Image forming apparatus and method of manufacturing printed matter

Abstract

To provide an image forming apparatus and a method for manufacturing a printed matter capable of responding to user's demands for both high image quality printing and high productivity printing.SOLUTION: An image forming apparatus comprises a conveying mechanism for conveying a recording medium, an application device for applying a pretreatment liquid to the recording medium, an inkjet head, and a processor, and the processor performs control to perform application of the pretreatment liquid in a case where the recording medium is conveyed at a first conveying speed and an image is formed by the inkjet head, and not to perform application of the pretreatment liquid in a case where the recording medium is conveyed at a second conveying speed higher than the first conveying speed and an image is formed, the image forming apparatus comprising: The processor is configured to set the maximum dischargeable ink droplet amount in a case of forming an image at the first conveyance speed to a first droplet amount, set the maximum dischargeable ink droplet amount in a case of forming an image at the second conveyance speed to a second droplet amount smaller than the first droplet amount, and form, on the recording medium conveyed at the second conveyance speed, an image having a lower image quality than an image formed on the recording medium conveyed at the first conveyance speed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and a method for producing printed matter, and more particularly to an inkjet image forming technique. [Background technology]

[0002] Patent Document 1 describes an image forming apparatus that includes a pretreatment liquid applicator that applies a pretreatment liquid to a recording medium and a print head that ejects ink onto the recording medium that has been coated with the pretreatment liquid. This image forming apparatus is equipped with a means for controlling the amount of pretreatment liquid based on the conveyance speed of the recording medium, with the aim of forming an image that is uniform in image density and free of bleeding and overflow, even on recording media that do not have an ink-receiving layer, such as industrial printing paper. When the conveyance speed is fast, the amount of pretreatment liquid is reduced, and when the conveyance speed is slow, the amount of pretreatment liquid is increased to apply the pretreatment liquid to the recording medium.

[0003] Patent Document 2 focuses on the fact that some types of paper require the application of pretreatment liquid and others do not, and proposes a configuration in which an application process path is provided within an image forming device that applies pretreatment liquid to paper, and an application-free path that does not require the application of pretreatment liquid, and the paper transport path is switched based on the detection results of the paper type, and paper that does not require pretreatment application passes through the application-free path.

[0004] The image forming apparatus described in Patent Document 3 is equipped with a means for controlling the amount of pretreatment liquid applied to the surface of the recording medium based on the conveying speed, with the aim of improving the abrasion resistance of the recording medium on which an image is formed, and the amount of pretreatment liquid increases as the conveying speed increases. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-111941 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-137378 [Patent Document 3] Patent No. 6471791 Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Documents 1-3, in the field of inkjet printing, there is a known technology that applies a pretreatment liquid to the paper to be conveyed, then ejects ink to aggregate the coloring material, thereby achieving high-quality printing. This type of printing method that utilizes the aggregation reaction of two liquids is called a "two-liquid aggregation system." In contrast, a method that prints by ejecting ink without applying a pretreatment liquid is called a "one-liquid aggregation system."

[0007] Although two-liquid aggregation inkjet printing devices are capable of producing high-quality printed materials, they have not been able to fully meet user demands for even greater productivity in terms of printing speed. To improve productivity, it is necessary to increase the paper transport speed, which also necessitates high-speed application of the pretreatment liquid. When using a roller application method for the pretreatment liquid application process, there is a limit to the transport speed required for stable application, making it difficult to further increase the speed.

[0008] Furthermore, as the paper transport speed increases, the drying time after printing becomes shorter, which reduces the film strength of the printed surface and causes problems with film quality such as blocking, or causes problems such as curling and / or cockling due to insufficient drying.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide an image forming apparatus and a method for manufacturing printed matter that can solve at least one of the above-mentioned problems and meet user demands for both high-quality printing and high-productivity printing. [Means for solving the problem]

[0010] An image forming apparatus according to one aspect of the present disclosure includes a transport mechanism for transporting a recording medium, an application device for applying a pretreatment liquid to the recording medium, an inkjet head for ejecting ink, and a processor for controlling the transport speed of the recording medium and the application operation of the application device when forming an image on the recording medium by ejecting ink from the inkjet head, wherein the processor controls the application device to apply the pretreatment liquid when the recording medium is transported at a first transport speed to form an image on the recording medium, and controls the application device not to apply the pretreatment liquid when the recording medium is transported at a second transport speed that is faster than the first transport speed to form an image on the recording medium.

[0011] According to this aspect, the conveying speed of the recording medium can be changed, and whether or not to apply the pretreatment liquid (whether or not to apply the pretreatment liquid) is controlled in accordance with the change in the conveying speed. When an image is formed by conveying the recording medium at a first conveying speed, the device configuration is a two-liquid aggregation system in which the pretreatment liquid is applied. On the other hand, when an image is formed by conveying the recording medium at a second conveying speed that is faster than the first conveying speed, the device configuration can be a one-liquid aggregation system in which the pretreatment liquid is not applied.

[0012] This makes it possible to use a single image forming apparatus for both high-quality printing using a two-component aggregation system and high-productivity printing using a one-component aggregation system. The first and second conveying speeds may be predetermined speeds or may be speeds specified by the user. The "conveying speed" includes the concept of printing speed. The conveying speed may be expressed as the number of printed sheets per unit time or as the moving distance per unit time.

[0013] In an image forming apparatus according to another aspect of the present disclosure, the processor can be configured to accept input of an instruction to switch between a first mode in which the recording medium is transported at a first transport speed and a second mode in which the recording medium is transported at a second transport speed, and to perform control to apply pretreatment liquid when the first mode is specified, and not to apply pretreatment liquid when the second mode is specified.

[0014] In another aspect of the image forming apparatus of the present disclosure, the image forming apparatus may further include a drying device that dries ink adhered to the recording medium, and the processor may be configured to control the drying device to a first drying intensity when the recording medium is transported at a first transport speed, and to control the drying device to a second drying intensity that is higher than the first drying intensity when the recording medium is transported at a second transport speed.

[0015] According to this aspect, it is possible to suppress insufficient drying due to a shortened drying time caused by an increase in the conveying speed.

[0016] In an image forming apparatus according to another aspect of the present disclosure, the processor may be configured to set the drying strength of the drying device according to the thickness of the recording medium. According to this aspect, it is possible to perform an appropriate drying process according to the thickness of the recording medium used. The processor may be configured to set the drying temperature of the drying device to a higher value as the thickness of the recording medium increases.

[0017] In an image forming apparatus according to another aspect of the present disclosure, the processor may be configured to set the drying strength of the drying device depending on the type of recording medium. According to this aspect, it is possible to perform an appropriate drying process depending on the type of recording medium used. It is preferable that the processor be configured to set the drying strength of the drying device based on a combination of the type and thickness of the recording medium.

[0018] In an image forming apparatus according to another aspect of the present disclosure, the processor may be configured to set the drying strength of the drying device based on the content of an image to be formed on the recording medium. Because the amount of ink applied to the recording medium varies depending on the image content, it is preferable to adjust the drying conditions according to the image content.

[0019] In another aspect of the present disclosure, an image forming apparatus may further include an input device for specifying drying conditions for the drying device, and the processor may be configured to control the drying device in accordance with the drying conditions input via the input device. According to this aspect, a user can manually change the drying conditions via the input device.

[0020] In an image forming device according to another aspect of the present disclosure, the processor can be configured to cause the inkjet head to form an image on the recording medium at a first printing resolution when the recording medium is transported at a first transport speed, and to cause the inkjet head to form an image on the recording medium at a second printing resolution that is lower than the first printing resolution when the recording medium is transported at a second transport speed.

[0021] By lowering the print resolution, the amount of ink applied to the recording medium can be reduced, which makes it possible to suppress an increase in the drying strength required when transporting at the second transport speed.

[0022] In an image forming apparatus according to another aspect of the present disclosure, the processor can be configured to set the maximum amount of ink droplets ejected per dot from the nozzles of the inkjet head to a first droplet amount when an image is formed by transporting the recording medium at a first transport speed, and to set the maximum amount of ink droplets ejected to a second droplet amount that is smaller than the first droplet amount when an image is formed by transporting the recording medium at a second transport speed.

[0023] By reducing the maximum volume of ink droplets ejected, the amount of ink applied to the recording medium can be reduced, which makes it possible to suppress an increase in the drying strength required when transporting at the second transport speed.

[0024] In an image forming apparatus according to another aspect of the present disclosure, the application device includes an application roller that transfers the pretreatment liquid to the recording medium, and can be configured to prevent application of the pretreatment liquid by separating the application roller from the recording medium.

[0025] In the image forming apparatus according to another aspect of the present disclosure, the pretreatment liquid may contain an acid.

[0026] In the image forming apparatus according to another aspect of the present disclosure, the pretreatment liquid may contain at least one of a polyvalent metal salt and a cationic polymer.

[0027] In an image forming apparatus according to another aspect of the present disclosure, the inkjet head may be a line head.

[0028] In an image forming apparatus according to another aspect of the present disclosure, the same ink can be used when an image is formed on a recording medium by transporting the recording medium at a first transport speed and when an image is formed on the recording medium by transporting the recording medium at a second transport speed.

[0029] In the image forming apparatus according to another aspect of the present disclosure, the second conveying speed may be configured to be 1.2 times or more the first conveying speed.

