Apparatus and method for controlling recording and sheet conveying based on recording scans and sheet position

Abstract

A recording apparatus for forming images using a recording head includes a feeding roller, a conveying roller, a conveyance control unit, and a recording control unit. The conveyance control unit performs a conveying operation a number of times after the trailing end of a sheet reaches a predetermined position defined between the feeding roller and the conveying roller such that the trailing end of the sheet is disposed in a predetermined range upstream of the conveying roller in a sheet conveying direction after the conveying operations. At least one of the conveying operations performed a number of times is performed based on a distance from the position of the trailing end of the sheet to the position of the conveying roller.

What is claimed is: 
     
       1. A recording apparatus for forming images using a recording head scanning over a predetermined area on a sheet N times, the recording apparatus comprising:
 a feeding roller configured to convey the sheet disposed on a stacking unit;   a conveying roller configured to further convey the sheet fed by the feeding roller;   a conveyance control unit configured to control drive of the conveying roller each time scanning is performed by the recording head; and   a recording control unit configured to control a first recording in which the scanning is performed N times by selecting recording elements of the recording head until a trailing end of the sheet reaches a predetermined position defined between the feeding roller and the conveying roller, and configured to control a second recording in which the scanning is performed N times using a part of the recording elements of the recording head after the trailing end of the sheet reaches the predetermined position,   wherein the conveyance control unit performs a conveying operation a number of times based on the value of N after the trailing end of the sheet reaches the predetermined position such that the trailing end of the sheet is disposed in a first range remote from and upstream of the conveying roller in a direction in which the sheet is conveyed after the conveying operations, and   wherein at least one of the conveying operations performed a number of times based on the value of N is performed based on a distance from a position of the trailing end of the sheet to the position of the conveying roller.   
     
     
       2. The recording apparatus according to  claim 1 , further comprising a detection unit disposed between the feeding roller and the conveying roller on a conveying path and configured to detect the trailing end of the sheet. 
     
     
       3. The recording apparatus according to  claim 1 , wherein the trailing end of the sheet is conveyed to a second range downstream of the conveying roller in the direction in which the sheet is conveyed by a conveying operation performed after the trailing end of the sheet is disposed in the first range. 
     
     
       4. A method for controlling a recording apparatus for forming images using a recording head scanning over a predetermined area on a sheet N times, the recording apparatus including a feeding roller configured to convey the sheet disposed on a stacking unit and a conveying roller configured to further convey the sheet fed by the feeding roller, the method comprising:
 controlling drive of the conveying roller each time scanning is performed by the recording head; and   controlling a first recording in which the scanning is performed N times by selecting recording elements of the recording head until a trailing end of the sheet reaches a predetermined position defined between the feeding roller and the conveying roller, and controlling a second recording in which the scanning is performed N times using a part of the recording elements of the recording head after the trailing end of the sheet reaches the predetermined position,   wherein the drive of the conveying roller is controlled so as to perform a conveying operation a number of times based on the value of N after the trailing end of the sheet reaches the predetermined position such that the trailing end of the sheet is disposed in a first range including the position of the conveying roller and upstream of the conveying roller in a direction in which the sheet is conveyed after the conveying operations, and   wherein at least one of the conveying operations performed a number of times based on the value of N is performed based on a distance from a position of the trailing end of the sheet to the position of the conveying roller.   
     
     
       5. A recording apparatus comprising:
 a recording unit configured to form an image on a sheet;   a pair of rollers, providing a nip portion therebetween, configured to convey the sheet along a path;   a driving unit configured to drive one of the pair of rollers;   a detection unit configured to detect a trailing end of the sheet conveyed with the pair of rollers, and   a control unit configured to control the driving unit such that the sheet is conveyed by a plurality of conveying steps each having a predetermined conveyance distance and conveyed by one conveying step which causes the trailing end of the sheet to skip an unstable area, the unstable area including the nip portion,   wherein the control unit varies the predetermined conveyance distance for at least one of the plurality of the conveying steps based on a detection of the detection unit, so that the trailing end of the sheet conveyed by a last conveying step of the plurality of the conveying steps just before the one conveying step stops in an upstream portion of the path which lies adjacent to the unstable area and has a length shorter than the predetermined conveyance distance in a direction of the path.   
     
     
       6. The recording apparatus according to claim 5, wherein the control unit varies the predetermined conveyance amount based on a position of an upstream edge of the unstable area and information about the trailing end of the sheet detected by the detection unit. 
     
