Method and system for imaging a mask layer

Abstract

A method for preparing a relief plate and printing on a substrate such as corrugated cardboard using the relief plate, comprising the steps of: providing a mask layer; obtaining a halftone raster image file having imaged pixels and non-imaged pixels at a first resolution R1, wherein a first pitch P1 corresponds to the first resolution R1; imaging the mask layer according to the halftone raster image file, such that the imaged spots have a maximum dimension less than (√2*P1); preparing a relief plate using the imaged mask layer; transferring ink to the relief plate using an anilox roller; and transferring the ink from the relief plate to a substrate, wherein the first resolution R1 is less than 2000 dpi and the volume density of the anilox roller is 5 cm³. 3 / m 2 That is the method.

Description

[Technical Field]

[0001] The field of the present invention relates to methods, control modules, and computer programs for imaging mask layers, and for controlling the imaging of mask layers, particularly mask layers of printing plate precursors used to obtain relief plates, and relief plates particularly suitable for printing on uneven surfaces such as corrugated cardboard. The field of the present invention further relates to systems for processing printing plate precursors to obtain relief plates and for printing on substrates, particularly substrates with uneven surfaces, using such relief plates. The field of the present invention relates particularly to the printing of grayscale images. [Background technology]

[0002] Flexographic printing, or letterpress printing, is a printing technique commonly used for mass printing. A flexographic or letterpress printing plate is a relief plate in which image elements protrude from non-image elements to generate an image on a recording medium such as paper, cardboard, film, foil, or laminate. Cylindrical printing plates or sleeves may also be used.

[0003] Various methods exist for creating printing plate precursors for flexographic or letterpress printing plates. Conventionally, printing plate precursors for flexographic or letterpress printing plates are created from a multilayer substrate comprising a backing layer and one or more photocurable layers. These photocurable layers are imaged by exposure to electromagnetic radiation through a mask layer containing image information, or by direct and selective exposure to light, in order to obtain a relief plate.

[0004] In flexographic or letterpress printing, ink is transferred from a plate to the printing medium. More specifically, the ink is transferred only to the relief areas of the plate via anilox rollers, and not to the non-relief areas. During printing, the ink in the relief areas is transferred to the printing medium. Flexographic printing may also be called a binary system, and when the relief areas come into contact with the printing surface, a nearly uniform color area is obtained. Grayscale images are usually created using halftone processing. Grayscale refers to the amount of a color that is reproduced when a plate is printed with a particular color. For example, a printing plate may have different halftone dot areas to print at different densities in those areas. Halftone processing is a well-known process that uses a relief plate with multiple solid line dots per unit area, and reproduces gray tones by changing the frequency of the dots per unit area, the size of the dots per unit area, or both.

[0005] To increase the amount of ink transferred and thus the so-called ink density on the substrate, additional, very fine structures are added to the surface of the printing area, i.e., the relief area. This surface screening is typically achieved by adding the fine structures to a raster image file, which is then transferred to the corresponding mask used for exposure.

[0006] International Publication No. 2021 / 110831 A1, in the name of the applicant, describes an example of an existing method for creating a relief plate, as shown in Figures 1A to 1E. Figure 1A shows the contents of a raster image file having an image file resolution corresponding to, for example, a pixel size p (corresponding to pitch) of 6.35 microns. The resolution of the image file may be, for example, 4000 dpi (= 25400 * 1 / p (in microns)). Next, the raster image file is manipulated using a surface screen pattern shown in Figure 1B. The surface screen pattern is applied to image region 1, resulting in a modified raster image file shown in Figure 1C. As shown in Figure 1C, the resulting image region 1' contains fewer pixels 4' to be printed, and the pixels 4' to be printed are spaced apart from each other by a distance d. Based on the modified raster image file in Figure 1C, a mask is prepared. More specifically, for each pixel 4' to be printed, a hole or transparent region 5 is placed within the mask. This can be done using a beam of electromagnetic radiation. As shown in Figure 1D, such a beam generates holes 2 larger than the size of pixel 4'. The resulting image on the mask is shown in Figure 1E. Thus, according to the method shown in Figures 1A to 1E, surface screening is obtained by modifying the original raster image file, e.g., a TIFF file, using software, typically raster image processing techniques, which usually results in a larger file size.International Publication No. 2021 / 110831 A1 further discloses an improved method for processing a raster image file, comprising the steps of: receiving a raster image file comprising image data of multiple pixels; analyzing the image data of the raster image file; determining control data and, optionally, at least one new raster image file; and, based on the analyzed image data, the control data being data for controlling the settings of an imaging device to change the physical properties of the generated imaging features corresponding to one or more of the multiple pixels; and outputting the raster image file and / or the new raster image file, along with the control data, to an imaging device for imaging a relief precursor. Image quality can be improved in this way. For example, imaging may be controlled in different ways depending on whether the image data includes text and / or photographs and / or barcodes and / or large continuous areas.

[0007] In general printing processes, a combination of high-resolution images, such as 4000-6000 dpi, and surface screening is used to obtain good print results. However, the inventors have pointed out that when printing grayscale on substrates with uneven surfaces, such as corrugated cardboard, the unevenness may be visible through the printed layer. For example, in the case of corrugated cardboard, the corrugated structure may be visible through the printed layer. This effect is called fluting. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2021 / 110831 A1 [Overview of the project] [Problems that the invention aims to solve]

[0009] The object of the embodiments of the present invention is to provide a method, control module, computer program, and system that can improve image quality when printing grayscale images, particularly when printing grayscale images on substrates having an uneven surface, such as corrugated cardboard or wallpaper.

[0010] According to a first embodiment, a method is provided for preparing a relief plate and printing on a substrate, particularly an uneven substrate such as corrugated cardboard, using the relief plate. The method includes the steps of: providing a mask layer; obtaining a halftone raster image file comprising imaged pixels and non-imaged pixels at a first resolution R1, wherein a first pitch P1 corresponds to the first resolution R1; imaging the mask layer according to the halftone raster image file such that the imaged spots have a maximum dimension (D) smaller than (√2*P1), preferably smaller than P1; preparing a relief plate using the imaged mask layer; and transferring ink to the relief plate using an anilox roller, and transferring the ink from the relief plate to the substrate. The first resolution R1 is preferably smaller than 2000 dpi, more preferably smaller than 1700 dpi, and even more preferably smaller than 1500 dpi. The volume density of the anilox roller is 5 cm³. 3 / m 2 It is preferable that it be greater than 7 cm 3 / m 2 It is more preferable that the above conditions are met. The volume density is 20 cm³. 3 / m 2 It is preferable that it be less than [a certain value].

