Discharge quantity upper limit determination method and printing device

Abstract

To provide a technique that can determine a discharge quantity upper limit, taking other standpoint of image quality into consideration as much as possible, while achieving desired color development.SOLUTION: A test pattern, which includes a plurality of patches having different discharge quantities per unit area with respect to liquid that is discharged from a printing head to a medium, is formed on the medium. A discharge quantity reference value which acts as a benchmark for an allowable range for an upper limit of the discharge quantities is obtained. A discharge quantity minimum value that is a minimum value in the allowable range and a discharge quantity maximum value that is a maximum value in the allowable range are determined based on the discharge quantity reference value. Read results of at least some of the plurality of patches are obtained. A provisional discharge quantity upper limit that is a provisional value of the upper limit is determined based on the read results. The upper limit is determined so that the value is equal to or larger than the discharge quantity minimum value and equal to or smaller than the discharge quantity maximum value, on the basis of the discharge quantity minimum value, the discharge quantity maximum value and the provisional discharge quantity upper limit.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a technique for determining an upper limit of the amount of liquid ejected per unit area from a print head onto a medium. [Background technology]

[0002] As a printing device, an inkjet printer that ejects ink droplets from multiple nozzles of a print head onto a printing medium is known. When the amount of ink ejected per unit area onto a printing medium is large, for example, phenomena such as "color saturation," "overflow," "bleeding," and "aggregation" may occur. Here, "color saturation" is a phenomenon in which the coloring remains almost unchanged even if the amount of ink ejected increases, and "overflow" is a phenomenon in which the periphery becomes darker than the center during the ink drying process. "Bleeding" is a phenomenon in which ink seeps out to the periphery, and "aggregation" is a phenomenon in which the dispersibility of ink dots decreases. The degree of these phenomena may vary depending on the type of printing medium and the type of ink. Therefore, an ink ejection amount upper limit value that indicates the upper limit of the ink ejection amount that can suppress these phenomena is set, and is used to create a color conversion LUT (lookup table). The printing device disclosed in Patent Document 1 performs a process to determine the above-mentioned ink ejection amount upper limit value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-126993 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the upper limit of the ink ejection amount is set so as to prevent "overflow," "bleeding," or "coagulation," the color development of the printed image may be insufficient. [Means for solving the problem]

[0005] The method for determining an upper limit of a discharge rate of a liquid discharged from a print head onto a medium is a method for determining an upper limit of a discharge rate per unit area of ​​the liquid, the method comprising the steps of: a test pattern forming step of forming a test pattern including a plurality of patches having different ejection amounts on the medium; an allowable range determination step of acquiring a discharge amount reference value that is a reference for an allowable range of the upper limit value, and determining a minimum discharge amount value that is a minimum value of the allowable range and a maximum discharge amount value that is a maximum value of the allowable range based on the discharge amount reference value; a provisional determination step of acquiring a reading result of at least a part of the plurality of patches and determining a provisional ejection amount upper limit value, which is a provisional value of the upper limit value, based on the reading result; a first final determination step of determining the upper limit value based on the minimum discharge amount value, the maximum discharge amount value, and the provisional upper limit value, so that the upper limit value is equal to or greater than the minimum discharge amount value and equal to or less than the maximum discharge amount value; Including, It has an aspect.

[0006] The printing device of the present invention further comprises: A print head that ejects liquid onto a medium; a control unit that performs control to form a test pattern including a plurality of patches with different ejection amounts per unit area of ​​the liquid on the medium, and performs processing to determine an upper limit value of the ejection amount; A reading unit that reads at least a part of the plurality of patches, The control unit is a first process of acquiring a discharge amount reference value that is a reference for an allowable range of the upper limit value, and determining a minimum discharge amount value that is a minimum value of the allowable range and a maximum discharge amount value that is a maximum value of the allowable range based on the discharge amount reference value; a second process of acquiring a reading result of at least a part of the plurality of patches from the reading unit, and determining a provisional ejection amount upper limit value, which is a provisional value of the upper limit value, based on the reading result; a third process of determining the upper limit value based on the minimum discharge amount value, the maximum discharge amount value, and the provisional upper limit value so that the upper limit value is equal to or greater than the minimum discharge amount value and equal to or less than the maximum discharge amount value; It has an aspect. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram illustrating a schematic configuration example of a printing apparatus. [Diagram 2] FIG. 4 is a diagram illustrating an example of the operation of the printer. [Diagram 3] FIG. 10 is a diagram illustrating an example of a test pattern on a medium. [Figure 4] FIG. 4 is a diagram showing an example of ink ejection amount. [Diagram 5] 11A and 11B are diagrams illustrating an example of bleeding that occurs in a patch having a line region. [Figure 6] 1A and 1B are diagrams illustrating examples of ink overflow. [Figure 7] 1A to 1C are diagrams illustrating examples of ink aggregation. [Figure 8] FIG. 4 is a diagram illustrating an example of the structure of color measurement information. [Figure 9] FIG. 13 is a diagram showing an example of determining the permissible range (Dt_min to Dt_max) of the discharge amount from the reference value Dt_goal of the discharge amount. [Figure 10] FIG. 4 is a diagram showing a schematic example of the correspondence relationship between the ink ejection amount and the color measurement value. [Figure 11] 10 is a flowchart showing an example of an ink ejection amount upper limit value determination process. [Figure 12] FIG. 4 is a diagram illustrating a display example of a UI screen. [Figure 13] 6 is a flowchart illustrating an example of a printing process. [Figure 14] 10 is a flowchart showing a schematic diagram of another example of the ink ejection amount upper limit value determination process. [Figure 15] 10 is a flowchart showing a schematic diagram of another example of the ink ejection amount upper limit value determination process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments of the present invention will be described. Of course, the following embodiments are merely illustrative of the present invention, and not all of the features shown in the embodiments are necessarily essential to the solution of the invention.

[0009] (1) Overview of the technology included in this invention: First, the outline of the technology included in the present invention will be described with reference to the examples shown in Figures 1 to 15. The figures in this application are diagrams showing examples in a schematic manner, and the magnification in each direction shown in these figures may differ, and the figures may not be consistent with each other. Of course, each element of the present technology is not limited to the specific example indicated by the symbol. In the "outline of the technology included in the present invention," the words in parentheses mean supplementary explanations of the immediately preceding words. In addition, in the present application, a numerical range "Min to Max" means equal to or greater than the minimum value Min and equal to or less than the maximum value Max.

[0010] [Aspect 1] A method for determining an upper limit value of an ejection volume according to one embodiment of the present technology is a method for determining an upper limit value Dt_final of an ejection volume per unit area for a liquid (e.g., ink 236) ejected from a print head 230 onto a medium ME0, as illustrated in Figures 1, 11, etc., and includes the following steps. (a1) A test pattern forming process ST1 for forming a test pattern 500 including a plurality of patches with different ejection amounts on the medium ME0. (a2) An acceptable range determination process ST2 in which a discharge volume reference value Dt_goal is obtained as the basis for the acceptable range of the upper limit value Dt_final, and a minimum discharge volume value Dt_min, which is the minimum value of the acceptable range, and a maximum discharge volume value Dt_max, which is the maximum value of the acceptable range, are determined based on the discharge volume reference value Dt_goal. (a3) A provisional determination step ST3 of acquiring a read result (eg, image information 333) of at least a part of the plurality of patches, and determining a provisional ejection amount upper limit value Dt_auto, which is a provisional value of the upper limit value Dt_final, based on the read result (333). (a4) A first final determination process ST4 for determining the upper limit value Dt_final based on the minimum discharge rate value Dt_min, the maximum discharge rate value Dt_max, and the provisional upper limit value Dt_auto so that the upper limit value Dt_final is greater than or equal to the minimum discharge rate value Dt_min and less than or equal to the maximum discharge rate value Dt_max.

[0011] In the above aspect, a discharge amount reference value Dt_goal is acquired as a reference for the allowable range of the upper limit value Dt_final of the liquid discharge amount, and the allowable range (Dt_min to Dt_max) is determined based on the discharge amount reference value Dt_goal. Also, a reading result (333) of at least a portion of the multiple patches is acquired, and a provisional discharge amount upper limit value Dt_auto is determined based on the reading result (333). Finally, a discharge amount upper limit value Dt_final is determined so as to be within the allowable range based on the minimum discharge amount value Dt_min, the maximum discharge amount value Dt_max, and the provisional discharge amount upper limit value Dt_auto. As described above, the above aspect can provide a method for determining the upper discharge amount limit that can determine the upper discharge amount limit while taking into account other image quality aspects as much as possible while obtaining the desired coloring. As a result, for example, when switching a printer to a new model, the coloring of the new model can be adjusted to be approximately the same as that of the old model by adjusting the discharge amount reference value Dt_goal to the ink discharge amount limit value Dt_final of the old model or its vicinity. At that time, the image quality aspects of "overflow", "bleeding" and "aggregation" are taken into account in the newly determined ink discharge amount limit value Dt_final.

[0012] Here, the ejection amount reference value may be acquired by accepting an operation to input the ejection amount reference value, or may be calculated based on the color measurement results of a plurality of color measurement patches having different liquid ejection amounts. The patch reading results include the patch imaging results by an imaging unit such as a camera, the patch reading results by an image reading unit such as a scanner, and the like. In this application, the terms "first", "second", . . . are terms for distinguishing between components among a plurality of components having similarities, and do not imply an order. Of course, the above remarks also apply to the following aspects.

[0013] [Aspect 2] 1, 11, etc., the allowable range determination step ST2 may acquire a color measurement result (334) of at least a part of the patches (e.g., color measurement information 334) that is different from the reading result (333). In the allowable range determination step ST2, the minimum discharge amount Dt_min and the maximum discharge amount Dt_max may be determined based on the color measurement result (334) and the discharge amount reference value Dt_goal, as illustrated in Figs. 9, 10, etc. Since the color measurement result (334) used to determine the tolerance range for obtaining the desired color indicates the color, the above embodiment can provide a suitable example for determining the upper discharge amount value that obtains the desired color while taking into account other image quality aspects as much as possible.

[0014] Here, the patch for obtaining the color measurement result may be different from the patch for obtaining the reading result, or may be the same as the patch for obtaining the reading result. This remark is also applied to the following aspects.

[0015] [Aspect 3] 9, 10, and 12, the allowable range determination step ST2 may accept an input of an allowable value (e.g., a threshold value ΔEa) of the color difference ΔE based on a reference colorimetric value (e.g., a reference colorimetric value Lab_goal) corresponding to the discharge amount reference value Dt_goal. In the allowable range determination step ST2, the minimum discharge amount Dt_min corresponding to the lower limit of the allowable value (ΔEa) and the maximum discharge amount Dt_max corresponding to the upper limit of the allowable value (ΔEa) based on the reference colorimetric value (Lab_goal) may be determined based on the colorimetric result (334) that differs depending on the discharge amount. The above aspect can provide a more suitable example for determining the upper limit of the ejection amount while obtaining a desired color and taking into account other aspects of image quality as much as possible.

[0016] [Aspect 4] In the first final determination step ST4, if the provisional discharge amount upper limit value Dt_auto is greater than the minimum discharge amount value Dt_min and less than the maximum discharge amount value Dt_max, the upper limit value Dt_final may be determined to be the provisional discharge amount upper limit value Dt_auto. In the first final determination step ST4, if the provisional discharge amount upper limit value Dt_auto is equal to or less than the minimum discharge amount value Dt_min, the upper limit value Dt_final may be determined to be the minimum discharge amount value Dt_min. In the first final determination step ST4, if the provisional discharge amount upper limit value Dt_auto is equal to or more than the maximum discharge amount value Dt_max, the upper limit value Dt_final may be determined to be the maximum discharge amount value Dt_max. The above aspect can provide a suitable example for determining the upper limit of the ejection amount while obtaining a desired color and taking into account other aspects of image quality as much as possible.

