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US4283438A
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Method for individually encapsulating magnetic particles
Assignee: Magnavox Electronic Systems Co
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Filing: 1979-12-26
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Granted: 1981-08-11
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Expires: 1999-12-26
Abstract
Abstract A method for encapsulating magnetic particles by enclosure within oil drops, mixing in an aqueous solution and dispersing the oil drops with the enclosed particles by application of an alternating magnetic field. The dispersed and oil-covered particles are microencapsulated with at least one type of polymer.
Inventors
- 👤 Lawrence L. Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 13:05
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44; B; B01; B01J; B01J13/00; B01J13/02; B01J13/04; G; G09; G09F; G09F9/00; G09F9/30; G09F9/37; G09F9/375; H01F1/01; H01F1/03; H01F1/032; H01F1/10; H01F1/11; H01F1/113
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
114 words
A method for encapsulating a preselected average number of magnetized particles which may be rotated within individual capsules for use in a magnetic particle display comprising the steps of: immersing the particles in a liquid internal phase; forming drops of the internal phase containing said particles; suspending said drops in a liquid continuous phase; applying a varying magnetic field to said suspension for dispersing said particles and forming smaller drops with a reduced number of particles in each drop, the frequency of said field variations being selected according to the desired number of particles in individual drops; microencapsulating individual ones of said drops to form capsules containing drops in which said particles are rotatable.
Claim 2
Independent Claim
114 words
A method for encapsulating a preselected average number of magnetized particles which may be rotated within individual capsules for use in a magnetic particle display comprising the steps of: immersing the particles in a liquid internal phase; forming drops of the internal phase containing said particles; suspending said drops in a liquid continuous phase; applying a varying magnetic field to said suspension for dispersing said particles and forming smaller drops with a reduced number of particles in each drop, the frequency of said field variations being selected according to the desired number of particles in individual drops; microencapsulating individual ones of said drops to form capsules containing drops in which said particles are rotatable.
Claim 3
Dependent Claim
34 words
The method of claim 1 including the step of progressively increasing the frequency of said field variations with time to progressively disperse said particles and progressively reduce the number of particles in individual drops.
Claim 4
Dependent Claim
41 words
The method of claim 2 wherein the step of progressively increasing the frequency of said field variations with time comprises increasing the field variations in discrete steps, each step being of an increased frequency over the frequency of the previous step.
Claim 5
Dependent Claim
29 words
The method of claim 3 wherein the frequency change between steps is less than 50% and there is a period corresponding to at least 200 cycles between each increase.
Claim 6
Dependent Claim
20 words
The method of claim 1 or 2 wherein the number of said particles in individual drops is reduced to one.
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein the step of applying a varying magnetic field comprises applying a field of alternating magnetic polarity.
Claim 8
Dependent Claim
31 words
A method according to claim 17 wherein the step of applying the alternating magnetic field further comprises varying the intensity and frequency of said field to control dispersal of the particles.
Claim 9
Dependent Claim
14 words
The method according to claim 7 wherein said internal phase is a transparent oil.
Claim 10
Dependent Claim
18 words
The method according to claim 8 wherein said continuous phase comprises water and a selected amount of surfactant.
Claim 11
Dependent Claim
27 words
The method according to claim 9 wherein the step of suspending the immersed particles further comprises dropping selected amounts of said immersed particles into said continuous phase.
Claim 12
Dependent Claim
12 words
The method according to claim 8 wherein said transparent oil comprises silicone.
Claim 13
Independent Claim
94 words
A method for dispersing a preselected average number of magnetized particles, the particles being enclosed in a discrete amount of internal phase to permit rotation of the particle therein, comprising the following sequential steps: 1. immersing the particles in a liquid internal phase; 2. suspending internal phase drops containing the immersed particles in a liquid continuous phase; and 3. applying a varying magnetic field to said suspension for dispersing said particles within their associated drops of said internal phase to control the size of the drops and the number of particles in the drops.
Claim 14
Independent Claim
94 words
A method for dispersing a preselected average number of magnetized particles, the particles being enclosed in a discrete amount of internal phase to permit rotation of the particle therein, comprising the following sequential steps: 1. immersing the particles in a liquid internal phase; 2. suspending internal phase drops containing the immersed particles in a liquid continuous phase; and 3. applying a varying magnetic field to said suspension for dispersing said particles within their associated drops of said internal phase to control the size of the drops and the number of particles in the drops.
Claim 15
Dependent Claim
16 words
The method according to claim 12 wherein said magnetic field is alternated during the dispersal step.
Claim 16
Dependent Claim
31 words
The method according to claim 13 wherein the step of applying the alternating magnetic field further comprises varying the intensity and frequency of said field to control dispersal of the particles.
Claim 17
Dependent Claim
14 words
The method according to claim 14 wherein said internal phase is a transparent oil.
Claim 18
Dependent Claim
12 words
The method according to claim 15 wherein said transparent oil comprises silicone.
Claim 19
Dependent Claim
27 words
The method according to claim 15 wherein the step of suspending the immersed particles further comprises dropping selected amounts of said immersed particles into said continuous phase.
Claim 20
Dependent Claim
18 words
The method according to claim 14 wherein said continuous phase comprises water and a selected amount of surfactant.
References Cited (Backward Citations)
US1407067A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-08-10 | 1985-02-09 | 1985-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-10 | 1989-02-09 | 1989-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-10 | 1993-02-09 | 1993-08-11 | $7700.00 | Window Closed / Lapsed |