US3863249A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic fluid display device
Assignee: Motorola Solutions Inc
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Filing: 1973-07-30
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Granted: 1975-01-28
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Expires: 1993-07-30
Abstract
Abstract A fluid display device includes a housing comprising a pair of blocks joined at first surfaces. One of the blocks is transparent and the other is opaque. A plurality of display elements is provided in the device, each such display element including a plurality of cavities formed in the first surface of the transparent block. An opaque magnetic liquid having a predetermined surface tension characteristic and a clear, immiscible liquid fill the cavities, respectively. A light reflecting layer on the first surface of the opaque block is aligned with one of the cavities in the transparent block for viewing through the last-mentioned block from the second surface thereof. Channels are provided between the cavities to permit the flow of the magnetic fluid therebetween and separate passages are provided which extend between the non-adjacent ends of the cavities for communication therebetween, through which the clear fluid is transferred between the cavities. An electromagnet assembly is mounted in the second surface of the opaque block and includes a plurality of coils wound about a core. Core legs extend toward the cavities, predetermined ones thereof being adjacent predetermined ones of the cavities. Energization of selected coils moves the magnetic fluid between the cavities to block or reveal the light reflecting layer, respectively, thereby to change the state of the display element of the device. The force of the moving magnetic fluid forces the clear liquid through the passages for transfer to the other cavities. Each element has two conditions and remains in each of these conditions without provision of power for maintenance. The surface tension of the magnetic fluid and the size of the channels and passages, chosen accordingly, ensures the bistability of the elements. The device is position insensitive as well. The state of the elements of the device may be determined also without viewing, since the permeability of the magnetic core portion adjacent the cavities whereat the magnetic fluid is located, is different than that of the core portions adjacent those cavities having no magnetic fluid located therein. This changes the inductance in an associated coil. The sensing of the impedance of the coil thus provides a determination of the state of the element.
Inventors
- 👤 Emery E Olah
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 00:48
CPC Classifications
G; G02; G02B; G02B26/00; G02B26/004; G09; G09F; G09F9/00; G09F9/30; G09F9/37; G09F9/375
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
153 words
A fluid display device including a housing having means defining a pair of cavities therein, means defining a channel connecting said cavities for communication therebetween, an opaque fluid having a predetermined surface tension characteristic provided in one of said cavities, a clear fluid provided in the other one of said cavities, said opaque fluid including magnetic particles suspended therein and said clear fluid being immiscible, and magnetic field producing means mounted adjacent said housing for providing a magnetic field of a predetermined strength to cause said magnetic fluid and clear fluid to be moved through said channel into the other of said cavities, respectively, said channel having a predeterminedly sized opening such that said opaque magnetic fluid having said predetermined surface tension characteristic remains in the cavity into which it has been moved despite the removal of the predetermined magnetic field by said magnetic field producing means and the position of said housing.
Claim 2
Dependent Claim
153 words
A fluid display device including a housing having means defining a pair of cavities therein, means defining a channel connecting said cavities for communication therebetween, an opaque fluid having a predetermined surface tension characteristic provided in one of said cavities, a clear fluid provided in the other one of said cavities, said opaque fluid including magnetic particles suspended therein and said clear fluid being immiscible, and magnetic field producing means mounted adjacent said housing for providing a magnetic field of a predetermined strength to cause said magnetic fluid and clear fluid to be moved through said channel into the other of said cavities, respectively, said channel having a predeterminedly sized opening such that said opaque magnetic fluid having said predetermined surface tension characteristic remains in the cavity into which it has been moved despite the removal of the predetermined magnetic field by said magnetic field producing means and the position of said housing.
Claim 3
Dependent Claim
79 words
A fluid display device as claimed in claim 1 wherein said channel means is provided along adjacent, opposing sides of said cavities and wherein said housing further include means defining a separate passage extending between non-adjacent sides of said cavities so that upon application of said magnetic field, the magnetic fluid is transferred between cavities through one of said channel and passage and said clear fluid is transferred between cavities through the other one of said channel and passage.
Claim 4
Dependent Claim
132 words
A fluid display device as claimed in claim 2 wherein said magnetic field producing means includes an electromagnet assembly having a core of magnetizable material with at least three core legs extending therefrom and first and second coils each wound about said core between a pair of said core legs, the energization of said first coil causing said first and second core legs to be polarized oppositely, thereby to produce a first magnetic field for moving said magnetic fluid from a first one of said cavities to the other of said cavities and the energization of said second coil causing said second and third legs to be polarized oppositely, thereby to produce a second magnetic field for moving said magnetic fluid from said other cavity to said first one of said cavities.
