US4531110A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Negative temperature coefficient thermistors
Assignee: Nokia Bell Labs
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Filing: 1981-09-14
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Granted: 1985-07-23
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Expires: 2001-09-14
Abstract
Abstract Inexpensive Mn or Mg ferrites may be used as negative temperature coefficient thermistors. Fabrication of devices with the desired high temperature coefficients is facilitated by a processing method which forms a thin layer of oxidized and high resistivity material on a low resistivity layer of ferrite material.
Inventors
- 👤 David W. Johnson, Jr.
- 👤 Murray Robbins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:15
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/04; H01C7/042; H01C7/043; H01C7/046; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082; Y10T29/49085
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
131 words
A thermistor comprising a first layer of material having the nominal atom composition M 1-x Fe 2+x-z R z O 4 , where M is at least one element selected from the group consisting of Mn and Mg, x is greater than or equal to 0.0 and less than or equal to 0.3, R is selected from the group consisting of Al and Ti, z is greater than or equal to 0.0 and less than or equal to 1.2, and electrical contacts on opposed surfaces of said layer, and a second and a third layer of material having the composition M 1-x Fe 2+x-z R z O 4+ β, said β being greater than 0.0 and less than 0.2, said layers being disposed intermediate said first layer and said electrical contacts.
Claim 2
Dependent Claim
131 words
A thermistor comprising a first layer of material having the nominal atom composition M 1-x Fe 2+x-z R z O 4 , where M is at least one element selected from the group consisting of Mn and Mg, x is greater than or equal to 0.0 and less than or equal to 0.3, R is selected from the group consisting of Al and Ti, z is greater than or equal to 0.0 and less than or equal to 1.2, and electrical contacts on opposed surfaces of said layer, and a second and a third layer of material having the composition M 1-x Fe 2+x-z R z O 4+ β, said β being greater than 0.0 and less than 0.2, said layers being disposed intermediate said first layer and said electrical contacts.
Claim 3
Dependent Claim
133 words
A thermistor comprising a first layer of material having the nominal atom composition M 1-x Fe 2+x-z R z O 4 , where M is at least one element selected from the group consisting of Mn, Mg, Ni, Co, Cu and Zn, x is greater than or equal to 0.0 and less than or equal to 0.3, R is selected from the group consisting of Al and Ti, z is greater than or equal to 0.0 and less than or equal to 1.2, electrical contacts to opposed surfaces of said layer, a second and a third layer of material having the composition M 1-x Fe 2+x-z R z O 4+ β, said β being greater than 0.0 and less than 0.2, said layers being disposed intermediate said first layer and said electrical contacts.
Claim 4
Dependent Claim
133 words
A thermistor comprising a first layer of material having the nominal atom composition M 1-x Fe 2+x-z R z O 4 , where M is at least one element selected from the group consisting of Mn, Mg, Ni, Co, Cu and Zn, x is greater than or equal to 0.0 and less than or equal to 0.3, R is selected from the group consisting of Al and Ti, z is greater than or equal to 0.0 and less than or equal to 1.2, electrical contacts to opposed surfaces of said layer, a second and a third layer of material having the composition M 1-x Fe 2+x-z R z O 4+ β, said β being greater than 0.0 and less than 0.2, said layers being disposed intermediate said first layer and said electrical contacts.
Claim 5
Dependent Claim
19 words
A thermistor as recited in claim 2 in which said second layer has a thickness less than 100 μm.
Claim 6
Dependent Claim
14 words
A thermistor as recited in claim 1 or 2 in which M is Mg.
Claim 7
Dependent Claim
16 words
A thermistor as recited in claim 4 in which x is less than or equal to.
Claim 8
Dependent Claim
21 words
A thermistor as recited in claim 5 in which R comprises Ti and z is less than or equal to 1.2.
Claim 9
Dependent Claim
13 words
A thermistor as recited in claim 6 in which R further comprises Al.
Claim 10
Dependent Claim
36 words
A thermistor as recited in claim 7 in which said R comprises TiAl y , said y being greater than or equal to 0.0 and less than or equal to 0.2, said x being essentially 0.0.
Claim 11
Dependent Claim
26 words
A thermistor as recited in claim 5 in which z is essentially 0.0, and β is greater than 0.0 and less than or equal to x/2.
Claim 12
Dependent Claim
15 words
A thermistor as recited in claim 9 in which x is between 0.0125 and 0.05.
Claim 13
Dependent Claim
14 words
A thermistor as recited in claim 1 or 2 in which M is Mn.
Claim 14
Dependent Claim
26 words
A thermistor as recited in claim 11 in which z is essentially 0.0 and β is greater than 0.0 and less than or equal to x/2.
Claim 15
Dependent Claim
22 words
A thermistor as recited in claim 12 in which x is at least 0.0125 and less than or equal to approximately 0.2.
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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) | 1988-07-22 | 1989-01-21 | 1989-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-22 | 1993-01-21 | 1993-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-22 | 1997-01-21 | 1997-07-23 | $7700.00 | Window Closed / Lapsed |