Applicator element and method for electrographic printing or copying using liquid colouring agents
AssigneeOce Printing Systems GmbH
InventorsMartin Berg, Martin Schleusener, Volkhard Maess
Life of this patent
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Abstract
There is described an applicator element for providing a layer of a liquid ink, in particular for inking a latent image carrier of a device for electrographic printing or copying, the surface of the applicator element (26) having a structure with a plurality of areas (78, 80, 86, 88), at which the detachment of droplets from the liquid layer is facilitated.
Claims83
Applicator element for providing a layer of liquid ink, in particular for inking a latent image carrier of a device for electrographic printing or copying, the surface of the applicator element (26) having a structure with a plurality of areas (78, 80, 86, 88), at which the detachment of droplets from the liquid layer is facilitated.
Applicator element according to one of the preceding claims, characterized in that DLC material is provided as a material layer.
Applicator element according to one of the preceding claims, characterized in that the structure of the surface of the applicator element includes a plurality of second areas (86) having a surface energy that is varied with respect to the remaining surface (80).
Applicator element according to one of the preceding claims, characterized in that a Ni layer or a layer of Ni alloy, preferably CrNi, is provided as a first material (76) and Teflon is provided as a second material, the Teflon material being preferably embedded into the Ni layer in the form of pellets.
Applicator element according to one of the preceding claims, characterized in that the structure of the surface of the applicator element (26) has a plurality of third areas (88) that are formed as microscopic elevations on the otherwise smooth surface.
Applicator element according to one of the preceding claims, characterized in that the first areas (78) and/or the second areas (86) and/or the third areas (88) repeat at a distance of 0.3 to 50 μm, preferably at a distance of 10 to 15 μm.
Applicator element according to one of the preceding claims, characterized in that the first areas (78) and/or the second areas (86) and/or the third areas (88) are arranged at regular distances or at stochastically distributed distances.
Applicator element according to one of the preceding claims, characterized in that with a regular arrangement of the first areas (78) and/or the second areas (86) and/or the third areas (88) the raster widths of these areas amount to 21.2 μm in order to correspond to the raster measure 1200 dpi.
Applicator element according to one of the preceding claims, characterized in that the change in material properties between the first areas (78) and/or the second areas (86) and/or the third areas (88) and the respectively remaining surface (80) takes place abruptly, preferably jump-wise.
Applicator element according to one of the preceding claims, characterized in that the change in material properties between the first areas (78) and/or the second areas (86) and/or the third areas (88) and the respectively remaining surface (80) takes place continuously, preferably without any distinctive jumps.
Applicator element according to one of the preceding claims, characterized in that the first areas (78) and/or the second areas (86) and/or the third areas (88), their distances to one another as well as their electrical conductivities, their surface energies or, respectively, their height with regard to the otherwise smooth surface are chosen such that droplets having a size of preferably 5 to 40 μm in diameter, in particular 10 to 20 μm in diameter, are formed.
Applicator element according to one of the preceding claims, characterized in that the first areas (78) and the third areas (88) are formed alternately.
Applicator element according to one of the preceding claims, characterized in that the local wave lengths of the first areas (78) and of the third areas (88) deviate from one another, the local wave length of the third areas (88) being at most one fifth of the local wave length of the first areas (78).
Applicator element according to one of the preceding claims, characterized in that the second areas (86) and the third areas (88) are combined with one another.
Applicator element according to one of the preceding claims, characterized in that the roller-shaped applicator element has a metallic cylindrical basic body (90), to which a cover layer (76) having a reduced conductivity and a medium surface energy, preferably in the range of 30 to 50 mN/m with a polar portion of >5 mN/m, preferably made of the material ceramics, is applied, in that this cover layer (76) has a regular cup structure with a resolution of 1200 dpi, in that the cups (84) are filled with a material, preferably Teflon, that has a lower surface energy and a lower conductivity than the material of the cover layer (76).
Applicator element according to one of the preceding claims, characterized in that the thickness of the cover layer (76) lies in the range of 1 to 500 μm.
Applicator element according to one of the preceding claims, characterized in that
- a latent image carrier (12) having a potential pattern (UP) corresponding to an image pattern to be printed is arranged opposite to the applicator element (26, 26a),
- an air gap (L) being provided between the liquid layer (48, 72) and the surface of the latent image carrier (12) that is opposed thereto,
- and, for inking the latent image on the latent image carrier (12), droplets (50) being transferred from the liquid layer (48, 72) onto the surface of the latent image carrier (12) by overcoming the air gap (L).
