System and method for printing documents with textures

Abstract

SOLUTION: An aqueous inkjet printer also ejects drops of UV material onto an aqueous ink image and exposes the aqueous ink image and the UV material to UV radiation before passing the aqueous ink image and UV material through a thermal dryer. The exposure to the UV radiation pins the UV material to the aqueous ink image and an underlying substrate, and the thermal dryer fixes the aqueous ink image to the substrate while releasing free radicals from the UV material.EFFECT: The printer produces textured prints that do not have free radicals that can irritate skin or produce noxious odors.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] TECHNICAL FIELD This disclosure relates to inkjet printers, and more particularly to printing textures onto documents with such printers. [Background technology]

[0002] Inkjet imaging devices, such as inkjet printers, are well known. These printers eject liquid ink from a printhead to form an image on an image receiving surface. The printhead includes a plurality of inkjets arranged in some type of array. Each inkjet has a thermal or piezoelectric actuator coupled to a printhead controller. The printhead controller generates firing signals corresponding to digital data regarding the image. The actuators in the printhead respond to the firing signals by ejecting ink droplets onto an image receiving member to form an ink image that corresponds to the digital image used to generate the firing signals.

[0003] Textured printing is preferred for some forms of documents. For example, business cards, placards, and invitations are typically printed with raised or coated letters or graphics. The raised letters and graphics, as well as the gloss and variable reflectivity enabled by textured printing, are frequently perceived as more aesthetically pleasing than non-textured printing.

[0004] Aqueous inkjet printers use water-based or solvent-based inks in which pigments or other colorants are suspended or in solution. These inks have the advantage of being non-toxic and generally odorless. Furthermore, the vivid colors produced by water-based inks make them useful for fine art printing. When the water-based ink is ejected onto an image-receiving surface by a printhead, the water or solvent evaporates, stabilizing the ink image on the image-receiving surface. When water-based inks are ejected directly onto a medium, they tend to soak into the medium, and if the medium is porous, such as paper, the water in the ink changes the physical properties of the medium. Because the spread of ink droplets impacting the medium is a function of the properties and porosity of the medium surface, print quality can be inconsistent. Furthermore, because water-based inks tend to be absorbed by some media, they are not conducive to building layers useful for texture printing. It would be beneficial to be able to use water-based inks in texture printing. Summary of the Invention

[0005] A new inkjet printer combines water-based ink and UV-curable ink to produce textured prints. The printer includes a media transport configured to move a medium through the printer, at least one actuator operably connected to the media transport configured to operate the media transport to move the medium through the printer, at least two print heads, each print head having a plurality of ejectors and at least one print head configured to eject droplets of water-based ink toward the medium moving through the printer and at least one other print head configured to eject droplets of UV-curable material toward the medium after the droplets of water-based ink are deposited on the medium, a UV curing device configured to direct UV radiation toward the medium passing through the printer after the medium has passed the at least two print heads, and a thermal dryer configured to direct energy toward the medium passing through the printer after the medium has passed the UV curing device.

[0006] A method of operating a novel inkjet printer produces textured prints using aqueous ink. The method includes operating at least one actuator operably connected to a media transport device to move media through the printer, operating at least one print head having a plurality of ejectors to eject droplets of aqueous ink toward the media moving through the printer, operating at least one other print head having a plurality of ejectors to eject droplets of UV-curable material toward the media after the droplets of aqueous ink deposit on the media, operating a UV curing device to direct UV radiation toward the media passing through the printer after the media has passed the print head, and operating a thermal dryer to direct energy toward the media passing through the printer after the media has passed the UV curing device. [Brief explanation of the drawings]

[0007] The foregoing aspects and other features of an inkjet printer that produces textured prints using water-based and UV-curable inks, and its method of operation, are explained in the following description in connection with the accompanying drawings.

[0008] [Figure 1] 1 shows an inkjet printer configured to produce textured prints using water-based and UV-curable inks.

[0009] [Figure 2] FIG. 2 is a side view of a UV curing device or thermal dryer configuration used in the printer of FIG. 1.

[0010] [Figure 3] FIG. 2 is a flow diagram of a process for operating the system of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] For a general understanding of the inkjet printer and its uses disclosed herein, as well as details of the printer and its uses, reference is made to the drawings, in which like reference numerals represent like elements.

[0012] As used herein, the terms “printer,” “printing device,” or “imaging device” generally refer to a device that produces an image on a print medium with a marking material such as ink, and may encompass any such device, such as a digital copier, bookbinding machine, facsimile machine, multifunction machine, etc. Image data generally includes information in electronic form that is rendered and used to operate inkjet ejectors to form ink images on a print medium. Such data may include text, graphics, photographs, etc. The act of producing an image, e.g., a graphic, text, photograph, etc., on a print medium with colorants is generally referred to herein as printing or marking. The term “texture printing” refers to a printed image having raised features or a coating that enhances the underlying image. The term “water-based ink” refers to a marking material that has a high percentage of water or solvent relative to the amount of colorant dissolved or suspended in the liquid in the ink.