[0011] While anilox rollers with fairly high volume density are typically used for printing on corrugated cardboard, the inventors discovered that using a relatively low first resolution R1, rather than the high resolution used in the prior art, combined with a spot size that results in a finely raised surface structure on the dots, improves the printing results. This is thought to be because the imaged spots do not completely overlap, and the fine raised areas on the corresponding relief plate are large enough to be covered by the ink from the anilox roller, effectively concealing the uneven structure of the substrate, at least to an appropriate extent. The specified volume density usually allows for an appropriate number of raised areas per cell of the anilox roller, i.e., neither too few nor too many raised areas, resulting in sufficient relief between the raised areas and good ink transfer. Furthermore, the relatively low resolution allows for faster imaging. This counterintuitive technique is particularly useful when printing grayscale on substrates with uneven surfaces.

[0012] Note that the pitch corresponds to the distance between the centers of adjacent pixels in a row, and this distance is usually equal to the pixel size. The image settings used for imaging are selected such that the imaged spots have a maximum dimension (D) less than (√2*P1), thereby exposing the relief precursor through the imaged mask layer, and after developing the exposed relief precursor, a raised surface structure surrounded by valleys is generated on the printing relief corresponding to the dots in the halftone region.

[0013] The number of lines of the anilox roller is preferably less than 300 lines / cm (lpcm), and more preferably less than 200 lines / cm. In other words, the cells of the anilox roller are relatively large, and the pitch Pa corresponding to the number of lines is usually considerably larger than the first pitch P1 corresponding to the first resolution. For example, a line count of 200 lpcm corresponds to a pitch Pa = 10,000 / 200 microns = 50 microns, while a resolution of 1500 dpi corresponds to a first pitch P1 = 25,000 / 1,500 microns = 16.9 microns. The number of lines preferably corresponds to the anilox pitch Pa, and during the acquisition step, the first resolution R1 is selected such that Pa is greater than 1.5*P1, and more preferably is between 2*P1 and 10*P1.

[0014] The number of lines measures the fineness of the pattern of the anilox roller. The number of lines measures the number of cells engraved per centimeter or per inch. In Europe, the standard is lpcm, i.e., the number of lines per centimeter. In the United States, the standard is lpi, i.e., the number of lines per inch. Usually, the measurement is performed in the direction in which the most cells can be counted per centimeter.

[0015] Imaging is preferably performed such that the maximum dimension of the imaged spot is smaller than P1 and / or larger than P1 / 3. In such embodiments, since the image spots do not overlap each other, an appropriate fine surface structure for printing a uniform area can be generated.

[0016] The anilox roller has a plurality of ink metering cells on its surface. These cells are usually arranged in a regular pattern of a predetermined frequency (represented by the number of lines per centimeter, lpcm) and have a uniform depth and shape. Usually, these cells are created by mechanically processing or laser engraving the cylindrical surface of the roller. The amount of ink supplied by the anilox roller is controlled by the size of the cells.

[0017] Optionally, before or during imaging of the mask layer, a sampling pattern is overlaid on the halftone raster image file, so that only a part of the pixels to be imaged are imaged. However, although this method may be preferred for some applications, in other applications, good results may be obtained even when the sampling pattern is not overlaid before or during imaging of the mask layer.

[0018] It should be further noted that the sampling pattern may be applied in a specific area of the halftone raster image file and not in other areas. For example, the sampling pattern may be added for tone values above a threshold, and the sampling pattern may not be overlaid for tone values below the threshold.

[0019] Therefore, in order to obtain a sampled raster image file in which some of the imaging pixels of the image file are changed to non-imaging pixels, the sampling pattern may be overlaid on the pixels of the halftone raster image file before imaging, and the imaging is based on the sampled raster image file. Also, even in that case, the sampling pattern may be applied in a specific area of the halftone raster image file and not in other areas. Usually, since the first resolution is quite low, it is preferable to use a relatively high-density sampling pattern such as a checkerboard pattern. Instead of the sampled raster image file, it is also possible to overlay the sampling pattern during imaging, and in this case, the sampling pattern is added "on the fly" during imaging.

[0020] A sampling pattern may be a repetition of blocks consisting of one or more imaged pixels and one or more non-imaged pixels. For example, a sampling pattern may be one of the following, or a combination thereof: a single-pixel pattern such as a single-pixel checkerboard pattern where each imaged pixel is surrounded by eight non-imaged pixels; a multi-pixel pattern such as a multi-pixel checkerboard pattern where a cluster of four imaged pixels or four non-imaged pixels corresponds to one square on a checkerboard; a line pattern; a dash pattern (e.g., a dotted line); a circle pattern; a grid pattern.

[0021] Optionally, before imaging, and based on the halftone raster image file, or the sampled raster image file if a sampling pattern is used, a modified raster image file may be generated to have at least 2 bits per pixel. At least 2 bits per pixel indicate whether the pixel is an unimaged pixel, an imaged pixel imaged with a first imaging setting, an imaged pixel imaged using a second imaging setting different from the first, or optionally, an imaged pixel imaged using a third imaging setting different from the first and second. The imaging step is then performed based on the modified raster image file. These features consolidate the instructions for the image settings used into a single modified raster image file. During the imaging of the mask layer, there is no need to refer to other files and / or prepare multiple raster image files; only the information needs to be extracted from this modified image file. Therefore, generating such a modified raster image file allows for convenient instruction of the imager while enabling the modification of imaging settings. In this way, imaging settings can be conveniently changed during imaging.

[0022] The anilox roller preferably has a hexagonal cell pattern.

[0023] The first resolution R1 is preferably 700 to 1500 dpi.

[0024] According to a second embodiment, a method is provided for imaging a mask layer for obtaining a relief plate for printing on a substrate. The method includes the steps of: providing a mask layer; obtaining a halftone raster image file having imaged pixels and non-imaged pixels at a first resolution R1; improving the resolution of the halftone raster image file to obtain a high-resolution raster image file having high-resolution imaged pixels and high-resolution non-imaged pixels at a second resolution R2 higher than the first resolution R1; superimposing a sampling pattern having a repetition period equal to the first resolution R1 onto the high-resolution raster image file so that only a portion of the high-resolution imaged pixels are imaged; and imaging the mask layer according to the high-resolution raster image file having the superimposed sampling pattern.

