Printing with a multi-segment printhead

• US 6,394,573 B1
• Filed: 06/28/2000
• Issued: 05/28/2002
• Est. Priority Date: 06/28/2000
• Status: Expired due to Term

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Lapstun, Paul, Walmsley, Simon Robert
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Stewart, Jr., Charles W.
• Application Number:
  US09/607,196
• Time in Patent Office: 699 Days
• Field of Search: 347/19,41,42,43,14,59 358/75,283,57 382/274
• US Class Current: 347/19
• CPC Class Codes: G06K 15/10 by matrix printers G06K15/028 takes precedence
• CPC Class Codes: G06K 2215/111 with overlapping swaths
• CPC Class Codes: H04N 1/1903 Arrangements for enabling electronic abutment of lines or areas independently scanned by different elements of an array or by different arrays
• CPC Class Codes: H04N 1/1934 Combination of arrays

Abstract

A method of preparing print data for a multi-segment printhead in which is established a set of dither matrices for a multi-segment printhead comprised of a plurality printhead chips with end portions overlapped, the set consisting of a lead-in dither matrix associated with a lead in overlap portion, a lead-out dither matrix associated with a lead out overlap portion and a common dither matrix associated with a central portion of the printhead chip. Received print data composited with dither values from the set. The lead-in dither values establish fade-in of one segment and the lead-out dither values establish fade-out of the preceding segment. In each two overlapping segments overlap is characterized in terms of a misalignment and the misalignment is used to generate an offset leading into the common dither matrix.

Claims

1. A method of preparing print data for a multi-segment printhead including:

establishing a set of dither matrices for a multi-segment printhead comprised of a plurality of printhead chips with end portions overlapped, the set consisting of a lead-in dither matrix associated with a lead in overlap portion,

a lead-out dither matrix associated with a lead out overlap portion; and

a common dither matrix associated with a central portion of the printhead chip;

receiving print data; and

accessing the dither matrix set and applying dither to received data as the data is composited to maintain a substantially constant dot gain in the resultant image across overlap portions.

2. A method of preparing print data as claimed in claim 1 wherein the lead-in dither values establish fade-in of one segment and the lead-out dither values establish fade-out of the preceding segment, and the combination of the two provides near constant dot-gain over the overlap portion.

3. A method of preparing print data as claimed in claim 1 wherein in each two overlapping segments overlap is characterized in terms of a misalignment and the misalignment is used to generate an offset leading into the common dither matrix.

4. A method of preparing print data as claimed in claim 3 wherein the misalignment information is obtained from a characterization vector stored in respect of each printhead segment.

5. A method of preparing print data as claimed in claim 4 wherein the characterization vectors from the multiple segments of the printhead are combined to construct a nozzle defect list for the entire printhead.

6. A printer having a multi-segment printhead including:

an interface at which to receive print data;

a halftoner/compositor to composite the received print data; and

a printhead interface putting composited print data from the halftoner/compositor to the multi-segment printhead;

the halftoner/compositor including a dither matrix access unit presenting a dither matrix used in compositing print data, to maintain a substantially constant dot gain in the resultant image;

the dither matrix access unit addressing a dither matrix that is a composite of a set of dither matrices for the multi-segment printhead with segments overlapped at respective ends;

the set consisting of

a lead-in dither matrix;

a lead-out dither matrix; and

a central region dither matrix.

7. A printer as claimed in claim 6 wherein the lead-in dither values establish fade-in of one segment and the lead-out dither values establish fade-out of the preceding segment, and the combination of the two provides near constant dot-gain over the overlap portion.

8. A printer as claimed in claim 6 wherein for each set of two overlapping segments there is overlap characterized in terms of a misalignment and misalignment is used to generate an offset leading into the central region dither matrix.

9. A printer as claimed in claim 7 wherein the misalignment information is obtained from a characterization vector stored on each printhead segment and they are combined to construct a nozzle defect list for the entire printhead.