[0017] [Aspect 5] As illustrated in FIGS. 11 and 14, in the allowable range determination step ST2, when the processing setting is the first setting which means the use of the discharge amount reference value Dt_goal, the discharge amount minimum value Dt_min and the discharge amount maximum value Dt_max may be determined based on the discharge amount reference value Dt_goal. In the tentative determination step ST3, when the processing setting is the first setting, the provisional discharge amount upper limit value Dt_auto may be determined based on the reading result (333). In the first final determination step ST4, when the processing setting is the first setting, the upper limit value Dt_final may be determined so as to be equal to or greater than the discharge amount minimum value Dt_min and equal to or less than the discharge amount maximum value Dt_max based on the discharge amount minimum value Dt_min, the discharge amount maximum value Dt_max, and the provisional discharge amount upper limit value Dt_auto. This discharge amount upper limit value determination method may further include the following steps. (a5) when the processing setting is a second setting which means that the discharge volume reference value Dt_goal is not used, a second final determination process ST5 is performed in which a color measurement result (334) of at least a portion of the multiple patches is obtained, the color measurement result (334) being different from the reading result (333), a first provisional discharge volume upper limit value (e.g., an upper limit value Dt_4 at which color saturation does not occur) which is a provisional value of the upper limit value from the perspective of the color measurement result (334) is determined based on the color measurement result (334), the reading result (333) of at least a portion of the multiple patches is obtained, a second provisional discharge volume upper limit value (e.g., an upper limit value Dt_1 to Dt_3 at which color saturation does not occur) which is a provisional value of the upper limit value from the perspective of the reading result (333) is determined based on the reading result (333), and the upper limit value Dt_final is determined based on at least one of the first provisional discharge volume upper limit value (Dt_4) and the second provisional discharge volume upper limit values ​​(Dt_1 to Dt_3).

[0018] When the process setting is a first setting which means the use of the discharge amount reference value Dt_goal, the allowable range is determined based on the discharge amount reference value Dt_goal, the provisional discharge amount upper limit value Dt_auto is determined based on at least a portion of the read results (333) of the multiple patches, and the discharge amount upper limit value Dt_final is determined so as to be within the allowable range. When the process setting is a second setting which means the non-use of the discharge amount reference value Dt_goal, the first provisional discharge amount upper limit value (Dt_4) is determined based on at least a portion of the color measurement results (334) of the multiple patches, the second provisional discharge amount upper limit values ​​(Dt_1 to Dt_3) are determined based on at least a portion of the read results (333) of the multiple patches, and the discharge amount upper limit value Dt_final is determined based on at least one of the first provisional discharge amount upper limit value (Dt_4) and the second provisional discharge amount upper limit values ​​(Dt_1 to Dt_3). Therefore, the above aspect makes it possible to select whether or not to determine the upper limit value of the ejection amount while taking into account other aspects of image quality as much as possible while obtaining the desired color development, thereby improving convenience.

[0019] [Aspect 6] 11 and 15, in the tentative determination step ST3, when a difference value Dt_max-Dt_min obtained by subtracting the minimum discharge amount Dt_min from the maximum discharge amount Dt_max is greater than a predetermined value ΔDt, the provisional discharge amount upper limit value Dt_auto may be determined based on the reading result (333). In the first final determination step ST4, when the difference value Dt_max-Dt_min is greater than the predetermined value ΔDt, the upper limit value Dt_final may be determined based on the minimum discharge amount Dt_min, the maximum discharge amount Dt_max, and the provisional discharge amount upper limit value Dt_auto so as to be equal to or greater than the minimum discharge amount Dt_min and equal to or less than the maximum discharge amount Dt_max. This discharge amount upper limit value determination method may further include the following steps. (a6) A third final determination process ST6 for determining the upper limit value Dt_final so that it is greater than or equal to the minimum discharge volume Dt_min and less than or equal to the maximum discharge volume Dt_max, based on at least one of the discharge volume reference value Dt_goal, the minimum discharge volume Dt_min, and the maximum discharge volume Dt_max, when the difference value Dt_max-Dt_min is less than or equal to the predetermined value ΔDt.

[0020] When the difference between the maximum discharge amount Dt_max and the minimum discharge amount Dt_min is large, the provisional discharge amount upper limit Dt_auto is determined based on at least a part of the reading results (333) of the multiple patches, and the discharge amount upper limit Dt_final is determined so as to be within the allowable range. When the difference between the maximum discharge amount Dt_max and the minimum discharge amount Dt_min is small, the discharge amount upper limit Dt_final is determined so as to be within the allowable range based on at least one of the discharge amount reference value Dt_goal, the minimum discharge amount Dt_min, and the maximum discharge amount Dt_max. Therefore, the above aspect can shorten the calculation time for determining the discharge amount upper limit Dt_final when the difference between the maximum discharge amount Dt_max and the minimum discharge amount Dt_min is small.

[0021] [Aspect 7] As illustrated in FIG. 1, a printing device according to an aspect of the present technology includes a print head 230, a control unit 110, and a reading unit (e.g., an imaging unit 261). The print head 230 ejects a liquid (236) onto a medium ME0. The control unit 110 controls the formation of a test pattern 500 including a plurality of patches having different ejection amounts per unit area of ​​the liquid (236) onto the medium ME0, and performs processing to determine an upper limit value Dt_final of the ejection amount. The reading unit (261) reads at least a portion of the plurality of patches. The control unit 110 performs the following processing, as illustrated in FIG. 11, etc. (b1) A first process (e.g., steps S102, S106 to S108) of obtaining a discharge volume reference value Dt_goal that serves as the basis for the tolerance range of the upper limit value Dt_final, and determining a minimum discharge volume value Dt_min, which is the minimum value of the tolerance range, and a maximum discharge volume value Dt_max, which is the maximum value of the tolerance range, based on the discharge volume reference value Dt_goal. (b2) A second process (e.g., steps S106, S110 to S116) of obtaining reading results (333) of at least a portion of the multiple patches from the reading unit (261) and determining a provisional discharge volume upper limit value Dt_auto, which is a provisional value of the upper limit value Dt_final, based on the reading results (333). (b3) A third process (e.g., step S118) for determining the upper limit value Dt_final based on the minimum discharge rate value Dt_min, the maximum discharge rate value Dt_max, and the provisional upper limit value Dt_auto so that the upper limit value Dt_final is greater than or equal to the minimum discharge rate value Dt_min and less than or equal to the maximum discharge rate value Dt_max.

[0022] The above aspect can provide a printing apparatus capable of determining an upper limit value for the ejection amount while obtaining a desired color and taking into account other aspects of image quality as much as possible. Here, the reading unit includes an imaging unit such as a camera, an image reading unit such as a scanner, and the like. The control unit may perform the processes corresponding to the above-mentioned aspects 2 to 6.

[0023] Furthermore, the present technology is applicable to a printing method including the above-mentioned method for determining an upper limit of the discharge amount, a multifunction device including the above-mentioned printing device, a program for determining an upper limit of the discharge amount for realizing the above-mentioned method for determining an upper limit of the discharge amount in a computer, a print control program for realizing the above-mentioned printing method in a computer, a computer-readable recording medium having any of the above-mentioned programs recorded thereon, etc. Any of the above-mentioned devices may be composed of multiple distributed parts.

[0024] (2)Specific examples of printing device configuration: Fig. 1 is a schematic diagram of a configuration of a printing device. Fig. 2 is a schematic diagram of an operation of a printer. Fig. 3 is a schematic diagram of a test pattern on a medium. The printing device 1 shown in FIG. 1 is a device in a broad sense including a host device 100 and a printer 200, and can also be called a printing system. Of course, the printing device 1 may be the printer 200 alone. The host device 100 includes a CPU (Central Processing Unit) 111, which is a processor, a ROM (Read Only Memory) 112, a RAM (Random Access Memory) 113, a storage device 114, an input device 115, a display device 116, a communication I / F (interface) 117, and the like. The above-mentioned elements (111 to 117) are electrically connected and are capable of inputting and outputting information to and from each other. The ROM 112, the RAM 113, and the storage device 114 are memories, and at least the ROM 112 and the RAM 113 are semiconductor memories. The configuration of the printer 200 will be described later.

[0025] The storage device 114 stores an OS (operating system) (not shown), a print control program PR0, solid pattern data 331, lined pattern data 332, and the like. The solid pattern data 331 is used to print the solid pattern arrays P21 to P25 included in the test pattern 500 shown in FIG. 3. The lined pattern data 332 is used to print the line pattern arrays P11 to P16 included in the test pattern 500 shown in FIG. 3. Furthermore, the storage device 114 also stores imaging information 333 generated by the imaging unit 261 of the printer 200, colorimetric information 334 generated by the colorimetric unit 262 of the printer 200, and the like. The storage device 114 may be a nonvolatile semiconductor memory such as a flash memory, a magnetic storage device such as a hard disk, or the like. The input device 115 may be a pointing device, a hard key including a keyboard, a touch panel attached to the surface of a display panel, or the like. The display device 116 displays a screen corresponding to the display information based on the display information. The display device 116 may be a liquid crystal display panel, or the like. The communication I / F 117 is connected to a communication I / F 220 of the printer 200, and inputs and outputs information such as print data to and from the printer 200. Communication between the communication I / Fs 117 and 220 may be wired or wireless, or may be network communication such as a local area network (LAN) or the Internet.

[0026] The print control program PR0 causes the host device 100 to function as an overflow upper limit calculation unit 311, a bleeding upper limit calculation unit 312, an aggregation upper limit calculation unit 313, a color saturation upper limit calculation unit 314, a discharge amount upper limit determination unit 315, and the like. Details of these elements (311 to 315) will be described later. The print control program PR0 causes the host device 100 to realize an overflow upper limit calculation function FU1 corresponding to the overflow upper limit calculation unit 311, a bleeding upper limit calculation function FU2 corresponding to the bleeding upper limit calculation unit 312, an aggregation upper limit calculation function FU3 corresponding to the aggregation upper limit calculation unit 313, a color saturation upper limit calculation function FU4 corresponding to the color saturation upper limit calculation unit 314, a discharge amount upper limit determination function FU5 corresponding to the discharge amount upper limit determination unit 315, and the like. The discharge amount upper limit can be called a discharge amount limit value, and more specifically, can be called an ink duty limit value. The CPU 111 of the host device 100 reads information stored in the storage device 114 into the RAM 113 as appropriate, and executes the read program to perform various processes. The CPU 111 performs processes corresponding to the above-mentioned functions (FU1 to FU5) by executing the print control program PR0 read into the RAM 113. The CPU 111 that executes the print control program PR0 is an example of the control unit 110, and performs the steps corresponding to the above-mentioned functions (FU1 to FU5). The computer-readable recording medium that stores the print control program PR0 is not limited to a storage device inside the host device, and may be a recording medium external to the host device.

[0027] The host device 100 includes computers such as personal computers, mobile phones such as smartphones, digital cameras, digital video cameras, etc. The host device 100 may have all of its components (111-117) in one housing, or may be composed of multiple devices separated so as to be able to communicate with each other. The present technology can also be implemented if at least a part of the printer 200 is in the host device 100.