[0030] A method for manufacturing a printed matter according to another aspect of the present disclosure is a method for manufacturing a printed matter using an image forming apparatus including: a conveying mechanism that conveys a recording medium; an application device that applies a pretreatment liquid to the recording medium; an inkjet head that ejects ink; and a processor that controls the conveying speed of the recording medium and the application operation of the application device when forming an image on the recording medium by ejecting ink from the inkjet head, wherein the processor receives input of an instruction to change the conveying speed, and, when a first conveying speed is specified as the conveying speed, causes the conveying mechanism to convey the recording medium at the first conveying speed, applies the pretreatment liquid to the recording medium by the application device, and forms an image on the recording medium by adhering ink ejected from the inkjet head to the recording medium to which the pretreatment liquid has been applied, and, when a second conveying speed faster than the first conveying speed is specified as the conveying speed, causes the conveying mechanism to convey the recording medium at the second conveying speed, does not apply the pretreatment liquid to the recording medium by the application device, and forms an image on the recording medium by adhering ink ejected from the inkjet head to the recording medium to which the pretreatment liquid has not been applied. [Effects of the Invention]

[0031] According to the present invention, it is possible to provide an image forming apparatus that can be used for both high-quality printing and high-productivity printing that emphasizes productivity. Furthermore, according to the present invention, it is possible to switch between high-quality printing and high-productivity printing depending on the application, and it is possible to handle not only the production of printed matter that emphasizes image quality but also the production of printed matter that emphasizes productivity. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a diagram showing the overall configuration of an inkjet printing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a side view showing an outline of the ink drying unit in the inkjet printing apparatus. [Figure 3] FIG. 3 is a functional block diagram showing a schematic configuration of a control system of the inkjet printing apparatus. [Figure 4] FIG. 4 is a chart showing examples of combinations of print resolution, maximum ejected ink droplet volume, and drying strength settings corresponding to the standard mode and high-speed mode. [Figure 5] FIG. 5 is a diagram showing an example of the settings of the drying condition table. [Figure 6] FIG. 6 is a flowchart showing an example of control when changing the conveying speed. [Figure 7] FIG. 7 is a table showing the evaluation results of the film strength of the printed surface when the combination of the conditions of the conveying speed and the drying strength is changed when the cardboard paper according to Example 1 is used. [Figure 8] FIG. 8 is a table showing the evaluation results of the film strength of the printed surface when the combination of the conditions of the conveying speed and the drying strength is changed in the case where thin paper according to Example 2 is used. [Figure 9] FIG. 9 is a perspective view of the inkjet head. [Figure 10] FIG. 10 is a partially enlarged view of the inkjet head as seen from the nozzle surface side. [Figure 11] FIG. 11 is a plan view of the nozzle surface of the head module as seen from the ejection side. [Figure 12] FIG. 12 is a vertical cross-sectional view showing the three-dimensional structure of one ejector in the head module. DETAILED DESCRIPTION OF THE INVENTION

[0033] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] <Configuration of Inkjet Printing Device> FIG. 1 is a diagram showing the overall configuration of an inkjet printing apparatus 1 according to an embodiment of the present invention. The inkjet printing apparatus 1 is an inkjet color digital printing apparatus that uses four colors of ink: cyan (C), magenta (M), yellow (Y), and black (K) to print a desired image on a sheet of paper P in a single pass. The inkjet printing apparatus 1 is an example of an "image forming apparatus" in this disclosure. In this embodiment, an example will be described in which aqueous ink is used as the ink for drawing. Aqueous ink refers to ink in which coloring materials such as pigments and dyes are dissolved or dispersed in water and / or a water-soluble solvent.

[0035] The inkjet printing apparatus 1 includes a paper feed unit 10, a treatment liquid deposition unit 20, a treatment liquid drying unit 30, a printing unit 40, an ink drying unit 50, and an accumulation unit 60.

[0036] The paper feed section 10 includes a paper feed device 12, a feeder board 14, and a paper feed drum 16. Paper P is placed on the paper feed tray 12A in a stack of many sheets. There are no particular restrictions on the type of paper P, but printing paper primarily made of cellulose, such as high-quality paper, coated paper, or art paper, can be used. The maximum paper size that can be used in the inkjet printing device 1 is, for example, 750 mm x 585 mm.

[0037] The paper feeder 12 takes out the sheets P from a stack set on the paper feed tray 12A one by one, starting from the top, and supplies them to the feeder board 14. The feeder board 14 transports the sheets P received from the paper feeder 12 to the paper feed drum 16.

[0038] The paper feed drum 16 receives the paper P fed from the feeder board 14 and transports the received paper P to the treatment liquid deposition unit 20.

[0039] The treatment liquid application unit 20 applies treatment liquid to the paper P. The term "treatment liquid" is synonymous with "pretreatment liquid." The treatment liquid may also be called a "precoat," "preconditioner," "undercoat liquid," or "treatment agent." The treatment liquid is a liquid that has the function of aggregating, insolubilizing, or thickening the colorant components in the ink. The treatment liquid application unit 20 includes a treatment liquid application drum 22 and a treatment liquid application device 24.

[0040] The treatment liquid application drum 22 receives the paper P from the paper feed drum 16 and transports the received paper P to the treatment liquid drying section 30. The treatment liquid application drum 22 is provided with a gripper 23 on the drum circumferential surface, and by rotating while gripping the leading edge of the paper P with the gripper 23, the paper P is wrapped around the drum circumferential surface and transported.

[0041] Treatment liquid application device 24 includes application roller 25, and applies treatment liquid to paper P transported by treatment liquid application drum 22. Application roller 25 is supported by a contact / separation mechanism (not shown) that is movable between an application position where it contacts paper P to apply treatment liquid to paper P, and a retracted position where it is separated from paper P and does not apply treatment liquid. The function of applying treatment liquid to paper P using treatment liquid application device 24 is called the "pre-coat function." Treatment liquid application device 24 is an example of an "application device" in this disclosure.

[0042] The pre-coating function can be selectively turned on / off in the inkjet printing device 1. When the pre-coating function is on, the application roller 25 is controlled to the application position, and when the pre-coating function is off, the application roller 25 is controlled to the retracted position.

[0043] The area to which the treatment liquid is applied to the paper P may be a full application, where the treatment liquid is applied to the entire paper P, or a partial application, where the treatment liquid is applied to a portion of the area to which ink is applied in the drawing unit 40. From the viewpoints of uniformly adjusting the amount of treatment liquid applied, uniformly recording thin lines and fine image portions, and suppressing density unevenness such as image irregularities, a full application, where the treatment liquid is applied to the entire image forming surface of the paper P by application using an application roller or the like, is preferred.

[0044] The method for applying the treatment liquid is not limited to the roller application method, and other methods may be applied to the treatment liquid application device 24. Examples of other methods for the treatment liquid application device 24 include application using a blade, ejection using an inkjet method, and atomization using a spray method.

[0045] The treatment liquid drying unit 30 dries the paper P on which the treatment liquid has been applied. The treatment liquid drying unit 30 includes a treatment liquid drying drum 32 and a warm air blower 34. The treatment liquid drying drum 32 receives the paper P from the treatment liquid application drum 22 and transports the received paper P to the imaging unit 40. The treatment liquid drying drum 32 includes a gripper 33 on the drum circumferential surface. The treatment liquid drying drum 32 transports the paper P by rotating while gripping the leading edge of the paper P with the gripper 33.

[0046] The warm air blower 34 is installed inside the treatment liquid drying drum 32. The warm air blower 34 blows warm air onto the paper P being transported by the treatment liquid drying drum 32, thereby drying the treatment liquid.

[0047] The imaging unit 40 includes an imaging drum 42, a head unit 44, and an image reading device 48. The imaging drum 42 receives the paper P from the treatment liquid drying drum 32 and transports the received paper P to the ink drying unit 50. The imaging drum 42 includes a gripper 43 on its circumferential surface, and by gripping the leading edge of the paper P with the gripper 43 and rotating, the paper P is wound around the drum circumferential surface and transported. The imaging drum 42 includes a suction mechanism (not shown), and the paper P wound around the drum circumferential surface is adsorbed to the drum circumferential surface and transported. Negative pressure is used for adsorption. The imaging drum 42 includes a number of suction holes on its circumferential surface, and the paper P is adsorbed to the circumferential surface of the imaging drum 42 by suction from inside the imaging drum 42 through these suction holes.

[0048] The head unit 44 is configured to include inkjet heads 46C, 46M, 46Y, and 46K. The inkjet head 46C is a recording head that ejects droplets of cyan ink. The inkjet head 46M is a recording head that ejects droplets of magenta ink. The inkjet head 46Y is a recording head that ejects droplets of yellow ink. The inkjet head 46K is a recording head that ejects droplets of black ink. Each of the inkjet heads 46C, 46M, 46Y, and 46K is supplied with ink from an ink tank (not shown), which is an ink supply source of the corresponding color, via a piping path (not shown).

[0049] Each of the inkjet heads 46C, 46M, 46Y, and 46K is configured as a line head that can print on the paper P transported by the imaging drum 42 in a single scan, i.e., by a single pass method. The inkjet heads 46C, 46M, 46Y, and 46K are arranged so that their nozzle surfaces face the circumferential surface of the imaging drum 42. The inkjet heads 46C, 46M, 46Y, and 46K are arranged at regular intervals along the transport path of the paper P by the imaging drum 42.

[0050] Although not shown in Figure 1, the nozzle surface of each of the inkjet heads 46C, 46M, 46Y, and 46K has a plurality of nozzles, which are ink ejection ports, arranged two-dimensionally. The term "nozzle surface" refers to the ejection surface on which the nozzles are formed, and is synonymous with terms such as "ink ejection surface" or "nozzle formation surface." A nozzle arrangement of a plurality of nozzles arranged two-dimensionally is called a "two-dimensional nozzle array."

[0051] Each of the inkjet heads 46C, 46M, 46Y, and 46K can be configured by connecting multiple head modules in the paper width direction. The paper width here refers to the paper width in the direction perpendicular to the transport direction of the paper P. The transport direction of the paper P is referred to as the Y direction. The paper width direction perpendicular to the Y direction is referred to as the X direction. Each of the inkjet heads 46C, 46M, 46Y, and 46K is a line-type recording head having a nozzle array that can record an image at a specified printing resolution over the entire recording area of ​​the paper P in the X direction with a single scan. This type of recording head is also called a "full-line type recording head" or "page-wide head."

[0052] The default print resolution may be a print resolution predetermined by the inkjet printing device 1, or may be a print resolution selected by the user or automatically selected by a program according to the print mode. For example, the print resolution may be 1200 dpi in the X direction and 1200 dpi in the Y direction. "dpi" stands for "dots per inch" and is a unit of measurement that indicates the number of dots (points) per inch. One inch is 25.4 millimeters (mm).

[0053] The paper width direction (X direction) perpendicular to the transport direction of the paper P is sometimes called the nozzle row direction of the line head, and the transport direction of the paper P (Y direction) is sometimes called the nozzle row perpendicular direction.

[0054] In the case of an inkjet head with a two-dimensional nozzle array, the projected nozzle array, in which each nozzle in the two-dimensional nozzle array is projected (orthogonally projected) along the nozzle array direction, can be considered equivalent to a single nozzle array in which the nozzles are arranged at approximately equal intervals in the nozzle array direction at a nozzle density that achieves maximum printing resolution. "Approximately equal intervals" means that the nozzles are substantially evenly spaced as droplet ejection points that can be recorded by an inkjet printing device. For example, the concept of "equally spaced" also includes cases in which the intervals are slightly different to account for droplet movement on the medium due to manufacturing errors and / or landing interference. The projected nozzle array corresponds to a virtual nozzle array. When considering the projected nozzle array, a nozzle number representing the nozzle position can be assigned to each nozzle in the order in which the projected nozzles are arranged along the nozzle array direction.

[0055] The nozzle arrangement in each of the inkjet heads 46C, 46M, 46Y, and 46K is not limited, and various nozzle arrangements can be adopted. For example, instead of a two-dimensional matrix arrangement, a linear nozzle arrangement, a V-shaped nozzle arrangement, or a polygonal nozzle arrangement such as a W-shape in which V-shaped arrangements are repeated, are also possible.

[0056] Ink droplets are ejected from at least one of the inkjet heads 46C, 46M, 46Y, and 46K toward the paper P being transported by the drawing drum 42, and an image is formed on the paper P by the ejected droplets adhering to the paper P.

[0057] The imaging drum 42 functions as a means for moving the inkjet heads 46C, 46M, 46Y, and 46K relative to the paper P. The imaging drum 42 is one form of relative movement means for moving the paper P relative to the inkjet heads 46C, 46M, 46Y, and 46K. The ejection timing of each of the inkjet heads 46C, 46M, 46Y, and 46K is synchronized with a rotary encoder signal obtained from a rotary encoder (not shown) that is installed on the imaging drum 42. The ejection timing is the timing at which ink droplets are ejected, and is synonymous with droplet ejection timing.

[0058] In this example, a configuration using four ink colors, CMYK, is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, special color ink, etc. may be added as needed. For example, a configuration is possible in which inkjet heads that eject light-colored inks such as light cyan and light magenta are added, and / or inkjet heads that eject special color inks such as green, orange, or white are added. Furthermore, the arrangement order of the inkjet heads of each color is not particularly limited.

[0059] The image reading device 48 is a device that optically reads an image recorded on paper P by inkjet heads 46C, 46M, 46Y, and 46K and generates electronic image data representing the read image. The image reading device 48 includes an imaging device that captures an image recorded on paper P and converts it into an electrical signal representing image information. In addition to the imaging device, the image reading device 48 may also include an illumination optical system that illuminates the object to be read and a signal processing circuit that processes a signal obtained from the imaging device to generate digital image data.

[0060] The image reading device 48 is preferably configured to be capable of reading color images. In this example, the image reading device 48 uses, for example, a color CCD (Charge-Coupled Device) linear image sensor as an imaging device. The color CCD linear image sensor is an image sensor in which light-receiving elements equipped with color filters of R (red), G (green), and B (blue) are linearly arranged. It should be noted that a color CMOS (Complementary Metal Oxide Semiconductor) linear image sensor may be used instead of the color CCD linear image sensor. The image reading device 48 reads the image on the paper P while the paper P is being transported by the imaging drum 42. An image reading device installed in this way on the paper transport path may be called an "inline scanner" or "inline sensor." The image reading device 48 may also be a camera.

[0061] When the paper P, on which an image has been recorded using at least one of the inkjet heads 46C, 46M, 46Y, and 46K, passes through the reading area of ​​the image reading device 48, the image on the paper P is read. The image recorded on the paper P may include a user image to be printed as specified in the print job, as well as a defective nozzle detection pattern for inspecting the ejection status of each nozzle, a test pattern for correcting print density, a test pattern for correcting uneven print density, and various other test patterns.

[0062] The printed image is inspected to determine whether there are any image quality abnormalities based on the data of the image read by the image reading device 48. Furthermore, based on the data of the image read by the image reading device 48, information such as the density of the image and the ejection status of each nozzle of the inkjet heads 46K, 46C, 46M, and 46Y can be obtained.

[0063] The ink drying unit 50 dries the paper P on which the image has been formed by the drawing unit 40. The ink drying unit 50 includes a chain gripper 70, a paper guide 80, and a heat drying processing unit 90.

[0064] The chain gripper 70 receives the paper sheet P from the imaging drum 42 and transports the received paper sheet P to the accumulation unit 60. The chain gripper 70 has a pair of endless chains 72 that travel along a specified travel path, and transports the paper sheet P along the specified transport path while gripping the leading edge of the paper sheet P with grippers 74 provided on the pair of chains 72. A plurality of grippers 74 are provided on the chains 72 at regular intervals.

[0065] The chain gripper 70 of this example is configured to include a first sprocket 71A, a second sprocket 71B, a chain 72, and a plurality of grippers 74, and has a structure in which a pair of endless chains 72 is wound around the pair of first sprockets 71A and second sprockets 71B. Only one of the pair of first sprockets 71A and second sprockets 71B and the pair of chains 72 is shown in Fig. 1.

[0066] The chain gripper 70 has a structure in which a plurality of grippers 74 are arranged at a plurality of positions in the feed direction (length direction) of the chain 72. The chain gripper 70 also has a structure in which a plurality of grippers 74 are arranged along the paper width direction between the pair of chains 72. Of the plurality of grippers 74 arranged between the pair of chains 72, only one gripper 74 is shown in Figure 1.

[0067] The transport path of the paper P by the chain gripper 70 includes a horizontal transport area where the paper P is transported horizontally, and an inclined transport area where the paper P is transported diagonally upward from the end of the horizontal transport area. The horizontal transport area is called the first transport section, and the inclined transport area is called the second transport section.

[0068] The paper guide 80 is a mechanism that guides the transport of paper P by the chain gripper 70. The paper guide 80 includes a first paper guide 82 and a second paper guide 84. The first paper guide 82 guides paper P transported through the first transport section of the chain gripper 70. The second paper guide 84 guides paper P transported through the second transport section subsequent to the first transport section.

[0069] 1, a detailed structure of the first paper guide 82 is not shown, but a suction conveying device 102 (see FIG. 2) is used as the first paper guide 82. The configuration of the suction conveying device 102 will be described in detail later.

[0070] The heating and drying processing unit 90 applies heat to the paper P on which an image has been formed by the drawing unit 40 to evaporate the ink solvent and dry the paper P. The heating and drying processing unit 90 is, for example, a hot air blowing unit, and is disposed opposite the first paper guide 82, and blows hot air onto the paper P being transported by the chain gripper 70.

[0071] The collecting section 60 includes a collecting device 62 that receives and collects the paper sheets P transported from the ink drying section 50 by a chain gripper 70. The chain gripper 70 releases the paper sheets P at a predetermined collecting position. The collecting device 62 includes a collecting tray 62A, receives the paper sheets P released from the chain gripper 70, and collects them in a bundle on the collecting tray 62A. The collecting section 60 corresponds to a paper discharge section.

[0072] <<Outline of the ink drying unit 50>> Figure 2 is a side view showing an overview of the ink drying unit 50 in the inkjet printing apparatus 1. In Figure 2, elements that are the same as those in the configuration shown in Figure 1 are given the same reference numerals, and their description will be omitted. To simplify the illustration in Figure 2, the image reading device 48, first sprocket 71A, and second sprocket 71B are not shown.

[0073] The ink drying unit 50 includes a heating and drying processing unit 90 and an adsorption and transport device 102. The heating and drying processing unit 90 includes, for example, an infrared lamp (not shown) as a heat source and an air blower (not shown). The adsorption and transport device 102 includes a belt 110, a drive roller 112, a driven roller 114, and a suction box 116.

[0074] The belt 110 is an endless belt and has a plurality of suction holes for attracting the paper P. The belt 110 is stretched over a drive roller 112 and a driven roller 114.

[0075] The drive roller 112 is driven to rotate in a counterclockwise direction in Fig. 2. As the drive roller 112 rotates, the belt 110 moves around in a counterclockwise direction in Fig. 2. The driven roller 114 rotates in a counterclockwise direction in Fig. 2, driven by the belt 110. In Fig. 2, the direction in which the belt 110 moves from the driven roller 114 toward the drive roller 112 corresponds to the transport direction of the paper P.

[0076] The belt 110 has a width in the X direction that is larger than the width in the X direction of the paper sheet P. The belt 110 supports the paper sheet P that is transported by the chain gripper 70, and transports the paper sheet P.

[0077] The outer peripheral surface of the belt 110 wound around the drive roller 112 and the driven roller 114 is referred to as the first surface of the belt 110. The surface of the belt 110 opposite to the first surface, i.e., the inner peripheral surface of the belt 110 wound around the drive roller 112 and the driven roller 114, is referred to as the second surface of the belt 110. The second surface may be referred to as the "back surface" of the belt 110.

[0078] The first surface of the belt 110 can be a conveying surface 110A that supports and conveys the paper P. The conveying surface 110A can also be called a "paper support surface." The paper P to be conveyed by the gripper 74 is placed on the conveying surface 110A of the belt 110. The suction conveying device 102 conveys the paper P along the conveying path in the Y direction by bringing the paper P, whose recording surface has been applied with ink, into contact with the conveying surface 110A of the belt 110. The conveying surface 110A forms a flat surface at least while it is in contact with the paper P.

[0079] In FIG. 2, the region of the belt circulation path of the belt 110 where the belt 110 moves from the driven roller 114 to the drive roller 112, i.e., the upper belt path in FIG. 2, is referred to as the first belt path. Also, the region of the belt circulation path where the belt 110 moves from the drive roller 112 to the driven roller 114, i.e., the lower belt path in FIG. 2, is referred to as the second belt path. The second belt path is the belt path on the return side. In this example, the conveying surface 110A is a plane parallel to the horizontal plane, but the conveying surface 110A may also be an inclined surface that intersects with the horizontal plane at an angle. For example, the second paper guide 84 may have a configuration similar to that of the suction conveying device 102.