[0013] FIG. 1 shows a block diagram of an aqueous inkjet printer 100 configured to produce textured prints using aqueous and UV-curable inks. The printer 100 includes at least two arrays 104 of printheads, although the illustrated printer has four such arrays, a UV curing device 108, a thermal heater 110, a media transport 112, a pair of nip rollers 116 mounted around a member 120 extending in a cross-process direction across a media 124 carried by the media transport 112, one or more actuators for driving the media transport 112, and a controller 128 configured to operate the components of the printer 100. While the system 100 shown in FIG. 1 uses a single heat dryer, multiple heat dryers and transport belt extensions can be provided. As used herein, the term “heat dryer” refers to an arrangement of drying components operable to heat treat a printed substrate to evaporate water or other solvents from the printed image. As used herein, the terms "drying" and "drying" refer to the use of a form of energy to evaporate a liquid or solvent that can be directed along a predetermined path.

[0014] In FIG. 1 , the media transport 112 is implemented with an endless belt wrapped around two or more rollers, at least one of which is driven by one of the actuators 132 to rotate the belt around the roller. Other embodiments can use a media transport 112 such as a series of rotating nip rollers driven by one or more of the actuators 132. In some embodiments, the leading edge of a supply roll of media is fed through the printer to a take-up roll at the end of the printer. Support members on which the supply roll, take-up roll, or both are driven are driven to move the media from the supply roll to the take-up roll in a known manner. As used herein, the term “media” refers to individual substrates on an image receiving surface and continuous substrates on an image receiving surface. As used herein, the term “cross-process direction” refers to a direction perpendicular to the direction of substrate movement through print heads, curing devices, and thermal dryers that are also located in the plane of the substrate. As used herein, the term “process direction” refers to the direction of substrate movement through print heads, curing devices, and thermal dryers that are also located in the plane of the substrate.

[0015] The printhead array 104 is configured and operated in a known manner to eject droplets of water-based ink onto a substrate passing thereby to form an ink image on the substrate. The UV curing device 108 is configured to expose an image including UV-curable ink to electromagnetic radiation within a frequency range that at least partially cures the UV-curable ink. In some embodiments, the UV curing device is a single emitter that emits a radiation pattern with a width in the cross-process direction equal to the widest medium printed by the printer. In other embodiments, the UV curing device is comprised of multiple UV light emitters arranged in an array having a width in the cross-process direction equal to the widest medium printed by the printer. In these embodiments, the controller 128 can selectively activate the emitters in the array of the UV curing device 108 to expose the UV-ink-printed areas to radiation without using energy to illuminate non-UV-inked areas. The thermal dryer 110 uniformly heats the medium to a temperature sufficient to remove free radicals in the partially cured UV ink and remove enough water from the water-based ink in the printed image on the medium.

[0016] In previously known aqueous inkjet printers used for texture printing, the aqueous ink image is first thermally treated to adhere the image to the substrate. After thermal treatment, the aqueous ink image passes through a printhead, which ejects a UV-curable ink or coating material onto the fixed aqueous ink image. The UV-curable ink or coating material is then exposed to curing radiation. However, this process is subject to oxygen inhibition of the curing process. This oxygen inhibition can result in only partial curing of the UV material. Because the UV material contains free radicals, the partially cured image can irritate the skin of people who remove the printed media, and an unpleasant odor can permeate the environment surrounding the printer.

[0017] To address these issues, the printhead array 104 is configured with different material sources for ejection. For example, in one embodiment, four printhead arrays can be configured with different colored aqueous inks, such as cyan, yellow, magenta, and black, and a fifth printhead array is configured to eject a UV-curable material. The printhead array configured with aqueous inks is positioned to eject the aqueous ink onto the medium before the printhead array configured with UV-curable material ejects droplets of UV-curable material onto the aqueous image on the medium. The controller 128 uses image data for the print job to operate the printheads in the printhead array 104, such that droplets of aqueous ink are ejected onto the medium before droplets of UV-curable ink or coating material are ejected onto the aqueous image to provide texture to the printed image. The combined aqueous ink / UV-curable material image is then first exposed to UV-curing radiation to pin the UV-curable material to the aqueous-ink image and substrate. As used herein, the term "pinning" refers to exposing the UV-curable material to an amount of UV radiation sufficient to only partially cure the UV-curable material. The partially cured UV material remains in place to maintain the textured effect in the printed image. Subsequent thermal drying of the combined water-based ink / UV-curable material image both fixes the water-based ink to the substrate and removes free radicals from the UV-curable material. The result is a textured print that is safer and less offensive than previously known textured prints using UV-curable materials.