[0028] 1 and 2 is an inkjet printer that ejects C ink, M ink, Y ink, and K ink as ink 236 containing coloring material from a print head 230 onto a medium ME0 to form a print image IM0 corresponding to print data. Here, the ink 236 is an example of a liquid, and ink droplets 237 ejected from the print head 230 are an example of droplets, with C representing cyan, M representing magenta, Y representing yellow, and K representing black. The printer 200 includes a controller 210, the above-mentioned communication I / F 220, the print head 230, a drive unit 250, an imaging unit 261, a color measurement unit 262, and the like. The imaging unit 261 is an example of a reading unit that reads at least a portion of a plurality of patches included in the test pattern 500. The controller 210 includes a processor CPU 211, a ROM 212, a RAM 213, a color conversion unit, a halftone processing unit, a drive signal transmission unit, etc., and controls the operation of the communication I / F 220, the print head 230, the drive unit 250, the image capture unit 261, the color measurement unit 262, etc. Based on print data acquired from the host device 100, the controller 210 controls the ejection of ink droplets 237 by the print head 230 and the scanning by the drive unit 250. For example, when two colors, R, G, and B, are assigned to each pixel, the controller 210 controls the ejection of ink droplets 237 by the print head 230 and the scanning by the drive unit 250. 8 It is assumed that the communication I / F 220 receives print data including RGB data having integer values ​​equal to or greater than the gradation. Here, R means red, G means green, and B means blue. The color conversion unit converts the RGB data into two colors, C, M, Y, and K, for each pixel. 8 The controller 210 can be configured with a SoC (System on a Chip) or the like.

[0029] The printer 200 shown in FIG. 2 is a serial printer that performs printing while moving a carriage 252 in both directions along a first direction D1. Of course, the printer 200 may be a line printer that does not have a carriage. The carriage 252 is equipped with a print head 230, an imaging unit 261, and a color measurement unit 262. The drive unit 250 includes a carriage drive unit 251 that moves the carriage 252 in the forward direction D11 and the backward direction D12 under the control of the controller 210, and a feed unit 255 that feeds the medium ME0 in the second direction D2 under the control of the controller 210. Here, the forward direction D11 and the backward direction D12 are directions along the first direction D1, the backward direction D12 is a direction opposite to the forward direction D11, and the second direction D2 is a direction perpendicular to the first direction D1.

[0030] The print head 230 includes a drive circuit, a drive element, and the like, and performs printing by ejecting ink droplets 237 from a plurality of nozzles 234 included in a nozzle row 233 onto the medium ME0. Here, the nozzle means a small hole from which ink droplets are ejected, and the nozzle row means an arrangement of a plurality of nozzles. The drive element may be a piezoelectric element that applies pressure to ink in a pressure chamber that communicates with the nozzle 234, or a drive element that uses heat to generate air bubbles in the pressure chamber to eject ink droplets 237 from the nozzle 234. The drive signal transmission unit included in the controller 210 generates a drive signal based on the print data, for example, a drive signal according to dot data, and outputs the drive signal to the drive circuit of the print head 230. The drive signal corresponds to a voltage signal applied to the drive element of the print head 230. For example, if the binary dot data based on the print data is "dot formation", the drive signal transmission unit outputs a drive signal that ejects ink droplets for dot formation. In addition, when the dot data is four-value data, the drive signal transmission unit outputs a drive signal to eject ink droplets for large dots if the dot data is "large dot formation", outputs a drive signal to eject ink droplets for medium dots if the dot data is "medium dot formation", and outputs a drive signal to eject ink droplets for small dots if the dot data is "small dot formation".

[0031] The print head 230 shown in FIG. 2 has a plurality of nozzle rows 233 including a plurality of nozzles 234 arranged at intervals of a predetermined nozzle pitch in the second direction D2, and is arranged on a surface of the carriage 252 facing the medium ME0. The arrangement direction of the plurality of nozzles 234 included in each nozzle row 233 may be shifted from the second direction D2 as long as it intersects with the first direction D1. The plurality of nozzle rows 233 include a cyan nozzle row 23C that ejects C ink droplets 237, a magenta nozzle row 23M that ejects M ink droplets 237, a yellow nozzle row 23Y that ejects Y ink droplets 237, and a black nozzle row 23K that ejects K ink droplets 237. Each nozzle row 233 ejects ink droplets 237 toward the medium ME0. The plurality of nozzles 234 included in each nozzle row 233 may be arranged in a single row or in a staggered manner, i.e., in two rows. When the ink droplets 237 land on the medium ME0, dots DT0 (see FIG. 4) of ink 236 are formed on the medium ME0. As a result, a printed matter having a print image IM0 on the medium ME0 is obtained. The medium ME0 is not particularly limited, and includes paper, fabric, resin, metal, etc. The shape of the medium ME0 may be a roll, a cut two-dimensional shape, or a three-dimensional shape.

[0032] The imaging unit 261 includes an area sensor, captures an image of each patch included in the test pattern 500 shown in FIG. 3, for example, patches 511 to 515, and outputs imaging information 333, which is an imaging result as a reading result. It can be said that the imaging unit 261 of this specific example reads a part of the patches included in the test pattern 500, and the control unit 110 of this specific example obtains a reading result of a part of the patches included in the test pattern 500. The reading result is different from the color measurement result by the colorimetric unit 262. Note that the imaging unit 261 may include a line sensor instead of an area sensor. The imaging unit 261 is disposed on a surface of the carriage 252 facing the medium ME0, and captures an image when the carriage 252 moves along the first direction D1. The imaging unit 261 shown in FIG. 2 is located in a position facing the second direction D2 from the print head 230 in the carriage 252. This allows the imaging unit 261 to capture an image of a patch formed in a certain main scan in a subsequent main scan. The printer 200 transmits imaging information 333 generated by the imaging unit 261 to the host device 100. The host device 100 may store the received imaging information 333 as is in the storage device 114, or may store updated imaging information 333 to which additional information obtained from the received imaging information 333 has been added in the storage device 114.

[0033] The colorimetric unit 262 measures the color of individual patches included in the test pattern 500 shown in FIG. 3, for example, patches 521 to 525, and outputs colorimetric information 334 as the colorimetric result corresponding to the color of the patch. It can be said that the colorimetric unit 262 of this specific example measures the color of some of the patches included in the test pattern 500, and the control unit 110 of this specific example obtains the colorimetric result of some of the patches included in the test pattern 500. The colorimetric result is different from the imaging result by the imaging unit 261. The colorimetric information 334 is, for example, CIE (International Commission on Illumination) L * a * b * Lightness in color space L * and chromaticity coordinate a * ,b * The color value is expressed as follows. *" is omitted. Of course, the colorimetric information 334 may be color values ​​in the CIE XYZ color space or the like. The colorimetric unit 262 is disposed on the surface of the carriage 252 facing the medium ME0, and performs colorimetric measurement when the carriage 252 moves along the first direction D1. The colorimetric unit 262 shown in FIG. 2 is located on the carriage 252 facing the print head 230 in the second direction D2. This allows the colorimetric unit 262 to measure the color of a patch formed in a certain main scan in a subsequent main scan. The printer 200 transmits the colorimetric information 334 generated by the colorimetric unit 262 to the host device 100. The host device 100 may store the received colorimetric information 334 as is in the storage device 114, or may store updated colorimetric information 334 to which additional information obtained from the received colorimetric information 334 has been added in the storage device 114.

[0034] As shown in Fig. 3, the test pattern 500 includes a line pattern sequence P11-P16 and a solid pattern sequence P21-P25. In the example shown in Fig. 3, the pattern sequences (P11-16, P21-25) are arranged in a first direction D1, and a plurality of patches included in each pattern sequence (P11-16, P21-25), for example, patches 511-515, are arranged in a second direction D2. Of course, the arrangement direction of the pattern sequences and the arrangement direction of the patches in the pattern sequences are not limited to the example shown in Fig. 3, and for example, the pattern sequences may be arranged in the second direction D2, and the patches in the pattern sequences may be arranged in the first direction D1. First, the configuration of the solid pattern arrays P21 to P25 will be described. The solid pattern arrays P21 to P25 can be used to determine the upper limit of the ink ejection amount at which the color saturation of the ink 236 does not occur.

[0035] FIG. 4 is a diagram for explaining a schematic example of an ink discharge amount (referred to as Duty). In the example shown in FIG. 4, 6×6=36 pixels PX0 are shown as the predetermined number of pixels PX0 corresponding to a unit area. Of course, the predetermined number corresponding to a unit area is not limited to 36, and a larger area may be treated as the unit area. The left side of FIG. 4 shows an example in which ink droplets 237 are not discharged to the predetermined number of pixels PX0 corresponding to the unit area. The right side of FIG. 4 shows an example in which dots DT0 of ink of a primary color are formed on all pixels PX0 corresponding to the unit area. Pixels PX0 are the smallest elements constituting an image to which a color can be independently assigned. A primary color is a color that is expressed by only one type of ink. The ink discharge amount means the total amount of ink discharged per unit area. In other words, the ink discharge amount Duty means the ratio (including percentage) of the number of ink droplets 237 discharged to a predetermined number of pixels PX0, and means the ratio when converted to the largest ink droplet when ink droplets 237 of different sizes are discharged to the pixel PX0. For example, when Nd ink droplets 237 are discharged to 100 pixels, the ink discharge amount Duty is Nd%. When no ink droplets 237 are discharged to a predetermined number of pixels PX0 as shown on the left side of FIG. 4, Duty=0%, and when ink droplets 237 of the primary color are discharged to all pixels PX0 as shown on the right side of FIG. 4, Duty=100%. Note that when a mixed color image such as a secondary color is formed, multiple types of ink droplets 237 are discharged to one pixel PX0, so Duty may be greater than 100%. For example, the ink discharge amount Duty of the secondary color is a maximum of 200%. A secondary color is a color that is produced using two different inks of different colors.

[0036] "Ink color saturation" refers to the phenomenon in which the color development hardly changes with the amount of ink ejected, in other words, the color development hardly changes even if the amount of ink ejected increases. "Color development" refers to the darkness of a printed image such as a patch, and is calculated by subtracting the lightness L of the Lab color space from 100 (100-L), and the saturation (a) obtained from the chromaticity coordinates a and b. 2 +b 2 ) 1 / 2, etc. Each of the solid pattern strings P21 to P25 shown in FIG. 3 includes a plurality of patches whose ink ejection amount changes stepwise, for example, rectangular patches 521 to 525. In the solid pattern string P25, the ink ejection amount decreases in the order of patches 521, 522, 523, 524, and 525. The remaining solid pattern strings P21 to P24 also have a smaller ink ejection amount as the patch goes down. The solid pattern string P21 includes a plurality of patches whose C ink ejection amount decreases stepwise from 100%. The solid pattern string P22 includes a plurality of patches whose M ink ejection amount decreases stepwise from 100%. The solid pattern string P23 includes a plurality of patches whose Y ink ejection amount decreases stepwise from 100%. The solid pattern string P24 includes a plurality of patches whose K ink ejection amount decreases stepwise from 100%. In the primary color solid pattern arrays P21 to P24, the intervals between the ink ejection amounts of the patches are not particularly limited and may be 5% intervals, 10% intervals, etc. The solid pattern array P25 includes multiple patches in which the combined ejection amount of C ink and M ink decreases stepwise from 200%. In the secondary color solid pattern array P25, the intervals between the ink ejection amounts of the patches are not particularly limited and may be 10% intervals, 20% intervals, etc. Of course, the solid pattern array is not limited to the example shown in Fig. 3. For example, the test pattern 500 may include a solid pattern array of a tertiary color formed with C ink, M ink, and Y ink, or may include a solid pattern array of a secondary color formed with C ink and Y ink.