[0080] The suction box 116 is disposed on the second surface side of the belt 110, i.e., the back surface side of the belt 110, in the space between the drive roller 112 and the driven roller 114. The suction box 116 is connected to an exhaust pump (not shown). A vacuum blower such as a ring blower can be used as the exhaust pump. The suction box 116 generates suction pressure in the suction holes of the belt 110. The region on the back surface side of the belt 110 in the first belt path where the suction box 116 is disposed becomes a suction area that suctions and adsorbs the paper P. The suction box 116 may be divided (separated) into multiple regions in the Y direction.

[0081] Furthermore, the suction conveying device 102 has infrared lamps 162, 164 disposed inside the drive roller 112 and the driven roller 114 along the rotation axis of each roller as means for heating the belt 110. The temperatures of the infrared lamps 162, 164 are set to a desired temperature, for example, in the range of 80°C to 150°C, and can be changed as needed.

[0082] The driving roller 112 and the driven roller 114 are heated by the infrared lamps 162, 164, and the heat is transferred to the belt 110, thereby indirectly heating the belt 110. By heating the belt 110, in combination with the heating and drying process by the heating and drying processing unit 90, the drying process can be carried out efficiently.

[0083] The paper P on which an image has been formed by the drawing unit 40 is transferred from the drawing drum 42 to the chain gripper 70, and with the leading edge of the paper P gripped by the gripper 74, it is placed on the belt 110 and adsorbed to the belt 110.

[0084] The chain gripper 70 transports the gripper 74 in synchronization with the rotation speed of the imaging drum 42. The drive roller 112 is rotationally driven to move the belt 110 in accordance with the feed speed of the gripper 74 by the chain gripper 70.

[0085] The belt 110 is fed at approximately the same speed as the gripper 74. The feed speed of the belt 110 and the feed speed of the gripper 74 do not necessarily have to be perfectly equal, and there may be a slight speed difference between them.

[0086] The speed difference between the belt 110 and the gripper 74 can vary depending on the size and / or stiffness of the paper sheet P. If the speed of the belt 110 is slightly slower than the speed of the gripper 74, the paper sheet P can be conveyed while applying a pulling force to the paper sheet P. Conversely, if the speed of the belt 110 is faster than the speed of the gripper 74, the belt 110 will push the paper sheet P in the conveyance direction as it moves forward.

[0087] Belt 110 has a belt length that allows it to simultaneously adsorb and convey multiple sheets of paper P. While belt 110 shown in Fig. 2 has a belt length that allows it to simultaneously adsorb and convey two sheets of paper P, the belt length of belt 110 can be designed appropriately, and it is also possible for it to be configured to simultaneously adsorb and convey three or more sheets of paper P. As an example of dimensions, the distance between drive roller 112 and driven roller 114 may be 1250 mm, and the adsorption distance of suction box 116 may be 1000 mm.

[0088] Overview of the control system of the inkjet printing device 1 3 is a functional block diagram showing a schematic configuration of a control system of the inkjet printing apparatus 1. The inkjet printing apparatus 1 includes a processor 300, a storage device 302, a communication unit 304, an input device 306, and a display device 308.

[0089] The processor 300 includes a CPU (Central Processing Unit). The processor 300 functions as a processing unit and / or a control unit that performs various processes by executing instructions from programs stored in the storage device 302. The processor 300 functions as a system control unit 310, an image processing unit 311, a conveyance control unit 312, a paper feed control unit 313, a treatment liquid application control unit 314, a treatment liquid drying control unit 316, a drawing control unit 318, an ink drying control unit 320, and a paper discharge control unit 324. The processing functions of each of these units may be realized using multiple processors. Furthermore, some of the processing functions required for processing and / or control may be realized using integrated circuits such as a DSP (Digital Signal Processor) or an FPGA (Field Programmable Gate Array).

[0090] The storage device 302 is a non-transitory, tangible computer-readable medium. The storage device 302 includes a memory serving as a main storage device and a storage serving as an auxiliary storage device. The storage device 302 may be, for example, a semiconductor memory, a hard disk drive (HDD), a solid state drive (SSD), or a combination of these. A part or all of the storage area of ​​the storage device 302 may be included in the processor 300.

[0091] The storage device 302 includes an image memory 332, a parameter storage unit 334, and a program storage unit 336. The image memory 332 functions as a temporary storage unit for various data including image data.

[0092] The parameter storage unit 334 stores various parameters used in the inkjet printing device 1. The various parameters stored in the parameter storage unit 334 are read out via the processor 300 and set in each unit of the device.

[0093] The program storage unit 336 stores programs used by each unit of the inkjet printing apparatus 1. The various programs stored in the program storage unit 336 are read out via the processor 300 and executed by each unit of the apparatus.

[0094] The system control unit 310 functions as an overall control unit that comprehensively controls each unit of the inkjet printing apparatus 1. The system control unit 310 also functions as a calculation unit that performs various calculation processes. Furthermore, the system control unit 310 controls the reading and writing of data in the storage device 302.

[0095] The communication unit 304 has a required communication interface. The inkjet printing apparatus 1 is connected to the host computer 400 via the communication unit 304, and can send and receive data to and from the host computer 400. Here, "connection" includes a wired connection, a wireless connection, or a combination of these. The communication unit 304 may be equipped with a buffer memory to speed up communication processing. The communication unit 304 serves as an image input interface unit for acquiring image data representing an image to be printed. The image data acquired from the host computer 400 via the communication unit 304 is stored in the image memory 332.

[0096] The image processing unit 311 performs various conversion processes, correction processes, and halftone processes on the image data to be printed. Conversion processes include pixel count conversion, gradation conversion, color conversion, etc. Correction processes include density correction and non-discharge correction to reduce the visibility of image defects caused by faulty nozzles. The image processing unit 311 performs correction processes based on the scanned image obtained from the image reading device 48. Halftone processing is generally a process of quantizing m-level (m is an integer equal to or greater than 3) multi-level image data and converting it into n-level (n is an integer equal to or greater than 2 and less than m) data. The image processing unit 311 converts, for example, an 8-bit (256 gradations) image signal for each color of CMYK into a signal (dot data) representing a multi-level dot arrangement of ternary or higher values, on a pixel-by-pixel basis.

[0097] Assuming that the inkjet heads 46C, 46M, 46Y, and 46K of the inkjet printing device 1 can eject three different droplet sizes (dot sizes): small, medium, and large. In this case, the image processing unit 311 converts the 8-bit color-separated image data for each color into four gradation (N=4) signals: "eject large ink droplets," "eject medium ink droplets," "eject small ink droplets," and "no ejection (no droplets)." This type of halftone processing can be performed using, for example, a dithering method or an error diffusion method.

[0098] The transport control unit 312 controls the operation of the transport mechanism 11. The transport mechanism 11 includes the mechanical elements related to the transport of the paper P from the paper feed unit 10 to the accumulation unit 60 described in FIG. 1. The transport mechanism 11 includes the paper feed drum 16, the treatment liquid application drum 22, the treatment liquid drying drum 32, the imaging drum 42, and the chain gripper 70 shown in FIG. 1. The transport mechanism 11 also includes a motor (not shown) as a power source and a drive unit such as a motor drive circuit (not shown). The transport control unit 312 controls the transport speed of the paper P by the transport mechanism 11 in response to commands from the system control unit 310, and also controls the transport of the paper P from the paper feed unit 10 to the accumulation unit 60.

[0099] The paper feed control unit 313 operates the paper feed unit 10 in response to a command from the system control unit 310. The paper feed control unit 313 controls the operation of starting and stopping the supply of paper P.

[0100] The treatment liquid application control unit 314 operates the treatment liquid application unit 20 in response to commands from the system control unit 310. The treatment liquid application control unit 314 controls the application operation of the treatment liquid application device 24, such as turning on / off the pre-coating function, the amount of treatment liquid to be applied, and the application timing.

[0101] The processing liquid drying control unit 316 operates the processing liquid drying unit 30 in response to commands from the system control unit 310. The processing liquid drying control unit 316 controls the drying temperature, the flow rate of the drying gas, and the timing of spraying the drying gas.

[0102] The drawing control unit 318 operates the drawing unit 40 in response to commands from the system control unit 310. The drawing control unit 318 includes a waveform storage unit, a waveform generation unit, and a drive circuit (not shown). The waveform storage unit stores the waveforms of the drive voltages to be applied to the ejection energy generating elements of the inkjet heads 46C, 46M, 46Y, and 46K. The waveform generation unit generates the waveforms of the drive voltages. The drive circuit generates drive voltages having drive waveforms corresponding to the dot data.

[0103] Based on the dot data for each ink color generated through halftone processing by the image processing unit 311, the drawing control unit 318 controls the ejection operation of each of the inkjet heads 46C, 46M, 46Y, and 46K so as to record an image on the paper P transported by the drawing drum 42. That is, based on the dot data generated through processing by the image processing unit 311, the ejection timing and ink ejection amount for each pixel position are determined, a drive voltage corresponding to the ejection timing and ink ejection amount for each pixel position, and a control signal for determining the ejection timing for each pixel are generated, and this drive voltage is supplied to the inkjet heads 46C, 46M, 46Y, and 46K, and dots are recorded on the paper P using the ink ejected from the inkjet heads 46C, 46M, 46Y, and 46K.

[0104] The drawing control unit 318 can output a predetermined command signal to each of the inkjet heads 46C, 46M, 46Y, and 46K to check the state of the nozzles, and control the printing of the nozzle state evaluation pattern.

[0105] The ink drying control unit 320 operates the ink drying unit 50 in response to a command from the system control unit 310. The ink drying control unit 320 controls the temperature of the drying gas, the flow rate of the drying gas, the ejection timing of the drying gas, and the like.

[0106] The paper discharge control unit 324 operates the stacking unit 60 in response to a command from the system control unit 310. When the stacking device 62 shown in Fig. 1 includes a lifting mechanism, the paper discharge control unit 324 controls the operation of the lifting mechanism in response to an increase or decrease in the number of sheets P.

[0107] The input device 306 is configured, for example, by operation buttons, a keyboard, a mouse, a touch panel, a multi-touch screen, other pointing devices, a voice input device, or an appropriate combination of these. The input device 306 accepts various inputs from an operator. The display device 308 is configured, for example, by a liquid crystal display, an organic electro-luminescence (OEL) display, a projector, or an appropriate combination of these.

