US4633351A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for hydrodynamic magnetic recording
Assignee: AB Dick Co
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Filing: 1985-08-07
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Granted: 1986-12-30
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Expires: 2005-08-07
Abstract
Abstract Problems of wear and bounce created by imperfections in the surface of a magnetic recording medium, such as a chromium dioxide-coated drum, are circumvented by a hydrodynamic magnetographic imaging technique that provides the intended effective intimate contact between the recording head the magnetographic recording surface. A readily evaporatable liquid (e.g. water, alcohol, acetone) is applied to the surface of the drum slightly upstream of the location of the recording head, so as to create a liquid bearing against which the recording head is urged, and thereby intimately magnetically coupled with the surface of the drum, except for an extremely thin liquid film between the head and drum surface. As a result of this extremely thin liquid bearing, continuous pressure can be applied to the head to maintain the head in effective intimate contact with the surface of the recording medium without the fear of scratching the medium or causing wear on the head. Moreover, once the imaging process has been completed, and the recording head is retracted away from the drum (and the liquid bearing) the liquid bearing can be easily removed, as the liquid of which the bearing if formed, readily evaporates without leaving a residue, so that the drum is ready for the application of toner particles at a print station.
Inventors
- 👤 Andrew M. Bardos
- 👤 Jon E. Holmes
- 👤 Mark F. Duchesne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:25
CPC Classifications
G; G03; G03G; G03G19/00; G11; G11B; G11B21/00; G11B21/16; G11B21/20; G11B21/21; G11B23/00; G11B23/50; G11B5/00; G11B5/41; G11B5/48; G11B5/58; G11B5/60
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
66 words
For use in a recording apparatus wherein a prescribed characteristic of a recording medium is established by a transducer coupled therewith, a method of controlling the coupling of said transducer to said medium comprising the step of: forming a liquid bearing between the surface of said recording medium and said transducer, said liquid being of the type that will effectively readily evaporate without leaving a residue.
Claim 2
Dependent Claim
66 words
For use in a recording apparatus wherein a prescribed characteristic of a recording medium is established by a transducer coupled therewith, a method of controlling the coupling of said transducer to said medium comprising the step of: forming a liquid bearing between the surface of said recording medium and said transducer, said liquid being of the type that will effectively readily evaporate without leaving a residue.
Claim 3
Dependent Claim
33 words
A method according to claim 1, wherein and step (a) comprises forming a thin film a liquid consisting of one or more of water, alcohol, acetone, on the surface of said recording medium.
Claim 4
Dependent Claim
23 words
A method according to claim 1, wherein said recording medium includes a magnetically responsive recording material and said transducer comprises a magnetic head.
Claim 5
Dependent Claim
62 words
A method according to claim 3, wherein said recording apparatus comprises a magnetographic recording apparatus in which an image that has been formed on a magnetic recording medium is transferred to a further recording medium by the application of toner to said magnetic recording medium subsequent to the effective evaporation of said liquid bearing from the surface of said magnetic recording medium.
Claim 6
Dependent Claim
48 words
A method according to claim 3, further including the step of removing said liquid from the surface of said recording medium so that the surface of said recording medium is effectively free of said liquid prior to the application of recorded image transfer material to said recording medium.
Claim 7
Dependent Claim
52 words
A method according to claim 4, wherein said recording medium includes rotatable drum having a region of magnetic field responsive material at the surface thereof and said step comprises forming a thin liquid film on the surface of said drum in proximity of the position of said transducer relative to said drum.
Claim 8
Dependent Claim
50 words
A method according to claim 4, wherein said transducer is displaceable relative to the position at which a prescribed magnetic characteristic is established in said recording medium and said step includes forming said liquid bearing on the surface of said recording medium prior to locating said transducer at said position.
Claim 9
Dependent Claim
26 words
A method according to claim 7, including the step of moving said transducer relative to said position and thereby controlling the formation of said liquid bearing.
Claim 10
Dependent Claim
25 words
A method according to claim 8, wherein said bearing comprises a thin film of a liquid consisting of one or more of water, alcohol, acetone.
Claim 11
Dependent Claim
35 words
A method according to claim 1, further including the step of removing said liquid from the surface of said recording medium so that said surface of said recording medium is effectively free of said liquid.
