Electrophotography – Image formation – Transfer
Reexamination Certificate
1999-09-02
2001-06-12
Braun, Fred L (Department: 2852)
Electrophotography
Image formation
Transfer
C399S302000, C399S306000
Reexamination Certificate
active
06246856
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a printer or copier device for performance-adapted, monochrome and/or chromatic, single-sided or both-sided printing of a recording medium.
2. Description of the Related Art
In electrophotographic color printers having high printing quality as disclosed, for example, by European Patent Document EP-A1-0 629 931, there is the problem that the same length of time is always required for producing a printed page given both a monochrome printing mode as well as given a chromatic printing mode. This means that was is referred to as the performance, i.e. the speed efficiency of the printer, is based on full color printing. When such a printer is utilized in a mixed printing operation, then it is usually the monochrome printing that occurs. Given electrophotographic high-performance printing with 200 pages/minute or higher, the print jobs to be processed contain a majority of monochrome printouts. Only a small portion of the print job is chromatic. Thus, for example, it can occur that a plurality of black-and-white successive pages are printed within a print job and that a full color image must then be printed, for example when producing a brochure. When the standard color printing devices are utilized for production of such a brochure, then they are relatively slow, since, as already stated, the printing performance is based on the color printing performance. Such color printer devices are also complicated and cost-intensive and inefficiently utilized for mixed operation.
Color printer devices with which single-color or two-color can be printed at high speed are disclosed, for example, by U.S. Pat. No. 5,526,107. In the known color printer device, continuous form paper is supplied to a transfer printing location of a photoconductive cylinder that comprises respective electrophotographic units for producing differently colored toner images on two surfaces. The continuous form paper is printed with a first color on the front side at the transfer printing location, the continuous form paper is subsequently deflected and supplied to a printing location at the same photoconductive cylinder lying opposite the transfer printing location and is printed on the backside of the paper.
German Patent Document A-176 18324 also discloses that color printing be performed in that a plurality of developer stations allocated to the individual color separations of the color image are arranged along a photoconductor. The developer stations can be individually mechanically activated, namely in that they are brought into mechanical contact with the photoconductor band. For producing color printing, individual color separations are generated on the photoconductor band and are then transferred onto a collector in the form of an intermediate transfer drum. This intermediate transfer drum then transfers the full color image that has arisen by the superimposition onto a single page.
It is also known to employ a transfer band instead of the transfer cylinder, as disclosed by European Patent Document A2-0 320 995.
What all known color printer devices have in common is that their performance is based on the color printing speed and that the printer devices are therefore uneconomical to utilize for mixed operation.
SUMMARY OF THE INVENTION
An object of the present invention is to offer a multi-color printer or copier device with high printing performance that is especially suited for mixed operation and whose performance is based on the maximum printing output in monochrome operation.
This object is achieved by a printer or copier device for performance-adapted, monochrome and/or chromatic single-sided or both-sided printing of a recording medium, whereby the device comprises:
at least one electrophotography module for generating toner images on a continuous photoconductor with the assistance of a plurality of developer stations that are arranged along the surface of the photoconductor and that are individually switchable, each of the developer stations being respectively allocated to a single color separation toner image;
at least one transfer module with an endless transfer band that comprises a transfer region for accepting toner images from the electrophotography module and a controllable transfer printing region for the transfer printing of toner images onto the recording medium, whereby, in a transfer printing condition of the transfer module, the transfer band contacts the recording medium and, in a collecting condition of the transfer module, the transfer band is spaced from the recording medium;
a transport channel comprising a controllable transfer means for the recording medium and having electrophotography and transfer modules arranged at one side or both sides of the transport channel;
a control means coupled to the electrophotography module, to the transfer module and to the transport means that controls the electrophotography module, transfer module and transport means such that,
for printing a recording medium moved through the transfer printing region in a start-stop mode in a first operating condition of the apparatus, the color separation toner images, in the collecting condition of the transfer module, are serially transferred from the electrophotography module onto the transfer band and an exactly registered collective image is thus produced on the transfer band, this then being transferred in the transfer printing state of the transfer module onto the recording medium, and
for printing a recording medium moved continuously through the transfer printing region in a second operating condition of the apparatus in the transfer printing status of the transfer module, the toner images are directly transferred from the electrophotography module onto the transfer band and are transferred farther therefrom onto the recording medium without collecting.
Advantageous embodiments of the invention are provided by a printer or copier device having at least one electrophotography module allocated to the front side of the recording medium with an appertaining transfer module and at least one electrophotography module allocated to the back side of the recording medium with an appertaining transfer module, whereby the transfer modules are arranged at both sides of the transport channel. The transfer modules are either arranged lying opposite one another in the transfer printing region, or the transfer modules have their transfer printing region arranged offset relative to one another along the transport channel.
The printer or copier device may have at least one fixing module following the transfer printing region in the conveying direction of the recording medium and having a thermal fixing means arranged therein. The fixing module for thermal fixing of the image follows every transfer printing region of the transfer modules arranged offset relative to one another as viewed in the conveying direction of the recording medium. The thermal fixing means may be an infrared fixing means that works in a non-contacting fashion with the recording medium. In particular, the thermal fixing means for fixing single sheets may include a conveyor belt that accepts the single sheet with its side that has not yet been tonered or already fixed and an infrared means lying opposite the conveyor belt for fixing the loose toner images.
The transport means includes motor-driven conveyor rollers for the recording medium. A delivery module is provided for the recording medium which serves as a web storing means in the fashion of a loop-forming means. A post-processing module may be provided following the fixing module or modules and having a separating means arranged therein.
In a preferred embodiment, the developer stations are individually replaceable in the printer or copier. As an improved development, the electrophotography module may include a plurality of image-generating devices each with a character generator and at least one developer station. The transfer band may be a cold transfer band, whereby the transfer of the toner images ensues
Bergmann Peter
Ferber Otto
Kopp Walter
Manzer Hans
Schreieder Josef
Braun Fred L
Oce Printing Systems GmbH
Schiff & Hardin & Waite
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