[0025] This method may be slower than the method of the first embodiment, but it has the advantage of being able to use a "normal" resolution for R2, and therefore existing sampling patterns can be used. Furthermore, it can achieve similar effects to the method of the first embodiment.

[0026] Sampling patterns may be applied before imaging, generating a sampled high-resolution raster image file for use in imaging, or they may be applied "on the fly" during imaging. Note that sampling patterns may be applied to specific areas of a halftone raster image file while not being applied to other areas. For example, sampling patterns may be added to tonal values ​​above a threshold, but not superimposed on tonal values ​​below a threshold. Typically, since the second resolution is quite high, it is preferable to use sampling patterns that are repetitions of blocks where there are more non-imaged pixels than imaged pixels.

[0027] It should be noted that starting with a low-resolution raster image file with resolution R1 and then increasing the resolution to R2 can mitigate or avoid problems such as interference / moire phenomena compared to starting with a high-resolution raster image file with resolution R2.

[0028] In a first aspect, in printing on corrugated cardboard, the inventors discovered that when using a relatively low first resolution R1, improvements in printing results can be obtained by combining increased resolution with the use of sampling patterns. This is thought to be because the imaged spots create raised areas on the relief plate, which are large enough to be covered by ink from the anilox roller, effectively concealing the uneven structure of the substrate, at least to a suitable extent. This counterintuitive technique is particularly useful when printing grayscale on substrates with uneven surfaces.

[0029] The second resolution R2 is preferably a multiple of the first resolution R1. More preferably, the second resolution R2 is at least four times the first resolution R1.

[0030] The step of imaging the mask layer according to a high-resolution halftone raster image file is preferably performed such that the imaged spots have a maximum dimension (D) greater than P2, and more preferably so that the maximum dimension (D) is greater than (√2 × P2). In other words, the imaged spots are "boosted" to a size that partially or completely overlaps adjacent imaged spots. In this way, adjacent spots may form one larger bulge rather than individual smaller bulges, which may result in better edges for the print function.

[0031] The sampling pattern superimposed on a high-resolution raster image file is a repetition of blocks consisting of one or more imaged pixels and one or more non-imaged pixels. Preferably, R2 is at least three times R1, and the sampling pattern is formed by a repetition of blocks consisting of one or more adjacent imaged pixels surrounded by at least eight non-imaged pixels. For example, if R2 = 3 * R1, the sampling pattern may be a repetition of blocks having a single imaged pixel surrounded by eight non-imaged pixels, and if R2 = 4 * R1, the sampling pattern may be a repetition of blocks of four adjacent imaged pixels (forming a square) surrounded by twelve non-imaged pixels. Note that imaged pixels may be positioned in the center of the block as in the example, but they may also be positioned off-center. For example, if R2 = 3 * R1, the sampling pattern may be a repetition of blocks with a single imaged pixel in the corner and eight non-imaged pixels filling the rest of a 3x3 pixel block.

[0032] Optionally, before imaging, a high-resolution raster image file is generated that has been modified to have at least 2 bits per pixel, based on a high-resolution raster image file having a sampling pattern, wherein each of the at least 2 bits indicates whether the pixel is a non-imaged pixel, an imaged pixel imaged with a first imaging setting, an imaged pixel imaged using a second imaging setting different from the first imaging setting, or optionally, an imaged pixel imaged using a third imaging setting different from the first and second imaging settings, and imaging is performed based on the modified raster image file.

[0033] A method according to a second embodiment may further comprise the steps of preparing a relief plate using an imaged mask layer, and transferring ink to the relief plate using an anilox roller, thereby transferring the ink from the relief plate to a substrate.

[0034] Similar to the first aspect, the volume density of the anilox roller is preferably 5 cm 3 / m 2 or more, and preferably 7 cm 3 / m 2 or more. The number of lines of the anilox roller is preferably less than 300 lines per centimeter, and preferably less than 200 lines per centimeter. For example, the number of lines may correspond to the anilox pitch Pa, and during the acquisition step, the first resolution R1 is selected such that Pa is greater than 1.5*P1, and more preferably 2*P1 to 10*P1.

[0035] The preferred features shown below can be used in both the method of the first aspect and the method of the second aspect.

[0036] The step of obtaining the halftone raster image file is preferably the result of raster image processing of a non-raster image file such as a pdf or ps file in order to directly obtain a halftone raster image file having the first resolution R1. In this way, the influence of moire phenomena / interference can be reduced or avoided.

[0037] Imaging can be performed such that all imaged spots have substantially the same dimensions and / or shape, or the dimensions and / or shape of the imaged spots are changed according to a regular or irregular pattern.

[0038] Such different dimensions and / or shapes can be achieved by controlling the imaging settings, particularly by controlling any one or more of the following imaging settings. The intensity value used to generate the imaging feature corresponding to the imaging pixel, for example, the intensity value for controlling the beam used for imaging the imaging pixel in the halftone region, The time interval used to generate the imaging feature corresponding to the imaging pixel, for example, the on-time value for controlling the beam used for imaging the imaging pixel in the halftone region, Beam diameter value or beam shape value for controlling the beam used for imaging pixels, Multiple passes used for imaging pixels in the halftone region. Display of an exposure head used to generate imaging features or groups of imaging features corresponding to one pixel or group of pixels among multiple exposure heads.

[0039] The imaging step preferably includes ablation of the mask layer, and more preferably includes ablation using a laser.

[0040] This method preferably further includes the step of providing a mask layer on a photopolymerizable layer of a relief precursor, either before or after the imaging step.

[0041] The mask layer may be a separate layer applied to the relief precursor after removal of a protective layer that may be optionally present, or it may be an integral layer of the precursor that is in contact with either the relief layer or an optionally present layer on the relief layer and covered by an optional protective layer. The mask layer may be a commercially available negative film, which can be manufactured, for example, by a photographic method based on silver halide chemistry. The mask layer may be a composite layer material in which a transparent layer is formed on an originally opaque layer by image-based exposure, as described in, for example, EP3 139 210A1, EP1 735 664B1, EP2987 030A1, and EP2 313 270B1. This can be done by writing directly onto the relief-forming layer, for example, by ablating an opaque layer onto a transparent carrier layer, as described in U.S. Patent No. 6,916,596, EP816 920B1, or by selectively coating an opaque layer onto a transparent carrier layer, as described in EP992 846B1, or by printing opaque ink by inkjet, as described in EP1 195 645A1.

