Printer and method for printing

Abstract

The present invention relates to a printer, the printer comprising a recording medium support for supporting a recording medium, the recording medium support having an upper surface, the upper surface of the recording medium support comprising a black anodized metal.. The present invention further relates to a method for printing using said printer.

Description

[0001] The present invention relates to a printer. The present invention further relates to a method for printing.BACKGROUND OF THE INVENTION

[0002] Printers are known in the art. There are several types of printers, including toner printers and inkjet printers. Inkjet printers are printers that are capable of forming an image onto a recording medium by applying a predetermined pattern of ink onto the recording medium. Preferably, several colors of ink may be used to form a multi-colored image. Several types of ink are known, including aqueous ink and radiation-curable inks. Using radiation-curable inks is advantageous, as these inks may form robust images. UV-curable inks are an example of radiation-curable inks.

[0003] UV-curable inks need to be cured in order to turn the ink applied onto the recording medium into a robust layer. Curing of UV-curable ink can be done by irradiating the ink with UV radiation. Typically, a printer using UV-curable ink is provided with at least one curing unit. The at least one curing unit may be configured to emit UV -radiation onto the recording medium to cure the ink. Examples of curing units are UV-LEDS, UV arc lamps, mercury vapor lamps and metal halide bulbs.

[0004] In operation, the UV-radiation emitted by the curing units may be reflected. In case the UV-radiation is reflected towards the print heads, then the ink in the nozzles may cure, which is unwanted, since cured ink can hardly be ejected from the print heads. It is therefore desired to reduce reflection of UV-radiation within the printer.

[0005] It is therefore an object of the invention to provide a printer, in which reflection of UV-radiation towards the print heads is prevented. It is a further object of the invention to provide a corresponding print method.SUMMARY OF THE INVENTION

[0006] The object of the invention is achieved in a printer, the printer comprising: at least one print unit for ejecting a radiation-curable ink; at least one curing unit; and a recording medium support for supporting a recording medium, the recording medium support having an upper surface, the upper surface of the recording medium support comprising a black anodized metal.

[0007] A printer is also referred to as printing apparatus or printing device. The printer may be configured to in printing operation apply a UV-curable ink. The UV-curable ink may be a UV-curable inkjet ink. Suitable types of radiation-curable inkjet inks including UV-curable inkjet inks are known in the art. Preferably, the printer may be an inkjet printer, configured to apply ink onto the recording medium by jetting droplets of ink onto the recording medium in a predetermined pattern to form an image.

[0008] The printer comprises a print unit. The print unit may be configured to in operation eject a radiation-curable ink. By depositing a predetermined pattern of a UV-curable ink on a recording medium, an image may be formed on the recording medium.

[0009] The print unit may comprise at least one inkjet print head configured to in operation eject ink onto the recording medium. The print head may be for example a thermal inkjet print head or a piezo electric inkjet print head. Optionally, the printer may comprise a plurality of inkjet print heads. One type or color of ink may be used to form the image, but alternatively more than one type and / or color of ink may be used. A Cyan, a Magenta, a Yellow and a blacK ink may be used to form the image. In addition, one or more of a white ink, brown ink, grey ink, light magenta, light cyan, red, green, orange, purple ink may be used. Further, one or more of a primer composition, an overcoat composition and a metallic ink may be used. 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. The medium transport direction may be a direction in which the recording medium moves relative to the print unit. The recording medium may be moved. Alternatively, the print unit may be moved with regard to the recording medium. In that case, the print unit may be configured to move with respect to the recording medium both in reciprocation in the scanning direction and additionally, to move with respect to the recording medium in the medium transport direction, perpendicular to the scanning direction.

[0010] The printing apparatus further comprises a curing unit. The curing unit is configured to in operation irradiate a recording medium provided with a UV-curable ink. By irradiating the UV-curable ink, a chemical reaction may occur in the UV-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. The page-wide array may extend in a first direction, the first direction being substantially perpendicular to a direction of relative recording medium transport. The recording medium may move with respect to the scanning print unit. The relative movement may be effected by moving at least one of the recording medium and print unit. The direction of relative movement of the print unit and the recording medium is the relative recording medium transport direction.

[0011] The printing apparatus may further comprise a medium support. The medium support may be configured to in operation support the recording medium. A recording medium may also be referred to as substrate. Optionally, the recording medium may be moved in a medium transport direction. The medium support may comprise a flat table. The medium support may comprise holes for applying an underpressure. Applying an underpressure may fix the recording medium to the medium support.

[0012] Optionally, the printing apparatus 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.

[0013] In the printer according to the present invention, the recording medium support has an upper surface, the upper surface of the recording medium comprising a black anodized metal.

