US4436648A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrically conducting thermoplastic material, its manufacture, and resulting article
Assignee: AT&T Inc
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Filing: 1980-12-22
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Granted: 1984-03-13
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Expires: 2000-12-22
Abstract
Abstract ABS thermoplastic material is rendered electrically conducting by the inclusion of carbon particles. When manufactured by a process of dry mixing of ingredients, melting, and molding, the material has desirably low sheet resistance even at relatively low levels of carbon content (as is desirable in the interest of plastic formability). The new material may be used in the manufacture of electret microphones.
Inventors
- 👤 Sarwan K. Khanna
- 👤 Satya P. Khanna
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 02:04
CPC Classifications
H; H04; H04R; H04R19/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
94 words
Electret microphone comprising a molded thermoplastic component of which at least a portion is electrically conducting, the material of said at least a portion consisting essentially of an acrylonitrile butadiene styrene copolymer resin and carbon particles, carbon being contained in said material in a percentage by weight which is here designated as x and which is in the range of 5-20 weight percent of said material, and said material having electrical sheet resistance which, in the absence of surface metallization, is less than or equal to a value of 60,000/x 3 ohm per square.
Claim 2
Dependent Claim
94 words
Electret microphone comprising a molded thermoplastic component of which at least a portion is electrically conducting, the material of said at least a portion consisting essentially of an acrylonitrile butadiene styrene copolymer resin and carbon particles, carbon being contained in said material in a percentage by weight which is here designated as x and which is in the range of 5-20 weight percent of said material, and said material having electrical sheet resistance which, in the absence of surface metallization, is less than or equal to a value of 60,000/x 3 ohm per square.
Claim 3
Dependent Claim
29 words
Electret microphone of claim 1 in which said material comprises said resin and said carbon particles in a combined amount of at least 98 weight percent of said material.
Claim 4
Dependent Claim
29 words
Electret microphone of claim 1 in which carbon is contained in said material in a percentage x which is in the range of 7-12 weight percent of said material.
Claim 5
Dependent Claim
31 words
Electret microphone of claim 1 including an electrically nonconducting thermoplastic component which consists essentially of an acrylonitrile butadiene styrene copolymer resin and which is attached to said electrically conducting thermoplastic material.
Claim 6
Dependent Claim
22 words
Electret microphone of claim 4 in which said nonconducting thermoplastic material is attached to said electrically conducting thermoplastic material by two-shot molding.
References Cited (Backward Citations)
US3612778A
Cited
GB2000158B
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-13 | 1987-09-12 | 1988-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-13 | 1991-09-12 | 1992-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-13 | 1995-09-12 | 1996-03-13 | $7700.00 | Window Closed / Lapsed |