[0042] The mask layer is an integral layer of the relief precursor and is preferably positioned in direct contact with the relief-forming layer or a functional layer, preferably a barrier layer, placed on the relief-forming layer. Furthermore, the integral mask layer can be imaged by ablation and further removed by solvent, or by heating and adsorption / absorption. For example, the layer may be heated and liquefied by selective irradiation with high-energy electromagnetic radiation to generate an image-based structured mask, which may be used to transfer the structure to the relief precursor. For this purpose, it is opaque in the ultraviolet region and can absorb radiation in the visible-infrared region, thereby heating the layer and causing ablation. After ablation, the mask layer also forms a relief, usually with a lower relief height, for example, in the range of 0.1 to 5 μm. In one embodiment, the optical density of the mask layer is in the range of 1 to 5, preferably 1.5 to 4, and particularly preferably 2 to 4, in the ultraviolet region of 330 to 420 nm and / or the visible-infrared region of 340 to 660 nm. The thickness of a laser-ablated mask layer is generally 0.1 to 5 μm. A layer thickness of 0.3 to 4 μm is preferred, and 1 μm to 3 μm is particularly preferred. The laser sensitivity of the mask layer (1 cm) 2 (Measured as the energy required to ablate the layer) is 0.1-10 mJ / cm³ 2 It may be 0.3-5 mJ / cm². 2 Preferably, the concentration is 0.5 to 5 mJ / cm². 2 It is particularly preferable that this be the case.

[0043] The step of preparing a relief plate using an imaged mask layer preferably includes exposing a photopolymerizable layer of the relief precursor through the mask layer and developing the relief precursor to obtain a relief plate. The relief plate may be a flexographic plate, a letterpress plate, a planar plate, or a cylindrical plate.

[0044] According to another exemplary embodiment, the method further includes the step of detecting at least one internal region and at least one edge region in an image file, wherein different imaging settings may be used for the at least one internal region and at least one edge region, and the at least one internal region and at least one edge region may comprise an internal region and an edge region of a dot in a halftone region.

[0045] A raster image file may be a 1BPP (1 bit / pixel) file, or a multilevel image file with multiple bits per pixel (for example, pixels may have various gray levels). A raster image file may be in one of the following file formats: TIFF, LEN, JPEG, JPG, BMP, JDF, PNG, etc.

[0046] In an exemplary embodiment, a RIP (Raster Image Processing) module converts a source image file, such as a PDF or PS file, into a raster image file corresponding to a raster image file having the aforementioned first resolution R1. A RIP module is a component used in image processing that generates raster image files, also known as bitmaps, which are pixel-based formats. The source image file may be a page description in a high-level page description language such as PostScript, Portable Document Format, or XPS, or another bitmap. In the latter case, to generate the output bitmap, the RIP applies either a smoothing or interpolation algorithm to the input bitmap. Raster image processing is the process of converting vector-based digital information, such as a PostScript file, into a high-resolution raster image file. Typically, a RIP module is implemented as a software component of an operating system or as a firmware program executed on a microprocessor. A RIP module may further have layout capabilities. If multiple smaller images need to be printed, these images may be grouped based on a print pattern. This grouping can also be performed by a RIP module.

[0047] Optionally, a raster image file may include raster image processing data, i.e., bitmap data, and vector coordinates corresponding to image patches. Alternatively, a raster image file containing raster image processing data may be part of a job file further comprising vector coordinates. The raster image processing data, i.e., bitmap data, and associated vector coordinates corresponding to image patches can be used as input for processing the raster image processing data to automatically create one or more raster-processed image patches. Each such image patch may be marked with one or more registration marks, and one or more marked image patches and the vector coordinates corresponding to each image patch can be stored in a processing file for creating a print plate. Mounting device information, barcodes, and other information may also be associated and stored in the processing file. In one embodiment, bitmap information may be stored in a first layer of a template file, and the vector coordinates of each image patch may be stored in a second layer of the template file. In another embodiment, bitmap information may be stored in a first file, and the vector coordinates of each image patch may be stored in a second file associated with the first file.

[0048] In another embodiment, a relief plate obtained by the method described in any of the embodiments described above is provided.

[0049] In another embodiment, a computer program, a computer program product, or digital storage means is provided, which comprises computer-executable instructions for controlling any of the methods described above when the program is executed on a computer.

[0050] In a further embodiment, a system is provided for processing a relief precursor, comprising: an imager configured to image a mask layer; an exposure means configured to expose a relief precursor through the imaged mask layer; a developing means configured to remove at least a portion of unexposed material from the relief precursor; and a control module for controlling the imager according to any of the embodiments described above. The imager may be a device for selectively removing a portion of the mask layer, changing the transmittance of the mask layer, or selectively adding an opaque material to a substrate layer or relief precursor. Preferably, the imager removes a portion of the mask layer or changes the transmittance of the mask layer, which can be achieved by using a beam of electromagnetic radiation. Most preferably, the imager removes a portion of the mask layer by ablation, and a beam of electromagnetic radiation is used. The wavelength of the electromagnetic radiation beam is preferably in the range of 700 nm to 12,000 nm.

[0051] Optionally, the system further comprises any one or more of the following configured to transport relief precursors: at least one transport system, storage device, drying system, post-exposure processing device, cutting device, mounting station, and heater. Optionally, the system may also comprise a printing station for supplying ink to the acquired relief plate and transferring the ink to the substrate.

[0052] Optionally, the system further comprises an anilox roller configured to apply ink to the acquired relief plate. The anilox roller may have any one of the features disclosed above in connection with the method.

[0053] The technical advantages described for the embodiments according to the first and second aspects above also apply to the embodiments of the present system, with necessary modifications.

