US3751156A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic copying apparatus with means for preventing contamination of transfer material
Assignee: Agfa Gevaert AG
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Filing: 1972-10-24
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Granted: 1973-08-07
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Expires: 1992-10-24
Abstract
Abstract An electrostatic copying apparatus wherein an idler roller is movable toward and away from a rotary cylindrical xerographic surface carrying powder images for transfer onto a series of discrete sheets of transfer material. A scanning device is located upstream of the transfer station for powder images to effect a delay of the movement of roller toward the xerographic surface until the leading portion of an oncoming sheet is about to reach or reaches the transfer station and to effect a delay of the movement of roller away from the xerographic surface until the trailing portion of a sheet which is in the process of receiving a powder image is about to reach or moves only slightly beyond the transfer station. This insures that the powder images cannot be transferred onto the dielectric layer of the roller and prevents a contamination of the rear sides of next-following sheets.
Inventors
- 👤 R Szostak
- 👤 W Krueger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:54
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/14; G03G15/16; G03G15/1665; G03G15/167
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
171 words
In an electrostatic copying apparatus, the combination of a driven xerographic surface arranged to transport a series of powder images toward a transfer station; a countersurface normally spaced apart from said xerographic surface; means for transporting discrete sheets of transfer material along a path extending between said surfaces toward, through and beyond said transfer station; displacing means actuatable to move one of said surfaces toward the other surface to thereby effect at said station the transfer of a powder image from said xerographic surface onto one side of a sheet advancing through said station; and control means for preventing the transfer of powder images onto said countersurface, comprising scanning means adjacent to said path upstream of said transfer station and arranged to detect the leading portions of successive sheets, and time-delay means for delaying the actuAtion of said displacing means in response to detection of the leading portion of an oncoming sheet by said scanning means until the leading portion of said oncoming sheet at least closely approaches said transfer station.
Claim 2
Dependent Claim
171 words
In an electrostatic copying apparatus, the combination of a driven xerographic surface arranged to transport a series of powder images toward a transfer station; a countersurface normally spaced apart from said xerographic surface; means for transporting discrete sheets of transfer material along a path extending between said surfaces toward, through and beyond said transfer station; displacing means actuatable to move one of said surfaces toward the other surface to thereby effect at said station the transfer of a powder image from said xerographic surface onto one side of a sheet advancing through said station; and control means for preventing the transfer of powder images onto said countersurface, comprising scanning means adjacent to said path upstream of said transfer station and arranged to detect the leading portions of successive sheets, and time-delay means for delaying the actuAtion of said displacing means in response to detection of the leading portion of an oncoming sheet by said scanning means until the leading portion of said oncoming sheet at least closely approaches said transfer station.
Claim 3
Dependent Claim
23 words
The combination of claim 1, wherein said scanning means is closely adjacent to said transfer station and said one surface is said countersurface.
Claim 4
Dependent Claim
15 words
The combination of claim 1, wherein at least said countersurface is an endless cylindrical surface.
Claim 5
Dependent Claim
65 words
The combination of claim 1, wherein said one surface is said countersurface, said displacing means comprising carrier means supporting said countersurface and being movable between first and second positions in which said countersurface is respectively remote from and is located at said transfer station, and electromagnet means energizable with a delay determined by said time-delay means to move said carrier means to said second position.
Claim 6
Dependent Claim
19 words
The combination of claim 4, wherein said carrier means comprises lever means pivotable between said first and second positions.
Claim 7
Dependent Claim
17 words
The combination of claim 4, further comprising means for biasing said carrier means to said first position.
Claim 8
Dependent Claim
17 words
The combination of claim 4, wherein said carrier means tends to assume said first position by gravity.
Claim 9
Dependent Claim
132 words
The combination of claim 1, wherein said control means further comprises electric switch means arranged to be closed by said scanning means in response to detection of the leading portion of an oncoming sheet, said time-delay means comprising drive means having a rotary output element, rotary cam means, friction clutch means interposed between said output element and said cam means, and electromagnet means energizable in response to closing of said switch means to thereby permit said clutch means to rotate said cam means through a predetermined distance including a first portion which said cam means covers while maintaining said displacing means in deactivated condition and a second portion which said cam means covers while causing said displacing means to maintain said one surface in contact with a sheet at said transfer station.
Claim 10
Dependent Claim
20 words
The combination of claim 8, wherein said xerographic surface is a rotary cylindrical surface receiving torque from said drive means.
Claim 11
Dependent Claim
149 words
The combination of claim 8, wherein said cam means comprises a first projection, an angularly offset second projection and a cam face, said electromagnet means having an armature including first stop means located in the path of movement of said first projection in deenergized condition of said electromagnet means and second stop means located in the path of movement of said second projection in the energized condition of said electromagnet means, said displacing means comprising second electromagnet means energizable to move said one surface toward said other surface and said time-delay means further comprising normally open second electric switch means adjacent to said cam face, said cam face being arranged to close said second switch means and to thereby energize said second electromagnet means with a predetermined delay following disengagement of said first stop means from said first projection and before said second projection engages said second stop means.
Claim 12
Dependent Claim
121 words
The combination of claim 10, wherein said scanning means is arranged to effect an opening of said first mentioned switch means in response to detection of trailing portions of successive sheets whereby said first mentioned switch means deenergizes said first mentioned electromagnet means so that said second stop means is disengaged from said second projection and said clutch means is free to rotate said cam means to move said first projection into engagement with said first stop means, said cam face being arranged to effect an opening of said second switch means with a predetermined delay following the disengagement of said second stop means from said second projection and prior to reengagement of said first projection with said first stop means.
Claim 13
Dependent Claim
55 words
The combination of claim 1, wherein said scanning means is further arranged to detect the trailing portions of successive sheets and said time-delay means is arranged to delay the deactivation of said displacing means in response to detection of the trailing portions of sheets until the trailing portions at least closely approach said transfer station.
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) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |