Browse Prior Art Database

Skew Detection

IP.com Disclosure Number: IPCOM000119692D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 73K

Publishing Venue

IBM

Related People

Dodt, WC: AUTHOR [+2]

Abstract

The skew detection described herein occurs after the image is placed on the sheet of paper. As shown in the figure, there are three types of skew conditions -- ideal, unacceptable and dynamic -- that are of importance when working with information or images printed on paper of the cut-sheet format.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 63% of the total text.

Skew Detection

      The skew detection described herein occurs after the
image is placed on the sheet of paper.  As shown in the figure, there
are three types of skew conditions -- ideal, unacceptable and dynamic
-- that are of importance when working with information or images
printed on paper of the cut-sheet format.

      The ideal skew condition is shown in Detail A.  Two
requirements for printing in the ideal skew environment are:
      1.   The printhead would have to be perfectly square with the
paper path.
      2.   Each sheet of paper would have to be moved and handled so
that the edge of the paper is parallel to the printhead.

      These two conditions vary from machine to machine.

      Unacceptable skew condition, Detail B, is severe enough that
part of the image or data is actually printed off the sheet,
resulting in lost information.

      Detection of a skew condition is accomplished by the time delay
between the leading edge of the paper passing over sensors A and B
which is compared to a preset limit. When the time delay exceeds the
preset limit, an error condition exists and the printer stops,
indicating a paper jam so that the skewed sheet can be removed.  The
print job can then be restarted using standard system error recovery
procedures.

      Dynamic skew, shown in Detail C, is the skew inherent in the
paper path.  The image is aligned, but the sheet is skewed to the
paper path.  This inherent skew is...