A system for exposing a heat and/or light sensitive printing plate precursor including a coating on a support includes a platesetter including a laser head for generating a laser beam to create an image, and the platesetter further includes an electrostatic generator capable of electrostatically charging the surface of the coating.

Provided is a photosensitive resin composition, including: a polymer compound which has a polycyclic structure and a sulfonamide group in a main chain thereof; and an infrared absorbent, wherein the polycyclic structure has at least one structure selected from the group consisting of a fused cyclic hydrocarbon structure and a fused polycyclic aromatic structure.

Provided is a photosensitive resin composition, including: a polymer compound which has a polycyclic structure and a sulfonamide group in a main chain thereof; and an infrared absorbent, wherein the polycyclic structure has at least one structure selected from the group consisting of a fused cyclic hydrocarbon structure and a fused polycyclic aromatic structure.

A method according for preparing a lithographic printing plate containing a lithographic image consisting of printing areas and non-printing areas includes the steps of jetting and curing droplets of a first curable fluid on a hydrophilic support thereby forming a printing area of the lithographic image; and jetting and curing droplets of a second curable fluid in a non-printing area of the lithographic image thereby forming a hydrophilic protective layer on the hydrophilic support.

A halftone raster image suitable for rendering a continuous-tone image includes a plurality of spiral dots. The spiral dots include image pixels arranged as a first arc or as a plurality of arcs which together represent a first spiral, and non-image pixels arranged as a second arc or as a plurality of arcs which together represent a second spiral. The spiral dots enable a controlled spreading of the ink within the dot, resulting in a higher image quality, ink saving, and faster drying.

A halftone raster image suitable for rendering a continuous-tone image includes a plurality of spiral dots. The spiral dots include image pixels arranged as a first arc or as a plurality of arcs which together represent a first spiral, and non-image pixels arranged as a second arc or as a plurality of arcs which together represent a second spiral. The spiral dots enable a controlled spreading of the ink within the dot, resulting in a higher image quality, ink saving, and faster drying.

A positive-working lithographic printing plate precursor is disclosed which comprises on a support having a hydrophilic surface or which is provided with a hydrophilic layer a heat and/or light-sensitive coating including an infrared absorbing agent, said heat and/or light-sensitive coating comprising a first layer comprising a binder including a monomeric unit including a sulfonamide group; characterized in that the binder further comprises a monomeric unit including a phosphonic acid group or a salt thereof, and that the monomeric unit comprising the phosphonic acid group is present in an amount comprised between 2 mol % and 15 mol %.

A method of lithographic plate making is disclosed wherein a plate precursor is exposed to laser radiation in the wavelength range from 350 to 450 nm, said plate precursor comprising a hydrophilic support and a photopolymerizable or photocrosslinkable image recording layer, and then processed on-press by supplying fountain and ink. The exposure produces a visible image having a 1976 CIELAB color distance AF between exposed and non-exposed areas of at least 2.5.

A source of actinic radiation for curing printing plates. The source includes a base with a heat sink and has a length greater than its width. One or more circuit boards mounted on the base provide a plurality of light emitting diodes (LEDs) distributed over the length of the base. A transparent or translucent cover together with the base defines an enclosure for the plurality of LEDs. The source provides the radiation at an emission angle greater than the emission angles of a single LED in a plane perpendicular to the axis of the base, in a plane containing the axis of the base or parallel to the axis of the base and perpendicular to the target illumination plane, or a combination thereof. The source may be configured to replace a fluorescent bulb. Methods and systems for bank exposure of printing plates using such sources are also described.

A negative-working infrared radiation-sensitive lithographic printing plate precursor can be imaged and developed on-press to provide a lithographic printing plate. Such precursor has an initiator composition that contains compound A of Structure (I) and one or more compounds collectively as compound B of Structure (II) or Structure (III):

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wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are independently alkyl or alkoxy groups each having 2 to 9 carbon atoms; at least one of R.sub.3 and R.sub.4 is different from R.sub.1 or R.sub.2; the difference of total number of carbon atoms in R.sub.1 and R.sub.2 and the total number of carbon atoms in R.sub.3 and R.sub.4 is 0 to 4; the difference of total number of carbon atoms in R.sub.1 and R.sub.2 and the total number of carbon atoms in R.sub.5 and R.sub.6 is 0 to 4; and X.sub.1, X.sub.2 and X.sub.3 are the same or different anions.