EP0558284A2
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EP
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Method and apparatus for correcting printing distortions in an ink jet printer
Assignee: Videojet Technologies Inc
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Filing: 1993-02-24
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Granted: —
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Expires: 2013-02-24
Abstract
Abstract Printing distortions caused by ink stream/charge tunnel (14, 16) misalignment, charge tunnel mis-dimensioning or a variation in drop spacing or changes in ink resistivity are corrected by measuring the actual induction coefficients for a particular printer. For this purpose, charge sensors (30, 31) located along the ink stream or adjacent the ink catcher (28) detect induced charges from which the induction coefficients are calculated by a programmable controller (18). These coefficients are used to adjust the charge tunnel voltages to reduce or eliminate printing distortion.
Inventors
- 👤 Bruce Ortquist
- 👤 Timothy Braun
- 👤 Robert I Keur
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 14:38
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/07; B41J2/12
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
83 words
A method for field adjusting the calibrated charge tunnel voltages, V n of an ink jet printer to reduce printing distortion characterised by the method comprising the steps of: a) measuring the actual values of the induction coefficients, I m for said printer; b) altering the voltages V n by a factor related to the difference between β m , the calibrated induction coefficients, and I m to obtain adjusted voltages Φ n ; c) employing the adjusted voltages Φ n for printing.
Claim 2
Dependent Claim
37 words
A method according to Claim 1 and further characterised by the voltages V n being altered according to the formula; Φ n = V n + (I₁ - β ₁) V n-1 for a first order correction.
Claim 3
Dependent Claim
48 words
A method according to Claim 1 and further characterised by the voltages V n being altered according to the formula: Φ n = V n + (I₁ - β ₁) V n-1 + [(I₂ - β₂ ) -β₁ (I₁ -β ₁)] V n-2 for a second order correction.
Claim 4
Independent Claim
79 words
A method according to any preceding Claim and further characterised by the voltages V n being stored in a memory element associated with said printer in the form of a default voltage table and the method also including the steps of: reading the voltages V n from said table to permit alteration; storing the adjusted voltages Φ n in said memory element in a corrected voltage table; printing from the corrected voltage table rather than the default voltage table.
Claim 5
Independent Claim
94 words
A method according to any preceding Claim and further characterised by the step of measuring the induction coefficients I n including the substeps of: i) applying voltages V₁ and V₂, V₂ initially being equal to V₁, to a pair of test drops d₁ and d₂ respectively to induce charges q₁ and q₂ on said drops; ii) measuring the induced charges q₁ and q₂; iii) incrementing V₂ and repeating steps i) and ii) until q₁=q₂; iv) calculating the actual induction coefficients, I m , using the values of V₁ and V₂ when q₁ = q₂.
Claim 6
Dependent Claim
40 words
A method according to Claim 5 and further characterised by the step of calculating I n employing the formula: I n =α 1-n V₂ V₁ - 1 n , α = e -1/2 where n is the order of correction.
Claim 7
Independent Claim
142 words
A method according to any one of Claims 1 to 4 and further characterised by the step of measuring the induction coefficients In including the substeps of: i) applying voltages V₁ and V₂, V₂ initially being zero, to a pair of test drops d₁ and d₂ in a drop stream to induce charges q₁ and q₂ on said drops; ii) electrostatically deflecting the drop d₁ out of the path of said drop stream, the remaining drops in said stream, including d₂, being received in an ink catcher; iii) measuring the drop stream charge Q, where Q = q₁ + q₂ + ..q n , as the stream enters the catcher; iv) incrementing V₂ and repeating steps i), ii) and iii) until Q = 0; v) calculating the actual induction coefficients I n using the values V₁ and V₂ when Q = 0.
Claim 8
Dependent Claim
29 words
A method according to Claim 7 and further characterised by the step of calculating In employing the formula: I n = α 1+ αV₁ V₂ -n , α=e -1/2
Claim 9
Independent Claim
157 words
A method according to any one of Claims 1 to 4 and further characterised by the step of measuring the induction coefficients I n including the substeps of: i) applying a voltage V to a first drop in a drop stream directed at an ink catcher to apply a charge q₁ to said first drop and to induce charges q₂, q₃ ...q n on succeeding drops; ii) measuring the stream charge Q₁ where Q₁ = q₁ + q₂ +...q n as the drop stream enters the catcher; iii) repeating step i); iv) electrostatically deflecting the first drop out of the drop stream path, the remaining drops in said stream passing to the catcher; v) measuring the drop stream charge Q₂, where Q₂ = q₂+q₃+...q n , as the drop stream enters the catcher; vi) calculating the actual induction coefficients I n using the formula: I n = α 1- αQ₁ Q₂ -n , α = e -1/2
Claim 10
Dependent Claim
153 words
An ink jet printer including an ink supply (10), a nozzle (12), stimulation means acting on the nozzle to create a stream of ink drops, a charge tunnel (14, 16) to which voltages V n are applied by a programmable controller (18) thereby to charge selected drops in said stream, deflection plates (22, 24) for deflecting charged drops and an ink catcher (28)for receiving uncharged drops, characterised by also comprising: a system for field adjustment of calibrated charge tunnel voltages V n to reduce printing distortions of a printer, the system including; means for measuring the actual value of the induction coefficients, I m for said printer; and means for altering the calibrated voltages V n by a factor related to the difference between β m , the factory calibrated induction coefficients, and I m to obtain adjusted voltages Φ n ; said programmable controller employing the adjusted voltages Φ n for printing.
Claim 11
Dependent Claim
37 words
A printer according to Claim 10 and further characterised by the voltages V n being altered according to the formula: Φ n = V n + (I₁ - β ₁) V n-1 for a first order correction.
Claim 12
Dependent Claim
56 words
A printer according to Claim 10 or Claim 11 and further characterised by the voltages V n and n being stored in a memory element associated with said printer in the form of a default voltage table and a corrected voltage table; said controller printing from the corrected voltage table rather than the default voltage table.
Claim 13
Dependent Claim
47 words
A printer according to any one of Claims 10 to 12 and further characterised by the voltages V n being altered according to the formula: Φ n = V n + (I₁ - β ₁) V n-1 + [(I₂ - β ₂) - β ₁(I₁-β₁)] V n-2
Claim 14
Dependent Claim
46 words
A printer according to any one of Claims 10 to 13 and further characterised by the means for measuring including: a drop charge sensor positioned to detect the charges on drops in said stream, the output of said sensor being provided to said means for altering.
Claim 15
Dependent Claim
22 words
A printer according to Claim 14 and further characterised by said sensor being positioned between said charge tunnel and said deflection plates.
Claim 16
Dependent Claim
20 words
A printer according to Claim 14 and further characterised by said sensor being positioned in proximity to the ink catcher.
Claim 17
Dependent Claim
60 words
A printer according to any one of Claims 10 et 16 and further characterised by the means for altering including said programmable controller which receives the value I m and β m and calculates the adjusted voltages, Φ n according to the formula: Φ n = V n + (I₁ - β ₁) V n-1 for a first order correction.
References Cited (Backward Citations)
No citation records indexed.
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