US5155498A
Expired / Lapsed
US
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Method of operating an ink jet to reduce print quality degradation resulting from rectified diffusion
Assignee: Xerox Corp
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Filing: 1991-03-06
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Granted: 1992-10-13
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Expires: 2011-03-06
Abstract
Abstract A drop-on-demand ink jet print head (9) has an ink pressure chamber (22) coupled to a source of ink (11) and an ink drop ejecting orifice (103) with an ink drop ejection orifice outlet (14). An acoustic driver (36), in response to a driver signal (100), produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop ejecting orifice (103) and the ink jet ejection orifice outlet (14) of the ink jet print head (9). In accordance with the present invention, controlling the operation of the ink jet print head (9) with a particular drive signal reduces print quality degradation resulting from rectified diffusion, which is the growth of air bubbles dissolved in the ink from the repeated application of pressure pulses to the ink residing within the ink pressure chamber (22) of the ink jet print head (9), such pressure pulses causing the application of pressures below ambient pressure. This method of controlling the operation of the ink jet print head (9) applies pressure below ambient pressure to the ink residing within the ink pressure chamber (22) of the ink jet print head (9) at magnitudes less than the threshold pressure magnitude that leads to the air bubble growth.
Inventors
- 👤 Joy Roy
- 👤 Douglas M. Stanley
- 👤 James D. Buehler
- 👤 Ronald L. Adams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:52
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/015; B41J2/04; B41J2/045; B41J2/04501; B41J2/04516; B41J2/04581; B41J2/04588; B41J2/135; B41J2/14; B41J2002/14387; B41J2202/00; B41J2202/01; B41J2202/12
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
224 words
In an ink jet print head of the type having an ink pressure chamber having a volume coupled to a source of hot melt ink and a driver for expanding the volume of the ink pressure chamber when subjected to a first electrical pulse and for contracting the volume of the ink pressure chamber when subjected to a second electrical pulse to eject a drop of ink from the ink jet print head, and in which growth of air bubbles in ink in the ink pressure chamber occurs when pressure within the ink pressure chamber is below ambient pressure and in negative pressure terms is greater than or equal to a threshold pressure amount, a method comprising: applying the first electrical pulse to the driver, the first electrical pulse being of a character that the pressure within the ink pressure chamber in negative pressure terms is less than the threshold pressure amount throughout the application of the first electrical pulse, thereby to inhibit the growth of air bubbles within the ink pressure chamber; terminating the first electrical pulse and allowing the driver to remain in a wait period state; and, following the wait period state, applying to the driver the second electrical pulse to contract the volume of the ink pressure chamber and eject a drop of ink from the ink jet print head.
Claim 2
Dependent Claim
224 words
In an ink jet print head of the type having an ink pressure chamber having a volume coupled to a source of hot melt ink and a driver for expanding the volume of the ink pressure chamber when subjected to a first electrical pulse and for contracting the volume of the ink pressure chamber when subjected to a second electrical pulse to eject a drop of ink from the ink jet print head, and in which growth of air bubbles in ink in the ink pressure chamber occurs when pressure within the ink pressure chamber is below ambient pressure and in negative pressure terms is greater than or equal to a threshold pressure amount, a method comprising: applying the first electrical pulse to the driver, the first electrical pulse being of a character that the pressure within the ink pressure chamber in negative pressure terms is less than the threshold pressure amount throughout the application of the first electrical pulse, thereby to inhibit the growth of air bubbles within the ink pressure chamber; terminating the first electrical pulse and allowing the driver to remain in a wait period state; and, following the wait period state, applying to the driver the second electrical pulse to contract the volume of the ink pressure chamber and eject a drop of ink from the ink jet print head.
Claim 3
Dependent Claim
25 words
The method of claim 1 in which the first electrical pulse has an amplitude and the character of the first electrical pulse includes the amplitude.
Claim 4
Dependent Claim
36 words
The method of claim 2 in which the second electrical pulse has an amplitude, and the amplitude of the first electrical pulse is at least 1.15 times greater than the amplitude of the second electrical pulse.
Claim 5
Dependent Claim
30 words
The method of claim 1 in which the first electrical pulse has a time duration at an amplitude and the character of the first electrical pulse includes the time duration.
Claim 6
Dependent Claim
44 words
The method of claim 1 in which the first electrical pulse has a rise time and a fall time each having a duration and the character of the first electrical pulse includes the duration of at least one of the rise and fall times.
Claim 7
Dependent Claim
66 words
The method of claim 1 in which the ink jet print head has a dominant acoustic resonant frequency and in which the frequency spectrum of a drive signal comprised of the first and second electrical pulses separated by the wait period state has a minimum energy content at a frequency that is substantially equal to the dominant acoustic resonant frequency of the ink jet print head.
Claim 8
Dependent Claim
39 words
The method of claim 1 in which the first electrical pulse has rise and fall times and a time duration at an amplitude excluding rise and fall times, and the character of the first electrical pulse includes the amplitude.
Claim 9
Dependent Claim
28 words
The method of claim 1 in which the first electrical pulse is a trapezoidal wave form with an exponentially rising leading edge and an exponentially decaying trailing edge.
Claim 10
Dependent Claim
56 words
The method of claim 1 in which the print head ejects multiple ones of the drops at speeds of at least 4 meters per second in response to multiple ones of the second electrical pulse at a drop repetition rate of at least 7 kilohertz without the growth of air bubbles within the ink pressure chamber.
Claim 11
Dependent Claim
140 words
In an ink jet print head of the type having an ink pressure chamber having a volume coupled to a source of hot melt ink and a driver for controlling the volume of the ink pressure chamber in response to an electrical pulse and in which growth of air bubbles in ink in the ink pressure chamber occurs when pressure within the ink pressure chamber is below ambient pressure and in negative pressure terms is greater than or equal to a threshold pressure amount, a method comprising: applying the electrical pulse to the driver, the electrical pulse being of a character that the pressure within the ink pressure chamber in negative pressure terms is less than the threshold pressure amount throughout the application of the electrical pulse, thereby to inhibit the growth of air bubbles within the ink pressure chamber.
Claim 12
Dependent Claim
140 words
In an ink jet print head of the type having an ink pressure chamber having a volume coupled to a source of hot melt ink and a driver for controlling the volume of the ink pressure chamber in response to an electrical pulse and in which growth of air bubbles in ink in the ink pressure chamber occurs when pressure within the ink pressure chamber is below ambient pressure and in negative pressure terms is greater than or equal to a threshold pressure amount, a method comprising: applying the electrical pulse to the driver, the electrical pulse being of a character that the pressure within the ink pressure chamber in negative pressure terms is less than the threshold pressure amount throughout the application of the electrical pulse, thereby to inhibit the growth of air bubbles within the ink pressure chamber.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-10-13 | 1996-04-13 | 1996-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-10-13 | 2000-04-13 | 2000-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-10-13 | 2004-04-13 | 2004-10-13 | $7700.00 | Window Closed / Lapsed |