EP0775587A1
Expired / Lapsed
EP
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Inkjet printhead alignment via measurement and entry
Assignee: HP Inc
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Filing: 1996-04-11
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Granted: —
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Expires: 2016-04-11
Abstract
Abstract Optical measurement is made for each nozzle (56) position of a printhead (38-44) relative to each printhead of an inkjet printing device (10). Alternatively, the measurement is made for each nozzle relative to a reference point. The reference point, for example, is a datum projection or indentation (i) on the printhead (e.g., 72-78), (ii) integral to the pen body (e.g., 82-88), or (iii) on the pen carriage. The measurement data subsequently is stored for later access. Alternative storage schemes include local storage in electronic memory associated with the pen and physical storage via bar code, magnetic stripes or physical markings. The stored alignment data thereafter is retrieved and input to printhead nozzle management software to adjust the timing for firing respective nozzles. The timing is adjusted to compensate for misalignment and achieve accurate dot placement on a media sheet.
Inventors
- 👤 David E. Hackleman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:46
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/21; B41J2/2132; B41J2/2135; B41J2/17; B41J2/175; B41J2/17503; B41J2/17526; B41J2/1753; B41J2/17543; B41J2/17546; B41J25/00; B41J25/34; B41J2202/00; B41J2202/01; B41J2202/17
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
98 words
An inkjet pen apparatus (18/20/22/24) for use with an inkjet printing device (10), comprising: a printhead (38/40/42/44) comprising a plurality of nozzles (56), each one of said plurality of nozzles defining a nozzle chamber for receiving ink; a pen body (18/20/22/24) to which the printhead is attached, the pen comprising a reservoir for holding ink, the reservoir coupled to the nozzle chambers; a reference point (72/74/76/78/82/84/86/88) against which locations of the printhead nozzles are measured; and means (52/110/120-122) for storing a misalignment indicator corresponding to a misalignment of the printhead, the misalignment indicator derived from printhead nozzle locations.
Claim 2
Dependent Claim
18 words
The pen apparatus of claim 1, in which the storing means comprises an optically detectable bar code (110).
Claim 3
Dependent Claim
20 words
The pen apparatus of claim 1, in which the printhead further comprises electronic memory which serves as the storing means.
Claim 4
Dependent Claim
47 words
The pen apparatus of claim 1, in which the storing means comprises a first marking (120) on the pen body and a second marking (122) on the pen body, and wherein the relative offset of the second marking to the first marking is indicative of printhead misalignment.
Claim 5
Dependent Claim
37 words
The pen apparatus of claim 4, in which the second marking (122) is adjustable to define a rotational offset relative to the first marking which is indicative of rotational skew of a nozzle row on the printhead.
Claim 6
Independent Claim
141 words
A method for adjusting the timing of printhead nozzles (56) to compensate for printhead misalignment in an inkjet printing apparatus (10) comprising a plurality of inkjet pens (18-24), each one of the plurality of inkjet pens comprising a printhead (38/40/42/44), a pen body to which the printhead is attached, and a reference point (72/82, 74/84, 76/86, 78/88), each printhead having a plurality of nozzles through which ink is ejected for printing to a media sheet, the method comprising the steps of: for each printhead optically measuring printhead alignment relative to the reference point of the pen comprising such printhead; embedding printhead alignment data into each pen, said data corresponding to the printhead of the pen at which the data is embedded; retrieving the embedded printhead misalignment data; and adjusting nozzle timing to compensate for printhead misalignment based upon the retrieved data.
Claim 7
Dependent Claim
38 words
The method of claim 6 in which each pen further comprises electronic memory, and in which the step of embedding comprising storing the printhead alignment data in the electronic memory of the pen to which the data pertains.
Claim 8
Dependent Claim
23 words
The method of claim 6 in which the step of embedding comprises applying an optically-detectable bar code (110) of the printhead alignment data.
Claim 9
Dependent Claim
56 words
The method of claim 6 in which each pen further comprises a first marker (120) and a second marker (122), and in which the step of embedding comprises adjusting the second marker position relative to the first marker position, and in which the relative position of the first and second marker embodies the printhead misalignment data.
Claim 10
Dependent Claim
68 words
The method of claim 9 in which the relative position indicates any one or more of a first planar offset, a second planar offset and a rotational offset, each one of the first planar offset, second planar offset and rotational offset occurring in a plane of the printhead, and in which the first planar offset is for a direction orthogonal for a direction of the second planar offset.
References Cited (Backward Citations)
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