Eastman-kodak Company

Mark C Rzadca

Samuel Chen

Thomas D Pawlik

Lynn Schilling-Benz

Michael Joseph Piatt

John T Keech

Eric Karl Zeise

James Michael Enge

Thomas F Powers

James Stephen Honan

David C Press

George T McCollough

A printing system includes a linehead that jets ink onto a moving print media to print a test block and an integrated imaging system positioned downstream of the linehead with respect to a media transport direction. The integrated imaging system includes an opening in a housing for receiving light reflected from a moving print media. A folded optical assembly in the housing receives the reflected light and transmits the light a distance. One or more image sensors, having known color filter arrays, within the housing each receive the light and capture one or more images of the printed test block. An image processing device is connected to the integrated imaging system for receiving pixel data from the one or more image sensors and configured to determine a color of the ink and a density of the printed test block using the pixel data.

Printhead color density correction in printing systems

A method for color density correction in a printing system that includes a linehead, with one or more printheads, that jets ink onto a moving print media and an integrated imaging system that captures images of content printed on the moving print media is provided. One or more pixel data values and a measured density value trace for a printed test block are produced by scanning the test block and averaging pixel data in a print media transport direction. A color and a density of the ink in the printed test block are determined using the pixel data values. The measured density value trace is compared with a respective reference density value. It is determined whether there is a difference between the measured density value trace and a reference density value is determined. If there is a difference, ink laydown for the printhead is adjusted based on the difference.

A system for testing one or more nozzles in a nozzle plate includes a fixture for holding the nozzle plate, a gas input device for jetting gas through the nozzle, and a first stationary schlieren optical system for producing a light-intensity representation of a gas stream jetted from the nozzle. An image capture device can capture one or more images of the light-intensity representation or the light-intensity representation can be projected onto a screen.

Testing of nozzles used in printing systems

A printing system includes at least one linehead that jets ink onto a print media and an integrated imaging system that captures images of the content printed on the print media. Each linehead includes one or more printheads. A flat field correction method for the printing system includes one or more printheads printing a test block having a known print density on the print media and producing a density variation trace for each of the one or more printheads by capturing an image of each printed test block and averaging pixel data in a transport direction. A negative print mask is then produced for each printhead in the one or more printheads by inverting each density variation trace. Each negative print mask is added to, or subtracted from, respective print data values transmitted to each respective printhead in the one or more printheads.

Flat field and density correction in printing systems

A method for testing a nozzle in a nozzle plate includes jetting gas through the nozzle and forming one or more light-intensity representations of a gas stream jetted from the nozzle using at least one stationary schlieren optical system. One or more images can be captured of the one or more light-intensity representations of the gas stream jetted from the nozzle. Alternatively, respective light-intensity representations of the gas stream jetted from the nozzle can be projected onto a screen.

A method for monitoring stitching between two adjacent printheads includes capturing one or more images of content printed on a moving print media in at least a stitch boundary or overlap region to obtain pixel data. The pixel data is then averaged in a media transport direction to produce blur in an image or images. Derivative data of the averaged pixel data is determined and one or more peaks is detected in the derivative data. A type of stitching artifact is determined based on the detected peak in the derivative data.

Incorrect stitching detection in a printing system

A density variation correction method for a printing system includes printheads in at least one linehead printing a test block pattern on a print media. A density variation trace is produced for each printed test block in the test block patterns by capturing an image of each test block and averaging pixel data in a transport direction. The density variation traces associated with a known print density represented in the test block pattern are compared with a respective reference density value. A determination is made as to whether there is a difference between each density variation trace and the respective reference density value. If there is a difference, the density variation trace is adjusted to match the reference density value. The method can be repeated for all of the known print densities represented in the test block pattern and for all of the lineheads in the printing system.

A printing system includes a print media having two sets of test patterns formed or printed in at least two margins adjacent a content area on the print media. The two sets of test patterns are separated by a pattern distance and at least two test patterns in each set of test patterns have a different number of marks. Two integrated imaging systems are disposed opposite the print media and are mechanically tied together and separated by a fixed distance. The integrated imaging systems substantially simultaneously capture images of the two sets of test patterns. An image processing device can process the images to determine if one or more size variations have occurred in the print media in the in-track direction.

Detecting stretch or shrink in print media

A print media in a printing system includes multiple test patterns with each test pattern having one or more marks. Each test pattern can have a different number of marks. A method for detecting size variations in the print media while the print media is moving through the printing system includes scanning the test patterns as the print media is moving in a transport direction to produce test pattern signals, with each signal representing a respective test pattern, and analyzing the measured test pattern signals to determine whether a size variation has occurred in the print media. One or more compensation values can be determined based on the size variation. If a size variation is detected, the operation or setting of one or more components in the printing system can be adjusted based on the one or more compensation values.

A printing system includes a print media and one or more non-objectionable test patterns formed or printed on the print media. An integrated imaging system captures images of the one or more non-objectionable test patterns. The integrated imaging system includes a housing, an opening in the housing for receiving light reflected from a moving print media, a folded optical assembly in the housing that receives the reflected light and transmits the light a predetermined distance, and an image sensor within the housing that receives the light and captures one or more images of the one or more non-objectionable test patterns. A processing device can process the one or more images to determine if one or more size variations have occurred in the print media.

A method for testing a nozzle in a nozzle plate includes setting an angle of the nozzle plate with respect to an optical axis of a schlieren optical system to a first angle, jetting gas through the nozzle, forming a first light-intensity representation of the gas stream jetting from the nozzle using the schlieren optical system, and capturing a first image of the first light-intensity representation. The angle of the nozzle plate with respect to the optical axis of the schlieren optical system is then adjusted to a different second angle. A second light-intensity representation of the gas stream jetting from the nozzle is formed using the schlieren optical system and a second image of the second light-intensity representation is then captured. The first and second images can be analyzed to determine whether the nozzle is functioning properly.

A linehead that is producing an artifact in the content printed on a print media is identified by capturing an image of the content as the print media is moving to obtain pixel data and averaging the pixel data to produce blur in a direction the print media is moving. A determination is made as to whether the averaged pixel data is associated with content printed by a first linehead in a printing module. If the averaged pixel data is not associated with the first linehead, the averaged pixel data from an image captured by a preceding linehead is subtracted from the averaged pixel data in the image to produce averaged pixel data that is associated with a single linehead. Derivative data of the averaged pixel data is then determined. A determination is made as to whether one or more peaks are present in the derivative data.

Identifying a linehead producing an artifact in content printed on a moving print media

A method for determining a variance of a sensor in inkjet printers comprising maintaining a printer carriage at a stationary position; illuminating a media patch of known characteristics with a light source that varies an intensity of the light between at least a first and second intensity, in which the second intensity is different from the first intensity; obtaining an amount of light transmitted through the media patch by measuring a signal from a photo-detector during the illumination; and comparing the amount of received light to stored target values to determine a variation of the sensor response for forming a correction factor; and using the correction factor to calibrate at least a first signal of the inkjet printer.

Method for adjusting a sensor response

A method for determining a variance of a sensor in inkjet printers includes maintaining a printer carriage at a stationary position; illuminating a media patch of known characteristics with a light source that varies an intensity of the light between at least a first and second intensity, in which the second intensity is different from the first intensity; obtaining at least specular reflectance data from light reflected off the print media by measuring a signal from a photo-detector during the illumination; and comparing the specular data to stored values to determine a variation of the sensor response for forming a correction factor; and using the correction factor to calibrate at least a first signal of the inkjet printer.

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Fairport, NY, United States of America

Mark C Rzadca