[0037] The line pattern sequence P11 to P16 can be used to determine the "non-overflow upper limit", the "non-bleeding upper limit", and the "non-aggregation upper limit". The "non-overflow upper limit" refers to the upper limit of the ink discharge amount at which ink overflow does not occur. "Ink overflow" refers to a phenomenon in which ink discharged to a certain area of ​​the medium ME0 accumulates in the periphery of the area as the ink dries, making the periphery darker than the center of the area. The "non-bleeding upper limit" refers to the upper limit of the ink discharge amount at which ink bleeding does not occur. "Ink bleeding" refers to a phenomenon in which ink discharged to a certain area of ​​the medium ME0 is not absorbed by the medium ME0, and ink pools are formed at the outline of the area, causing shaky patterns. The "non-aggregation upper limit" refers to the upper limit of the ink discharge amount at which ink aggregation does not occur. "Ink aggregation" refers to a phenomenon in which the dispersibility of dots DT0 formed on the medium ME0 by ink droplets that land on the medium ME0 decreases. If the dispersibility of the dots DT0 decreases, the graininess of the area increases, and the image quality decreases. The line pattern arrays P11 to P16 have a configuration similar to the solid pattern arrays P21 to P25, except for the configuration of each patch.

[0038] Fig. 5 shows a schematic example of a patch having a line region. A patch 510 shown in Fig. 5 is representative of the patches 511 to 515 shown in Fig. 3. The structures of the patches 511 to 515 will be described with reference to the patch 510 shown in Fig. 5. The left side of Fig. 5 shows the patch 510 in which no ink bleeding has occurred. The right side of Fig. 5 shows the patch 510 in which ink bleeding has occurred. The ink bleeding will be described later.

[0039] The patch 510 includes two solid areas 531 and a line area 532 between these solid areas 531. Each solid area 531 is a rectangular solid image of a different color from the line area 532 and is in contact with the line area 532. In the patch 510 shown in FIG. 5, the solid areas 531 have the same color. The two solid areas 531 shown in FIG. 5 are separated into upper and lower parts, but may be separated into left and right parts, for example. The number of solid areas 531 included in each patch 510 may be three or more. The solid areas 531 are used to determine whether or not ink has overflowed and whether or not ink has aggregated. The line area 532 is a linear solid image of a different color from the solid areas 531 and is in contact with both solid areas 531. The line area 532 is used to determine whether or not ink has bleed.

[0040] 3 includes a plurality of patches, for example, rectangular patches 511-515, in which the ink ejection amount for the solid region 531 and the line region 532 changes stepwise. The line pattern sequence P11 includes a plurality of patches in which the ejection amount of K ink corresponding to the solid region 531 is gradually decreased from 100%, and the ejection amount of C ink corresponding to the line region 532 is gradually decreased from 100%. The line pattern sequence P12 includes a plurality of patches in which the ejection amount of Y ink corresponding to the solid region 531 is gradually decreased from 100%, and the ejection amount of C ink corresponding to the line region 532 is gradually decreased from 100%. The line pattern sequence P13 includes a plurality of patches in which the ejection amount of C ink corresponding to the solid region 531 is gradually decreased from 100%, and the ejection amount of M ink corresponding to the line region 532 is gradually decreased from 100%. The line pattern array P14 includes a plurality of patches in which the ejection amount of M ink corresponding to the solid region 531 is gradually decreased from 100%, and the ejection amount of Y ink corresponding to the line region 532 is gradually decreased from 100%. The line pattern array P15 includes a plurality of patches in which the ejection amount of Y ink corresponding to the solid region 531 is gradually decreased from 100%, and the ejection amount of K ink corresponding to the line region 532 is gradually decreased from 100%. The line pattern array P16 includes a plurality of patches in which the ejection amount of K ink corresponding to the solid region 531 is gradually decreased from 100%, and the ejection amount of C ink and M ink combined corresponding to the line region 532 is gradually decreased from 200%. When the solid region 531 and the line region 532 are primary colors, the interval between the ink ejection amounts of the patches is not particularly limited and may be 5% intervals, 10% intervals, etc. When the solid area 531 and the line area 532 are in a secondary color, the interval between the ink ejection amounts of the patches is not particularly limited, and may be 10% intervals, 20% intervals, or the like. Of course, the line pattern sequence is not limited to the example shown in Fig. 3. For example, the test pattern 500 may include a line pattern sequence in which the line region 532 is a tertiary color, or a line pattern sequence in which the solid region 531 is a secondary color.

[0041] FIG. 6 schematically illustrates ink overflow in the solid area 531. When ink overflow occurs in the solid area 531 on the medium ME0, in the solid area 531, the color of the peripheral portion 534 becomes darker than the color of the central portion 533 surrounded by the peripheral portion 534. When the peripheral portion 534 is darker than the central portion 533, the lightness L of the peripheral portion 534 is lower than that of the central portion 533, the RGB value of the peripheral portion 534 is smaller than that of the central portion 533, the CMYK value of the peripheral portion 534 is larger than that of the central portion 533, and when the solid area 531 is a chromatic color, the chroma of the peripheral portion 534 is higher than that of the central portion 533. The ink overflow is more likely to occur as the ink discharge amount increases.

[0042] When the imaging unit 261 shown in FIG. 1 images the solid area 531, the overflow upper limit value calculation unit 311 can obtain an overflow degree V1 (see FIG. 11), which is the difference between the detected density indicating the density of the peripheral portion 534 and the detected density indicating the density of the central portion 533, based on the imaging information 333. The overflow upper limit value calculation unit 311 compares the overflow degree V1 with an overflow determination threshold TH1 (see FIG. 11). For example, when V1≧TH1, it is determined that there is ink overflow, and when V1<TH1, it is determined that there is no ink overflow. The overflow upper limit value calculation unit 311 obtains, for each line pattern column P11 to P16, the maximum ink discharge amount at which V1<TH1 as an overflow non-occurrence upper limit value Dt_1 (see FIG. 11).

[0043] The overflow determination threshold TH1 (TH1>0) used to determine whether ink overflows can be determined in advance by a plurality of testers (people performing sensory evaluation) performing sensory evaluation of a plurality of test patterns printed on the medium ME0. For example, as shown in FIG. 6, a plurality of types of test patterns including a solid area 531 having a difference in detection density between a peripheral portion 534 and a central portion 533 are prepared corresponding to the difference in detection density, and printed on the medium ME0. The tester visually checks the plurality of types of test patterns printed on the medium ME0 and performs sensory evaluation by selecting a patch in which the difference in detection density is visually recognizable. The overflow determination threshold TH1 is determined by statistically analyzing the results of the same sensory evaluation performed by the plurality of testers. When the overflow determination threshold TH1 is finally determined from the analysis results, a histogram is created in which the difference in detection density is binned, and the difference in detection density of the peak frequency may be set as the overflow determination threshold TH1, or the weighted average value may be set as the overflow determination threshold TH1. The design specifications of the printing device 1 may be taken into account in the overflow determination threshold TH1. The presence or absence of ink overflow is determined according to the obtained overflow determination threshold TH1, thereby obtaining a result that matches human perception. The determined overflow determination threshold TH1 is stored in the storage device 114.

[0044] Fig. 5 shows a schematic example of bleeding that occurs in a patch 510. The left side of Fig. 5 shows a patch 510 formed on a medium ME1 that is resistant to ink bleeding. The right side of Fig. 5 shows a patch 510 formed on a medium ME2 that is resistant to ink bleeding. For example, glossy paper is an example of a medium ME1 that is resistant to ink bleeding, and plain paper and cloth are examples of a medium ME2 that is resistant to ink bleeding. In the contour portion of the line region 532 formed on the medium ME1 where ink hardly bleeds, rattling due to bleeding is not seen. In the contour portion of the line region 532 formed on the medium ME2 where ink easily bleeds, rattling due to bleeding is seen. In the medium ME2 where ink easily bleeds, the ink in the line region 532 bleeds into the surroundings, so the width w2 of the line region 532 formed on the medium ME2 is wider than the width w1 of the line region 532 formed on the medium ME1 where ink hardly bleeds. Therefore, the width of the line region 532 indicates the bleeding degree V2 (see FIG. 11), and it can be said that the greater the width of the line region 532, the greater the degree of bleeding. Ink bleeding is more likely to occur as the ink ejection amount increases.

[0045] When the imaging unit 261 shown in FIG. 1 images the patch 510, the bleeding upper limit value calculation unit 312 can acquire the width of the line region 532 as the bleeding degree V2 based on the imaging information 333. The bleeding upper limit value calculation unit 312 compares the bleeding degree V2 with the bleeding determination threshold TH2 (see FIG. 11). For example, when V2≧TH2, it is determined that there is ink bleeding, and when V2<TH2, it is determined that there is no ink bleeding. The bleeding upper limit value calculation unit 312 obtains, for each line pattern column P11 to P16, the maximum ink ejection amount at which V2<TH2 as the bleeding non-occurrence upper limit value Dt_2 (see FIG. 11).

[0046] The bleeding judgment threshold TH2 (TH2>0) used to judge the presence or absence of ink bleeding can be determined in advance by a plurality of testers performing sensory evaluation of a plurality of test patterns printed on the medium ME0. For example, a plurality of types of test patterns including a patch 510 as shown in FIG. 5 are prepared corresponding to the degree of the width of the line region 532, and printed on the medium ME0. The tester visually checks the plurality of types of test patterns printed on the medium ME0 and performs sensory evaluation such as selecting a patch in which the occurrence of ink bleeding can be visually recognized. The bleeding judgment threshold TH2 is determined by statistically analyzing the results of the same sensory evaluation performed by the plurality of testers. When the bleeding judgment threshold TH2 is finally determined from the analysis result, a histogram is created in which the width of the line region 532 is a bin, and the width of the peak frequency may be set as the bleeding judgment threshold TH2, or the weighted average value may be set as the bleeding judgment threshold TH2. The design specifications of the printing device 1 may be taken into account in the bleeding judgment threshold TH2. The presence or absence of ink bleeding is determined according to the obtained bleeding determination threshold value TH2, thereby obtaining a result that matches human perception. The determined bleeding determination threshold value TH2 is stored in the storage device 114.

[0047] Figure 7 shows a schematic example of ink aggregation in a solid area 531. The upper part of Figure 7 shows the pattern of dots DT0 at timing t1, the moment when an ink droplet 237 lands on the medium ME0. The lower part of Figure 7 shows the pattern of dots DT0 at timing t2, when multiple dots DT0 that are not fixed on the medium ME0 are attracted to each other and gather together. When the medium ME0 easily absorbs ink like plain paper or the like, as shown in the upper part of FIG. 7, the dots DT0 are fixed to the medium ME0 in the pattern at timing t1. Here, among the plurality of dots DT0, attention is paid to a certain dot DT1 and the dot DT2 closest to this dot DT1. When the medium ME0 hardly absorbs ink like a film or coated paper, as shown in the lower part of FIG. 7, a plurality of dots DT0 close to each other attract and gather, changing into one large dot, for example, dot DT3. This phenomenon is the aggregation of ink. Note that the dot DT3 shown in the lower part of FIG. 7 corresponds to the dot DT1 in the upper part of FIG. 7, and the dot DT4 shown in the lower part of FIG. 7 is at the position closest to the dot DT3. In the example shown in FIG. 7, it is shown that a plurality of dots including the dot DT2 centered on the dot DT1 have changed into a large dot DT3. As a result, the distance d2 between the dot DT3 and the dot DT4 becomes longer than the distance d1 between the dot DT1 and the dot DT2. The aggregation of ink is more likely to occur as the ink ejection amount increases.