Claim 5
Dependent Claim
236 words
A fluid display device as claimed in claim 2 wherein said housing further includes means defining a third cavity provided adjacent one of said pair of cavities, means defining a second channel dimensioned similarly to said first-mentioned channel formed between said third cavity and said one cavity of said pair for communication therebetween and means defining a second passage, separate from said channels and said first-mentioned passage, extending between said one cavity of said pair of cavities aNd said third cavity, wherein said one cavity of said pair is substantially equal in volume to the sum of the volumes of said other cavity of said pair and said third cavity, wherein the volume of magnetic fluid provided in said device is equal to that required to fill said one cavity of said pair and wherein said magnetic field producing means provides a first magnetic field to transfer the magnetic fluid out of said one cavity of said pair through said channels into the other of said cavities of said pair and said third cavity, respectively, and second and third magnetic fields to transfer said magnetic fluid back from said other of said pair of cavities and said third cavity to said one cavity of said pair, said clear fluid being transferred simultaneously between said one cavity of said pair and said other one of said cavities of said pair and said third cavity, through said passages.
Claim 6
Dependent Claim
92 words
A fluid display device as claimed in claim 1 wherein said housing comprises a block of transparent material and wherein said means defining said pair of cavities in said housing further include a light reflecting wall portion mounted adjacent a first one of said cavities and a non-reflecting wall portion adjacent the second one of said pair of cavities, so that upon moving said opaque fluid from said first to said second one of said pair of cavities, said light reflecting wall portion is visible to one viewing said fluid display device.
Claim 7
Dependent Claim
297 words
A fluid display device including in combination: a housing formed of a first transparent block portion and a second opaque block portion joined together along first surfaces thereof, at least one display element provided in said housing, said display element including means defining a plurality of cavities formed in the first surface of said transparent block portion, means defining channels between adjacent sides of predetermined ones of said cavities, respectively, formed in the first surface of said transparent block portion, means defining passages between non-adjacent sides of said predetermined ones of said cavities formed in the first surface of said transparent block portion, means defining a visible light emitting area formed along the first surface of said opaque block portion in alignment with a predetermined one of said cavities formed in said transparent block portion and being visible through said last-mentioned block portion, an opaque fluid including magnetic particles suspended therein having a predetermined surface tension characteristic provided in predetermined ones of said cavities, a clear fluid provided in the other of said cavities, said display element thereby assuming a first stable condition, and magnetic field producing means mounted adjacent said housing for providing a magnetic field of a predetermined strength for transferring said magnetic fluid through said channels from said predetermined ones of said cavities to other predetermined ones of said cavities and simultaneously to transfer said clear fluid through said passages from said other cavities to predetermined other ones of said cavities, thereby to operate said display element to a second stable condition, said opaque fluid being received in said one predetermined cavity for blocking the view of said light emitting area in one of said stable conditions and being removed therefrom to reveal said light emitting area in the other of said stable conditions.
Claim 8
Dependent Claim
297 words
A fluid display device including in combination: a housing formed of a first transparent block portion and a second opaque block portion joined together along first surfaces thereof, at least one display element provided in said housing, said display element including means defining a plurality of cavities formed in the first surface of said transparent block portion, means defining channels between adjacent sides of predetermined ones of said cavities, respectively, formed in the first surface of said transparent block portion, means defining passages between non-adjacent sides of said predetermined ones of said cavities formed in the first surface of said transparent block portion, means defining a visible light emitting area formed along the first surface of said opaque block portion in alignment with a predetermined one of said cavities formed in said transparent block portion and being visible through said last-mentioned block portion, an opaque fluid including magnetic particles suspended therein having a predetermined surface tension characteristic provided in predetermined ones of said cavities, a clear fluid provided in the other of said cavities, said display element thereby assuming a first stable condition, and magnetic field producing means mounted adjacent said housing for providing a magnetic field of a predetermined strength for transferring said magnetic fluid through said channels from said predetermined ones of said cavities to other predetermined ones of said cavities and simultaneously to transfer said clear fluid through said passages from said other cavities to predetermined other ones of said cavities, thereby to operate said display element to a second stable condition, said opaque fluid being received in said one predetermined cavity for blocking the view of said light emitting area in one of said stable conditions and being removed therefrom to reveal said light emitting area in the other of said stable conditions.