Applicator element according to one of the preceding claims, characterized in that the applicator element (26, 26a) is roller-shaped.
Applicator element according to one of the preceding claims, characterized in that the liquid layer (48) is formed as a layer having a plurality of droplets.
Applicator element according to one of the preceding claims, characterized in that the air gap (L) between the applicator element (26) and the latent image carrier (12) lies in the range of 50 to 1000 μm, preferably in the range of 100 to 200 μm.
Applicator element according to one of the preceding claims, characterized in that a bias potential (UB) in the form of a direct voltage is applied to the applicator element (26).
Applicator element according to one of the preceding claims, characterized in that the surface of the applicator element (26) is provided with a continuous liquid layer (72).
Applicator element according to one of the preceding claims, characterized in that the liquid ink and/or the liquid layer contains a nontoxic and/or nonflammable and/or non-odorous carrier liquid, preferably water.
Applicator element Device according to one of the preceding claims, characterized in that the liquid film is supplied to the surface of the applicator element (26, 26a) via a feed roller (36).
Applicator element according to one of the preceding claims, characterized in that the scoop roller (40) is designed as an anilox roller having a chamber doctor blade.
Applicator element according to one of the preceding claims, characterized in that a smooth liquid film is sprayed onto the feed roller.
Applicator element according to one of the preceding claims, characterized in that the applicator element dips with a portion thereof into a bath containing the ink, and in that the dosage of the accepted amount of liquid takes place via an elastic roll doctor that acts on the surface of the applicator roller.
Applicator element according to one of the preceding claims, characterized in that the inked image on the latent image carrier is treated such that at least a part of the carrier liquid escapes, preferably evaporates.
Applicator element according to one of the preceding claims, characterized in that an alternating force field is present in the air gap (L), said force field acting on the liquid layer (48, 72) or the surface of the applicator element.
Applicator element according to one of the preceding claims, characterized in that the liquid layer has a relatively low surface tension in the range of 20 to 45 mN/m, in particular in the range of 25 to 35 mN/m.
Applicator element according to one of the preceding claims, characterized in that the liquid layer has a relatively high surface tension in the range of 50 to 80 mN/m, in particular in the range of 55 to 70 mN/m.
Applicator element according to one of the preceding claims, characterized in that the air gap (L) has a gap width depending on the printing resolution (dpi).
Method for providing a layer of liquid ink, in particular for inking a latent image carrier of a device for electrographic printing or copying, the surface of the applicator element (26) being prepared such that it has a structure with a plurality of areas (78, 80, 86, 88), at which the detachment of droplets from an applied liquid layer is facilitated.
Method according to one of the preceding claims, characterized in that the structure of the surface of the applicator element (26) has a plurality of third areas (88) that are formed as microscopic elevations on the otherwise smooth surface.
Method according to one of the preceding claims, characterized in that the liquid ink and/or the liquid layer contains a nontoxic and/or nonflammable and/or non-odorous carrier liquid, preferably water.
Method according to one of the preceding claims, characterized in that the liquid film is supplied to the surface of the applicator element (26, 26a) via a feed roller (36).
Method according to one of the preceding claims, characterized in that a liquid film (38) is supplied to the feed roller (36) via a scoop roller (40), a portion of which is dipped into a supply of liquid ink.
Method according to one of the preceding claims, characterized in that a smooth liquid film is sprayed onto the feed roller.
Method according to one of the preceding claims, characterized in that the applicator element dips with a portion thereof into a bath containing the ink, and in that the dosage of the accepted amount of liquid takes place via an elastic roll doctor that acts on the surface of the applicator roller.
Method according to one of the preceding claims, characterized in that the liquid layer (48) is formed as a layer having a plurality of droplets.
Method according to one of the preceding claims, characterized in that the surface of the applicator element (26) is provided with a continuous liquid layer (72).
Method according to one of the preceding claims, characterized in that an alternating force field is present in the air gap (L), said force field acting on the liquid layer (48, 72) or on the surface of the applicator element.
Method according to one of the preceding claims, characterized in that the liquid layer has a relatively low surface tension in the range of 20 to 45 mN/m, in particular in the range of 25 to 35 mN/m.
Method according to one of the preceding claims, characterized in that the liquid layer has a relatively high surface tension in the range of 50 to 80 mN/m, in particular in the range of 55 to 70 mN/m.
Method according to one of the preceding claims, characterized in that the air gap (L) has a gap width depending on the printing resolution (dpi).
Dependencies are inferred from the claim text.