JP7796541B2 - Discharge control device, inkjet printing system, printing condition determination method and program - Google Patents

Description

The present invention relates to an ejection control device, an inkjet printing system, a printing condition determination method, and a program.

Printing devices that use inkjet heads require optimization of printing conditions, such as the drive waveform used to drive the inkjet head. Printing devices that use 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.

It is known that the optimal drive waveform for inkjet heads varies depending on individual differences caused by differences in the resistance of the internal flow paths, etc. It is also known that the amplitude of the drive voltage suitable for stable ejection varies depending on the ink used.

For example, the drive waveform and drive voltage amplitude are designed in advance, and the flight state and amount of ejection deflection are evaluated and determined in advance. Furthermore, 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 the ejection position error.

Patent Document 1 describes an inkjet printing device that corrects printing conditions based on the print results. The device described in this document reads the 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.

JP 2012-60596 A

However, if only one type of optimized drive waveform is maintained, it becomes difficult to adjust according to the ejection state of each inkjet head, and there is a risk that the ejection stability of the inkjet head will decrease. If large volumes of printing are carried out continuously using an inkjet head with reduced ejection stability, defects such as streaks may occur in the printed image.

Furthermore, when the driving voltage is adjusted using a specified chart to maintain a consistent density for the printed image, 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 deteriorated.

In inkjet heads that selectively use multiple droplet sizes, such as large, medium, and small droplets, the size ratio between droplet sizes may vary depending on individual differences in the inkjet head.

As a result, 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, the amplitude of the driving voltage may not be optimized from the perspective of ejection stability.

Patent Document 1 describes how ejection abnormalities such as non-ejection and deflected ejection are inspected, and printing conditions are corrected or inkjet head maintenance is performed. However, it does not address the issue of continuous changes in ejection conditions, such as changes over time in the ejection state during continuous printing. The device described in this document makes it difficult to guarantee the ejection stability that is important in actual continuous printing.

The present invention was made in light of these circumstances, and aims to provide a discharge control device, inkjet printing system, printing condition determination method, and program that enable adjustments that can achieve stable discharge from inkjet heads during continuous printing.

To achieve the above objectives, the following invention aspects are provided.

The ejection 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. The one or more processors execute instructions from the program to obtain first printing conditions including one or more printing parameters, perform continuous printing with two or more print runs using an inkjet head to which the first printing conditions are applied, measure the ejection status of the inkjet head two or more times during the continuous printing, analyze the ejection status 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 status of the inkjet head during the continuous printing, and evaluate the first printing conditions using the printing condition determination index.

The ejection control device disclosed herein evaluates the first printing conditions during continuous printing in which the first printing conditions are applied using a printing condition determination index derived based on two or more measurement results of the ejection state of the inkjet head, which index represents 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.

An inkjet head has multiple nozzles that eject ink. An inkjet head can have a structure in which multiple head modules are arranged.

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

This aspect makes it possible to grasp continuous changes in the ejection state of an inkjet head during continuous printing.

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

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

In another aspect of the discharge control device, one or more processors may perform multiple consecutive prints, calculate an arithmetic mean of the print condition determination index derived for each consecutive print, and evaluate the first print condition using the arithmetic mean of the print condition determination index.

According to this aspect, the statistical processing can involve calculating the arithmetic mean of the printing condition determination index derived for each of multiple consecutive printing runs.

In another aspect of the ejection control device, one or more processors may calculate the printing condition determination index using measurement results of the ejection status of the inkjet head obtained during multiple consecutive printing runs.

This aspect makes it possible to grasp continuous changes in the ejection state of the inkjet head over multiple consecutive print runs.

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 the multiple consecutive printing runs, and evaluate the first printing conditions using the selected printing condition determination index.

This aspect makes it possible to grasp continuous changes in the ejection state of the inkjet head over multiple consecutive print runs.

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

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

In another aspect of the ejection control device, one or more processors may acquire first printing conditions as printing parameters, which include 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 of the inkjet head.

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 of the inkjet head.

In another aspect of the ejection control device, one or more processors may derive a printing condition determination index that represents changes in the ejection deflection of the inkjet head during continuous printing.

According to this aspect, the first printing conditions can be evaluated based on changes in the inkjet head's ejection deflection during continuous printing.

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

According to this aspect, the ejection status of the inkjet head can be measured based on the scanned data of the test pattern image printed using the first printing conditions.

In another aspect of the ejection control device, the first printing conditions for printing the test pattern image may include at least one of a drive waveform that promotes the occurrence of ejection abnormalities and a drive voltage amplitude that promotes the occurrence of ejection abnormalities.

This aspect can promote the occurrence of ejection abnormalities in inkjet heads with unstable ejection conditions.

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

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.

In another aspect of the discharge control device, 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.

This aspect makes it possible to set printing conditions that enable inkjet heads to continuously eject ink in a stable state during continuous printing.

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

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

In another aspect of the ejection control device, one or more processors may apply second printing conditions, 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 corresponding to the second printing conditions, which is a printing condition determination index that represents continuous changes in the ejection state of the inkjet head during the continuous printing, and evaluate the second printing conditions using the printing condition determination index corresponding to the second printing conditions.