     
       7. The recording apparatus according to claim 5, wherein the control unit varies the predetermined conveyance amount based on a distance between the unstable area and a position of the trailing end of the sheet. 
     
     
       8. The recording apparatus according to claim 5, wherein a conveyance distance by the one conveying step to skip the unstable area is equal to or more than a sum of distances of the unstable area and the upstream portion along the path. 
     
     
       9. The recording apparatus according to claim 5, wherein the control unit varies the predetermined conveyance distance by selecting from a data table of a plurality of conveying distances. 
     
     
       10. The recording apparatus according to claim 5, wherein the unstable area lies both upstream and downstream of the nip portion along the path. 
     
     
       11. The recording apparatus according to claim 5, wherein the length of the unstable area is determined based on at least one of sizes, materials and positions of the pair of rollers, and thickness of the sheet. 
     
     
       12. The recording apparatus according to claim 5, wherein each of the conveying steps and recording of a part of the image with the recording unit are performed alternatively. 
     
     
       13. The recording apparatus according to claim 12, wherein the recording unit forms the part of the image having a width corresponding to the conveyance distance. 
     
     
       14. The recording apparatus according to claim 12, wherein the recording unit comprises a recording head, and a carriage mounting the recording head to reciprocate perpendicular to the direction of the path. 
     
     
       15. The recording apparatus according to claim 14, wherein the recording head is an inkjet type. 
     
     
       16. A sheet conveying apparatus comprising:
 a pair of rollers, providing a nip portion therebetween, configured to convey the sheet along a path;   a driving unit configured to drive one of the pair of rollers;   a detection unit configured to detect a trailing end of the sheet conveyed with the pair of rollers, and   a control unit configured to control the driving unit such that the sheet is conveyed by a plurality of conveying steps each having a predetermined conveyance distance and conveyed by one conveying step which causes the trailing end of the sheet to skip an unstable area, the unstable area including the nip portion,   wherein the control unit varies the predetermined conveyance distance for at least one of the plurality of the conveying steps based on a detection of the detection unit, so that the trailing end of the sheet conveyed by a last conveying step of the plurality of the conveying steps just before the one conveying step stops in an upstream portion of the path which lies adjacent to the unstable area and has a length shorter than the predetermined conveyance distance in a direction of the path.   
     
     
       17. The sheet conveying apparatus according to claim 16, wherein a conveyance distance by the one conveying step to skip the unstable area is equal to or more than a sum of distances of the unstable area and the upstream portion along the path. 
     
     
       18. The sheet conveying apparatus according to claim 16, wherein the control unit varies the predetermined conveyance distance by selecting from a data table of a plurality of conveying distances. 
     
     
       19. The sheet conveying apparatus according to claim 16, wherein the unstable area lies both upstream and downstream of the nip portion along the path. 
     
     
       20. The sheet conveying apparatus according to claim 16, wherein the length of the unstable area is determined based on at least one of sizes, materials and positions of the pair of rollers, and thickness of the sheet. 
     
     
       21. The sheet conveying apparatus according to claim 16, wherein the control unit varies the predetermined conveyance amount based on a position of an upstream edge of the unstable area and information about the trailing end of the sheet detected by the detection unit. 
     
     
       22. The sheet conveying apparatus according to claim 16, wherein the control unit varies the predetermined conveyance amount based on a distance between the unstable area and a position of the trailing end of the sheet. 
     
     
       23. An image forming apparatus configured to form an image on a sheet by conveying operations of the sheet and scanning operations of a recording head, the image forming apparatus comprising:
 a conveying roller configured to convey the sheet along a conveyance path;   a pinch roller configured to, with the conveying roller, pinch the sheet at a nip portion;   a driving unit configured to drive the conveying roller so that the sheet is conveyed toward an area, including the nip portion, of the conveyance path, by a first conveying amount per conveying operation of the sheet, wherein a trailing end of the sheet is conveyed, at one conveying operation, from a first stop position outside of the area to a second stop position outside of the area so that the trailing end of the sheet passes through the area along the conveyance path without stopping; and   a detection unit configured to detect the trailing end of the sheet, wherein the first conveying amount is varied to a second conveying amount after the detection unit has detected the trailing end of the sheet, and the sheet is conveyed by the second conveying amount before the one conveying operation which causes the trailing end of the sheet to stop at the second position so that a distance from the first stop position to an upstream edge of the area along the conveyance path is shorter than the first conveying amount.   
     
