Typewriting machines – Including control of format by programmed-control-system
Reexamination Certificate
2001-02-26
2003-06-17
Hirshfeld, Andrew H. (Department: 2854)
Typewriting machines
Including control of format by programmed-control-system
C400S059000, C400S283000, C101S071000
Reexamination Certificate
active
06579019
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention lies in the field of printing. The invention relates to an apparatus for printing, in particular, a franking and/or a addressing machine, with a printing head that is held displaceably on a printing-head mounting. In order to achieve the relative movement between the printing head and the medium to be printed, the mounting is configured to be movable, during printing, between a first longitudinal position and a second longitudinal position in a first direction with respect to a base element. Also provided is a first offsetting device that allows the printing of printing images offset to one another transversely to the first direction. The offsetting device is configured for offsetting the printing head relative to the printing-head mounting from a first transverse position into at least one second transverse position spaced from the first transverse position transversely to the first direction. In order to hold the printing head in the first or the second transverse position during printing, a holder for holding the printing head in the respective position is provided.
Within the meaning of the invention, the term “printing head” refers to all types of printing devices that can generate a printing image on a medium. In other words, the term, on one hand, includes printing devices employing any desired printing techniques. Nor is it to be restricted to the component that directly generates the printing image, but may additionally embrace further components that are required for generating the printing image. The components may be, for example, ink reservoirs, etc.
A prior art apparatus is disclosed, for example, in European Patent Application EP 0 933 210 A2. In the apparatus described there, the printing head is disposed displaceably in a mounting guided by a guide rod. For printing, the mounting and, therefore, the printing head are moved in a first direction, to be precise, parallel to the guide rod.
When a first printing image has been generated, the printing head is offset relative to the mounting perpendicularly to the first direction, in order, in a further step, to generate a second printing image, with the printing head being moved in the first direction in the opposite sense. The offset of the second printing image to the first printing image is such that the two printing images overlap one another at most in the edge region in which they are contiguous to one another transversely to the first direction. It is, thereby, possible to generate by a printing head an entire printing image of which the dimension transverse to the first direction, that is to say transverse to the printing direction, corresponds approximately to double the printing width of the printing head.
In the prior art apparatus, the offsetting device is disposed on the mounting and is configured as a linear drive that acts on the printing head. Naturally, the linear drive also assumes the function of a holder.
Such a configuration has a disadvantage that the use of the linear drive for holding the printing head in the respective transverse position necessitates a relatively complicated activation of the drive, if appropriate even a position control, in order to ensure exact positioning of the printing head. Moreover, the drive must deliver a particular holding moment in both directions of movement, in order to ensure exact positioning during the printing operation.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an apparatus for guiding a printing head that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that, at low outlay, ensures exact and reliable positioning of the printing head during printing.
With the foregoing and other objects in view, there is provided, in accordance with the invention, an apparatus for printing, including a base element, a printing-head mounting moveably connected to the base element, a printing head displaceably connected to the printing-head mounting, the printing-head mounting configured to move, during printing, between a first longitudinal position and a second longitudinal position in a given direction with respect to the base element to effect a relative movement between the printing head and a medium to be printed, an offsetting device for printing images offset to one another transverse to the given direction, the offsetting device configured to offset the printing head relative to the printing-head mounting from a first transverse position into at least one second transverse position spaced from the first transverse position in a direction transverse to the given direction, and a holder for holding the printing head in at least one of the first transverse position and the second transverse position during printing, the holder having at least one first holding device and at least one second holding device, each of the at least one first holding device and the at least one second holding device having at least one stop for limiting movement of the printing-head transverse to the given direction. Preferably, the printing apparatus is a franking machine.
The invention is based on the technical teaching that a particularly simple apparatus with transverse positioning of the printing head, the transverse positioning conforming well to the accuracy requirements, is obtained when the means for holding the printing head in the respective transverse position has at least one first holding device and one second holding device that respectively include at least one stop for limiting the printing-head movement transversely to the first direction.
In accordance with another feature of the invention, at least one holding device has a stop with a stop surface, and the stop is disposed on the printing-head mounting.
In a refinement according to the invention, it is necessary merely for the relative positions of the stop regions disposed on the printing head and the relative positions of the stops cooperating with these to be within specific predetermined tolerances in order to ensure sufficiently exact positioning.
Contact between the stop regions disposed on the printing head and the stops may, in such a case, be punctiform or linear, but, for reasons of wear, it preferably takes place over an area in order to obtain low local surface pressure during contact.
The stops may be disposed fixedly on the apparatus, for example, on the base element. During the movement of the printing head during printing, the respective stop regions on the printing head then brush over the respective stop cooperating with them. Preferably a stop surface of the stop of at least the first holding device is disposed on the printing-head mounting. One advantage is that such a stop is largely free of wear because, during printing, it does not experience any movement relative to the printing head and, therefore, as a rule, has no appreciable tangential forces acting upon it, but, instead, mainly normal forces. Consequently, it does not undergo any appreciable frictional wear.
In accordance with a further feature of the invention, the there is provided a force member for providing a contact force, and at least one holding device is configured to hold the printing head in at least one of the first and second transverse positions by the contact force acting on the stop.
The first holding device holding the printing head in the corresponding transverse position can ensure the transverse positioning of the printing head during printing by positive connection. In order to ensure reliable positioning of the printing head during printing in a simple way, the first holding device is configured preferably for holding the printing head in the associated transverse position by a first contact force acting on the stop.
For such a purpose, in preferred variants of the apparatus according to the invention, a spring device for achieving the first contact force by spring action is provided. The spring device can act directly on the printing head and prestress the prin
Ansell Iain
Brace Steven Roland
Francotyp-Postalia AG & Co.
Greenberg Laurence A.
Hirshfeld Andrew H.
Mayback Gregory L.
Stemer Werner H.
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