[0018] In one embodiment, the thermal dryer 110 is configured with infrared emitters that direct infrared radiation toward all areas of the media passing through. In another embodiment, microwave emitters are configured to direct microwave radiation toward the media. In these embodiments using infrared or microwave emitters, the emitters can be arranged in an array within the dryer 110, as described above with respect to UV curing devices, allowing the controller 128 to selectively activate the emitters to vary the amount of radiation illuminating different areas of the composite printed image. The intensity variation is achieved by the controller using coverage areas within the image derived from the image data used to operate the print head and the media type used in the print job. The type of media affects the ink absorption rate, so areas that receive less radiation can absorb more ink than areas that are more strongly irradiated. In other embodiments, one or more convection heaters or heat lamps can be used, with heated air generated by the heaters directed toward the passing media by a blower, fan, or other source of positive airflow. These embodiments are less amenable to varying the amount of heat applied to the composite image than embodiments with an array of selectively actuable emitters. In all printer embodiments, the controller 128 is configured with programmed instructions stored in a memory operatively connected to the controller that, when executed, cause the controller to operate the actuator 132 to vary the speed at which the media moves through the curing device 108 and the dryer 110. Slowing the media can delay exposure to UV radiation, thereby providing more time for absorption of the ink into the media. This absorption changes the ink height on the media and the corresponding texture created on the media. Furthermore, slowing the media speed through the UV curing device and dryer increases exposure to radiation and heat, respectively, to remove free radicals from the media.

[0019] FIG. 2 shows a side view of one embodiment of a thermal dryer 110 that can be used in the printer of FIG. 1. The thermal dryer 110 includes a housing 204, a plurality of members 208, and drying elements 212 attached to the members 208. The housing 204 encloses a volume of air and has openings that communicate with the space adjacent to the media as it passes through the housing 204. While the members 208 are shown extending across the housing 204 in the cross-process direction, the members can extend in the process direction if they are not separated from each other by a distance greater than the width of the area heated by each of the drying elements 212. This type of member / heating element configuration ensures that all or most of the entire surface area of ​​the passing media is heated. This same type of configuration can be used with UV emitters arranged in an array in a UV curing device, as described above. As noted above, the drying elements can be infrared emitters, microwave emitters, heat lamps, convection heaters, air blowers, etc. For embodiments of the drying element implemented with a heat lamp or convection heater, a source of pressurized air can be included to direct heat generated by the drying element to the media. The housing 204 can also include a vent opening 216, and a source of negative pressure 205 can be connected to the vent opening to draw evaporated water, solvent, and free radicals from the air within the volume of the housing 204. The housing 204 serves to retain the heated or dry air generated by the drying element to dry the ink image and release free radicals from the UV-curable ink.

[0020] Operation and control of the various subsystems, components, and functions of printer 100 is performed with the assistance of controller 128. Controller 128 is operatively connected to the components of printhead module 104 (and thus, printhead), UV curing device 108, thermal dryer 110, and actuator 132, which rotates media transport 112 and nip roller 116. Controller 128 may be, for example, a self-contained, dedicated minicomputer having a central processing unit (CPU) with electronic data storage and a display or user interface (UI) 50. Controller 128 may include, for example, sensor input and control circuits, as well as pixel placement and control circuits. In addition, the CPU reads, captures, prepares, and manages the flow of image data between an image input source, such as a scanning system or an online or workstation connection, and printhead modules 34A-34D. Thus, controller 128 is the main multitasking processor for operating and controlling all of the other machine subsystems and functions in printing system 100. To perform these operations, the controller 128 uses print job data such as media type, ink type, etc., along with image data that is used to drive the printing performed by the printheads.

[0021] The controller 128 can be implemented using a general-purpose or dedicated programmable processor that executes programmed instructions. Instructions and data needed to perform programmed functions are stored in memory operatively connected to the processor or controller. The processor, its memory, and interface circuits configure the controller to perform the operations described below. These components may be provided on a printed circuit card or as circuits within an application specific integrated circuit (ASIC). Each of the circuits may be implemented in a separate processor, or multiple circuits may be implemented on the same processor. Alternatively, the circuits may be implemented with individual components or circuits provided within a very large scale integrated (VLSI) circuit. The circuits described herein may also be implemented with a combination of processors, ASICs, individual components, or VLSI circuits.

[0022] A process for operating system 100 to print a textured image on media is shown in Figure 3. The process is performed by controller 128 executing program instructions stored in memory operatively connected to one or more controllers that, when executing the instructions, process data and operate components operatively connected to the controller to perform the tasks set forth in the process flow diagram.

