Print method, printer and software product

Abstract

The present invention relates to a print method for printing multilayer prints, wherein an intermediate layer is provided between a first and a third layer. The present invention further relates to a printer suitable for performing such a method. The present invention further relates to a software product.

Description

[0001] The present invention relates to a print method and a printer suitable for performing such a method. The present invention further relates to a software product.BACKGROUND OF THE INVENTION

[0002] Multilayer prints, are print wherein an image or object is built by depositing a plurality of ink layers on a recording medium or a support medium. Non-limiting examples of multilayer prints include: Day& night prints: prints having two colored layers separated by a white ink layer in between the two colored layers; 2.5 D or 3D prints, wherein an object is printed having a certain height, wherein the object is printed by applying a plurality of layers.

[0003] When making prints consisting of multiple layers, the adhesion between layers may be insufficient. When adhesion between layers is insufficient, this may result that the print or printed object can be easily damaged via transport and / or the end-user after printing (e.g. when scratching on prints, or when bending prints), which is undesired.

[0004] Therefore a need exists for having a printer and a corresponding method of printing that is capable of making prints having improved adhesion.

[0005] It is therefore an object of the present invention to provide a print method that results in multi-layer prints showing improved adhesion.

[0006] It is another object of the present invention to provide an printing apparatus suitable for performing such a method.SUMMARY OF THE INVENTION

[0007] The object of the invention is achieved in a print method for printing a multilayer print, the method comprising the steps of: a) printing a first layer by depositing a first ink in a first number of passes; b) printing an intermediate layer by applying a second ink in a second number of passes; c) printing a third layer by depositing a first ink in a third number of passes.

[0008] The method may be performed using a printer. A printer is also referred to as printing apparatus. The printer may be configured to in printing operation apply an inkjet ink onto a recording medium or a support medium. The inkjet ink may be a suitable type of ink, such as a phase change ink and / or radiation-curable in, such as a radiation-curable gelling ink.

[0009] The printer may further comprise a medium support. The medium support may be configured to in operation support the recording medium. Optionally, the recording medium may be moved in a medium transport direction. The medium support may comprise a flat table. Optionally, the medium support may comprise an endless belt. The medium support may comprise holes for applying an underpressure. Applying an underpressure may fix the recording medium to the medium support.

[0010] Optionally, the printer may comprise medium transport unit. The medium transport unit may be configured to in operation move the recording medium relative to the printer in the medium transport direction.

[0011] In the method according to the present invention, an image or object is built up in a plurality of layers. A layer may be a part of the image or object to be formed. Optionally, each individual layer may have certain properties different from another layer. For example, in day & night applications, a first layer may form a first colored image, a second layer may form a white layer separating the first and third layer and the third layer may form a second colored image. When printing 2.5D or 3D prints, after each layer the print gap, i.e. the distance in z-direction between the print heads and the recording medium or support medium, may be increased, to prevent the object being printed from touching the print heads.

[0012] Each layer may be printed in a plurality of passes. The number of passes may be the same for the plurality of layers or may be different. A pass is a movement of a print head in a scanning direction while depositing ink. A pass may also be referred to as a swath.

[0013] In the method according to the present invention, in step a), a first layer is printed by depositing a first ink in a first number of passes. The first layer may preferably be printed on a recording medium or a support medium. Alternatively, the first layer may be printed onto a previously printed image.

[0014] The first layer may be formed by depositing a first ink. The first ink may be a colorless ink. Alternatively, the first ink may be an ink set comprising a set of colored inks, for example a cyan, magenta, yellow and black ink set, or a cyan, magenta, yellow, black, orange, violet and green ink set. The first layer is printed in a first number of passes.

[0015] Preferably, the first number of passes may be in the rage of 4-32, preferably in the range of 8-24.

[0016] In the method according to the present invention, in step b), an intermediate layer is printed by depositing a second ink in a second number of passes.

[0017] The intermediate layer may be formed by depositing a second ink. The second ink may be a white ink. Alternatively, the second ink may be a colored ink, for example a cyan, magenta, yellow or black ink. The intermediate layer is printed in a second number of passes. Preferably, the second number of passes may be in the rage of 1-20, preferably in the rage of 2-8. Preferably, the intermediate layer may be printed on top of the first layer.