[0048] When the imaging unit 261 shown in FIG. 1 images the solid area 531, the aggregation upper limit value calculation unit 313 can obtain at least one of the representative value of the dot size and the representative value of the distance between dots as the aggregation degree V3 (see FIG. 11) based on the imaging information 333. The representative value of the dot size may be the arithmetic mean value of the dot sizes or the peak value of the dot sizes, etc. The representative value of the distance between dots may be the arithmetic mean value of the distances between dots or the peak value of the distances between dots, etc. The aggregation degree V3 may be a representative value combining the dot size and the distance between dots. The aggregation upper limit value calculation unit 313 compares the aggregation degree V3 with the aggregation determination threshold TH3 (see FIG. 11), and for example, determines that there is ink aggregation when V3≧TH3, and determines that there is no ink aggregation when V3<TH3. The aggregation upper limit value calculation unit 313 obtains, for each line pattern column P11 to P16, the maximum ink ejection amount at which V3<TH3 as the aggregation non-occurrence upper limit value Dt_3 (see FIG. 11).

[0049] The aggregation judgment threshold TH3 (TH3>0) used to judge the presence or absence of ink aggregation can be determined in advance by a plurality of testers performing sensory evaluation of a plurality of test patterns printed on the medium ME0. For example, as shown in FIG. 7, a plurality of types of test patterns including a solid area 531 where ink aggregation occurs are prepared corresponding to the degree of ink aggregation, and printed on the medium ME0. The tester visually checks the plurality of types of test patterns printed on the medium ME0 and performs sensory evaluation such as selecting a patch where the occurrence of ink aggregation is visually recognized. The aggregation judgment threshold TH3 is determined by statistically analyzing the results of the same sensory evaluation performed by the plurality of testers. When the aggregation judgment threshold TH3 is finally determined from the analysis results, a histogram is created in which the aggregation degree V3 is a bin, and the aggregation degree V3 of the peak frequency may be set as the aggregation judgment threshold TH3, or the weighted average value may be set as the aggregation judgment threshold TH3. The design specifications of the printing device 1 may be taken into account in the aggregation judgment threshold TH3. The presence or absence of ink aggregation is determined in accordance with the obtained aggregation determination threshold TH3, thereby obtaining a result that matches human perception. The determined aggregation determination threshold TH3 is stored in the storage device 114.

[0050] When the final upper limit of the ejection amount is determined based on at least one of the upper limit of the overflow non-occurrence Dt_1, the upper limit of the bleeding non-occurrence Dt_2, and the upper limit of the aggregation non-occurrence Dt_3, the image quality of the printed image IM0 is expected to improve, but the color development of the printed image IM0 may be insufficient. This is because the final upper limit of the ejection amount may be smaller than the upper limit of the ink ejection amount at which the ink does not become saturated, and in this case the color development capability of the ink is not fully exhibited. Furthermore, when switching the printer 200 to a new model, there is a need to maintain the color development of the old model in the new model. In this specific example, the final upper limit value of the ejection amount is determined by taking into consideration the quality of ink overflow, bleeding, and coagulation related to the image quality of the printed image IM0 while maintaining the color development of the printed image IM0 at the same level as the old model. As illustrated in Figures 9 and 10, the host device 100 of this specific example determines the allowable ejection amount range (Dt_min to Dt_max) based on the ejection amount reference value Dt_goal based on the color development of the old model, and performs processing to determine the final upper limit value Dt_final within this allowable ejection amount range.

[0051] First, with reference to FIG. 8, an example of the structure of the colorimetric information 334 stored in the storage device 114 will be described. 8, "Color" indicates the color of the solid pattern rows P21 to P25 in FIG. 3, "Duty" indicates the ink ejection amount, "Lab" indicates the colorimetric value, "S" indicates a value representing color development, and "ΔS" indicates the change in color development value S between ink ejection amount duties. For example, in the solid pattern row P21 of C, the colorimetric value Lab of Duty=100% is indicated by "Lab_C100", and the color development value S of Duty=100% is indicated by "S_C100". In the solid pattern row P25 of C and M, the colorimetric value Lab of Duty=200% is indicated by "Lab_CM200", and the color development value S of Duty=200% is indicated by "S_CM200".

[0052] The host device 100 receives colorimetric information including the colorimetric values ​​Lab linked to the ink ejection amount duty for the solid pattern arrays P21 to P25 from the printer 200, and stores colorimetric information 334 including the colorimetric value S calculated from the colorimetric values ​​Lab as additional information in the storage device 114. The colorimetric value S may be (100-L) based on the lightness L included in the colorimetric values ​​Lab, or may be saturation based on the chromaticity coordinates a, b included in the colorimetric values ​​Lab. The color saturation of the ink can be represented by the change ΔS in the color development value S due to the change in the ink ejection amount Duty in each solid pattern column P21 to P25. For example, in the solid pattern column P21 of C, when the ink ejection amount Duty increases from 80% to 90%, the change ΔS_C80-90 in the color development value S is S_C90 - S_C80, and when the ink ejection amount Duty increases from 90% to 100%, the change ΔS_C90-100 in the color development value S is S_C100 - S_C90. The host device 100 can determine whether color saturation has occurred by applying a color saturation determination threshold value (denoted as TH4) to the change ΔS in the color development value S. For example, the host device 100 can determine that color saturation has occurred when ΔS ≧ TH4, and can determine that color saturation has not occurred when ΔS < TH4.

[0053] FIG. 9 schematically illustrates how to determine the ejection amount allowable range (Dt_min to Dt_max) from the ejection amount reference value Dt_goal, which is the reference for the allowable range of the ejection amount upper limit value Dt_final. In FIG. 9, the horizontal axis represents the ink ejection amount Duty, and the vertical axis represents the color development value S. FIG. 10 schematically illustrates the correspondence between the ink ejection amount Duty and the colorimetric value Lab. In this specific example, in order to maintain the color development property of the new model of the printer 200 to be equivalent to that of the old model, etc., the target ejection amount reference value Dt_goal is first set. The ejection amount reference value Dt_goal is set for each of the primary colors and secondary colors, for example. Note that the ejection amount reference value Dt_goal may also be set for the tertiary color, or may be set for each of C, M, Y, and K for the primary colors, or may be set for each color combination for the secondary colors. When the target is the old model, the ejection amount reference value Dt_goal may be the ejection amount upper limit value determined in the old model, or may be the ejection amount upper limit value determined from the measurement results of the test pattern formed by the old model. Also, the ejection amount reference value Dt_goal may be set according to the user's request regardless of the old model.

[0054] The host device 100 sets the allowable discharge amount range (Dt_min to Dt_max) based on each discharge amount reference value Dt_goal. Here, as shown in Fig. 10, the colorimetric value Lab of a solid patch whose ink discharge amount duty is the discharge amount reference value Dt_goal is set as the reference colorimetric value Lab_goal, the colorimetric value Lab of a solid patch whose ink discharge amount duty is the minimum discharge amount Dt_min is set as Lab_L, the colorimetric value Lab of a solid patch whose ink discharge amount duty is the maximum discharge amount Dt_max is set as Lab_U, and the threshold value of the color difference ΔE based on the reference colorimetric value Lab_goal is set as ΔEa. The color difference ΔE is calculated using the CIE DE2000 color difference formula ΔE 2000 Alternatively, it may be the square root of the sum of the squares of the L value, the a value, and the b value. The host device 100 determines the ink discharge amount duty of the patch with the smallest ink discharge amount duty among the patches with a color difference ΔE equal to or less than the threshold value ΔEa as the minimum discharge amount Dt_min. The minimum discharge amount Dt_min corresponds to the lower limit of the allowable value represented by the threshold value ΔEa of the color difference ΔE based on the reference colorimetric value Lab_goal. The host device 100 also determines the ink discharge amount duty of the patch with the largest ink discharge amount duty among the patches with a color difference ΔE equal to or less than the threshold value ΔEa as the maximum discharge amount Dt_max. The maximum discharge amount Dt_max corresponds to the upper limit of the allowable value represented by the threshold value ΔEa of the color difference ΔE based on the reference colorimetric value Lab_goal. The threshold value ΔEa of the color difference ΔE can be determined in advance by having multiple testers perform sensory evaluations of multiple patches printed on the medium ME0. In general, if the color difference ΔE between patches is about 2, it can be said that there is almost no color difference between the patches. Therefore, the threshold value ΔEa may be about 2.

[0055] Furthermore, the host device 100 determines a provisional ejection volume upper limit value Dt_auto based on at least one of the non-occurrence upper limit values (Dt_1 to Dt_3) from viewpoints other than color development. The provisional ejection volume upper limit value Dt_auto may be within the ejection volume allowable range (Dt_min to Dt_max) or may be outside the ejection volume allowable range (Dt_min to Dt_max). Therefore, the host device 100 determines a final ejection volume upper limit value Dt_final within the ejection volume allowable range (Dt_min to Dt_max) based on the ejection volume allowable range (Dt_min to Dt_max) and the provisional ejection volume upper limit value Dt_auto. The ejection volume upper limit value Dt_final is determined, for example, as follows. When Dt_auto ≤ Dt_min, Dt_final = Dt_min When Dt_min < Dt_auto < Dt_max, Dt_final = Dt_auto When Dt_auto ≥ Dt_max, Dt_final = Dt_max The above determination method is merely an example. For example, taking a ejection volume slightly larger than the ejection volume minimum value Dt_min within the ejection volume allowable range (Dt_min to Dt_max) as Dt_amin, when Dt_auto ≤ Dt_amin, the ejection volume upper limit value Dt_final may be determined to be the ejection volume Dt_amin. Taking a ejection volume slightly smaller than the ejection volume maximum value Dt_max within the ejection volume allowable range (Dt_min to Dt_max) as Dt_amax, when Dt_auto ≥ Dt_amax, the ejection volume upper limit value Dt_final may be determined to be the ejection volume Dt_amax.

[0056] (3) Specific example of ink ejection volume upper limit value determination process: Fig. 11 shows a schematic example of the ink discharge amount upper limit determination process for determining the ink discharge amount upper limit Dt_final. Fig. 12 shows a schematic example of a UI (user interface) screen displayed in step S102 of the ink discharge amount upper limit determination process. Fig. 13 shows a schematic example of the print process performed by the printer 200 in step S104 of the ink discharge amount upper limit determination process. The ink discharge amount upper limit determination process will be described below with reference to Figs. 1 to 10. The ink discharge amount upper limit determination process of this specific example is performed by the host device 100 including the control unit 110 as shown in FIG. 1. The ink discharge amount upper limit determination process starts when the host device 100 accepts an operation for determining the discharge amount upper limit Dt_final through the input device 115. Here, steps S102 to S108 and S116 to S118 correspond to the discharge amount upper limit determination unit 315 and the discharge amount upper limit determination function FU5. Step S110 corresponds to the overflow upper limit calculation unit 311 and the overflow upper limit calculation function FU1. Step S112 corresponds to the bleeding upper limit calculation unit 312 and the bleeding upper limit calculation function FU2. Step S114 corresponds to the coagulation upper limit calculation unit 313 and the coagulation upper limit calculation function FU3. Step S104 corresponds to the test pattern formation process ST1. Steps S102 and S106 to S108 correspond to the allowable range determination process ST2. Steps S106 and S110 to S116 correspond to the tentative decision step ST3. Step S118 corresponds to the first final decision step ST4. Hereinafter, the word "step" may be omitted, and the step code may be shown in parentheses.

