Image forming apparatus and method for manufacturing printed materials

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 manufacturing a printed matter, and particularly relates to an inkjet image forming technology.

Background Art

[0002] Patent Document 1 describes an image forming apparatus including a pretreatment liquid applicator that applies a pretreatment liquid to a recording medium, and a printing head that discharges ink onto the recording medium to which the pretreatment liquid has been applied. This image forming apparatus is intended to form an image with high image density and no bleeding, without unevenness in image density even on a recording medium such as industrial printing paper that has no ink receiving layer. It is provided with means for controlling the amount of the pretreatment liquid based on the conveyance speed of the recording medium. When the conveyance speed is high, the amount of the pretreatment liquid is reduced, and when it is low, the amount of the pretreatment liquid is increased to apply the pretreatment liquid to the recording medium.

[0003] Patent Document 2 focuses on the fact that there are papers that require application of a pretreatment liquid and papers that do not depending on the type of paper, and provides a coating process path for applying the pretreatment liquid to the paper and a non - coating path for papers that do not require pretreatment liquid application within the image forming apparatus. A configuration is proposed in which the conveyance path of the paper is switched based on the detection result of the paper type, and papers that do not require pretreatment coating are passed through the non - coating path.

[0004] The image forming apparatus described in Patent Document 3 is provided with means for controlling the amount of the pretreatment liquid applied to the surface of the recording medium based on the conveyance speed for the purpose of improving the abrasion resistance of the recording medium on which an image is formed. The higher the conveyance speed, the greater the amount of the pretreatment liquid is increased.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] As described in Patent Documents 1-3, in the field of inkjet printing, a technique is known in which a pretreatment solution is applied to the transported paper before ejecting ink, thereby agglomerating the colorants to achieve high-quality printing. This type of printing method that utilizes a two-liquid agglomeration reaction is called a "two-liquid agglomeration system." In contrast, a method that prints by ejecting ink without applying a pretreatment solution is called a "one-liquid agglomeration system."

[0007] While two-component condensation inkjet printing systems are capable of producing high-quality prints, they have not adequately met user demands for even higher productivity in terms of printing speed. Improving productivity requires increasing the paper transport speed, which in turn necessitates high-speed application of the pre-treatment solution. However, when using a roller application method for the pre-treatment solution, there is a limit to the transport speed at which stable application can be achieved, making further speed increases difficult.

[0008] Furthermore, the increased paper transport speed shortens the drying time after printing, which can lead to a decrease in the film strength of the printed surface, causing problems with film quality such as blocking, or problems such as curling and / or cuckling due to insufficient drying.

[0009] This invention has been made in view of these circumstances, and aims to provide an image forming apparatus and a method for manufacturing printed materials 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, a coating device for coating a pretreatment solution onto the recording medium, an inkjet head for ejecting ink, and a processor for controlling the transport speed of the recording medium and the coating operation by the coating device when forming an image on the recording medium by ejecting ink from the inkjet head. The processor controls the application of the pretreatment solution by the coating device when the recording medium is transported at a first transport speed to form an image on the recording medium, and refrains from applying the pretreatment solution by the coating device when the recording medium is transported at a second transport speed faster than the first transport speed to form an image on the recording medium.

[0011] According to this embodiment, the transport speed of the recording medium can be changed, and the application or non-application of the pretreatment solution (application or non-application) is controlled in accordance with the change in transport speed. When the recording medium is transported at a first transport speed to form an image, the apparatus configuration is a two-liquid condensation system in which the pretreatment solution is applied. On the other hand, when the recording medium is transported at a second transport speed, which is faster than the first transport speed, to form an image, the apparatus configuration may be a one-liquid condensation system in which the pretreatment solution is not applied.

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

[0013] In an image forming apparatus according to another aspect of the present disclosure, the processor can be configured to receive an input 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 perform the application of a pretreatment solution when the first mode is specified, and to refrain from applying the pretreatment solution when the second mode is specified.

[0014] In an image forming apparatus according to another aspect of the present disclosure, a drying device for drying ink attached to a recording medium may be further provided, 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 embodiment, it is possible to suppress insufficient drying caused by a reduction in drying time due to an increase in the conveying speed.

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

[0017] In an image forming apparatus according to another aspect of this disclosure, the processor may be configured to set the drying intensity of the drying apparatus according to the type of recording medium. According to this aspect, it is possible to perform appropriate drying processing according to the type of recording medium used. Preferably, the processor is configured to set the drying intensity of the drying apparatus based on a combination of the type and thickness of the recording medium.

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

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

[0020] In an image forming apparatus according to another aspect of the present disclosure, when the processor conveys a recording medium at a first conveyance speed, the processor causes an inkjet head to form an image on the recording medium at a first print resolution, and when the processor conveys the recording medium at a second conveyance speed, the processor causes the inkjet head to form an image on the recording medium at a second print resolution lower than the first print resolution.

[0021] By reducing the print resolution, the amount of ink applied to the recording medium can be decreased. Thereby, it is possible to suppress an increase in the required drying strength during conveyance at the second conveyance speed.

[0022] In an image forming apparatus according to another aspect of the present disclosure, when the processor conveys a recording medium at a first conveyance speed to form an image, the processor sets the maximum discharge ink droplet amount per dot of ink discharged from the nozzles of the inkjet head to a first droplet amount, and when the processor conveys the recording medium at a second conveyance speed to form an image, the processor sets the maximum discharge ink droplet amount to a second droplet amount smaller than the first droplet amount.

[0023] By reducing the maximum discharge ink droplet amount, the amount of ink applied to the recording medium can be decreased. Thereby, it is possible to suppress an increase in the required drying strength during conveyance at the second conveyance speed.

[0024] In an image forming apparatus according to another aspect of the present disclosure, the coating device includes a coating roller that transfers a pretreatment liquid to the recording medium, and the coating of the pretreatment liquid can be made not to be performed by separating the coating roller from the recording medium.

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

[0026] In image forming apparatus according to other embodiments of this disclosure, the pretreatment solution may be configured to include at least one of a polyvalent metal salt and a cationic polymer.

[0027] In image forming apparatuses according to other embodiments of this disclosure, the inkjet head may be configured as a line head.

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

[0029] In image forming apparatus according to other embodiments of this disclosure, the second transport speed may be configured to be 1.2 times or more the first transport speed.

[0030] A method for manufacturing a printed material according to another aspect of the present disclosure is a method for manufacturing a printed material using an image forming apparatus comprising: a transport mechanism for transporting a recording medium; a coating device for applying a pretreatment solution to the recording medium; an inkjet head for ejecting ink; and a processor for controlling the transport speed of the recording medium and the coating operation by the coating device when forming an image on the recording medium by ejecting ink from the inkjet head, wherein the processor receives an input instruction to change the transport speed, and when a first transport speed is specified as the transport speed, the transport mechanism transports the recording medium at the first transport speed, the coating device applies a pretreatment solution to the recording medium, and forms an image on the recording medium by adhering ink ejected from the inkjet head to the recording medium to which the pretreatment solution has been applied, and when a second transport speed faster than the first transport speed is specified as the transport speed, the transport mechanism transports the recording medium at the second transport speed, the coating device does not apply the pretreatment solution to the recording medium, and forms an image on the recording medium by adhering ink ejected from the inkjet head to the recording medium to which the pretreatment solution 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 where productivity is paramount. Furthermore, according to the present invention, it is possible to switch between high-quality printing and high-productivity printing depending on the application, making it possible to manufacture not only printed materials where image quality is paramount, but also printed materials where productivity is paramount. [Brief explanation of the drawing]

[0032] [Figure 1] Figure 1 is an overall configuration diagram of an inkjet printing apparatus according to an embodiment of the present invention. [Figure 2] Figure 2 is a side view showing an overview of the ink drying section in an inkjet printing apparatus. [Figure 3] Figure 3 is a functional block diagram showing the schematic configuration of the control system of an inkjet printing apparatus. [Figure 4] Figure 4 is a diagram showing examples of combinations of print resolution, maximum ink droplet volume, and drying intensity settings for standard mode and high-speed mode, respectively. [Figure 5] Figure 5 is a diagram showing an example of the settings for the drying conditions table. [Figure 6] Figure 6 is a flowchart showing an example of control when changing the transport speed. [Figure 7] Figure 7 is a chart showing the evaluation results of the film strength of the printed surface when the combination of transport speed and drying strength conditions was changed when using the cardboard paper according to Example 1. [Figure 8] Figure 8 is a chart showing the evaluation results of the film strength of the printed surface when the combination of transport speed and drying strength conditions was changed when using thin paper according to Example 2. [Figure 9] Figure 9 is a perspective view of an inkjet print head. [Figure 10] Figure 10 is a magnified view of the inkjet head as seen from the nozzle side. [Figure 11] Figure 11 is a plan view of the nozzle surface of the head module as seen from the discharge side. [Figure 12] Figure 12 is a longitudinal cross-sectional view showing the three-dimensional structure of a single ejector in the head module. [Modes for carrying out the invention]

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

[0034] Configuration of an inkjet printing device Figure 1 is an overall configuration diagram of an inkjet printing apparatus 1 according to an embodiment of the present invention. The inkjet printing apparatus 1 is an inkjet-type color digital printing apparatus that uses four inks, cyan (C), magenta (M), yellow (Y), and black (K), to print a desired image on a sheet of paper P in a single-pass manner. The inkjet printing apparatus 1 is an example of an "image forming apparatus" in this disclosure. In this embodiment, an example in which aqueous ink is used as the ink for drawing will be described. Aqueous ink refers to an ink in which a coloring material such as a pigment or dye is dissolved or dispersed in water and / or a water-soluble solvent.

[0035] The inkjet printing apparatus 1 comprises a paper feeding unit 10, a processing liquid application unit 20, a processing liquid drying unit 30, a drawing unit 40, an ink drying unit 50, and an accumulation unit 60.

[0036] The paper feeding unit 10 comprises a paper feeding device 12, a feeder board 14, and a paper feeding drum 16. Paper P is placed on the paper feeding tray 12A in a stack of multiple sheets. The type of paper P is not particularly limited, but printing papers mainly composed of cellulose, such as fine paper, coated paper, and art paper, can be used. The maximum paper size that can be used in the inkjet printer 1 is, for example, 750 mm x 585 mm.

[0037] The paper feeder 12 takes out one sheet of paper P from the stack set on the paper feed tray 12A, starting from the top, and supplies it to the feeder board 14. The feeder board 14 then transports the paper 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 processing liquid application unit 20.

[0039] The processing liquid application unit 20 applies the processing liquid to the paper P. The term "processing liquid" is synonymous with "pre-treatment liquid." The processing liquid may also be called "pre-coat," "pre-conditioner," "undercoat liquid," or "processing agent." The processing liquid is a liquid that has the function of coagulating, insolubilizing, or thickening the colorant components in the ink. The processing liquid application unit 20 comprises a processing liquid application drum 22 and a processing liquid application device 24.

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

[0041] The processing liquid coating device 24 is equipped with a coating roller 25 and applies the processing liquid to the paper P conveyed by the processing liquid coating drum 22. The coating roller 25 is supported by a contact / separation mechanism (not shown) that can move between a coating position in contact with the paper P to apply the processing liquid to the paper P and a retracted position away from the paper P to not apply the processing liquid. The function of applying the processing liquid to the paper P using the processing liquid coating device 24 is called the "pre-coat function". The processing liquid coating device 24 is an example of a "coating device" in this disclosure.

[0042] The inkjet printing device 1 can selectively turn the pre-coat function ON / OFF. When the pre-coat function is ON, the coating roller 25 is controlled to the coating position, and when the pre-coat function is OFF, the coating roller 25 is controlled to the retracted position.

[0043] The area to which the processing liquid is applied to the paper P may be the entire surface of the paper P, or it may be partially applied to the area where ink is applied in the drawing section 40. From the viewpoint of uniformly adjusting the amount of processing liquid applied, uniformly recording fine lines and fine image parts, and suppressing density unevenness such as image unevenness, it is preferable to apply the processing liquid to the entire image-forming surface of the paper P by coating with a coating roller or the like.

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

[0045] The processing liquid drying unit 30 dries the paper P to which the processing liquid has been applied. The processing liquid drying unit 30 comprises a processing liquid drying drum 32 and a hot air blower 34. The processing liquid drying drum 32 receives the paper P from the processing liquid application drum 22 and transports the received paper P to the drawing unit 40. The processing liquid drying drum 32 is equipped with a gripper 33 on its circumferential surface. The processing liquid drying drum 32 transports the paper P by gripping the leading edge of the paper P with the gripper 33 and rotating it.

[0046] The hot air blower 34 is installed inside the processing liquid drying drum 32. The hot air blower 34 blows hot air onto the paper P being transported by the processing liquid drying drum 32 to dry the processing liquid.

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

[0048] The head unit 44 comprises inkjet heads 46C, 46M, 46Y, and 46K. Inkjet head 46C is a recording head that ejects droplets of cyan ink. Inkjet head 46M is a recording head that ejects droplets of magenta ink. Inkjet head 46Y is a recording head that ejects droplets of yellow ink. 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 source for the corresponding color, via a piping route (not shown).

[0049] Each of the inkjet heads 46C, 46M, 46Y, and 46K is a line head capable of printing on the paper P transported by the drawing drum 42 in a single scan, i.e., in a single-pass manner. The nozzle surfaces of the inkjet heads 46C, 46M, 46Y, and 46K are positioned facing the circumferential surface of the drawing drum 42. The inkjet heads 46C, 46M, 46Y, and 46K are positioned at regular intervals along the transport path of the paper P by the drawing drum 42.

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

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

[0052] The specified print resolution may be a print resolution predetermined by the inkjet printer 1, or it may be a print resolution set by user selection or by automatic selection by a program according to the print mode. For example, the print resolution can be 1200 dpi in the X direction and 1200 dpi in the Y direction. "dpi" stands for dots per inch and is a unit that represents the number of dots (points) per inch. One inch is 25.4 millimeters [mm].

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

[0054] In the case of an inkjet head with a two-dimensional nozzle array, the projected nozzle array, obtained by projecting (orthogonally projecting) each nozzle in the two-dimensional nozzle array so that they are aligned along the nozzle row direction, can be considered equivalent to a single row of nozzles arranged at approximately equal intervals with a nozzle density that achieves the maximum recording resolution in the nozzle row direction. "Approximately equal intervals" means that the droplet points that can be recorded by the inkjet printing device are substantially equally spaced. For example, even if there are some nozzles with slightly different spacing to account for manufacturing errors and / or droplet movement on the medium due to impact interference, the concept of "equal intervals" is still included. The projected nozzle array corresponds to the actual nozzle array. When considering the projected nozzle array, a nozzle number representing the nozzle position can be associated with each nozzle in the order of the projected nozzles arranged along the nozzle row direction.

[0055] The nozzle arrangement configuration for each of the inkjet heads 46C, 46M, 46Y, and 46K is not limited, and various nozzle arrangement configurations can be adopted. For example, instead of a matrix-like two-dimensional arrangement, a single-line arrangement, a V-shaped nozzle arrangement, or a bent-line nozzle arrangement such as a W-shape with repeating V-shaped arrangements are also possible.

[0056] At least one of the inkjet heads 46C, 46M, 46Y, and 46K is ejected from the inkjet head towards the paper P being transported by the drawing drum 42, and an image is formed on the paper P when the ejected droplet adheres to the paper P.

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

[0058] In this example, a configuration using four CMYK inks is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light inks, dark inks, spot inks, etc. may be added as needed. For example, it is possible to add an inkjet head that ejects light inks such as light cyan and light magenta, and / or an inkjet head that ejects a spot ink such as green, orange, or white. Furthermore, there are no particular limitations on the arrangement order of the inkjet heads for each color.

[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 include an illumination optical system that illuminates the object to be read and a signal processing circuit that processes the signals obtained from the imaging device to generate digital image data.

[0060] The image reading device 48 is preferably configured to read color images. In this example, the image reading device 48 uses, for example, a color CCD (Charge-Coupled Device) linear image sensor as the imaging device. A color CCD linear image sensor is an image sensor in which light-receiving elements equipped with R (red), G (green), and B (blue) color filters are arranged in a linear fashion. Alternatively, a color CMOS (Complementary Metal Oxide Semiconductor) linear image sensor can be used instead of a 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 drawing drum 42. An image reading device installed in this way along the paper transport path is sometimes called an "inline scanner" or "inline sensor". The image reading device 48 may also be a camera.

[0061] When a sheet of 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 reader 48, the image on the sheet of paper P is read. The image recorded on the sheet of 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 checking the ejection state of each nozzle, a test pattern for correcting print density, a test pattern for correcting print density unevenness, and various other test patterns.

[0062] Based on the data of the image read by the image reading device 48, the printed image is inspected to determine whether or not there are any abnormalities in image quality. In addition, based on the data of the image read by the image reading device 48, information such as the image density 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 unit 90.

[0064] The chain gripper 70 receives the paper P from the drawing drum 42 and transports the received paper P to the stacking unit 60. The chain gripper 70 is equipped with a pair of endless chains 72 that travel along a predetermined path, and the leading edge of the paper P is gripped by grippers 74 provided on the pair of chains 72, and the paper P is transported along the predetermined transport path. Multiple grippers 74 are provided on the chains 72 at regular intervals.

[0065] The chain gripper 70 in this example is composed of 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 are wrapped around a pair of first sprockets 71A and second sprockets 71B. Figure 1 shows only one of the pair of first sprockets 71A and second sprockets 71B and the pair of chains 72.

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

[0067] The transport path for the paper P by the chain gripper 70 includes a horizontal transport area that transports the paper P horizontally and an inclined transport area that transports the paper P 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 consists of a first paper guide 82 and a second paper guide 84. The first paper guide 82 guides the paper P being transported in the first transport section of the chain gripper 70. The second paper guide 84 guides the paper being transported in the second transport section, which is after the first transport section.

[0069] Although the detailed structure of the first paper guide 82 is not shown in Figure 1, a suction transport device 102 is used as the first paper guide 82 (see Figure 2). A detailed explanation of the configuration of the suction transport device 102 will be given later.

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

[0071] The stacking unit 60 includes a stacking device 62 that receives the paper P transported from the ink drying unit 50 by the chain gripper 70 and stacks it. The chain gripper 70 releases the paper P at a predetermined stacking position. The stacking device 62 includes a stacking tray 62A, which receives the paper P released from the chain gripper 70 and stacks it in bundles on the stacking tray 62A. The stacking unit 60 corresponds to the paper discharge unit.

[0072] 《Overview of the ink drying section 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 identical to those shown in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted. For the sake of simplicity, the image reading device 48, the first sprocket 71A, and the second sprocket 71B are omitted from the illustration in Figure 2.

[0073] The ink drying unit 50 includes a heating and drying unit 90 and an adsorption conveying device 102. The heating and drying unit 90 includes, for example, an infrared lamp (not shown) as a heat source and an air blower (not shown). The adsorption conveying 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. The belt 110 has multiple suction holes for adsorbing 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 counterclockwise in Figure 2. As the drive roller 112 rotates, the belt 110 moves in a counterclockwise direction in Figure 2. The driven roller 114 rotates counterclockwise in Figure 2, following the belt 110. In Figure 2, the direction in which the belt 110 moves from the driven roller 114 toward the drive roller 112 corresponds to the direction in which the paper P is transported.

[0076] The belt 110 has a width in the X direction that is greater than the width of the paper P in the X direction. The belt 110 supports the paper P that is conveyed by the chain gripper 70 and conveys the paper P.

[0077] The outer circumferential surface of the belt 110 stretched between the drive roller 112 and the driven roller 114 is called the first surface of the belt 110. The surface opposite to the first surface of the belt 110, that is, the inner circumferential surface of the belt 110 wrapped around the drive roller 112 and the driven roller 114, is called the second surface of the belt 110. The second surface is sometimes referred to as the "back side" of the belt 110.

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

[0079] In Figure 2, the region of the belt 110's circumference path where the belt 110 moves from the driven roller 114 toward the driven roller 112, i.e., the upper belt path in Figure 2, is called the first belt path. The region of the belt 110's circumference path where the belt 110 moves from the driven roller 112 toward the driven roller 114, i.e., the lower belt path in Figure 2, is called the second belt path. The second belt path is the return belt path. In this example, the conveying surface 110A is a plane parallel to the horizontal plane, but the conveying surface 110A may be an inclined surface having an angle that intersects with the horizontal plane. For example, the second paper guide 84 may have the same configuration as the suction conveying device 102.

[0080] The suction box 116 is positioned on the second side of the belt 110, that is, on the back 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 at the suction holes of the belt 110. In the first belt path, the area on the back side of the belt 110 where the suction box 116 is positioned becomes the suction area for suction and adsorption of the paper P. The suction box 116 may be divided (separated) into multiple areas in the Y direction.

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

[0082] The infrared lamps 162 and 164 heat the drive roller 112 and the driven roller 114, which indirectly heats the belt 110. By preheating the belt 110, the drying process can be performed efficiently in conjunction with the heating and drying process by the heating and drying unit 90.

[0083] The paper P on which the 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 being grasped by the gripper 74, it is placed on the belt 110 and attached to the belt 110.

[0084] The chain gripper 70 transports the gripper 74 in synchronization with the rotational speed of the drawing drum 42. The drive roller 112 is rotationally driven to move the belt 110 in accordance with the feed rate 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 rates of the belt 110 and the gripper 74 do not necessarily need to be exactly the same; a slight difference in speed is acceptable.

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

[0087] The belt 110 has a length that allows it to simultaneously suction and transport multiple sheets of paper P. The belt 110 shown in Figure 2 has a length that allows it to simultaneously suction and transport two sheets of paper P, but the length of the belt 110 can be designed as appropriate, and a configuration that allows it to simultaneously suction and transport three or more sheets of paper P is also possible. As an example of dimensions, for example, the distance between the drive roller 112 and the driven roller 114 may be 1250 mm, and the suction distance of the suction box 116 may be 1000 mm.

[0088] 《Overview of the control system of inkjet printing device 1》 Figure 3 is a functional block diagram showing the schematic configuration of the control system of the inkjet printing apparatus 1. The inkjet printing apparatus 1 comprises 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 control unit that performs various processes by executing program instructions stored in the storage device 302. The processor 300 functions as a system control unit 310, an image processing unit 311, a transport control unit 312, a paper feed control unit 313, a processing liquid application control unit 314, a processing 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 implemented using multiple processors. Furthermore, some of the processing functions necessary for processing and / or control may be implemented 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-temporary, tangible, computer-readable medium. The storage device 302 includes memory, which is the main memory, and storage, which is the auxiliary storage. The storage device 302 may be, for example, semiconductor memory, a hard disk drive (HDD), or a solid state drive (SSD), or a combination of these. 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 types of data, including image data.

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

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

[0094] The system control unit 310 functions as an overall control unit that comprehensively controls each part of the inkjet printing apparatus 1. Furthermore, the system control unit 310 functions as an arithmetic unit that performs various calculations. In addition, the system control unit 310 controls the reading and writing of data to the storage device 302.

[0095] The communication unit 304 is equipped with the necessary communication interface. The inkjet printer 1 is connected to the host computer 400 via the communication unit 304 and can send and receive data with the host computer 400. The term "connection" here includes wired connections, wireless connections, or a combination thereof. The communication unit 304 may be equipped with a buffer memory to speed up communication processing. The communication unit 304 also functions as an image input interface unit for acquiring image data representing the image to be printed. 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 and correction processes, as well as halftone processing, on the image data to be printed. Conversion processes include pixel count conversion, gradation conversion, and color conversion. Correction processes include density correction and non-ejection correction to suppress the visibility of image defects caused by faulty nozzles. The image processing unit 311 performs correction processing based on the image read by the image reading device 48. Halftone processing is generally a process of quantizing multi-gradation image data with m values ​​(where m is an integer of 3 or more) and converting it into n-value data (where n is an integer of 2 or more and less than m). For example, the image processing unit 311 converts the 8-bit (256 gradations) image signals for each CMYK color into signals (dot data) that represent the arrangement of dots with three or more 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 produce three different droplet sizes (dot sizes): small, medium, and large, the image processing unit 311 converts the 8-bit color separation image data into a signal with four gradations (N=4): "eject large droplet ink," "eject medium droplet ink," "eject small droplet ink," and "do not eject (no droplet)." For such halftone processing, methods such as dithering or error diffusion may be applied.

[0098] The transport control unit 312 controls the operation of the transport mechanism 11. The transport mechanism 11 includes the elements of the mechanism involved in the transport of paper P from the paper feeding unit 10 to the stacking unit 60, as described in Figure 1. The transport mechanism 11 includes the paper feeding drum 16, processing liquid coating drum 22, processing liquid drying drum 32, drawing drum 42, and chain gripper 70 shown in Figure 1. The transport mechanism 11 also includes a drive unit such as a motor (not shown) and a motor drive circuit (not shown) as a power source. The transport control unit 312 controls the transport speed of paper P by the transport mechanism 11 in response to commands from the system control unit 310, and controls the transport of paper P from the paper feeding unit 10 to the stacking unit 60.

[0099] The paper feed control unit 313 operates the paper feed unit 10 in response to commands from the system control unit 310. The paper feed control unit 313 controls the start and stop operations of paper supply P.

[0100] The processing liquid application control unit 314 operates the processing liquid application unit 20 in response to commands from the system control unit 310. The processing liquid application control unit 314 controls the application operation of the processing liquid application device 24, including turning the pre-coat function ON / OFF, the amount of processing liquid applied, and the timing of application.

[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 the drying gas injection.

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

[0104] Furthermore, the drawing control unit 318 can output predetermined command signals to each inkjet head 46C, 46M, 46Y, and 46K to check the nozzle status and control the printing of nozzle status evaluation patterns.

[0105] The ink drying control unit 320 operates the ink drying unit 50 in response to commands from the system control unit 310. The ink drying control unit 320 controls the drying gas temperature, the drying gas flow rate, and the drying gas injection timing, etc.

[0106] The paper output control unit 324 operates the stacking unit 60 in response to commands from the system control unit 310. When the stacking device 62 shown in Figure 1 includes a lifting mechanism, the paper output control unit 324 controls the operation of the lifting mechanism in accordance with the increase or decrease in the amount of paper P.

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

[0108] Information input via the input device 306 is sent to the system control unit 310. The system control unit 310 performs various processes according to the information input from the input device 306.

[0109] The display device 308 can display various information, such as various device settings or abnormal information, in response to commands from the system control unit 310. The user (operator) can set various parameters and input and edit various information using the input device 306 while viewing the contents displayed on the display device 308.

[0110] 《Overview of the operation of inkjet printing device 1》 The inkjet printer 1 is configured to enable both high-quality printing and high-productivity printing in a single device. It has a standard mode that transports paper at a standard transport speed prioritizing high image quality, and a high-speed mode for improving productivity, and these modes can be selectively switched between. The high-speed mode is a mode that transports paper at a speed faster than the standard transport speed, prioritizing productivity, and multiple modes with different transport speeds may be provided.

[0111] Here, as a specific example, we will illustrate a configuration where the standard transport speed in standard mode is 3600 sph, and two transport speeds, 5400 sph and 7200 sph, are available for high-speed mode, with the option to select either one. Note that "sph" is a unit representing the number of sheets printed 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 rephrased as the "high-quality mode," and the high-speed mode as the "high-productivity mode." These modes with different transport speeds may be understood as types of transport modes or types of printing modes. The standard mode is an example of the "first mode" in this disclosure. The high-speed mode is an example of the "second mode" in this disclosure. 3600 sph is an example of the "first transport speed" in this disclosure. 5400 sph and 7200 sph are examples of the "second transport speed" in this disclosure, respectively. In this embodiment, an example is shown in which the transport speed of the high-speed mode is set to 1.5 to 2 times the standard transport speed, but the transport speeds in each of the standard mode and high-speed mode can be set as appropriate. Preferably, the transport speed of the high-speed mode is set to 1.2 times or more the standard transport speed.

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

[0114] Furthermore, when the inkjet printer 1 switches to high-speed mode, the function for applying the processing liquid (pre-coat function) is turned OFF, and printing is performed as a one-liquid agglomeration system. When standard mode is selected, the pre-coat function is turned ON, and the inkjet printer 1 performs printing as a two-liquid agglomeration system. In other words, with the pre-coat function ON (standard mode), the coating roller 25 repeatedly makes contact with and separates from each sheet of paper P, transferring the processing liquid to the paper P. On the other hand, with the pre-coat function OFF (high-speed mode), the coating roller 25 is kept in a separated state at all times, and no coating is performed. With this configuration, it is possible to switch between a one-liquid agglomeration system configuration and a two-liquid agglomeration system configuration without changing the transport path of the paper P.

[0115] Furthermore, the inkjet printing apparatus 1 changes the drying intensity in the ink drying section 50 in accordance with the change in transport speed. The drying function of the drying apparatus, which includes the heating and drying section 90 located downstream of the drawing section 40 and infrared lamps 162 and 164, may result in insufficient drying if the drying process is the same as in the standard mode due to the increased paper transport speed. Insufficient drying can cause, for example, curling, worsening of cuckle, worsening of blocking, and reduced film durability. For this reason, in conjunction with switching to high-speed mode, the inkjet printing apparatus 1 also changes the drying intensity of the drying apparatus to a table of drying conditions corresponding to high-speed mode, and the drying intensity is increased compared to the standard mode.

[0116] When printing in high-speed mode, it is preferable to strengthen the drying strength of the ink drying unit 50. However, by combining a reduction in the maximum ejected ink droplet volume with a reduction in print resolution, it is possible to minimize the increase in drying strength. Specifically, while the maximum ejected ink droplet volume in standard mode is 4.5 pl to 5.5 pl, in high-speed mode, reducing the maximum ejected ink droplet volume to 2.5 pl to 3.5 pl reduces the total amount of ink applied to the paper P, thereby reducing the required drying capacity. The maximum ejected ink droplet volume is the maximum amount of ink ejected to form one dot by each of the inkjet heads 46C, 46M, 46Y, and 46K, and represents the maximum amount of ink droplets per dot ejected from each head. To change the maximum ejected ink droplet volume, for example, the amount of large droplets may be changed, or the amount of medium droplets may be set as the "maximum ejected ink droplet volume" by not using large droplets.

[0117] Furthermore, regarding the print resolution, while the standard mode uses a resolution of, for example, 1200 dpi × 1200 dpi, the high-speed mode switches to, for example, 1200 dpi × 600 dpi by reducing the resolution in the Y direction. This reduces the total amount of ink used, making it possible to lower the required drying capacity. 1200 dpi × 1200 dpi is an example of the "first print resolution" in this disclosure. 1200 dpi × 600 dpi is an example of the "second print resolution" in this disclosure.

[0118] Figure 4 is a diagram showing examples of combinations of settings for print resolution, maximum ink droplet volume, and drying intensity for the standard mode and high-speed mode, respectively. In high-speed mode, by increasing the drying intensity compared to the standard mode in conjunction with at least one of the following processes—reduction of maximum ink droplet volume and reduction of print resolution—insufficient drying can be suppressed, and it becomes possible to maintain print performance such as curl, cuckle, and film quality performance equivalent to that of the standard mode.

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

[0120] Figure 5 is a diagram showing an example of setting the drying conditions table. Figure 5 shows an example of setting the drying temperature for each paper thickness range for gloss coated paper. In Figure 5, "hot air temperature" is the temperature of the hot air blown out from the heating and drying processing unit 90. "Belt temperature" is the temperature of the belt 110 of the suction conveying device 102. Since the drying process is carried out by hot air 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, both temperature settings are necessary. Although not shown in Figure 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 conditions table and sets the temperature according to the paper type and paper thickness of the paper P used.

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

[0122] The relationship between print quality and transport speed. In high-speed mode, the processing solution is not applied, and furthermore, the print resolution is reduced, which may result in lower print quality compared to standard mode. In high-speed mode, the absence of a pre-coat (single-component agglomeration system) increases the ink dot diameter compared to standard mode, which may worsen granularity and / or boundary reproduction (color bleeding) compared to standard mode.

[0123] Furthermore, the high-speed mode is expected to worsen character and line reproduction quality by reducing the print resolution compared to the standard mode. Depending on the printing application, users should use the high-speed mode for print jobs where high productivity is required even if it means lower image quality, and the standard mode for print jobs where image quality is important. High-speed mode improves productivity, making it possible to increase productivity by 1.5 times with the 5400sph compared to the standard mode (3600sph), and by 2 times with the 7200sph.

[0124] [Example of printing operation in inkjet printer 1] Figure 6 is a flowchart illustrating an example of printing operation in the inkjet printer 1. Figure 6 shows an example of control when changing the transport speed. In step S11, the processor 300 receives input for specifying the transport mode. For example, the processor 300 receives input from the input device 306 specifying either standard mode or high-speed mode. Alternatively, the processor 300 may, according to program instructions, set standard mode as the default setting and accept instructions to change to high-speed mode via the input device 306.

[0125] In step S12, the processor 300 determines whether the specified mode is standard mode or high-speed mode. If the result of the determination in step S12 is "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. The standard transport speed may be, for example, 3600 sph.

[0127] Next, in step S14, the processor 300 turns on the pre-coat function. As a result, the inkjet printing apparatus 1 functions as a two-component agglomeration system apparatus.

[0128] Next, in step S15, the processor 300 sets the print resolution to the standard print resolution. The standard print resolution may be, for example, 1200 dpi × 1200 dpi.

[0129] Next, in step S16, the processor 300 sets the maximum ink droplet volume to a standard value. The standard value of the maximum ink droplet volume may be, for example, a value within the range of 4.5 pl or more and 5.5 pl or less. 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 intensity of the ink drying unit 50 to the standard drying intensity. The drying conditions for the standard drying intensity, and the drying conditions for the high drying intensity (described later), are stored in the storage device 302 as table data in advance, according to the type and thickness of the paper P used for printing. The processor 300 can read the drying conditions that match the type and thickness of the paper P used from the table data. The information on the type and thickness of the paper P may be input from the input device 306, or it may be input using a barcode reader or the like (not shown). After step S17, the processor 300 proceeds to step S30. The order of processing in steps S13 to S17 can be changed as appropriate.

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

[0132] In step S23, the processor 300 sets the transport speed to the high-speed transport speed. The high-speed transport speed 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-coat function. As a result, the inkjet printing apparatus 1 functions as a one-liquid agglomeration system apparatus. When the pre-coat function is turned off, the drying process in the processing liquid drying section 30 is also turned off.

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

[0135] Next, in step S26, the 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 only needs to be a small amount less than the standard value, and may be a value determined within the range of 2.5 pl or more and 3.5 pl or less. 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 intensity of the ink drying unit 50 to a high drying intensity, which is higher than the standard drying intensity. After step S27, the processor 300 proceeds to step S30. Note that the order of processing in steps S23 to S27 can be changed as appropriate.

[0137] In step S30, the processor 300 accepts the selection of a print job. Once the print job to be processed is specified based on user input or other means, in step S32, the processor 300 determines whether or not to change the drying intensity.

[0138] If the result of 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 modifies (changes) the drying intensity setting according to the image content of the print target specified in the print job. This is a process that evaluates the total amount of ink from the print target image and changes 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. Also, if the result of the determination in step S32 is NO, the processor 300 proceeds to step S34.

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

[0141] Example 1 The following describes the evaluation results of the film quality performance (film strength) of the printed surface when the combination of transport speed and drying strength conditions was changed, using a specific brand of paper P. In Example 1, paper P was "Ibest" (registered trademark: Nippon Paper Industries Co., Ltd.) with a basis weight of 310 gsm (paper thickness of 0.34 mm), and the film quality strength was evaluated when the combination of transport speed and drying strength conditions was changed. Example 1 corresponds to the performance evaluation of so-called "thick paper". Figure 7 shows the evaluation results. Note that the basis weight is the manufacturer's nominal value, and the unit gsm is "g / m²". 2 "

[0142] Film strength is one of the indicators that represents the hardness of the coating on a printed surface. Film strength was measured using a "pendulum-type hardness tester" on paper P immediately after printing, drying, and ejection.

[0143] Film strength is one of the properties that can be used as a substitute for blocking performance and / or film performance. Blocking refers to the peeling of printed surfaces due to overlapping of printed materials. Film performance refers to properties such as 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. For the other symbols "A+", "B", "C", "D", etc., based on the symbol A, they show 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 carried out with a maximum ejected ink droplet volume of 5 pl and a printing resolution set at 1200 dpi × 1200 dpi. At conveyance speeds of 5400 sph and 7200 sph, printing is carried out with a maximum ejected ink droplet volume of 3.5 pl and a printing resolution set at 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, showing 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, showing 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 by increasing the conveyance speed while maintaining the standard drying strength, the film quality strength deteriorates, 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] It should be noted that these results were obtained when the maximum ink droplet volume was the same, and it has been confirmed that film quality improves by reducing the maximum ink droplet volume. Furthermore, regarding other print quality performance characteristics such as curl and cuckle, the results showed that there was almost no effect from increased transport speed and increased drying strength at iBEST (registered trademark: Nippon Paper Industries Co., Ltd.) 310gsm basis weight.

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

[0151] In Example 2, the drying conditions for standard drying strength were a hot air temperature of 100°C and a belt temperature of 90°C. In Example 2, the drying conditions for high drying strength were a hot air temperature of 110°C and a belt temperature of 100°C. For "OK ​​Topcoat+" with a basis weight of 104 gsm, increasing the conveying speed while maintaining standard drying strength deteriorates the film quality, but not to the extreme degree seen with Ibest® (registered trademark) with a basis weight of 310 gsm. At 5400 sph, the film quality remains almost unchanged, and only slightly deteriorates at 7200 sph. Therefore, by slightly increasing the drying strength above the standard drying strength, it is possible to maintain film quality above the product specification level.

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

[0153] Regarding 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 (single-component agglomeration system) and standard mode (two-component agglomeration system). By using the same ink for both standard mode and high-speed mode printing, the ink does not need to be changed for each transport speed, thus eliminating waste when switching transport speeds. This improves overall productivity when performing printing for multiple purposes while switching transport modes.

[0154] Examples of processing solutions The processing solution used in this embodiment contains a component (aggregation-inducing component) that, upon contact with the CMYK ink compositions, aggregates the components in the ink compositions, forming aggregates containing pigments. Examples of this aggregation-inducing component include components selected from acidic compounds, polyvalent metal salts, and cationic polymers. In addition to the aggregation-inducing component, the processing solution may contain other components as needed. The processing solution is usually in the form of an aqueous solution. By using the processing solution together with the ink composition, inkjet printing can be accelerated, and even at high speeds, images with high density, high resolution, and excellent reproducibility of fine lines and fine details can be obtained.

[0155] <Acidic compounds> Acidic compounds can coagulate (immobilize) components in an ink composition by coming into contact with it on a recording medium, and thus function as immobilizing agents. Examples of acidic compounds 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, pyrrolidone carboxylic acid, pyrrone carboxylic acid, pyrrole carboxylic acid, furanic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, oxalic acid, and benzoic acid. From the viewpoint of achieving both suppression of volatilization and solubility in the solvent, the acidic compound is preferably an acid with a molecular weight of 35 to 1000, more preferably an acid with a molecular weight of 50 to 500, and particularly preferably an acid with a molecular weight of 50 to 200. Furthermore, regarding the acid dissociation constant pKa (in H2O, 25℃), from the viewpoint of achieving both ink bleeding prevention and photocurability, an acid between -10 and 7 is preferred, an acid between 1 and 7 is more preferred, and an acid between 1 and 5 is particularly preferred.

[0156] Among these, highly water-soluble acidic compounds are preferred. Furthermore, from the viewpoint of reacting with the ink composition to immobilize the entire ink, trivalent or less acidic compounds are preferred, and divalent or trivalent acidic compounds are particularly preferred. The treatment solution may use one acidic compound alone, or two or more may be used in combination.

[0157] If the treatment solution is an aqueous solution containing an acidic compound, the pH (at 25°C) of the treatment solution 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 solution contains an acidic compound as a coagulation component, the content of the acidic compound in the treatment agent is preferably 40% by mass or less, more preferably 15-40% by mass, even more preferably 15-35% by mass, and particularly preferably 20-30% by mass. By setting the content of the acidic compound in the treatment agent to 15-40% by mass, the components in the aqueous ink composition can be immobilized more efficiently.

[0159] When the processing solution contains an acidic compound as an agglomeration-inducing component, there are no particular restrictions on the amount of the processing solution applied to the recording medium, as long as it is sufficient to agglomerate the ink composition. However, from the viewpoint of facilitating the immobilization of the ink composition, applying an acidic compound of 0.5 g / m² is recommended. 2 ~4.0g / m 2 It is preferable to apply the treatment agent in such a manner that the following occurs: 0.9 g / m 2 ~3.75g / m 2 It is preferable to apply the treatment agent in such a manner.

[0160] <Polyvalent metal salts> The treatment solution may also contain one or more polyvalent metal salts as flocculation-inducing components. Including polyvalent metal salts as flocculation-inducing components can improve high-speed flocculation. Examples of polyvalent metal salts include salts of alkaline earth metals from Group 2 of the periodic table (e.g., magnesium, calcium), salts of transition metals from Group 3 of the periodic table (e.g., lanthanum), salts of cations from Group 13 of the periodic table (e.g., aluminum), and salts of lanthanides (e.g., neodymium). Suitable metal salts include carboxylates (e.g., formic acid, acetic acid, benzoates), nitrates, chlorides, and thiocyanates. Among these, calcium or magnesium salts of carboxylic acids (e.g., formic acid, acetic acid, benzoates), calcium or magnesium salts of nitrates, calcium chloride, magnesium chloride, and calcium or magnesium salts of thiocyanate are preferred.

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

[0162] <Cationic polymers> Furthermore, the treatment solution may preferably contain one or more cationic polymers as flocculation-inducing components. The cationic polymers are preferably homopolymers of cationic monomers having primary to tertiary amino groups or quaternary ammonium bases as cationic groups, or copolymers or condensation polymers of these cationic monomers and non-cationic monomers. The cationic polymer may be used in the form of a water-soluble polymer or water-dispersible latex particles.

[0163] Preferred specific examples of cationic polymers include poly(vinylpyridine) salts, polyalkylaminoethyl acrylates, polyalkylaminoethyl methacrylates, poly(vinylimidazole), polyethyleneimine, polybiguanide, polyguanide, or polyallylamine and its derivatives. From the viewpoint of viscosity of the treatment solution, a smaller weight-average molecular weight of the cationic polymer is preferable. From the viewpoint of flocculation induction effect, the content of the cationic polymer in the treatment solution is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and even more preferably in the range of 2 to 20% by mass.

[0164] <Other additives> The treatment solution may contain other additives as additional components, provided that they do not impair the desired flocculation effect. Examples of other known additives include drying inhibitors (wetting agents), colorfastness inhibitors, emulsifying stabilizers, penetration enhancers, UV absorbers, preservatives, fungicides, pH adjusters, surface tension adjusters, defoamers, viscosity modifiers, dispersants, dispersion stabilizers, rust inhibitors, and chelating agents.

[0165] Examples of inkjet head configurations Since the structure of inkjet heads 46K, 46C, 46M, and 46Y is the same, we will refer to them as inkjet head 46 in this explanation.

[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 a diagonal downward direction. The inkjet head 46 is a full-line type line head, which is elongated by arranging multiple head modules 212 in the paper width direction.

[0167] Figure 9 shows an example of 17 head modules 212 connected together, but the structure of the head modules 212, the number of head modules 212, and the arrangement are not limited to the example shown. Reference numeral 214 in the figure indicates a base frame that serves as a frame for connecting and fixing multiple head modules 212 in a bar shape. Reference numeral 216 indicates a flexible circuit board connected to each head module 212. Multiple head modules 212 are mounted on 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 seen from the nozzle side. The head module 212 is supported by module support members 218B from both sides in the vertical direction of Figure 10, which is the short side 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 Figure 10, the diagonal solid line denoted by reference numeral 224A represents a nozzle row in which multiple nozzles are arranged in a single line.

[0170] Figure 11 is a plan view of the nozzle surface 212A of the head module 212 as seen from the discharge side. For illustrative purposes, Figure 11 shows a reduced number of nozzles, but the nozzle surface 212A of a single head module 212 has, for example, 32 × 64 nozzles 220 arranged in two dimensions. In addition, a liquid-repellent film is formed on the nozzle surface 212A.

[0171] In Figure 11, the Y direction is the paper transport direction, and the X direction, which is perpendicular to the Y direction, is the paper width direction. The head module 212 has an end face on the longer side along the V direction with an inclination of angle γ with respect to the X direction, and an end face on the shorter side along the W direction with an inclination of angle α with respect to the Y direction, and has a parallelogram shape in plan view.

[0172] By connecting multiple such head modules 212 in the X direction, a nozzle array is formed that covers the entire drawing area of ​​the paper P in the X direction, creating a line head capable of recording an image at a specified recording resolution in a single drawing scan. Note that a full-line type line head applied to a single-pass method is not limited to cases where the entire surface of the paper P (the recording medium) is the printing area; even when only a portion of the recording medium is the printing area (for example, when a margin is provided around the recording medium), it is sufficient to have the necessary nozzle array for printing.

[0173] Figure 12 is a longitudinal cross-sectional view showing the three-dimensional structure of one ejector 222 in the head module 212. The ejector 222 comprises a nozzle 220, a pressure chamber 250 leading to the nozzle 220, and a piezoelectric element 252. The nozzle 220 is connected to the pressure chamber 250 via a nozzle flow path 254. The pressure chamber 250 is connected to a common supply flow path 226 via an individual supply path 224.

[0174] The diaphragm 256, which 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, as well as the diaphragm 256, can be made of silicon. The material of the diaphragm 256 is not limited to silicon; it can also be formed from a non-conductive material such as resin. A conductive layer made of a conductive material is formed on the surface of the diaphragm member. The diaphragm 256 itself may be made of a metal material such as stainless steel and may also serve as a diaphragm that doubles as a common electrode.

[0175] A piezoelectric unimorph actuator is constructed by stacking piezoelectric elements 252 on a diaphragm 256. By applying a driving voltage to the individual electrodes 258, which are the upper electrodes of the piezoelectric elements 252, the piezoelectric body 260 is deformed, causing the diaphragm 256 to flex and changing the volume of the pressure chamber 250. This change in volume and the resulting pressure change causes ink to be ejected from the nozzle 220. When the piezoelectric element 252 returns to its original state after ink ejection, new ink is filled into the pressure chamber 250 from the supply-side common flow path 226 through the individual supply path 224. The operation of filling the pressure chamber 250 with ink is called "refilling". In this example, a configuration is shown that uses the d31 mode strain deformation of the piezoelectric body 260 to flex the diaphragm 256, but configurations that use the d33 mode or the shear mode (shear deformation) to perform ejection are also possible.

[0176] There are no particular limitations on the planar shape of the pressure chamber 250; it can take various forms, such as a square, other polygons, a circle, or an ellipse.

[0177] Furthermore, the head module 212 in this example is equipped with a common recovery channel 280, and individual recovery channels 282 are connected to the nozzle channels 254 of each ejector 222. The individual recovery channels 282 are connected to the common recovery channel 280.

[0178] In Figure 12, reference numeral 266 denotes a cover plate. The cover plate 266 is a member that maintains the movable space 268 of the piezoelectric element 252 and seals the area around the piezoelectric element 252. Above the cover plate 266, a supply-side ink chamber and a recovery-side ink chamber (not shown) are formed. The supply-side ink chamber is connected to the supply-side common flow path 226 via a connecting passage (not shown). The recovery-side ink chamber is connected to the recovery-side common flow path 280 via a connecting passage (not shown). Ink supplied from the supply-side common flow path 226 to the pressure chamber 250 via the individual supply path 224 is discharged from the nozzle 220 through the nozzle flow path 254. Ink that is not used for discharge is recovered from the nozzle flow path 254 to the recovery-side common flow path 280 via the individual recovery path 282.

[0179] When there is a pressure difference between the supply-side common flow path 226 and the recovery-side common flow path 280, and ink is not 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 adopting such an ink circulation structure, the viscosity of the ink in the pressure chamber 250 is prevented, and the ejection stability can be improved. When refilling after ejecting ink from the ejector 222, ink is supplied to the pressure chamber 250 from the supply-side common flow path 226 via the individual supply path 224, and ink is also supplied to the pressure chamber 250 from the recovery-side common flow path 280 via the individual recovery path 282. In other words, the recovery-side common flow path 280 not only plays a role in recovering ink from the ejector 222, but can also play a role in supplying ink to the ejector 222 during refilling.

[0181] Regarding the hardware configuration of various processing 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, processing liquid application control unit 314, processing liquid drying control unit 316, drawing control unit 318, ink drying control unit 320, paper discharge control unit 324, and communication unit 304, as described in Figure 3, consists of the following types of processors.

[0182] Various types of processors include CPUs (Central Processing Units), which are general-purpose processors that execute programs and function as various processing units; Programmable Logic Devices (PLDs), such as FPGAs (Field Programmable Gate Arrays), which are processors whose circuit configuration can be changed after manufacturing; and Dedicated Electrical Circuits, such as ASICs (Application Specific Integrated Circuits), which are processors with circuit configurations specifically designed to perform particular processing.

[0183] A single processing unit may be composed of one of these various processors, or it may be composed of two or more processors of the same or different type. For example, a single processing unit may be composed of multiple FPGAs, or a combination of a CPU and an FPGA. Alternatively, multiple processing units may be composed of a single processor. Examples of composing multiple processing units with a single processor include, firstly, a configuration where one or more CPUs and software are combined to form a single processor, and this processor functions as multiple processing units, as is typical of computers such as client and server systems. Secondly, a configuration where a processor is used that realizes the functions of the entire system, including multiple processing units, on a single IC (Integrated Circuit) chip, as is typical of System-on-a-Chip (SoC) systems. Thus, various processing units are configured, in terms of hardware structure, using one or more of the above-mentioned various processors.

[0184] Furthermore, the hardware structure of these various processors is, more specifically, an electrical circuit composed of circuit elements such as semiconductor devices.

[0185] Regarding programs that enable a computer to function as a control device: It is possible to record a program that implements the control functions of the inkjet printing apparatus 1 described in the above embodiment onto a computer-readable medium, such as an optical disc or magnetic disc, which is a tangible, non-temporary information storage medium, and provide the program through this information storage medium. Alternatively, instead of providing the program by storing it on such a tangible, non-temporary information storage medium, it is also possible to provide the 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-liquid agglutination system and the one-liquid agglutination 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. That is, the inkjet printing apparatus 1 is capable of high-quality printing in standard mode (two-liquid agglutination system), while switching to the one-liquid agglutination system enables high-speed transport in high-speed mode, thereby enabling high-productivity printing.

[0187] [2] In high-speed mode, the drying intensity is automatically changed to a table corresponding to high-speed mode, and the drying intensity is increased compared to standard mode, thus eliminating insufficient drying due to high-speed transport.

[0188] 《Example 1》 In the above-described embodiment, an inkjet printing apparatus 1 using a page-wide full-line type head was explained. However, the scope of application of the present invention is not limited to this, and the present invention can also be applied to inkjet printing apparatuses that perform image formation by multiple head scans while moving a short recording head, such as a serial type head.

[0189] 《Modified Example 2》 In the embodiments described above, an example using water-based ink was explained, but UV-curable ink may be used instead of water-based ink. When UV-curable ink is used, the inkjet printing apparatus 1 is equipped with a UV irradiation device in place of, or in addition to, the heating and drying section 90.

[0190] Regarding the inkjet head ejection method: The ejector of an inkjet head comprises a nozzle for ejecting ink, a pressure chamber leading to the nozzle, and an ejection energy generating element that provides ejection energy to the liquid in the pressure chamber. Regarding the ejection method for ejecting droplets from the ejector nozzle, the means for generating ejection energy is not limited to piezoelectric elements; various ejection energy generating elements such as heating elements and electrostatic actuators can be applied. For example, a method can be employed that utilizes the pressure of film boiling caused by heating the liquid with a heating element to eject droplets. Depending on the ejection method of the inkjet head, appropriate ejection energy generating elements are provided in the flow path structure.

[0191] Regarding recording media: In the embodiments described above, an example was given in which a sheet of paper P is used as the recording medium. However, the medium used for recording images is not limited to a sheet of paper, but may also be a continuous medium such as continuous paper. Furthermore, the sheet of paper is not limited to pre-cut sheets of paper of a predetermined size, but may also be obtained by cutting a continuous medium to a predetermined size as needed.

[0192] The term "recording medium" is a general term encompassing various things known by different names such as paper, recording paper, printing paper, printing media, printing medium, printable medium, image-forming medium, image-receiving medium, and ejected medium. The material and shape of the medium are not particularly limited, and various sheet materials can be used, regardless of material or shape, including sticker paper, resin sheets, films, cloth, nonwoven fabrics, and others.

[0193] Regarding the transport mechanism for recording media: The transport mechanism for transporting the recording medium is not limited to the drum transport method exemplified in Figure 1; various other configurations can be employed, such as belt transport, nip transport, chain transport, and pallet transport, and these methods can be combined as appropriate.

[0194] Regarding terminology: The term "printing apparatus" is synonymous with terms such as printing press, printer, printing device, image recording device, image forming device, image output device, or drawing device.

[0195] The term "image" is interpreted broadly and includes color images, black and white images, single-color images, gradient images, and images with uniform density (solid colors). "Image" is used as a comprehensive term that includes not only photographic images, but also patterns, characters, symbols, line drawings, mosaic patterns, color-coded patterns, and various other patterns, or appropriate combinations thereof.

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

[0197] Regarding combinations of embodiments and variations: The configurations described in the above embodiments and the modifications described can be used in appropriate combinations, and some of the items can also be replaced.

[0198] The embodiments of the present invention described above can be modified, added to, or deleted as appropriate without departing from the spirit of the invention. The present invention is not limited to the embodiments described above, and many modifications are possible within the technical concept of the present invention by those with ordinary skill in the equivalent related field. [Explanation of Symbols]

[0199] 1. Inkjet printing device 10 Paper feed section 11. Conveying mechanism 12 Paper feeder 12A paper feed stand 14 Feeder Board 16 Paper feed drum 20 Processing liquid application unit 22 Processing liquid application drum 23 Grippa 24 Processing liquid coating device 25 Applicator roller 30 Processing liquid drying section 32 Processing liquid drying drum 33 Grippa 34 Hot air blower 40 Drawing section 42 drawing drums 43 Grippa 44 Head Unit 46 inkjet heads 46C Inkjet Head 46M inkjet head 46Y Inkjet Head 46K inkjet head 48 Image reading device 50 Ink drying area 60 Accumulation Unit 62. Integration device 62A Integration Tray 70 Chain Gripper 71A First sprocket 71B 2nd sprocket 72 chain 74 Grippa 80 Paper Guide 82. First Paper Guide 84. Second Paper Guide 90 Heat drying treatment process 102 Suction Transfer Device 110 belt 110A Conveyor 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 component 220 nozzles 222 Ejector 224 Individual supply route 224A Nozzle Row 226 Common supply channel 250 pressure chamber 252 Piezoelectric element 254 Nozzle Flow Channels 256 Diaphragm 258 individual electrodes 260 Piezoelectric 266 Cover Plate 268 Movable space 280 Common flow path on the recovery side 282 Individual collection routes 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 supply control unit 316 Processing liquid drying control unit 318 Drawing Control Unit 320 Ink drying control unit 324 Paper output control unit 332 Image memory 334 Parameter Storage Unit 336 Program Storage Unit 400 host computers P paper S11-S34 Processing steps in an inkjet printing apparatus

Claims

1. A transport mechanism for transporting recording media, A coating apparatus for applying a pretreatment solution to the recording medium, An inkjet head that ejects ink, The system includes a processor that controls the transport speed of the recording medium and the coating operation of the coating device when forming an image on the recording medium by ejecting the ink from the inkjet head, When the processor transports the recording medium at a first transport speed to form the image on the recording medium, it causes the coating device to apply the pretreatment liquid. An image forming apparatus that, when transporting the recording medium at a second transport speed faster than the first transport speed to form an image on the recording medium, controls the coating apparatus to refrain from applying the pretreatment liquid, The aforementioned processor, When the recording medium is transported at the first transport speed to form the image, the maximum amount of ink droplets ejected per dot from the nozzle of the inkjet head is set to the first droplet amount. When the recording medium is transported at the second transport speed to form the image, the maximum ink droplet amount is set to a second droplet amount which is smaller than the first droplet amount. To cause an image of lower quality than the image formed on the recording medium transported at the first transport speed to be formed on the recording medium transported at the second transport speed. Image forming apparatus.

2. The processor receives an 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. When the first mode is specified, the pretreatment solution is applied; when the second mode is specified, the pretreatment solution is not applied. The image forming apparatus according to claim 1.

3. The device further comprises a drying apparatus for drying the ink that has been attached to the recording medium, The processor controls the drying apparatus to a first drying intensity when the recording medium is transported at a first transport speed, and controls the drying apparatus to a second drying intensity that is higher than the first drying intensity when the recording medium is transported at a second transport speed. The image forming apparatus according to claim 1 or 2.

4. A transport mechanism for transporting recording media, A coating apparatus for applying a pretreatment solution to the recording medium, An inkjet head that ejects ink, A method for manufacturing a printed material using an image forming apparatus comprising: a processor that controls the transport speed of the recording medium and the coating operation of the coating device when forming an image on the recording medium by ejecting the ink from the inkjet head, The processor receives an input of an instruction to change the transport speed, When a first transport speed is specified as the transport speed, the transport mechanism transports the recording medium at the first transport speed, the coating device applies the pretreatment liquid to the recording medium, and the ink ejected from the inkjet head adheres to the recording medium to which the pretreatment liquid has been applied, thereby forming an image on the recording medium. When a second transport speed higher than the first transport speed is specified as the transport speed, the transport mechanism transports the recording medium at the second transport speed, the coating device does not apply the pretreatment liquid to the recording medium, and the ink ejected from the inkjet head adheres to the recording medium, which is not coated with the pretreatment liquid, thereby forming an image on the recording medium. The aforementioned processor, When the recording medium is transported at the first transport speed to form the image, the maximum amount of ink droplets ejected per dot from the nozzle of the inkjet head is set to the first droplet amount. When the recording medium is transported at the second transport speed to form the image, the maximum ink droplet amount is set to a second droplet amount which is smaller than the first droplet amount. A method for manufacturing a printed material, comprising causing the recording medium being transported at the second transport speed to form an image of lower quality than the image formed on the recording medium being transported at the first transport speed.

Images