Patent US6076915A successfully refreshed from Google Patents.
US6076915A
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Inkjet printhead calibration
Assignee: Hewlett Packard Development Co LP
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Filing: 1998-08-03
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Granted: 2000-06-20
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Expires: 2018-08-03
Abstract
Abstract In various methods, image registration variations among test patterns are used to calibrate misalignment among one or more printheads, paper advance distance, different portions of an inkjet printhead, or bidirectional printhead alignment. A set of test patterns are printed. Each pattern includes a reference portion and a varying portion. The varying portion is changed from pattern to pattern in a manner for testing a parameter being calibrated. An optical sensor scans each test pattern. The parameter setting for the lest pattern having the highest reflectance (i.e., most blank space) is selected as the calibrated parameter value.
Inventors
- 👤 Paul David Gast
- 👤 Mark S Hickman
- 👤 David H. Donovan
- 👤 Xavier Gros
- 👤 Antoni Gil Miquel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:32
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/21; B41J2/2132; B41J2/2135; B41J19/00; B41J19/14; B41J19/142; B41J19/145; B41J29/00; B41J29/38; B41J29/393
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
169 words
A method for calibrating image registration for two inkjet printheads, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: automatically printing a first plurality of test patterns onto a media sheet, each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead, wherein the first portion and second portion are of the same shape, wherein image registration of one of said two inkjet printheads is varied automatically among each one of the plurality of test patterns; sensing reflectance of each one test pattern of the plurality deriving a reflectance value for said each one test pattern of the plurality of test patterns, said derived reflectance value indicative of the sensed reflectance, and selecting the image registration corresponding to a select test pattern of the plurality of test patterns which has a reflectance value indicative of said select test pattern having the most unprinted background area.
Claim 2
Independent Claim
169 words
A method for calibrating image registration for two inkjet printheads, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: automatically printing a first plurality of test patterns onto a media sheet, each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead, wherein the first portion and second portion are of the same shape, wherein image registration of one of said two inkjet printheads is varied automatically among each one of the plurality of test patterns; sensing reflectance of each one test pattern of the plurality deriving a reflectance value for said each one test pattern of the plurality of test patterns, said derived reflectance value indicative of the sensed reflectance, and selecting the image registration corresponding to a select test pattern of the plurality of test patterns which has a reflectance value indicative of said select test pattern having the most unprinted background area.
Claim 3
Dependent Claim
22 words
The method of claim 1, in which the first inkjet printhead prints ink of a differing color than the second inkjet printhead.
Claim 4
Independent Claim
140 words
A method for calibrating image registration for two inkjet printheads, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: automatically printing a first plurality of test patterns onto a media sheet each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead, wherein the first portion and second portion are of the same shape wherein image registration of one printhead of said two printheads is varied automatically for each one test pattern by automatically changing a selection of nozzles of said one printhead used in printing said one test pattern; inspecting the plurality of test patterns; and selecting the image registration corresponding to one of the plurality of test patterns having the most unprinted background area.
Claim 5
Independent Claim
140 words
A method for calibrating image registration for two inkjet printheads, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: automatically printing a first plurality of test patterns onto a media sheet each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead, wherein the first portion and second portion are of the same shape wherein image registration of one printhead of said two printheads is varied automatically for each one test pattern by automatically changing a selection of nozzles of said one printhead used in printing said one test pattern; inspecting the plurality of test patterns; and selecting the image registration corresponding to one of the plurality of test patterns having the most unprinted background area.
Claim 6
Independent Claim
176 words
A method for calibrating image registration for two inkjet printheads of differing color for a prescribed axis, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: automatically printing a first plurality of test patterns onto a media sheet, each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead, wherein the first portion and second portion are of the same shape, wherein image registration of one of said two inkjet printheads is varied automatically among each one of the plurality of test patterns; sensing reflectance of each one test pattern of the plurality deriving a reflectance value for said each one test pattern of the plurality of test patterns, said derived reflectance value indicative of the sensed reflectance; and selecting the image registration corresponding to a select test pattern of the plurality of test patterns which has a reflectance value indicative of said select test pattern having the most unprinted background area.
