US3778690A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic copying machine
Assignee: COPY RES CORP
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Filing: 1972-03-16
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Granted: 1973-12-11
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Expires: 1992-03-16
Abstract
Abstract In a copying machine employing two conductive rollers to which zinc oxide coated copy paper is fed, the power source provides a DC voltage between the rollers that is derived from a frequency (of 25 kilocycles, for example) which is relatively high compared to line frequency. The relatively high frequency ripple that is on the DC output eliminates much of the problem with discernible lines on the end product. One of the two rollers has a rubber sleeve which is selected to provide a low capacitance such as 75 micro-microfarads. The resistance of the sleeve is such that a current flow of 50 microamperes is obtained with a 3,000 volt potential between the two rollers. The low capacitance means that when a sheet of copy paper is fed between the rollers, the change in the potential across the rubber sleeve and the change in current flow will occur very rapidly so that an even charge is applied on the copy paper. Because of the relatively high frequency employed, the ripple factor is kept low and the voltage magnitude applied is kept down to a point where the amount of ozone generated is minimized.
Inventors
- 👤 F Rothacker
- 👤 D Bujese
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 01:16
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/02; G03G15/0208; G03G15/0216; G03G15/0233
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
217 words
In a two-roller mechanism for applying a charge to coated copy paper wherein the copy paper passes between a first conductive roller and a second conductive roller having a dielectric sleeve thereon, the improvement comprising, pressure means to apply pressure between said first roller and said sleeve, the material of said sleeve being such that substantial area contact is established between said sleeve and whatever paper is fed between said sleeve and said first roller under said pressure established by said pressure means, said area of contact being sufficiently great to provide a current path that substantially eliminates the generation of ozone, the capacitance and resistance of said sleeve when positioned between the rollers and when subject to said pressure providing an electrical time constant sufficiently short in duration that the introduction of copy paper between the rollers results in a sufficiently rapid adjustment of the voltage division between the sleeve and the copy paper that the charge density in the leading portion of the copy paper is substantially equal in magnitude to the charge density in the trailing portion of the copy paper, said sleeve being mounted on said second roller such that said second roller applies a uniform potential at any one moment to the surface of said sleeve in contact with said second roller.
Claim 2
Dependent Claim
217 words
In a two-roller mechanism for applying a charge to coated copy paper wherein the copy paper passes between a first conductive roller and a second conductive roller having a dielectric sleeve thereon, the improvement comprising, pressure means to apply pressure between said first roller and said sleeve, the material of said sleeve being such that substantial area contact is established between said sleeve and whatever paper is fed between said sleeve and said first roller under said pressure established by said pressure means, said area of contact being sufficiently great to provide a current path that substantially eliminates the generation of ozone, the capacitance and resistance of said sleeve when positioned between the rollers and when subject to said pressure providing an electrical time constant sufficiently short in duration that the introduction of copy paper between the rollers results in a sufficiently rapid adjustment of the voltage division between the sleeve and the copy paper that the charge density in the leading portion of the copy paper is substantially equal in magnitude to the charge density in the trailing portion of the copy paper, said sleeve being mounted on said second roller such that said second roller applies a uniform potential at any one moment to the surface of said sleeve in contact with said second roller.
Claim 3
Dependent Claim
15 words
The improvement of claim 1 wherein said time constant is no greater than 5 milli-seconds.
Claim 4
Dependent Claim
30 words
The improvement of claim 1 wherein said resistance of said di-electric sleeve is great enough to limit the DC current level between said rollers to no more than 60 microamperes.
Claim 5
Dependent Claim
30 words
The improvement of claim 2 wherein said resistance of said di-electric sleeve is great enough to limit the DC current level between said rollers to no more than 60 microamperes.
Claim 6
Dependent Claim
14 words
The improvement of claim 1 wherein the material of said sleeve is a butadiene-acrylonitrile.
Claim 7
Dependent Claim
14 words
The improvement of claim 2 wherein the material of said sleeve is a butadiene-acrylonitrile.
Claim 8
Dependent Claim
14 words
The improvement of claim 3 wherein the material of said sleeve is a butadiene-acrylonitrile.
Claim 9
Dependent Claim
14 words
The improvement of claim 4 wherein the material of said sleeve is a butadiene-acrylonitrile.
Claim 10
Dependent Claim
77 words
The improvement of claim 1 further comprising: a DC power supply having its output across the rollers and having a relatively high frequency ripple current on its DC output, the relationship between a. the output capacity of said power supply, b. the capacity of the di-electric sleeve when subject to said pressure and c. the amplitude and frequency of the ripple providing a substantially even charge density along the surface of copy paper introduced between the rollers.
Claim 11
Dependent Claim
17 words
The improvement of claim 9 wherein the frequency of said ripple current is at least 10 kilohertz.
Claim 12
Dependent Claim
21 words
The improvement of claim 10 wherein the magnitude of the ripple is less than 5 percent of the DC voltage level.
Claim 13
Dependent Claim
15 words
The improvement of claim 9 wherein said time constant is no greater than 5 milli-seconds.
Claim 14
Dependent Claim
30 words
The improvement of claim 12 wherein said resistance of said di-electric sleeve is great enough to limit the DC current level between said rollers to no more than 60 microamperes.
Claim 15
Dependent Claim
17 words
The improvement of claim 13 wherein the frequency of said ripple current is at least 10 kilohertz.
Claim 16
Dependent Claim
21 words
The improvement of claim 14 wherein the magnitude of the ripple is less than 5 percent of the DC voltage level.
Claim 17
Dependent Claim
14 words
The improvement of claim 13 wherein the material of said sleeve is a butadiene-acrylonitrile.
Claim 18
Dependent Claim
14 words
The improvement of claim 15 wherein the material of said sleeve is a butadiene-acrylonitrile.
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) | 1976-12-10 | 1977-06-11 | 1977-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-10 | 1981-06-11 | 1981-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-10 | 1985-06-11 | 1985-12-11 | $7700.00 | Window Closed / Lapsed |