[0108] Information input via the input device 306 is sent to the system control unit 310. The system control unit 310 executes various processes in accordance with the information input from the input device 306.

[0109] The display device 308 can display various information such as various setting information of the device or abnormality information in response to commands from the system control unit 310. A user (operator) can use the input device 306 to set various parameters and input and edit various information while viewing the content displayed on the display device 308.

[0110] Overview of Operation of Inkjet Printing Device 1 In order to enable both high-quality printing and high-productivity printing with a single device, the inkjet printing device 1 has a standard mode in which paper is transported at a standard transport speed that prioritizes high image quality, and a high-speed mode for improving productivity, and is configured to be able to selectively switch between these modes. The high-speed mode is a mode in which paper is transported at a speed faster than the standard transport speed that prioritizes productivity, and multiple modes with different transport speeds may be prepared.

[0111] As a specific example, we will show a configuration in which the standard conveying speed in standard mode is 3600 sph, and two conveying speeds are available in high-speed mode: 5400 sph and 7200 sph, and either conveying speed can be selected. Note that "sph" is a unit that represents the number of printed sheets per hour (sheets / hour). The standard mode and at least one high-speed mode may be selectable for each print job.

[0112] The standard mode may be referred to as a "high-image-quality mode," and the high-speed mode as a "high-productivity mode." These modes with different conveying speeds may be understood as types of conveying modes or types of printing modes. The standard mode is an example of a "first mode" in the present disclosure. The high-speed mode is an example of a "second mode" in the present disclosure. 3600 sph is an example of a "first conveying speed" in the present disclosure. 5400 sph and 7200 sph are each an example of a "second conveying speed" in the present disclosure. In this embodiment, an example is shown in which the conveying speed in the high-speed mode is set to 1.5 to 2 times the standard conveying speed, but the conveying speed in each of the standard mode and the high-speed mode can be set appropriately. Preferably, the conveying speed in the high-speed mode is 1.2 times or more the standard conveying speed.

[0113] The motor used as the power source of the transport mechanism 11 (hereinafter referred to as the transport drive motor) is driven by inverter control. When switching the transport speed in accordance with a change in transport mode, the processor 300 changes the frequency of the inverter control, thereby changing the rotation speed of the transport drive motor.

[0114] Furthermore, when the inkjet printing device 1 switches to high-speed mode, the function for applying treatment liquid (pre-coating function) is turned off, and printing is performed using a one-liquid aggregation system. When standard mode is selected, the pre-coating function is turned on, and the inkjet printing device 1 performs printing using a two-liquid aggregation system. That is, when the pre-coating function is on (standard mode), the application roller 25 repeatedly contacts and separates with each sheet of paper P, transferring treatment liquid to the paper P. On the other hand, when the pre-coating function is off (high-speed mode), the application roller 25 is always kept separated, and no application is performed. This configuration makes it possible to switch between a one-liquid aggregation system configuration and a two-liquid aggregation system configuration without changing the transport path of the paper P.

[0115] Furthermore, the inkjet printing apparatus 1 changes the drying intensity of the ink drying unit 50 in accordance with the change in conveyance speed. The drying function of the drying unit, which includes the heating and drying processing unit 90 and infrared lamps 162 and 164 located downstream of the image forming unit 40, is concerned that the increased speed of paper conveyance may result in insufficient drying if the drying process is equivalent to that in standard mode. Insufficient drying can cause, for example, curling, worsening cockling, worsening blocking, and reduced film resistance. For this reason, when switching to high-speed mode, the inkjet printing apparatus 1 also changes the drying intensity of the drying unit to a table of drying conditions consistent with high-speed mode, thereby increasing the drying intensity compared to standard mode.

[0116] While it is preferable to increase the drying intensity of the ink drying unit 50 when printing in high-speed mode, it is possible to reduce the increase in drying intensity by combining a reduction in the maximum ink droplet volume and a reduction in print resolution. Specifically, while the maximum ink droplet volume in standard mode is 4.5 pl to 5.5 pl, in high-speed mode, this can be reduced to 2.5 pl to 3.5 pl, thereby reducing the total amount of ink applied to the paper P and the required drying capacity. The maximum ink droplet volume refers to the maximum volume of ink droplets ejected to form one dot by each of the inkjet heads 46C, 46M, 46Y, and 46K, and refers to the maximum volume of ink droplets ejected per dot from each head. To change the maximum ink droplet volume, for example, the volume of large droplets may be changed, or the volume of medium droplets may be set as the "maximum ink droplet volume" by disabling the use of large droplets.

[0117] Furthermore, in standard mode, the print resolution is, for example, 1200 dpi x 1200 dpi, whereas in high-speed mode, the Y-axis resolution is reduced to, for example, 1200 dpi x 600 dpi. This reduces the total amount of ink used, thereby enabling the required drying capacity to be reduced. 1200 dpi x 1200 dpi is an example of a "first print resolution" in this disclosure. 1200 dpi x 600 dpi is an example of a "second print resolution" in this disclosure.

[0118] Figure 4 is a chart showing example combinations of print resolution, maximum ink droplet volume, and drying strength settings for standard mode and high-speed mode. In high-speed mode, by increasing the drying strength compared to standard mode in conjunction with at least one of reducing the maximum ink droplet volume and reducing the print resolution, it is possible to suppress insufficient drying and maintain print performance, such as curl, cockle, and film quality, equivalent to that of standard mode.

[0119] Furthermore, since the drying strength required to maintain printing performance differs depending on the type and thickness of the paper P used for printing, it is desirable to change the drying strength within each paper thickness range. In the inkjet printing device 1 according to this embodiment, there are drying condition tables for each paper thickness range for each paper type in both standard mode and high-speed mode.

[0120] FIG. 5 is a chart showing an example of a setting for the drying condition table. FIG. 5 shows an example of setting the drying temperature for each paper thickness range for gloss-coated paper. The "hot air temperature" in FIG. 5 is the temperature of the hot air blown out from the heating and drying processing unit 90. The "belt temperature" is the temperature of the belt 110 of the suction and conveying device 102. The drying process is performed by hot air blown from above onto the printed surface of the paper P and by heat transfer from the belt 110 that suctions and holds the paper P, so it is necessary to set the temperature for both of these. Although not shown in FIG. 5, appropriate drying temperatures are also determined for each paper thickness range for paper types other than gloss-coated paper, such as matte paper. The processor 300 reads the corresponding drying condition table and sets the temperature according to the paper type and thickness of the paper P being used.

[0121] Furthermore, the drying conditions are not limited to being automatically set according to a table, but may be manually set by the user via the input device 306. The processor 300 can control the drying device in accordance with the drying conditions input via the input device 306.

[0122] <Relationship between print quality and transport speed> In high-speed mode, print quality is thought to be lower than in standard mode because no treatment liquid is applied and the print resolution is lower. In high-speed mode, the ink dot diameter is larger than in standard mode due to the lack of pre-coating (single-liquid aggregation system), so granularity and / or boundary reproducibility (inter-color bleeding) are thought to be worse than in standard mode.

[0123] Additionally, high-speed mode reduces print resolution compared to standard mode, which is thought to result in worse character and line reproducibility. Depending on the printing application, users will use high-speed mode for print jobs that require high productivity even if it means lower image quality, and standard mode for print jobs where image quality is important. High-speed mode improves productivity, with 5400sph being 1.5 times faster than standard mode (3600sph), and 7200sph being twice as fast.

[0124] <<Example of printing operation in inkjet printing device 1>> 6 is a flowchart showing an example of a printing operation in the inkjet printing apparatus 1. FIG. 6 shows an example of control when changing the conveying speed. In step S11, the processor 300 accepts input specifying a conveying mode. For example, the processor 300 accepts input of information specifying the standard mode or high-speed mode from the input device 306. Alternatively, the processor 300 may set the standard mode as the default setting in accordance with a program command, and accept an instruction to change to the high-speed mode via the input device 306.

[0125] In step S12, the processor 300 determines whether the specified mode is the standard mode or the high-speed mode. If the result of the determination in step S12 is the "standard mode," the processor 300 proceeds to step S13.

[0126] In step S13, the processor 300 sets the transport speed to the standard transport speed, which may be, for example, 3600 sph.

[0127] Next, in step S14, the processor 300 turns on the pre-coat function, causing the inkjet printing apparatus 1 to function as a two-liquid aggregation system apparatus.

[0128] Then, in step S15, the processor 300 sets the print resolution to the standard print resolution, which may be, for example, 1200 dpi x 1200 dpi.

[0129] Next, in step S16, processor 300 sets the maximum ejected ink droplet volume to a standard value. The standard value of the maximum ejected ink droplet volume may be, for example, a value in the range of 4.5 pL to 5.5 pL. This standard value is an example of the "first droplet volume" in this disclosure.

[0130] Next, in step S17, the processor 300 sets the drying strength of the ink drying unit 50 to standard drying strength. The drying conditions for standard drying strength and the drying conditions for high drying strength, which will be described later, are stored in advance in the storage device 302 as table data according to the type and thickness of the paper P used for printing. The processor 300 can read out the drying conditions that match the type and thickness of the paper P used from the table data. Information on the type and thickness of the paper P may be input from the input device 306, or may be input using a barcode reader (not shown). After step S17, the processor 300 proceeds to step S30. The order of the processes in steps S13 to S17 can be changed as appropriate.

[0131] On the other hand, if the determination result in step S12 is the "high-speed mode", the processor 300 proceeds to step S23.

[0132] In step S23, the processor 300 sets the conveying speed to a high conveying speed, which may be, for example, 5400 sph or 7200 sph depending on the type of high-speed mode specified.

[0133] Next, in step S24, the processor 300 turns off the pre-coating function. This causes the inkjet printing apparatus 1 to function as a single-liquid aggregation system apparatus. When the pre-coating function is turned off, the drying process in the treatment liquid drying unit 30 is also turned off.

[0134] Next, in step S25, the processor 300 sets the print resolution to a low print resolution that is lower than the standard print resolution. The low print resolution may be, for example, 1200 dpi x 600 dpi.

