Typewriting machines – Sheet or web – Including skew correction responsive to position of sheet or...
Reexamination Certificate
2000-11-17
2003-01-28
Hirshfeld, Andrew H. (Department: 2854)
Typewriting machines
Sheet or web
Including skew correction responsive to position of sheet or...
C400S578000, C399S394000, C347S129000, C271S002000, C250S208100
Reexamination Certificate
active
06511239
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to office equipment such as printers and copiers, and in particular relates to a system for detecting and eliminating flyers, which are sheets deviating from the designed side edge position in a center or side registered paper path system.
BACKGROUND OF THE INVENTION
Office equipment, such as printers and copiers, which place images based on digital data onto sheets, such as sheets of paper, are well known. More sophisticated types of office equipment are capable of placing images on both sides of a single sheet of paper, a feature often referred to as “duplexing.” A typical configuration of a duplexing printer (the word “printer” including other types of equipment, such as digital copiers and facsimile machines) will include a marking device, meaning some hardware which places a desired image on a sheet, which is capable of printing only on one side of the sheet at a time. In order to print on both sides of the same sheet, it is necessary to feed a sheet through the marking device the first time, so the sheet can receive a first image on one side thereof, and then invert the sheet and re-feed it back into the marking device so that the marking device can place a second image on the other side of the sheet. Although the specific architectures of various office equipment on the market varies widely, the path (along with any associated sheet-handling hardware, such as belts or rollers and motors) by which a sheet which has been output by the marking device is inverted and re-fed to the marking device can be generally referred to as a “duplex path. ”
To properly place an image onto sheets, the sheets must be precisely registered. Occasionally in a center or side registered paper path system, a sheet will stray from the designed side edge position in the path. The undesirable result of these “flyers” is side edge mis-registration of the image on the sheet. Historically, the approach has been to improve the paper path performance in an attempt to prevent the “flyers”. Unfortunately, not all outside influences can be designed out of the system. As a result, flyers continue to occur and cause customer dissatisfaction with side edge registration. Therefore, there is a need to eliminate the flyers caused by outside influences.
SUMMARY OF THE INVENTION
In one embodiment of the present invention, a printing apparatus includes a marking device, the marking device being capable of placing images on sheets fed therein, and outputting the sheets; a feed path, by which sheets are fed from a sheet supply to the marking device; a first sensor, outputting a first position signal relating to a location of a side edge as each sheet passes through the feed path; and an image placement controller associated with the marking device, the image placement controller determining whether each sheet is a flyer based on the first position signal. The marking device includes a charge receptor or an ink-jet printhead. The printing apparatus further includes a duplex path, by which sheets output from the marking device are re-fed to the marking device; and a second sensor, outputting a second position signal relating to a location of a side edge as each sheet passes through the duplex path, wherein the image placement controller associated with the marking device determines whether a sheet is a flyer based on at least one of the first position signal and second position signal.
The printing apparatus includes a marking device, the marking device being capable of placing an image on a sheet fed therein, and outputting the sheet; a feed path, by which sheets are fed from a sheet supply to the marking device; a duplex path, by which sheets output from the marking device are re-fed to the marking device; a first sensor, outputting a first position signal relating to a location of a side edge as each sheet passes through the feed path; a second sensor, outputting a second position signal relating to a location of a side edge as each sheet passes through the duplex path; and an image placement controller associated with the marking device, the image placement controller retaining first position signals for a plurality of sheets passing through the feed path and second position signals for a plurality of sheets passing through the duplex path, and calculating new average paper positions for each sheet in response to at least one of the first position signals and the second position signals. The new average paper position of each sheet is calculated based on whether the sheet is a flyer or the preceding sheet is a flyer. The marking device includes a charge receptor or ink-jet printhead.
A method for determining and eliminating flyers in a printing apparatus, including measuring each sheet position at a first sensor, wherein the first sensor outputs first position signal to a controller; determining sheet position and sheet variance based on first position signal; comparing sheet variance to a running average sheet variance to determine whether the sheet is a flyer; and calculating new average sheet position based on said comparison for marking images on sheets. The method for determining and eliminating flyers in a printing apparatus, further includes measuring each sheet position at a second sheet sensor, wherein the second sensor outputs second position signal to the controller; determining sheet shift position and sheet shift variance based on first position signal and second position signal; comparing sheet shift variance to a running average sheet shift variance to determine whether the sheet is a flyer; and calculating new average sheet shift position based on said comparison for marking images on sheets.
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Brutovski Robert
Kretschmann Deborah M.
Thomas Dean
Yang Ming
Crenshaw Marvin P
Daebeler Paul F.
Eipert William F.
Hirshfeld Andrew H.
Xerox Corporation
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