US3863108A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic charge controller
Assignee: Imperial Chemical Industries Ltd
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Filing: 1974-01-04
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Granted: 1975-01-28
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Expires: 1994-01-04
Abstract
Abstract Method and apparatus for controlling the electrostatic charge density on a surface by generating an ion current adjacent the surface, partially screening the surface from the generated ion current, and controlling the magnitude and sign of the ion current passing to the surface by means of an applied bias voltage. A charge sensor/feed back system may be employed to control the bias voltage.
Inventors
- 👤 Anthony Reginald Blythe
- 👤 Wilson Reddish
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:25
CPC Classifications
H; H05; H05F; H05F3/00; H05F3/04; B; B29; B29C; B29C48/00; B29C48/03; B29C48/07; B29C48/08; B29C48/25; B29C48/88; B29C48/91; B29C48/911; B29C48/9135; B29C48/915; B29C48/9165
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
131 words
A method for reducing the electrostatic charge density on an electrostatically charged surface of a thermoplastic polymeric film comprising establishing a corona discharge to generate an ion current adjacent said electrostatically charged surface, partially screening the charged surface from said ion current, sensing the electrostatic charge density on the charged surface, generating a signal proportional to the sensed charge density, providing a bias voltage of less than 100 volts at a surface of the film remote from that exposed to the corona discharge to direct a proportion of the generated ion current onto the charged surface and employing said generated signal to control the bias voltage at a value such that the electrostatic charge density on the charged surface is reduced to less than 1 picocoulomb per square centimetre of surface.
Claim 2
Independent Claim
131 words
A method for reducing the electrostatic charge density on an electrostatically charged surface of a thermoplastic polymeric film comprising establishing a corona discharge to generate an ion current adjacent said electrostatically charged surface, partially screening the charged surface from said ion current, sensing the electrostatic charge density on the charged surface, generating a signal proportional to the sensed charge density, providing a bias voltage of less than 100 volts at a surface of the film remote from that exposed to the corona discharge to direct a proportion of the generated ion current onto the charged surface and employing said generated signal to control the bias voltage at a value such that the electrostatic charge density on the charged surface is reduced to less than 1 picocoulomb per square centimetre of surface.
Claim 3
Dependent Claim
27 words
A method according to claim 1 wherein the film of a thermoplastic polymeric material is selected from the group consisting of polycarbonates, polysulphones, polyamides, polyesters and polyolefins.
Claim 4
Dependent Claim
41 words
A method according to claim 1 comprising winding the treated film into a reel, sensing the electrostatic charge density of the reeled film, generating a signal proportional to the sensed charge density, and employing said signal to control the bias voltage.
References Cited (Backward Citations)
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 |