[0054] The accompanying drawings are used to illustrate currently preferred, non-limiting, exemplary embodiments of the methods, control modules, and systems of the present invention. The above and other advantages of the features and objectives of the present invention will become clearer and the invention will be better understood when read in conjunction with the following detailed description and the accompanying drawings. [Brief explanation of the drawing]

[0055] [Figure 1] This figure schematically illustrates an exemplary embodiment of a method for imaging a mask layer. [Figure 2A] This is a schematic diagram illustrating a system for printing using an anilox roller. [Figure 2B] This figure shows several parameters that characterize anilox lorah. [Figure 2C] This diagram shows different types of anilox rollers. [Figure 3] This figure schematically illustrates another exemplary embodiment of a method for imaging a mask layer. [Figure 4] This figure schematically illustrates another exemplary embodiment of a method for imaging a mask layer. [Figure 5A] This figure shows an exemplary embodiment of an imaged spot that can be obtained using the embodiments shown in Figures 1, 3, and 4. [Figure 5B] This figure shows an exemplary embodiment of an imaged spot that can be obtained using the embodiments shown in Figures 1, 3, and 4. [Figure 5C] This figure shows an exemplary embodiment of an imaged spot that can be obtained using the embodiments shown in Figures 1, 3, and 4. [Figure 5D] This figure shows an exemplary embodiment of an imaged spot that can be obtained using the embodiments shown in Figures 1, 3, and 4. [Figure 5E] This figure shows an exemplary embodiment of an imaged spot that can be obtained using the embodiments shown in Figures 1, 3, and 4. [Figure 6]This figure schematically illustrates another exemplary embodiment of a method for imaging a mask layer. [Figure 7A] This figure shows the printing results when using the conventional method (Figure 7A). [Figure 7B] This figure shows the printing results when using the method shown in Figure 1 (Figure 7B). [Figure 7C] This figure shows the printing result when using the method shown in Figure 3 (Figure 7C). [Figure 8] This is a schematic diagram showing an exemplary embodiment of a system for manufacturing relief plate printing plates / sleeves. [Figure 9] This is a schematic diagram of an exemplary embodiment of a control module located downstream of a RIP module. [Figure 10] This is a schematic diagram of another exemplary embodiment of the control module. [Figure 11] This figure schematically illustrates another embodiment of a method for imaging a mask layer. [Figure 12A] This figure shows an embodiment in which pixels are imaged using a spot dimension D of 14 microns, starting from a high-resolution file. [Figure 12B] This figure shows an embodiment that starts with a high-resolution file, reduces its resolution, and then uses a spot dimension D of 14 microns. [Figure 12C] This figure shows an embodiment that starts with a low-resolution raster image file. [Modes for carrying out the invention]

[0056] Figures 1 and 2A to 2C illustrate a first embodiment showing a method for preparing a relief plate and printing on a substrate, particularly an uneven substrate such as corrugated cardboard, using the relief plate. First, the plate is imaged as shown in Figure 1. The method comprises the steps of: providing a mask layer; obtaining a halftone raster image file having imaged pixels and unimaged pixels at a first resolution R1 (see Part 1 of Figure 1); and imaging the mask layer according to the halftone raster image file such that the imaged spots have a maximum dimension D smaller than (√2*P1), preferably smaller than P1, where the first pitch P1 corresponds to the first resolution R1 (see Part 2 of Figure 1). In the example in Figure 1, the file contains a circular uniform area, but it is understood that the file may contain any image. On the right side of Figure 1, six imaged pixels of the file are shown to more clearly illustrate the first pitch P1 and the spot dimension D. The first resolution R1 is preferably less than 2000 dpi, preferably less than 1700 dpi, and more preferably less than 1500 dpi. For example, the first resolution R1 is 700 to 1500 dpi. For example, if R1 = 1270 dpi, the first pitch P1 = 25400 / 1270 microns = 20 microns.

[0057] Following the step of imaging the mask layer, the imaged mask layer is used to prepare a relief plate according to a well-known method, which typically involves exposing the relief precursor to ultraviolet light through the mask and developing the exposed relief precursor by, for example, washing or thermal development. The completed relief plate P can then be used for printing, as shown in Figure 2A.

[0058] In the exemplary embodiment shown in Figure 2A, the printing plate P is mounted on the mounting cylinder 30 and positioned in contact with the anilox roller 10 so that ink can be transferred to the relief plate P. The anilox roller 10 draws up ink from the ink container 20 and transfers the ink to the relief plate P. The ink is then transferred from the relief plate P to the substrate S. The volume density of the anilox roller 10 is 5 cm³. 3 / m 2 It is preferable that it be greater than 7 cm 3 / m 2 For example, 5cm 3 / m 2 ~10cm 3 / m 2 It is more preferable that this is the case. The upper image in Figure 2B shows cells filled with ink. The volume density corresponds to the total volume of a particular surface area of ​​the anilox roller 10. The line count of the anilox roller is preferably less than 300 lines / cm (lpcm), and preferably less than 200 lines / cm, for example, 160 lpcm to 260 lpcm. The line count determines the pitch Pa of the anilox roller as follows: Pa = 10.000 / lpcm. The pitch Pa of the anilox roller is shown in Figure 2B. Figure 2C shows several possible anilox rollers that may be used in embodiments of the present invention. For example, the anilox roller may have a hexagonal cell pattern as in the first two images, or a square cell pattern as in the last image.

[0059] During the step of acquiring a raster image file, the first resolution R1 is preferably selected such that Pa is greater than 1.5*P1, and more preferably 2*P1 to 10*P1.

[0060] Figures 3 and 4 show two further exemplary embodiments for imaging a mask layer. The example is similar to the example in Figure 1, the difference being that the sampling pattern is superimposed on a halftone raster image file. This pattern can be added before (Figure 3) or during (Figure 4) imaging of the mask layer. The sampling pattern is preferably a repetition of blocks, each consisting of one or more imaged pixels and one or more unimaged pixels. In the example, the sampling pattern is a single-pixel checkerboard pattern, but the sampling pattern may be any of the following, or a combination thereof: a single-pixel checkerboard pattern, a single-pixel pattern such as a pattern where each imaged pixel is surrounded by eight unimaged pixels, a multiple-pixel pattern such as a multiple-pixel checkerboard pattern, a line pattern, a dash pattern, a circle pattern, a grid pattern.

[0061] Figure 6 shows another exemplary embodiment of a method for imaging a mask layer to obtain a relief plate for printing on a substrate. The method comprises the steps of: providing a mask layer; obtaining a halftone raster image file having imaged pixels and non-imaged pixels at a first resolution R1 (in the illustrated example, five of six pixels are shown as imaged pixels) (see step 1); improving the resolution of the halftone raster image file to obtain a high-resolution raster image file having high-resolution imaged pixels and high-resolution non-imaged pixels at a second resolution R2 higher than the first resolution R1 (see step 2); superimposing a sampling pattern having the same repetition period as the first resolution R1 onto the high-resolution raster image file so that only some of the high-resolution imaged pixels are imaged (see step 2); and imaging the mask layer according to the high-resolution raster image file having the superimposed sampling pattern (see step 3). Preferably, the second resolution R2 is a multiple of the first resolution R1. In Figure 6, two possible second resolutions R2 are shown, where R2 is four times R1 in the left example and R2 is three times R1 in the right example. This implies that in the left example, one pixel of resolution R1 is replaced by a 4x4 pixel of resolution R2. In this example, the superimposed sampling pattern consists of repeating 2x2 imaged pixel blocks surrounded by 12 non-imaged pixels. In the right example, one pixel of resolution R1 is replaced by a 3x3 pixel of resolution R2. In this example, the superimposed sampling pattern consists of repeating blocks of one imaged pixel surrounded by 8 non-imaged pixels.

