotation control and a mark for sensing a signal that switches a phase of a current to be fed to each of different coil phases.    
   
   
       74 . The apparatus as claimed in  claim 73 , wherein said mark functions as a mark for sensing a start signal output for each rotation at a same time.