[0018] In the method according to the present invention, in step c), a third layer is printed by depositing a first ink in a third number of passes.

[0019] The third layer may be formed by depositing a first ink. The third layer is printed in a third number of passes. Preferably, the third number of passes may be in the rage of 4-32, preferably in the rage of 8-24. Preferably, the third layer may be printed on top of the intermediate layer.

[0020] Optionally, more than three layers may be provided. Optionally, a fifth, seventh, etc layer may also be provided. Preferably, between the third and the fifth layer, an intermediate layer is provided. If a seventh layer is printed, then preferably an intermediate layer may be provided between the fifth and seventh layer. The intermediate layers may be printed in a lower number of passes than the fifth, seventh, etc, layer.

[0021] In an embodiment, the first ink is a colorless ink, and the second ink is an ink comprising a colorant.

[0022] Colorless inks may be suitably used for example when printing 2.5D or 3D objects. Colorless inks may not comprise a colorant. The second ink may be a colored ink, i.e. an ink comprising a colorant. Examples of an ink comprising a colorant are black inks, cyan inks, magenta inks and yellow inks. The colored ink may be for example a magenta ink.

[0023] In an embodiment, the first ink and the second ink are radiation-curable inks, and wherein the inks are cured by irradiation.

[0024] Radiation-curable inks are inks that comprise one or more components that may react (e.g. polymerize) under influence of suitable radiation, such as electromagnetic radiation, e.g. ultraviolet (UV) radiation. Examples of radiation-curable components are epoxides and (meth)acrylates. (Meth-)acrylates may comprise one or more reactive groups for forming an acrylate polymer. The radiation-curable ink may comprise one type of radiation curable compound or alternatively, the radiation-curable medium may comprise a mixture of radiation-curable compounds.

[0025] Upon irradiating the radiation-curable ink with a suitable type of radiation, the ink may be cured. When curing the inks, a polymerization reaction occurs in the ink, thereby forming a molecular network that provides a robust print.

[0026] The printer may preferably be provided with a curing unit for curing the ink. The curing unit may comprise one or more sources of radiation. Non-limiting examples of a sources of radiation include a halogen lamp, a mercury lamp and / or a LED lamp. Optionally, a plurality of sources of radiation may be used to irradiate the inkjet ink composition. The curing unit may be a page-wide curing unit. Alternatively, the curing unit may be a scanning curing unit.

[0027] In a further embodiment, the first ink and the second ink are UV gelling inks. UV gelling inks are UV-curable ink that are fluid at elevated temperatures and form a gel at lower temperatures. Typically, the gelling properties are provided to the ink by a gelling agents. Gellings agents are also referred to as gellants or thickeners.

[0028] UV gelling inks can be jetted at elevated temperatures. After being deposited, the ink droplets cool down and turn to a gelled state. In the gelled state, the ink droplets are highly viscous and will hardly flow. Hence, it is not necessary to immediate cure the ink droplets after being deposited.

[0029] In an embodiment, the first number of passes is greater than the second number of passes. The ratio between the first number of passes and the second number of passes may be in the range of from 1:4 to 1:40.

[0030] The intermediate layer may hence be printed in a smaller number of passes than the first layer. The intermediate layer may have a smaller thickness than the first layer.

[0031] In an embodiment, the third number of passes is greater than the second number of passes. The ratio between the third number of passes and the second number of passes may be in the range of from 1:4 to 1:40.

[0032] The intermediate layer may hence be printed in a smaller number of passes than the third layer. The intermediate layer may have a smaller thickness than the third layer.

[0033] In an embodiment, the first number of passes is equal to the third number of passes. The first layer and the third layer may have the same thickness.

[0034] In an embodiment, the first layer is depositing in a plurality of sublayers, wherein the upper sublayer of the first layer is printed simultaneously with the intermediate layer. The first layer may be deposited in a plurality of sub layer, comprising at least a first sublayer and a second sub layer. Optionally, the first layer may comprise more than two sublayers. Each sublayer may be deposited in a number of passes, wherein the sum of the passes in which the sublayers are provided equals the first number of passes. For example, a first sublayer may be provided in 3 to 30 passes, preferably in the range of 6 to 20. The second sublayer may be provided for example in 1 to12 passes, preferably from 2 to 8 passes.

