Photocopying – Including fiber optics
Patent
1983-08-11
1985-12-10
Braun, Fred L.
Photocopying
Including fiber optics
355 14TR, G03G 1516
Patent
active
045575835
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to xerography and, more particularly, to apparatus for transferring a toner image formed on a photoconductive coating to a print sheet.
2. Description of the Prior Art
The general state of the art with which the present invention is concerned is described in French Pat. No. 2,002,025 dated Oct. 3, 1969.
The operating principles of the apparatus with which the present invention is concerned are disclosed in U.S. Pat. No. 4,182,266 which describes an embodiment in which the sheets are held in place by register pins. Although the embodiment described in said patent is suited for laboratory uses, it cannot be used commercially because handling of the sheets is clumsy and time-consuming. Further, in order to obtain a sharp and well-defined final image, smudge-free transfer of toner is a pre-requisite and it is necessary to ensure that no movement takes place during transfer of toner between the transfer sheet and the coating and between the transfer sheet and the print sheet. The embodiment described in said patent does not meet this requirement. Additionally, the apparatus preferably should be compact and simple in construction and suitable for dealing with images of different formats.
The structure of the present invention provides an apparatus which satisfies the above requirements.
SUMMARY OF THE INVENTION
Apparatus and method for transferring a toned image from a photoconductive image arranged facing downwardly to a flexible transfer sheet whereas the transfer sheet is pressed progressively against the toned surface across the surface in one direction and peeled from the surface in an opposite direction, means mounting a print sheet on a drum and mounting the transfer sheet on the drum superposed on the print sheet, means for fixing one end of the transfer sheet, and exerting tension therein at its opposite end to resist but not prevent movement of the transfer sheet vertically upward and laterally unwinding same from the drum, electrically polarized roller means for applying pressure along first and second lines transversely of the receptor sheet and against the toned surface, means for moving the pressure lines along the toned surface maintaining the spacing and tautness of the transfer sheet between said pressure exerting means and the fixed end, one line of pressure being relieved at the end of the stroke and peeling the opposite end from the second line away from the surface along with the area thereof that was between the pressure lines, rewinding the transfer sheet on the drum over the print sheet and completing transfer from the transfer sheet to the print sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary perspective view of an apparatus constructed in accordance with the invention.
FIGS. 2 to 7 are schematic views illustrating the different phases in the transfer of toner from the photoconductive coating to the final print sheet, FIG. 2a illustrating the manner in which the transfer sheet and the print sheet are positioned initially on the drum and FIG. 4a illustrating schematically on an enlarged scale a portion on the coating, transfer sheet and pair of rollers.
FIG. 8 is a sectional view taken through a preferred embodiment of the apparatus of the invention showing moistening of the acceptor sheets.
FIG. 9 is a schematic cross-sectional view taken through said apparatus illustrating the manner in which a precisely predetermined quantity of toner solvent is applied to the photoconductive coating.
FIG. 10 is a schematic cross-sectional view of an alternate embodiment for moistening the sheets.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention described hereinafter is embodied in apparatus for transferring a toner image formed on a photoconductive coating to a print sheet. The apparatus includes a roller for respectively pressing the surface of a transfer sheet over the surface of said coating and peeling the transfer sheet off from said coating. The roller is maintained during the
REFERENCES:
patent: 3063351 (1962-11-01), Medley
patent: 3653891 (1972-04-01), Thourson et al.
patent: 3702482 (1972-11-01), Dolcimascolo et al.
patent: 3761174 (1973-09-01), Davidson
patent: 3862848 (1975-01-01), Marley
patent: 4182266 (1980-01-01), Alston
Alston Julia M.
Percic Milan
Schoonderbeek Hubertus J.
Braun Fred L.
Coulter Stork Patents B.V.
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