     
       24. The image forming apparatus according to claim 23, further comprising a controller configured to control the conveying amount. 
     
     
       25. The image forming apparatus according to claim 23, wherein the area includes regions of the conveyance path upstream and downstream of the nip portion. 
     
     
       26. The image forming apparatus according to claim 23, wherein the area is determined based on the conveying roller and the pinch roller. 
     
     
       27. The image forming apparatus according to claim 23, wherein the area is an unstable stop area. 
     
     
       28. The image forming apparatus according to claim 23, wherein there are at least three different conveying amounts after the detection unit has detected the trailing end of the sheet and before the trailing end of the sheet has passed through the area. 
     
     
       29. The image forming apparatus according to claim 23, wherein the second conveying amount is set based on a distance from a position of the upstream edge of the area to a position of the trailing end of the sheet. 
     
     
       30. The image forming apparatus according to claim 23, wherein the second conveying amount is set based on a table of conveying amounts. 
     
     
       31. The image forming apparatus according to claim 23, wherein the recording head comprises a plurality of recording elements, and
 wherein a number of the recording elements to be used for forming the image at the scanning operation is varied according to the conveying operation.   
     
     
       32. The image forming apparatus according to claim 23, wherein the sheet is conveyed by the second conveying amount and a plurality of the first conveying amounts after the trailing end of the sheet has reached a position and before the one conveying operation which causes the trailing end of the sheet to stop at the second position. 
     
     
       33. The image forming apparatus according to claim 23, wherein the second conveying amount is smaller than the first conveying amount. 
     
     
       34. The image forming apparatus according to claim 23, wherein the recording head comprises a plurality of recording elements, and a number of the recording elements to be used for forming the image at a scanning operation is varied after the trailing end of the sheet has been detected by the detection unit. 
     
     
       35. A recording apparatus for forming images using a recording head scanning over a predetermined area on a sheet N times, the recording apparatus comprising: a feeding roller configured to convey the sheet disposed on a stacking unit; a conveying roller configured to further convey the sheet fed by the feeding roller; a conveyance control unit configured to control drive of the conveying roller each time scanning is performed by the recording head; and a recording control unit configured to control a first recording in which the scanning is performed N times by selecting recording elements of the recording head until a trailing end of the sheet reaches a predetermined position defined between the feeding roller and the conveying roller, and configured to control a second recording in which the scanning is performed N times using a part of the recording elements of the recording head after the trailing end of the sheet reaches the predetermined position, wherein the conveyance control unit performs a conveying operation a number of times based on the value of N after the trailing end of the sheet reaches the predetermined position such that the trailing end of the sheet is disposed in a first range remote from and upstream of the conveying roller in a direction in which the sheet is conveyed after the conveying operations, and wherein at least one of the conveying operations performed a number of times based on the value of N is performed based on a distance from a position of the trailing end of the sheet to the position of the conveying roller. 
     
     
       36. The recording apparatus according to claim 35, further comprising a detection unit disposed between the feeding roller and the conveying roller on a conveying path and configured to detect the trailing end of the sheet. 
     
     
       37. The recording apparatus according to claim 35, wherein the trailing end of the sheet is conveyed to a second range downstream of the conveying roller in the direction in which the sheet is conveyed by a conveying operation performed after the trailing end of the sheet is disposed in the first range. 
     
     
       38. A method for controlling a recording apparatus for forming images using a recording head scanning over a predetermined area on a sheet N times, the recording apparatus including a feeding roller configured to convey the sheet disposed on a stacking unit and a conveying roller configured to further convey the sheet fed by the feeding roller, the method comprising: controlling drive of the conveying roller each time scanning is performed by the recording head; and controlling a first recording in which the scanning is performed N times by selecting recording elements of the recording head until a trailing end of the sheet reaches a predetermined position defined between the feeding roller and the conveying roller, and controlling a second recording in which the scanning is performed N times using a part of the recording elements of the recording head after the trailing end of the sheet reaches the predetermined position, wherein the drive of the conveying roller is controlled so as to perform a conveying operation a number of times based on the value of N after the trailing end of the sheet reaches the predetermined position such that the trailing end of the sheet is disposed in a first range including the position of the conveying roller and upstream of the conveying roller in a direction in which the sheet is conveyed after the conveying operations, and wherein at least one of the conveying operations performed a number of times based on the value of N is performed based on a distance from a position of the trailing end of the sheet to the position of the conveying roller.