Print engine controller for a multi-segment printhead

• US 6,747,760 B2
• Filed: 06/19/2002
• Issued: 06/08/2004
• Est. Priority Date: 05/23/2000
• Status: Expired due to Fees

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Lapstun, Paul, Walmsley, Simon Robert
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US10/173,739
• Publication Number:
  US 20030072036A1
• Time in Patent Office: 720 Days
• Field of Search: 358/3.13, 358/3.14, 358/1.8, 358/1.9, 358/3.26, 358/3.06, 358/535, 358/534, 358/502, 358/504, 358/406, 358/466, 347/19, 347/42, 347/3, 347/5, 347/14, 347/15, 382/270
• US Class Current: 358/3.13
• CPC Class Codes: B41J 2/2132 Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding methods for local corrections by dot omission, image edge enhancement, or multi-pass mask selection G06K15/102; colour conversion H04N1/40
• CPC Class Codes: H04N 1/3871 the composed originals being of different kinds, e.g. low- and high-resolution originals
• CPC Class Codes: H04N 1/405 Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
• CPC Class Codes: H04N 1/4051 producing a dispersed dots halftone pattern, the dots having substantially the same size different sizes H04N1/4057

Abstract

An inkjet printer comprises a printhead that includes a number of printhead segments that span a print area so that portions of consecutive printhead segments overlap in common print areas. Each printhead segment defines a lead-in area in one common print area and a lead-out area in a consecutive common print area. An interface is configured to receive image data. A memory device stores data relating to characteristics of the printhead. A dithering unit communicates with the interface and the memory device. The dithering unit is configured to generate a lead-in dither matrix associated with the lead-in area and a lead-out dither matrix associated with the lead-out area, to generate lead-in/lead-out dither matrices for each common print area, to generate a variable probability value that is dependent on a scalar value that corresponds to a position along a line spanning each common print area and to interpolate the lead-in/lead-out dither matrices with the variable probability value. A compositor communicates with the dithering unit to composite the data into print data. A printhead interface communicates with the compositor to receive the print data and to provide the printhead with the print data.

Claims

1. A method of controlling a print engine for a multi-segment printhead having a plurality of printhead segments that are positioned in a printhead to span a print area so that portions of consecutive printhead segments overlap in common print areas, with each printhead segment defining a lead-in area in one common print area and a lead-out area in a consecutive common print area, the method comprising the steps of:

generating a set of dither matrices for each printhead segment, each set having at least a lead-in dither matrix associated with the lead-in area and a lead-out dither matrix associated with the lead-out area;

generating lead-in/lead-out dither matrices for each common print area based on characteristics of the printhead segments of each common print area;

generating a variable probability value that is dependent on a scalar value that corresponds to a position along a line spanning each common print area;

interpolating the lead-in/lead-out dither matrices with the variable probability value to generate interpolated lead-in/lead-out dither matrices;

loading a compositor with the data representing the matrices;

compositing print data based on the dither matrices; and

providing the printhead with the print data.

2. A method as claimed in claim 1, which includes the steps of:

querying the printhead segments to generate data in the form of a characterization vector that is unique to the printhead;

loading a memory device with the characterization vector; and

reading the characterization vector to carry out the step of generating the lead-in/lead-out dither matrices.

3. A method as claimed in claim 1, which includes the step of generating a dither matrix for a non-overlapping portion of each printhead segment.

4. A print engine controller for a multi-segment printhead having a plurality of printhead segments that are positioned in a printhead to span a print area so that portions of consecutive printhead segments overlap in common print areas, with each printhead segment defining a lead-in area in one common print area and a lead-out area in a consecutive common print area, the print engine controller comprising

an interface which is configured to receive image data;

a memory device that is capable of storing data relating to characteristics of the multi-segment printhead;

a dithering unit that communicates with the interface to receive the image data from the interface and the memory device to receive data relating to the characteristics of the multi-segment printhead, the dithering unit being configured to generate a set of dither matrices for each printhead segment so that each set has at least a lead-in dither matrix associated with the lead-in area and a lead-out dither matrix associated with the lead-out area, to generate lead-in/lead-out dither matrices for each common print area based on characteristics of the printhead segments of each common print area, to generate a variable probability value that is dependent on a scalar value that corresponds to a position along a line spanning each common print area and to interpolate the lead-in/lead-out dither matrices with the variable probability value to generate interpolated lead-in/lead-out dither matrices;

a compositor that communicates with the dithering unit to receive data representing the interpolated lead-in/lead-out dither matrices and to composite the data into print data; and

a printhead interface that communicates with the compositor to receive the print data, the printhead interface being in communication with the multi-segment printhead to provide the multi-segment printhead with the print data.

5. A print engine controller as claimed in claim 4, in which the dithering unit is configured to generate a dither matrix for each non-overlapping area of the printhead segments.

6. An inkjet printer that comprises

a printhead that includes a number of printhead segments that span a print area, the printhead segments being positioned so that portions of consecutive printhead segments overlap in common print areas, with each printhead segment defining a lead-in area in one common print area and a lead-out area in a consecutive common print area;

an interface which is configured to receive image data;

a memory device that is capable of storing data relating to characteristics of the printhead;

a dithering unit that communicates with the interface to receive the image data from the interface and the memory device to receive data relating to the characteristics of the printhead, the dithering unit being configured to generate a set of dither matrices for each printhead segment so that each set has at least a lead-in dither matrix associated with the lead-in area and a lead-out dither matrix associated with the lead-out area, to generate lead-in/lead-out dither matrices for each common print area based on characteristics of the printhead segments of each common print area, to generate a variable probability value that is dependent on a scalar value that corresponds to a position along a line spanning each common print area and to interpolate the lead-in/lead-out dither matrices with the variable probability value to generate interpolated lead-in/lead-out dither matrices;

a compositor that communicates with the dithering unit to receive data representing the interpolated lead-in/lead-out dither matrices and to composite the data into print data; and

a printhead interface that communicates with the compositor to receive the print data, the printhead interface being in communication with the printhead to provide the printhead with the print data.

7. A printer as claimed in claim 6 wherein each common print area defined by consecutive printhead segments has a width of at least 1 mm.