US 6,578,478 B2Granted

Electrostatic arrangement for rotogravure and flexographic printing unit

AssigneeSpengler Electronic AG

InventorAlfred Doppler

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Abstract

The electrostatic printing aid for gravure and flexographic printing machines can be operated with a voltage electrode whose dimensions have been reduced significantly, the print quality being kept at a high level. The voltage electrode, connected to a high voltage source, can be constructed with a bar-like or arc-like shape and to be non-contacting, or as a slip ring or as an electrically conductive brush. The voltage electrode is preferably arranged at one end of the three-layer impression roller of a gravure printing unit or the three-layer printing plate cylinder of a flexographic printing unit. The particular advantages of the arrangement reside in the significantly improved ease of servicing and the saving in costs, as early as at the time of purchase, in particular in the event of retrofitting printing machines already in operation.

Claims28

Dependent claims

An electrostatic arrangement for a gravure printing unit for polarizing the ink molecules used in the gravure printing unit, comprising:

a multi-layer impression roller, a voltage electrode positioned relative to said impression roller such that an air gap is formed therebetween, and a printing plate cylinder positioned close to said impression roller such that a web of a printing material is feedable between said impression roller and said printing plate cylinder,
said voltage electrode being an inductor electrode and having a plurality of emission needles which are spaced apart from one another, said plurality of emission needles each having a tip and, when a DC voltage is applied to said voltage electrode, current flows from said tips of said plurality of emission needles, through said air gap, and into said impression roller, and
said plate cylinder having dimples to carry the ink molecules, wherein
said multi-layer impression roller has an impression roller core, an outermost semiconductor layer, a highly conductive layer underneath said semiconductor layer and an insulating layer underneath said highly conductive layer and adjacent to said impression roller core,
said voltage electrode being positioned such that said air gap is located between said voltage electrode and said semiconductor layer of said multi-layer impression roller;
and
said multi-layer impression roller has a longitudinal length and said voltage electrode extends longitudinally and axially having a length of not greater than about 50% of said length of said multi-layer impression roller.

4 more elements

An electrostatic arrangement for a flexographic printing unit for polarizing the ink molecules used in the flexographic printing unit, comprising:

a multi-layer printing plate cylinder, a voltage electrode positioned relative to said printing plate cylinder such that an air gap is formed therebetween, a substrate transfer roll and a back-pressure cylinder such that a web of a printing material is feedable between said printing plate cylinder and said back-pressure cylinder,
said voltage electrode being a inductor electrode and having a plurality of emission needles spaced apart from one another, said plurality of emission needles each having a tip and, when a DC voltage is applied to said voltage electrode, current flows from said tips of said plurality of emission needles, through said air gap, and into said printing plate cylinder, and
said substrate transfer roll and said printing plate cylinder carrying the ink molecules, wherein
said printing plate cylinder has a cylinder core, an outermost semiconductor layer which is a stereotype plate, a highly conductive layer located underneath said semiconductor layer and an insulating layer located underneath said highly conductive layer and adjacent to said cylinder core,
said voltage electrode being positioned such that said air gap is located between said voltage electrode and said stereotype plate;
and
said printing plate cylinder has a longitudinal length and said voltage electrode extends longitudinally and axially having a length of not greater than about 50% of said length of said printing plate cylinder.

4 more elements

Dependencies are inferred from the claim text.