[0062] The step of imaging the mask layer according to a high-resolution halftone raster image file (see step 3) is preferably performed such that the imaged spots have a maximum dimension D greater than the second pitch P2, and more preferably so that the maximum dimension D is greater than (√2 × P2), where the second pitch P2 corresponds to the second resolution R2. In the example on the left, this results in four overlapping spots for each imaged pixel of resolution R1. In the example on the right, this results in one large spot for each imaged pixel of resolution R1.

[0063] For the example in Figure 1, the method further includes the steps of preparing a relief plate using an imaged mask layer, transferring ink to the relief plate using an anilox roller, and transferring the ink from the relief plate to a substrate; see also the description of Figure 2A above. The volume density of the anilox roller is 5 cm³. 3 / m 2 It is preferable that it be greater than 7 cm 3 / m 2 The above is preferable, the number of lines per centimeter is less than 300, and preferably less than 200. The first resolution R1 is preferably selected such that the pitch Pa of the anilox roller is greater than 1.5*P1, and more preferably 2*P1 to 10*P1.

[0064] In the exemplary embodiments shown in Figures 1, 3, 4, and 6, a modified raster image file may be generated before imaging and based on the halftone raster image file to have at least 2 bits per pixel, where each of the at least 2 bits indicates whether the pixel is an unimaged pixel, an imaged pixel imaged with a first imaging setting, an imaged pixel imaged using a second imaging setting different from the first imaging setting, or optionally an imaged pixel imaged using a third imaging setting different from the first and second imaging settings, and imaging is performed based on the modified raster image file. The imaging setting may, for example, indicate the dimension D or shape of the spot to be imaged. By using such a modified raster image file, it becomes convenient to use different imaging settings for different parts of the image.

[0065] Figures 7A, 7B, and 7C show the results of printing on corrugated cardboard using the prior art method, the method according to Figure 1 (with R1 = 846 dpi), and the method according to Figure 3, respectively, using the same anilox roller with a screen ruling of 600 lines / inch or 236 lines / centimeter.

[0066] In the prior art embodiment shown in Figure 7A, a fairly high-resolution image (R1 = 2540 dpi) is used, and the unevenness of the corrugated cardboard is visible through the printed layer. In fact, a wavy structure is visible through the printed layer. This effect is called fluting. The printing results shown in Figures 7B and 7C are clearly improved, with no fluting visible or reduced fluting. When using a relatively low first resolution R1 instead of the high resolution used in the prior art, improvements in printing results can be obtained by combining it with a spot size that results in a finely raised surface structure on the dots. This is thought to be because the imaged spots do not completely overlap, and the fine raised areas of the corresponding relief plate are large enough to be covered by the ink from the anilox roller, effectively concealing the uneven structure of the substrate, at least to an appropriate extent. In this way, more ink is transferred to the rough substrate that covers the unevenness. Therefore, when printing grayscale, especially when printing grayscale images on substrates with uneven surfaces such as corrugated cardboard or wallpaper, image quality can be improved.

[0067] It should be further noted that by starting with a low-resolution raster image file with resolution R1 and then increasing the resolution to R2, problems such as interference / moire can be mitigated or avoided compared to starting with a high-resolution raster image file with resolution R2. This is illustrated in Figures 12A to 12C. Figure 12A shows the result of starting with a high-resolution file and imaging the pixels using a spot dimension D of 14 microns. This avoids the moire problem, but fluting may occur (see Figure 7A). Figure 12B shows the result of starting with a high-resolution file, then decreasing its resolution, and then using a spot dimension D of 14 microns. This mitigates the fluting problem, but moire occurs. Figure 12C shows an embodiment of the present invention that starts with a low-resolution raster image file having a resolution R1 of less than 2000 dpi, in this case 800 dpi. This implies that a non-raster image file, such as a pdf or ps file, is directly rasterized into a raster image file with resolution R1. Next, the pixels are imaged using a spot size D of 14 microns. This reduces both the moiré effect and the fluting effect problem; see also Figures 7B and 7C.

[0068] Figures 5A to 5E show further examples of how the shape and / or size of the image spots can be controlled. Figure 5A corresponds to what is shown in Figures 1, 3, and 4, where the diameter D of the spot is significantly less than P1. In the example of Figure 5B, D is equal to P1, so the imaged spots are in contact with each other, and in the example of Figure 5C, D is greater than P1, so the imaged spots overlap. In the example of Figure 5D, imaging is performed such that the dimensions and / or shape of the imaged spots are changed according to a regular or irregular pattern. Furthermore, as shown in Figure 5E, the positions of the imaged spots can also be changed relative to each other. All pixels in a row and / or column may be aligned as in Figures 5A to 2C, or some pixels may be offset from the center position as in Figure 5E.

[0069] The imaging is preferably carried out such that all imaged spots have substantially the same dimensions and / or shape, or such that the dimensions and / or shape of the imaged spots are modified according to a regular or irregular pattern. Furthermore, the dimensions and / or shape may be modified according to the grayscale value.

[0070] The imaging step preferably includes ablation of the mask layer, and more preferably includes ablation using a laser. Before or after imaging, the mask layer can usually be fixed and placed on the photopolymerizable layer of the relief precursor. The step of preparing a relief plate using the imaged mask layer generally includes exposing the photopolymerizable layer of the relief precursor through the mask layer and developing the relief precursor to obtain a relief plate.

[0071] Figure 8 shows a system for manufacturing a relief plate printing plate or sleeve from a relief precursor. The system comprises a control module 100, an imager 110, an exposure means 120, and a developing means 130. After the mask layer of the relief precursor is imaged by the imager 110 using a raster image file and / or imaging instructions generated by the control module 100, the precursor is exposed to electromagnetic radiation through the imaged mask layer in the exposure means 120, thereby curing a portion of the photosensitive layer 16. The electromagnetic radiation may have wavelengths in the range of 200 to 2000 nm, preferably ultraviolet (UV) radiation with wavelengths in the range of 200 to 450 nm.