Claim 7
Independent Claim
176 words
A method for calibrating image registration for two inkjet printheads of differing color for a prescribed axis, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: automatically printing a first plurality of test patterns onto a media sheet, each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead, wherein the first portion and second portion are of the same shape, wherein image registration of one of said two inkjet printheads is varied automatically among each one of the plurality of test patterns; sensing reflectance of each one test pattern of the plurality deriving a reflectance value for said each one test pattern of the plurality of test patterns, said derived reflectance value indicative of the sensed reflectance; and selecting the image registration corresponding to a select test pattern of the plurality of test patterns which has a reflectance value indicative of said select test pattern having the most unprinted background area.
Claim 8
Dependent Claim
22 words
The method of claim 4, in which the first inkjet printhead prints ink of a differing color than the second inkjet printhead.
Claim 9
Dependent Claim
15 words
The method of claim 4, in which each bar includes one line of ink dots.
Claim 10
Independent Claim
147 words
A method for calibrating image registration for two inkjet printheads of differing color for a prescribed axis, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: automatically printing a first plurality of test patterns onto a media sheet each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead wherein the first portion and second portion are of the same shape, wherein image registration of one printhead of said two printheads is varied automatically for each one test pattern by automatically changing a selection of nozzles of said one printhead used in printing said one test pattern; inspecting the plurality of test patterns; and selecting the image registration corresponding to one of the plurality of test patterns having the most unprinted background area.
Claim 11
Independent Claim
147 words
A method for calibrating image registration for two inkjet printheads of differing color for a prescribed axis, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: automatically printing a first plurality of test patterns onto a media sheet each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead wherein the first portion and second portion are of the same shape, wherein image registration of one printhead of said two printheads is varied automatically for each one test pattern by automatically changing a selection of nozzles of said one printhead used in printing said one test pattern; inspecting the plurality of test patterns; and selecting the image registration corresponding to one of the plurality of test patterns having the most unprinted background area.
Claim 12
Independent Claim
163 words
A method for creating a set of test patterns for image registering a plurality of inkjet printheads of differing color, including the steps of: printing a first plurality of test patterns, wherein each one of the first plurality of test patterns includes a plurality of horizontally-spaced vertical bars and is formed by printing ink drops from at least two of the plurality of inkjet printheads, wherein horizontal registration of at least one of said two of the plurality of inkjet printheads is varied among each one of the first plurality of test patterns; and printing a second plurality of test patterns, wherein each one of the second plurality of test patterns includes a plurality of vertically-spaced horizontal bars and is formed by printing ink drops from at least two of the plurality of inkjet printheads, wherein vertical registration of at least one of said two of the plurality of inkjet printheads is varied among each one of the second plurality of test patterns.
Claim 13
Independent Claim
163 words
A method for creating a set of test patterns for image registering a plurality of inkjet printheads of differing color, including the steps of: printing a first plurality of test patterns, wherein each one of the first plurality of test patterns includes a plurality of horizontally-spaced vertical bars and is formed by printing ink drops from at least two of the plurality of inkjet printheads, wherein horizontal registration of at least one of said two of the plurality of inkjet printheads is varied among each one of the first plurality of test patterns; and printing a second plurality of test patterns, wherein each one of the second plurality of test patterns includes a plurality of vertically-spaced horizontal bars and is formed by printing ink drops from at least two of the plurality of inkjet printheads, wherein vertical registration of at least one of said two of the plurality of inkjet printheads is varied among each one of the second plurality of test patterns.
Claim 14
Dependent Claim
192 words
The method of claim 8, in which the first plurality of test patterns are formed by printing ink drops from a reference printhead and a first printhead of the plurality of inkjet printheads, and in which the second plurality of test patterns are formed by printing ink drops from the reference printhead and the first printhead of the plurality of inkjet printheads, and further comprising the steps of: printing a third plurality of test patterns, wherein each one of the third plurality of test patterns includes a plurality of horizontally-spaced vertical bars and is formed by printing ink drops from the reference printhead and a second printhead of the plurality of inkjet printheads, wherein horizontal registration of the second printhead is varied among each one of the first plurality of test patterns; and printing a fourth plurality of test patterns, wherein each one of the fourth plurality of test patterns includes a plurality of vertically-spaced horizontal bars and is formed by printing ink drops from the reference printhead and the second printhead, and wherein vertical registration of the second printhead is varied among each one of the second plurality of test patterns.
Claim 15
Dependent Claim
54 words
The method of claim 8, in which the step of printing the first plurality of test patterns comprises printing the first plurality of test patterns along a first axis, and in which the step of printing the second plurality of test patterns comprises printing the second plurality of test patterns along the first axis.