[0057] 12 on the display device 116, and acquires the discharge amount reference value Dt_goal, the color difference ΔE threshold value ΔEa, etc. (S102). The UI screen 700 has a medium type selection field 701, a target setting selection area 702, a primary color discharge amount reference value input field 703, a secondary color discharge amount reference value input field 704, a test pattern read button 705, an allowable color difference input field 706, a consideration factor selection area 707, an OK button 708, etc.

[0058] In the medium type selection field 701, the host device 100 accepts the setting of any one of medium types such as plain paper, photo paper, cloth, etc. The user can select any one of a plurality of medium types by operating the medium type selection field 701 with the input device 115. In the target setting selection area 702, the host device 100 accepts the selection of either "set" or "do not set." The user can select "set" or "do not set" by operating the target setting selection area 702 with the input device 115. When the host device 100 accepts "set," it performs the processes of S104 to S118. When the host device 100 accepts "do not set," it does not set the permissible discharge amount range (Dt_min to Dt_max), and performs a separate process not shown in FIG. 11 to determine the discharge amount upper limit value Dt_final. This separate process will be described later.

[0059] The host device 100 accepts input of the discharge volume reference value Dt_goal for the primary color in a primary color discharge volume reference value input field 703. The user can input the discharge volume reference value Dt_goal for the primary color by operating the primary color discharge volume reference value input field 703 with the input device 115. Note that the primary color discharge volume reference value input field 703 may be provided for each primary color. In the secondary color discharge amount reference value input field 704, the host device 100 accepts input of the discharge amount reference value Dt_goal for the secondary color. The user can input the discharge amount reference value Dt_goal for the secondary color by operating the secondary color discharge amount reference value input field 704 with the input device 115. Note that the secondary color discharge amount reference value input field 704 may be provided for each secondary color. Of course, the host device 100 may also accept input of the discharge amount reference value Dt_goal for the tertiary color in a tertiary color discharge amount reference value input field (not shown).

[0060] The test pattern read button 705 is an operation area for determining the primary and secondary color discharge volume reference values ​​Dt_goal by measuring the test pattern 500 formed by the old model of the printer 200. When the host device 100 accepts the operation of the test pattern read button 705, it may cause the colorimetric unit 262 to measure the color of the solid pattern string by the old model, and cause the imaging unit 261 to image the line pattern string by the old model. Then, the host device 100 may determine the "color saturation non-occurrence upper limit value" based on the colorimetric information 334, determine the non-occurrence upper limit values ​​(Dt_1 to Dt_3) based on the imaging information 333, and determine the discharge volume reference value Dt_goal based on at least one of the "color saturation non-occurrence upper limit value" and the non-occurrence upper limit values ​​(Dt_1 to Dt_3). In the allowable color difference input field 706, the host device 100 accepts input of a threshold value ΔEa of the color difference ΔE based on the reference colorimetric value Lab_goal corresponding to the discharge amount reference value Dt_goal. The user can input the threshold value ΔEa by operating the allowable color difference input field 706 with the input device 115. The host device 100 may display a default threshold value ΔEa in the allowable color difference input field 706. Note that the allowable color difference input field 706 may be provided separately for primary colors and secondary colors.

[0061] In the consideration factor selection area 707, the host device 100 accepts settings of whether or not to consider "ink overflow", whether or not to consider "ink bleeding", and whether or not to consider "ink coagulation". By operating the consideration factor selection area 707 with the input device 115, the user can select whether or not to consider "ink overflow", whether or not to consider "ink bleeding", and whether or not to consider "ink coagulation".

[0062] When the host device 100 accepts the operation of the OK button 708 by the input device 115, the operation contents on the UI screen 700 are stored in at least one of the RAM 113 and the storage device 114. As a result, the host device 100 acquires the discharge amount reference value Dt_goal and acquires the threshold value ΔEa of the color difference ΔE. After S102, the host device 100 performs a process of making the printer 200 print a test pattern 500 including a plurality of patches with different ink discharge amount duties (S104). The host device 100 transmits the solid pattern data 331 and the lined pattern data 332 shown in FIG. 1 to the printer 200. Here, these data (331, 332) are assumed to be RGB data. As shown in FIG. 13, the printer 200 first performs a resolution conversion process of converting the solid pattern data 331 and the lined pattern data 332 to a printing resolution (S202). If these data (331, 332) are the printing resolution, the resolution conversion process is not necessary. Next, the printer 200 performs a color conversion process to convert the solid pattern data 331 and the lined pattern data 332 into ink amount data (S204). Note that if these data (331, 332) are ink amount data, the color conversion process is not necessary. Next, the printer 200 performs a halftone process to convert the ink amount data into binary or quaternary dot data (S206). Note that if the solid pattern data 331 or the lined pattern data 332 is dot data, the halftone process is not necessary. If necessary, the printer 200 performs a rasterization process to rearrange the dot data in the printing order. Finally, the printer 200 generates a drive signal according to the dot data, and forms a test pattern 500 including the solid pattern arrays P21 to P25 corresponding to the solid pattern data 331 and the lined pattern arrays P11 to P16 corresponding to the lined pattern data 332 on the medium ME0 (S208). The processes of S202 to S206 may be performed by the host device 100, the processes of S202 to S204 may be performed by the host device 100, or the process of S202 may be performed by the host device 100.

[0063] After printing the test pattern 500, the host device 100 causes the printer 200 to perform color measurement and imaging, and acquires color measurement information 334 of the solid pattern arrays P21 to P25 and imaging information 333 of the line pattern arrays P11 to P16 from the printer 200 (S106). Upon receiving the instruction for color measurement and imaging, the printer 200 backfeeds the medium ME0, measures the color of the patches included in the solid pattern arrays P21 to P25 with the color measurement unit 262, and images the patches included in the line pattern arrays P11 to P16 with the imaging unit 261. When the printer 200 transmits the color measurement information 334 from the color measurement unit 262 and the imaging information 333 from the imaging unit 261 to the host device 100, the host device 100 acquires the color measurement information 334 and the imaging information 333 and stores them in the storage device 114. Furthermore, the host device 100 calculates a color value S from the color measurement values ​​Lab as shown in FIG.

[0064] Next, the host device 100 determines the allowable range of the discharge amount (Dt_min to Dt_max) based on the colorimetric information 334, which varies according to the ink discharge amount duty, and the discharge amount reference value Dt_goal (S108). As shown in Figures 9 and 10, the host device 100 determines the ink discharge amount duty of the patch with the smallest ink discharge amount duty among the patches with a color difference ΔE equal to or less than the threshold ΔEa as the minimum discharge amount Dt_min. Also, the host device 100 determines the ink discharge amount duty of the patch with the largest ink discharge amount duty among the patches with a color difference ΔE equal to or less than the threshold ΔEa as the maximum discharge amount Dt_max.

[0065] Next, the host device 100 obtains the overflow degree V1 based on the imaging information 333, and determines the non - overflow upper limit value Dt_1 by applying the overflow determination threshold TH1 to the overflow degree V1 (S110). For example, as shown in FIG. 1, the overflow upper limit value calculation unit 311 first obtains, for each line pattern column P11 - P16, the maximum ink ejection amount for which V1 < TH1 as the non - overflow upper limit value. Next, the overflow upper limit value calculation unit 311 determines the non - overflow upper limit value Dt_1 of the primary color based on the non - overflow upper limit values of the primary color line pattern columns P11 - P15, and determines the non - overflow upper limit value Dt_1 of the secondary color based on the non - overflow upper limit value of the secondary color line pattern column P16. The non - overflow upper limit value Dt_1 of the primary color may be the minimum value of the non - overflow upper limit values of the line pattern columns P11 - P15, or may be the average value of the non - overflow upper limit values of the line pattern columns P11 - P15. The non - overflow upper limit value Dt_1 of the secondary color can also be calculated in the same manner as the non - overflow upper limit value Dt_1 of the primary color.

[0066] Next, the host device 100 obtains the bleeding degree V2 based on the imaging information 333, and determines the non - bleeding upper limit value Dt_2 by applying the bleeding determination threshold TH2 to the bleeding degree V2 (S112). For example, as shown in FIG. 1, the bleeding upper limit value calculation unit 312 first obtains, for each line pattern column P11 - P16, the maximum ink ejection amount for which V2 < TH2 as the non - bleeding upper limit value. Next, the bleeding upper limit value calculation unit 312 determines the non - bleeding upper limit value Dt_2 of the primary color based on the non - bleeding upper limit values of the primary color line pattern columns P11 - P15, and determines the non - bleeding upper limit value Dt_2 of the secondary color based on the non - bleeding upper limit value of the secondary color line pattern column P16. The non - bleeding upper limit value Dt_2 of the primary color may be the minimum value of the non - bleeding upper limit values of the line pattern columns P11 - P15, or may be the average value of the non - bleeding upper limit values of the line pattern columns P11 - P15. The non - bleeding upper limit value Dt_2 of the secondary color can also be calculated in the same manner as the non - bleeding upper limit value Dt_2 of the primary color.

[0067] Next, the host device 100 obtains the degree of aggregation V3 based on the imaging information 333, and determines the non-occurrence upper limit value Dt_3 of aggregation by applying the aggregation determination threshold TH3 to the degree of aggregation V3 (S114). For example, as shown in FIG. 1, the aggregation upper limit value calculation unit 313 first obtains, as the non-occurrence upper limit value of aggregation, the maximum ink ejection amount for which V3 < TH3 for each line pattern column P11 to P16. Next, the aggregation upper limit value calculation unit 313 determines the non-occurrence upper limit value Dt_3 of the primary color based on the non-occurrence upper limit values of the primary color line pattern columns P11 to P15, and determines the non-occurrence upper limit value Dt_3 of the secondary color based on the non-occurrence upper limit value of the secondary color line pattern column P16. The non-occurrence upper limit value Dt_3 of the primary color may be the minimum value of the non-occurrence upper limit values of the line pattern columns P11 to P15, or may be the average value of the non-occurrence upper limit values of the line pattern columns P11 to P15. The non-occurrence upper limit value Dt_3 of the secondary color can also be calculated in the same manner as the non-occurrence upper limit value Dt_3 of the primary color.

[0068] Next, the host device 100 determines a provisional ejection amount upper limit value Dt_auto, which is a provisional value of the ejection amount upper limit value Dt_final, based on at least one of the non-occurrence upper limit values (Dt_1 to Dt_3) (S116). For example, when a plurality of items are selected in the consideration element selection area 707 shown in FIG. 12, the host device 100 may determine the minimum value or the average value of the non-occurrence upper limit values corresponding to the selected items as the provisional ejection amount upper limit value Dt_auto. When only one item is selected in the consideration element selection area 707 shown in FIG. 12, the host device 100 may determine the non-occurrence upper limit value corresponding to the selected item as the provisional ejection amount upper limit value Dt_auto. As described above, the host device 100 determines the provisional ejection amount upper limit value Dt_auto based on the imaging information 333.