[0072] Electromagnetic radiation alters the properties of the exposed portion of the photosensitive layer, and as a result, the unexposed portion of the photosensitive layer is removed by the developing means 130, forming a relief plate printing plate or sleeve. Development is preferably achieved by treatment with a liquid (solvent, water, or aqueous solution) or by thermal development, and the dissolved or softened material is removed.

[0073] Liquid treatment can be carried out by spraying the precursor with a liquid, brushing the precursor in a liquid, or scrubbing it. The properties of the liquid used depend on the properties of the precursor being used. If the layer to be removed is soluble, emulsifying, or dispersible in water or an aqueous solution, water or an aqueous solution may be used. If the layer is soluble, emulsifying, or dispersible in an organic solvent or a mixture, an organic solvent or a mixture may be used.

[0074] In thermal developing, a flexible plate fixed to a rotating drum may be used as the thermal developing means. The thermal developing means further comprises a component for heating at least one additional layer and a component for bringing the outer surface of the heated at least one additional layer into contact with an absorbent for absorbing the molten material. The heating component may include a heatable underlay and / or infrared lamp for the flexible plate placed on the at least one additional layer. The absorbent can be pressed against the surface of the at least one additional layer, for example, using an optionally heatable roll. The absorbent can be moved continuously over the surface of the flexible plate while the drum rotates, repeatedly removing the material from the at least one additional layer. In this way, the molten material is removed while the unmolten areas remain, forming a relief.

[0075] The relief plate printing plate or sleeve may be further processed and ultimately used as a printing plate. Optionally, the system may include a photo-finishing apparatus or any other post-exposure processing unit. Optionally, a controller may be provided to control various units of the imaging system. Optionally, one or more pre-processing modules, such as a raster image processing (RIP) module that converts image files, such as PDF files, into raster image processing files, may be provided upstream of the control module 100; see also Figure 9, described later.

[0076] Figure 9 shows an exemplary embodiment of a control module 100 located downstream of the raster image processing module 90. The raster image processing (RIP) module 90 converts a source image file, such as a pdf, ps, or xps file, into a halftone raster image file (also called a bitmap) having a first resolution R1. Raster image processing is the process of converting vector-based digital information, such as a PostScript file, into a high-resolution raster image file. Typically, the RIP module 90 is implemented as a software component of an operating system or as a firmware program executed on a microprocessor. The RIP module 90 may further have layout capabilities. If multiple small images need to be printed, these images may be grouped according to a printing pattern. This grouping can also be performed by the RIP module 90.

[0077] Figure 9 shows an embodiment of the control module 100 that can be used in combination with the embodiments according to the first aspect, for example, the embodiments in Figures 1, 3, and 4. The control module 100 is configured to receive a halftone raster image file having imaged pixels and non-imaged pixels at a first resolution R1, optionally apply a sampling pattern to the halftone raster image file, and control the imager 110 so that the imaged spots have a maximum dimension less than (√2*P1).

[0078] Figure 10 shows an alternative embodiment of the control module 100 that, in a second embodiment, can be used in combination with, for example, the embodiment in Figure 6. The image source file is a raster image processed in the RIP 90 to generate a halftone raster image file having a first resolution R1, for example, 800 dpi. In this example, it is assumed that grayscale areas need to be printed. The control module 100 is configured to increase the resolution to a second resolution R2 and superimpose a sampling pattern onto the high-resolution raster image file. The resulting raster image file is then sent to the imager 110 to perform imaging accordingly.

[0079] Figure 11 shows an imaged spot obtained from an exemplary embodiment of a method for imaging a mask layer. For illustrative purposes, portions of the halftone regions (10%, 30%, and 70%) are shown, but those skilled in the art will understand that any combination of halftone regions is possible. As shown, the diameters d1, d2, and d3 of the imaged spot 41 may vary depending on the size of the dots in each halftone region 34.

[0080] For example, for small tonal values, e.g., 0% to 10%, a first diameter d1 may be used so that touching or overlapping imaged spots 41 are acquired (see the upper image in Figure 11). For larger tonal values, e.g., 10% to 50%, a second diameter d2 smaller than d1 may be used so that the imaged spots 41 do not overlap, and for even larger tonal values, e.g., 50% to 99%, an even smaller diameter d3 may be used (see the middle and lower images in Figure 11). Alternatively, a sampling pattern may be used for even larger tonal values ​​in combination with a larger diameter.

[0081] Embodiments of the present invention are particularly useful in classical amplitude modulation (AM) screens, where the distance Dd between adjacent dots in a halftone region is the same even in halftone regions having different tonal values. The tonal values ​​of the halftone region are then determined by the size of the group of accumulated imaged pixels corresponding to the accumulated imaged spot 41, i.e., the size of the dots. However, those skilled in the art will understand that other embodiments of the present invention may be used for frequency modulation (FM) screens or AM and FM screens where the distance Dd is not constant.

[0082] Those skilled in the art will readily understand that the steps of the various methods described above can be performed by a programmed computer. In this specification, some embodiments also cover program storage devices, such as machine- or computer-readable digital data storage media, which encode programs of machine-executable or computer-executable instructions, which perform some or all of the steps of the methods described above. Program storage devices may be, for example, digital memory, magnetic storage media such as magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. These embodiments also cover computers programmed to perform the steps of the methods described above.

[0083] Although the principles of the present invention have been shown above in relation to specific embodiments, it should be understood that this description is merely illustrative and does not limit the scope of protection as defined by the appended claims.

Claims

1. A method for preparing a relief plate and printing on a substrate, particularly an uneven substrate such as corrugated cardboard, using the relief plate, The steps include providing a mask layer and A step of acquiring a halftone raster image file having image pixels and non-image pixels at a first resolution R1, wherein the first pitch P1 corresponds to the first resolution R1. The steps include: imaging the mask layer according to the halftone raster image file such that the imaged spot has a maximum dimension (D) smaller than (√2 * P1), preferably smaller than P1; The steps include preparing a relief plate using the imaged mask layer, The steps include transferring ink to the relief plate using an anilox roller, The steps include transferring the ink from the relief plate to the substrate and Includes, The first resolution R1 is less than 2000 dpi, preferably less than 1700 dpi, and more preferably less than 1500 dpi. The volume density of the aforementioned anilox roller is 5 cm³ ３ / m ２ The above is preferable, and preferably 7 cm ３ / m ２ That is the method.

2. The method according to claim 1, wherein the number of wires in the anilox roller is less than 300 wires per centimeter, preferably less than 200 wires per centimeter.