[0023] Process 300 begins by receiving print job information, such as media type, ink type, and image data, used to operate a print head to eject droplets of water-based ink and UV-curable material in a pattern corresponding to the image data (block 304). The media transport begins passing media through the printer (block 308), and the print head forms an aqueous ink image on the media and is then operated to eject droplets of UV-curable material onto the aqueous image in a pattern corresponding to the image data for the texture pattern received in the print job data (block 312). The UV curing device is operated to pin the UV material pattern to the aqueous image and media (block 316). The thermal dryer and media transport actuators are operated to fix the aqueous image to the media and remove free radicals from the water-based ink image and UV material on the media (block 320). Operation of the thermal dryer includes operating a negative pressure source to draw evaporated water, solvent, and released free radicals from the thermal dryer, thereby allowing them to safely vent outside the printer environment. Additionally, operation of the thermal dryer includes selectively activating and deactivating radiators in the UV curing device and drying elements in the thermal dryer using image data of the water-based ink image and the UV curable material pattern. Once the print job is completed (block 324), the process stops.

[0024] It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems, applications, or methods. Various presently unforeseen or unanticipated substitutions, modifications, variations, or improvements may thereafter be made by those skilled in the art, which are also intended to be encompassed by the following claims.

Claims

1. 1. A printer comprising: a media transport configured to move media in a process direction through the printer; at least one actuator operably connected to the media transport device, the at least one actuator configured to operate the media transport device to move the media through the printer in the process direction; at least two printhead arrays arranged to follow each other in the process direction, each printhead in each of the at least two printhead arrays having a plurality of ejectors, at least one printhead array configured to eject droplets of an aqueous ink toward the medium moving through the printer, and at least one other printhead array configured to eject droplets of a UV-curable material toward the medium after droplets of the aqueous ink have been deposited on the medium; a UV curing device configured to direct UV radiation toward the media passing through the printer after the media has passed the at least two print head arrays, the UV curing device including a housing having a width in a cross-process direction spanning a distance corresponding to a widest media to be printed by the printer, a plurality of members extending across the housing, and a plurality of UV radiators attached to each member of the plurality of members extending across the housing, each UV radiator configured to direct UV radiation toward the media being moved by the media transport apparatus through the housing of the UV curing device in the process direction; a thermal dryer configured to direct energy toward the media passing in the process direction after the media has passed the UV curing device, the thermal dryer including: a plurality of members extending across a housing of the thermal dryer; an opening; a negative pressure source coupled to the opening in the housing that draws vaporized liquid and free radicals from the thermal dryer; and a plurality of drying elements attached to each member of the plurality of members extending across the housing of the thermal dryer, each drying element configured to direct energy toward the media passing through the housing of the thermal dryer; a controller operatively connected to the at least two print head arrays, the at least one actuator, the UV curing device, the negative pressure source, and the thermal dryer, the controller comprising: operating the at least one actuator to operate the media transport device to move media in the process direction through the printer; using image data to operate the ejectors in the at least two printhead arrays to eject droplets of water-based ink and droplets of UV material toward the media passing through the printer; operating the UV emitters in the UV curing device using image data to selectively fix the UV material to the water-based ink as the media passes through the housing of the UV curing device in the process direction; operating the heat dryer to evaporate liquid from the water-based ink on the media as the media passes through the heat dryer in the process direction, releasing free radicals from the UV material after the UV material is fixed to the water-based ink; and a controller configured to operate the negative pressure source to draw the evaporated liquid and the free radicals through the opening in the housing.

2. The printer of claim 1 , wherein the plurality of members extend in a process direction within the housing of the thermal dryer.

3. The printer of claim 1 , wherein the plurality of members extend in a cross-process direction within the housing of the thermal dryer.

4. The printer of claim 3 , wherein the drying element is a microwave emitter.

5. The printer of claim 3 , wherein the drying element is an infrared emitter.

6. The printer of claim 3 , wherein the drying element is a convection heater.

7. The printer of claim 1 , wherein the plurality of members extend in a process direction within the housing of the UV curing device.

8. The printer of claim 1 , wherein the plurality of members extend in a cross-process direction within the housing of the UV curing device.

9. The controller: The printer of claim 1 , further configured to operate the at least one actuator of the media transport apparatus to slow the entry of the media into the UV curing device.

10. The controller: The printer of claim 9 , further configured to operate the at least one actuator of the media transport apparatus to slow the passage of the media through the UV curing device.

11. The controller:

11. The printer of claim 10, further configured to operate the at least one actuator of the media transport device using the image data and data corresponding to the type of media being moved by the media transport device.

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