Claim 16
Dependent Claim
15 words
The method of claim 8, in which each bar includes one line of ink dots.
Claim 17
Independent Claim
482 words
A method for aligning a plurality of inkjet printheads which print ink of differing color along a first axis and a second axis, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: printing a first plurality of test patterns onto a media sheet, wherein each one of the first plurality of test patterns includes a plurality of bars spaced along the first axis on the media sheet, each one of the first plurality of test patterns formed by printing ink drops from a reference printhead of the plurality of inkjet printheads and a first printhead of the plurality of inkjet printheads, wherein image registration for the first axis of said first printhead is varied among each one of the first plurality of test patterns; sensing the reflectance of each one of the first plurality of test patterns; deriving a reflectance value for each one of the first plurality of test patterns corresponding to sensed reflectance; selecting image registration for the first axis for said first printhead to be the image registration in the test pattern of the first plurality of test patterns having the reflectance value which corresponds to a highest reflectance; for each other printhead of the plurality of inkjet printheads other than the reference printhead and the first printhead, repeating the steps of printing a first plurality of test patterns, sensing reflectance of each one of the first plurality of test patterns deriving the reflectance value, and selecting image registration for the first axis to select the image registration for the first axis for said each other printhead; printing a second plurality of test patterns onto a media sheet, wherein each one of the second plurality of test patterns includes a plurality of bars spaced along the second axis on the media sheet, each one of the second plurality of test patterns formed by printing ink drops from the reference printhead and the first printhead, wherein image registration along the second axis of the first printhead is varied among each one of the second plurality of test patterns; sensing the reflectance of each one of the second plurality of test patterns; deriving a reflectance value for each one of the second plurality of test patterns corresponding to sensed reflectance, selecting image registration for the second axis for said first printhead to be the image registration in the test pattern of the second plurality of test patterns having the reflectance value which corresponds to a highest reflectance; and for each other printhead of the plurality of inkjet printheads other than the reference printhead and the first printhead, repeating the steps of printing a second plurality of test patterns, sensing reflectance of each one of the second plurality of test patterns deriving the reflectance value, and selecting image registration for the second axis to select the image registration for the second axis for said each other printhead.
Claim 18
Independent Claim
482 words
A method for aligning a plurality of inkjet printheads which print ink of differing color along a first axis and a second axis, each printhead including a plurality of inkjet nozzles, the method comprising the steps of: printing a first plurality of test patterns onto a media sheet, wherein each one of the first plurality of test patterns includes a plurality of bars spaced along the first axis on the media sheet, each one of the first plurality of test patterns formed by printing ink drops from a reference printhead of the plurality of inkjet printheads and a first printhead of the plurality of inkjet printheads, wherein image registration for the first axis of said first printhead is varied among each one of the first plurality of test patterns; sensing the reflectance of each one of the first plurality of test patterns; deriving a reflectance value for each one of the first plurality of test patterns corresponding to sensed reflectance; selecting image registration for the first axis for said first printhead to be the image registration in the test pattern of the first plurality of test patterns having the reflectance value which corresponds to a highest reflectance; for each other printhead of the plurality of inkjet printheads other than the reference printhead and the first printhead, repeating the steps of printing a first plurality of test patterns, sensing reflectance of each one of the first plurality of test patterns deriving the reflectance value, and selecting image registration for the first axis to select the image registration for the first axis for said each other printhead; printing a second plurality of test patterns onto a media sheet, wherein each one of the second plurality of test patterns includes a plurality of bars spaced along the second axis on the media sheet, each one of the second plurality of test patterns formed by printing ink drops from the reference printhead and the first printhead, wherein image registration along the second axis of the first printhead is varied among each one of the second plurality of test patterns; sensing the reflectance of each one of the second plurality of test patterns; deriving a reflectance value for each one of the second plurality of test patterns corresponding to sensed reflectance, selecting image registration for the second axis for said first printhead to be the image registration in the test pattern of the second plurality of test patterns having the reflectance value which corresponds to a highest reflectance; and for each other printhead of the plurality of inkjet printheads other than the reference printhead and the first printhead, repeating the steps of printing a second plurality of test patterns, sensing reflectance of each one of the second plurality of test patterns deriving the reflectance value, and selecting image registration for the second axis to select the image registration for the second axis for said each other printhead.
Claim 19
Dependent Claim
33 words
The method of claim 12, wherein image registration of a printhead is varied by changing a selection of nozzles of said printhead used for printing a test pattern corresponding to said image registration.
