Photocopying – Projection printing and copying cameras – Combined with or convertible to a contact printer
Patent
1986-06-24
1987-10-13
Moses, R. L.
Photocopying
Projection printing and copying cameras
Combined with or convertible to a contact printer
355 3SH, 355 24, 271186, 271303, G03G 2100
Patent
active
046995030
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an electrophotographic information printer with a xerographic reproduction system, comprising a sheet supply with at least two sheet magazines each having a respective sheet discharge slit at one end of the magazine, a sheet feeding path defined by sheet feeding and sheet guide means and having a first path section from the sheet discharge slit in an arbitrary magazine to an image transfer station, in which one side of a sheet is brought into contact with a toner powder image on a moved photo conductor, a second path section from the image transfer station to a fixing device and a third path section from the fixing device to a sheet receiving device, a sheet reversing device being positioned at the third path section in connection with the sheet feeding path, said sheet reversing device comprising a substantially vertical chamber with a downwardly facing sheet entrance and sheet discharge opening and a reversing device comprising on one hand an arrangement composed of three parallel rollers with a first and a second roller nip, the inlet side of the first roller nip facing said third section of the sheet feeding path, while the second roller nip has inlet and outlet sides facing said chamber and a sheet return path, respectively, extending from the reversing device to a supply slit provided in one of said magazines opposite the sheet discharge slit and, on the other hand, a selectively operable blocking member for blocking the sheet passage between the roller arrangement and said chamber.
In this respect information printers comprise duplicating devices in the form of copying machines in which the sheet printing is effected by reproduction from an original document, as well as printers for use in connection with word or data processing systems in which the sheet printing is carried out on the basis of electronic character information transmitted from the word or data processing system.
In most of the prior copying machines duplex sheet printing can be effected only in that the sheets printed on one side are manually moved from the copy discharge chamber and then placed upside down in the sheet supply of the machine. In electronically controlled, non-xerographic information printers it is generally not possible to print on both sides of the sheet.
U.S. Pat. No. 4,385,825 discloses a copying machine for duplex sheet printing of the above mentioned type in which the reversing device at the part of the sheet feeding path located after the fixing device is adapted either to direct a sheet into the reversing chamber or to let the sheet pass through both roller nips in said arrangement of three rollers by blocking the supply opening of the reversing chamber by means of a first blocking member, and after the sheet has passed said rollers it may be directed by a second blocking member either to a copy collecting bin or to one end of a sheet conveyor from the opposite end of which the sheet by means of a further blocking member may either be returned to said one magazine or to a sheet sorting apparatus.
By the various reversing possibilities it is inter alia the purpose of said prior construction to make it possible to supply sheets to said sheet collecting bin as well as to the return magazine with a selected sheet side facing downwardly, whereby producing e.g. either sheets printed on both sides or sheets with more prints on the same side, and likewise sheets may optionally be supplied to the collecting bin with the printed sides in the same order or in reverse order in relation to the printed sides of the original document.
The reversing arrangement is however complicated due to the considerable number of selectively operable blocking members. Further, the fact that sheet reversing in the vertical chamber is necessary not only when printing on both sheet sides but also when copies shall be supplied to the collecting bins with the printed pages in the same order as the original document involves an undesired extension of the sheet passing period of this ordinarily desired function, thereb
REFERENCES:
patent: 4305655 (1981-12-01), Gamblin
patent: 4385825 (1983-05-01), Kaneko
patent: 4453841 (1984-06-01), Bobick et al.
patent: 4534643 (1985-08-01), Watanabe
patent: 4536078 (1985-08-01), Ziehm
patent: 4537497 (1985-08-01), Masuda
patent: 4561765 (1985-12-01), Masuda
patent: 4569582 (1986-02-01), Hyltoft
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