[0035] The first sublayer may be deposited first. The second sublayer may be deposited on top of the first sublayer. In case there is a third sublayer, the third sublayer may be positioned on top of the second sublayer, etc.

[0036] In case there are two sublayers, the second sublayer is the upper sublayer. In case there are three sublayers, the third sublayer may be the upper sublayer, etc. The upper sublayer of the first layer is printed simultaneously with the intermediate layer. Hence, the first ink and the second ink may be deposited simultaneously. Hence, the upper sublayer and the intermediate layer may be mixed. This may increase the adhesion between the first layer and the intermediate layer.

[0037] Optionally, the third layer may also be deposited in a number of layers. The third layer may be deposited in a plurality of sub layer, comprising at least a first sublayer and a second sub layer. Optionally, the third layer may comprise more than two sublayers. Each sublayer may be deposited in a number of passes, wherein the sum of the passes in which the sublayers are provided equals the first number of passes. For example, a first sublayer may be provided in 3 to 30 passes, preferably in the range of 6 to 20. The second sublayer may be provided for example in 1 to12 passes, preferably from 2 to 8 passes.

[0038] The first sublayer may be deposited first. The second sublayer may be deposited on top of the first sublayer. In case there is a third sublayer, the third sublayer may be positioned on top of the second sublayer, etc.

[0039] The bottom sublayer of the third layer may be deposited simultaneously with the intermediate layer.

[0040] The upper sublayer of the third layer may be deposited simultaneously with a second intermediate layer.

[0041] Preferably, in case the first, third, etc layer is deposited in a plurality of sub layers, then each one of the first, third, etc layers comprises at least one sublayer that is not deposited simultaneously with an intermediate layer.

[0042] Preferably, the sublayers of the first, third, etc layer printed simultaneously with the intermediate layer are deposited in one or two passes.

[0043] In an embodiment, the method according to the present invention may be performed in a flatbed printer.

[0044] In an embodiment, the method according to the present invention may be performed in a scanning printer having a width of at least 1.0 m.

[0045] In an aspect of the invention, a printer is provided, the printer comprising: a. a first ink applicator for applying a first ink composition; b. a second ink applicator for applying a second ink composition; c. optionally comprising a curing unit; and d. a controller configured to control the printing apparatus to perform a method according to the present invention.

[0046] A printer is also referred to as printing apparatus. The printer may be configured to in printing operation apply an ink.

[0047] The printer comprises a first ink applicator. The ink applicator may be configured to in operation apply a predetermined pattern of the first ink. The printer further comprises a second ink applicator. The ink applicator may be configured to in operation apply a predetermined pattern of the second ink.

[0048] The ink applicator may comprise at least one inkjet print head configured to in operation jet ink onto the recording medium. The print head may be for example a thermal inkjet print head or a piezo electric inkjet print head. The printer may comprise a plurality of inkjet print heads. The print unit may be a page-wide print unit or may be a scanning print unit. A scanning print unit may be configured to in operation move in reciprocation in a scanning direction. The scanning direction may be perpendicular to a medium transport direction.

[0049] The printer may optionally comprise a media support. The media support may be configured to in operation support the recording medium. Optionally, the recording medium may be moved in a medium transport direction. The medium support may comprise a flat table. Optionally, the medium support may comprise an endless belt. The medium support may comprise holes for applying an underpressure. Applying an underpressure may fix the recording medium to the medium support.

[0050] Optionally, the printing apparatus may comprise a medium transport unit. The medium transport unit may be configured to in operation move the recording medium relative to the printer in the medium transport direction.

[0051] The printer may further optionally comprise a curing unit. The curing unit may cure the ink in case radiation-curable ink is used. The curing unit is configured to in operation irradiate a recording medium provided with a radiation-curable ink. By irradiating the radiation-curable ink, a chemical reaction may occur in the radiation-curable ink, which may result in curing or pre-curing of the fluid. The curing unit may be a scanning curing unit. Alternatively, the curing unit may be a page-wide curing unit.

[0052] The printer further comprises a controller. The controller may control the printer to perform a method in accordance with the present invention.

