METHOD AND SYSTEM FOR APPLYING A PATTERN ON A MASK LAYER

Abstract

A method for applying a pattern on a mask layer includes obtaining an image file representing pixels with a first pixel size in a first direction parallel to an edge of the pixel, and a second pixel size in a second direction perpendicular to the first direction, where the first and second pixel size are the same or different, treating the mask layer such that a plurality of areas with altered physical properties are created in the mask layer, the plurality of areas corresponding to a plurality of pixels of the image file, where the treatment is done such that a first and/or a second area size of an area of said plurality of areas, seen in said first and/or said second direction, is smaller than the first and/or second pixel size, respectively.

Claims

1. A method for applying a pattern on a mask layer, said method comprising: obtaining an image file representing pixels with a first pixel size in a first direction parallel to an edge of the pixel, and a second pixel size in a second direction perpendicular to the first direction, wherein the first and second pixel size are the same or different; treating the mask layer such that a plurality of areas with altered physical properties are created in the mask layer, said plurality of areas corresponding to a plurality of pixels of the image file, wherein the treatment is done such that a first and/or a second area size of an area of said plurality of areas, seen in said first and/or said second direction, is smaller than the first and/or second pixel size, respectively; wherein the method is performed without manipulating the image file for obtaining a surface screen pattern on the mask.

2. The method of claim 1, wherein the treatment is done such that an area size of an area of said plurality of areas, seen in said first and said second direction, is smaller than the first and second pixel size, respectively.

3. A method for applying a pattern on a mask layer, said method comprising: obtaining an image file representing pixels with a first pixel size in a first direction parallel to an edge of the pixel, and a second pixel size in a second direction perpendicular to the first direction, wherein the first and second pixel size are the same or different; treating the mask layer such that a plurality of areas with altered physical properties are created in the mask layer, said plurality of areas comprising at least a first and second area corresponding to directly adjacent first and second pixels of the image file, wherein the treatment is done such that the first and second area do not overlap in the first direction and/or in the second direction.

4. The method according to claim 1, wherein the plurality of areas correspond to a plurality of holes or to a plurality of areas with a transparency to electromagnetic radiation which is different from the transparency of the untreated mask material.

5. The method according to claim 1, wherein the first and/or second area size is in the range of 20% to 99%, preferably in the range of 30% to 90%, more preferably in the range of 40% to 80%, of the first and/or second pixel size, respectively.

6. The method according to claim 1, where the step of treating the mask layer is done using a beam of a first electromagnetic radiation.

7. The method according to claim 6, wherein the beam has a first and second beam size in said first and second direction, wherein said first and/or second beam size is smaller than the first and/or second pixel size, respectively, said first and second beam size being the longest distance in an intensity profile, of a cross section of the beam in said first and second direction, respectively, between two points in the intensity profile where the intensity equals 50% of the maximum intensity in this cross section.

8. The method according to claim 7, wherein the first and/or second beam size is in the range of 20% to 95%, respectively.

9. The method according to claim 6, wherein the beam is chosen to have a wavelength, a first and second beam size, a beam power and an on-time, wherein said beam power and/or said first and/or second beam size and/or said on-time is set based on an analysis of the obtained image file.

10. The method according to claim 6, wherein a beam used for generating areas corresponding with pixels of a first region of the image file is different from a beam used for generating areas corresponding with pixels of a second region of the image file.

11. The method according to claim 6, wherein a beam, and in particular the first and/or second beam size and/or the beam power thereof, is chosen in function of a tonal value of pixels of a halftone region of the image file.

12. The method according to claim 6, wherein the cross section of the beam has a circular, elliptic, square, rectangular or polygonal shape, and/or wherein the intensity profile of the beam is Gaussian, trapezoidal or rectangular.

13. The method according to claim 6, wherein the mask layer initially is essentially in-transparent for first the electromagnetic radiation of the beam; and/or wherein the mask layer is undergoing a change in transparency due to ablation, and/or bleaching, and/or color change, and/or polarization change when exposed to the first electromagnetic radiation.

14. The method according to claim 1, wherein the step of treating the mask layer is controlled, such that, for an image region of the image included in the image file, the plurality of areas corresponding to the at least one image region form a pattern, wherein preferably said pattern is any one of the following: a regular or periodic pattern, a stochastic pattern or a combination thereof; wherein the image region corresponds to a halftone region or a solid region.

15. The method according to claim 14, wherein the step of treating the mask layer is controlled, such that, for an image region of the image included in the image file, the first and/or second area size and/or the distribution of the areas is the same or different in an area close to the center and an area close to the edge of the image region.

16. The method according to claim 1, wherein the step of treating the mask layer is controlled, such that, for an image region of the image included in the image file, the density of the areas is set in function of the size of the image region and/or the density of the areas increases or decreases from the center of the image region to the edge of the image region.

17-18. (canceled)

19. The method according to claim 1, wherein the obtained image file has not been manipulated by changing the image file resolution and/or has not been manipulated by removing pixels to generate said plurality of areas within the image file.

20. (canceled)

21. The method according to claim 1, wherein the mask layer is comprised in a printing plate precursor; wherein the printing plate precursor comprises one or more layers selected from the list consisting of a support layer, a photoactive layer, a protective layer, a barrier layer, a diffracting layer, a diffusing layer, an adhesive layer, or combinations thereof.

22. A method to form an imaged layer composition, said method comprising the steps: combining a mask layer and a substrate layer to form a layer composition, applying a pattern to the mask layer according to the method of claim 1, treating the layer composition such that the substrate layer undergoes a property change in a plurality of substrate areas corresponding with the plurality of areas created in the patterned mask layer, such that an imaged layer composition is formed.

23. The method according to claim 22, wherein the step of treating the layer composition is done with a second electromagnetic radiation.

24-43. (canceled)

44. A system for applying a pattern on a mask layer, said system comprising: a control module configured for obtaining an image file representing pixels with a first pixel size in a first direction parallel to an edge of the pixel, and a second pixel size in a second direction perpendicular to the first direction, wherein the first and second pixel size are the same or different; a treatment means configured for treating the mask layer such that a plurality of areas with altered physical properties are created in the mask layer, said plurality of areas corresponding to a plurality of pixels of the image file; wherein said control module is further configured to control the treatment such that a first and/or second area size of an area of said plurality of areas, as measured in said first and second direction, is smaller than the first and second pixel size, respectively; wherein the controlling is performed without manipulating the image file for obtaining a surface screen pattern on the mask.

45. A system for applying a pattern on a mask layer, said system comprising: a control module configured obtaining an image file representing pixels with a first pixel size in a first direction parallel to an edge of the pixel, and a second pixel size in a second direction perpendicular to the first direction, wherein the first and second pixel size are the same or different; a treatment means configured for treating the mask layer such that a plurality of areas with altered physical properties are created in the mask layer, said plurality of areas comprising at least a first and second area corresponding with directly adjacent first and second pixels of the image file; wherein said control module is further configured to control the treatment means such that the first and second area do not overlap in the first and/or second direction.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0056] The accompanying drawings are used to illustrate presently preferred non-limiting exemplary embodiments of methods and systems of the present invention. The above and other advantages of the features and objects of the invention will become more apparent and the invention will be better understood from the following detailed description when read in conjunction with the accompanying drawings, in which:

[0057] FIGS. 1A-1E illustrate schematically an embodiment of the prior art;

[0058] FIGS. 2A-2C illustrate an exemplary embodiment of a method according to the invention;

[0059] FIGS. 3A-3D illustrate four exemplary embodiments showing for each embodiment a plurality of pixels with its corresponding treated areas;

[0060] FIGS. 4A and 4B illustrate two examples of the prior art, the image file, the laser beam used and the exposed image;

[0061] FIG. 4C illustrates an example of the prior art which apply surface screening in the image file, wherein each figure shows respectively an image file, the applied surface pattern, the modified image file, the laser beam used and the exposed image on the mask layer;

[0062] FIGS. 5A and 5B illustrate two exemplary embodiments of the invention, wherein each figure shows respectively the used image file, the used laser beam, and the exposed image on the mask;

[0063] FIG. 6A is a top view of an exemplary embodiment of a mask;

[0064] FIG. 6B is a top view of an exemplary embodiment of a printing plate in an inked state;

[0065] FIG. 6C is a top view of a printed medium using the printing plate of FIG. 6B;

[0066] FIGS. 7A and 7B compare a printed sample printed using a relief plate made in accordance with the prior art example of FIG. 4A, and made in accordance with the exemplary embodiment of the invention of FIG. 5B, respectively.

DETAILED DESCRIPTION OF EMBODIMENTS

[0067] FIGS. 2A-2C and FIG. 3A illustrate an exemplary embodiment of a method according to the invention. In a first step illustrated in FIG. 2A and image file is obtained having an image file resolution corresponding to a pixel size p (see the detail shown in FIG. 3A). The illustrated image file has square-shaped pixels 4 such that the first and second pixel size seen in a first direction and in a second direction perpendicular on the first direction, are the same and are equal to p. The illustrated image file contains a substantially round image region 1 to be printed. The image file resolution corresponding with pixel size p may be e.g. 4000 dpi. Next a mask layer is treated with a beam of first electromagnetic radiation. The beam is adapted to generate a treated area A, here a hole 2. The generated hole 2 is illustrated in FIG. 2B and has an area size h which is smaller than the pixel size p, see also FIG. 3A. Using such a beam, a plurality of holes 5 are created in the mask layer, said plurality of areas corresponding to a plurality of pixels 4 of the image file. A top view of the mask layer is illustrated in FIG. 2C. FIG. 3A shows a detail with four pixels of FIG. 2C.

[0068] The beam, and in particular the beam size, is chosen such that an area size h of a hole 5 of the plurality of holes 5 is smaller than the pixel size p. The plurality of holes 5 comprises at least a first and second area A1, A2, here a first and second hole 5a, 5b corresponding to directly adjacent first and second pixels 4a, 4b of the image file, wherein the treatment by the beam is done such that the first and second hole 5a, 5b do not overlap. When referring to directly adjacent pixels, it is meant that the pixels have a common edge, i.e. either an edge in the first direction or an edge in the second direction. In other words, in the example of FIGS. 2A-2C and 3A, directly adjacent pixels have a common edge with a length which corresponds to the pixel size p.

[0069] FIGS. 3B-3D illustrate other possible pixel sizes and area sizes. In the embodiment of FIG. 3B, the pixels are square and have a pixel size p. The first and second area size h1, h2 are different. In the illustrated example the area is substantially elliptic with a first smallest area size h1 extending in a first direction, which is smaller than the pixel size p, and with a second larger area size h2 extending in a second direction perpendicular on the first direction, which is larger than the pixel size p (h1<p, h2>p). In that way a first plurality of areas A1 can be formed, said areas A1 overlapping in the second direction but not in the first direction, and a second plurality of areas A2 can be formed which overlap in the second direction but not in the first direction, wherein the second plurality does not overlap with the first plurality. In that way the surface screen pattern will look more or less as a line pattern.

[0070] In another non-illustrated example the area is substantially elliptic with a first smallest area size h1 extending in a first direction, which is smaller than the pixel size p, and with a second larger area size h2 extending in a second direction perpendicular on the first direction, which is also smaller than the pixel size p (h1<p, h2<p). In that way a plurality of areas A1, A2 can be formed which do not overlap in the first and second direction.

[0071] In the embodiment of FIG. 3C, the pixels are rectangular and have a first pixel size p1 in a first direction and a second pixel size p2 in a second direction perpendicular to the first direction. Also, the first and second areas size h1, h2 are different. In the illustrated example the area is substantially elliptic with a first smallest area size h1 extending in the first direction, which is smaller than the first pixel size p1, and with a second larger area size h2 extending in the second direction, which is smaller than the second pixel size p2 (h1<p1, h2<p2). In that way a plurality of areas A1, A2 can be formed which do not overlap in the first and second direction.

[0072] In the embodiment of FIG. 3D, the pixels are also rectangular and have a first pixel size p1 in a first direction and a second pixel size p2 in a second direction perpendicular to the first direction. The first and second areas size h1, h2 may be the same or different. In the illustrated example the area is substantially circular with a first area size h1 extending in the first direction, which is larger than the first pixel size p1, and with a second area size h2 extending in the second direction, which is smaller than the second pixel size p (h1>p1, h2<p2). In that way a first plurality of areas A1 can be formed which overlap in the first direction but not in the second direction, and a second plurality of areas A2 can be formed which overlap in the first direction but not in the second direction, wherein the second plurality does not overlap with the first plurality. In that way the surface screen pattern will look more or less as a line pattern.

[0073] FIGS. 4A and 4B illustrate for two examples of the prior art, the image file (on the left), the laser beam used (bottom image) and the exposed image (on the right). No surface screening is applied. In the exposed image adjacent areas overlap as the beam size used is larger than the pixel size. FIG. 4C illustrates another example of the prior art which applies surface screening in the image file, wherein the figure shows respectively an image file (top left), the applied surface pattern (bottom left), the modified image file (top middle), the laser beam used (bottom right) and the exposed image on the mask layer (top right). In the exposed image of FIG. 4C, adjacent areas corresponding with directly adjacent pixels would overlap as the beam size used is larger than the pixel size, but because surface screening is performed in the image file, there are no adjacent areas corresponding with directly adjacent pixels.

[0074] FIGS. 5A and 5B illustrate two exemplary embodiments of the invention, wherein each figure shows respectively the used image file (top left), the used laser beam (bottom), and the exposed image on the mask (top right). The pixels have a square shape with a pixel size which is the same in a first and second direction, as described above in connection with FIGS. 2A-2C and FIG. 3A. The used beam is circular and has a beam size which is smaller than the pixel size, and no surface screening is done in the image file.

[0075] FIG. 6A is a top view of an exemplary embodiment of a mask with a plurality of mask regions 6 corresponding with a plurality of halftone image regions. Each mask region 6 comprises a plurality of holes 5. In the example, the mask region comprises adjacent holes 5a, 5b corresponding with directly adjacent pixels. FIG. 6B is a top view of an exemplary embodiment of a printing plate made using the mask of FIG. 6A, in an inked state. FIG. 6C is a top view of a printed medium using the printing plate of FIG. 6B.

[0076] FIGS. 7A and 7B compare a printed sample printed using a relief plate made in accordance with the prior art example of FIG. 4A, and made in accordance with the exemplary embodiment of the invention of FIG. 5B, respectively. It can be seen that the result obtained with the embodiment of the invention is significantly better compared to the result obtained according to the prior art example.

EXAMPLES

[0077] In table 1 three examples of the prior art (Ref. 1 to Ref. 3) are compared with two examples (Ex. 1 to Ex. 2) of the present invention.

[0078] Different methods and beam sizes were applied to a digital printing plate precursor comprising an integrated mask layer, which may be ablated by an IR Laser beam. Table 1 contains the specific dimensions, beam shapes and intensity profiles, as well as the results obtained upon printing (solid ink density).

TABLE-US-00001 TABLE 1 Relative Number Rel- Relative Laser of ative File Sur- size of Beam tonal file size face Size hole Image Surface Dia- values size after screen- of in the File Pattern Beam meter @150 lpi in % sur- ing hole mask reso- Pixel Reso- Dia- (% of classic (typ- face comp- in (% of Solid lution size lution meter Beam Intensity pixel screen ical screen- utation mask pixel Ink Sample (dpi) (μm) (lpi) (μm) Shape profile size) ruling file) ing time (μm) size) density Ref. 1 2540 10 none 11 Round Gauss 110 286 ~120 equal none 12.5 125 low Fig. 4A Ref. 2 4000 6.35 none 7 Round Gauss 110 711 ~220 equal none 8 125 low Fig. 4B Ref. 3 4000 6.35 1414 7 Round Gauss 110 89 ~250 larger extra 12.7 200 high Fig. 4C Ex. 1 2000 12.7 2000 6 Round Gauss 47 177 ~100 equal none 6 47 high Fig. 5A Ex. 2 2540 10 2540 6 Round Gauss 60 286 ~120 equal none 6 60 high Fig. 5B

[0079] The image file resolution (dpi) is the number of pixels per inch, counted in one dimension and expressed in dpi (dots per inch) or ppi (pixels per inch), in the image file. For the examples of the table the pixels are square. The pixel size, in micron and in that dimension, is the inverse of the resolution in dpi, multiplied by 25400.

[0080] The beam diameter (micron) is the longest measured distance in the intensity profile, of any cross section of the beam, between two points in the intensity profile where the intensity equals 50% of the maximum intensity in this section. The intensity profile is the intensity profile of light as generated by a single imaging pixel.

[0081] The intensity profile is the spatial distribution of the light intensity (W/mm2) of the laser beam. Typical profiles can be merely Gaussian, merely rectangular (top hat) or merely trapezoidal. The intensity profile is the intensity profile of light as generated by a single imaging pixel.

[0082] The beam shape is the 2-D shape of a cross section of the intensity profile at a specific intensity value. Typical beam shapes are elliptical or round, or are polygonal (square, rectangular, triangular, hexagonal, . . . ). The intensity profile is the intensity profile of light as generated by a single imaging pixel.

[0083] The number of tonal values in a classic screen with additional surface screening is the number of surface pattern elements in a full tone classic screen element. It is equal to the square of the ratio between the surface screen lpi and the classic screen lpi.

[0084] The size of the hole in the mask in micron is the size of the hole in the mask, created by the intensity profile of the exposing light, generated by a single imaging pixel. It is analyzed with a transmitted light microscope and uses the transmitted light intensity profile. It is measured as the longest distance in the transmitted intensity profile between two points in the transmitted intensity profile where the transmitted intensity equals 50% of the maximum transmitted intensity.

[0085] The solid ink density is measured on a printed sample of a solid area, as the reflected density using a digital densitometer.

[0086] The results for examples 1 and 2 in table 1 clearly show that a high ink density was obtained in a shorter time and without manipulation of the image file.

[0087] The table above shows that the surface pattern screening resolution that can be obtained with the embodiments of FIGS. 5A and 5B is higher than the surface pattern screening resolution that can be obtained with embodiments of the prior art (FIGS. 4A-4C) whilst the file size can remain small.

[0088] Whilst the principles of the invention have been set out above in connection with specific embodiments, it is to be understood that this description is merely made by way of example and not as a limitation of the scope of protection which is determined by the appended claims.