Discharge control device, inkjet printing system, printing condition determination method and program

Abstract

To provide a discharge control device, an inkjet printing system, a method and a program, which enable adjustment to achieve discharge stability of an inkjet head in continuous printing.SOLUTION: A printing condition determination method includes: acquiring a first printing condition including one or more printing parameters (S10); performing continuous printing to which two or more printing numbers are applied using an inkjet head to which the first printing condition is applied (S12); performing measurement of the discharge state of the inkjet head in the continuous printing twice or more, analyzing the discharge state of the inkjet head using the two or more measurement results acquired in each of two or more of the measurement, and deriving a printing condition determination index indicating the continuous change of the discharge state of the inkjet head in the continuous printing (S14); and evaluating the first printing condition using the printing condition determination index (S18).SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a discharge control device, an inkjet printing system, a printing condition determination method, and a program. [Background technology]

[0002] Printing devices using inkjet heads require optimization of printing conditions, such as the drive waveform applied to drive the inkjet head. Printing devices using inkjet heads also require adjustment of printing conditions, such as the correction value that determines the amplitude of the drive voltage. The amplitude of the drive voltage refers to the potential difference in the pulse voltage.

[0003] It is known that the optimum drive waveform for an inkjet head varies depending on the individual inkjet head due to differences in the resistance of the internal flow path, etc. It is also known that the amplitude of the drive voltage suitable for stable ejection varies depending on the ink used.

[0004] For example, the amplitude of the drive waveform and drive voltage is designed in advance, and the flight state and the amount of ejection deflection are evaluated and determined in advance. Also, rather than determining the optimal drive voltage from the perspective of ejection stability, the amplitude of the drive voltage may be adjusted using a specified chart to keep the density of the printed image constant. The amount of ejection deflection refers to an ejection position error.

[0005] Patent Document 1 describes an inkjet printing device that corrects printing conditions based on the print results. The device described in this document reads a printed image using a scanner, analyzes the read image, and corrects printing conditions or performs maintenance on the inkjet head based on the analysis results. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-60596 Summary of the Invention [Problem to be solved by the invention]

[0007] However, if only one type of optimized drive waveform is maintained, it becomes difficult to adjust the drive waveform according to the ejection state of each inkjet head, and the ejection stability of the inkjet head may deteriorate. When a large amount of printing is performed continuously using an inkjet head with deteriorated ejection stability, defects such as streaks may occur in the printed image.

[0008] Furthermore, when the driving voltage is adjusted using a specified chart to keep the density of the printed image constant, it may not be optimally adjusted from the perspective of ejection stability, and there is a risk that the inkjet head will be used in a state where ejection stability has decreased.

[0009] In an inkjet head that selectively uses a plurality of droplet sizes, such as large droplets, medium droplets, and small droplets, the size ratio between the droplet sizes may differ depending on the individual inkjet head.

[0010] In this case, even if the amplitude of the driving voltage is optimized using the density of the printed image and the volume of the ink droplets as parameters, there may be cases where the amplitude of the driving voltage is not optimized from the viewpoint of ejection stability.

[0011] Patent Document 1 describes that ejection abnormalities such as non-ejection and deflected ejection are inspected and printing conditions are corrected or inkjet head maintenance is performed, but it does not mention the viewpoint of continuous changes in the ejection state, such as changes over time in the ejection state during continuous printing. With the device described in the document, it is difficult to guarantee ejection stability, which is important in actual continuous printing.

[0012] The present invention has been made in consideration of the above circumstances, and aims to provide an ejection control device, an inkjet printing system, a printing condition determination method, and a program that enable adjustments that can achieve ejection stability of an inkjet head during continuous printing. [Means for solving the problem]

[0013] In order to achieve the above object, the following aspects of the invention are provided.

[0014] The discharge control device according to the present disclosure includes one or more processors and one or more memories storing a program to be executed by the one or more processors, wherein the one or more processors execute instructions of the program to obtain first printing conditions including one or more printing parameters, perform continuous printing applying two or more print runs using an inkjet head to which the first printing conditions are applied, measure the discharge state of the inkjet head two or more times during the continuous printing, analyze the discharge state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, derive a printing condition determination index that represents continuous changes in the discharge state of the inkjet head during the continuous printing, and evaluate the first printing condition using the printing condition determination index.

[0015] According to the ejection control device of the present disclosure, in continuous printing where a first printing condition is applied, the first printing condition is evaluated using a printing condition determination index derived based on two or more measurement results of the ejection state of the inkjet head, the printing condition determination index representing continuous changes in the ejection state of the inkjet head. This makes it possible to derive a printing condition determination index that can achieve ejection stability of the inkjet head during continuous printing.

[0016] The inkjet head has a plurality of nozzles for ejecting ink, and may have a structure in which a plurality of head modules are arranged.

[0017] In the discharge control device according to another aspect, the one or more processors may perform statistical processing on two or more measurement results to derive the printing condition determination index.

[0018] According to this aspect, it is possible to grasp continuous changes in the ejection state of the inkjet head during continuous printing.

[0019] In the discharge control device according to another aspect, the one or more processors may derive, as the printing condition determination index, a standard deviation of discharge position error for each nozzle provided in the inkjet head during continuous printing.

[0020] According to this aspect, it is possible to derive a printing condition determination index based on the ejection position error for each nozzle.

[0021] In another embodiment of the discharge control device, one or more processors may perform multiple consecutive printings, calculate an arithmetic mean of the printing condition determination index derived for each consecutive printing, and evaluate the first printing condition using the arithmetic mean of the printing condition determination index.

[0022] According to this aspect, the statistical processing may involve calculating the arithmetic mean of the printing condition determination indexes derived for each of the multiple consecutive printings.

[0023] In the discharge control device according to another aspect, the one or more processors may calculate the printing condition determination index using measurement results of the discharge state of the inkjet head obtained during multiple consecutive printings.

[0024] According to this aspect, it is possible to grasp continuous changes in the ejection state of the inkjet head during multiple consecutive printings.

[0025] In another aspect of the discharge control device, one or more processors may select the worst printing condition determination index from the printing condition determination indexes calculated for each of multiple consecutive printings, and evaluate the first printing condition using the selected printing condition determination index.

[0026] According to this aspect, it is possible to grasp continuous changes in the ejection state of the inkjet head during multiple consecutive printings.

[0027] In the discharge control device according to another aspect, the one or more processors may calculate a score representing an evaluation of the printing condition determination index.

[0028] According to this aspect, the printing condition determination index can be evaluated based on the score.

[0029] In another aspect of the discharge control device, the one or more processors may acquire first printing conditions as printing parameters, the first printing conditions including at least one of a driving waveform, an amplitude of a driving voltage, and a pressure applied to an air-liquid interface in a nozzle portion provided in the inkjet head.

[0030] According to this aspect, the first printing conditions can be evaluated based on at least one of the drive waveform, the amplitude of the drive voltage, and the pressure applied to the gas-liquid interface in the nozzle portion provided in the inkjet head.

[0031] In the discharge control device according to another aspect, the one or more processors may derive a printing condition determination index that indicates a change in discharge deflection of the inkjet head during continuous printing.

[0032] According to this aspect, the first printing conditions can be evaluated based on changes in the ejection deflection of the inkjet head during continuous printing.

[0033] In another aspect of the ejection control device, one or more processors may read a test pattern image printed by applying a first printing condition, generate read data of the test pattern image, and use the read data to measure the ejection status of the inkjet head.

[0034] According to this aspect, the ejection state of the inkjet head can be measured based on the read data of the test pattern image printed using the first printing conditions.

[0035] In another aspect of the discharge control device, the first printing conditions when printing a test pattern image may include at least one of a drive waveform that promotes the occurrence of discharge abnormalities and an amplitude of a drive voltage that promotes the occurrence of discharge abnormalities.

[0036] According to this aspect, it is possible to promote the occurrence of ejection abnormalities in an inkjet head with an unstable ejection state.

[0037] In the discharge control device according to another aspect, the one or more processors may derive a printing condition determination index that represents a quantitative value of the ink mist adhering to the discharge surface of the inkjet head.

[0038] According to this aspect, the first printing conditions can be evaluated based on the quantitative value of the ink mist adhering to the ejection surface of the inkjet head.

[0039] In a discharge control device according to another aspect, the one or more processors may determine second printing conditions to replace the first printing conditions based on the evaluation results of the first printing conditions.

[0040] According to this aspect, it is possible to set printing conditions that can achieve a continuously stable ejection state for the inkjet head during continuous printing.

[0041] In another aspect of the discharge control device, one or more memories may store a plurality of drive waveform elements that constitute the drive waveform, and one or more processors may generate a drive waveform that combines two or more drive waveform elements from the plurality of stored drive waveform elements as a printing parameter included in the second printing condition.

[0042] According to this aspect, it is possible to derive printing conditions that can achieve a continuously stable ejection state by adjusting the combination of drive waveform elements.

[0043] In another aspect of the ejection control device, one or more processors may apply second printing conditions to perform continuous printing, measure the ejection state of the inkjet head during the continuous printing two or more times, analyze the ejection state of the inkjet head using two or more measurement results obtained from each of the two or more measurements, derive a printing condition determination index that represents continuous changes in the ejection state of the inkjet head during the continuous printing and that corresponds to the second printing condition, and evaluate the second printing condition using the printing condition determination index that corresponds to the second printing condition.

[0044] According to this aspect, the printing conditions can be changed successively to derive the best printing conditions.

[0045] In another aspect of the discharge control device, one or more processors may compare a printing condition determination index derived by applying a first printing condition with a printing condition determination index derived by applying a second printing condition, and determine the printing condition corresponding to the good printing condition determination index as the printing condition to be applied to continuous printing.

[0046] According to this aspect, it is possible to derive good printing conditions while dynamically changing the printing conditions.

[0047] The inkjet printing system according to the present disclosure is an inkjet printing system including an inkjet head that ejects ink, and an ejection control device that controls the ink ejection from the inkjet head, wherein the ejection control device includes one or more processors and one or more memories that store a program to be executed by the one or more processors, and the one or more processors execute instructions of the program to obtain first printing conditions including one or more printing parameters, apply the first printing conditions to the inkjet head, perform continuous printing using the inkjet head, with two or more print runs applied, measure the ejection state of the inkjet head two or more times during the continuous printing, analyze the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, derive a printing condition determination index that represents continuous changes in the ejection state of the inkjet head during the continuous printing, and evaluate the first printing conditions using the printing condition determination index.

[0048] The inkjet printing system according to the present disclosure can achieve the same effects as the ejection control device according to the present disclosure. The components of the ejection control device according to other aspects can be applied to the components of the inkjet printing system according to other aspects.