Claim 20
Dependent Claim
15 words
The method of claim 12, in which each bar includes one line of ink dots.
Claim 21
Dependent Claim
314 words
An image registration system for a multi-color inkjet marking apparatus, comprising: a plurality of inkjet printheads, each printhead of the plurality of printheads storing ink of a respective color and having a plurality of nozzles adapted to discharge ink in response to a corresponding electrical signal; a carriage retaining the plurality of inkjet printheads, the carriage moving along a first axis; means for moving a media sheet along a second axis perpendicular to the first axis; control means for providing electrical signals for causing said nozzles to eject ink onto the media sheet and create a first plurality of test patterns and a second plurality of test patterns, wherein each one of the first plurality of test patterns includes a plurality of horizontally-spaced vertical bars and is formed by printing ink drops from at least two of the plurality of inkjet printheads, wherein horizontal registration of at least one of said two of the plurality of inkjet printheads is varied among each one of the first plurality of test patterns, and wherein each one of the second plurality of test patterns includes a plurality of vertically-spaced horizontal bars and is formed by printing ink drops from at least two of the plurality of inkjet printheads, wherein vertical registration of at least one of said two of the plurality of inkjet printheads is varied among each one of the second plurality of test patterns; sensing means for optically sensing reflectance of each one of the first plurality of test patterns and each one of the second plurality of test patterns; and a processor means for sampling the sensing means, for determining which one of the first plurality of test patterns has the highest reflectance and which one of the second plurality of test patterns has the highest reflectance, and for setting horizontal registration and vertical registration for each one of the plurality of inkjet printheads.
Claim 22
Dependent Claim
314 words
An image registration system for a multi-color inkjet marking apparatus, comprising: a plurality of inkjet printheads, each printhead of the plurality of printheads storing ink of a respective color and having a plurality of nozzles adapted to discharge ink in response to a corresponding electrical signal; a carriage retaining the plurality of inkjet printheads, the carriage moving along a first axis; means for moving a media sheet along a second axis perpendicular to the first axis; control means for providing electrical signals for causing said nozzles to eject ink onto the media sheet and create a first plurality of test patterns and a second plurality of test patterns, wherein each one of the first plurality of test patterns includes a plurality of horizontally-spaced vertical bars and is formed by printing ink drops from at least two of the plurality of inkjet printheads, wherein horizontal registration of at least one of said two of the plurality of inkjet printheads is varied among each one of the first plurality of test patterns, and wherein each one of the second plurality of test patterns includes a plurality of vertically-spaced horizontal bars and is formed by printing ink drops from at least two of the plurality of inkjet printheads, wherein vertical registration of at least one of said two of the plurality of inkjet printheads is varied among each one of the second plurality of test patterns; sensing means for optically sensing reflectance of each one of the first plurality of test patterns and each one of the second plurality of test patterns; and a processor means for sampling the sensing means, for determining which one of the first plurality of test patterns has the highest reflectance and which one of the second plurality of test patterns has the highest reflectance, and for setting horizontal registration and vertical registration for each one of the plurality of inkjet printheads.
Claim 23
Dependent Claim
239 words
An image registration system for a multi-color inkjet marking apparatus, comprising: a plurality of inkjet printheads, each printhead of the plurality of printheads having a plurality of nozzles adapted to discharge ink in response to a corresponding electrical signal; a carriage retaining the plurality of inkjet printheads, the carriage moving along a first axis; means for moving a media sheet along a second axis perpendicular to the first axis; control means for providing electrical signals for causing said nozzles to eject ink onto the media sheet and create a first plurality of test patterns, each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead, wherein the first portion and second portion are of the same shape, wherein image registration of one of said two inkjet printheads is varied automatically among each one of the plurality of test patterns; sensing means for optically sensing reflectance of each one of the first plurality of test patterns; and a processor means for sampling the sensing means, for deriving a reflectance value for each test pattern of the first plurality of test patterns, for determining which one of the first plurality of test patterns has the reflectance value which corresponds to the highest reflectance, and for setting image registration of at least one of the first inkjet printhead and the second inkjet printhead.
Claim 24
Dependent Claim
239 words
An image registration system for a multi-color inkjet marking apparatus, comprising: a plurality of inkjet printheads, each printhead of the plurality of printheads having a plurality of nozzles adapted to discharge ink in response to a corresponding electrical signal; a carriage retaining the plurality of inkjet printheads, the carriage moving along a first axis; means for moving a media sheet along a second axis perpendicular to the first axis; control means for providing electrical signals for causing said nozzles to eject ink onto the media sheet and create a first plurality of test patterns, each one test pattern of the plurality of test patterns including a first portion printed with a first inkjet printhead and a second portion printed with a second inkjet printhead, wherein the first portion and second portion are of the same shape, wherein image registration of one of said two inkjet printheads is varied automatically among each one of the plurality of test patterns; sensing means for optically sensing reflectance of each one of the first plurality of test patterns; and a processor means for sampling the sensing means, for deriving a reflectance value for each test pattern of the first plurality of test patterns, for determining which one of the first plurality of test patterns has the reflectance value which corresponds to the highest reflectance, and for setting image registration of at least one of the first inkjet printhead and the second inkjet printhead.
Claim 25
Independent Claim
216 words
A method for calibrating media advance distance in an inkjet printer having a printhead with a plurality of nozzles, comprising the steps of: printing a first portion of a first test pattern onto a media sheet using a first subset of the plurality of nozzles; advancing the media sheet by a media advance distance; overprinting a second portion of the first test pattern onto the media sheet in the area of the first portion using a second subset of the plurality of nozzles, wherein the second portion has a common pattern as the first portion; iteratively repeating the steps of printing a first portion, advancing the media sheet and printing a second portion for additional test patterns, wherein the media advance distance is varied in each iteration, and wherein a plurality of test patterns is achieved corresponding to a plurality of the iterations; sensing reflectance of each one test pattern of the plurality of test patterns; deriving a reflectance value for said each one test pattern of the plurality of test patterns, said derived reflectance value indicative of the sensed reflectance; and selecting the media advance distance corresponding to a select test pattern of the plurality of test patterns which has a reflectance value indicative of said select test pattern having the most unprinted background area.
Claim 26
Independent Claim
216 words
A method for calibrating media advance distance in an inkjet printer having a printhead with a plurality of nozzles, comprising the steps of: printing a first portion of a first test pattern onto a media sheet using a first subset of the plurality of nozzles; advancing the media sheet by a media advance distance; overprinting a second portion of the first test pattern onto the media sheet in the area of the first portion using a second subset of the plurality of nozzles, wherein the second portion has a common pattern as the first portion; iteratively repeating the steps of printing a first portion, advancing the media sheet and printing a second portion for additional test patterns, wherein the media advance distance is varied in each iteration, and wherein a plurality of test patterns is achieved corresponding to a plurality of the iterations; sensing reflectance of each one test pattern of the plurality of test patterns; deriving a reflectance value for said each one test pattern of the plurality of test patterns, said derived reflectance value indicative of the sensed reflectance; and selecting the media advance distance corresponding to a select test pattern of the plurality of test patterns which has a reflectance value indicative of said select test pattern having the most unprinted background area.
Claim 27
Dependent Claim
25 words
The method of claim 17, in which the selecting step comprises selecting the media advance distance corresponding to the test pattern exhibiting the most reflectance.
Claim 28
Independent Claim
190 words
A method for calibrating inter-column alignment for an inkjet print head having a plurality of nozzles, the method comprising the steps of: automatically printing a first portion of each one of a plurality of test patterns onto a media sheet using a first subset of the plurality of nozzles, wherein the first portion for said each one of the plurality of test patterns are spaced by a common interval; overprinting a second portion of each one of the plurality of test patterns onto the media sheet in the area of the first portion using a second subset of the plurality of nozzles, wherein the second portion has a common pattern as the first portion, and wherein the second portion for said each one of the plurality of test patterns are spaced by a variable interval, and wherein the first subset of nozzles and the second subset comprise nozzles are from mutually exclusive columns of the plurality of columns; inspecting the plurality of test patterns; and selecting the interval corresponding to the test pattern in which the first portion and second portion are most closely aligned as a calibrated inter-column offset.
