US3612665A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for forming a visual image of a latent magnetic image
Assignee: EIDP Inc
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Filing: 1969-05-09
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Granted: 1971-10-12
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Expires: 1989-05-09
Abstract
Abstract An apparatus and method for the visual observation of a latent magnetic image recorded on a magnetic member. The apparatus comprises: a nonmagnetic vessel, positioned above the magnetic member, having a broad shallow cavity containing magnetically active particles in a fluid or a vacuum; and a magnet to produce an external magnetic field. The magnetically active particles collect on the latent magnetic image to produce a visual image. If the external magnetic field is constant, the resolution of the visual image is increased. If the magnetic field is cycled between alternating polarity and is of sufficient intensity, the image reverses and the speed with which the visual image can follow changes in the latent magnetic image is increased.
Inventors
- 👤 Eustathios Vassiliou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:10
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/10; G11; G11B; G11B5/00; G11B5/74
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
187 words
An apparatus for the visual observation of a latent magnetic image recorded on a magnetic member in the form of active magnetic interfaces which comprises: a. a means for supporting said magnetic member; b. a nonmagnetic vessel containing a broad shallow cavity, said vessel being disposed above said magnetic member in a manner such that the magnetic field due to said latent magnetic image penetrates into said cavity; c. a quantity of magnetically active particles disposed within said cavity; and d. means for producing a magnetic field of alternating polarity within said cavity to supplement the magnetic field due to said latent magnetic image, said magnetic field of alternating polarity having a maximum field strength sufficient to cause sAid magnetically active particles to decorate the nonmagnetized areas of said magnetic member as well as a portion of said active magnetic interfaces thereby increasing the response speed of said apparatus to changes in said latent magnetic image, said magnetic field of alternating polarity having a frequency greater than the flicker rate that the eye can detect, whereby a visual image of said latent magnetic image can be produced.
Claim 2
Independent Claim
187 words
An apparatus for the visual observation of a latent magnetic image recorded on a magnetic member in the form of active magnetic interfaces which comprises: a. a means for supporting said magnetic member; b. a nonmagnetic vessel containing a broad shallow cavity, said vessel being disposed above said magnetic member in a manner such that the magnetic field due to said latent magnetic image penetrates into said cavity; c. a quantity of magnetically active particles disposed within said cavity; and d. means for producing a magnetic field of alternating polarity within said cavity to supplement the magnetic field due to said latent magnetic image, said magnetic field of alternating polarity having a maximum field strength sufficient to cause sAid magnetically active particles to decorate the nonmagnetized areas of said magnetic member as well as a portion of said active magnetic interfaces thereby increasing the response speed of said apparatus to changes in said latent magnetic image, said magnetic field of alternating polarity having a frequency greater than the flicker rate that the eye can detect, whereby a visual image of said latent magnetic image can be produced.
Claim 3
Dependent Claim
16 words
The apparatus of claim 1 wherein said magnetically active particles are contained in a gaseous atmosphere.
Claim 4
Dependent Claim
15 words
The apparatus of claim 1 wherein said magnetically active particles are contained in a vacuum.
Claim 5
Dependent Claim
15 words
The apparatus of claim 1 wherein said magnetically active particles are contained in a liquid.
Claim 6
Dependent Claim
16 words
The apparatus of claim 1 wherein said magnetically active particles are coated with a nonmagnetic material.
Claim 7
Dependent Claim
23 words
The apparatus of claim 1 further comprising means to produce a constant magnetic field component to said magnetic field cycled between alternating polarities
Claim 8
Dependent Claim
26 words
The apparatus of claim 1 wherein said means for producing a magnetic field of alternating polarity is an alternating current source with a direct current component.
Claim 9
Dependent Claim
32 words
The apparatus of claim 1 wherein said magnetically active particles are composed of magnetic materials selected from the group consisting of cobalt particles and mixtures of cobalt particles and magnetic Fe2O3 particles.
Claim 10
Dependent Claim
15 words
The apparatus of claim 1 wherein said magnetically active particles are coated particles of magnetite
Claim 11
Dependent Claim
18 words
The apparatus of claim 1 wherein said magnetically active particles are particles of magnetite coated with carnauba wax.
Claim 12
Dependent Claim
138 words
The apparatus of claim 1 wherein said magnetically active particles are coated particles of a ferromagnetic metal. 12 The apparatus of claim 1 wherein said means for supporting said magnetic member is adapted to move said magnetic member, whereby said visual image is a changing visual image. 13 The apparatus of claim 1 wherein said magnetic member is a stationary magnetic member and wherein said means adapted to hold said magnetic member is adapted to alter said latent magnetic image recorded on said magnetic member, whereby said visual image is a changing visual image. 14 The apparatus of claim 1 further comprising means for displaying said visual image on a screen. 15 The apparatus of claim 1 wherein said magnetic member is a magnetic member formed from the group of magnetic materials consisting of CrO2 and iron oxide.
Claim 13
Dependent Claim
201 words
A method of forming a visual image of a latent magnetic image recorded on a magnetic member in the form of active magnetic interfaces which comprises: a. positioning a suspension of magnetically active particles in a fluid above said magnetic member in a manner such that the magnetic field due to said latent magnetic image penetrates said suspension; and b. providing a magnetic field of alternating polarity within said suspension to supplement the magnetic field due to said latent magnetic image, said magnetic field of alternating polarity having a maximum field strength sufficient to cause said magnetically active particles to decorate the nonmagnetized areas of said magnetic member as well as a portion of said active magnetic interfaces thereby increasing the response speed of said suspension to changes in said latent magnetic image, said magnetic field of alternating polarity having a frequency greater than the flicker rate that the eye can detect, whereby a visual image of said latent magnetic image is formed. 17 The method of claim 16 wherein the step of positioning a suspension of magnetically active particles above said magnetic member comprises positioning a powder of magnetically active particles disposed in a gaseous atmosphere above said magnetic member.
Claim 14
Dependent Claim
17 words
The method of claim 16 further comprising the step of projecting said visual image on a screen.
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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) | 1974-10-11 | 1975-04-12 | 1975-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-11 | 1979-04-12 | 1979-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-11 | 1983-04-12 | 1983-10-12 | $7700.00 | Window Closed / Lapsed |