[0049] The printing condition determination method according to the present disclosure is a printing condition determination method in which a computer acquires first printing conditions including one or more printing parameters for printing to which an inkjet head is applied, applies the first printing conditions to the inkjet head, performs continuous printing using the inkjet head to print two or more times, measures the ejection state of the inkjet head in the continuous printing, analyzes the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, derives a printing condition determination index that represents continuous changes in the ejection state of the inkjet head in the continuous printing, and evaluates the first printing condition using the printing condition determination index.

[0050] According to the printing condition determination method of the present disclosure, it is possible to obtain the same effects as the discharge control device of the present disclosure. The constituent elements of the discharge control device of other aspects can be applied to the constituent elements of the printing condition determination method of other aspects.

[0051] The program according to the present disclosure is a program that enables a computer to perform the following functions: acquire first printing conditions including one or more printing parameters for printing to which an inkjet head is applied; apply the first printing conditions to the inkjet head and perform continuous printing using the inkjet head, with two or more print runs applied; measure the ejection state of the inkjet head two or more times in the continuous printing; analyze the ejection state of the inkjet head using two or more measurement results obtained from each of the two or more measurements, and derive a printing condition determination index that represents continuous changes in the ejection state of the inkjet head in the continuous printing; and evaluate the first printing conditions using the printing condition determination index.

[0052] According to the program of the present disclosure, it is possible to obtain the same effects as the discharge control device of the present disclosure. The constituent elements of the discharge control device of other aspects can be applied to the constituent elements of the program of other aspects. [Effects of the Invention]

[0053] According to the present invention, in continuous printing using first printing conditions, the first printing conditions are evaluated using a printing condition determination index derived based on two or more measurement results of the ejection state of the inkjet head, the printing condition determination index representing continuous changes in the ejection state of the inkjet head. This makes it possible to derive a printing condition determination index that can achieve ejection stability of the inkjet head during continuous printing. [Brief explanation of the drawings]

[0054] [Figure 1] FIG. 1 is a diagram showing the overall configuration of an inkjet printing system according to the first embodiment. [Figure 2]FIG. 2 is a perspective view showing an example of the configuration of an inkjet printer. [Figure 3] FIG. 3 is a perspective view of the head module, including a partial cross-sectional view. [Figure 4] FIG. 4 is a cross-sectional view showing the internal structure of the head module. [Figure 5] FIG. 5 is a functional block diagram showing the electrical configuration of the inkjet printing system shown in FIG. [Figure 6] FIG. 6 is a functional block diagram of the jetting condition setting unit shown in FIG. [Figure 7] FIG. 7 is a block diagram showing an example of the hardware configuration of the electrical configuration shown in FIGS. [Figure 8] FIG. 8 is a flowchart showing the procedure of the jetting condition determination method according to the first embodiment. [Figure 9] FIG. 9 is a schematic diagram of a printed image showing a specific example of a test pattern image. [Figure 10] FIG. 10 is a schematic diagram of a test pattern image showing a modified example of the test pattern image. [Figure 11] FIG. 11 is a graph showing the amount of deflection of the ejection for each nozzle. [Figure 12] FIG. 12 is a graph showing the amount of deflection of ink ejected onto a printing medium from a nozzle in which the ejection state is stable. [Figure 13] FIG. 13 is a graph showing the amount of deflection of ink ejection relative to the number of prints made from a nozzle in an unstable ejection state. [Figure 14] FIG. 14 is a schematic diagram of a multi-pulse driving waveform. [Figure 15] Figure 15 shows an image of the nozzle surface taken with a high-speed camera. [Figure 16] FIG. 16 is a trimmed image obtained by trimming the nozzle formation region from the photographed image of the nozzle surface shown in FIG. [Figure 17] FIG. 17 is a binarized image obtained by performing binarization processing on the trimmed image shown in FIG. [Figure 18]FIG. 18 is a graph showing the relationship between the time interval between waveform elements and the velocity of the ink droplet. DETAILED DESCRIPTION OF THE INVENTION

[0055] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification, the same components are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0056] [Inkjet printing system according to the first embodiment] [Overall structure] 1 is a diagram showing the overall configuration of an inkjet printing system according to a first embodiment. The arrows in the figure schematically indicate the substrate transport direction, which is the direction in which a film substrate 1 is transported in each device included in the inkjet printing system 10.

[0057] The actual substrate transport direction for each device is the direction in which the film substrate 1 travels, that is, the direction along the traveling direction of the film substrate 1. That is, the arrows shown in Figure 1 indicate that in the inkjet printing system 10, the film substrate 1 travels through the paper feeder 12, pre-coater 14, jetting device 16, drying device 18, and inspection device 20 in that order.

[0058] The inkjet printing system 10 is a printing system that employs a single-pass method and uses aqueous color inks to print color images on a film substrate 1. The film substrate 1 is a transparent, non-permeable medium used for flexible packaging.

[0059] Examples of the film substrate 1 include ONY (oriented nylon), OPP (oriented polypropylene), and PET (polyethylene terephthalate). The inkjet printing system 10 produces reverse-printed printed matter that can be viewed from the substrate support surface 1B opposite the printing surface 1A of the film substrate 1. The inkjet printing system 10 can also produce front-printed printed matter that can be viewed from the printing surface 1A.

[0060] "Non-permeable" refers to being non-permeable to the aqueous primer and aqueous ink described below. "Flexible packaging" refers to packaging made of a material that deforms depending on the shape of the packaged item. "Transparent" refers to a visible light transmittance of 30% or more and 100% or less, preferably 70% or more and 100% or less.

[0061] The inkjet printing system 10 includes a paper feeder 12, a precoater 14, a jetting device 16, a drying device 18, an inspection device 20, a collection device 22, and a transport device 24. Each of these devices will be described in detail below.

[0062] [Paper feeding device] A roll-to-roll transport system is applied to the inkjet printing system 10. The paper feeder 12 includes a delivery roll around which the film substrate 1 is wound before an image is printed. The delivery roll includes a rotatably supported reel.

[0063] The paper feeder 12 may be equipped with a corona treatment device that applies a modification treatment to the printing surface 1A of the film substrate 1. The modified printing surface 1A of the film substrate 1 has a surface free energy suitable for the aqueous mixture of the aqueous primer and the aqueous ink, ensuring suitable wettability for the aqueous mixture. The film substrate 1 is transported to the precoater 14.

[0064] [Precoat device] The precoat device 14 is disposed downstream of the paper feed device 12 in the substrate transport direction and upstream of the jetting device 16. The precoat device 14 applies a precoat liquid to the printing surface 1A of the film substrate 1.

[0065] The precoat device 14 may include a precoat drying device. The precoat drying device dries the precoat liquid applied to the film substrate 1. The precoat liquid may be a liquid containing a component that insolubilizes or thickens the water-based ink, such as an aqueous primer liquid. The film substrate 1 to which the precoat liquid has been applied and dried is transported to the jetting device 16.

[0066] [Jetting device] The jetting device 16 includes an inkjet head 30K, an inkjet head 30C, an inkjet head 30M, an inkjet head 30Y, and an inkjet head 30W.

[0067] Inkjet head 30K, inkjet head 30C, inkjet head 30M, inkjet head 30Y, and inkjet head 30W eject black ink, cyan ink, magenta ink, yellow ink, and white ink, respectively. Hereinafter, when there is no need to distinguish between inkjet heads 30K, etc., they will be referred to as inkjet head 30.

[0068] The inkjet head 30 is a line type head in which multiple nozzles are arranged across the entire length of the film substrate 1 in the substrate width direction. Note that a serial type head may also be used as the inkjet head 30. The substrate width direction is a direction perpendicular to the substrate transport direction and parallel to the printing surface of the film substrate 1.

[0069] The aqueous ink ejected from the inkjet head 30 is an ink in which a coloring material such as a pigment is dissolved or dispersed in a water-soluble solvent. The pigment used in the aqueous ink is an organic pigment. The viscosity of the aqueous ink is 0.5 centipoise or more and 5.0 centipoise or less.

[0070] The inkjet head 30 ejects color inks onto the printing surface 1A of the film substrate 1, which is transported using the transport device 24, to print a color image on the film substrate 1. The white ink forms a white background image on the film substrate 1. Note that multiple inkjet heads 30W that eject water-based white ink may be provided.

[0071] The inkjet heads 30 are arranged and oriented so that the nozzle surfaces that eject ink face the substrate conveyance surface of the substrate conveyance path, which is the conveyance path for the film substrate 1. The inkjet heads 30 are arranged at equal intervals along the substrate conveyance direction.

[0072] 1 shows an embodiment in which four water-based inks are used, but the ink colors are not limited to black, cyan, magenta, and yellow. For example, an embodiment in which light-colored inks such as light magenta and light cyan are used, or an embodiment in which special color inks such as green, orange, violet, clear, and metallic are used, are also applicable. Furthermore, the arrangement order of the inkjet heads for each color is not limited to the example shown in FIG. 1.

[0073] The jetting device 16 includes a scanner 32. The scanner 32 includes an imaging device that captures an image of the test pattern printed on the printing surface of the film substrate 1 and converts the captured image into an electrical signal.

[0074] Examples of imaging devices include CCD image sensors and color CMOS image sensors. CCD is an abbreviation for Charge Coupled Device, and CMOS is an abbreviation for Complementary Metal Oxide Semiconductor.

[0075] The image data output from the scanner 32 is sent to the scan data analysis unit. The scan data analysis unit identifies abnormal nozzles such as non-discharge nozzles based on the image data of the test pattern. The film substrate 1 is transported to the drying device 18. Note that capturing the test pattern image described in the embodiment is an example of reading the test pattern image. [Drying equipment] The drying device 18 is disposed downstream of the jetting device 16 in the substrate transport direction and upstream of the inspection device 20 in the substrate transport direction. The drying device 18 includes a drying module that dries the aqueous ink adhered to the printing surface 1A of the film substrate 1. The film substrate 1 from which the aqueous ink has dried is transported to the inspection device 20.

[0076] [Inspection equipment] The inspection device 20 is disposed downstream of the drying device 18 in the substrate transport direction and upstream of the recovery device 22 in the substrate transport direction. The inspection device 20 inspects the image printed on the film substrate 1 for defects.

[0077] The inspection device 20 includes an imaging device that captures an image printed on the film substrate 1 and an illumination device that irradiates the film substrate 1 with illumination light. The image data of the printed image is used to determine whether or not there are any defects in the printed image. The film substrate 1 after the inspection of the printed image is transported to a recovery device 22.

[0078] [Recovery device] The recovery device 22 recovers the film substrate 1 on which the image has been printed. Specifically, the film substrate 1 on which the image has been printed is wound onto a take-up roll. The recovery device 22 may also cut the film substrate 1 into individual printed images to produce printed matter in the form of sheets. The test pattern image may be cut off from the film substrate 1 when the film substrate 1 is cut into individual printed images.

[0079] [Transportation device] A roll-to-roll system is applied to the conveying device 24. The conveying device 24 conveys the film substrate 1 along a substrate conveyance path in the substrate conveyance direction from the paper feeding device 12 to the recovery device 22, in the order of the paper feeding device 12, precoating device 14, jetting device 16, drying device 18, inspection device 20, and recovery device 22. The paper feeding device 12 and the recovery device 22 may be included in the conveying device 24.

[0080] The conveying device 24 includes a plurality of pass rollers 34. One or more pass rollers 34 are arranged in each of the paper feeding device 12, the precoating device 14, the jetting device 16, the drying device 18, the inspection device 20, and the recovery device 22.

[0081] The conveying device 24 includes one or more tension pickups 36 arranged in each of the paper feeder 12, pre-coating device 14, jetting device 16, drying device 18, inspection device 20, and recovery device 22. The tension pickups 36 detect the tension applied to the film substrate 1. A detection signal from the tension pickups 36 is sent to the conveying control unit. The conveying control unit is illustrated in FIG. 5 using the reference numeral 102. In FIG. 1, the tension pickup 36 provided in the jetting device 16 is illustrated, and the tension pickups 36 provided in the paper feeder 12, etc. are not illustrated.

[0082] In the present embodiment, the conveying device 24 is exemplified by a roll-to-roll method for a continuous body, but the conveying device 24 may also be configured to take out and convey sheets one by one from a stocker.

[0083] The conveying device 24 may also be equipped with a conveying mechanism such as a conveying belt and a conveying drum instead of the plurality of pass rollers 34. Furthermore, the conveying device 24 may combine an embodiment in which the plurality of pass rollers 34 is equipped with a conveying belt or the like.

[0084] The film substrate 1 is not limited to a transparent substrate. An opaque substrate having a visible light transmittance of less than 30% may be used as the film substrate 1. Instead of the film substrate 1, substrates such as paper, cloth, and film-like metal substrates may be used.

[0085] [Example of inkjet head configuration] 2 is a perspective view showing an example of the configuration of an inkjet head. The inkjet head 30 shown in the figure has a structure in which multiple head modules 40 are connected along the longitudinal direction. The multiple head modules 40 are integrally supported by a support frame 42.

[0086] Each head module 40 is connected to two flexible substrates 44. On the flexible substrates 44, electrical wiring for transmitting a drive voltage supplied to the ejection elements provided in the head module 40 is formed.

[0087] The head module 40 has a plurality of nozzle openings formed in a nozzle surface 46. A liquid-repellent film that is ink-repellent is formed on the nozzle surface 46. The nozzle openings may be arranged in any manner, such as a matrix arrangement. The nozzle openings are shown in FIG. 4 and labeled with the reference numeral 80.

[0088] 3 is a perspective view of the head module, including a partial cross-sectional view. The head module 40 has an ink supply unit made up of an ink supply chamber 50, an ink circulation chamber 52, etc., on the top surface side in FIG. 3, which is the side opposite to the nozzle surface 46 of the nozzle plate 48.

[0089] The ink supply chamber 50 is connected to an ink tank via a supply-side individual flow path 54. The ink circulation chamber 52 is connected to an ink tank via a recovery-side individual flow path 56. The ink tank is not shown in the drawing.

[0090] 4 is a cross-sectional view showing the internal structure of the head module 40. The head module 40 includes ink supply channels 60, individual supply channels 62, pressure chambers 64, nozzle communication channels 66, individual circulation channels 68, a common circulation channel 70, piezoelectric elements 72, and a vibration plate 74.

[0091] The ink supply channels 60, individual supply channels 62, pressure chambers 64, nozzle connecting channels 66, individual circulation channels 68, and common circulation channel 70 are formed in a channel structure 76. The nozzle section 78 includes a nozzle opening 80 and a nozzle connecting channel 66. The nozzle connecting channel 66 is a channel that constitutes the ejection element, and corresponds to the channel that communicates with the nozzle opening 80.

[0092] The individual supply channels 62 are channels that connect the pressure chambers 64 and the ink supply channels 60. The nozzle communication channels 66 are channels that connect the pressure chambers 64 and the nozzle openings 80. The individual circulation channels 68 are channels that connect the nozzle communication channels 66 and the common circulation channel .

[0093] A vibration plate 74 is disposed on the flow path structure 76. A piezoelectric element 72 is disposed on the vibration plate 74 via an adhesive layer 82. The piezoelectric element 72 has a layered structure of a lower electrode 84, a piezoelectric layer 86, and an upper electrode 88. The lower electrode 84 is sometimes called a common electrode, and the upper electrode 88 is sometimes called an individual electrode.

[0094] The upper electrode 88 is an individual electrode patterned to correspond to the shape of each pressure chamber 64, and each pressure chamber 64 is provided with a piezoelectric element 72. The piezoelectric element 72 corresponds to an energy generating element that constitutes an ejection element.

[0095] The ink supply path 60 communicates with the ink supply chamber 50 shown in Figure 3. Ink is supplied from the ink supply path 60 to the pressure chamber 64 via the individual supply path 62. A drive voltage is applied to the upper electrode 88 of the piezoelectric element 72 to be operated in accordance with the original data of the print image, causing the piezoelectric element 72 and the diaphragm 74 to deform and changing the volume of the pressure chamber 64. The head module 40 ejects ink droplets from the nozzle openings 80 via the nozzle communication path 66 in accordance with the change in pressure that accompanies the change in volume of the pressure chamber 64.

[0096] The pressure chambers 64 corresponding to each nozzle opening 80 have a roughly square planar shape, with an outlet to the nozzle opening 80 located at one of the diagonal corners and an individual supply path 62 serving as an ink inlet located at the other. The shape of the pressure chamber is not limited to a square. The planar shape of the pressure chamber can be a variety of shapes, such as a diamond, a rectangle, or other quadrangle, a pentagon, a hexagon, or other polygon, a circle, or an ellipse.

[0097] A circulation outlet 90 is formed in the nozzle communication passage 66. The nozzle communication passage 66 is connected to the individual circulation flow path 68 via the circulation outlet 90. Of the ink held in the nozzle portion 78, ink that is not used for ejection is collected into the common circulation flow path 70 via the individual circulation flow path 68.

[0098] 3. The ink is collected into the common circulation flow path 70 via the individual circulation flow paths 68. This prevents the ink held in the nozzle portions 78 from thickening during non-ejection periods.

[0099] 4 illustrates a piezoelectric element 72 having a structure in which the piezoelectric elements 72 are individually separated in correspondence with the plurality of nozzle portions 78. Of course, a structure in which a piezoelectric layer 86 is formed integrally with the plurality of nozzle portions 78, an individual electrode is formed in correspondence with each of the plurality of nozzle portions 78, and an active region is formed for each nozzle portion 78 may also be applied.

[0100] The nozzle openings 80 are arranged in a two-dimensional manner on the nozzle surface 46. An example of a two-dimensional arrangement is a matrix arrangement. The arrangement of the nozzle openings 80 is not limited to a matrix, and a single row arrangement or a two-row zigzag arrangement, etc., can also be applied. The arrangement of the nozzle openings 80 on the nozzle surface 46 is not shown in the drawings. A water-repellent film may be formed on the nozzle surface 46.

[0101] 4 illustrates the head module 40 having the piezoelectric element 72 as the energy generating element, but a heater may also be used as the energy generating element. The inkjet head 30 having a heater ejects ink droplets from the nozzle openings 80 by utilizing the film boiling phenomenon of ink.

[0102] [Electrical configuration of inkjet printing system] Figure 5 is a functional block diagram showing the electrical configuration of the inkjet printing system shown in Figure 1. The inkjet printing system 10 includes a system control unit 100. The system control unit 100 comprehensively controls the overall operation of the inkjet printing system 10. The system control unit 100 sends command signals to various control units.

[0103] The inkjet printing system 10 includes a memory 130. The memory 130 stores various types of information that are applied to the inkjet printing system 10. The memory 130 also stores various programs that are applied to the inkjet printing system 10.

[0104] The system control unit 100 functions as a memory controller that controls the storage of data in the memory 130 and the reading of data and programs from the memory 130. The memory 130 may be configured to include multiple devices, or may be configured such that one device is divided into multiple areas.

[0105] The inkjet printing system 10 includes a transport control unit 102 , a pre-coat control unit 104 , a jetting control unit 106 , a drying control unit 108 , an inspection control unit 110 , and a scan control unit 112 .

[0106] The transport control unit 102 sets transport conditions based on command signals sent from the system control unit 100, and controls the operation of the transport device 24 based on the set transport conditions. For example, the transport control unit 102 applies the transport conditions to the transport device 24 and controls the operation of a motor connected to a drive roller or the like provided in the transport device 24.

[0107] The precoat control unit 104 sets the processing conditions for the precoat process based on a command signal sent from the system control unit 100, and controls the operation of the precoat device 14 based on the set processing conditions.

[0108] The jetting control unit 106 controls the operation of the jetting device 16 based on a command signal sent from the system control unit 100. In other words, the jetting control unit 106 controls the ink ejection from the inkjet head 30.

[0109] The jetting control unit 106 includes a drive voltage generation unit and a drive voltage output unit. The drive voltage generation unit reads a drive waveform that has been generated and stored in advance, and generates a drive voltage to be supplied to the inkjet head 30. A memory 130 may be used to store the drive waveform.

[0110] The drive voltage output unit outputs a drive voltage to be supplied to the jetting device 16. The drive voltage output unit includes an AD conversion unit that converts a digital drive waveform into an analog format and a power amplification unit. The drive voltage output unit applies a specified ejection cycle and selectively outputs a drive voltage for each nozzle.

[0111] The drying control unit 108 sets the processing conditions for the drying process applied to the drying device 18 based on a command signal sent from the system control unit 100, and controls the operation of the drying device 18 based on the set processing conditions.

[0112] The inspection control unit 110 sets inspection conditions to be applied to the inspection device 20 based on a command signal sent from the system control unit 100, and controls the operation of the inspection device 20 based on the set inspection conditions.

[0113] The scan control unit 112 sets scan conditions such as scan resolution and scan cycle for the scanner 32 and controls the operation of the scanner 32. The scan control unit 112 acquires scan data transmitted from the scanner 32 and stores the scan data. The memory 130 may be used to store the scan data.

[0114] The inkjet printing system 10 includes an image data processing unit 120. The image data processing unit 120 acquires original data for the print image, such as in PDF format, from an external device such as a host computer via an input interface, and performs color separation processing, color conversion processing, correction processing for each processing, and halftone processing on the original data for the print image to generate halftone data based on the image data. The jetting control unit 106 outputs a drive voltage for each nozzle to the jetting device 16 based on the halftone data.

[0115] The inkjet printing system 10 includes a scan data analysis unit 122 and a discharge detection unit 124. The scan data analysis unit 122 analyzes the scan data acquired via the scan control unit 112, and derives the discharge position for each nozzle provided in the inkjet head 30.

[0116] Based on the analysis results of the scan data analysis unit 122, the discharge detection unit 124 detects the presence or absence of discharge for each inkjet head 30 and for each nozzle, the presence or absence of deflected discharge, and the presence or absence of abnormality in the ink discharge amount.

[0117] The inkjet printing system 10 includes a jetting condition setting unit 126. The jetting condition setting unit 126 sets jetting conditions to be applied to the jetting device 16 based on command signals sent from the system control unit 100.

[0118] The jetting conditions may include the amplitude, drive waveform, and back pressure of the drive voltage supplied to the inkjet head 30. The back pressure is the pressure applied to the meniscus in the nozzle portion of the inkjet head 30. The gas-liquid interface in the nozzle portion is called the meniscus in the nozzle portion.

[0119] The jetting condition setting unit 126 stores the jetting conditions. The jetting conditions can be stored in the memory 130. The jetting conditions and the setting of the jetting conditions will be described in detail later.

[0120] The jetting conditions described in the embodiments are examples of printing conditions, and the amplitude, drive waveform, and back pressure of the drive voltage described in the embodiments are examples of printing parameters.

[0121] The inkjet printing system 10 includes a sensor 132. The system control unit 100 acquires a sensor signal transmitted from the sensor 132 and transmits a command signal based on the sensor signal to various control units. The sensor 132 shown in Fig. 5 includes a position detection sensor and a temperature sensor provided in each unit of the inkjet printing system shown in Fig. 1.

[0122] Fig. 6 is a functional block diagram of the jetting condition setting unit shown in Fig. 5. The jetting condition setting unit 126 includes a scan data acquisition unit 140 and an index calculation unit 142. The scan data acquisition unit 140 acquires the analysis results of the scan data from the scan data analysis unit 122. Specifically, the scan data acquisition unit 140 acquires the ejection deflection amount, which represents the ejection position error for each inkjet head 30 and each nozzle. Note that the scan data described in the embodiment is an example of read data of a test pattern image.

[0123] The index calculation unit 142 calculates a jetting condition determination index that indicates the ejection stability of each inkjet head 30 and each nozzle during continuous printing, using the amount of ejection deflection for each inkjet head 30 and each nozzle.

[0124] The jetting condition judgment index is the standard deviation σ of the amount of jetting deflection, which indicates the variation in the amount of jetting deflection for each nozzle. t The standard deviation of the discharge deflection amount σ t can be calculated by applying the following procedure:

[0125] Each time a test pattern image is printed, the ejection position of each nozzle is measured, the error in the ejection position of each nozzle is measured, and the amount of ejection deflection of each nozzle is derived. During continuous printing, the amount of ejection deflection of each nozzle is measured multiple times, and the multiple amounts of ejection deflection of each nozzle are statistically processed, and the standard deviation σ of the amount of ejection deflection is used as a jetting condition judgment index. t is calculated.

[0126] Standard deviation σ of discharge deflection t is associated with the jetting conditions and stored. The standard deviation σ of the ejection deflection amount associated with the jetting conditions t The memory 130 shown in FIG. 5 is used for storing the above.

[0127] The jetting condition setting unit 126 includes a jetting condition acquisition unit 144, a jetting condition determination unit 146, and a jetting condition output unit 148. The jetting condition acquisition unit 144 acquires the jetting conditions when calculating the jetting condition determination index. The jetting condition determination unit 146 calculates the standard deviation σ of the discharge deflection amount calculated using the index calculation unit 142. t is evaluated for each jetting condition, and based on the evaluation results, the optimum jetting conditions are determined for each inkjet head 30. The jetting conditions include the amplitude of the drive waveform and the drive voltage.

[0128] The jetting condition setting unit 126 outputs optimal jetting conditions for each inkjet head 30 via the jetting condition output unit 148. The jetting condition setting unit 126 also stores the determined jetting conditions in the jetting condition storage unit 130A. When determining the jetting conditions, the jetting condition setting unit 126 reads out the jetting conditions corresponding to the scan data from the jetting condition storage unit 130A. The jetting condition storage unit 130A can be included in the memory 130 shown in FIG. 5.

[0129] Figure 7 is a block diagram showing an example of the hardware configuration of the electrical configuration shown in Figures 5 and 6. The control device 200 provided in the inkjet printing system 10 includes a processor 202, a non-transitory tangible computer-readable medium 204, a communication interface 206, and an input / output interface 208.

[0130] A computer is applied to the control device 200. The computer may be in the form of a server, a personal computer, a workstation, a tablet terminal, or the like. The computer may also be a virtual computer.

[0131] The processor 202 includes a central processing unit (CPU). The processor 202 may include a graphics processing unit (GPU). The processor 202 is connected to a computer-readable medium 204, a communication interface 206, and an input / output interface 208 via a bus 210. An input device 214 and a display device 216 are connected to the bus 210 via the input / output interface 208.

[0132] The computer-readable medium 204 includes a memory serving as a primary storage device and a storage serving as an auxiliary storage device. The computer-readable medium 204 may be a semiconductor memory, a hard disk drive, a solid-state drive, or the like. The computer-readable medium 204 may be any combination of multiple devices.

[0133] A hard disk drive may be referred to as an HDD, which is an abbreviation of the English term Hard Disk Drive, and a solid state drive may be referred to as an SSD, which is an abbreviation of the English term Solid State Drive.

[0134] The control device 200 is connected to a network via a communication interface 206, and is communicably connected to an external device. The network may be a local area network (LAN), etc. The network is not shown in the figure.

[0135] The computer-readable medium 204 stores a transport control program 220 and a precoat control program 222. The transport control program 220 corresponds to the transport control applied to the transport device 24 shown in Fig. 2. The precoat control program 222 corresponds to the precoat control applied to the precoat device 14.

[0136] The computer-readable medium 204 stores an image data processing program 224 and a jetting control program 226. The image data processing program 224 corresponds to image processing applied to the image data processing unit 120. The jetting control program 226 corresponds to jetting control applied to the jetting control unit 106.

[0137] The computer-readable medium 204 stores a drying control program 228 and an inspection control program 230. The drying control program 228 corresponds to the drying control applied to the drying control unit 108. The inspection control program 230 corresponds to the inspection applied to the inspection control unit 110.

[0138] The computer-readable medium 204 stores a scan control program 232, a scan data analysis program 234, and a discharge detection program 236. The scan control program 232 corresponds to the control of the scanner 32 applied to the scan control unit 112. The scan data analysis program 234 corresponds to the analysis processing of scan data applied to the scan data analysis unit 122. The discharge detection program 236 corresponds to the discharge inspection applied to the discharge detection unit 124.

[0139] The computer-readable medium 204 stores a jetting condition setting program 238. The jetting condition setting program 238 corresponds to a process for setting jetting conditions applied to the jetting condition setting unit 126.

[0140] The jetting condition setting program 238 may include an index calculation program and a jetting condition determination program, both of which are not shown in the drawings.

[0141] The various programs stored in the computer-readable medium 204 include one or more instructions. Various data, various parameters, etc. are stored in the computer-readable medium 204. The memory 130 shown in FIG. 2 is included in the computer-readable medium 204 shown in FIG. 3.

[0142] In the inkjet printing system 10, the processor 202 executes various programs stored in the computer-readable medium 204 to realize various functions of the inkjet printing system 10. Note that the term "program" is synonymous with the term "software."

[0143] The control device 200 performs data communication with an external device via a communication interface 206. The communication interface 206 may be compliant with various standards such as USB (Universal Serial Bus). The communication form of the communication interface 206 may be either wired communication or wireless communication.

[0144] The control device 200 is connected to an input device 214 and a display device 216 via an input / output interface 208. The input device 214 is implemented by input devices such as a keyboard and a mouse. The display device 216 displays various information applied to the control device 200.

[0145] The display device 216 may be a liquid crystal display, an organic EL display, a projector, or any combination of multiple devices. The EL in organic EL display is an abbreviation for Electro-Luminescence.

[0146] Examples of the hardware structure of the processor 202 include a CPU, a GPU, a PLD (Programmable Logic Device), and an ASIC (Application Specific Integrated Circuit). A CPU is a general-purpose processor that executes programs and functions as various functional units. A GPU is a processor specialized for image processing.

[0147] A PLD is a processor whose electrical circuit configuration can be changed after the device is manufactured. An example of a PLD is an FPGA (Field Programmable Gate Array). An ASIC is a processor with dedicated electrical circuitry designed specifically to perform a specific task.

[0148] A processing unit may be configured with one of these various processors, or may be configured with two or more processors of the same or different types. Examples of combinations of various processors include a combination of one or more FPGAs and one or more CPUs, and a combination of one or more FPGAs and one or more GPUs. Another example of a combination of various processors is a combination of one or more CPUs and one or more GPUs.

[0149] A single processor may be used to configure multiple functional units. An example of using a single processor to configure multiple functional units is a configuration in which a single processor is configured by applying a combination of one or more CPUs and software, such as an SoC (System On a Chip), which is typified by a computer such as a client or server, and this processor operates as multiple functional units.

[0150] Another example of using one processor to configure multiple functional units is to use a processor that uses one IC chip to realize the functions of an entire system including multiple functional units. Note that IC is an abbreviation for Integrated Circuit.

[0151] In this way, the various functional units are configured as hardware structures using one or more of the various processors described above.More specifically, the hardware structures of the various processors described above are electric circuits (circuitry) that combine circuit elements such as semiconductor elements.

[0152] The computer-readable medium 204 may include semiconductor devices such as read-only memory (ROM) and random-access memory (RAM). The computer-readable medium 204 may include a magnetic storage medium such as a hard disk. The computer-readable medium 204 may comprise multiple types of storage media.

[0153] [Procedure of Jetting Condition Determination Method According to First Embodiment] 8 is a flowchart showing the steps of the jetting condition determination method according to the first embodiment. Each step of the jetting condition determination method is executed by various processing units constituting the inkjet printing system 10 to which a computer is applied.

[0154] The jetting condition determination method shown in FIG. 8 is a method for determining the standard deviation σ of the jetting deviation, which represents the variation of the jetting deviation in continuous printing, for a plurality of jetting conditions defined in advance. tCalculate the standard deviation of the discharge deflection σ t The drive waveform and drive voltage amplitude that minimizes are determined as the optimum jetting conditions.

[0155] In the jetting condition setting step S10, jetting conditions to be applied to continuous printing are set using the jetting condition setting unit 126 shown in Fig. 5. For example, it is assumed that initial conditions preset in the inkjet printing system 10 are set. After the jetting condition setting step S10, the process proceeds to the continuous printing step S12.

[0156] In the jetting condition setting step S10 described in the embodiment, the jetting conditions set as the evaluation targets are an example of first printing conditions.

[0157] In the continuous printing step S12, continuous printing of a plurality of sheets is performed by the jetting control unit 106, and scan data of the test pattern image to be printed on each sheet is obtained using the scanner 32. The test pattern image is illustrated in FIG. 9 with the reference numeral 304.

[0158] A sheet of continuous media refers to an area of ​​continuous media that corresponds to a sheet of sheet-fed media. One print image may be printed on one sheet, or multiple print images may be printed on one sheet.

[0159] Continuous printing can refer to a single print job that prints multiple sheets. The print job may use only the same original image data, or multiple different original image data. Continuous printing can also refer to multiple print jobs that are performed consecutively.

[0160] Note that the continuous printing of a plurality of sheets described in the embodiment is an example of continuous printing in which the number of prints is two or more.

[0161] During the continuous printing step S12, an index calculation step S14 is executed. In the index calculation step S14, the index calculation unit 142 shown in Fig. 6 calculates the standard deviation σ of the amount of ejection deflection, which represents the variation in the amount of ejection deflection during continuous printing, from the amount of ejection deflection for each nozzle derived using the scan data analysis unit 122 sequentially acquired during continuous printing. t is calculated for each inkjet head 30 and each nozzle.

[0162] Standard deviation σ of the amount of deflection of the ejection for each inkjet head 30 and each nozzle t is associated with the jetting conditions as a jetting condition determination index and stored. Note that the measurement of the amount of ejection deflection based on scan data acquired successively during continuous printing described in the embodiment is an example of measuring the ejection state of the inkjet head two or more times. The standard deviation σ of the amount of ejection deflection, which represents the variation in the amount of ejection deflection during continuous printing described in the embodiment, t is an example of a printing condition determination index that indicates a continuous change in the ejection state of the inkjet head.

[0163] Once the jetting condition determination index is calculated in the index calculation step S14, a jetting condition change determination step S16 is executed. In the jetting condition change determination step S16, the jetting condition setting unit 126 determines whether or not there are other jetting conditions to be evaluated.

[0164] In the jetting condition change determination step S16, if the jetting condition setting unit 126 determines that there are other jetting conditions to be evaluated, the determination is Yes. If the determination is Yes, the process proceeds to the jetting condition setting step S10. Until the determination is No in the jetting condition change determination step S16, the processes from the jetting condition setting step S10 to the jetting condition change determination step S16 are repeatedly executed, and jetting condition determination indexes are calculated for all jetting conditions to be evaluated.

[0165] On the other hand, in the jetting condition change determination step S16, if the jetting condition setting unit 126 determines that the jetting condition determination indexes have been calculated for all jetting conditions to be evaluated, the determination is No. If the determination is No, the process proceeds to the jetting condition determination step S18.

[0166] Figure 8 illustrates an example in which the index calculation process S14 and the jetting condition change determination process S16 are performed in the continuous printing process S12, but the index calculation process S14 and the jetting condition change determination process S16 may also be performed during continuous printing, such as at the timing of switching between continuous printing.

[0167] In the jetting condition determination step S18, the jetting condition determination unit 146 determines the standard deviation σ of the ejection deflection amount, which is the jetting condition determination index. t The jetting conditions that minimize the value of are determined for each inkjet head 30.

[0168] That is, in the jetting condition determination step S18, the jetting condition with the best jetting condition determination index calculated for each of the plurality of jetting conditions is determined for each inkjet head 30 as the jetting condition for continuous printing.

[0169] After the jetting condition determination step S18, the process proceeds to a continuous printing end determination step S20. The jetting condition with the best jetting condition determination index, which is determined as the jetting condition for continuous printing, is an example of the second printing condition.

[0170] In the continuous printing end determination step S20, the jetting control unit 106 determines whether or not to continue continuous printing. If the jetting control unit 106 determines to continue continuous printing in the continuous printing end determination step S20, the determination is Yes. If the determination is Yes, the process proceeds to the jetting condition setting step S10, and each of the steps from the jetting condition setting step S10 to the continuous printing end determination step S20 is repeatedly executed until the determination is No in the continuous printing end determination step S20.

[0171] On the other hand, in the continuous printing end determination step S20, if the jetting control unit 106 determines that continuous printing should be ended, the determination is No. If the determination is No, the procedure of the jetting condition determination method ends.

[0172] The jetting conditions in continuous printing may be changed during continuous printing, or may be changed during a rest period of the inkjet head 30, such as when switching continuous printing or pausing continuous printing.

[0173] In the present embodiment, an example has been given in which the jetting conditions are determined for each inkjet head 30 based on the jetting condition determination index, but in an inkjet head 30 that includes multiple head modules 40, the jetting conditions may be determined for each head module 40. Furthermore, the jetting conditions may be determined for each nozzle and for each nozzle block that includes multiple nozzles.

[0174] [Example of test pattern image] 9 is a schematic diagram of a print medium showing a specific example of a test pattern image. The print medium 300 shown in the figure is a single sheet of medium, which represents any one of the multiple print images printed on the film substrate 1 shown in FIG.

[0175] A test pattern image 304, which may be called a ladder pattern or a 1-on-N-off pattern, is printed in a leading edge region 302 of the print medium 300. The leading edge region 302 of the print medium 300 is an area where a print image 306 is not printed, and is an area closer to a leading edge 308 of the print medium 300 than the print image 306.

[0176] The center of Fig. 9 shows an enlarged view of the test pattern image 304 printed on the print medium 300 shown in the lower part of Fig. 9. The upper part of Fig. 9 shows an enlarged view of a portion of the test pattern image 304 shown in the center of Fig. 9.

[0177] The test pattern image 304 is printed using all nozzles. Of all nozzles, nozzles within a range where the ejection state is normal print pattern elements 310 at specified positions. On the other hand, non-ejecting nozzles that are unable to eject ink cannot print pattern elements 310, and pattern elements 310 are not printed at positions corresponding to the non-ejecting nozzles.

[0178] Within a circle 312 in which some of the pattern elements 310 that make up the test pattern image 304 are enlarged, dashed lines are used to schematically illustrate pattern elements 310A that correspond to non-ejecting nozzles and are not printed.

[0179] The printed pattern elements 310 may contain errors from the specified position depending on the ejection state of each nozzle. Nozzles with relatively large errors from the specified position, i.e., nozzles with large variations, may suddenly exhibit large ejection deflections and may be identified as nozzles with low ejection stability. In this way, the amount of ejection deflection for each nozzle is calculated, the variation in the amount of ejection deflection for each nozzle is calculated, and the ejection stability of each nozzle can be evaluated based on the variation in the amount of ejection deflection for each nozzle.

[0180] The test pattern image 304 may be printed on all printing media 300 that are to be printed continuously, or may be printed on one printing medium 300 for every two or ten printing media 300.

[0181] 10 is a schematic diagram showing a modified example of a test pattern image, in which a print medium 300 has a first test pattern image 304A printed in a leading edge region 302, a second test pattern image 304B printed in a middle margin region 303, and a third test pattern image 304C printed in a trailing edge region 305.

[0182] The intermediate margin area 303 is a margin area between the print images 306. The rear end area 305 of the print medium 300 is an area where the print images 306 are not printed, and is an area closer to the rear end 309 of the print medium 300 than the print images 306.

[0183] If the number of times the ejection state of the inkjet head 30 is evaluated increases relatively, the number of printed sheets and the time required to perform the process will increase, which can increase the processing load. Therefore, in optimizing the jetting conditions, multiple test pattern images 304 are printed on one sheet of printing medium 300, making it possible to calculate the jetting condition determination index multiple times using one sheet of printing medium 300. This can suppress the increase in processing load.

[0184] 10 shows an example in which multiple print images 306 are printed on one sheet of print medium 300. For example, in continuous printing, an adjustment mode may be executed in which a test pattern image 304 is printed on one sheet of print medium 300 after every 100 sheets are printed. In the adjustment mode, multiple test pattern images 304 may be printed on the entire surface of one sheet of print medium 300.

[0185] [Detailed explanation of jetting condition determination index calculation] Figure 11 is a graph showing the amount of deflection of the discharge for each nozzle. The horizontal axis of the graph in this figure is the nozzle number, and the vertical axis is the standard deviation, which shows the variation in the amount of deflection of the discharge. The nozzle numbers are assigned in order, starting with the nozzle at one end as number 1, in a projected nozzle row in which multiple nozzles arranged in a matrix are projected in the longitudinal direction of the inkjet head 30 and aligned in the same direction. Figure 11 shows an example where the number of nozzles is 900.

[0186] The vertical axis of the graph shown in Figure 11 represents the normalized standard deviation of the amount of ejection deflection for each nozzle. The standard deviation of the amount of ejection deflection for each nozzle is plotted as the value obtained each time scan data of the test pattern image 304 is acquired during continuous printing. Nozzles with densely packed plots are nozzles with relatively high ejection stability, while nozzles with discrete plots are nozzles with relatively low ejection stability. In this way, the ejection stability of each nozzle can be grasped.

[0187] Fig. 12 is a graph showing the amount of deflection of ejection relative to the number of printed sheets for nozzles with stable ejection conditions, and Fig. 13 is a graph showing the amount of deflection of ejection relative to the number of printed sheets for nozzles with unstable ejection conditions.

[0188] Figure 12 shows the amount of deflection of an arbitrary nozzle with a stable ejection state out of the multiple nozzles shown in Figure 11. Figure 13 shows the amount of deflection of an arbitrary nozzle with an unstable ejection state out of the multiple nozzles shown in Figure 11. The horizontal axis of the graphs shown in Figures 12 and 13 represents the number of prints, and the vertical axis represents the amount of deflection of the ejection. The amount of deflection of the ejection is a normalized value of the absolute error from a specified ejection position, and is shown as a ratio to a reference value where the specified reference value is 1.

[0189] The nozzles showing the amount of deflected ejection in Figure 12 always have stable ejection conditions during continuous printing, whereas the nozzles showing the amount of deflected ejection in Figure 13 experience relatively large deflected ejection around the 150th printed sheet.

[0190] When the standard deviation is calculated for the deflected discharge amounts shown in FIGS. 12 and 13, the nozzles showing the deflected discharge amounts in FIG. 12 have relatively small standard deviations, while the nozzles showing the deflected discharge amounts in FIG. 13 have relatively large standard deviations.

[0191] That is, a nozzle with a relatively large standard deviation of the amount of deflected ejection can be judged to have a relatively large variation in the amount of deflected ejection and an unstable ejection state, whereas a nozzle with a relatively small standard deviation of the amount of deflected ejection can be judged to have a relatively small variation in the amount of deflected ejection and a stable ejection state.

[0192] In this embodiment, the standard deviation of the amount of deflection of the ejection of each nozzle in one continuous printing run is used as an example of statistical processing, but variance may be used instead of the standard deviation. Also, the results of statistical processing in multiple continuous printing runs may be further statistically processed to calculate an index.

[0193] For example, the amount of deflection of the ink jetting for each of a plurality of consecutive print runs may be stored, and the standard deviation may be calculated for all of the deflection of the ink jetting for the plurality of consecutive print runs. Alternatively, the standard deviation for each of the plurality of consecutive print runs may be stored, and the arithmetic mean of the standard deviations for the plurality of consecutive print runs may be calculated. Furthermore, the standard deviation for each of the plurality of consecutive print runs may be stored, and the maximum value of the standard deviation may be used as the index.

[0194] [Example of multi-pulse drive waveform] Figure 14 is a schematic diagram of a multi-pulse drive waveform. This figure shows the drive waveform in a graphical format. The horizontal axis of the graph shown in this figure is time, with the unit of time being microseconds. The vertical axis is voltage, with the unit being volts.

[0195] 14 illustrates a multi-pulse driving waveform 400 including a first waveform element 402, a second waveform element 404, a third waveform element 406, a fourth waveform element 408, and a fifth waveform element 410. A driving voltage is applied to one or more of the waveform elements from the first waveform element 402 to the fifth waveform element 410.

[0196] For example, when three different sizes of droplets are used, small, medium, and large, in order of decreasing droplet volume, the first wave element 402 may be selected for the small droplets, and the first wave element 402 and the second wave element 404 may be selected for the medium droplets. Also, the first wave element 402 through the fifth wave element 410 may be selected for the large droplets. Droplet size refers to the volume of the droplets.

[0197] When optimizing jetting conditions, variations in waveform elements and combinations of waveform elements may be performed. For example, when ejecting a droplet, the second waveform element 404 may be selected instead of the first waveform element 402.

[0198] Furthermore, when ejecting a medium droplet, instead of the combination of the first wave element 402 and the second wave element 404, the combination of the third wave element 406 and the fourth wave element 408 may be selected.

[0199] Furthermore, when ejecting a large droplet, the first wave element 402 may be deleted from the combination of the first wave element 402 to the fifth wave element 410, and a combination of the second wave element 404 to the fifth wave element 410 may be selected. Note that the first wave element 402 and the like described in the embodiment are examples of drive waveform elements.

[0200] [Effects of the first embodiment] According to the printing system and jetting condition determination method according to the first embodiment, the following advantageous effects can be obtained.

[0201] [1] During continuous printing, the ejection state of each nozzle of the inkjet head 30 is measured, and the measurement results are statistically processed to calculate a jetting condition determination index that represents the stability of the ejection state during continuous printing, and the jetting condition determination index is evaluated. A jetting condition determination index is calculated for each of a plurality of predefined jetting conditions, and each jetting condition determination index is evaluated. Jetting conditions that result in good evaluation results for the jetting condition determination index are determined as jetting conditions to be applied to continuous printing. This ensures good ejection stability of the inkjet head 30 during continuous printing.

[0202] [2] The amount of deflection of the ejection of each nozzle of the inkjet head 30 during continuous printing is statistically processed to obtain the standard deviation σ of the amount of deflection of the ejection, which represents the variation in the amount of deflection of the ejection. t is calculated as a jetting condition determination index. This makes it possible to evaluate the jetting conditions based on the variation in the amount of ejection deflection for each nozzle.

[0203] [3] The jetting conditions include at least one of the drive waveform, drive voltage, and back pressure, which can determine the drive voltage and other factors that will provide good ejection stability from the inkjet head 30 during continuous printing.

[0204] [4] For a multi-pulse driving waveform composed of multiple waveform elements, the jetting condition determination index is calculated for multiple jetting conditions with different combinations of waveform elements, and the jetting condition determination index is evaluated. As a result, the multi-pulse driving waveform having the optimal combination of waveform elements can be defined as the jetting condition.

[0205] [Jeting condition determination method according to the second embodiment] The jetting condition determination method according to the second embodiment aims to reduce the number of sequences when sequentially evaluating a plurality of predefined jetting conditions, thereby improving the efficiency of evaluation of the jetting conditions.

[0206] The jetting condition determination method according to the second embodiment is applied to the inkjet printing system 10 according to the first embodiment as a hardware configuration. Here, a description of the hardware will be omitted.

[0207] 8 are executed from the jetting condition setting step S10 to the index calculation step S14. In the jetting condition change determination step S16, the jetting conditions to be evaluated next are dynamically generated from the jetting conditions calculated in the index calculation step S14.

[0208] For example, a drive waveform A1 is set as an initial drive waveform, and a jetting condition determination index B1 is calculated. If the jetting condition determination index B1 shows a good result, a jetting condition determination index B2 is calculated for a drive waveform A2 similar to the drive waveform A1.

[0209] The evaluation of the jetting condition determination index B1 is compared with the evaluation of the jetting condition determination index B2, and if the evaluation of the jetting condition determination index B1 shows a better result than the evaluation of the jetting condition determination index B2, the drive waveform A1 is determined as the jetting condition.

[0210] If the evaluation of the jetting condition determination index B2 shows a favorable result compared to the evaluation of the jetting condition determination index B1, the jetting condition determination index B3 is calculated for a drive waveform A3 similar to the drive waveform A2, and the evaluation of the jetting condition determination index B2 is compared with the evaluation of the jetting condition determination index B3. In this way, the jetting conditions including the best drive waveform are derived.

[0211] On the other hand, if the evaluation of the jetting condition determination index B1 corresponding to the drive waveform A1 is significantly poor, a jetting condition determination index B4 is calculated and evaluated for a drive waveform A4 that is dissimilar to the drive waveform A1. If the evaluation of the jetting condition determination index B4 indicates a good result, a jetting condition determination index B5 is calculated for a drive waveform A5 that is similar to the drive waveform A4, and the evaluation of the jetting condition determination index B4 and the evaluation of the jetting condition determination index B5 are compared. In this way, the optimal drive waveform can be derived.

[0212] The same procedure as for the drive waveform can be adopted for the amplitude of the drive voltage. For example, the jetting condition determination index is calculated and evaluated by setting the initial drive voltage amplitude to 100 percent. The jetting condition determination index is calculated and evaluated by setting the drive voltage amplitude to 105 percent. By comparing the two, if the evaluation of the jetting condition determination index when the drive voltage amplitude is 105 percent shows a good result, the jetting condition determination index when the drive voltage amplitude is 110 percent is calculated and evaluated. In this way, it is possible to dynamically derive the jetting condition that provides the best evaluation result for the pre-defined jetting conditions.

[0213] [Effects of the second embodiment] According to the jetting condition determination method of the second embodiment, it is possible to reduce the number of sequences compared to when a plurality of predetermined jetting conditions are comprehensively evaluated.

[0214] [Jeting condition determination method according to the third embodiment] The jetting condition determination method according to the third embodiment devise a test pattern image that is applied to measure the amount of ejection deflection for each nozzle, thereby emphasizing the jetting condition judgment indicators for each jetting condition and highlighting unsatisfactory jetting conditions.

[0215] The jetting condition determination method according to the third embodiment is applied to the inkjet printing system 10 according to the first embodiment as a hardware configuration. Here, a description of the hardware will be omitted.

[0216] 9 is printed immediately before and after the print image 306 in which high-density printing is performed. In another example, the length of the pattern element 310 of the test pattern image 304 is relatively increased. For example, if the original length of the pattern element 310 is 0.65 mm, the actual length of the pattern element 310 is set to 1.0 mm.

[0217] This increases the probability that a nozzle with an unstable ejection state will have an ejection abnormality, making it easier to determine whether or not a nozzle with an unstable ejection state has an ejection abnormality. Note that the drive waveform that increases the probability that a nozzle with an unstable ejection state will have an ejection abnormality, as described in the embodiment, is an example of a drive waveform that promotes the occurrence of an ejection abnormality. Furthermore, the amplitude of the drive voltage that increases the probability that a nozzle with an unstable ejection state will have an ejection abnormality is an example of a drive voltage amplitude that promotes the occurrence of an ejection abnormality.

[0218] [Jeting condition determination method according to the fourth embodiment] In the jetting condition determination method according to the fourth embodiment, the amount of ink mist adhering to the nozzle surface during continuous printing is used as a jetting condition determination index. When continuous printing is performed, ink mist adheres to the nozzle surface 46 of the inkjet head 30. The ink mist adhering to the nozzle surface 46 can cause a deterioration in the ejection status of the inkjet head 30.

[0219] 15 is a photographed image of the nozzle surface taken using a high-speed camera. This figure shows an enlarged view of a portion of the nozzle surface 46 shown in FIG. 2. The photographed image 440 shown in FIG. 15 shows a large amount of ink mist I in the nozzle formation region 46A of the nozzle surface 46. m It shows that the substance is attached.

[0220] Fig. 16 is a trimmed image obtained by trimming the nozzle formation region from the photographed image of the nozzle face shown in Fig. 15. Trimmed image 442 shown in Fig. 16 is generated by performing region extraction processing on photographed image 440 shown in Fig. 15. Known image processing techniques can be applied to the region extraction processing.

[0221] Fig. 17 is a binarized image obtained by performing binarization processing on the trimmed image shown in Fig. 16. The number of pixels included in a white area 446 in a binarized image 444 shown in Fig. 17 is counted, and the ink mist I is calculated from the count value of the number of pixels in the white area 446. m In this way, the area on which the ink mist I adheres to the nozzle surface 46 can be calculated from the captured image 440 of the nozzle surface 46. m The quantified ink mist I m can be used as a jetting condition determination index.

[0222] Ink mist I adhering to nozzle surface 46 m As a jetting condition determination index related to the above, the ink mist I adhering to the nozzle surface 46 is m Volume of ink mist during continuous printing m Ink mist I showing the increase or decrease of m The gradient of the volume of

[0223] In addition, the ink mist I adhering to the nozzle surface 46 between multiple print jobs m The total volume, maximum volume, standard deviation, etc. may be used as the jetting condition determination index. Furthermore, any combination of these may be used as the jetting condition determination index.

[0224] Furthermore, the standard deviation σ of the amount of deflection of the discharge, which is used as the jetting condition determination index in the first embodiment, etc. t and the ink mist I adhering to the nozzle surface 46 mFor example, when combining a plurality of jetting condition determination indexes, a weight may be defined for each of the plurality of jetting condition determination indexes, and the jetting condition determination indexes may be multiplied by the weight and added together.

[0225] The nozzle surface 46 may be photographed using a high-speed camera disposed on the movement path of the inkjet head 30. Instead of moving the inkjet head 30, the high-speed camera may be moved relative to the inkjet head 30, which is fixedly disposed.

[0226] The nozzle surface 46 described in the embodiment is an example of an ejection surface. m The area where the ink mist adheres to the nozzle surface 46 is m Volume and Ink Mist I m The gradient of the volume is an example of a quantitative value of the ink mist.

[0227] [Jeting condition determination method according to the fifth embodiment] In the jetting condition determination method according to the fifth embodiment, a drive waveform is dynamically generated by selectively combining multiple waveform elements. The jetting condition determination method according to the fifth embodiment uses the inkjet printing system 10 according to the first embodiment as its hardware configuration. A description of the hardware will be omitted here.

[0228] [Clarifying the issues] In an inkjet printing system that uses an inkjet head, the drive waveform of the drive voltage that drives the inkjet head is optimized to achieve stable ink ejection from the inkjet head and produce high-quality printed images.

[0229] However, it is known that the optimal drive waveform varies depending on the type of ink, the usage conditions of the inkjet head, and individual differences between inkjet heads. Examples of usage conditions of the inkjet head include the installation environment of the inkjet head and the back pressure setting of the inkjet head. Examples of individual differences between inkjet heads include differences in flow path resistance of the ink flow path and mechanical errors in the mechanical components of the inkjet head.

[0230] As mentioned above, when only one type of optimized driving waveform is maintained, it is difficult to adjust it according to the ejection state of each inkjet head, which requires know-how every time the jetting conditions and ink, etc. are changed, and it takes a relatively long time to evaluate the jetting conditions, etc.

[0231] For example, in the case of a multi-pulse drive waveform that combines multiple waveform elements as shown in Figure 14, the types of combinations of waveform elements are limited by the number of waveform elements. Also, the adjustable parameters are limited by the pulse width, amplitude, slope, etc. Furthermore, the pulse width and slope are limited by the resonance period of the inkjet head that realizes efficient ink ejection.

[0232] Furthermore, when evaluating jetting conditions by repeated trial and error, there is a risk that optimal jetting conditions may not be found and that the jetting conditions may be optimized locally.

[0233] [Specific Embodiments] A plurality of single-pulse drive waveforms that will become the waveform elements of the multi-pulse drive waveform are prepared in advance. For example, the first waveform element 402 to the fifth waveform element 410 shown in Fig. 14 are each generated as a single-pulse drive waveform.

[0234] The number of pulses to be combined is specified, and all multi-pulse drive waveforms having the specified number of waveform elements are generated. A jetting condition determination index is calculated and evaluated for each multi-pulse drive waveform, and the jetting condition corresponding to the jetting condition determination index with the best evaluation result is determined.

[0235] For example, multiple multi-pulse drive waveforms are prepared, an evaluation score is calculated for each multi-pulse drive waveform, the multi-pulse drive waveform is adjusted according to the evaluation score, and the next candidate multi-pulse drive waveform is generated. This procedure is repeated until the multi-pulse drive waveform is optimized.

[0236] The optimization of the multipulse drive waveform may be performed by applying a trained learning model. For example, a trained learning model may be generated by learning a combination of a plurality of multipulse drive waveforms and the evaluation scores for each multipulse drive waveform as training data, and the multipulse drive waveform may be optimized using the trained learning model.

[0237] The learning model may be a deep learning model such as a convolutional neural network (CNN).

[0238] When combining multiple waveform elements, it is necessary to specify the time interval between each waveform element. The time interval between waveform elements can be the time interval between waveform elements at which the ink droplet velocity reaches its maximum value. This allows for efficient ink ejection.

[0239] FIG. 18 is a graph showing the relationship between the time interval between waveform elements and the velocity of the ink droplet. The horizontal axis of the graph shown in FIG. 18 is the time interval between waveform elements, in units of microseconds. This is indicated as KEEP TIME [μs] in the figure. The vertical axis of the graph shown in FIG. 18 is the velocity of the ink droplet, in units of meters per second. This is indicated as ejection velocity V [m / s] in the figure.

[0240] The velocity of the ink droplet is measured for the time intervals between multiple waveform elements, and the graph shown in Figure 18 is created. The velocity of the ink droplet can be determined by photographing the ink droplet using a high-speed camera and deriving the velocity from the photographed data of the ink droplet. It is also possible to photograph the ink droplet multiple times for the same time interval between waveform elements, and use a representative value such as the arithmetic average or maximum value as the velocity of the ink droplet.

[0241] The graph shown in FIG. 18 is created from the ink droplet velocity for each time interval between multiple waveform elements. The time interval t between waveform elements at which the ink droplet velocity reaches its maximum value of 460 is determined. INT1 and the time interval t between waveform elements where the ink droplet velocity reaches a maximum value. INT2 the time interval T between waveform elements c It can be determined as:

[0242] The maximum value of ink droplet velocity may be derived using a method other than measurement using an actual device. For example, it may be determined in advance using a simulation. As with the optimization of the multi-pulse driving waveform, a trained learning model may also be applied to derive the time interval between waveform elements.

[0243] The vertical axis of the graph shown in Figure 18 may represent the volume of the ink droplet instead of the velocity of the ink droplet. The ink consumption of the inkjet head may be used as a method for measuring the volume of the ink droplet using an actual machine.

[0244] [Effects of the Fifth Embodiment] The jetting condition determination method according to the fifth embodiment makes it possible to automatically and comprehensively create optimal drive waveforms for various inks and various jetting conditions, etc. This eliminates the need for know-how in creating drive waveforms, and makes it possible to provide inkjet printing systems and inkjet heads to a wide range of users.

[0245] Furthermore, from the viewpoint of development of inkjet printing systems and inkjet heads, efficient and reliable development becomes possible.

[0246] Each of the jetting condition determination methods according to the first embodiment to the fifth embodiment is an example of a printing condition determination method.

[0247] [Combination of each embodiment] The first to fifth embodiments described above may be combined as appropriate. For example, the test pattern image of the third embodiment may be applied to the first embodiment.

[0248] [Application example to discharge control device] The inkjet printing apparatus applied to the first to fifth embodiments is equipped with a discharge control device that controls ink discharge from the inkjet head. For example, the discharge control device may be configured to include a system control unit 100, a jetting control unit 106, a scan data analysis unit 122, a discharge detection unit 124, a jetting condition setting unit 126, and a memory 130 shown in FIG.

[0249] The discharge control device is implemented by a computer, which executes various programs such as a jetting control program 226 and a jetting condition setting program 238 shown in Fig. 7 to realize various functions of the discharge control device.

[0250] Each processing unit of the discharge control device executes various programs to perform each step included in the jetting condition determination method whose procedure is shown in FIG.

[0251] [Terminology] The term "printing device" is synonymous with terms such as printing press, printer, printing device, image recording device, image forming device, image output device, and drawing device. The term "image" should be interpreted in a broad sense, and includes color images, black and white images, single-color images, gradation images, and uniform density images.

[0252] The term printing includes concepts such as image recording, image formation, printing, drawing, and printing. The term apparatus may include concepts such as a system.

[0253] The term "image" is used as a comprehensive term that includes not only photographic images but also designs, characters, symbols, line drawings, mosaic patterns, colored patterns, and various other patterns, as well as appropriate combinations of these. The term "image" may also include the meaning of image signals and image data that represent an image.

[0254] The above-described embodiments of the present invention may be modified, added, or deleted as appropriate within the scope of the spirit of the present invention. The present invention is not limited to the above-described embodiments, and many modifications may be made by a person skilled in the art within the technical concept of the present invention. Furthermore, the embodiments, modifications, and applications may be implemented in appropriate combinations. [Explanation of symbols]

[0255] 1. Film substrate 1A Printing surface 1B Base material support surface 10 Inkjet Printing System 12 Paper feeder 14 Precoat device 16 Jetting Device 18 Drying equipment 20 Inspection equipment 22 Recovery device 24 Conveyor equipment 30 Inkjet head 30C inkjet head 30K inkjet head 30M inkjet head 30W inkjet head 30Y inkjet head 32 Scanner 34 Pass Roller 36 Tension Pickup 40 Head Module 42 Support frame 44 Flexible PCB 46 Nozzle surface 46A Nozzle forming area 48 Nozzle Plate 50 Ink supply chamber 52 Ink circulation chamber 54 Individual supply flow path 56 Individual recovery flow path 60 Ink supply path 62 Individual supply route 64 Pressure Chamber 66 Nozzle connecting passage 68 Individual circulation flow path 70 Common circulation flow path 72 Piezoelectric element 74 Diaphragm 76 Flow path structure 78 Nozzle section 80 nozzle opening 82 Adhesive layer 84 Lower electrode 86 Piezoelectric layer 88 Upper electrode 90 Circulation outlet 100 System control unit 102 Transport control unit 104 Precoat control unit 106 Jetting control section 108 Drying control unit 110 Inspection control section 112 Scan control section 120 Image data processing unit 122 Scan Data Analysis Unit 124 Discharge detection unit 126 Jetting condition setting section 130 memory 130A Jetting condition memory section 132 sensors 140 Scan data acquisition unit 142 Indicator calculation section 144 Jetting condition acquisition unit 146 Jetting condition determination unit 148 Jetting condition output section 200 control device 202 processors 204 Computer-readable medium 206 Communication Interface 208 Input / Output Interface 210 Bus 214 Input Device 216 Display device 220 Transport Control Program 222 Precoat Control Program 224 Image Data Processing Program 226 Jetting Control Program 228 Drying Control Program 230 Inspection Control Program 232 Scan Control Program 234 Scan Data Analysis Program 236 Discharge Detection Program 238 Jetting Condition Setting Program 300 Print media 302 Tip area 304 test pattern images 304A First test pattern image 304B Second test pattern image 304C Third test pattern image 305 Posterior end area 306 Printed Images 308 Tip 309 Rear end 310 Pattern Elements 310A Pattern Elements 312 yen 400 Multi-pulse drive waveform 402 1st waveform element 404 Second wave element 406 Third wave element 408 4th wave element 410 5th wave element 440 images 442 cropped images 444 Binarized Image 446 White area 460 First maximum 462 Second maximum Each step from step S10 to step S20 Each step of the jetting condition determination method

Claims

1. one or more processors; one or more memories in which programs to be executed by the one or more processors are stored; Equipped with The one or more processors execute instructions of the program, Acquire a first printing condition including one or more printing parameters, the first printing condition including a plurality of printing conditions different from each other; performing continuous printing, in which two or more prints are applied, multiple times by applying different printing conditions using an inkjet head to which any of the plurality of printing conditions included in the first printing condition is applied; measuring the ejection state of the inkjet head two or more times for each of the plurality of continuous printings; analyzing the ejection state of the inkjet head for each of the plurality of continuous printings using the measurement results obtained in each of the two or more measurements; and deriving a printing condition determination index representing a continuous change in the ejection state of the inkjet head for each of the plurality of continuous printings using the analysis results of the ejection state of the inkjet head for each of the plurality of continuous printings; a discharge control device that evaluates each of the plurality of printing conditions included in the first printing conditions using the printing condition determination index for each of the printing conditions;

2. The one or more processors: The discharge control device according to claim 1 , wherein the print condition determination index is derived by performing statistical processing on the analysis results of each of the plurality of consecutive printing operations.

3. The ejection control device according to claim 2 , wherein the one or more processors derive, as the printing condition determination index, a standard deviation of ejection position errors for each nozzle of the inkjet head in each of the plurality of consecutive printings.

4. The one or more processors: calculating an arithmetic average of the printing condition determination index derived for each of the plurality of consecutive printings; The discharge control device according to claim 2 , wherein the arithmetic mean of the printing condition determination index is used to evaluate each of the plurality of printing conditions included in the first printing condition.

5. The one or more processors: selecting the worst printing condition determination index from the printing condition determination indexes calculated for each of the plurality of consecutive printings; The discharge control device according to claim 1 , wherein the selected printing condition determination index is used to evaluate each of the plurality of printing conditions included in the first printing condition.

6. The discharge control device according to claim 1 , wherein the one or more processors calculate a score representing an evaluation of the printing condition determination index.

7. 7. The ejection control device according to claim 1, wherein the one or more processors acquire, as the printing parameter, one of a plurality of printing conditions included in the first printing conditions, the printing conditions including at least one of a drive waveform, an amplitude of a drive voltage, and a pressure applied to an air-liquid interface in a nozzle portion provided in the inkjet head.

8. The ejection control device according to claim 1 , wherein the one or more processors derive the printing condition determination index that indicates a change in ejection deflection of the inkjet head during each of the plurality of consecutive printings.

9. The one or more processors: reading a test pattern image printed using any one of the plurality of printing conditions included in the first printing condition, and generating read data of the test pattern image; The ejection control device according to claim 1 , wherein the read data is used to measure an ejection state of the inkjet head.

10. 10. The ejection control device according to claim 9, wherein any one of the plurality of printing conditions included in the first printing conditions when printing the test pattern image includes at least one of a drive waveform that promotes the occurrence of ejection abnormalities and an amplitude of a drive voltage that promotes the occurrence of ejection abnormalities.

11. The ejection control device according to claim 1 , wherein the one or more processors derive the printing condition determination index that represents a quantitative value of the ink mist adhering to the ejection surface of the inkjet head.

12. One or more processors; one or more memories in which programs to be executed by the one or more processors are stored; Equipped with The one or more processors execute instructions of the program, obtaining a first printing condition including one or more printing parameters; performing continuous printing in which two or more prints are applied using an inkjet head to which the first printing condition is applied; measuring the ejection state of the inkjet head during the continuous printing at least twice; analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing, the printing condition determination index representing a quantitative value of ink mist adhering to the ejection surface of the inkjet head; A discharge control device that evaluates the first printing condition using the printing condition determination index.

13. The discharge control device according to claim 1 , wherein the one or more processors determine second printing conditions to replace the first printing conditions based on the evaluation result of the first printing conditions.

14. the one or more memories store a plurality of drive waveform elements that constitute a drive waveform; The ejection control device according to claim 13 , wherein the one or more processors generate a drive waveform that combines two or more of the drive waveform elements from the plurality of stored drive waveform elements as the printing parameters included in the second printing condition.

15. The one or more processors: applying the second printing condition to carry out the continuous printing; measuring the ejection state of the inkjet head during the continuous printing at least twice; analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing, the printing condition determination index corresponding to the second printing condition; The discharge control device according to claim 13 or 14, wherein the second printing condition is evaluated using a printing condition determination index corresponding to the second printing condition.

16. An ejection control device described in any one of claims 13 to 15, wherein the one or more processors compare a printing condition determination index derived by applying the first printing condition with a printing condition determination index derived by applying the second printing condition, and determine a printing condition corresponding to a good printing condition determination index as the printing condition to be applied to the continuous printing.

17. One or more processors; one or more memories in which programs to be executed by the one or more processors are stored; Equipped with The one or more processors execute instructions of the program, obtaining a first printing condition including one or more printing parameters; performing continuous printing in which two or more prints are applied using an inkjet head to which the first printing condition is applied; measuring the ejection state of the inkjet head during the continuous printing at least twice; analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing; evaluating the first printing condition using the printing condition determination index; determining second printing conditions to replace the first printing conditions based on the evaluation results of the first printing conditions; An ejection control device that compares a printing condition determination index derived by applying the first printing condition with a printing condition determination index derived by applying the second printing condition, and determines the printing condition that corresponds to a good printing condition determination index as the printing condition to be applied to the continuous printing.

18. an inkjet head that ejects ink; a discharge control device that controls ink discharge from the inkjet head; 1. An inkjet printing system comprising: The discharge control device includes: one or more processors; one or more memories in which programs to be executed by the one or more processors are stored; Equipped with The one or more processors execute instructions of the program, Acquire a first printing condition including one or more printing parameters, the first printing condition including a plurality of printing conditions different from each other; applying any of the plurality of printing conditions included in the first printing conditions to the inkjet head, and performing continuous printing, in which two or more prints are applied, multiple times by applying different printing conditions using the inkjet head; measuring the ejection state of the inkjet head two or more times for each of the plurality of continuous printings; analyzing the ejection state of the inkjet head for each of the plurality of continuous printings using the measurement results obtained in each of the two or more measurements; and deriving a printing condition determination index representing a continuous change in the ejection state of the inkjet head for each of the plurality of continuous printings using the analysis results of the ejection state of the inkjet head for each of the plurality of continuous printings; an inkjet printing system that evaluates each of the plurality of printing conditions included in the first printing condition set using the printing condition determination index for each of the printing conditions;

19. An inkjet head that ejects ink; a discharge control device that controls ink discharge from the inkjet head; 1. An inkjet printing system comprising: The discharge control device includes: one or more processors; one or more memories in which programs to be executed by the one or more processors are stored; Equipped with The one or more processors execute instructions of the program, obtaining a first printing condition including one or more printing parameters; performing continuous printing in which two or more prints are applied using an inkjet head to which the first printing condition is applied; measuring the ejection state of the inkjet head during the continuous printing at least twice; analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing, the printing condition determination index representing a quantitative value of ink mist adhering to the ejection surface of the inkjet head; an inkjet printing system that evaluates the first printing condition using the printing condition determination index;

20. An inkjet head that ejects ink; a discharge control device that controls ink discharge from the inkjet head; 1. An inkjet printing system comprising: The discharge control device includes: one or more processors; one or more memories in which programs to be executed by the one or more processors are stored; Equipped with The one or more processors execute instructions of the program, obtaining a first printing condition including one or more printing parameters; performing continuous printing in which two or more prints are applied using an inkjet head to which the first printing condition is applied; measuring the ejection state of the inkjet head during the continuous printing at least twice; analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing; evaluating the first printing condition using the printing condition determination index; determining second printing conditions to replace the first printing conditions based on the evaluation results of the first printing conditions; An inkjet printing system that compares a printing condition determination index derived by applying the first printing condition with a printing condition determination index derived by applying the second printing condition, and determines a printing condition that corresponds to a good printing condition determination index as the printing condition to be applied to the continuous printing.

21. The computer acquiring first printing conditions including one or more printing parameters for printing using an inkjet head, the first printing conditions including a plurality of printing conditions different from each other; applying any one of the plurality of printing conditions included in the first printing condition to the inkjet head, and performing continuous printing, in which two or more prints are applied, multiple times by applying different printing conditions using the inkjet head; measuring the ejection state of the inkjet head during the continuous printing at least twice; analyzing the ejection state of the inkjet head for each of the plurality of continuous printings using the measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head for each of the plurality of continuous printings using the analysis results of the inkjet head for each of the plurality of continuous printings; A printing condition determination method for evaluating each of the plurality of printing conditions included in the first printing conditions using the printing condition determination index for each of the printing conditions.

22. A computer comprising: obtaining a first printing condition including one or more printing parameters; performing continuous printing in which two or more prints are applied using an inkjet head to which the first printing condition is applied; measuring the ejection state of the inkjet head during the continuous printing at least twice; analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing, the printing condition determination index representing a quantitative value of ink mist adhering to the ejection surface of the inkjet head; A printing condition determination method for evaluating the first printing condition using the printing condition determination index.

23. A computer comprising: acquiring a first printing condition including one or more printing parameters in printing to which the inkjet head is applied; performing continuous printing in which two or more prints are applied using an inkjet head to which the first printing condition is applied; measuring the ejection state of the inkjet head during the continuous printing at least twice; analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing; evaluating the first printing condition using the printing condition determination index; determining second printing conditions to replace the first printing conditions based on the evaluation results of the first printing conditions; A printing condition determination method that compares a printing condition determination index derived by applying the first printing condition with a printing condition determination index derived by applying the second printing condition, and determines a printing condition that corresponds to a good printing condition determination index as the printing condition to be applied to the continuous printing.

24. On the computer, a function of acquiring first printing conditions including one or more printing parameters for printing using an inkjet head, the first printing conditions including a plurality of printing conditions different from each other; a function of applying a first printing condition to the inkjet head, and using the inkjet head to perform continuous printing, in which two or more prints are applied, multiple times by applying different printing conditions; a function of measuring the ejection state of the inkjet head two or more times for each of the plurality of continuous printings; a function of analyzing the ejection state of the inkjet head for each of the plurality of consecutive printings using measurement results obtained in each of the two or more measurements, and deriving, for each of the printing conditions, a printing condition determination index that represents a continuous change in the ejection state of the inkjet head using the analysis results of the ejection state of the inkjet head for each of the plurality of consecutive printings; and a program for realizing a function of evaluating each of the plurality of printing conditions included in the first printing conditions using the printing condition determination index for each of the printing conditions;

25. A computer comprising: acquiring a first printing condition including one or more printing parameters; a function of performing continuous printing in which two or more prints are applied using an inkjet head to which the first printing condition is applied; a function of measuring the ejection state of the inkjet head during the continuous printing at least twice; a function of analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing, the printing condition determination index representing a quantitative value of ink mist adhering to the ejection surface of the inkjet head; and a program for realizing a function of evaluating the first printing condition using the printing condition determination index;

26. A computer comprising: acquiring a first printing condition including one or more printing parameters; a function of performing continuous printing in which two or more prints are applied using an inkjet head to which the first printing condition is applied; a function of measuring the ejection state of the inkjet head during the continuous printing at least twice; a function of analyzing the ejection state of the inkjet head using two or more measurement results obtained in each of the two or more measurements, and deriving a printing condition determination index that represents a continuous change in the ejection state of the inkjet head during the continuous printing; a function of evaluating the first printing condition using the printing condition determination index; a function of determining a second printing condition to replace the first printing condition based on the evaluation result of the first printing condition; and A program that realizes the function of comparing a printing condition determination index derived by applying the first printing condition with a printing condition determination index derived by applying the second printing condition, and determining the printing condition corresponding to the good printing condition determination index as the printing condition to be applied to the continuous printing.

Images