3. The method according to claim 2, wherein the number of lines corresponds to the anilox pitch Pa, and during the steps of acquisition, the first resolution R1 is selected such that Pa is greater than 1.5 * P1, preferably Pa is in the range between 2 * P1 and 10 * P1.

4. The method according to any one of claims 1 to 3, wherein the sampling pattern is superimposed on the halftone raster image file before the step of imaging the mask layer, or during the execution of the step of imaging.

5. The method according to claim 4, wherein the sampling pattern is a repetition of blocks in which one or more image pixels and one or more non-image pixels are combined.

6. The aforementioned sampling pattern is A single pixel pattern such as a single pixel checkerboard pattern or a pattern in which each imaged pixel is surrounded by eight non-imaged pixels. Multiple pixel patterns, such as a checkerboard pattern of multiple pixels, Line patterns, Dash pattern, Circle patterns, and, Grid pattern, The method according to claim 4 or 5, wherein any one of the above, or a combination thereof.

7. Before image conversion, a modified raster image file is generated based on the aforementioned halftone raster image file, so that it has at least 2 bits per pixel. The aforementioned at least two bits, for each pixel, Non-image pixels, The pixels to be imaged in the first image setting, Image pixels, and, which are imaged using a second image setting different from the first image setting described above, Furthermore, optionally, a third imaging setting different from the first and second imaging settings described above is used to image the pixels, Indicates whether it is one of the following: The method according to any one of claims 1 to 6, wherein the imaging step is performed based on the modified raster image file.

8. The method according to any one of claims 1 to 7, wherein the anilox roller has a hexagonal cell pattern.

9. The method according to any one of claims 1 to 8, wherein the first resolution R1 is 700 to 1500 dpi.

10. A method for imaging a mask layer to obtain a relief plate for printing on a substrate, The steps include providing a mask layer and The steps include obtaining a halftone raster image file comprising image pixels and non-image pixels at a first resolution R1, The steps include improving the resolution of the halftone raster image file to obtain a high-resolution raster image file having high-resolution image pixels and high-resolution non-image pixels at a second resolution R2 that is higher than the first resolution R1, The steps include superimposing a sampling pattern having a repetition period equal to the first resolution R1 onto the high-resolution raster image file so that only a portion of the high-resolution image pixels are imaged, The steps of imaging the mask layer according to the high-resolution raster image file having the superimposed sampling pattern and Methods that include...

11. The method according to claim 10, wherein the second resolution R2 is a multiple of the first resolution R1.

12. The method according to claim 10 or 11, wherein the second resolution R2 is at least four times the first resolution R1.

13. The method according to any one of claims 10 to 12, wherein the second pitch P2 corresponds to the second resolution R2, and the step of imaging the mask layer according to a high-resolution halftone raster image file is performed such that the imaged spots have a maximum dimension (D) greater than P2, and more preferably so that they have a maximum dimension (D) greater than (√2 * P2).

14. The method according to any one of claims 10 to 13, wherein the sampling pattern is a repetition of blocks in which one or more image pixels and one or more non-image pixels are combined.

15. The method according to any one of claims 10 to 14, wherein R2 is at least three times R1, and the sampling pattern is formed by repeating blocks of one or more adjacent image pixels surrounded by at least eight non-image pixels.

16. Based on the high-resolution raster image file having the sampling pattern superimposed before imaging, a modified high-resolution raster image file is generated that has at least 2 bits per pixel. The aforementioned at least two bits, for each pixel, Non-image pixels, The pixels to be imaged in the first image setting, Image pixels, and, which are imaged using a second image setting different from the first image setting described above, Furthermore, optionally, a third imaging setting different from the first and second imaging settings described above is used to image the pixels, Indicates whether it is one of the following: The method according to any one of claims 10 to 15, wherein the imaging step is performed based on the modified raster image file.

17. The steps include preparing a relief plate using the imaged mask layer, The steps include transferring ink to the relief plate using an anilox roller having a resolution Ra, The steps include transferring the ink from the relief plate to the substrate and The method according to any one of claims 10 to 16, further comprising:

18. The volume density of the aforementioned anilox roller is 5 cm³ ３ / m ２ The above is preferable, and preferably 7 cm ３ / m ２ The method according to claim 17.

19. The method according to claim 17 or 18, wherein the number of wires in the anilox roller is less than 300 wires per centimeter, preferably less than 200 wires per centimeter.

20. The method according to claim 19, wherein the number of lines corresponds to the anilox pitch Pa, and during the steps of acquisition, the first resolution R1 is selected such that Pa is greater than 1.5 * P1, preferably Pa is in the range between 2 * P1 and 10 * P1.

21. The method according to any one of claims 1 to 20, wherein the step of obtaining a halftone raster image file is the result of raster image processing of a non-raster image file, such as a PDF file or a PS file, in order to directly obtain the halftone raster image file having the first resolution R1.

22. The method according to any one of claims 1 to 21, wherein the imaging step is performed such that all the imagesed spots have substantially the same dimensions and / or shape, or such that the dimensions and / or shape of the imagesed spots are altered according to a regular or irregular pattern.

23. The method according to any one of claims 1 to 22, wherein the imaging step preferably includes ablation of the mask layer, and more preferably includes ablation using a laser.

24. The aforementioned method, A step of providing the mask layer on the photopolymerizable layer of the relief precursor before or after the imaging step, The method according to any one of claims 1 to 23, further comprising:

25. The method according to claim 24, wherein the step of preparing the relief plate using the imaged mask layer comprises exposing the photopolymerizable layer of the relief precursor through the mask layer and developing the relief precursor to obtain the relief plate.

26. A relief plate obtained by the method described in any one of claims 1 to 25.

27. A computer program, a computer program product, or digital storage means, wherein the computer program comprises computer-executable instructions for controlling the method according to any one of claims 1 to 25 when the computer program is executed on a computer.

28. A system for processing a relief precursor, comprising: an imager configured to image a mask layer; an exposure means configured to expose the relief precursor through the imaged mask layer; a developing means configured to remove at least a portion of unexposed material from the relief precursor; and a control module for controlling the imager according to the method of any one of claims 1 to 25.

29. The volume density is 5 cm ３ / m ２ or more, and preferably 7 cm ３ / m ２ or more, and / or the number of lines is less than 300 lines per centimeter, preferably less than 200 lines per centimeter, and further comprising an anilox roller, the system according to claim 28.

Images