Claim 12
Dependent Claim
101 words
For use in an apparatus wherein a prescribed characteristic of a recording medium is established by a transducer coupled therewith, arrangement for controlling the coupling of said transducer to said recording medium comprising: means for applying to said recording medium a liquid of the type that will effectively readily evaporate without leaving a residue; and means for causing a liquid film to be provided at at least that portion of said recording medium at which said transducer is coupled to establish said prescribed characteristic, so as to provide an effective cushion between said transducer and the surface of said recording medium.
Claim 13
Dependent Claim
101 words
For use in an apparatus wherein a prescribed characteristic of a recording medium is established by a transducer coupled therewith, arrangement for controlling the coupling of said transducer to said recording medium comprising: means for applying to said recording medium a liquid of the type that will effectively readily evaporate without leaving a residue; and means for causing a liquid film to be provided at at least that portion of said recording medium at which said transducer is coupled to establish said prescribed characteristic, so as to provide an effective cushion between said transducer and the surface of said recording medium.
Claim 14
Dependent Claim
37 words
An arrangement according to claim 11, wherein said liquid apply means includes means for applying a thin film of a liquid consisting of one or more of water, alcohol, acetone on the surface of said recording medium.
Claim 15
Dependent Claim
39 words
An arrangement according to claim 11, wherein said apparatus includes means for moving said recording medium relative to said transducer, said liquid film being carried past said transducer during the relative movement between said recording medium and said transducer.
Claim 16
Dependent Claim
41 words
An arrangement according to claim 13, wherein said liquid applying means comprises means for causing said liquid to be directed onto said recording medium and means for establishing the thickness of the liquid film that is formed on said recording medium.
Claim 17
Dependent Claim
23 words
An arrangement according to claim 11, wherein said recording medium includes a magnetically responsive recording material and said transducer comprises a magnetic head.
Claim 18
Dependent Claim
58 words
An arrangement according to claim 15, wherein said recording medium includes a rotatable cylindrically-shaped body having a region of magnetic field responsive material at the surface thereof, and said liquid applying means includes means for forming a thin liquid film on the surface of said body in proximity of the position of said transducer relative to said body.
Claim 19
Dependent Claim
62 words
An arrangement according to claim 11, wherein said recording apparatus comprises a magnetographic recording apparatus in which an image that has been formed on a magnetic recording medium is transferred to a further recording medium by the application of toner to said magnetic recording medium subsequent to the effective evaporation of said liquid bearing from the surface of said magnetic recording medium.
Claim 20
Dependent Claim
47 words
An arrangement according to claim 17, further including means for removing said liquid from the surface of said recording medium so that said surface of said recording medium is effectively free of said liquid prior to the application of recorded image transfer material to said recording medium.
Claim 21
Dependent Claim
38 words
An arrangement according to claim 17, wherein said transducer comprises a magnetic head displaceable relative to the position at which said magnetic head is operable to establish a prescribed magnetic characteristic in the surface of said recording medium.
Claim 22
Dependent Claim
33 words
An arrangement according to claim 19, wherein said liquid applying means includes means for controlling the application of said liquid to said recording medium in dependence upon the displacement of said magnetic head.
Claim 23
Dependent Claim
30 words
An arrangement according to claim 20 wherein said liquid applying means comprises means for applying a liquid consisting of one or more of water, alcohol, acetone to said recording medium.
Claim 24
Dependent Claim
34 words
An arrangement according to claim 11, further including means for removing said liquid from the surface of said recording medium so that said surface of said recording medium is effectively free of said liquid.
Claim 25
Dependent Claim
108 words
For use in a magnetographic recording apparatus having a magnetic field responsive recording medium the magnetic storage characteristics of which are established by magnetic field generating transducer coupled therewith, an arrangement for controlling the coupling of said transducer to the surface of said medium comprising: means for applying to said recording medium a liquid of the type that will effectively readily evaporate without leaving a residue; and means for causing a liquid film to be provided at at least that portion of said recording medium at which said transducer is coupled so as to provide an effective cushion between said transducer and the surface of said recording medium.
Claim 26
Dependent Claim
108 words
For use in a magnetographic recording apparatus having a magnetic field responsive recording medium the magnetic storage characteristics of which are established by magnetic field generating transducer coupled therewith, an arrangement for controlling the coupling of said transducer to the surface of said medium comprising: means for applying to said recording medium a liquid of the type that will effectively readily evaporate without leaving a residue; and means for causing a liquid film to be provided at at least that portion of said recording medium at which said transducer is coupled so as to provide an effective cushion between said transducer and the surface of said recording medium.
Claim 27
Dependent Claim
37 words
An arrangement according to claim 23, wherein said liquid applying means includes means for applying a thin film of a liquid consisting of one or more of water, alcohol, acetone on the surface of said recording medium.