[0014] The upper surface of the recording medium support may be a surface, which in printing operation, is in direct contact with the recording medium.

[0015] A black anodized metal may absorb UV-radiation. Hence, the recording medium support having an upper surface comprising a black anodized metal may reflect less UV-radiation in printing operation than other materials. As the upper surface of the recording medium support may reflect less UV-radiation, the at least one print unit may receive less UV-radiation, which may result in less nozzle clogging and / or other problems caused by unwanted curing of the ink in and / or around the print units.

[0016] Examples of black anodized metals are black anodized aluminum, black anodized magnesium and black anodized titanium. Black anodized aluminum is preferred. Black anodized metals are black and capable of absorbing radiation, including UV-radiation. By having a recording medium support, of which the upper surface comprise a black anodized metal, such as black anodized aluminum, reflection of UV-radiation towards the print units can be prevented, thereby preventing unwanted curing of ink in and around the nozzles of the print units.

[0017] In an embodiment, the printer further comprises a print carriage, the print carriage carrying the at least one print head.

[0018] The print carriage may be configured to carry at least one print unit. In case the print carriage carries a plurality of print units, the print units may be arranged on the print head carriage in one or more rows.

[0019] The print head carriage may be configured to, in printing operation, move in reciprocation in a main scanning direction. When moving in reciprocation, the relative position of the print head carriage and the recording medium support may change. Because the upper surface of the recording medium support absorbs at least part of the UV radiation emitted during printing, the print units may receive no or little UV-radiation during printing.

[0020] In a further embodiment, the print carriage further carries the at least one curing unit. The at least one curing unit may be arranged on the print head carriage. Optionally, the print head carriage may carry more than one curing unit. The at least one curing unit may preferably be arranged at a lateral side, in the sub scanning direction, of the print carriage.

[0021] In an embodiment, the printer is selected from a flatbed printer or a hybrid printer.

[0022] A flatbed printer is a printer comprising a table on which a recording medium can be positioned. The table is a flat surface. The upper surface of the table may comprise a black anodized metal. One or more pieces of recording medium can be positioned on the table. After printing, the one or more recording media may be removed from the table. This may be done manually, using machines and / or in an automated manner. Typically, during printing , the position of the recording medium with regard to the recording medium support is fixed. The print unit and the recording medium support may move with respect to one another, however. Flatbed printers are suited for printing on a large variety of media, including objects such as doors, glass panels and / or metal panels.

[0023] A hybrid printer is a printer that is capable of handling both rigid media and flexible substrates, such as web-based media. The hybrid printer may also comprise a recording medium support having a relatively large, flat surface. The upper surface of the recording medium support may comprise a black anodized metal.

[0024] In an embodiment, the recording medium support is provided with a plurality of suction holes.

[0025] The plurality of suction holes may be connected to a vacuum source for creating a reduced pressure. The reduced pressure may prevent a recording medium positioned on the recording medium support from moving.

[0026] The plurality of suction holes may be controlled together. Alternatively, the plurality of suction holes may be divided over two or more vacuum zones, which can be controlled independently.

[0027] In an aspect of the invention, a method for printing is provided, the method comprising the steps of: providing a recording medium; applying an image onto the recording medium using a printer according to the present invention.

[0028] In the method in accordance with the present invention, a recording medium is provided. The recording medium may be selected for example from paper, foil, textile, corrugated media or rigids. Examples of rigids include panels, for example panels for doors or walls, glass panels, polymeric panels, metallic panels or panels of a composite material. In a further step, an image is applied onto the recording medium using a printer according to the present invention.

[0029] In an embodiment, the recording medium is a transparent recording medium having a thickness of at least 5 mm.

[0030] When using thick, transparent media, UV radiation may be reflected by the recording medium. In a preferred embodiment, the thickness of the medium is at least 5 mm. When using a thick transparent substrate in a printer, which is not provided with a recording medium support for supporting a recording medium, the recording medium having an upper surface, the upper surface of the recording medium support comprising a black anodized metal, then the resulting gap between the curing lamp and the upper surface of the recording medium support may make the reflectance angles towards the printheads increasingly favourable and too much UV stray-light is cumulatively reaching the printhead's nozzle plate. Hence, when using thick transparent substrates, there is a strong benefit for using a recording medium support for supporting a recording medium, the recording medium having an upper surface, the upper surface of the recording medium support comprising a black anodized metal.

[0031] Preferably, the thickness of the medium may be at least 10 mm, for example at least 15 mm, such as at least 20 mmBRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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 shows a schematic view of a first example of a printing system according to the present invention. Fig. 2 shows a graph representing the total energy measured as function of the print height for the comparison experiments.

