Electrophotography – Image formation – Transfer
Reexamination Certificate
1999-05-24
2001-06-26
Brase, Sandra (Department: 2852)
Electrophotography
Image formation
Transfer
C399S306000, C399S309000
Reexamination Certificate
active
06253054
ABSTRACT:
The invention relates to an electrophotographic printer for printing a final image carrier, having a transport means for transporting the final image carrier, having a first print unit for producing a first toner image by means of a first arrangement of colored particles on a first photoconductor, having at least one additional print unit for producing an additional toner image by means of a further arrangement of colored particles on a further photoconductor, and having a transfer means for the direct or indirect transfer of the first toner image from the first photoconductor and of the additional toner image from the additional photoconductor onto a surface segment on the front of the final image carrier.
In the following, a color separation is understood to be a toner image applied by a single developer station. A multicolor toner image accordingly results by means of the superposition of several color separations.
A printer of this type is known for example from the European Laid Open Print EP 0 659 569 A1. In the printer specified there, the first monochromatic toner image (color separation) is fixed before the second toner image, likewise monochromatic, is applied onto the already-fixed first toner image. A well-registered multicolor printing is not possible with the known printer, because it cannot be ensured that the two toner images are printed exactly on the same surface segment of the carrier material. By this means, the image elements of the first toner image and of the second toner image also cannot be oriented precisely to one another. The consequence is that undesired superpositions or empty spaces can occur between image elements of different toner images (registration errors). In the end, a high-quality color printing is not possible.
Given a graduated flat color printing, color falsifications and color fringe effects arise. In addition, in the printing of lines and characters, fuzzy and/or color-falsified image details arise in the area of the lines and characters.
In addition, the printer according to the cited laid open print is inflexible with respect to an adaptation to various print jobs. If for example printing is to take place with only one color, the second printer according to the cited laid open print is superfluous. In addition, with the printer according to EP 0 659 569 A1 selection can take place only from a color palette of four predetermined colors during printing.
In the Laid Open Print DE 41 10 348 A1, a multicolor printer is explained that contains four print units, each having a photoconductor. The toner containers of the print units are connected removably with the printer. In contrast, a removal of the print units themselves is not provided given use of the printer for its intended purpose.
The object of the invention is to indicate a printer which, with a relatively simple construction, enables a multicolor printing of high quality, and which can be adapted rapidly to various print jobs with respect to the number of colors, the combination of simultaneously printable colors, the toner colors used during printing (color palette), and with respect to registration between particular color separations.
This object is achieved by means of a printer having the features of patent claim
1
. The printer according to the invention has a module for housing the first print unit in a first receptacle and for housing the additional print unit in an additional receptacle. Since the receptacles are arranged in a module, the spatial distance between the receptacles is small. The receptacles are preferably arranged immediately alongside one another.
In the invention, the first receptacle and the additional receptacle have essentially the same construction. The identical construction of the receptacles ensures that printer units can be exchanged among one another, and that a useful number of print units are placed into the receptacles corresponding to the required print quality. An adaptation of further-developed or, respectively, newly developed print units is possible if in the design of these print units care is taken that they can be placed into the receptacles.
In the invention, at least one of the print units is placed removably into one of the receptacles, i.e., this print unit can easily be placed into the respective receptacle or, respectively, removed from this receptacle. Any measure known to those skilled in the art, such as for example snapping or locking of the respective print unit into the receptacle, may be used here. By means of this measure, it is achieved that the printer according to the invention can be adapted rapidly, i.e., with few manual operations, to various print jobs, in that the removable print unit is removed or put into place, or, respectively, is exchanged for another print unit. Moreover, a changing of developer stations in the print unit, a refilling of toner and the execution of maintenance tasks is made easier, in that a print unit for the respective activity is removed from the module and is put into place again after termination of the activity.
The printer according to the invention can print the final image carrier, for example sheet-type material, preferably paper, directly or indirectly. In the case of indirect printing, an intermediate carrier is used onto which the toner images are transferred before they are finally transferred onto the final image carrier. If, in an embodiment of the invention, an intermediate carrier is used as carrier material, then among other things the superposition of the toner images of various print units can take place in a more precise fashion. The precision of registration is increased in this way, because the photoconductor and the intermediate carrier can be better synchronized than the photoconductor and the final image carrier. Moreover, the intermediate carrier is made of a material that is selected with respect to the interaction between the photoconductor and the intermediate carrier with respect to wear and chemical influence. By this means the photoconductor is worn away less and is worn more uniformly than would be the case given interaction with a final image carrier made for example of paper. In addition, an embodiment of the invention relates to a printer that is suitable for two-sided printing.
An embodiment of the invention relates in addition to an electrophotographic printer for multicolor printing having the features of patent claim
7
. This printer operates according to a method designated repeat printing in the following, in which the final image carrier or, respectively, the intermediate carrier is conveyed several times past a print unit that successively applies at least two toner images onto the same surface segment of the carrier material. If the toner image applied in a first printing step has colored particles of at least three colors, then it is ensured that at least image elements with these colors are oriented precisely to one another. If a further toner image, produced in a further printing step, is superposed on the first toner image, then there occur only registration errors between toner images of different print units. The result is that the print quality is increased. By means of the possibility of repeat printing, additional print units can be done without while maintaining the same print quality, whereby, however, a longer printing time, and thus a reduced number of pages printed per time unit, must be accepted. However, in the embodiment of the printer according to the invention an additional print unit can for example be placed into one of the print receptacles for example at a later time, so that the repeat printing can be replaced by multicolor printing in one pass.
A further embodiment of the invention relates to a printer having the features of patent claim
8
. This embodiment of the invention is based on the finding that during the application of a toner image the image elements do not deviate from their predetermined positions (well-registered printing). For this reason, in this embodiment of the invention colored particles of at le
Maess Volkhard
Schleusener Martin
Brase Sandra
Oce Printing Systems GmbH
Schiff & Hardin & Waite
LandOfFree
Modular electrophotographic multicolor printer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Modular electrophotographic multicolor printer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modular electrophotographic multicolor printer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2441637