[0135] Next, in step S26, processor 300 sets the maximum ink droplet volume to a reduced value that is less than the standard value. The reduced value of the maximum ink droplet volume may be any value less than the standard value, and may be, for example, a value within the range of 2.5 pL to 3.5 pL. This reduced value is an example of the "second droplet volume" in this disclosure.

[0136] Next, in step S27, the processor 300 sets the drying strength of the ink drying unit 50 to a high drying strength that is higher than the standard drying strength. After step S27, the processor 300 proceeds to step S30. Note that the order of the processes in steps S23 to S27 can be changed as appropriate.

[0137] In step S30, processor 300 accepts the selection of a print job. When a print job to be processed is designated by input from the user, etc., processor 300 determines in step S32 whether or not to change the drying strength.

[0138] If the determination result in step S32 is YES, the processor 300 proceeds to step S33. In step S33, the processor 300 sets the drying intensity according to the print image. That is, the processor 300 corrects (changes) the setting of the drying intensity according to the image content to be printed specified in the print job. This is a process of evaluating the total amount of ink from the image to be printed and changing the drying conditions to more appropriate conditions according to the total amount of ink.

[0139] After step S32, the processor 300 proceeds to step S34. If the determination result of step S32 is a NO determination, the processor 300 proceeds to step S34.

[0140] In step S34, the processor 300 executes printing in accordance with the specifications of the print job. When the standard mode is set, the transport mechanism 11 transports the paper P at a standard transport speed (3600 sph), the treatment liquid application device 24 applies treatment liquid to the paper P, and droplets are ejected from the inkjet heads 46C, 46M, 46Y, and 46K onto the paper P that has been coated with the treatment liquid. On the other hand, when the high-speed mode is set, the transport mechanism 11 transports the paper P at a high transport speed (5400 sph or 7200 sph), the treatment liquid application device 24 does not apply treatment liquid, and droplets are ejected from the inkjet heads 46C, 46M, 46Y, and 46K onto the paper P that has not been coated with treatment liquid. In this way, an image is formed on the paper P, and after a drying process in the ink drying unit 50, a printed product is obtained. After step S34, the processor 300 ends the flowchart of FIG. 6. The printing method according to the flowchart of FIG. 6 is an example of a "method for manufacturing a printed product" in this disclosure.

[0141] Example 1 Below, we will explain the evaluation results of the film quality performance (film quality strength) of the printed surface when the combination of conditions of conveyance speed and dry strength is changed using a specific brand of paper P. In Example 1, "Ibest" (registered trademark: Nippon Paper Industries Co., Ltd.) with a basis weight of 310 gsm (paper thickness 0.34 mm) was used as paper P, and the film quality strength was evaluated when the combination of conditions of conveyance speed and dry strength was changed. Example 1 corresponds to the performance evaluation of so-called "thick paper." The evaluation results are shown in Figure 7. Note that the basis weight is the manufacturer's nominal value, and the unit gsm is "g / m 2 "

[0142] Film strength is an index that shows the hardness of the coating on the printed surface. The film strength was measured using a pendulum hardness tester on paper P immediately after printing, drying, and ejection.

[0143] Film strength is a property that substitutes for blocking performance and / or film quality. Blocking refers to the peeling of printed surfaces due to overlapping of printed materials. Film quality refers to abrasion resistance and scratch resistance.

[0144] The symbol A shown in FIG. 7 and FIG. 8 described later indicates the performance (film quality strength) that meets the product specifications. Regarding the other symbols "A+", "B", "C", "D", etc., based on the symbol A, they indicate the performance in the permutation of D < C < B < A < A+. The evaluation of "A+" indicates particularly excellent performance, and the evaluations of "B" to "D" are at levels that do not meet the product specifications.

[0145] Regarding the maximum ejected ink droplet volume and the printing resolution, at a conveyance speed of 3600 sph, printing is performed with a setting of a maximum ejected ink droplet volume of 5 pl and a printing resolution of 1200 dpi × 1200 dpi. At conveyance speeds of 5400 sph and 7200 sph, printing is performed with a setting of a maximum ejected ink droplet volume of 3.5 pl and a printing resolution of 1200 dpi × 600 dpi.

[0146] The notation "Standard (150°C / 120°C)" indicates that the setting of the drying strength is the standard drying strength, and shows that the hot air temperature as the drying condition of the ink drying unit 50 is 150°C and the belt temperature is 120°C. The standard drying strength is an example of the "first drying strength" in the present disclosure.

[0147] The notation "UP (170°C / 140°C)" indicates that the drying strength is a high drying strength that is enhanced (up) compared to the standard drying strength, and shows that the hot air temperature is 170°C and the belt temperature is 140°C. The high drying strength is an example of the "second drying strength" in the present disclosure.

[0148] It has been confirmed that the film quality strength deteriorates by increasing the conveyance speed while maintaining the standard drying strength, and it deteriorates further at 7200 sph. In contrast, by increasing the drying strength, it becomes possible to maintain the film quality strength at the product specification level even when the conveyance speed is increased.

[0149] Note that these results were obtained when the maximum amount of ink droplets ejected was the same, and it was confirmed that film quality improved by reducing the maximum amount of ink droplets ejected. Furthermore, the results showed that curl and cockle, which are other print quality characteristics, were hardly affected by increasing the conveying speed or increasing the dry strength when using IBEST (registered trademark: Nippon Paper Industries Co., Ltd.) with a basis weight of 310 gsm.

[0150] Example 2 In Example 2, "OK Topcoat+" (Oji Paper Co., Ltd.) with a basis weight of 104 gsm (paper thickness of 0.09 mm) was used as paper P, and the film strength was evaluated when the combination of conveying speed and dry strength conditions was changed. Example 2 corresponds to a performance evaluation of so-called "thin paper." The evaluation results are shown in Figure 8. The evaluation method, as well as the settings of the maximum ink droplet volume and print resolution, were the same as in Example 1.

[0151] In Example 2, the drying conditions for standard dry strength were a hot air temperature of 100°C and a belt temperature of 90°C. Furthermore, the drying conditions for high dry strength were a hot air temperature of 110°C and a belt temperature of 100°C. In the case of "OK Topcoat+" with a basis weight of 104 gsm, increasing the conveying speed while maintaining the standard dry strength resulted in a deterioration in film strength, but not as drastically as with IBEST (registered trademark) with a basis weight of 310 gsm. At 5400 sph, the film strength remained almost unchanged, and at 7200 sph, it only slightly deteriorated. Therefore, by slightly increasing the dry strength above the standard dry strength, it became possible to maintain film strength at or above the product specification level.

[0152] On the other hand, for thin paper, if the drying strength is too high, the paper deformation will increase, and there is a concern that curl and / or cockle will worsen. Also, if the drying strength is too low, curl and / or cockle will worsen, so there is an optimum drying strength for thin paper. The UP (110 / 100°C) condition shown in Figure 8 is considered to be the maximum drying strength that allows paper deformation such as curl and / or cockle.

[0153] <<About the ink used for printing>> In the inkjet printing apparatus 1 according to this embodiment, the same ink is used in both high-speed mode (one-component aggregation system) and standard mode (two-component aggregation system). By using the same ink when printing in standard mode and high-speed mode, ink is not replaced for each conveyance speed, eliminating waste when the conveyance speed is switched. This improves overall productivity when printing for multiple purposes while switching between conveyance modes.

[0154] <Examples of processing liquid> The treatment liquid used in this embodiment contains a component (aggregation-inducing component) that, upon contact with the ink compositions of each color (CMYK), causes the components in the ink compositions to aggregate and form aggregates containing the pigment. Examples of this aggregation-inducing component include a component selected from acidic compounds, polyvalent metal salts, and cationic polymers. In addition to the aggregation-inducing component, the treatment liquid may contain other components as needed. The treatment liquid is typically in the form of an aqueous solution. Using the treatment liquid together with the ink composition enables inkjet printing to be performed at a higher speed, and even at high speeds, images with high density and high resolution can be obtained, with excellent printability, for example, excellent reproducibility of fine lines and fine details.

[0155] <Acidic compounds> The acidic compound functions as a fixative by coming into contact with the ink composition on a recording medium to aggregate (fix) the components in the ink composition. Examples of the acidic compound include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid, metaphosphoric acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, nicotinic acid, oxalic acid, and benzoic acid. From the viewpoint of both suppressing volatilization and solubility in a solvent, the acidic compound is preferably an acid having a molecular weight of 35 to 1,000, more preferably an acid having a molecular weight of 50 to 500, and particularly preferably an acid having a molecular weight of 50 to 200. Furthermore, from the viewpoint of achieving both prevention of ink bleeding and photocurability, the acid dissociation constant pKa (in H2O, 25°C) of the acid is preferably from -10 to 7, more preferably from 1 to 7, and particularly preferably from 1 to 5.

[0156] Among these, acidic compounds with high water solubility are preferred. Furthermore, from the viewpoint of reacting with the ink composition to fix the entire ink, trivalent or lower acidic compounds are preferred, and divalent or trivalent acidic compounds are particularly preferred. The treatment liquid may contain one acidic compound alone or two or more acidic compounds in combination.

[0157] When the treatment liquid is an aqueous solution containing an acidic compound, the pH of the treatment liquid (at 25° C.) is preferably 0.1 to 6.8, more preferably 0.1 to 6.0, and even more preferably 0.1 to 5.0.

[0158] When the treatment liquid contains an acidic compound as an aggregating component, the content of the acidic compound in the treatment agent is preferably 40% by mass or less, more preferably 15 to 40% by mass, even more preferably 15 to 35% by mass, and particularly preferably 20 to 30% by mass. By adjusting the content of the acidic compound in the treatment agent to 15 to 40% by mass, the components in the aqueous ink composition can be fixed more efficiently.