Claim 28
Dependent Claim
39 words
An arrangement according to claim 23, wherein said apparatus includes means for moving said recording medium relative to said transducer, said liquid film being carried past said transducer during the relative movement between said recording medium and said transducer.
Claim 29
Dependent Claim
41 words
An arrangement according to claim 25, wherein said liquid applying means comprises means for causing said liquid to be directed onto said recording medium and means for establishing the thickness of the liquid film that is formed on said recording medium.
Claim 30
Dependent Claim
57 words
An arrangement according to claim 25, wherein said recording medium includes a rotatable cylindrically-shaped body having a region of magnetic field responsive material at the surface thereof, and said liquid applying means includes means for forming a thin liquid film on the surface of said in proximity of the position of said transducer relative to said body.
Claim 31
Dependent Claim
38 words
An arrangement according to claim 25, wherein said transducer comprises a magnetic head displaceable relative to the position at which said magnetic head is operable to establish a prescribed magnetic characteristic in the surface of said recording medium.
Claim 32
Dependent Claim
33 words
An arrangement according to claim 28, wherein said liquid applying means includes means for controlling the application of said liquid to said recording medium in dependence upon the displacement of said magnetic head.
Claim 33
Dependent Claim
47 words
An arrangement according to claim 23, further including means for removing said liquid from the surface of said recording medium so that the surface of said recording medium is effectively free of said liquid prior to the application of recorded image transfer material to said recording medium.
Claim 34
Dependent Claim
158 words
For use in a magnetographic recording apparatus having a magnetic field responsive recording medium the magnetic storage characteristics of which are established by a magnetic field generating transducer coupled therewith, an arrangement for proving effective intimate magnetic coupling between said transducer and the surface said recording medium irrespective of imperfections in the surface of said recording medium or the contamination thereof by foreign matter comprising: means for applying to the surface of said recording medium a liquid of the type that will effectively readily evaporate without leaving a residue; and means for causing a liquid film to be provided at at least that portion of said recording medium at which said transducer is coupled, so that, with said transducer being urged toward physical contact with the surface of said recording medium, said liquid film acts as a cushion to prevent said physical contact but to provide said effective intimate magnetic coupling between said transducer and said recording medium.
Claim 35
Dependent Claim
158 words
For use in a magnetographic recording apparatus having a magnetic field responsive recording medium the magnetic storage characteristics of which are established by a magnetic field generating transducer coupled therewith, an arrangement for proving effective intimate magnetic coupling between said transducer and the surface said recording medium irrespective of imperfections in the surface of said recording medium or the contamination thereof by foreign matter comprising: means for applying to the surface of said recording medium a liquid of the type that will effectively readily evaporate without leaving a residue; and means for causing a liquid film to be provided at at least that portion of said recording medium at which said transducer is coupled, so that, with said transducer being urged toward physical contact with the surface of said recording medium, said liquid film acts as a cushion to prevent said physical contact but to provide said effective intimate magnetic coupling between said transducer and said recording medium.
Claim 36
Dependent Claim
37 words
An arrangement according to claim 31, wherein said liquid applying means includes means for applying a thin film of a liquid consisting of one or more of water, alcohol, acetone on the surface of said recording medium.
Claim 37
Dependent Claim
39 words
An arrangement according to claim 31, wherein said apparatus includes means for moving said recording medium relative to said transducer, said liquid film being carried past said transducer during the relative movement between said recording medium and said transducer.
Claim 38
Dependent Claim
41 words
An arrangement according to claim 31, wherein said liquid applying means comprises means for causing said liquid to be directed onto said recording medium and means for establishing the thickness of the liquid film that is formed on said recording medium.
Claim 39
Dependent Claim
58 words
An arrangement according to claim 31, wherein said recording medium includes a rotatable cylindrically-shaped body having a region of magnetic field responsive material at the surface thereof, and said liquid applying means includes means for forming a thin liquid film on the surface of said body in proximity of the position of said transducer relative to said body.
Claim 40
Dependent Claim
47 words
An arrangement according to claim 31, further including means for removing said liquid from the surface of said recording medium so that the surface of said recording medium is effectively free of said liquid prior to the application of recorded image transfer material to said recording medium.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-12-29 | 1990-06-30 | 1990-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-29 | 1994-06-30 | 1994-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-29 | 1998-06-30 | 1998-12-30 | $7700.00 | Window Closed / Lapsed |