Real-time linefeed measurement of inkjet printer
AssigneeCanon Kabushiki Kaisha
InventorJumpei ASHIDA
Life of this patent
Estimating the term…
Abstract
A method of halftoning of an image comprising a pseudo-noise pattern of dots, whereby vectors between each dot and the nearest neighbouring dot are orientated in a direction perpendicular to a line feed direction, and a density of the pattern of dots in a line feed direction is half of a density of the pattern of dots in a direction perpendicular to the line feed direction
Claims10
A method of determining line feed error in an image forming apparatus for printing a reference image on a print medium, said image forming apparatus comprising a print head having a head sensor configured to sense information from images printed on the print medium, said method comprising the steps of:
- printing a first swath of a halftone image of the reference image on the print medium, said first swath having a dot pattern oriented in a direction perpendicular to a direction of linefeed of the image forming apparatus;
- repositioning the print head relative to the print medium by at least one line feed distance;
- determining a line feed error based upon information sensed by the head sensor from the printed first swath;
- and
- printing, using the determined line feed error, a second swath of the halftone image of the reference image on the print medium, wherein said second swath:
- (i) at least partially overlaps the first swath;
- and
- (ii) has a dot pattern configured to at least partly neutralise, in an overlap area of the first swath and the second swath, the orientation of the first swath dot pattern in the halftone image.
A method of forming a halftone image on a print medium using a print head of an image forming apparatus, said method comprising the steps of:
- printing a first pattern of marks on the print medium in a first pass of the print head over the print medium, said first pattern of marks being oriented in a direction perpendicular to the direction of linefeed of the image forming apparatus, said first pattern of marks forming a transitory test chart prior to printing of a second pattern of marks being at least partially overlayed on the printed first pattern of marks and at least partly neutralising the orientation of the first pattern of marks;
- and
- printing the second pattern of marks on the print medium in a second pass of the print head over the print medium, said second pattern of marks being configured to be of opposite phase to and oriented in the same direction as the first pattern of marks, said second pattern of marks being at least partially overlayed on the printed first pattern of marks and at least partly neutralising the orientation of the first pattern of marks in the overlap area of the halftone image.
A method of constructing a test chart wherein each printing pass comprises a pseudo-noise pattern of dots;
- wherein in a first printing pass:
- vectors between each dot and the nearest neighbouring dot are orientated in a direction perpendicular to a line feed direction;
- and
- a density of the pattern of dots in a line feed direction is less than a density of the pattern of dots in a direction perpendicular to the line feed direction.
An image forming apparatus for printing a reference image on a print medium, said image forming apparatus comprising:
- a processor;
- a memory storing a computer executable program for directing the processor to execute a method for determining line feed error in the printed image;
- and
- a print head having a head sensor configured to sense information from images to printed on the print medium;
- the program comprising:
- computer executable code for printing a first swath of a halftone image of the reference image on the print medium, said first swath having a dot pattern oriented in a direction perpendicular to a direction of linefeed of the image forming apparatus;
- computer executable code for repositioning the print head relative to the print medium by at least one line feed distance;
- computer executable code for determining a line feed error based upon information sensed by the head sensor from the printed first swath;
- and
- computer executable code for printing, using the determined line feed error, a second swath of the halftone image of the reference image on the print medium, wherein said second swath:
- (i) at least partially overlaps the first swath;
- and
- (ii) has a dot pattern configured to at least partly neutralise, in an overlap area of the first swath and the second swath, the orientation of the first swath dot pattern in the halftone image.
A tangible computer readable non-transitory storage medium storing a computer executable program for directing a processor, in an image forming apparatus comprising a print head having a head sensor configured to sense information from images printed on a print medium, to execute a method for determining line feed error in an image printed by the image forming apparatus;
- the program comprising:
- computer executable code for printing a first swath of a halftone image of the reference image on the print medium, said first swath having a dot pattern oriented in a direction perpendicular to a direction of linefeed of the image forming apparatus;
- computer executable code for repositioning the print head relative to the print medium by at least one line feed distance;
- computer executable code for determining a line feed error based upon information sensed by the head sensor from the printed first swath;
- and
- computer executable code for printing, using the determined line feed error, a second swath of the halftone image of the reference image on the print medium, wherein said second swath:
- (i) at least partially overlaps the first swath;
- and
- (ii) has a dot pattern configured to at least partly neutralise, in an overlap area of the first swath and the second swath, the orientation of the first swath dot pattern in the halftone image.
Dependencies are inferred from the claim text.