[0159] When the treatment liquid contains an acidic compound as an aggregation-inducing component, the amount of the treatment liquid to be applied to the recording medium is not particularly limited as long as it is an amount sufficient to aggregate the ink composition. However, from the viewpoint of facilitating fixation of the ink composition, the amount of the acidic compound to be applied is preferably 0.5 g / m 2 ~4.0g / m 2 It is preferable to apply the treatment agent so that the amount is 0.9 g / m 2 ~3.75g / m 2 It is preferable to apply the treatment agent so that

[0160] <Polyvalent metal salts> The treatment solution preferably contains one or more polyvalent metal salts as an aggregation-inducing component. The inclusion of a polyvalent metal salt as an aggregation-inducing component can improve high-speed aggregation. Examples of polyvalent metal salts include salts of alkaline earth metals (e.g., magnesium, calcium) from Group 2 of the periodic table, salts of transition metals (e.g., lanthanum) from Group 3 of the periodic table, salts of cations (e.g., aluminum) from Group 13 of the periodic table, and salts of lanthanides (e.g., neodymium). Suitable metal salts include carboxylates (e.g., formate, acetate, benzoate), nitrate, chloride, and thiocyanate. Among these, calcium or magnesium salts of carboxylic acids (e.g., formate, acetate, benzoate), calcium or magnesium salts of nitrate, calcium chloride, magnesium chloride, and calcium or magnesium salts of thiocyanate are preferred.

[0161] When the treatment liquid contains a polyvalent metal salt as an aggregation-inducing component, the content of the polyvalent metal salt in the treatment liquid is preferably 1 to 10 mass %, more preferably 1.5 to 7 mass %, and even more preferably 2 to 6 mass %, from the viewpoint of the aggregation-inducing effect.

[0162] <Cationic Polymer> The treatment liquid also preferably contains one or more cationic polymers as an aggregation-inducing component. The cationic polymer is preferably a homopolymer of a cationic monomer having a primary, secondary, or tertiary amino group or a quaternary ammonium salt group as the cationic group, or a copolymer or condensation polymer of this cationic monomer with a non-cationic monomer. The cationic polymer may be used in the form of either a water-soluble polymer or water-dispersible latex particles.

[0163] Specific preferred examples of cationic polymers include poly(vinylpyridine) salts, polyalkylaminoethyl acrylates, polyalkylaminoethyl methacrylates, poly(vinylimidazole), polyethyleneimines, polybiguanides, polyguanides, and polyallylamine and its derivatives. From the viewpoint of the viscosity of the treatment liquid, the smaller the weight-average molecular weight of the cationic polymer, the better. From the viewpoint of the aggregation-inducing effect, the content of the cationic polymer in the treatment liquid is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and even more preferably 2 to 20% by mass.

[0164] <Other additives> The treatment liquid may further contain other additives as other components within a range that does not impair the intended flocculation effect. Examples of other additives include known additives such as drying inhibitors (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, antifoaming agents, viscosity adjusters, dispersants, dispersion stabilizers, rust inhibitors, and chelating agents.

[0165] <<Inkjet head configuration example>> Inkjet heads 46K, 46C, 46M, and 46Y have a common structure, and therefore will be described here as inkjet head 46.

[0166] Figure 9 is a perspective view of the inkjet head 46. Figure 9 shows the nozzle surface of the inkjet head 46 viewed from diagonally below. The inkjet head 46 is a full-line type line head in which multiple head modules 212 are arranged in the paper width direction to form an elongated line head.

[0167] 9 shows an example in which 17 head modules 212 are connected together, but the structure of the head modules 212 and the number and arrangement of the head modules 212 are not limited to the example shown in the figure. Reference numeral 214 in the figure denotes a base frame that serves as a framework for connecting and fixing multiple head modules 212 in a bar shape. Reference numeral 216 denotes a flexible substrate connected to each head module 212. Multiple head modules 212 are attached to the base frame 214 and integrated to form a single bar-shaped inkjet head 46.

[0168] Figure 10 is a partially enlarged view of the inkjet head 46 as viewed from the nozzle surface side. The head module 212 is supported by module support members 218B from both sides in the vertical direction in Figure 10, which is the short direction of the inkjet head 46, and is attached to the base frame 214 via the module support members 218B. In addition, both ends of the inkjet head 46 in the longitudinal direction are supported by head protection members 218D.

[0169] Although individual nozzles are not shown in FIG. 10, the diagonal solid line shown and labeled with reference numeral 224A represents a nozzle row in which a plurality of nozzles are aligned in a row.

[0170] Figure 11 is a plan view of the nozzle surface 212A of the head module 212, viewed from the ejection side. For convenience of illustration, the number of nozzles is reduced in Figure 11, but for example, 32 x 64 nozzles 220 are arranged two-dimensionally on the nozzle surface 212A of one head module 212. In addition, a liquid-repellent film is formed on the nozzle surface 212A.

[0171] 11 is the paper transport direction, and the X direction perpendicular to the Y direction is the paper width direction. The head module 212 has a long side end face along the V direction inclined at an angle γ with respect to the X direction, and a short side end face along the W direction inclined at an angle α with respect to the Y direction, and has a parallelogram shape in a plan view.

[0172] By connecting a plurality of such head modules 212 in the X direction, a nozzle row that covers the entire drawing range of the paper P in the X direction is formed, and a line head that can record an image at a specified recording resolution in a single drawing scan is configured. Note that the full-line type line head applied to the single-pass method is not limited to cases where the entire surface of the paper P as the recording medium is the printing range, and in cases where only a part of the recording medium is the printing area (for example, when a margin is provided around the recording medium), it is sufficient that the nozzle row required for printing is formed.

[0173] 12 is a vertical cross-sectional view showing the three-dimensional structure of one ejector 222 in the head module 212. The ejector 222 includes a nozzle 220, a pressure chamber 250 communicating with the nozzle 220, and a piezoelectric element 252. The nozzle 220 communicates with the pressure chamber 250 via a nozzle flow path 254. The pressure chamber 250 communicates with a supply-side common flow path 226 via an individual supply path 224.

[0174] The diaphragm 256 that forms the top surface of the pressure chamber 250 has a conductive layer (not shown) that functions as a common electrode corresponding to the lower electrode of the piezoelectric element 252. The walls of the pressure chamber 250 and other flow path portions, the diaphragm 256, etc. can be made of silicon. The material of the diaphragm 256 is not limited to silicon, and it can also be made of a non-conductive material such as resin. A conductive layer made of a conductive material is formed on the surface of the diaphragm member. Note that the diaphragm 256 itself may be made of a metal material such as stainless steel, and may also serve as a diaphragm that also serves as a common electrode.

[0175] A piezoelectric unimorph actuator is formed by a structure in which piezoelectric elements 252 are stacked on a vibration plate 256. Applying a drive voltage to individual electrodes 258, which are the upper electrodes of the piezoelectric elements 252, deforms the piezoelectric body 260, causing the vibration plate 256 to bend, thereby changing the volume of the pressure chamber 250. The pressure change that accompanies this volume change causes ink to be ejected from the nozzle 220. When the piezoelectric element 252 returns to its original state after ejecting ink, new ink is filled into the pressure chamber 250 from the supply-side common flow path 226 through the individual supply path 224. The action of filling the pressure chamber 250 with ink is called "refill." This example illustrates a configuration in which the vibration plate 256 is bent using the distortion deformation of the piezoelectric body 260 in the d31 mode, but ejection using the d33 mode or shear mode (shear deformation) is also possible.

[0176] The shape of the pressure chamber 250 in plan view is not particularly limited, and may be any of a variety of shapes, such as a rectangle or other polygon, a circle, or an ellipse.

[0177] Furthermore, the head module 212 of this example includes a recovery-side common flow path 280, and individual recovery paths 282 are connected to the nozzle flow paths 254 of each ejector 222. The individual recovery paths 282 are connected to the recovery-side common flow path 280.

[0178] Reference numeral 266 in FIG. 12 denotes a cover plate. The cover plate 266 is a member that maintains a movable space 268 for the piezoelectric element 252 and seals the periphery of the piezoelectric element 252. A supply-side ink chamber and a recovery-side ink chamber (not shown) are formed above the cover plate 266. The supply-side ink chamber is connected to the supply-side common flow path 226 via a communication path (not shown). The recovery-side ink chamber is connected to the recovery-side common flow path 280 via a communication path (not shown). Ink supplied to the pressure chamber 250 from the supply-side common flow path 226 via the individual supply path 224 passes through the nozzle flow path 254 and is ejected from the nozzle 220. Ink not used for ejection is recovered from the nozzle flow path 254 via the individual recovery path 282 to the recovery-side common flow path 280.

[0179] When there is a pressure difference between the pressure in the supply side common flow path 226 and the pressure in the recovery side common flow path 280 and ink is not being ejected from the ejector 222, ink flows from the individual supply path 224 through the pressure chamber 250 and the individual recovery path 282 to the recovery side common flow path 280.

[0180] By employing such an ink circulation structure, it is possible to prevent the ink in the pressure chamber 250 from thickening, thereby improving ejection stability. During refilling when ink is ejected from the ejector 222, ink is supplied from the supply-side common flow path 226 to the pressure chamber 250 via the individual supply path 224, and ink is supplied from the recovery-side common flow path 280 to the pressure chamber 250 via the individual recovery path 282. In other words, the recovery-side common flow path 280 not only serves to recover ink from the ejector 222, but also to supply ink to the ejector 222 during refilling.

[0181] <<Hardware configuration of various processing units and control units>> The hardware structure of the processing units that perform various processes, such as the system control unit 310, image processing unit 311, transport control unit 312, paper feed control unit 313, treatment liquid application control unit 314, treatment liquid drying control unit 316, drawing control unit 318, ink drying control unit 320, paper discharge control unit 324, and communication unit 304 described in FIG. 3, is made up of various processors as shown below.

[0182] Various types of processors include a CPU (Central Processing Unit), which is a general-purpose processor that executes programs and functions as various processing units, a programmable logic device (PLD), such as an FPGA (Field Programmable Gate Array), which is a processor whose circuit configuration can be changed after manufacture, and a dedicated electrical circuit, such as an ASIC (Application Specific Integrated Circuit), which is a processor with a circuit configuration designed specifically to execute specific processing.