This aspect allows the printing conditions to be changed sequentially to determine the best printing conditions.

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

This aspect makes it possible to dynamically change printing conditions and derive optimal printing conditions.

The inkjet printing system according to the present disclosure is an inkjet printing system comprising an inkjet head that ejects ink and an ejection control device that controls the ink ejection from the inkjet head. The ejection control device comprises one or more processors and one or more memories that store a program to be executed by the one or more processors. 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, and perform continuous printing using the inkjet head with two or more print runs. The inkjet printing system measures the ejection status of the inkjet head two or more times during the continuous printing, analyzes the ejection status of the inkjet head using two or more measurement results obtained from each of the two or more measurements, derives a printing condition determination index that represents continuous changes in the ejection status of the inkjet head during the continuous printing, and evaluates the first printing conditions using the printing condition determination index.

The inkjet printing system according to the present disclosure can achieve the same effects as the discharge control device according to the present disclosure. The constituent elements of the discharge control device according to other aspects can also be applied to the constituent elements of the inkjet printing system according to other aspects.

The printing condition determination method disclosed herein is a printing condition determination method in which a computer acquires first printing conditions including one or more printing parameters for printing using an inkjet head, applies the first printing conditions to the inkjet head, performs continuous printing using the inkjet head for two or more print runs, measures the ejection state of the inkjet head two or more times during the continuous printing, analyzes the ejection state of the inkjet head using two or more measurement results obtained from 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 during the continuous printing, and evaluates the first printing conditions using the printing condition determination index.

The printing condition determination method according to the present disclosure can achieve the same effects as the discharge control device according to the present disclosure. The constituent elements of the discharge control device according to other aspects can also be applied to the constituent elements of the printing condition determination method according to other aspects.

The program disclosed herein causes a computer to perform the following functions: acquire first printing conditions including one or more printing parameters for printing using an inkjet head; apply the first printing conditions to the inkjet head and perform continuous printing using the inkjet head for two or more print runs; measure the ejection state of the inkjet head two or more times during 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 to derive a printing condition determination index that represents continuous changes in the ejection state of the inkjet head during continuous printing; and evaluate the first printing conditions using the printing condition determination index.

The program according to the present disclosure can achieve the same effects as the discharge control device according to the present disclosure. The constituent elements of the discharge control device according to other aspects can also be applied to the constituent elements of the program according to other aspects.

According to the present invention, in continuous printing in which first printing conditions are applied, the first printing conditions are evaluated using a printing condition determination index derived based on two or more measurement results of the inkjet head's ejection state, which index represents continuous changes in the inkjet head's ejection state. This makes it possible to derive a printing condition determination index that can achieve inkjet head ejection stability in continuous printing.

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

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In this specification, identical components will be designated by the same reference numerals, and duplicate descriptions will be omitted where appropriate.

[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 show 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.

The actual substrate transport direction for each device is the direction in which the film substrate 1 travels, and is the direction along the traveling direction of the film substrate 1. In other words, the arrows shown in Figure 1 indicate that in the inkjet printing system 10, the film substrate 1 travels through the paper feed device 12, precoat device 14, jetting device 16, drying device 18, and inspection device 20 in that order.

The inkjet printing system 10 is a printing system that uses a single-pass method and prints color images on a film substrate 1 using water-based color inks. The film substrate 1 is a transparent, non-permeable medium used for flexible packaging.

Examples of film substrate 1 include ONY (Oriented Nylon), OPP (Oriented Polypropylene), and PET (PolyEthylene Terephthalate). Inkjet printing system 10 produces reverse-printed prints that are visible from substrate support surface 1B, the side of film substrate 1 opposite printing surface 1A. Inkjet printing system 10 can also produce front-printed prints that are visible from printing surface 1A.

"Non-permeable" means that the material is non-permeable to the water-based primer and water-based ink described below. "Flexible packaging" means packaging made of a material that deforms depending on the shape of the packaged item. "Transparent" means that the visible light transmittance is between 30% and 100%, preferably between 70% and 100%.

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 recovery device 22, and a conveying device 24. Each component is described in detail below.

[Paper feeding device]
A roll-to-roll transport system is applied to the inkjet printing system 10. The paper feed device 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.

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 printing surface 1A of the modified film substrate 1 has a surface free energy suitable for the aqueous mixture of the aqueous primer and aqueous ink, ensuring wettability suitable for the aqueous mixture. The film substrate 1 is transported to the precoater 14.

[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.

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 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.

[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.

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 heads 30.

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. 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.

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

The inkjet head 30 ejects color ink 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.

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

While Figure 1 shows an embodiment in which four water-based inks of different colors are used, the ink colors are not limited to black, cyan, magenta, and yellow. For example, it is also possible to use light-colored inks such as light magenta and light cyan, or special-color inks such as green, orange, violet, clear, and metallic. Furthermore, the arrangement order of the inkjet heads of each color is not limited to the example shown in Figure 1.

The jetting device 16 is equipped with a scanner 32. The scanner 32 has an imaging device that captures the test pattern image printed on the printing surface of the film substrate 1 and converts the captured image into an electrical signal.

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

The image data output from the scanner 32 is sent to a 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 a test pattern image described in the embodiment is an example of reading a 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.

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

The inspection device 20 is equipped with an imaging device that captures the 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. After the printed image inspection has been carried out, the film substrate 1 is transported to the collection device 22.

[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.

[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 conveying path in the substrate conveying direction from the paper feeding device 12 to the recovery device 22, in the order 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. The paper feeding device 12 and the recovery device 22 may be included in the conveying device 24.

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, precoating device 14, jetting device 16, drying device 18, inspection device 20, and recovery device 22.

The conveying device 24 includes one or more tension pickups 36 arranged in each of the paper feeder 12, precoater 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. The detection signal from the tension pickups 36 is sent to the conveying control unit. The conveying control unit is illustrated in Figure 5 using the reference numeral 102. Figure 1 shows the tension pickup 36 provided in the jetting device 16, but does not show the tension pickups 36 provided in the paper feeder 12, etc.

In this embodiment, the conveying device 24 is exemplified as applying a continuous roll-to-roll method, but the conveying device 24 may also apply a method in which sheets are taken out one by one from a stocker and conveyed.

In addition, the conveying device 24 may be equipped with a conveying mechanism such as a conveying belt and a conveying drum instead of multiple pass rollers 34. Furthermore, the conveying device 24 may combine an embodiment equipped with multiple pass rollers 34 with an embodiment equipped with a conveying belt, etc.

The film substrate 1 is not limited to a transparent substrate. An opaque substrate with a visible light transmittance of less than 30 percent may also be used. Substrates such as paper, cloth, and film-like metal substrates may also be used instead of the film substrate 1.

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

Each head module 40 is connected to two flexible substrates 44. The flexible substrates 44 have electrical wiring formed thereon that transmits the drive voltage supplied to the ejection elements provided in the head module 40.

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

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

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 illustration.

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

The ink supply channels 60, individual supply channels 62, pressure chambers 64, nozzle connection 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 connection channel 66. The nozzle connection channel 66 is a channel that constitutes an ejection element, and corresponds to the channel that communicates with the nozzle opening 80.

The individual supply channels 62 are flow paths that connect the pressure chambers 64 and the ink supply channels 60. The nozzle connection channels 66 are flow paths that connect the pressure chambers 64 and the nozzle openings 80. The individual circulation channels 68 are flow paths that connect the nozzle connection channels 66 and the common circulation channel 70.

A vibration plate 74 is placed on the flow path structure 76. A piezoelectric element 72 is placed 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.

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 equipped with a piezoelectric element 72. The piezoelectric element 72 corresponds to the energy generating element that constitutes the ejection element.

The ink supply channel 60 communicates with the ink supply chamber 50 shown in Figure 3. Ink is supplied from the ink supply channel 60 to the pressure chamber 64 via the individual supply channel 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 diaphragm 74 to deform and changing the volume of the pressure chamber 64. The head module 40 ejects ink droplets from the nozzle opening 80 via the nozzle communication channel 66 in response to pressure changes caused by changes in the volume of the pressure chamber 64.

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 channel 62, which is 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, including rhombus, quadrangles such as rectangles, pentagons, hexagons or other polygons, circles, and ellipses.

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.

The common circulation flow path 70 communicates with the ink circulation chamber 52 shown in Figure 3. 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 portion 78 from thickening during non-ejection periods.

Figure 4 illustrates an example of a piezoelectric element 72 having a structure that is individually separated to correspond to each of the multiple nozzle portions 78. Of course, a structure in which a piezoelectric layer 86 is formed integrally with the multiple nozzle portions 78, individual electrodes are formed to correspond to each of the multiple nozzle portions 78, and an active region is formed for each nozzle portion 78 may also be applied.

The nozzle openings 80 on the nozzle surface 46 are arranged two-dimensionally. 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 figures. A water-repellent film may be formed on the nozzle surface 46.

Figure 4 illustrates a head module 40 equipped with a piezoelectric element 72 as an energy generating element, but a heater may also be used as the energy generating element. An inkjet head 30 equipped with a heater ejects ink droplets from the nozzle openings 80 by utilizing the film boiling phenomenon of ink.

[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.

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.

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 with a single device divided into multiple areas.

The inkjet printing system 10 includes a transport control unit 102, a precoat control unit 104, a jetting control unit 106, a drying control unit 108, an inspection control unit 110, and a scan control unit 112.

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 be applied to the transport device 24 and controls the operation of motors connected to drive rollers and other components provided in the transport device 24.

The precoat control unit 104 sets the processing conditions for the precoat process based on command signals sent from the system control unit 100 and controls the operation of the precoat device 14 based on the set processing conditions.

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

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. The drive waveform can be stored in memory 130.

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 converter that converts digital drive waveforms into analog format, and a power amplifier. The drive voltage output unit applies a specified ejection cycle and selectively outputs a drive voltage for each nozzle.

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

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

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 sent from the scanner 32 and stores the scan data. Memory 130 may be used to store the scan data.

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 process, 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.

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 in the inkjet head 30.

The ejection detection unit 124 detects whether ejection has occurred, whether ejection is deflected, and whether abnormalities in the ink ejection volume have occurred for each inkjet head 30 and each nozzle based on the analysis results of the scan data analysis unit 122.

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

The jetting conditions may include the amplitude, drive waveform, and back pressure of the drive voltage supplied to the inkjet head 30. 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.

The jetting condition setting unit 126 stores the jetting conditions. The jetting conditions can be stored in memory 130. Details of the jetting conditions and how they are set will be described later.

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

The inkjet printing system 10 is equipped with a sensor 132. The system control unit 100 acquires a sensor signal transmitted from the sensor 132 and transmits command signals based on the sensor signal to various control units. The sensor 132 shown in Figure 5 includes a position detection sensor and a temperature sensor, etc., which are provided in each part of the inkjet printing system shown in Figure 1.

Figure 6 is a functional block diagram of the jetting condition setting unit shown in Figure 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 amount of ejection deflection, which represents the ejection position error for each inkjet head 30 and each nozzle. Note that the scan data described in this embodiment is an example of read data for a test pattern image.

The index calculation unit 142 uses the amount of ejection deflection for each inkjet head 30 and each nozzle to calculate a jetting condition determination index that represents the ejection stability for each inkjet head 30 and each nozzle during continuous printing.

The jetting condition determination index may be the standard deviation σ _t of the amount of deflection of the ejection, which indicates the variation in the amount of deflection of the ejection for each nozzle. The standard deviation σ _t of the amount of deflection of the ejection may be calculated by the following procedure.

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, the multiple amounts of ejection deflection of each nozzle are statistically processed, and the standard deviation σ _t of the amount of ejection deflection is calculated as an index for determining the jetting condition.

The standard deviation σ _t of the amount of ejection deflection is associated with the jetting conditions and stored. The memory 130 shown in FIG. 5 is used to store the standard deviation σ _t of the amount of ejection deflection associated with the jetting conditions.

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 used to calculate the jetting condition determination index. The jetting condition determination unit 146 evaluates the standard deviation σ _t of the ejection deflection amount calculated using the index calculation unit 142 for each jetting condition, and determines the optimal jetting conditions for each inkjet head 30 based on the evaluation results. The jetting conditions include the drive waveform and the amplitude of the drive voltage.

The jetting condition setting unit 126 outputs the 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 memory unit 130A. When determining the jetting conditions, the jetting condition setting unit 126 reads the jetting conditions corresponding to the scan data from the jetting condition memory unit 130A. The jetting condition memory unit 130A can be included in the memory 130 shown in FIG. 5.

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 computer-readable medium 204, a communication interface 206, and an input/output interface 208.

The control device 200 is implemented as a computer. 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.

The processor 202 includes a CPU (Central Processing Unit). The processor 202 may also include a GPU (Graphics Processing Unit). 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.

The computer-readable medium 204 includes memory, which is a primary storage device, and storage, which is a secondary 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.

Hard disk devices may be referred to as HDDs, which are an abbreviation for Hard Disk Drives. Solid state drive devices may be referred to as SSDs, which are an abbreviation for Solid State Drives.

The control device 200 is connected to a network via the communication interface 206 and is communicatively connected to external devices. The network may be a LAN (Local Area Network) or the like. The network is not shown in the figure.

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.

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 the image processing applied to the image data processing unit 120. The jetting control program 226 corresponds to the jetting control applied to the jetting control unit 106.

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.

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.

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

The jetting condition setting program 238 may include an index calculation program and a jetting condition determination program. The index calculation program and jetting condition determination program are not shown in the figures.

The various programs stored on the computer-readable medium 204 contain one or more instructions. The computer-readable medium 204 stores various data, parameters, and the like. Note that the memory 130 shown in FIG. 2 is included in the computer-readable medium 204 shown in FIG. 3.

In the inkjet printing system 10, the processor 202 executes various programs stored on 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."

The control device 200 communicates data with external devices via the communication interface 206. The communication interface 206 may use various standards, such as USB (Universal Serial Bus). The communication form of the communication interface 206 may be either wired or wireless.

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 an input device such as a keyboard or mouse. The display device 216 displays various information applied to the control device 200.

The display device 216 may be a liquid crystal display, an organic EL display, a projector, or the like. Any combination of multiple devices may be used as the display device 216. Note that the "EL" in organic EL display is an abbreviation for Electro-Luminescence.

Here, examples of the hardware structure of the processor 202 include a CPU, GPU, PLD (Programmable Logic Device), and 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.

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 specific tasks.

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

Multiple functional units may be configured using a single processor. An example of using a single processor to configure multiple functional units is a system on a chip (SoC), such as a client or server computer, where a single processor is configured by combining one or more CPUs with software, and the processor then functions as multiple functional units.

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

In this way, the various functional units are configured as a hardware structure using one or more of the various processors described above. Furthermore, the hardware structure of the various processors described above is, more specifically, an electrical circuit (circuitry) that combines circuit elements such as semiconductor devices.

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 magnetic storage media such as a hard disk. The computer-readable medium 204 may comprise multiple types of storage media.

[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.

The jetting condition determination method, the steps of which are shown in FIG. 8, calculates the standard deviation _σt of the jetting deflection, which represents the variation in the jetting deflection during continuous printing, for a plurality of predefined jetting conditions, and determines the drive waveform and drive voltage amplitude that minimize the standard deviation _σt of the jetting deflection as the optimal jetting conditions.

In the jetting condition setting process S10, the jetting conditions to be applied to continuous printing are set using the jetting condition setting unit 126 shown in Figure 5. For example, the initial conditions pre-set in the inkjet printing system 10 are set. After the jetting condition setting process S10, the process proceeds to the continuous printing process S12.

Note that in the jetting condition setting process S10 described in the embodiment, the jetting conditions set as the evaluation targets are an example of first printing conditions.

In the continuous printing process S12, the jetting control unit 106 performs continuous printing on multiple sheets, and the scanner 32 is used to obtain scan data of the test pattern image to be printed on each sheet. The test pattern image is illustrated in Figure 9 with the reference numeral 304.

A sheet of continuous media means 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.

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.

Note that the continuous printing of multiple sheets described in the embodiment is an example of continuous printing where two or more prints are applied.

An index calculation step S14 is executed during the continuous printing step S12. In the index calculation step S14, an index calculation unit 142 shown in Fig. 6 calculates a standard deviation σt of the amount of ejection deflection, which represents the variation in the amount of ejection deflection during continuous printing, for each inkjet head 30 and for each nozzle, from the amount of ejection _deflection for each nozzle derived using the scan data analysis unit 122 that is successively acquired during continuous printing.

The standard deviation _σt of the amount of ejection deflection for each inkjet head 30 and each nozzle is associated with the jetting condition and stored as a jetting condition determination index. Note that the measurement of the amount of ejection deflection based on scan data acquired sequentially 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 _σt of the amount of ejection deflection, which represents the variation in the amount of ejection deflection during continuous printing described in the embodiment, is an example of a printing condition determination index that represents a continuous change in the ejection state of the inkjet head.

Once the jetting condition determination index is calculated in the index calculation step S14, the jetting condition change determination step S16 is executed. In the jetting condition change determination step S16, the jetting condition setting unit 126 determines whether there are any other jetting conditions to be evaluated.

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, a Yes determination is made. If the Yes determination is made, the process proceeds to the jetting condition setting step S10. Each step from the jetting condition setting step S10 to the jetting condition change determination step S16 is repeatedly executed until the jetting condition change determination step S16 returns a No determination, and jetting condition determination indices are calculated for all jetting conditions to be evaluated.

On the other hand, if the jetting condition setting unit 126 determines in the jetting condition change determination step S16 that jetting condition determination indices 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.

Figure 8 illustrates an example in which the index calculation process S14 and the jetting condition change determination process S16 are performed during 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 when switching between continuous printing.

In the jetting condition determination step S18, the jetting condition determination unit 146 determines, for each inkjet head 30, the jetting conditions that minimize the standard deviation σ _t of the amount of ejection deflection, which is the jetting condition determination index.

In other words, in the jetting condition determination step S18, the jetting condition with the best jetting condition determination index calculated for each of the multiple jetting conditions is determined for each inkjet head 30 as the jetting condition for continuous printing.

After the jetting condition determination step S18, the process proceeds to the continuous printing end determination step S20. The jetting conditions determined as the jetting conditions for continuous printing and having the best jetting condition determination index are an example of second printing conditions.

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 step 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.

On the other hand, if the jetting control unit 106 determines to end continuous printing in the continuous printing end determination step S20, the determination is No. If the determination is No, the procedure for determining jetting conditions is terminated.

Changes to jetting conditions during continuous printing may be made during continuous printing, or may be made during periods when the inkjet head 30 is idle, such as when switching between continuous printing and pausing continuous printing.

In this embodiment, an example has been given in which jetting conditions are determined for each inkjet head 30 based on the jetting condition determination index, but in an inkjet head 30 equipped with multiple head modules 40, jetting conditions can be determined for each head module 40. Furthermore, jetting conditions can also be determined for each nozzle and for each nozzle block including multiple nozzles.

[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.

A test pattern image 304, also known as a ladder pattern or 1-on-N-off pattern, is printed in the leading edge region 302 of the print medium 300. The leading edge region 302 of the print medium 300 is an area where the print image 306 is not printed, and is the area closer to the leading edge 308 of the print medium 300 than the print image 306.

The center of Figure 9 shows an enlarged view of the test pattern image 304 to be printed on the print medium 300 shown in the lower part of Figure 9. The upper part of Figure 9 also shows an enlarged view of a portion of the test pattern image 304 shown in the center of Figure 9.

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 are unable to print pattern elements 310, and pattern elements 310 are not printed at positions corresponding to the non-ejecting nozzles.

In the circle 312, which shows an enlarged view of some of the pattern elements 310 that make up the test pattern image 304, dashed lines are used to schematically illustrate pattern elements 310A that correspond to non-ejecting nozzles and are not printed.

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 can be identified as nozzles with low ejection stability. In this way, the amount of ejection deflection for each nozzle can be calculated, the variation in the amount of ejection deflection for each nozzle can be calculated, and the ejection stability of each nozzle can be evaluated based on the variation in the amount of ejection deflection for each nozzle.

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

Figure 10 is a schematic diagram of a modified test pattern image. The print medium 300 shown in the figure has a first test pattern image 304A printed in the leading edge region 302, a second test pattern image 304B printed in the middle margin region 303, and a third test pattern image 304C printed in the trailing edge region 305.

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.

If the number of times the ejection state of the inkjet head 30 is evaluated increases relatively, the number of printed sheets and the process period will increase, which can increase the processing load. Therefore, when 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.

Figure 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 can be implemented 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 across the entire surface of one sheet of print medium 300.

[Detailed explanation of jetting condition determination index calculation]
Fig. 11 is a graph showing the amount of ejection deflection for each nozzle. The horizontal axis of the graph shown in this figure is the nozzle number, and the vertical axis is the standard deviation, which represents the variation in the amount of ejection deflection. The nozzle numbers are assigned in order, starting with the nozzle at one end as number 1, in a projected nozzle row formed by projecting a plurality of nozzles arranged in a matrix arrangement in the longitudinal direction of the inkjet head 30 and lining up the nozzles in the same direction. Fig. 11 shows an example where the number of nozzles is 900.

The vertical axis of the graph shown in Figure 11 is the normalized value of the 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 discretely placed plots are nozzles with relatively low ejection stability. In this way, the ejection stability of each nozzle can be grasped.

Figure 12 is a graph showing the amount of deflection versus the number of prints for nozzles with stable ejection. Figure 13 is a graph showing the amount of deflection versus the number of prints for nozzles with unstable ejection.

Figure 12 shows the amount of deflection for any one nozzle with a stable ejection state out of the multiple nozzles shown in Figure 11. Figure 13 shows the amount of deflection for any one 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. The amount of deflection is the normalized absolute value of the error from the specified ejection position, and is shown as a ratio to a reference value where the specified reference value is 1.

The nozzles showing the amount of deflected ejection in Figure 12 always maintain a stable ejection state during continuous printing, whereas the nozzles showing the amount of deflected ejection in Figure 13 experience relatively large deflected ejection around the 150th printed page.

When the standard deviation is calculated for the amount of deflection shown in Figures 12 and 13, the nozzles showing the amount of deflection in Figure 12 have a relatively small standard deviation, while the nozzles showing the amount of deflection in Figure 13 have a relatively large standard deviation.

In other words, nozzles with a relatively large standard deviation of the amount of ejection curvature can be judged to have a relatively large variation in the amount of ejection curvature and an unstable ejection state. On the other hand, nozzles with a relatively small standard deviation of the amount of ejection curvature can be judged to have a relatively small variation in the amount of ejection curvature and a stable ejection state.

In this embodiment, the standard deviation of the amount of ejection deflection for each nozzle in one continuous print run was used as an example of statistical processing, but variance may be used instead of standard deviation. Furthermore, the results of statistical processing in multiple continuous print runs may be further statistically processed to calculate an index.

For example, the amount of deflection in each of multiple consecutive print runs may be stored, and the standard deviation may be calculated for all of the deflection in each of the multiple consecutive print runs. Alternatively, the standard deviation for each of the multiple consecutive print runs may be stored, and the arithmetic average of the standard deviations for the multiple consecutive print runs may be calculated. Furthermore, the standard deviation for each of the multiple consecutive print runs may be stored, and the maximum standard deviation may be used as the index.

[Example of a multi-pulse driving waveform]
FIG. 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 represents time in microseconds, and the vertical axis represents voltage in volts.

Figure 14 illustrates a multi-pulse drive waveform 400 including a first wave element 402, a second wave element 404, a third wave element 406, a fourth wave element 408, and a fifth wave element 410. The drive voltage is applied in one or more of the wave elements from the first wave element 402 to the fifth wave element 410.

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. Furthermore, 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.

When optimizing jetting conditions, changes to waveform elements and combinations of waveform elements may be performed. For example, when ejecting a small droplet, the second waveform element 404 may be selected instead of the first waveform element 402.

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

Furthermore, when ejecting large droplets, the first wave element 402 may be deleted from the combination of the first wave element 402 to the fifth wave element 410, and the 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.

[Operation and effect 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.

[1]
During continuous printing, the ejection state of each nozzle provided in 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.

[2]
The amount of deflection of the ink jetting from each nozzle of the inkjet head 30 during continuous printing is statistically processed, and the standard deviation σ _t of the amount of deflection of the ink jetting, which represents the variation in the amount of deflection of the ink jetting, 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 deflection of the ink jetting from each nozzle.

[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.

[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.

[Jeting Condition Determination Method According to 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.

The inkjet printing system 10 according to the first embodiment is applied as the hardware configuration to the jetting condition determination method according to the second embodiment. A description of the hardware will be omitted here.

The steps from the jetting condition setting step S10 to the index calculation step S14 shown in Figure 8 are executed. 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.

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 .

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.

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 , a 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, a jetting condition including the best drive waveform is derived.

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.

A similar procedure to that for the drive waveform can also be used for the amplitude of the drive voltage. For example, the jetting condition determination index is calculated and evaluated with the initial drive voltage amplitude set to 100 percent. The jetting condition determination index is then calculated and evaluated with the drive voltage amplitude set 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.

[Operation and effect 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.

[Jeting Condition Determination Method According to 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 determination indicators for each jetting condition and highlighting unsatisfactory jetting conditions.

The jetting condition determination method according to the third 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.

For example, the test pattern image 304 shown in FIG. 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 made relatively long. For example, if the original length of the pattern element 310 is 0.65 millimeters, the actual length of the pattern element 310 is set to 1.0 millimeters.

This increases the probability that ejection abnormalities will occur in nozzles with unstable ejection states, making it easier to determine whether or not an ejection abnormality is occurring in a nozzle with an unstable ejection state. Note that the drive waveform that increases the probability of ejection abnormalities occurring in nozzles with unstable ejection states described in the embodiment is an example of a drive waveform that promotes the occurrence of ejection abnormalities. Furthermore, the drive voltage amplitude that increases the probability of ejection abnormalities occurring in nozzles with unstable ejection states is an example of a drive voltage amplitude that promotes the occurrence of ejection abnormalities.

[Jeting Condition Determination Method According to 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 state of the inkjet head 30.

Fig. 15 is an image of the nozzle surface captured using a high-speed camera. This figure shows an enlarged view of a portion of the nozzle surface 46 shown in Fig. 2. The captured image 440 shown in Fig. 15 shows a large amount of ink mist _Im adhering to the nozzle formation region 46A of the nozzle surface 46.

Figure 16 is a cropped image obtained by cropping the nozzle formation region from the photographed image of the nozzle surface shown in Figure 15. The cropped image 442 shown in Figure 16 is generated by performing area extraction processing on the photographed image 440 shown in Figure 15. Publicly known image processing techniques can be used for the area extraction processing.

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

As jetting condition determination indicators related to the ink mist I _m adhering to the nozzle surface 46, the volume of the ink mist I _m adhering to the nozzle surface 46 and the slope of the volume of the ink mist I _m , which represents the increase or decrease in the ink mist I _m during continuous printing, can be used.

Furthermore, the total volume, maximum value, standard deviation, etc. of the ink mist _Im adhering to the nozzle surface 46 across multiple print jobs can be used as the jetting condition determination index. Furthermore, any combination of these can be used as the jetting condition determination index.

Furthermore, it is also possible to combine the standard deviation σ _t of the amount of deflection of ejection, which is used as the jetting condition determination index in the first embodiment, with the amount of ink mist I _m adhering to the nozzle surface 46. For example, when combining multiple jetting condition determination indexes, a weight may be defined for each of the multiple jetting condition determination indexes, and the multiple jetting condition determination indexes may be multiplied by the weight and then added together.

A high-speed camera positioned on the movement path of the inkjet head 30 can be used to photograph the nozzle surface 46. Instead of moving the inkjet head 30, the high-speed camera may be moved relative to a fixedly positioned inkjet head 30.

The nozzle surface 46 described in the embodiment is an example of an ejection surface. The area to which the ink mist I _m adheres, the volume of the ink mist I _m adhered to the nozzle surface 46, and the gradient of the volume of the ink mist I _m described in the embodiment are examples of quantitative values of the ink mist.

[Jeting Condition Determination Method According to Fifth Embodiment]
In the jetting condition determination method according to the fifth embodiment, a drive waveform is dynamically generated by selectively combining a plurality of waveform elements. The jetting condition determination method according to the fifth embodiment is applied to the inkjet printing system 10 according to the first embodiment as a hardware configuration. A description of the hardware will be omitted here.

[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.

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 settings of the inkjet head. Examples of individual differences between inkjet heads include differences in the flow path resistance of the ink flow path and mechanical errors in the mechanical components of the inkjet head.

As mentioned above, if only one type of optimized drive waveform is maintained, it is difficult to adjust it to suit the ejection status of each inkjet head. This requires know-how every time the jetting conditions and ink are changed, and a relatively large amount of time is spent evaluating the jetting conditions, etc.

For example, in the multi-pulse drive waveform shown in Figure 14, which combines multiple waveform elements, the types of combinations of waveform elements are limited by the number of waveform elements. Adjustable parameters are also limited by the pulse width, amplitude, and slope. Furthermore, the pulse width and slope are limited by the resonance period of the inkjet head, which ensures efficient ink ejection.

Furthermore, when evaluating jetting conditions through repeated trial and error, there is a risk that optimal jetting conditions may not be found and that the jetting conditions may end up being optimized locally.

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

Specify the number of pulses to be combined and generate all multi-pulse drive waveforms with the specified number of waveform elements. Calculate and evaluate the jetting condition judgment index for each multi-pulse drive waveform, and determine the jetting conditions corresponding to the jetting condition judgment index with the best evaluation results.

For example, multiple multi-pulse drive waveforms are prepared, and 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.

Optimization of the multi-pulse drive waveform may be performed by applying a trained learning model. For example, a trained learning model may be generated by learning combinations of multiple multi-pulse drive waveforms and evaluation scores for each multi-pulse drive waveform as training data, and the trained learning model may be used to optimize the multi-pulse drive waveform.

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

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 enables efficient ink ejection.

Figure 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 Figure 18 is the time interval between waveform elements, in units of microseconds. This is labeled KEEP TIME [μs] in the figure. The vertical axis of the graph shown in Figure 18 is the velocity of the ink droplet, in units of meters per second. This is labeled ejection velocity V [m/s] in the figure.

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

From the ink droplet velocity for each time interval between multiple waveform elements, the graph shown in FIG. 18 can be created, and the time interval _tINT1 between waveform elements at which the ink droplet velocity reaches a maximum value 460 and the time interval _tINT2 between waveform elements at which the ink droplet velocity reaches a maximum value can be determined as the time interval _Tc between waveform elements.

The maximum value of ink droplet velocity can be derived using methods other than measurements using an actual device. For example, it may be determined in advance using simulations, etc. As with the optimization of the multi-pulse drive waveform, a trained learning model may also be applied to deriving the time interval between waveform elements.

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

[Operation and effect of the fifth embodiment]
According to the jetting condition determination method of the fifth embodiment, it is 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.

In addition, this will enable efficient and reliable development in terms of inkjet printing systems and inkjet heads.

Note that 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.

[Combination of the embodiments]
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.

[Example of application to a 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 can 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.

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

Each processing unit of the discharge control device executes various programs to perform each step included in the jetting condition determination method, the steps of which are shown in Figure 8.

[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.

The term printing includes concepts such as image recording, image formation, printing, drawing, and printing. The term device can include the concept of a system.

The term "image" is used as a comprehensive term that includes not only photographic images, but also designs, characters, symbols, line drawings, mosaic patterns, color-coded patterns, and various other patterns, as well as appropriate combinations of these. The term "image" can also include image signals and image data that represent an image.

The embodiments of the present invention described above may have their constituent elements modified, added, or deleted as appropriate, without departing from the spirit of the present invention. The present invention is not limited to the embodiments described above, and many modifications may be made by those with ordinary skill in the art within the technical spirit of the present invention. Furthermore, the embodiments, modifications, and applications may be implemented in appropriate combinations.

1 Film substrate 1A Printing surface 1B Substrate support surface 10 Inkjet printing system 12 Paper feeder 14 Precoat device 16 Jetting device 18 Drying device 20 Inspection device 22 Recovery device 24 Conveying device 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 substrate 46 Nozzle surface 46A Nozzle forming area 48 Nozzle plate 50 Ink supply chamber 52 Ink circulation chamber 54 Supply side individual flow path 56 Recovery side individual flow path 60 Ink supply path 62 Individual supply path 64 Pressure chamber 66 Nozzle communication path 68 Circulation individual flow path 70 Circulation common flow path 72 Piezoelectric element 74 Vibration plate 76 Flow path structure 78 Nozzle portion 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 Pre-coat control unit 106 Jetting control unit 108 Drying control unit 110 Inspection control unit 112 Scan control unit 120 Image data processing unit 122 Scan data analysis unit 124 Discharge detection unit 126 Jetting condition setting unit 130 Memory 130A Jetting condition storage unit 132 Sensor 140 Scan data acquisition unit 142 Index calculation unit 144 Jetting condition acquisition unit 146 Jetting condition determination unit 148 Jetting condition output unit 200 Control device 202 Processor 204 Computer readable medium 206 Communication interface 208 Input/output interface 210 Bus 214 Input device 216 Display device 220 Transport control program 222 Pre-coat 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 Printing medium 302 Leading edge region 304 Test pattern image 304A First test pattern image 304B Second test pattern image 304C Third test pattern image 305 Trailing edge region 306 Printed image 308 Leading edge 309 Trailing edge 310 Pattern element 310A Pattern element 312 Circle 400 Multi-pulse driving waveform 402 First waveform element 404 Second waveform element 406 Third waveform element 408 Fourth waveform element 410 Fifth waveform element 440 Captured image 442 Trimmed image 444 Binarized image 446 White area 460 First maximum value 462 Second maximum value Steps from step S10 to step S20 Steps of jetting condition determination method

Claims (26)

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 ; 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 . 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. An ejection control device according to any one of claims 1 to 12, wherein the one or more processors determine second printing conditions to replace the first printing conditions based on the evaluation results of the first printing conditions. 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. 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. The discharge control device described in any one of claims 13 to 15, wherein the one or more processors compare the printing condition determination index derived by applying the first printing condition with the printing condition determination index derived by applying the second printing condition, and determine the printing condition corresponding to the better printing condition determination index as the printing condition to be applied to the continuous printing. 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. 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; 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; 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. The computer
acquiring first printing conditions including one or more printing parameters for printing to which the inkjet head is applied , 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 a plurality of printing conditions included in the first printing conditions using the printing condition determination index for each of the printing conditions . The computer
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. The computer
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. 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; On the computer,
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; On the computer,
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.