Paper skew detection system
AssigneeXerox Corporation
InventorHoward A Mizes
Life of this patent
Estimating the term…
Abstract
A system and method that enables web paper skew detection by monitoring print head motor position. An inline full width array sensor actively tracks the alignment of the print heads across the print zone and actively moves the heads to maintain alignment. If the paper starts to skew across the print zone, a color misregistration error will be detected and the print units will be moves with respect to each other to maintain alignment. The absolute position of the print heads can be monitored by tracking the steps sent to each motor to maintain alignment.
Claims20
A method for aligning print heads of a printer that deposit inks onto web paper, comprising:
- A. calibrating alignment of said print heads by;
- a) printing a registration test pattern;
- b) determining lateral alignment between said print heads from said test pattern;
- c) actuating motors connected to said print heads to move said print heads into alignment based upon said lateral alignment determination;
- d) measuring initial skew of said web paper derived from c);
- and
- e) resetting a cumulative motors move log;
- and then
- B. monitoring lateral alignment of said print heads by;
- a) printing a registration test pattern;
- b) determining lateral alignment between said print heads from said test pattern;
- c) actuating motors connected to said print heads to move said print heads into alignment based upon said lateral alignment determination;
- d) updating said cumulative motor move log by adding motor movement in c);
- e) extracting relative skew from said cumulative motor move log;
- and
- f) adding said relative skew to said initial skew to obtain absolute skew.
A method for tracking paper web skew in a printer that includes a series of print heads, comprising:
- providing motors connected to said print heads;
- providing an initial skew in alignment of said print heads;
- providing a cumulative motors move log;
- printing a registration test pattern on said web paper;
- sensing said test pattern with a full width array sensor;
- determining lateral alignment between said print heads from said test pattern;
- actuating said motors to move said print heads into alignment based upon said lateral alignment determination;
- updating said cumulative motor move log by adding motor movement;
- extracting relative skew from said cumulative motor move log;
- and
- adding said relative skew to said initial skew to obtain absolute skew of said web paper.
Dependencies are inferred from the claim text.