[0183] A single processing unit may be configured with one of these various processors, or may be configured with two or more processors of the same or different types. For example, a single processing unit may be configured with multiple FPGAs, or a combination of a CPU and an FPGA. Alternatively, multiple processing units may be configured with a single processor. A first example of multiple processing units configured with a single processor is a configuration in which one or more CPUs and software are combined to form a single processor, as typified by client or server computers, and this processor functions as multiple processing units. A second example is a configuration in which a processor is used to realize the functions of an entire system including multiple processing units on a single IC (Integrated Circuit) chip, as typified by a system-on-chip (SoC). In this way, the various processing units are configured with one or more of the above-mentioned various processors as a hardware structure.

[0184] Furthermore, the hardware structure of these various processors is, more specifically, an electric circuit made up of a combination of circuit elements such as semiconductor elements.

[0185] <<About the program that makes a computer function as a control device>> A program that causes a computer to realize the control functions of the inkjet printing device 1 described in the above embodiment can be recorded on a computer-readable medium, such as an optical disk, a magnetic disk, or other tangible, non-transitory information storage medium, and the program can be provided through this information storage medium.Instead of providing the program by storing it on such a tangible, non-transitory information storage medium, it is also possible to provide a program signal as a download service using a communication network such as the Internet.

[0186] Advantages of the embodiment [1] According to the inkjet printing apparatus 1 of the embodiment, the two-component aggregation system and the one-component aggregation system are automatically switched in accordance with the switching between the standard mode and the high-speed mode, so that one apparatus can be used for two purposes: high-quality printing and high-productivity printing. In other words, the inkjet printing apparatus 1 is capable of high-quality printing in the standard mode (two-component aggregation system), while switching to the one-component aggregation system enables high-speed conveyance in the high-speed mode, enabling high-productivity printing.

[0187] [2] In high-speed mode, the drying intensity is automatically changed to a table corresponding to the high-speed mode, and the drying intensity is made higher than in standard mode, eliminating insufficient drying due to high-speed transport.

[0188] Variation 1 In the above embodiment, an inkjet printing device 1 using a page-wide full-line head is described, but the scope of application of the present invention is not limited to this, and the present invention can also be applied to inkjet printing devices that form images by moving a short recording head, such as a serial head, and scanning the head multiple times.

[0189] Variation 2 In the above embodiment, an example in which aqueous ink is used has been described, but ultraviolet-curable ink may be used instead of aqueous ink. When ultraviolet-curable ink is used, the inkjet printing apparatus 1 includes an ultraviolet irradiation device instead of or in addition to the heating and drying treatment unit 90.

[0190] <Inkjet head ejection method> An ejector of an inkjet head includes a nozzle that ejects ink, a pressure chamber connected to the nozzle, and an ejection energy generating element that applies ejection energy to the liquid in the pressure chamber. Regarding the ejection method for ejecting droplets from the nozzle of the ejector, the means for generating the ejection energy is not limited to a piezoelectric element, and various ejection energy generating elements such as a heating element or an electrostatic actuator can be used. For example, a method can be adopted in which droplets are ejected by utilizing the pressure of film boiling caused by heating the liquid with a heating element. Depending on the ejection method of the inkjet head, a corresponding ejection energy generating element is provided in the flow path structure.

[0191] <<About recording media>> In the above embodiment, an example has been described in which sheet paper P is used as the recording medium, but the medium used for recording images is not limited to sheet paper, and may be a continuous medium such as continuous paper. Furthermore, the sheet paper is not limited to cut paper that has been cut to a predetermined size in advance, but may be obtained by cutting a continuous medium to a predetermined size as needed.

[0192] The term "recording medium" is a general term for various terms such as paper, recording paper, printing paper, printing medium, print medium, print-receiving medium, image-forming medium, image-receiving medium, image-receiving medium, and ejection-receiving medium. The material and shape of the medium are not particularly limited, and various sheet bodies can be used, regardless of material or shape, such as sticker paper, resin sheet, film, cloth, nonwoven fabric, and others.

[0193] <<Regarding the recording medium transport mechanism>> The conveying mechanism for conveying the recording medium is not limited to the drum conveying system illustrated in FIG. 1, but various other systems such as a belt conveying system, a nip conveying system, a chain conveying system, and a pallet conveying system can be adopted, and these systems can be combined as appropriate.

[0194] <<Terminology>> The term "printing device" is synonymous with terms such as printing press, printer, printing device, image recording device, image forming device, image output device, or drawing device.

[0195] "Image" is to be interpreted broadly and includes color images, black and white images, single color images, gradation images, uniform density (solid) images, etc. "Image" is not limited to photographic images, but is used as a comprehensive term that includes designs, characters, symbols, line drawings, mosaic patterns, color-coded patterns, other various patterns, or appropriate combinations of these.

[0196] The term "printing" includes concepts of terms such as image recording, image formation, printing, drawing, and printing. The term "drawing" includes concepts of terms such as image recording, image formation, and digital printing based on digital data.

[0197] <Combinations of embodiments and modifications> The configurations described in the above embodiments and the features described in the modified examples can be used in appropriate combinations, and some features can also be replaced.

[0198] The above-described embodiments of the present invention may be modified, added, or deleted as appropriate within the scope of the spirit of the present invention. The present invention is not limited to the above-described embodiments, and many modifications are possible within the technical concept of the present invention by those having ordinary skill in the relevant field. [Explanation of symbols]

[0199] 1. Inkjet printing device 10 Paper feed section 11. Transport mechanism 12 Paper feeder 12A paper feed tray 14 Feeder Board 16 Paper feed drum 20 Processing liquid application section 22 Processing liquid application drum 23 Gripper 24 Processing liquid application device 25 Application roller 30 Processing liquid drying section 32 Processing liquid drying drum 33 Gripper 34 Warm air blower 40 Drawing section 42 Drawing Drum 43 Gripper 44 Head Unit 46 Inkjet head 46C inkjet head 46M inkjet head 46Y inkjet head 46K inkjet head 48 Image reader 50 Ink drying unit 60 Accumulation section 62 Accumulation Device 62A Accumulation Tray 70 Chain Gripper 71A 1st sprocket 71B 2nd sprocket 72 Chain 74 Gripper 80 Paper guide 82 First Paper Guide 84 Second Paper Guide 90 Heating and drying processing section 102 Adsorption transport device 110 Belt 110A conveying surface 112 drive roller 114 driven roller 116 Suction Box 162 Infrared lamp 164 Infrared Lamp 212 Head Module 212A Nozzle surface 214 base frame 218B Module support member 218D Head protection material 220 nozzle 222 Ejector 224 Individual supply route 224A nozzle row 226 Supply side common flow path 250 Pressure Chamber 252 Piezoelectric element 254 Nozzle flow path 256 Diaphragm 258 individual electrodes 260 Piezoelectric 266 Cover Plate 268 Movable space 280 Recovery side common flow path 282 Individual Collection Route 300 processors 302 Storage device 304 Communications Department 306 Input Device 308 Display device 310 System Control Unit 311 Image Processing Unit 312 Transport control unit 313 Paper feed control unit 314 Processing liquid application control unit 316 Processing liquid drying control unit 318 Drawing control unit 320 Ink drying control unit 324 Paper ejection control unit 332 Image Memory 334 Parameter storage unit 336 Program Memory Unit 400 host computer P paper S11 to S34: Processing steps in the inkjet printing device

Claims

1. a conveying mechanism for conveying a recording medium; an application device that applies a pretreatment liquid to the recording medium; an inkjet head that ejects ink; a processor that controls a conveyance speed of the recording medium and a coating operation by the coating device when an image is formed on the recording medium by ejecting the ink from the inkjet head, the processor causes the application device to apply the pretreatment liquid when the recording medium is transported at a first transport speed and the image is formed on the recording medium; an image forming apparatus, wherein when the recording medium is conveyed at a second conveying speed that is faster than the first conveying speed and an image is formed on the recording medium, control is performed so that the application device does not apply the pretreatment liquid, The processor: when the recording medium is transported at the first transport speed to form the image, a maximum ejection ink droplet volume per dot of the ink ejected from the nozzles of the inkjet head is set to a first droplet volume; when the image is formed by conveying the recording medium at the second conveying speed, the maximum amount of ink droplets to be ejected is set to a second droplet amount that is smaller than the first droplet amount; forming an image on the recording medium transported at the second transport speed that has a lower image quality than the image formed on the recording medium transported at the first transport speed; Image forming device.

2. the processor accepts an input of an instruction to switch between a first mode in which the recording medium is transported at the first transport speed and a second mode in which the recording medium is transported at the second transport speed; When the first mode is specified, the application of the pretreatment liquid is performed, and when the second mode is specified, the application of the pretreatment liquid is not performed. The image forming apparatus according to claim 1 .

3. a drying device that dries the ink that has been applied to the recording medium, the processor controls the drying device to a first drying intensity when the recording medium is transported at the first transport speed, and controls the drying device to a second drying intensity higher than the first drying intensity when the recording medium is transported at the second transport speed; 3. The image forming apparatus according to claim 1.

4. a conveying mechanism for conveying a recording medium; an application device that applies a pretreatment liquid to the recording medium; an inkjet head that ejects ink; a processor that controls a conveyance speed of the recording medium and a coating operation by the coating device when an image is formed on the recording medium by ejecting the ink from the inkjet head, the processor accepts an input of an instruction to change the conveying speed; when a first conveying speed is designated as the conveying speed, conveying the recording medium at the first conveying speed by the conveying mechanism, applying the pretreatment liquid to the recording medium by the application device, and forming an image on the recording medium by causing the ink ejected from the inkjet head to adhere to the recording medium on which the pretreatment liquid has been applied; when a second conveying speed higher than the first conveying speed is designated as the conveying speed, conveying the recording medium by the conveying mechanism at the second conveying speed, not applying the pretreatment liquid to the recording medium by the application device, and forming an image on the recording medium by depositing the ink ejected from the inkjet head onto the recording medium to which the pretreatment liquid has not been applied, The processor: when the recording medium is transported at the first transport speed to form the image, a maximum ejection ink droplet volume per dot of the ink ejected from the nozzles of the inkjet head is set to a first droplet volume; when the image is formed by conveying the recording medium at the second conveying speed, the maximum amount of ink droplets to be ejected is set to a second droplet amount that is smaller than the first droplet amount; A method for manufacturing a printed matter, comprising forming an image on the recording medium transported at the second transport speed, the image having a lower image quality than the image formed on the recording medium transported at the first transport speed.

Images