[0069] Finally, the host device 100 determines the ejection amount upper limit value Dt_final so as to be equal to or greater than the ejection amount minimum value Dt_min and equal to or less than the ejection amount maximum value Dt_max based on the ejection amount minimum value Dt_min, the ejection amount maximum value Dt_max, and the provisional ejection amount upper limit value Dt_auto (S118). When Dt_auto ≤ Dt_min Dt_final = Dt_min When Dt_min < Dt_auto < Dt_max, Dt_final = Dt_auto When Dt_auto ≥ Dt_max, Dt_final = Dt_max For example, the host device 100 determines the upper limit value Dt_final of the discharge amount according to the above formula for primary colors, and determines the upper limit value Dt_final of the discharge amount according to the above formula for secondary colors.

[0070] The determined upper limit value Dt_final of the discharge amount is used for creating a color conversion LUT referred to during color conversion processing, etc.

[0071] From the above, the upper limit value Dt_final of the discharge amount is determined within the allowable range (Dt_min~Dt_max) based on the discharge amount reference value Dt_goal, and within this allowable range (Dt_min~Dt_max), the image quality viewpoints other than color development are considered as much as possible in the determination. Therefore, in this specific example, it is possible to determine the upper limit value of the discharge amount that takes into account other image quality viewpoints as much as possible while obtaining the desired color development. As a result, when switching the printer to a new model, by setting the discharge amount reference value Dt_goal to the upper limit value Dt_final of the old model or in the vicinity thereof, the color reproducibility of the new model can be made equivalent to that of the old model. At that time, the newly determined upper limit value Dt_final of the discharge amount takes into account the image quality viewpoints of "overflow", "bleeding", and "agglomeration".

[0072] (4) Application example: The printing device 1 only needs to have the ability to perform the processes of S102~S118 shown in FIG. 11, and may determine the upper limit value Dt_final of the discharge amount without performing at least some of the processes of S102~S118. Fig. 14 shows a schematic example of an ink discharge amount upper limit determination process including a process performed when "Do not set" is selected in the target setting selection area 702 shown in Fig. 12. Here, S302 and S306 correspond to S102 shown in Fig. 11. S310 to S320 correspond to the second final determination step ST5. When "Set" is selected in the target setting selection area 702, this means that the process setting is the first setting, which means that the discharge amount reference value Dt_goal is used. When "Do not set" is selected in the target setting selection area 702, this means that the process setting is the second setting, which means that the discharge amount reference value Dt_goal is not used.

[0073] When the ink ejection amount upper limit determination process shown in Fig. 14 starts, the host device 100 displays the UI screen 700 shown in Fig. 12 on the display device 116 (S302). Next, the host device 100 determines whether or not to use the ejection amount reference value Dt_goal (S304). When "Set" is selected in the target setting selection area 702 shown in Fig. 12, the host device 100 acquires the discharge amount reference value Dt_goal, the threshold value ΔEa of the color difference ΔE, and the like from the discharge amount reference value input fields (703, 704) (S306), and performs the processes of S104 to S118 shown in Fig. 11. Therefore, when the processing setting is the first setting, the host device 100 determines the allowable range (Dt_min to Dt_max) based on the color measurement information 334 and the discharge amount reference value Dt_goal, and determines the provisional discharge amount upper limit value Dt_auto based on the imaging information 333. Then, the host device 100 determines the discharge amount upper limit value Dt_final so as to be equal to or greater than the minimum discharge amount Dt_min and equal to or less than the maximum discharge amount Dt_max, based on the allowable range (Dt_min to Dt_max) and the provisional discharge amount upper limit value Dt_auto.

[0074] When "Do not set" is selected in the target setting selection area 702 shown in FIG. 12, the host device 100 performs a process of making the printer 200 print the test pattern 500 in the same manner as the process of S104 shown in FIG. 11 (S308). Next, the host device 100 acquires the colorimetric information 334 of the solid pattern sequence P21-P25 and the imaging information 333 of the line pattern sequence P11-P16 from the printer 200 in the same manner as the process of S106 shown in FIG. 11 (S310). Next, the host device 100 determines the overflow non-occurrence upper limit value Dt_1 by applying the overflow determination threshold value TH1 to the overflow degree V1 obtained from the imaging information 333 in the same manner as the process of S110 shown in FIG. 11 (S312). Next, the host device 100 determines the overflow non-occurrence upper limit value Dt_2 by applying the bleeding determination threshold value TH2 to the bleeding degree V2 obtained from the imaging information 333 in the same manner as the process of S112 shown in FIG. 11 (S314). Next, the host device 100 determines the aggregation non-occurrence upper limit Dt_3 by applying the aggregation determination threshold TH3 to the aggregation degree V3 obtained from the imaging information 333 in the same manner as in the process of S114 shown in FIG. 11 (S316). The non-occurrence upper limit values ​​(Dt_1 to Dt_3) are examples of second provisional discharge amount upper limit values, which are provisional values ​​of the discharge amount upper limit value from the viewpoint of the imaging information 333.

[0075] Next, the host device 100 obtains a change ΔS based on the color development value S (see FIG. 8) obtained from the color measurement information 334 from the color measurement unit 262, and determines a color saturation non-occurrence upper limit value Dt_4 by applying a color saturation determination threshold TH4 (TH4 > 0) to the change ΔS (S318). The color saturation non-occurrence upper limit value Dt_4 means the upper limit value of the ink ejection amount at which ink color saturation does not occur. The color saturation determination threshold TH4 used for determining the presence or absence of ink color saturation can be determined in advance by performing a sensory evaluation of a plurality of test patterns printed on the medium ME0 by a plurality of testers. For example, the tester performs a sensory evaluation such as visually recognizing a plurality of solid pattern columns printed on the medium ME0 and selecting a patch where the occurrence of ink color saturation can be visually recognized. The results of performing the same sensory evaluation on a plurality of testers are statistically analyzed to determine the color saturation determination threshold TH4. When finally determining the color saturation determination threshold TH4 from the analysis results, a histogram with the change ΔS of the color development value S as a bin may be created, and the width of the peak frequency may be used as the color saturation determination threshold TH4, or the weighted average value may be used as the color saturation determination threshold TH4. The design specifications of the printing device 1 may be taken into account for the color saturation determination threshold TH4. By determining the presence or absence of ink bleeding according to the obtained color saturation determination threshold TH4, a result that conforms to human perception can be obtained. The determined color saturation determination threshold TH4 is stored in the storage device 114.

[0076] For example, as shown in FIG. 1, the color saturation upper limit value calculation unit 314 first obtains, as the color saturation non-occurrence upper limit value, the maximum ink ejection amount for which ΔS < TH4 for each solid pattern column P21 to P25. Next, the color saturation upper limit value calculation unit 314 determines the color saturation non-occurrence upper limit value Dt_4 of the primary color based on the color saturation non-occurrence upper limit values of the primary color solid pattern columns P21 to P24, and determines the color saturation non-occurrence upper limit value Dt_4 of the secondary color based on the color saturation non-occurrence upper limit value of the secondary color solid pattern column P25. The color saturation non-occurrence upper limit value Dt_4 of the primary color may be the minimum value of the color saturation non-occurrence upper limit values of the solid pattern columns P21 to P24, or may be the average value of the color saturation non-occurrence upper limit values of the solid pattern columns P21 to P24. The color saturation non-occurrence upper limit value Dt_4 of the secondary color can also be calculated in the same manner as the color saturation non-occurrence upper limit value Dt_4 of the primary color. The color saturation non-occurrence upper limit Dt_4 is an example of a first provisional upper limit of the ejection rate, which is a provisional value of the upper limit of the ejection rate from the viewpoint of the color measurement information 334.

[0077] Finally, the host device 100 determines the discharge amount upper limit Dt_final based on at least one of the color saturation non-occurrence upper limit Dt_4 in terms of the color measurement information 334 and the non-occurrence upper limit values ​​(Dt_1 to Dt_3) in terms of the imaging information 333 (S320). For example, when "Not set" is selected in the target setting selection area 702 of the UI screen 700 shown in FIG. 12, "ink color saturation" is considered, and items selected in the consideration element selection area 707 are considered for other image quality elements. When multiple items are selected in the consideration element selection area 707, the host device 100 may determine the minimum or average value of the non-occurrence upper limit values ​​corresponding to the selected items as the second provisional discharge amount upper limit. In this case, the host device 100 may determine the smaller value of the color saturation non-occurrence upper limit Dt_4 and the second provisional discharge amount upper limit, or the average value of the color saturation non-occurrence upper limit Dt_4 and the second provisional discharge amount upper limit, as the discharge amount upper limit Dt_final. If no item is selected in the consideration factor selection area 707, the host device 100 may determine the upper limit value Dt_4 at which color saturation does not occur as the discharge amount upper limit value Dt_final. 12, "ink color saturation" is not taken into consideration, and other image quality elements are taken into consideration with respect to the items selected in the consideration element selection area 707. When multiple items are selected in the consideration element selection area 707, the host device 100 may determine the minimum or average value of the non-occurrence upper limit values ​​corresponding to the selected items as the second provisional ejection amount upper limit value, and therefore the ejection amount upper limit value Dt_final.

[0078] The example shown in FIG. 14 allows the user to select whether or not to determine the upper limit of the ejection amount while taking into account other aspects of image quality as much as possible while still obtaining the desired color development, thereby improving user convenience.

[0079] Fig. 15 shows a schematic example of an ink ejection amount upper limit determination process that omits the processes of S110 to S118 for determining the provisional ejection amount upper limit Dt_auto when Dt_min=Dt_max or the allowable range (Dt_min to Dt_max) is narrow in the allowable range determination process of S108 shown in Fig. 11. Here, S404 corresponds to the third final determination step ST6. When the ink ejection amount upper limit determination process shown in Fig. 15 starts, the host device 100 performs the processes of S102 to S108 shown in Fig. 11 to determine the minimum ejection amount Dt_min and the maximum ejection amount Dt_max. Here, a threshold value for a difference value Dt_max-Dt_min obtained by subtracting the minimum ejection amount Dt_min from the maximum ejection amount Dt_max is set to a predetermined value ΔDt (ΔDt>0).

[0080] Next, the host device 100 determines whether the difference value Dt_max-Dt_min is greater than a predetermined value ΔDt (S402). If Dt_max-Dt_min>ΔDt, the host device 100 performs the processes of S110 to S118 shown in Fig. 11. Therefore, if Dt_max-Dt_min>ΔDt, the host device 100 determines the provisional discharge amount upper limit Dt_auto based on the imaging information 333, and determines the discharge amount upper limit Dt_final so as to be equal to or greater than the minimum discharge amount Dt_min and equal to or less than the maximum discharge amount Dt_max, based on the allowable range (Dt_min to Dt_max) and the provisional discharge amount upper limit Dt_auto.

[0081] If Dt_max-Dt_min≦ΔDt, the host device 100 determines the discharge amount reference value Dt_goal as the discharge amount upper limit value Dt_final (S404) and ends the ink discharge amount upper limit value determination process. Note that in S404, the host device 100 may determine the minimum discharge amount Dt_min or the maximum discharge amount Dt_max as the discharge amount upper limit value Dt_final. In addition, in S404, the host device 100 may determine the average value of the discharge amount reference value Dt_goal and the minimum discharge amount Dt_min, the average value of the discharge amount reference value Dt_goal and the maximum discharge amount Dt_max, the average value of the discharge amount reference value Dt_goal, the minimum discharge amount Dt_min and the maximum discharge amount Dt_max, or the like as the discharge amount upper limit value Dt_final. When Dt_max-Dt_min≦ΔDt, the image quality aspects of "overflow", "bleeding" and "aggregation" are not taken into account to a great extent even if the processes of S110 to S118 shown in Fig. 11 are performed. Therefore, the example shown in Fig. 15 can shorten the calculation time for determining the discharge rate upper limit value Dt_final when Dt_max-Dt_min≦ΔDt.