Claim 9
Dependent Claim
281 words
A fluid display device as claimed in claim 6 wherein said one display element includes first, second and third cavities, said first and second cavities being joined between adjacent edges thereof by a first channel and the second and third cavities being joined between adjacent edges thereof by a second channel, said first and second cavities also being joined between non-adjacent edges thereof by a first separate passage and said second and third cavities also being joined between non-adjacent edges thereof by a second separate passage thereby providing a circuitous path for the flow of said fluids, wherein tHe sum of the volume of said first and third cavities is substantially equal to the volume of said second cavity, wherein said opaque fluid is provided in said first and third cavities in said first stable state and in said second cavity in said second stable state, wherein said light emitting area is formed along the first surface of said opaque block portion in alignment with said second cavity and wherein said magnetic field producing means includes an electromagnet assembly, said electromagnet assembly being energizable to produce a first magnetic field means for transferring said opaque fluid through said first and second channels from said first and third cavities to said second cavity, said clear fluid being transferred from said second cavity through said passages to said first and third cavities, respectively, and to produce a second magnetic field means for transferring said opaque fluid through said first and second channels from said second cavity to said first and third cavities, said clear fluid being transferred through said first and second passages from said first and third cavities to said second cavity.
Claim 10
Dependent Claim
55 words
A fluid display device as claimed in claim 7 wherein the second cavity of said display element is elongated in shape and wherein said device includes seven of said display elements positioned to form a figure eight symbol, said device displaying numerals from 0 to 9 depending upon the condition of said seven display elements.
Claim 11
Dependent Claim
189 words
A fluid display device as claimed in claim 6 wherein said display element includes first and second cavities joined between adjacent edges thereof by a channel formed therebetween, and joined at non-adjacent edges thereof by a separate passage to provide a circuitous path for the flow of said fluids, wherein said cavities are substantially equal in volume, wherein said opaque fluid is provided in said first cavity in said first stable state and in said second cavity in said second stable state, wherein said light emitting area is formed along the first surface of said opaque block portion in alignment with said second cavity and wherein said magnetic field producing means includes an electromagnet assembly energizable to produce a first magnetic field for transferring said opaque fluid through said channel from said first to said second cavity, said clear fluid being transferred from said second to said first cavity through said passage, and to produce a second magnetic field to transfer said opaque fluid through said channel from said second to said first cavity, said clear fluid being transferred through said passage from said first to said second cavity.
Claim 12
Dependent Claim
128 words
A fluid display device as claimed in claim 6 wherein said magnetic field producing means includes an electromagnet assembly comprising magnetizable core means having a plurality of core legs extending therefrom toward said fluid receiving cavities, the number of core legs being one greater than the number of fluid filled cavities, so that a pair of said core legs is positioned adjacent each one of said cavities and a plurality of coils wound about said core between said core legs, predetermined ones of said coils being energizable to produce first magnetic field means to operate said display element to said first stable condition and other predetermined ones of said coils being energizable to produce second magnetic field means to operate said display element to said second stable state.
Claim 13
Dependent Claim
71 words
A fluid display device as claimed in claim 10 further including means for sensing the condition of said display element, said means including impedance sensing means having an alternating current source coupled to a predetermined one of said coils and current sensing means, said impedance sensing means indicating the change in condition of said coil depending upon the location of said opaque magnetic fluid with respect to said associated core legs.
Claim 14
Dependent Claim
217 words
A fluid display device as claimed in claim 7 wherein said electromagnet assembly includes a magnetizable corE body mounted on said opaque block adjacent said cavities, said core including first, second, third and fourth core legs extending therefrom, said first and second core legs being located adjacent said first cavity, said second and third core legs being located adjacent said second cavity and said third and fourth core legs being located adjacent said third cavity, and three coils wound about said core each between a pair of said core legs, said first coil wound between said first and second core legs, said second coil wound between said second and third core legs and said third coil wound between said third and fourth core legs, said second coil being energized to produce opposite polarity poles at said second and third core legs to create a magnetic field for attracting said magnetic fluid from said first and third cavities toward said second cavity and said first and third coils being energized to produce opposite polarity poles at said first and second, and third and fourth core legs, respectively, with said second and third core legs being of like polarity, to create magnetic fields for moving said magnetic liquid from said second cavity to said first and third cavities, respectively.
Claim 15
Dependent Claim
183 words
A fluid display device as claimed in claim 9 wherein said electromagnet assembly includes a magnetizable core body mounted on said opaque block adjacent said cavities, said core including first, second and third core legs extending therefrom, said first and second core legs being positioned adjacent said first cavity and said second and third core legs being positioned adjacent said second cavity, and first and second coils wound about said core, each between a pair of said core legs, said first coil being wound between said first and second core legs and said second coil being wound between said second and third core legs, said first coil being energized to produce opposite polarity poles at said first and second core legs to create a first magnetic field for attracting said magnetic fluid to move the latter from said second to said first cavity and said second coil being energized to produce opposite polarity poles at said second and third core legs to create a second magnetic field for attracting said magnetic fluid, to move the latter from said first to said second cavity.
References Cited (Backward Citations)
US3648269A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-27 | 1978-07-29 | 1979-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-27 | 1982-07-29 | 1983-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-27 | 1986-07-29 | 1987-01-28 | $7700.00 | Window Closed / Lapsed |