Printing – Planographic – Lithographic plate making – and processes of making or using...
Reexamination Certificate
1999-06-14
2001-11-20
Funk, Stephen R. (Department: 2854)
Printing
Planographic
Lithographic plate making, and processes of making or using...
C101S147000, C101S148000, C101S453000, C101S465000, C101S466000, C101S478000, C101S456000
Reexamination Certificate
active
06318264
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a printing machine and an appertaining printing process. In offset printing, ever-greater parts of the operations for producing the printing form, the so-called pre-press stage, are performed with the assistance of electronic data processing. In the so-called computer-to-plate technique, all the operations from the production of the page layout to the digitally controlled imaging of the printing plate occur in the computer. The imaging of the printing plates takes place separately in a special exposure unit. In the so-called computer-to-press/direct imaging technique, as has been applied for the first time by Heidelberger Druckmaschinen AG in the GTO-DI, the exposure unit is transferred into the printing machine. The plates are exposed on the cylinder directly in the printing machine.
With regard to digital printing, techniques which go even further, also referred to as computer-to-print and computer-to-paper, include transferring digitized data from a computer to paper or other printing materials without a printing form with a fixed image via an intermediate carrier (e.g. photoconductor) or without any material intermediate stage. Corresponding printing techniques are, for example, electrophotography, thermal transfer printing or ink-jet printing and allow the motif to be changed during continuous printing, for example to produce a new printed image with each revolution of a form cylinder. In this regard, the production of a printing form is dispensed with, because each individual printing image is newly provided. However, this sacrifices the advantage of conventional processes such as offset printing, for example, of being able to print with high productivity from a constant printing form and of ensuring very high quality over the print run or edition.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a printing machine and an appertaining printing process with which it is possible both to print continuously from a master, such as is performed in offset printing, and also to change the motif during continuous printing, such as is possible, for example, in the case of electrophotography.
In accordance with the foregoing object of the invention, starting from a printing machine for the computer-to-press/direct imaging technique, there is consequently provided, in accordance with one aspect of the invention, a printing machine comprising a printing form, an optical imaging unit for directly imaging the printing form, and an inking unit for inking the printing form, the printing form having a surface for med of a material with wetting properties reversibly changeable between a state with a very small contact angle and a state with a relatively large contact angle, the state with a small contact angle being achievable by action of light having a wavelength shorter than a material-specific wavelength, and a cleaning device for cleaning the surface of the printing form.
In accordance with another feature of the invention, the material forming the surface contains TiO
2.
In accordance with a further feature of the invention, the printing form is selected from the group consisting of a form cylinder, a plate, and a strip.
In accordance with an added feature of the invention, the imaging unit is an area exposure unit for uniformly exposing the printing form to light having the wavelength shorter than the material-specific wavelength and for removing a molecular water layer on the printing form by light having a wavelength longer than the material-specific wavelength, as well as of suitable intensity and duration of action.
In accordance with an additional feature of the invention, the imaging unit is constructed for emitting light having a wavelength shorter than the material-specific wavelength.
In accordance with yet another feature of the invention, the light emitted by the imaging unit represents a negative image of the printing image.
In accordance with yet a further feature of the invention, the light emitted by the imaging unit represents a positive image of the printing image.
In accordance with yet an added feature of the invention, ink for inking the printing form by the inking unit is an ink selected from the group consisting of offset ink and offset-like ink.
In accordance with yet an additional feature of the invention, the printing machine of the invention includes a dampening unit for dampening the printing form.
In accordance with a second aspect of the invention, there is provided a printing process having the following process steps:
a) exposing a printing form having a surface formed of a material with wetting properties reversibly changeable between a state having a very small contact angle and a state having a relatively large contact angle, over at least a select area of the surface, to light having a wavelength shorter than a material-specific wavelength, so as to bring at least the select area of the surface into the state with the very small contact angle;
b) inking the printing form so that printing ink is accepted in image regions of the printing form;
c) transferring the printing ink from the printing form to printing material;
d) repeating processing steps b) and c) as required; and
g) cleaning the printing form.
In accordance with a third aspect of the invention, there is provided a printing process having the following successive process steps:
a) exposing a printing form having a surface formed of a material with wetting properties reversibly changeable between a state having a very small contact angle and a state having a relatively large contact angle, over the whole area of the surface, to light having a wavelength shorter than a material-specific wavelength, so as to bring the whole area of the surface into the state with the very small contact angle;
b) allowing a molecular water layer to form on the printing form;
c) irradiating image regions of the printing form with light having a wavelength longer than the material-specific wavelength, so as to remove the molecular water layer from image regions in the printing form;
d) inking the printing form so that printing ink is accepted in the image regions of the printing form;
e) transferring the printing ink from the printing form to printing material;
f) repeating processing steps d) and e) as required; and
g) cleaning the printing form.
In accordance with a fourth aspect of the invention, there is provided a printing process having the following successive process steps:
a) exposing a printing form having a surface formed of a material with wetting properties reversibly changeable between a state having a very small contact angle and a state having a relatively large contact angle, in non-image regions of the surface, to light having a wavelength shorter than a material-specific wavelength, so as to bring the non-image regions into the state with the very small contact angle;
b) allowing a molecular water layer to form on the printing form;
c) inking the printing form so that printing ink is accepted in the image regions of the printing form;
d) transferring the printing ink from the printing form to printing material;
e) repeating process steps c) and d) as required; and
f) cleaning the printing form.
In accordance with a fifth aspect of the invention, there is provided a printing process having the following successive process steps:
a) exposing a printing form having a surface formed of a material with wetting properties reversibly changeable between a state having a very small contact angle and a state having a relatively large contact angle, in image regions of the surface, to light having a wavelength shorter than the material-specific wavelength, so as to bring the image regions into the state with the very small contact angle;
b) inking the printing form so that printing ink is accepted in the image regions of the printing form;
c) transferring the printing ink from the printing form to printing material;
d) repeating process steps b) and c) as required; and
e) cleaning the printing f
D'Heureuse Walter
Kipphan Helmut
Schmitt-Lewen Martin
Funk Stephen R.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Lerner Herbert L.
Stemer Werner H.
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