[0082] In addition, when the threshold value ΔEa of the color difference ΔE is small, for example, 1 or less, in the allowable range determination process of S108 shown in Fig. 11, Dt_min=Dt_max or the allowable range (Dt_min to Dt_max) becomes narrow, and usually Dt_max-Dt_min≦ΔDt. Therefore, when the threshold value ΔEa acquired in the process of S102 shown in Fig. 11 is equal to or less than a second predetermined value (for example, a value between 0 and 1), the host device 100 may omit the processes of S110 to S118 for determining the provisional discharge amount upper limit value Dt_auto. In addition, when the threshold value ΔEa acquired in the process of S102 is equal to or less than the second predetermined value, the host device 100 may determine the discharge amount reference value Dt_goal to be the discharge amount upper limit value Dt_final without performing the processes of S104 to S118.

[0083] (5) Variation: The present invention contemplates various modifications. For example, the ink color combination is not limited to C, M, Y, and K, and may include, in addition to C, M, Y, and K, one or more colors selected from Lc (light cyan) having a lower density than C, Lm (light magenta) having a lower density than M, Dy (dark yellow) having a higher density than Y, Lk (light black) having a lower density than K, Or (orange), Gr (green), transparent colors, etc. This technology is also applicable when some of C, M, Y, and K are not included in the ink color combination. The entity that performs the ink discharge amount upper limit determination process is not limited to a CPU, and may be an electronic component other than a CPU, such as an ASIC (Application Specific Integrated Circuit), etc. Of course, multiple CPUs may work together to perform the ink discharge amount upper limit determination process, or a CPU and another electronic component (e.g., an ASIC) may work together to perform the ink discharge amount upper limit determination process. The above-mentioned processes can be changed as appropriate, such as by changing the order of the processes. For example, in the ink discharge amount upper limit value determination process shown in Fig. 11, the process of S102 may be performed immediately after the process of S104 or S106, and the process order of S110, S112, and S114 can be changed arbitrarily. In the above-described processing, for example, a determination of whether or not it is "greater than" can be replaced with a determination of whether or not it is "greater than," and a determination of whether or not it is "less than" can be replaced with a determination of whether or not it is "less than" or not. Such replacement of determinations is also included in the present technology.

[0084] The reading unit that reads at least some of the patches included in the test pattern 500 is not limited to the imaging unit 261, but may be an image reading unit such as a scanner. The control unit 110 may obtain the overflow degree V1 and the aggregation degree V3 based on the results of reading a plurality of patches included in the solid pattern sequences P21 to P25. Therefore, a reading unit such as the imaging unit 261 may read all the patches included in the test pattern 500, and the control unit 110 may determine the provisional discharge amount upper limit value Dt_auto based on the results of reading all the patches. The control unit 110 may determine the allowable range (Dt_min to Dt_max) based on the color measurement results of the solid area 531 of the patch 510 shown in Fig. 5 and the reference value of the discharge amount Dt_goal. Therefore, the colorimetric unit 262 may measure the color of all the patches included in the test pattern 500, and the control unit 110 may determine the allowable range (Dt_min to Dt_max) based on the color measurement results of all the patches and the reference value of the discharge amount Dt_goal.

[0085] The control unit 110 may determine the allowable range (Dt_min to Dt_max) based on the allowable value of the brightness difference between patches, the allowable value of the saturation difference between patches, and the like, instead of the allowable value of the color difference ΔE between patches. Furthermore, the control unit 110 may determine the allowable range (Dt_min to Dt_max) based on the discharge amount reference value Dt_goal without using the color measurement results of the patch. For example, the control unit 110 may use a positive discharge amount difference allowable value based on the discharge amount reference value Dt_goal to determine the minimum discharge amount Dt_min as a value obtained by subtracting the discharge amount difference allowable value from the discharge amount reference value Dt_goal, and may determine the maximum discharge amount Dt_max as a value obtained by adding the discharge amount difference allowable value to the discharge amount reference value Dt_goal.

[0086] (6) Conclusion: As described above, according to the present invention, it is possible to provide a technique that can determine the upper limit of the ejection amount while taking into account other aspects of image quality as much as possible while obtaining the desired color development. Of course, even a technique that is composed only of the constituent elements according to the independent claims can obtain the basic functions and effects described above. In addition, configurations in which the configurations disclosed in the above examples are substituted with each other or the combination is changed, configurations in which the configurations disclosed in the publicly known techniques and the above examples are substituted with each other or the combination is changed, etc. The present invention also includes these configurations. [Explanation of symbols]

[0087] 1...printing device, 100...host device, 110...controller, 200...printer, 210...controller, 230...print head, 236...ink, 237...ink droplets, 250...driving section, 261...imaging section, 262...colorimetry section, 311...overflow upper limit calculation section, 312...bleed upper limit calculation section, 313...coagulation upper limit calculation section, 314...color saturation upper limit calculation section, 315...ejection amount upper limit determination section, 333...imaging information, 334 ...colorimetry information, 500...test pattern, 510-515, 521-525...patches, 531...solid area, 532...line area, 533...center, 534...periphery, 700...UI screen, D1...first direction, D2...second direction, d1, d2...distance, DT0-DT4...dots, Dt_1...overflow no upper limit, Dt_2...bleed no upper limit, Dt_3...aggregation no upper limit, Dt_4...color saturation no upper limit, Dt_ auto...Temporary upper limit of discharge amount, Dt_final...Upper limit of discharge amount, Dt_goal...Standard value of discharge amount, Dt_max...Maximum value of discharge amount, Dt_min...Minimum value of discharge amount, IM0...Print image, Lab_goal...Standard color measurement value, ME0, ME1, ME2...Media, P11~P16...Line pattern array, P21~P25...Solid pattern array, PR0...Print control program, S...Color value, ST1...Test pattern formation process process, ST2...tolerance range determination process, ST3...tentative determination process, ST4...first final determination process, ST5...second final determination process, ST6...third final determination process, t1, t2...timing, TH1...overflow determination threshold, TH2...bleeding determination threshold, TH3...coagulation determination threshold, TH4...color saturation determination threshold, V1...overflow degree, V2...bleeding degree, V3...coagulation degree, w1, w2...width, ΔDt...predetermined value, ΔEa...threshold, ΔS...change in color value.

Claims

1. 1. A method for determining an upper limit of a discharge amount per unit area of ​​a liquid discharged from a print head onto a medium, comprising: a test pattern forming step of forming a test pattern including a plurality of patches having different ejection amounts on the medium; an allowable range determination step of acquiring a discharge amount reference value that is a reference for an allowable range of the upper limit value, and determining a minimum discharge amount value that is a minimum value of the allowable range and a maximum discharge amount value that is a maximum value of the allowable range based on the discharge amount reference value; a provisional determination step of acquiring a reading result of at least a part of the plurality of patches and determining a provisional ejection amount upper limit value, which is a provisional value of the upper limit value, based on the reading result; a first final determination step of determining the upper limit value based on the minimum discharge amount value, the maximum discharge amount value, and the provisional upper limit value, so that the upper limit value is equal to or greater than the minimum discharge amount value and equal to or less than the maximum discharge amount value; A method for determining an upper limit of a discharge amount, comprising:

2. 2. The method for determining an upper limit of an ejection volume according to claim 1, wherein in the acceptable range determination process, a color measurement result of at least a portion of the plurality of patches is obtained, the color measurement result being different from the reading result, and the minimum ejection volume value and the maximum ejection volume value are determined based on the color measurement result and the ejection volume reference value.

3. 3. The method for determining an upper discharge volume value according to claim 2, wherein the tolerance range determination process accepts input of a tolerance value of color difference based on a reference colorimetric value corresponding to the discharge volume reference value, and determines the minimum discharge volume value corresponding to the lower limit of the tolerance value and the maximum discharge volume value corresponding to the upper limit of the tolerance value based on the reference colorimetric value, based on the colorimetric result which differs depending on the discharge volume.

4. In the first final determination step, When the provisional discharge amount upper limit value is greater than the minimum discharge amount value and smaller than the maximum discharge amount value, the upper limit value is determined as the provisional discharge amount upper limit value; If the provisional discharge amount upper limit value is equal to or less than the discharge amount minimum value, the upper limit value is determined to be the discharge amount minimum value; 3. The method for determining an upper discharge amount limit according to claim 1, wherein when the provisional upper discharge amount limit is equal to or greater than the maximum discharge amount, the upper discharge amount limit is determined to be the maximum discharge amount.

5. The discharge amount upper limit value determination method includes, when a processing setting is a first setting which means use of the discharge amount reference value, In the allowable range determination step, the minimum discharge amount value and the maximum discharge amount value are determined based on the discharge amount reference value; In the provisional determination step, the provisional ejection amount upper limit value is determined based on the reading result, in the first final determination step, the upper limit value is determined based on the minimum discharge amount value, the maximum discharge amount value, and the provisional upper limit value, so that the upper limit value is equal to or greater than the minimum discharge amount value and equal to or less than the maximum discharge amount value; The discharge amount upper limit value determination method includes, when the processing setting is a second setting which means that the discharge amount reference value is not used, The method for determining an upper discharge amount limit value according to claim 1, further comprising a second final determination step of acquiring a color measurement result of at least a portion of the plurality of patches, the color measurement result being different from the reading result, determining a first provisional ejection amount limit value which is a provisional value of the upper limit value from the viewpoint of the color measurement result based on the color measurement result, acquiring the reading result of at least a portion of the plurality of patches, determining a second provisional ejection amount limit value which is a provisional value of the upper limit value from the viewpoint of the reading result based on the reading result, and determining the upper limit value based on at least one of the first provisional ejection amount limit value and the second provisional ejection amount limit value.

6. In the provisional determination step, when a difference value obtained by subtracting the minimum discharge amount value from the maximum discharge amount value is greater than a predetermined value, the provisional discharge amount upper limit value is determined based on the reading result; in the first final determination step, when the difference value is greater than the predetermined value, the upper limit value is determined based on the minimum discharge amount value, the maximum discharge amount value, and the provisional upper limit value so as to be equal to or greater than the minimum discharge amount value and equal to or less than the maximum discharge amount value, The method for determining an upper discharge volume limit value according to claim 1 or claim 2, further comprising a third final determination step of determining the upper limit value based on at least one of the reference discharge volume value, the minimum discharge volume value, and the maximum discharge volume value when the difference value is equal to or less than the predetermined value, so that the upper limit value is greater than or equal to the minimum discharge volume value and less than or equal to the maximum discharge volume value.

7. A print head that ejects liquid onto a medium; a control unit that performs control to form a test pattern including a plurality of patches with different ejection amounts per unit area of ​​the liquid on the medium, and performs processing to determine an upper limit value of the ejection amount; A reading unit that reads at least a part of the plurality of patches, The control unit is a first process of acquiring a discharge amount reference value that is a reference for an allowable range of the upper limit value, and determining a minimum discharge amount value that is a minimum value of the allowable range and a maximum discharge amount value that is a maximum value of the allowable range based on the discharge amount reference value; a second process of acquiring a reading result of at least a part of the plurality of patches from the reading unit, and determining a provisional ejection amount upper limit value, which is a provisional value of the upper limit value, based on the reading result; a third process of determining the upper limit value based on the minimum discharge amount value, the maximum discharge amount value, and the provisional upper limit value so that the upper limit value is equal to or greater than the minimum discharge amount value and equal to or less than the maximum discharge amount value; Printing device.

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