US3632971A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-limiting electric hair curler heater
Assignee: Texas Instruments Inc
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Filing: 1970-01-27
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Granted: 1972-01-04
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Expires: 1990-01-27
Abstract
Abstract A hair curler employing a heater element having a steeply sloped positive temperature coefficient (PTC) of resistance at temperatures above an anomaly temperature of ceramic or polymer material is disclosed. The heater combines a fast warmup time due to a low base resistivity with a slow cool down time due to the relatively massive heat sink which the heater forms. The sharp rise in resistance at temperatures above an anomaly temperature limits the current levels and hence heat generation at elevated temperatures thereby obviating the need for additional control means such as thermostats and the like.
Inventors
- 👤 Charles D Flanagan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:13
CPC Classifications
A; A45; A45D; A45D2/00; A45D2/36
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
134 words
An electrically heated hair curler comprising a generally cylindrical outer shell, a plurality of hair engaging fingers distributed over the outer-peripheral surface of the shell and extending outwardly therefrom, heat storage means mounted within the shell in close heat transfer relation with the shell, the heat storage means including an elongated annular heating element tightly fitted into the outer shell to optimize heat transfer between the heating element and the shell, the heating element having a steeply sloped PTC at temperatures above an anomaly temperature, means for making electrical connection with the element and conductive layers located on the inner and outer peripheral surfaces of the annular heating element, a ring-shaped portion of the layers being of increased thickness to facilitate making electrical connection with said means for making electrical connection with the element.
Claim 2
Dependent Claim
134 words
An electrically heated hair curler comprising a generally cylindrical outer shell, a plurality of hair engaging fingers distributed over the outer-peripheral surface of the shell and extending outwardly therefrom, heat storage means mounted within the shell in close heat transfer relation with the shell, the heat storage means including an elongated annular heating element tightly fitted into the outer shell to optimize heat transfer between the heating element and the shell, the heating element having a steeply sloped PTC at temperatures above an anomaly temperature, means for making electrical connection with the element and conductive layers located on the inner and outer peripheral surfaces of the annular heating element, a ring-shaped portion of the layers being of increased thickness to facilitate making electrical connection with said means for making electrical connection with the element.
Claim 3
Dependent Claim
24 words
A hair curler according to claim 1 in which the heating element and the heat storage means is formed out of the same element.
Claim 4
Dependent Claim
24 words
A hair curler according to claim 2 in which the heating and heat storage means is formed of a polymer filled with carbon particles.
Claim 5
Dependent Claim
26 words
A hair curler according to claim 2 in which the heating and heat storage means is formed of a ceramic-type material doped with a rare earth.
Claim 6
Dependent Claim
117 words
A hair curler according to claim 1 in which a recessed area is provided in the curler adjacent each ring-shaped portion of the layers and said means for making electrical conneCtion with the element including a base of electrically insulative material, a recessed seat portion formed in the base, two concentric ring terminals mounted in the base and extending from the surface thereof into the recessed seat portion area, the rings being sized so that when the curler is placed in the seat portion the ring terminals will extend into the respective recessed areas of the base so that the ring-shaped portion of the conductive layers will mate with the ring terminals to effect electrical connection therewith.
Claim 7
Dependent Claim
47 words
A hair curler according to claim 5 in which the ring terminals are slightly conical in shape with the imaginary apex of one ring located toward one side of the base and the imaginary apex of the other ring located toward an opposite side of the base.
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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) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |