Method and system for applying a pattern on a mask layer

Abstract

A method for applying a pattern on a mask layer, the method comprising: obtaining an image file representing a pixel, the pixel having a first pixel size (p; p1) in a first direction parallel to the edge of the pixel and a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first and second pixel sizes are the same (p) or different (p1, p2); processing the mask layer so as to produce a plurality of areas with changed physical properties on the mask layer, the plurality of areas (A) corresponding to a plurality of pixels of the image file, wherein the processing is performed so that the first and / or second area sizes (h; h1, h2) of the areas in the plurality of areas seen in the first and / or second directions are respectively smaller than the first and / or second pixel sizes (p; p1, p2).

Description

Technical Field

[0001] The field of the invention relates to methods and systems for applying patterns on mask layers, in particular mask layers for making relief precursors and more particularly flexographic printing plate precursors. The invention also relates to the masks obtained and to the relief precursors obtained. Background Art

[0002] Flexographic printing or letterpress printing is a technique commonly used for mass printing. A flexographic printing plate or letterpress printing plate is a raised plate in which image elements protrude above non-image elements to produce an image on a recording medium such as paper, paperboard, film, foil, laminate, etc. In addition, cylindrical printing plates or sleeves may be used.

[0003] There are various methods for making flexographic printing plate precursors. According to conventional methods, flexographic printing plate precursors are made of a multilayer substrate comprising a backing layer and one or more photocurable layers. These photocurable layers are imaged to obtain relief plates by transferring the image information through exposure to electromagnetic radiation or by direct and selective exposure to light (e.g., by scanning plates) via a mask layer containing the image information.

[0004] In flexographic printing, ink is transferred from a flexible printing plate to the print medium. More specifically, the ink is transferred to the raised areas of the plate, but not to the non-raised areas. During the printing process, the ink on the raised areas is transferred to the print medium. Grayscale images are usually created using halftones, for example using a screening pattern. Grayscale refers to the amount of a particular color that is copied for a plate print. For example, a printing plate can include different areas of halftone dots so that printing occurs with different densities in these areas. In order to increase the amount of ink transferred and to increase the so-called ink density on the substrate, an additional very fine structure is applied to the surface of the printed areas (i.e. the raised areas). This surface screening is usually obtained by adding a fine structure to the image file, which is then transferred to the corresponding mask used for exposure.

[0005] Figure 1A An embodiment of a prior art method for manufacturing a raised plate is shown in FIG. 1E . Figure 1AThe content of an image file is shown, the image file having an image file resolution corresponding to a pixel size p (e.g., 6.35 microns). The image file shown has square pixels 4 and contains a substantially circular image area 1 to be printed. The image file resolution may be, for example, 4000 dpi (=25400*1 / p (in microns)). Next, the image file is manipulated using the surface screen pattern shown in FIG. 1B . Applying the surface screen pattern in the image area 1 produces the modified image file shown in FIG. 1C . As shown in FIG. 1C , the generated image area 1 'contains fewer pixels 4' to be printed, and the pixels 4' to be printed are spaced d apart from each other.

[0006] Based on the modified image file of FIG. 1C , a mask is prepared. More specifically, for each pixel 4 ′ to be printed, a hole or transparent area 5 is arranged in the mask. This can be done using a beam of electromagnetic radiation. Figure 1D As shown, such a beam will produce a hole 2, here a circular hole 2, which is slightly larger than the size of the pixel 4'. The resulting image on the mask is shown in Figure 1E. The screen pattern resolution is defined as the number of screen elements per inch (corresponding to the pixels 4' of the holes 5 in the mask) calculated along the line that minimizes the distance between the nearest screen elements, which for the embodiment of Figure 1E can be, for example, 1414lpi (=1 / (2*√2)*4000). This is shown in Figure 1C, which shows the value of the nearest distance as d (in microns), where the screen pattern resolution in lpi is equal to the inverse of d (in microns) multiplied by 25400.

[0007] Therefore, according to Figure 1A 1E , the surface screening is calculated by altering the original image file (eg tiff file) using software (usually raster image processing techniques), where a file with a larger size is usually generated due to the manipulation.

[0008] One embodiment of this method is disclosed in WO 2017 / 203034A1. WO 2017 / 203034A1 discloses a method for manufacturing a flexible printed plate or a mask for producing a flexible printed plate. The method comprises providing a basic pattern (usually a high-resolution basic pattern, see Figure 1A1E), each dot comprising the smallest exposed discrete element represented on the screen. Preferably, each dot in the base pattern comprises an isolated pixel comprising an exposed pixel surrounded by eight unexposed pixels. The plate or mask is created by selectively modulating the size of the physical dots corresponding to the screen dots on the plate or mask in at least a portion of the plate or mask corresponding to the non-solid tonal areas of the plate, such that each group of four adjacent physical dots in the base pattern has an unexposed area located centrally between them. This is preferably accomplished by imaging the mask with a laser beam, wherein the power of the laser beam is enhanced relative to the laser beam for non-isolated pixels for imaging each isolated pixel. It is further mentioned that any tunable system can be used to produce the desired ink transfer characteristics to selectively modulate the size of the physical dots corresponding to the screen dots on the plate or mask, such that each group of four adjacent physical dots in the base pattern has an unexposed area located centrally between them. Summary of the invention

[0009] It is an object of embodiments of the present invention to provide a method and system for faster application of a pattern on a mask layer that reduces or eliminates the need to manipulate an image file and allows for improved printing of solid and halftone areas of an image file.

[0010] According to a first aspect of the present invention, a method for applying a pattern on a mask layer is provided. The method comprises the steps of obtaining an image file representing a pixel having a first pixel size in a first direction and a second pixel size in a second direction, wherein the first pixel size and the second pixel size are the same or different; and processing the mask layer so that a plurality of regions with changed physical properties are generated in the mask layer, the plurality of regions corresponding to a plurality of pixels of the image file. The processing is performed so that the first region size and / or the second region size of a region in the plurality of regions measured in the first direction and the second direction are respectively smaller than the first pixel size and the second pixel size. Preferably, the region size is measured as the longest distance between two points in a transmission intensity distribution, where the transmission intensity is equal to 50% of the maximum transmission intensity.

[0011] Compared to the prior art solutions, according to embodiments of the present invention, instead of processing the mask layer such that the processing area corresponding to a pixel is larger than the pixel size (see the discussion in the background section above), the processing area has a first and / or second area size that is smaller than the first and / or second pixel size, respectively. Figure 1D). In this way, a surface screen pattern can be created on the mask without the need to manipulate the image file. It should be noted that it is still possible to manipulate the image file due to other sources, but this is not necessary to obtain the surface screen pattern on the mask. Since the image file does not have to be manipulated or is manipulated only to a limited extent, the image file to be used will be smaller compared to the modified prior art image file, resulting in faster data transfer. In addition, by making the first and / or second area size of the processing area smaller than the first and / or second pixel size, respectively, finer gradations of the surface screening pattern become possible.

[0012] In WO 2017 / 203034A, in contrast to the first aspect, a screen with a high resolution defined by a basic pattern is used to manipulate the image file.

[0013] It should be noted that embodiments of the present invention may also be useful when surface screening is not required. In fact, by having a smaller processing area than the prior art, processing may be faster because less material needs to be processed. In addition, processing will require less electricity.

[0014] Preferably, the processing is performed so that the area size of the area of ​​the plurality of areas seen in the first direction and / or the second direction is smaller than the first pixel size and the second pixel size, respectively. The first direction is preferably perpendicular to the second direction. Preferably, the first direction extends parallel to a first side of the pixel, and the second direction extends parallel to a second side of the pixel that is perpendicular to the first side. More preferably, the surface area of ​​the area of ​​the plurality of areas, as measured in the top surface of the mask layer, is smaller than the surface area of ​​the pixel.

[0015] According to a second aspect of the present invention, there is provided a method for applying a pattern on a mask layer. The method comprises the steps of obtaining an image file representing a pixel having a first pixel size in a first direction and a second pixel size in a second direction, wherein the first pixel size and the second pixel size are the same or different; and processing the mask layer so as to produce a plurality of regions of changed physical properties in the mask layer. The plurality of regions comprises at least a first and a second region corresponding to directly adjacent first and second pixels of the image file. The processing is performed so that the first and the second regions do not overlap in the first direction and / or the second direction.

[0016] In WO 2017 / 203034A, in contrast to the second aspect, the screen uses isolated pixels and there are no directly adjacent pixels having a corresponding processing area (ie, exposed area / physical point) of the size defined above.

[0017] The expression "directly adjacent first and second pixels" means that the distance between the first and second pixels is equal to the first pixel size in the first direction or the second pixel size in the second direction. The technical advantages of the first aspect described above are also applicable to the second aspect. Since the adjacent areas corresponding to the adjacent pixels do not overlap in the first and / or second areas, a surface screen pattern can be achieved on the mask without manipulating the image file. It should be noted that since the first area and the second area do not overlap in at least one of the first direction and the second direction, there is unprocessed mask material between the first area and the second area. Therefore, a surface screen pattern can be obtained.

[0018] Preferably, the processing is performed so that the first area and the second area do not overlap in the first direction and the second direction, and more preferably so that they do not overlap in any direction. The first direction is preferably perpendicular to the second direction. Preferably, the first direction extends parallel to a first side of the pixel, and the second direction extends parallel to a second side of the pixel that is perpendicular to the first side.

[0019] According to a preferred embodiment, the plurality of treated areas corresponds to a plurality of holes or a plurality of areas having a transparency different from the transparency of the untreated mask material. In other words, the treatment of the mask layer may consist of removing the mask layer material to produce holes, or may consist of a treatment of the mask layer that increases the transparency of the mask layer in a plurality of areas. Such treatment may be, for example, a discoloration or bleaching of a dye, a color change, a refractive index change, a polarization change, or a combination thereof.

[0020] According to a preferred embodiment, the first region size and / or the second region size is in the range of 20% to 99%, more preferably in the range of 30% to 90%, even more preferably in the range of 40% to 80% of the first pixel size and / or the second pixel size, respectively. Such first and / or second region sizes will allow the generation of suitable surface pattern screens without the need to manipulate image files.

[0021] According to a preferred embodiment, the step of treating the mask layer is performed using a beam of a first electromagnetic radiation.The wavelength of the first electromagnetic radiation may be in the range of 200nm to 2000nm, preferably in the range of 200nm to 400nm or 800nm ​​to 1500nm.

[0022] Preferably, the light beam has a first and / or second beam size measured in the first and second direction, which first and / or second beam size is smaller than the first and / or second pixel size, respectively. Preferably, the first and second beam sizes are measured as the longest distance of the intensity distribution between two points in the intensity distribution of the cross section of the light beam in said first and second directions, respectively, where the intensity is equal to 50% of the maximum intensity in the cross section. Such a first and / or second beam size will allow to obtain a first and / or second area size that is smaller than the first and / or second pixel size. For example, the first beam size and / or the second beam size is in the range of 20% to 95%, preferably in the range of 40% to 80%, of the first pixel size and / or the second pixel size. It should be noted that the first and second beam sizes are not the only parameters of the light beam that will affect the first and second area sizes. Furthermore, the wavelength of the light beam, the beam power and the duration of the light beam may affect the first and second area sizes. However, in general, the first and second beam sizes will be the main parameters affecting the first and second area sizes.

[0023] According to an exemplary embodiment, the light beam is selected to have a wavelength, a first and a second beam size, a beam power, and a duration, wherein the wavelength and / or the beam power and / or the first and / or the second beam size and / or the duration are set based on an analysis of the obtained image file. For example, the first and / or the second beam size may be adjusted based on information in the image file. For example, when it is necessary to print a grayscale image area, i.e., a halftone area, the first and / or the second beam size may be adjusted based on the grayscale value (also referred to as the tone value) of the image area.

[0024] In an exemplary embodiment, the light beams used to generate an area of ​​pixels corresponding to a first area of ​​the image file may be different from the light beams used to generate an area of ​​pixels corresponding to a second area of ​​the image file. For example, the first area may be a grayscale area having a first grayscale value, and the second area may be a solid area. In such an embodiment, the light beam group for the first area may have a smaller first and / or second light beam size than the light beam group for the second area. It should be noted that the first and / or second light beam size for the solid area and / or certain grayscale areas may also be equal to or greater than the first and / or second pixel size, respectively.

[0025] In a further developed embodiment, the light beam and in particular its first and / or second beam size and / or beam power can be selected depending on the tonal value of the pixels of the halftone area of ​​the image document. Preferably, the light beam is selected such that a smaller first and / or second area size is produced for lower tonal values ​​than for higher tonal values. In the context of the present invention, the term "greyscale area" is used as a synonym for the term "halftone area". Similarly, the term "tone value" is used as a synonym for the term "greyscale value".

[0026] The cross-section of the light beam may have a circular, elliptical, square, rectangular or polygonal shape. When the light beam size is circular or square, the first and second light beam sizes are the same. When the light beam shape is elliptical or rectangular, the first and second light beam sizes are different. In addition, the intensity distribution of the light beam may be Gaussian, trapezoidal or rectangular. Preferably, the light beam is arranged so that the center of the light beam is located near the center of the corresponding pixel or at the center of the corresponding pixel.

[0027] In a further developed embodiment, the shape of the light beam and / or the intensity distribution of the light beam may also be varied depending on the content of the image file.

[0028] According to an exemplary embodiment, the mask layer is initially substantially opaque to the first electromagnetic radiation of the light beam. Preferably, the mask layer absorbs more than 80% of the first electromagnetic radiation of the light beam. Preferably, when exposed to the first electromagnetic radiation, the mask layer undergoes a change in transparency due to ablation, bleaching, color change and / or polarization change. In a most preferred embodiment, the mask layer can be ablated by the first electromagnetic radiation, thereby generating holes in the mask layer. In the latter embodiment, the treated areas correspond to the holes.

[0029] In a further developed embodiment, the step of processing the mask layer can be controlled so that for an image area of ​​an image contained in an image file, a plurality of areas corresponding to at least one image area form a pattern. Preferably, the pattern is any of the following: a regular or periodic pattern, a random pattern. For example, the image area can be a halftone area, and the pattern can be a checkered pattern, a line pattern (wherein the lines are formed by non-overlapping adjacent processing areas), etc. In addition, the pattern can be selected depending on the type of image area. For example, the pattern of the halftone area may be different compared to the pattern of the solid area. It should be noted that it is also possible to manipulate the image file instead of controlling the processing of the mask layer. In other words, the pattern can be introduced in hardware and / or software.

[0030] It should be noted that when the mask area (e.g. corresponding to the halftone area) has a processing area with a first and / or second area size that is smaller than the first and / or second pixel size, respectively, a surface screening effect can be obtained without removing pixels. However, in addition to using a smaller first and / or second pixel size, pixels can also be "removed" to reduce the density of the processing area in the mask area. This can be done in software or by appropriately controlling the process, for example by turning the laser beam on and off according to the desired pattern that one wishes to achieve.

[0031] Additionally or alternatively, the step of processing the mask layer and / or manipulating the image file is controlled so that for an image area of ​​an image contained in the image file, the first area size and / or the second area size and / or the distribution of areas are the same or different for an area near the center of the image area and an area near the edge of the image area. For example, the first and / or second area size at the center may be smaller than the first and / or second pixel size, respectively, while the area size near the edge of the image area may be equal to or larger than the first and / or second pixel size. In this way, it becomes possible to create a closed edge of the image area. The size may be changed stepwise or continuously. This may be advantageous in keeping the ink on a convex area corresponding to the image area.

[0032] Additionally or alternatively, the step of processing the mask layer may be controlled and / or the image file may be manipulated such that:

[0033] - for an image region of an image contained in the image file, setting the density of the region according to the surface area of ​​the image region; and / or

[0034] - For an image region of an image contained in an image file, the density of the region increases or decreases from the center of the image region to the edge of the image region.

[0035] In other words, the surface pattern resolution may vary depending on the surface area of ​​the image region. For example, for image regions with relatively high tonal values, the density of the region may be higher than for image regions with relatively low tonal values.

[0036] In the above-described embodiments, the image area may correspond to a halftone area or a solid area.

[0037] Preferably, the pixels of the image file are square or rectangular. If the pixels are square, the first pixel size is equal to the second pixel size. If the pixels are rectangular, the first pixel size may correspond to the smallest of the width and length of the rectangular pixel, and the second pixel size may correspond to the largest of the width and length, and vice versa. Preferably, the first and second pixel sizes are in the range of 80 μm to 1 μm, preferably 25 μm to 2 μm, and more preferably 25 μm to 5 μm. The image file resolution is the number of pixels per inch calculated along the line that minimizes the distance between the nearest pixels. Therefore, when the pixel is a rectangle with a first pixel size and a second pixel size larger than the first pixel size, the image file resolution is calculated using the first pixel size. In other words, preferably, the image file resolution is in the range of 300 dpi to 20,000 dpi, preferably 1,000 dpi to 10,000 dpi, and more preferably 1,000 dpi to 5,500 dpi.

[0038] The mask layer may be included in the printing plate precursor. More specifically, the mask layer may be provided as an outer layer of the printing plate precursor, but the mask layer may also be provided as an intermediate layer within the printing plate precursor. The printing plate precursor may comprise one or more layers, preferably one or more of the following layers: a support layer, a photosensitive layer, a protective layer, a barrier layer, a diffractive layer, a diffusing layer, an adhesive layer or a combination thereof.

[0039] According to another aspect of the present invention, there is provided a method of forming an imaged layer composition. The method comprises the steps of combining a mask layer and a substrate layer to form a layer composition, and applying a pattern to the mask layer according to any of the embodiments of the methods disclosed above. The method comprises the further step of treating the layer composition so that the substrate layer undergoes a property change in a plurality of substrate regions corresponding to the plurality of regions produced in the patterned mask layer, thereby forming an imaged layer composition.

[0040] The step of treating the layer composition may be performed with a second electromagnetic radiation. The wavelength of the second electromagnetic radiation may be in the range of 200 nm to 2000 nm, preferably in the range of 200 nm to 400 nm.

[0041] The method further comprises at least one step of treating the layer composition to exploit the property change to obtain a further treated layer composition.For example, untreated portions of the substrate layer may be removed to produce a relief.

[0042] The step of applying a pattern to the mask layer may be performed after or before the step of combining the mask layer and the substrate layer. In other words, the mask layer may be first patterned before attaching it to the substrate layer, or it may be patterned while being attached to the substrate layer. The combination of the mask layer and the substrate layer may include attaching the mask layer to the substrate layer or using the mask layer and the substrate layer as an integral layer of the substrate.

[0043] The substrate layer may include a support layer, a photosensitive layer, a protective layer, an adhesive layer, a barrier layer, a sliding layer, a roughening layer, a layer that changes the polarization of an electromagnetic wave, or a combination thereof.

[0044] The property change caused by the treatment of the layer composition can be achieved by curing, solubility change, color change, refractive index change, transmission change, polarization change, or a combination thereof. The change in solubility can be achieved by polymerization, crosslinking, depolymerization, scission of polymer chains, scission of protective groups, or a combination thereof. Preferably, the change in solubility is achieved by polymerization and / or crosslinking, most preferably by free radical polymerization and / or crosslinking.

[0045] Using this method, the resulting imaged layer composition can form a relief precursor. For example, the treated areas of the substrate layer can correspond to the raised areas of the relief precursor. More particularly, the further treated layer composition can be a printing plate, such as an offset printing plate, a flexographic printing plate, a letterpress printing plate, a tampon printing plate or a gravure printing plate.

[0046] According to another aspect of the present invention, there is provided a mask having a mask layer having a pattern applied by a method according to any one of the embodiments disclosed above.

[0047] The present invention also relates to a combination or assembly of a mask and a computer storage medium. The computer-readable storage medium stores an image file representing a pixel having a first pixel size in a first direction and a second pixel size in a second direction, wherein the first pixel size and the second pixel size are the same or different. The mask includes a mask layer having a plurality of regions with changed physical properties. The plurality of regions correspond to a plurality of pixels of the image file. The first region size and / or the second region size of the regions in the plurality of regions measured in the first direction and / or the second direction are respectively smaller than the first pixel size and / or the second pixel size. The first region size and the second region size can be measured as described above. Additionally or alternatively, the plurality of regions include at least a first and a second region corresponding to adjacent first and second pixels of the image file, wherein the first and the second regions do not overlap in the first and / or the second direction.

[0048] The above-described technical advantages of the method apply mutatis mutandis to a combination or assembly of a mask and a computer-readable storage medium.

[0049] The present invention also relates to a relief precursor comprising an imaged layer composition obtained according to any one of the embodiments of the method for forming an imaged layer composition disclosed above.

[0050] According to another aspect of the present invention, there is provided an assembly or combination of a relief precursor and a computer-readable storage medium, the computer-readable storage medium storing an image file representing a pixel having a first pixel size in a first direction and a second pixel size in a second direction, wherein the first pixel size and the second pixel size are the same or different. The relief precursor comprises a substrate layer having a plurality of convex areas, the plurality of convex areas corresponding to a plurality of pixels of the image file. The first convex area size and / or the second convex area size of the convex areas in the plurality of convex areas measured in the first direction and / or the second direction are respectively smaller than the first pixel size and / or the second pixel size. The first convex area size and the second convex area size can be measured at the top surface of the convex area. Additionally or alternatively, the plurality of convex areas at least comprise first and second areas corresponding to directly adjacent first and second pixels of the image file. The first and second convex areas do not overlap in the first and / or second directions.

[0051] Furthermore, the invention relates to the use of such a relief precursor for printing an image contained in an image file representing pixels having a first pixel size in a first direction and a second pixel size in a second direction, wherein the first pixel size and the second pixel size are the same or different.

[0052] According to yet another aspect of the present invention, a system for applying a pattern on a mask layer is provided. The system includes a control module and a processing device. The control module is configured to obtain an image file representing a pixel having a first pixel size in a first direction and a second pixel size in a second direction, wherein the first pixel size and the second pixel size are the same or different. The processing device is configured to process the mask layer so that a plurality of regions with changed physical properties are generated in the mask layer, and the plurality of regions correspond to a plurality of pixels of the image file. The control module is further configured to control the processing so that the first region size and / or the second region size of the region in the plurality of regions measured in the first direction and the second direction are less than the first pixel size and / or the second pixel size. Additionally or alternatively, the processing device may be configured to process the mask layer so that a plurality of regions with changed physical properties are generated in the mask layer, and the plurality of regions at least include a first region and a second region corresponding to a first pixel and a second pixel directly adjacent to the image file. The control module may be further configured to control the processing device so that the first region and the second region do not overlap in the first direction and / or the second direction.

[0053] The processing means may comprise beam generating means for generating a beam of first electromagnetic radiation. Preferably, the beam has a first and a second beam size. The first and / or second beam size as seen in the first and / or second direction may be smaller than the first and / or second pixel size, respectively, and more preferably in the range of 20% to 95%, preferably in the range of 40% to 80%, of the pixel size.

[0054] The control module can be configured to control the beam generating device, and more specifically to control the wavelength, the first and / or second beam size, the beam power and the duration of the beam, wherein the beam power and / or the first and / or the second beam size and / or the duration can be controlled based on an analysis of the obtained image file.

[0055] The control module may be configured to control the light beam generating device according to any one of the method steps described above in combination with the method. It is further noted that device features corresponding to the above method features may be included in the system. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0057] Figure 1A 1E schematically illustrates an embodiment of the prior art;

[0058] FIG. 2A to FIG. 2C An exemplary embodiment of the method according to the invention is shown;

[0059] FIG. 3A to FIG. 3D Four exemplary embodiments are shown, with a plurality of pixels and their corresponding processing regions for each embodiment;

[0060] 4A and 4B show two embodiments of the prior art, image files, laser beams used, and exposure images;

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

[0062] 5A and 5B show two exemplary embodiments of the present invention, wherein each figure shows an image file used, a laser beam used, and an exposure image on a mask, respectively;

[0063] FIG6A is a top view of an exemplary embodiment of a mask;

[0064] FIG6B is a top view of an exemplary embodiment of a printing plate in an inked state;

[0065] FIG6C is a top view of a printed medium using the printing plate of FIG6B;

[0066] 7A and 7B compare a printed sample using relief printing manufactured according to the prior art embodiment of FIG. 4A and a printed sample using relief printing manufactured according to the exemplary embodiment of the present invention of FIG. 5B , respectively. DETAILED DESCRIPTION

[0067] FIG. 2A to FIG. 2C as well as Figure 3A An exemplary embodiment of the method according to the present invention is shown. Figure 2A In the first step shown, a pixel size corresponding to p (see Figure 3AThe illustrated image file has square pixels 4, so that the first and second pixel sizes seen in a first direction and in a second direction perpendicular to the first direction are the same and equal to p. The illustrated image file contains a substantially circular image area 1 to be printed. The image file resolution corresponding to the pixel size p may be, for example, 4000 dpi. The mask layer is then treated with a beam of first electromagnetic radiation. The beam is suitable for generating a treatment area A, here a hole 2. The generated hole 2 is Figure 2B and having an area size h smaller than the pixel size p, see also Figure 3A Using this beam, a plurality of holes 5 are generated in the mask layer, the plurality of areas corresponding to a plurality of pixels 4 of the image file. A top view of the mask layer is shown in FIG. Figure 2C shown. Figure 3A Shows Figure 2C Four pixels of detail.

[0068] The light beam, in particular the size of the light beam, is selected such that the area size h of the holes 5 in the plurality of holes 5 is smaller than the pixel size p. The plurality of holes 5 comprises at least a first and a second area A1, A2, here first and second holes 5a, 5b corresponding to directly adjacent first and second pixels 4a, 4b of the image file, wherein the first and second holes 5a, 5b are processed by the light beam such that they do not overlap. When referring to directly adjacent pixels, it is meant that the pixels have a common edge, i.e. an edge in the first direction or an edge in the second direction. In other words, in FIG. 2A to FIG. 2C And in the embodiment of 3A, directly adjacent pixels have a common edge with a length corresponding to the pixel size p.

[0069] FIG. 3B to FIG. 3D Other possible pixel sizes and region sizes are shown. Figure 3B In an embodiment, the pixels are square and have a pixel size p. The first and second area sizes h1, h2 are different. In the illustrated embodiment, the area is substantially elliptical and has a first minimum area size h1 extending in a first direction and a second larger area size h2 extending in a second direction perpendicular to the first direction, the first minimum area size h1 being smaller than the pixel size p, and the second larger area size h2 being larger than the pixel size p (h1<p, h2>p). In this way, a first plurality of areas A1 can be formed, which overlap in the second direction but not in the first direction, and a second plurality of areas A2 can be formed in the second direction but not in the first direction, wherein the second plurality does not overlap with the first plurality. In this way, the surface screen pattern will more or less look like a line pattern.

[0070] In another embodiment not shown, the region is substantially elliptical and has a first minimum region size h1 extending in the first direction and a second larger region size h2 extending in a second direction perpendicular to the first direction, the first minimum region size h1 being smaller than the pixel size p, and the second larger region size h2 also being smaller than the pixel size p (h1<p, h2<p). In this way, a plurality of regions A1, A2 that do not overlap in the first and second directions can be formed.

[0071] exist Figure 3C In an embodiment, the pixel is rectangular and has a first pixel size p1 in a first direction and a second pixel size p2 in a second direction perpendicular to the first direction. In addition, the first and second area sizes h1, h2 are different. In the illustrated embodiment, the area is substantially elliptical and has a first minimum area size h1 extending in the first direction and a second larger area size h2 extending in the second direction, the first minimum area size h1 being smaller than the first pixel size p1, and the second larger area size h2 being smaller than the second pixel size p2 (h1<p1, h2<p2). In this way, a plurality of areas A1, A2 that do not overlap in the first and second directions can be formed.

[0072] exist Figure 3D In an embodiment, 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 region sizes h1, h2 may be the same or different. In the illustrated embodiment, the region is substantially circular and has a first region size h1 extending in the first direction and a second region size h2 extending in the second direction, the first region size h1 being greater than the first pixel size p1 and the second region size h2 being less than the second pixel size p (h1>p1, h2<p2). In this way, a first plurality of regions A1 may be formed in the first direction but not overlapping in the second direction, and a second plurality of regions A2 may be formed in the first direction but not overlapping in the second direction, wherein the second plurality does not overlap with the first plurality. In this way, the surface screen pattern will more or less look like a line pattern.

[0073] Figures 4A and 4B show two embodiments of the prior art, an image file (left side), a laser beam used (bottom image) and an exposed image (right side). No surface screening is applied. In the exposed image, adjacent areas overlap because the beam size used is larger than the pixel size. Figure 4C shows another example of the prior art in which surface screening is applied in an image file, wherein the figure shows an image file (upper left), an applied surface pattern (lower left), a modified image file (upper middle), a laser beam used (lower right) and an exposed image on a mask layer (upper right), respectively. In the exposed image of Figure 4C, since the beam size used is larger than the pixel size, adjacent areas corresponding to directly adjacent pixels overlap, but since surface screening is performed in the image file, there are no adjacent areas corresponding to directly adjacent pixels.

[0074] 5A and 5B show two exemplary embodiments of the present invention, wherein each figure shows the image file used (upper left), the laser beam used (lower), and the exposure image on the mask (upper right). FIG. 2A to FIG. 2C as well as Figure 3A The pixel has a square shape with the same pixel size in the first and second directions. The beam used is circular and the beam size is smaller than the pixel size, and no surface screening is performed in the image file.

[0075] FIG6A is a top view of an exemplary embodiment of a mask having a plurality of mask regions 6 corresponding to a plurality of halftone image regions. Each mask region 6 includes a plurality of apertures 5. In this embodiment, the mask regions include adjacent apertures 5a, 5b corresponding to directly adjacent pixels. FIG6B is a top view of an exemplary embodiment of a printing plate made using the mask of FIG6A in an inked state. FIG6C is a top view of a printed medium using the printing plate of FIG6B.

[0076] Figures 7A and 7B compare the printed samples using the relief printing made according to the prior art embodiment of Figure 4A and the printed samples using the relief printing made according to the exemplary embodiment of the present invention of Figure 5B, respectively. It can be seen that the results obtained using the embodiments of the present invention are significantly better than the results obtained according to the prior art embodiment.

[0077] Example:

[0078] In Table 1, three examples of the prior art (Ref. 1 to Ref. 3) are compared with two examples of the present invention (Example 1 to Example 2).

[0079] Different methods and beam sizes were applied to digital printing plate precursors comprising an integral mask layer, which can be ablated by an IR laser beam. Table 1 contains the specific dimensions, beam shapes and intensity distributions, as well as the results obtained for printing (solid ink density).

[0080] Table 1:

[0081]

[0082] Image file resolution (dpi) is the number of pixels per inch in an image file, calculated in one dimension and expressed in dpi (dots per inch) or ppi (pixels per inch). For the example of the table, pixels are square. The pixel size (in microns and in that dimension) is the inverse of the resolution (in dpi) multiplied by 25400.

[0083] The beam diameter (micrometers) is the longest measured distance between two points in the intensity distribution of any cross section of the beam where the intensity is equal to 50% of the maximum intensity in that cross section. The intensity distribution is the intensity distribution of the light generated by a single imaging pixel.

[0084] The intensity profile is the spatial distribution of the light intensity (W / mm2) of the laser beam. Typical profiles can be just Gaussian, just rectangular (top hat) or just trapezoidal. The intensity profile is the intensity distribution of the light generated by a single imaging pixel.

[0085] The beam shape is the two-dimensional (2-D) shape of the cross section of the intensity distribution at a specific intensity value. Typical beam shapes are elliptical or circular, or polygonal (square, rectangular, triangular, hexagonal, ...). The intensity profile is the intensity distribution of the light generated by a single imaging pixel.

[0086] 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 of the surface screen lpi to the classic screen lpi.

[0087] The size of the hole in the mask in micrometers is the size of the hole in the mask resulting from the intensity distribution of the exposure light generated by a single imaging pixel. It is analyzed using a transmitted light microscope and using a transmitted light intensity distribution graph. It is measured as the longest distance in the transmitted intensity distribution between two points in the transmitted intensity distribution where the transmitted intensity is equal to 50% of the maximum transmitted intensity.

[0088] Solid ink density was measured as reflected density on printed samples in the solid areas using a digital densitometer.

[0089] The results of Examples 1 and 2 in Table 1 clearly show that high ink density is achieved in a relatively short time and without the need for manipulation of the image file.

[0090] The above table shows that the surface pattern screening resolution obtainable by the embodiment of FIGS. 5A and 5B is higher than that obtainable by the prior art embodiment ( FIGS. 4A to 4C ), while the file size can be kept small.

[0091] Although the principles of the present invention have been described above in conjunction with specific embodiments, it should be understood that this description is only illustrative and not limiting of the scope of protection determined by the appended claims.

Claims

1. A method for applying a pattern on a mask layer, the method comprising: An image file representing pixels is obtained, the pixels having a first pixel size (p) in a first direction parallel to an edge of the pixels; p1) and having a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first pixel size and the second pixel size are the same (p) or different (p1, p2); processing the mask layer so as to generate a plurality of regions with changed physical properties in the mask layer, the plurality of regions (A) corresponding to a plurality of pixels of the image file, wherein the processing is performed so that a first region size and / or a second region size (h; h1, h2) of a region in the plurality of regions viewed in the first direction and / or the second direction is smaller than the first pixel size and / or the second pixel size (p; p1, p2), respectively; Wherein, the method is performed without manipulating the image file to obtain the surface screen pattern on the mask layer.

2. The method according to claim 1, wherein: The processing is performed so that an area size (h; h1, h2) of an area among the plurality of areas viewed in the first direction and / or the second direction is smaller than the first pixel size and the second pixel size, respectively.

3. A method for applying a pattern on a mask layer, the method comprising: An image file representing pixels is obtained, the pixels having a first pixel size (p) in a first direction parallel to an edge of the pixels; p1) and having a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first pixel size and the second pixel size are the same or different; The mask layer is processed so as to generate a plurality of regions with changed physical properties in the mask layer, the plurality of regions comprising at least a first region and a second region (A1, A2) corresponding to directly adjacent first pixels and second pixels of the image file, wherein the processing is performed so that the first region and the second region do not overlap in the first direction and / or the second direction.

4. The method according to claim 1 or 3, wherein: The plurality of regions corresponds to a plurality of holes or a plurality of regions having a transparency for electromagnetic radiation that differs from the transparency of the untreated mask material of the mask layer.

5. The method according to claim 1 or 3, wherein: The first region size and / or the second region size are / is in the range of 20% to 99% of the first pixel size and / or the second pixel size, respectively.

6. The method according to claim 1 or 3, wherein: The step of processing the mask layer is performed using a beam of first electromagnetic radiation.

7. The method according to claim 6, wherein: The light beam has a first beam size and a second beam size in the first direction and the second direction, wherein the first beam size and / or the second beam size are respectively smaller than the first pixel size and / or the second pixel size, and the first beam size and the second beam size are respectively the longest distances of the intensity distribution between two points in the intensity distribution of the cross section of the light beam in the first direction and the second direction where the intensity is equal to 50% of the maximum intensity in the cross section.

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

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

10. The method according to claim 6, wherein: The light beam used to generate the area corresponding to the pixels of the first area of ​​the image document is different from the light beam used to generate the area corresponding to the pixels of the second area of ​​the image document.

11. The method according to claim 6, wherein: The first beam size and / or the second beam size and / or the beam power of the light beam are selected according to the tone values ​​of pixels of the halftone area of ​​the image file.

12. The method according to claim 6, wherein: The cross-section of the light beam is circular, elliptical or polygonal, and / or the intensity distribution of the light beam is Gaussian, trapezoidal or rectangular.

13. The method according to claim 6, wherein: The mask layer is initially substantially opaque to the first electromagnetic radiation of the light beam; and / or wherein the mask layer undergoes a change in transparency due to ablation, and / or a color change, and / or a polarization change when exposed to the first electromagnetic radiation.

14. The method according to claim 1 or 3, wherein: The step of controlling processing of the mask layer makes a pattern formed by a plurality of regions corresponding to at least one image region for image regions of the image contained in the image file, wherein the pattern is any one of: a regular or periodic pattern, a random pattern or a combination thereof.

15. The method according to claim 1 or 3, wherein: Control the step of processing the mask layer so that for an image area of ​​the image contained in the image file, the first area size and / or the second area size and / or the distribution of the area are the same or different from the area near the center of the image area and the area near the edge of the image area.

16. The method according to claim 1 or 3, wherein: The step of processing the mask layer is controlled so that, for an image area of ​​the image contained in the image file, the density of the area is set according to the size of the image area.

17. The method according to claim 1 or 3, wherein: Processing of the mask layer is controlled such that, for an image region of an image contained in the image file, a density of the region increases or decreases from a center of the image region to an edge of the image region.

18. The method according to claim 14, wherein: The image area corresponds to a halftone area or a solid area.

19. The method according to claim 1 or 3, wherein: The obtained image file is not manipulated by changing the image file resolution and / or is not manipulated by removing pixels to generate the plurality of regions within the image file.

20. The method according to claim 1 or 3, wherein: The image file resolution is in the range of 300 dpi to 20,000 dpi.

21. The method according to claim 1 or 3, wherein: The mask layer is included in a printing plate precursor; wherein the printing plate precursor comprises one or more of the following layers: a support layer, a photosensitive layer, a protective layer, a barrier layer, a diffractive layer, a diffuser layer, an adhesive layer or a combination thereof.

22. A method of forming an imaged layer composition, the method comprising the steps of: combining the mask layer and the substrate layer to form a layer composition, A method according to any preceding claim, applying a pattern to the mask layer, The layer composition is processed such that the substrate layer undergoes a property change in a plurality of substrate regions corresponding to the plurality of regions created in the patterned mask layer, thereby forming an imaged layer composition.

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

24. The method according to claim 22 or 23, further comprising at least one step of treating the layer composition to obtain a further treated layer composition by means of a property change.

25. The method according to claim 22 or 23, wherein: After or before the step of combining the mask layer and the substrate layer, a step of applying a pattern to the mask layer is performed.

26. The method according to claim 22 or 23, wherein: The substrate layer includes a support layer, a photosensitive layer, a protective layer, an adhesive layer, a barrier layer, a sliding layer, a roughening layer, a layer that changes electric field polarization, or a combination thereof.

27. The method according to claim 22 or 23, wherein: Combining the mask layer with the substrate layer includes attaching the mask layer to the substrate layer or using the mask layer and the substrate layer as an integral layer of the substrate.

28. The method of claim 23, wherein: The wavelength of the second electromagnetic radiation is in the range of 200 nm to 2000 nm.

29. The method according to claim 22 or 23, wherein: The property change of the substrate layer is solidification, solubility change, color change, refractive index change, transmission change, polarization change, or a combination thereof.

30. The method of claim 29, wherein: The solubility change is achieved by polymerization, cross-linking, depolymerization, cleavage of polymer chains, cleavage of protecting groups or a combination thereof.

31. The method according to claim 22 or 23, wherein: The imaged layer composition is a relief precursor.

32. The method of claim 24, wherein the further processed layer composition is a printing plate.

33. A component of a mask and a computer-readable storage medium, wherein the computer-readable storage medium stores an image file representing pixels, wherein the pixels have a first pixel size (p; p1) in a first direction parallel to an edge of the pixels and a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first pixel size and the second pixel size are the same or different, and the mask comprises a mask layer having a plurality of regions with changed physical properties, wherein the plurality of regions correspond to a plurality of pixels of the image file, wherein a first region size and / or a second region size (h; h1, h2) of a region in the plurality of regions measured in the first direction and / or the second direction are respectively smaller than the first pixel size and / or the second pixel size, and wherein the image file is not manipulated to obtain a surface screen pattern on the mask layer.

34. A component of a mask and a computer-readable storage medium, wherein the computer-readable storage medium stores an image file representing pixels, wherein the pixels have a first pixel size (p; p1) in a first direction parallel to an edge of the pixels and a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first pixel size and the second pixel size are the same or different, and the mask comprises a mask layer having a plurality of regions with changed physical properties, wherein the plurality of regions include at least a first region and a second region corresponding to adjacent first and second pixels of the image file, wherein the first region and the second region do not overlap in the first direction and / or the second direction.

35. An assembly according to claim 33 or 34, wherein The first region size and / or the second region size are / is in the range of 20% to 99% of the first pixel size and / or the second pixel size, respectively.

36. An assembly according to claim 33 or 34, wherein The plurality of regions are a plurality of holes.

37. An assembly according to claim 33 or 34, wherein The mask layer is provided with: a first image region, the first image region comprising at least two first adjacent regions each having a first surface area; and a second image region, the second image region comprising at least two second adjacent regions each having a second surface area, the first surface area being different from the second surface area, the first surface area being at least 5% higher than the second surface area.

38. An assembly of a relief precursor and a computer-readable storage medium, the computer-readable storage medium storing an image file representing pixels, the pixels having a first pixel size (p; p1) in a first direction parallel to an edge of the pixel and a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first pixel size and the second pixel size are the same or different, the relief precursor comprising a substrate layer having a plurality of convex areas, the plurality of convex areas corresponding to a plurality of pixels of the image file, wherein a first convex area size and / or a second convex area size of a convex area in the plurality of convex areas measured in the first direction and / or the second direction is smaller than the first pixel size and / or the second pixel size, the first convex area size and / or the second convex area size being measured at a top surface of the convex area, wherein the image file is not manipulated to obtain a surface screen pattern on a mask layer.

39. A component of a relief precursor and a computer-readable storage medium, wherein the computer-readable storage medium stores an image file representing pixels, wherein the pixels have a first pixel size (p; p1) in a first direction parallel to an edge of the pixels and a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first pixel size and the second pixel size are the same or different, and the relief precursor includes a substrate layer having a plurality of convex areas, wherein the plurality of convex areas at least include a first convex area and a second convex area corresponding to a first pixel and a second pixel directly adjacent to the image file, wherein the first convex area and the second convex area do not overlap in the first direction and / or the second direction.

40. A system for applying a pattern on a mask layer, the system comprising: a control module configured to obtain an image file representing pixels having a first pixel size (p; p1) in a first direction parallel to an edge of the pixels and a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first pixel size and the second pixel size are the same or different; a processing device configured to process the mask layer so as to generate a plurality of regions with changed physical properties in the mask layer, the plurality of regions corresponding to a plurality of pixels of the image file; wherein the control module is further configured to control the processing so that a first region size and / or a second region size of a region in the plurality of regions measured in the first direction and the second direction are smaller than the first pixel size and the second pixel size, respectively; wherein the controlling is performed without manipulating the image file to obtain a surface screen pattern on the mask layer.

41. A system for applying a pattern on a mask layer, the system comprising: a control module configured to obtain an image file representing pixels having a first pixel size (p; p1) in a first direction parallel to an edge of the pixels and a second pixel size (p; p2) in a second direction perpendicular to the first direction, wherein the first pixel size and the second pixel size are the same or different; a processing device configured to process the mask layer so as to generate a plurality of regions with changed physical properties in the mask layer, the plurality of regions comprising at least a first region and a second region corresponding to first and second pixels directly adjacent to the image file; The control module is further configured to control the processing device so that the first area and the second area do not overlap in the first direction and / or the second direction.

Images