[0053] In an embodiment, the printer is a scanning printer having a width of at least 1 meter. In a scanning printer, a print unit may move in reciprocation in a main scanning direction, while depositing ink. In scanning printer having a width of at least 1.0 m, the time between a first passage of the print unit and a second passage of the print unit may take a relatively long time. This may increase the change of print artefacts. In printers wherein the chances of print artefacts occurring is increased, it is advantageous to use the method according to the present invention, which results in prints showing approved adhesion.

[0054] In a further embodiment, the printer is a flat bed printer.

[0055] A flatbed printer is a printer having a table configured to support. The table may be flat. The flatbed printer may comprise one or more print units that may be moved wrt the table in a main scanning direction as well as a sub-scanning direction. Flatbed table are suitable for making 2.5 D prints and / or 3D prints.

[0056] In a further aspect of the invention, a software product is provided, the software product comprising program code on a non-transitory machine-readable medium, wherein the program code, when loaded into a controller of a printing apparatus with at least one printing unit for depositing a radiation-curable fluid, a page-wide curing array and a control unit, causes the controller to perform a method according to the present invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: Fig. 1 is a schematic perspective view of a first example of a print system in accordance with the present invention in a first printing mode; Fig. 2A-2C show a schematic representation of a first example of a print method according to the present invention; Fig. 3A-3C show a schematic representation of a second example of a print method according to the present invention.

[0058] In the drawings, same reference numerals refer to same elements.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals have been used to identify the same or similar elements throughout the several views.

[0060] Fig. 1 shows a print system 11 comprising a number of workstations 8B and 8C, which may be personal computers or other devices for preparing colour image data for three dimensional objects to be printed. These workstations have access to a network N for transferring the colour image data to a print controller 8A that is configured to receive print jobs for three-dimensional objects consisting of voxels and derive pass images for each pass of the print engine 2 over the flat bed 1. The print system further comprises printer 5. The printer 5 comprises the print carriage 2 for applying colorants. In this embodiment, the print carriage comprises 5 print heads, each print head configured to deposit ink of a specific type or color; colored inks cyan (C), magenta (M), yellow (Y), black (K) and white (W) ink, and a colorless ink (CL), to a flat print medium 9, the substrate, in order to obtain a printed object. In this embodiment a UV-gelling ink is applied by print heads that reciprocally scan the substrate in a movement direction X perpendicular to a transport direction Y by means of a gantry 7. The marking material solidifies upon cooling after printing on the substrate. The invention is applicable using UV-curable marking materials that solidify after exposure to UV-light and other types of marking material that are printed in a layer with some thickness on a substrate.

[0061] The print carriage may further comprise two UV lamps (not shown), the print heads being positioned in between the print heads. The UV lamps may emit UV radiation for curing the UV gelling ink. In an embodiment, the printer may comprise addition curing lamps not positioned on the print head carriage. The additional curing lamps may be e.g. a scanning curing lamps, configured to move in reciprocation in the main scanning direction X, or a page-wide curing lamp.

[0062] Preferentially the distance between the flat substrate and the print elements that are used to apply the various colorants, is variable. This distance may be varied in order to keep the upper surface of the object within the latitude of the print elements. The latitude of the distance between a substrate of the scanning print head in print engine 2 is in the range of about 0.5 to 2 mm.

[0063] The printer comprises a user interface (not shown), which is placed on the print engine, but which may also be part of the printer controller 8A, for selecting a print job and optionally adapt a print job parameter, such as an absolute height parameter for indicating a maximum height of the object to be printed. A maximum number of voxels in the height direction perpendicular to the substrate may be used as height parameter. A user interface may be provided as a network site that is accessible with a browser on a client computer.

[0064] After sending a print job comprising image data from a workstation to the printer controller, the print job will be made visible on the user interface. It may be scheduled for further processing after selection from a list of print jobs or, alternatively, if the print job is on top of the list of print jobs. The print job comprises parameter values that determine the way the image data are to be printed, such as the way how the image data are to be converted into print data.

[0065] Fig. 2A-2C show a schematic representation of a first example of a print method according to the present invention.

