Image forming method

Details Image forming method Image forming method

1999-04-27

2002-06-04

Grant, II, Jerome (Department: 2624)

Facsimile and static presentation processing

Static presentation processing

C358S001900, C358S001140

Reexamination Certificate

active

06400461

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to an image forming method for a copying machine using an automatic document feeder and double face printer, for example.
In recent years, in an image forming apparatus, an attempt is made to shorten time for printing paper to reach the printing position and enhance the copying speed by feeding printing paper at the same time as feeding of a document in a case where an automatic document feeder (ADF) is used to effect the continuous copying operation.
In this case, if a document jam occurs during the document feeding process by use of the ADF and normal image reading cannot be attained, printing paper which is already started to be fed is also jammed if it is stopped at the place. Therefore, the printing paper is discharged as a failure in printing in order to prevent the paper jam.
At this time, the document fed is not placed in the normal position. Therefore, if a scanned image is output, there occurs a possibility that an image is only partly printed on the printing paper or an image of the preceding document is printed on the printing paper. In order to prevent the user from being disturbed, the image is not output, only the paper is fed and, as a result, a blank sheet of paper is obtained. Therefore, in the specified discharging destination, one or more blank sheets of paper are discharged.
When double face printing is effected by use of a double face printer (perfecting machine) and if blank printing occurs by a document jam or the like, paper printed in the blank state is stacked (stored) in the double face printer. As the result, since one page of blank paper is inserted, the normal relation between the pages on the front and rear surfaces cannot be obtained.
For example, in a case where one set of documents including single-face documents of six pages are printed on printing paper by double face printing by use of a copying machine having no memory for storing read images, the documents are printed with the first page/second page, third page/fourth page, fifth page/sixth page printed on the front/rear surfaces of respective sheets of printing paper as shown at (a) to (c) in
FIG. 25
if the normal printing is effected.
If the document of third page is jammed to cause abnormal paper feeding and a failure in reading of the document occurs, the first page/second page, abnormal image (blank paper)/third page, fourth page/fifth page, sixth page/blank page are obtained on the front/rear surfaces of respective sheets of printing paper as shown at (a) to (d) in FIG.
26
. Therefore, in comparison with the printing result of the correct double-face printing, the relation between the pages on the front and rear surfaces is reversed before and after the page of abnormal image (blank paper). This also occurs when double-face documents are printed by double face printing.
Further, in the case of a digital copying machine having a memory for storing read images, images of the documents read by a scanner section can be temporarily stored and held in the memory. Therefore, it is possible to print the images in an order different from the reading order in which the images are read by the scanner section
4
. Further, the images stored in the memory can be printed after all of the documents are read. However, in this case, it is necessary to substantially simultaneously effect the paper feeding operation of a document, scanning operation and printing operation so as to enhance the copying speed.
In the digital copying machine of first-in first-out (FIFO) system having the above memory, for first feeding paper which is first stacked by the double face printer, the printing for the first page, third page and fifth page is effected in this order at the same time as reading of the documents when single-face documents of plural pages are printed by double face printing. In this case, images of the documents read are stored into the memory, and at the same time, sheets of paper on one-side surfaces of which images of odd pages of the first page, third page and fifth page are printed are stacked in the double face printer.
Then, the sheets of paper on one-side surfaces of which images of the first page, third page and fifth page are printed are sequentially fed out from the double face printer, document images of the second page, fourth page and sixth page are printed on the rear surfaces of the sheets of printing paper and the sheets of printing paper are discharged. As a result, the first page/second page, third page/fourth page, fifth page/sixth page are printed on the front/rear surfaces of the respective sheets of paper as shown at (a) to (c) in FIG.
25
.
Thus, wasting time caused by the mechanical structure is reduced and the copying speed is enhanced. In this system, if the document of third page is jammed to cause abnormal paper feeding and a failure in reading of the document occurs, images printed on the one-side surfaces of the sheets of paper stacked in the double face printer are the first page, abnormal image (blank paper), third page and fifth page, and if printing is made on the rear surfaces of the sheets of paper, the first page/second page, abnormal image (blank page)/fourth page, third page/sixth page, fifth page/blank page are obtained on the front/rear surfaces of the respective sheets of paper as shown at (a) to (d) in FIG.
27
. The same result may be obtained in the case of double-face document.
In a device of first-in last-out (FILO) system having a memory for storing images, for first feeding paper which is last stacked by the double face printer, document images are printed on the front surfaces of sheets of paper in an order of the second page, fourth page, sixth page of the documents and the sheets of paper are stacked on the double face printer. Then, document images are printed on the rear surfaces of the sheets of paper stacked in the double face printer in an order of the fifth page, third page and first page and the sheets of paper are discharged. As a result, the sixth page/fifth page, fourth page/third page, second page/first page are printed on the front/rear surfaces of the respective sheets of paper as shown at (a) to (c) in FIG.
28
.
In this case, if a failure in reading of the document of third page occurs, for example, images are printed on sheets of paper stacked in the double face printer in an order of the second page, abnormal image (blank paper), fourth page and sixth page. Then, if images are printed on the rear surfaces of the stacked sheets of paper, the sixth page/fifth page, abnormal image (blank paper)/third page, fourth page/first page, second page/blank paper are printed on the front/rear surfaces of the respective sheets of paper as shown at (a) to (d) in FIG.
29
and the relation between the pages on the front and rear surfaces becomes strange.
As described above, if a document jam occurs in the automatic document feeder when the double face printing is effected by use of the automatic document feeder, printing paper which is started to be fed at the same time is stacked in the double face printer with the surface thereof kept in a blank state. Since the paper stacked in the blank state is dealt with in the same manner as another sheet of paper which has been correctly printed and stacked when the printing for the rear surfaces thereof is started, the printing is made on the rear surface of the blank paper and the relation between the succeeding pages of the front and rear surfaces becomes strange.
BRIEF SUMMARY OF THE INVENTION
An object of this invention is to provide an image forming method for dealing with paper on which an erroneously read image is printed in the same manner as correctly printed paper when the double face printing is made and effecting the double face printing operation with the pages of the front and rear surfaces of sheets of paper set in order without shifting the pages of the front and rear surfaces of the sheets of paper.
According to one aspect of this invention there is provided an image forming method effected by use of an image forming apparatus inclu

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