Claim 29
Independent Claim
190 words
A method for calibrating inter-column alignment for an inkjet print head having a plurality of nozzles, the method comprising the steps of: automatically printing a first portion of each one of a plurality of test patterns onto a media sheet using a first subset of the plurality of nozzles, wherein the first portion for said each one of the plurality of test patterns are spaced by a common interval; overprinting a second portion of each one of the plurality of test patterns onto the media sheet in the area of the first portion using a second subset of the plurality of nozzles, wherein the second portion has a common pattern as the first portion, and wherein the second portion for said each one of the plurality of test patterns are spaced by a variable interval, and wherein the first subset of nozzles and the second subset comprise nozzles are from mutually exclusive columns of the plurality of columns; inspecting the plurality of test patterns; and selecting the interval corresponding to the test pattern in which the first portion and second portion are most closely aligned as a calibrated inter-column offset.
Claim 30
Dependent Claim
26 words
The method of claim 19, wherein for each one of the plurality of test patterns, a selection of nozzles forming the second subset is automatically varied.
Claim 31
Independent Claim
159 words
A method for calibrating array length variation within an inkjet printhead having a plurality of nozzles, the method comprising the steps of: automatically printing a first portion of each one of a plurality of test patterns onto a media sheet using a first subset of the plurality of nozzles; overprinting a second portion of each one of the plurality of test patterns onto the media sheet in the area of the first portion using a second subset of the plurality of nozzles, wherein the second portion has a common pattern as the first portions wherein the first subset of nozzles and the second subset comprise nozzles are from mutually exclusive portions of the printhead; during the step of overprinting, advancing the media sheet; inspecting the plurality of test patterns; and selecting a media sheet advance distance corresponding to the test pattern in which the first portion and second portion are most closely aligned as a calibrated array length offset.
Claim 32
Independent Claim
159 words
A method for calibrating array length variation within an inkjet printhead having a plurality of nozzles, the method comprising the steps of: automatically printing a first portion of each one of a plurality of test patterns onto a media sheet using a first subset of the plurality of nozzles; overprinting a second portion of each one of the plurality of test patterns onto the media sheet in the area of the first portion using a second subset of the plurality of nozzles, wherein the second portion has a common pattern as the first portions wherein the first subset of nozzles and the second subset comprise nozzles are from mutually exclusive portions of the printhead; during the step of overprinting, advancing the media sheet; inspecting the plurality of test patterns; and selecting a media sheet advance distance corresponding to the test pattern in which the first portion and second portion are most closely aligned as a calibrated array length offset.
Claim 33
Dependent Claim
26 words
The method of claim 21, wherein for each one of the plurality of test patterns, a selection of nozzles forming the second subset is automatically varied.
Claim 34
Independent Claim
199 words
A method for calibrating image registration for bidirectional printing with in inkjet printhead having a plurality of nozzles, the method comprising the steps of: printing a first portion of each one of a plurality of test patterns onto a media sheet while the printhead is scanned across the media sheet in a first direction, wherein the first portion for said each one are spaced by a common interval; overprinting a second portion of each one of the plurality of test patterns onto the media sheet in the area of the first portion while the printhead is scanned across the media sheet in a second direction opposite the first direction, wherein the second portion has a common pattern as the first portion, and wherein the second portion for said each one are spaced by a variable interval; sensing reflectance of each one test pattern of the plurality of test patterns; deriving a reflectance value for said each one test pattern of the plurality of test patterns, said derived reflectance value indicative of the sensed reflectance; and selecting the interval corresponding to the select test pattern for which the reflectance value of the select test pattern indicates a highest reflectance value.
Claim 35
Independent Claim
199 words
A method for calibrating image registration for bidirectional printing with in inkjet printhead having a plurality of nozzles, the method comprising the steps of: printing a first portion of each one of a plurality of test patterns onto a media sheet while the printhead is scanned across the media sheet in a first direction, wherein the first portion for said each one are spaced by a common interval; overprinting a second portion of each one of the plurality of test patterns onto the media sheet in the area of the first portion while the printhead is scanned across the media sheet in a second direction opposite the first direction, wherein the second portion has a common pattern as the first portion, and wherein the second portion for said each one are spaced by a variable interval; sensing reflectance of each one test pattern of the plurality of test patterns; deriving a reflectance value for said each one test pattern of the plurality of test patterns, said derived reflectance value indicative of the sensed reflectance; and selecting the interval corresponding to the select test pattern for which the reflectance value of the select test pattern indicates a highest reflectance value.
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USPTO Annuity & Maintenance Windows
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|---|---|---|---|---|---|
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| 7.5 Years (Year 8) | 2007-06-20 | 2007-12-20 | 2008-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-06-20 | 2011-12-20 | 2012-06-20 | $7700.00 | Window Closed / Lapsed |