[0033] In the drawing, same reference numerals refer to same elements.DETAILED DESCRIPTION OF THE DRAWINGS

[0034] Fig. 1 is a print system 5 comprising a number of workstations 8B, 8C, which may be personal computers or other devices for preparing image data for prints to be printed. These workstations have access to a network N for transferring print jobs comprising the image data to a print controller 8A that is configured to receive the print jobs. The print controller 8A may be part of the print system 5 connected to a control unit of the print system 5 via a connection 6. The print system 5 further comprises a print unit 2 attached to an armature 7 for applying colorants, for example cyan (C), magenta (M), yellow (Y), black (K) and white (W) colorant, or varnish to pieces 9, 9A of flat print media placed on a flatbed surface 1 in order to obtain a printed image. The print unit comprises one or more ink application units, such as ink jet print heads (not shown). The flatbed surface 1 forms the upper surface of the recording medium support. The flatbed surface 1 of the print system 5 comprises a black anodized metal. The armature 7 may be a gantry above the flat bed surface 1 as shown in Fig. 1 or a robot arm (not shown) moving in a plurality of directions over the flat bed surface 1. The flatbed surface 1 is the surface of the flatbed which is at least partially printable by the print unit 2. The pieces of media may be so small that they are completely placed on the flatbed surface 1, but a piece of media which is larger than the flatbed surface, in which case an image which is going to cover the whole piece of media must be printed into a plurality of parts of the image, is not excluded. A first piece 9A has already been printed upon, while the other pieces 91, 92 are not provided with any recording material yet. The print unit 2 reciprocally scans the flatbed surface 1 in the second direction X along a gantry 7 perpendicular to a first direction Y of the gantry 7 over the flatbed surface 1 along guiding parts 10. During printing of an image on the piece 9A of media the piece 91, 92, 9A of media is not moved on the flatbed surface 1. This way of working is advantageous for rigid print media. A print head which is as wide as the flatbed surface may also be envisaged within the scope of the invention. Such a print head may be moveable in at least one direction over the flatbed surface 1.Experiments and examples Methods Printing method

[0035] Prints were made on a Canon Arizona 2300 printer. Glass 0f 20 mm thickness was used as the recording medium. The printer was modified by replacing the print head for printing white ink by a Rhea light measuring unit, brand Admesy.Comparison experiments Experiment 1 (Ex 1)

[0036] A test-print was made. During printing, the radiation was measured by the light measurement unit. The radiation was expressed as energy [J m -2< ] per print. During the print experiment, a black anodized aluminum overlay of 2000 mm x 1000 mm x 2 mm (I x b x h) was placed on the table of the printer. The experiment was repeated for several print heights, i.e. distance between the print head and the recording medium support. The relation between the print height and the total energy measured by the light measuring unit is shown in Figure 2.Comparative experiment 1 (CE 1)

[0037] The experiment was performed in the same way as experiment 1, with the difference that a grey anodized aluminum overlay was used, instead of a black anodized aluminum overlay.

[0038] In Figure 2, the total energy measured as function of the print height is depicted for Experiments 1 as well as Comparative Experiment 1.

[0039] The higher the total energy, the more UV radiation has been reflected towards the print units. High total energies are hence disadvantageous, as UV radiation that reaches the print head may cause unwanted curing of the ink in or around the nozzles of the print head. For all experiments, it is observed that the total energy measured depends on the print height; the larger the print height, the more energy is reflected.

[0040] The total energy measured in Comparative Experiment 1 was higher than the total energy measured in Experiment 1. In Experiment 1, wherein the table of the printed was covered with black anodized aluminum, the total energy measured was lower than the total energy measured in the other experiment. Hence, by providing a black anodized aluminum surface, reflection of UV radiation was efficiently reduced.

[0041] 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. Printer comprising: • at least one print unit for ejecting a radiation-curable ink; • at least one curing unit; and • a recording medium support for supporting a recording medium, the recording medium support having an upper surface, the upper surface of the recording medium support comprising a black anodized metal.

2. Printer according to claim 1, wherein the printer further comprises a print carriage, the print carriage carrying the at least one print head.

3. Printer according to claim 2, wherein the print carriage further carries the at least one curing unit.

4. Printer according to any of the preceding claims, wherein the printer is selected from a flatbed printer or a hybrid printer.

5. Printer according to any of the preceding claims, wherein the recording medium support is provided with a plurality of suction holes.

6. Method for printing, the method comprising the steps of: • providing a recording medium; • applying an image onto the recording medium using a printer according to any of the claims 1-5.

7. Method according to claim 6, wherein the recording medium is a transparent recording medium having a thickness of at least 5 mm.

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