[0066] In Fig. 2A, a recording medium 9 is shown. On recording medium 9, a first layer of ink 21 is deposited. The first ink layer 21 is deposited using a printer (not shown), for example a printer as shown In Fig. 1. The first layer 21 is deposited on the recording medium in 20 passes.

[0067] In Fig. 2B, a recording medium 9 is shown as well as a first layer 21 deposited on top of the recording medium. Further, an intermediate layer 22 is deposited on top of the first layer 21. The intermediate layer 22 is deposited using a printer (not shown), for example a printer as shown In Fig. 1. The intermediate layer 22 is deposited in 2 passes.

[0068] In Fig. 2C, a recording medium 9 is shown, as well as a first layer 21 deposited on the recording medium and an intermediate layer 22, deposited on the first layer 21. Further, a third layer 23 is deposited on top of the intermediate layer 22. The third ink layer 23 is deposited using a printer (not shown), for example a printer as shown In Fig. 1. The third layer 23 is deposited in 20 passes.

[0069] Fig. 3A-3C show a schematic representation of a second example of a print method according to the present invention.

[0070] In Fig. 3A, a recording medium 9 is shown. On recording medium 9, a first sublayer of ink 21a is deposited. The first sublayer 21a is deposited using a printer (not shown), for example a printer as shown In Fig. 1. The first sublayer 21a is deposited on the recording medium in 16 passes.

[0071] In Fig. 2B, a recording medium 9 is shown as well as a first sublayer 21a deposited on top of the recoding medium. Further, a second sublayer 21b of the first layer 21 and an intermediate layer 22 are deposited on top of the first sub layer 21a. The intermediate layer 22 and a second sublayer 21b of the first layer 21 are deposited using a printer (not shown), for example a printer as shown In Fig. 1. The intermediate layer 22 and a second sublayer 21b of the first layer 21 are deposited in 4 passes.

[0072] In Fig. 2C, a recording medium 9 is shown, as well as a first layer 21 and an intermediate layer 22. Further, an third layer 23 is deposited on top of the intermediate layer 22 and the second sublayer 21b of the first layer 21. The third ink layer 23 is deposited using a printer (not shown), for example a printer as shown In Fig. 1. The third layer 23 is deposited on the recording medium in 20 passes.

[0073] Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually and appropriately detailed structure. In particular, features presented and described in separate dependent claims may be applied in combination and any combination of such claims are herewith disclosed. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and / or having, as used herein, are defined as comprising (i.e., open language). The term coupled, as used herein, is defined as connected, although not necessarily directly.

Claims

1. Print method for printing a multilayer print, the method comprising the steps of: a) printing a first layer by depositing a first ink in a first number of passes; b) printing an intermediate layer by applying a second ink in a second number of passes; c) printing a third layer by depositing a first ink in a third number of passes.

2. Print method according to claim 1, wherein the first ink is a colorless ink, and wherein the second ink is an ink comprising a colorant.

3. Print method according to any of the preceding claims, wherein the first ink and the second ink are radiation-curable inks, and wherein the inks are cured by irradiation.

4. Print method according to claim 3, wherein the first ink and the second ink are UV gelling inks.

5. Print method according to any of the preceding claims, wherein the first number of passes is greater than the second number of passes.

6. Print method according to any of the preceding claims, wherein the third number of passes is greater than the second number of passes.

7. Print method according to any of the preceding claims, wherein the first number of passes is equal to the third number of passes.

8. Print method according to any of the preceding claims, wherein the first layer is depositing in a plurality of sublayers wherein the upper sublayer of the first layer is printed simultaneously with the intermediate layer.

9. Printer, the printer comprising: a. a first ink applicator for applying a first ink composition; b. a second ink applicator for applying a second ink composition; c. optionally comprising a curing unit; and d. a controller configured to control the printing apparatus to perform a method according to any of the claims 1-8.

10. Printer according to claim 9, wherein the printer is a scanning printer having a width of at least 1 meter.

11. Printer according to claim 10, wherein the printer is a flat bed printer.

12. A software product comprising program code on a non-transitory machine-readable medium, wherein the program code, when loaded into a controller of a printing apparatus with at least one printing unit for depositing a radiation-curable fluid and a second ink applicator for applying a second ink composition, causes the controller to perform a method according to any of the claims 1-8.

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