US4368952A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic display panel using reversal magnetism
Assignee: Pilot Corp
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Filing: 1980-12-10
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Granted: 1983-01-18
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Expires: 2000-12-10
Abstract
Abstract A magnetic reversal type display panel which provides clear display of records which can easily be raised by an erasure magnet. A liquid dispersion is sealed between two opposed surface plates, preferably in a cell structure. The liquid dispersion contains fine reversible magnetic display grains having magnetic poles of opposite signs tinged with different colors, a dispersion medium and a fine grain thickener. The fine reversible magnetic display grains have a residual magnetic moment within the range of 0.2 to 10 emu/g and a coercive force of not less than 500 oersteds and the liquid dispersion has a yield value of not less than 5 dynes/cm2.
Inventors
- 👤 Yasuzo Murata
- 👤 Hiroshi Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:50
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/09; G02F1/091; B; B43; B43L; B43L1/00; B43L1/008; G02F1/17; G02F1/172; G09; G09F; G09F9/00; G09F9/30; G09F9/37; G09F9/375
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
99 words
A magnetic reversal type display panel comprising: two opposed surface plates and a liquid dispersion sealed in the space between said surface plates, said liquid dispersion comprising fine reversible magnetic display grains having magnetic poles of opposite signs tinged with different colors, a dispersion medium and a fine grain thickener, wherein: (A) said fine reversible magnetic display grains have a residual magnetic moment within the range of from 0.2 to 10 emu/g and a coercive force of not less than 500 oersteds, and (B) said liquid dispersion has a yield value of not less than 5.0 dynes/cm 2 .
Claim 2
Dependent Claim
99 words
A magnetic reversal type display panel comprising: two opposed surface plates and a liquid dispersion sealed in the space between said surface plates, said liquid dispersion comprising fine reversible magnetic display grains having magnetic poles of opposite signs tinged with different colors, a dispersion medium and a fine grain thickener, wherein: (A) said fine reversible magnetic display grains have a residual magnetic moment within the range of from 0.2 to 10 emu/g and a coercive force of not less than 500 oersteds, and (B) said liquid dispersion has a yield value of not less than 5.0 dynes/cm 2 .
Claim 3
Dependent Claim
28 words
The magnetic display panel according to claim 1 wherein said fine reversible magnetic display grains have a particle size within the range of from 20 to 500 microns.
Claim 4
Dependent Claim
44 words
The magnetic display panel according to claim 1 wherein fine reversible magnetic display grains contain 1 to 40% by weight of at least one magnetic substrate selected from the group consisting of ferrites, rare earth cobalt compounds, cobalt-containing gamma iron oxide, and cobalt-containing magnetites.
Claim 5
Dependent Claim
33 words
The magnetic display panel according to claim 1 wherein the proportion of said fine reversible magnetic display grains to 100% by weight of the dispersion medium is not less than 4% by weight.
Claim 6
Dependent Claim
31 words
The magnetic display panel according to claim 1 wherein the proportion of the fine grain thickener to 100% by weight of the dispersion medium is not less than 0.5% by weight.
Claim 7
Dependent Claim
17 words
The magnetic display panel according to claim 1 wherein said dispersion medium comprises an aliphatic hydrocarbon solvent.
Claim 8
Dependent Claim
18 words
The magnetic display panel according to claim 1 wherein said fine grain thickener comprises finely powdered silicic acid.
Claim 9
Dependent Claim
17 words
The magnetic display panel according to claim 1 wherein said fine grain thickener comprises an olefin polymer.
Claim 10
Dependent Claim
26 words
The magnetic display panel according to claim 1 wherein said fine grain thickener comprises a copolymer of an olefin and a monomer copolymerizable with said olefin.
Claim 11
Dependent Claim
16 words
The magnetic display panel according to claim 1 wherein said fine grain thickener comprises a wax.
Claim 12
Dependent Claim
17 words
The magnetic display panel according to claim 1 wherein said fine grain thickener comprises a metal soap.
Claim 13
Dependent Claim
18 words
The magnetic display panel according to claim 1 wherein said fine grain thickener comprises an acyl-amino acid ester.
Claim 14
Dependent Claim
41 words
The magnetic display panel according to claim 1 wherein said fine grain thickener comprises finely powdered silicic acid and at least one member selected from the group consisting of olefin polymers, olefin copolymers, waxes, metal soaps and dextrin fatty acid esters.
Claim 15
Dependent Claim
21 words
The magnetic display panel according to claim 1 wherein at least one of said opposed surface plates is transparent and translucent.
Claim 16
Dependent Claim
30 words
The magnetic display panel according to any of claims 1-14 further comprising a multi-cell structure between said surface plates and wherein said liquid dispersion is sealed in said multi-cell structure.
Claim 17
Dependent Claim
36 words
The magnetic display panel according to any of claims 1-14 wherein one of said surface plates has formed therein a plurality of independent through cells and wherein said liquid dispersion is sealed in said through cells.
Claim 18
Dependent Claim
33 words
The magnetic display panel according to any of claims 1-14 further comprising a multi-cell plate disposed between said surface plates and wherein said liquid dispersion is sealed in cells of said multi-cell plates.
Claim 19
Dependent Claim
74 words
The magnetic panel according to claim 1 wherein the yield value of said dispersion medium is at least 5.0 dynes/cm 2 for a residual magnetic moment of said magnetic display grains in the range of 0.2 emu/g to 3.0 emu/g, and a gradually increasing yield value of from 5.0 dynes/cm 2 to 30 dynes/cm 2 for a residual magnetic moment of said magnetic display grains in the range of 3 emu/g to 10 emu/g.
References Cited (Backward Citations)
US3670323A
Cited
US4126854A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-01-17 | 1986-07-19 | 1987-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-17 | 1990-07-19 | 1991-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-17 | 1994-07-19 | 1995-01-18 | $7700.00 | Window Closed / Lapsed |