JP2016163940A - Corrected applied voltage acquisition method, program and inkjet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a variation in ink discharge amounts on the basis of the difference in the concentration of ink in an inkjet printer having a head.SOLUTION: A method of acquiring a corrected applied voltage being an applied voltage to a head required for discharging a prescribed amount of ink in an inkjet printer having the head comprises: a step of acquiring first concentration-related information being concentration-related information on the first ink; a first test pattern formation step; a second test pattern formation step; a step of measuring the first color value of the first test pattern; a step of measuring the second color value of the second test pattern; a step of acquiring the applied voltage-color value relationship; a step of acquiring the target color value by using the color value-concentration-related information relationship in the test pattern formed by applying a prescribed voltage to a reference head; and a step of acquiring a corrected applied voltage on the basis of the target color value.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an inkjet printer.

  Conventionally, in a piezo ink jet printer, the magnitude of a voltage applied to a head is set so that ink having a desired ink weight is ejected from the head.

  Conventionally, a head is attached to a device for setting an applied voltage, a voltage is applied from the measuring device to the head, and the weight of ink droplets ejected from the head is measured with an electronic balance or the like to set the applied voltage. However, measuring the weight of ink droplets ejected from the head is time consuming and time consuming, and the work efficiency is poor. On the other hand, in order to improve the working efficiency, in the finished product of the ink jet printer, a test pattern is formed using a predetermined ink, and the weight of the ink droplet is derived based on the color information of the test pattern, and the applied voltage Has been proposed (see, for example, Patent Document 1).

JP 2005-246655 A

  Even if a constant applied voltage is applied to the head, the color value of the printed image differs if the ink density differs. When the ink lot is changed, the ink density (pigment density) may be different. When the driving voltage is set based on the color value in the method for setting the applied voltage in Patent Document 1, desired ink ejection is performed. In some cases, the amount was not enough. Therefore, a technique for suppressing variation in ink discharge amount based on a difference in ink density is provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, there is provided a method for obtaining a correction application voltage, which is an application voltage to the head necessary for the head to eject a predetermined amount of ink, in the ink jet printer including the head. Provided. The correction applied voltage acquisition method includes a step of acquiring first density-related information that is density-related information of the first ink, and a test pattern is formed by applying the first voltage to the head and ejecting the first ink. A first test pattern forming step, and a second test pattern forming step of forming a test pattern by applying a second voltage different from the first voltage to the head to eject the first ink. , Measuring a first color value that is a color value of the test pattern formed in the first test pattern forming step, and a color value of the test pattern formed in the second test pattern forming step. Using the first voltage, the second voltage, the first color value, and the second color value, a voltage applied to the head and the test pattern; A step of obtaining an applied voltage-color value relationship that is a relationship with a color value of a screen, and a color value of the test pattern formed by applying a predetermined voltage to a reference head having the same configuration as the previously obtained head A reference color value corresponding to the first density-related information is obtained using a color value-density-related information relationship that is a relationship between the density value and the density-related information, and based on the reference color value, the head The correction applied voltage is acquired using the step of acquiring a target color value that is a color value of the test pattern when a fixed amount of first ink is ejected, the applied voltage-color value relationship, and the target color value. And a step of performing.

  According to the correction application voltage acquisition method of this embodiment, the voltage (to be applied to the head) based on the target color value, which is the color value when a predetermined ink amount is ejected using the first ink and a test pattern is formed. Therefore, an appropriate applied voltage can be easily set as compared with the case where the corrected applied voltage is acquired by measuring the ink amount (weight). Further, since the target color value is determined based on the ink density of the first ink, it is possible to correct the variation in the ink discharge amount based on the variation in the ink density due to the difference in the ink lots. In addition, since the applied voltage-color value relationship is derived using an ink jet printer that is actually used, it is possible to correct variations in the ink ejection amount due to temporal changes in the piezo of the head.

(2) In the correction applied voltage acquisition method of the above aspect, the step of acquiring the color value-density related information relationship includes a step of acquiring second density related information that is density related information of the second ink, and the second A step of acquiring third density related information, which is density related information of a third ink having density related information different from the ink, and an applied voltage required for causing the reference head to eject the predetermined amount of the second ink. Obtaining a reference applied voltage, a third test pattern forming step of applying the reference applied voltage to the reference head to eject the second ink to form the test pattern, and applying the reference applied to the reference head. A fourth test pattern forming step of applying the applied voltage to eject the third ink to form the test pattern; and the third color which is a color value of the third test pattern A step of acquiring a saturation value; a step of acquiring a fourth color value which is a color value of the fourth test pattern; the third color value; the fourth color value; the second density-related information; And acquiring the color value-density related information relationship using 3 density related information. In this way, the color value-density related information relationship at a predetermined voltage can be easily acquired.

(3) In the correction applied voltage acquisition method of the above aspect, the target color value may be the reference color value. When the color value-density related information relationship is generated at an applied voltage at which a predetermined amount (target ink amount) of ink is ejected from the reference head, the target color value is set as the target color value. The value is the color value when a test pattern is formed by ejecting a predetermined amount (target ink amount) of first ink from the head to be used. Therefore, when the correction application voltage is acquired using the reference color value as the target color value, it is possible to acquire an application voltage in which the amount of the first ink ejected from the head is a predetermined amount (target ink amount).

(4) According to another aspect of the present invention, there is provided a program for causing an inkjet printer to realize the correction applied voltage acquisition method of the above aspect.

(5) According to another aspect of the present invention, an ink jet printer is provided. The ink jet printer includes a head for ejecting ink, test pattern data representing a test pattern, a color value of the test pattern formed by applying a predetermined voltage to a reference head having the same configuration as the head, and the ink. A storage unit for storing a color value-density-related information relationship that is a relationship with density-related information, and a test for controlling the head to form the test pattern on a medium based on the test pattern data A pattern forming unit; a color value measuring unit for measuring a color value of the test pattern; a voltage applied to the head when forming the test pattern; and a color of the test pattern measured in the color value measuring unit A voltage-color value relationship generation unit that generates an applied voltage-color value relationship representing a relationship between an applied voltage and a color value based on the value A reference color value corresponding to the first density related information that is the density related information of the first ink is acquired based on the color value-density related information relationship, and the reference color value and the voltage-color value relationship And an applied voltage setting unit that obtains a corrected applied voltage to be applied to the head such that the amount of the first ink ejected from the head is equal to the predetermined amount. According to this inkjet printer, since the color value measuring unit and the applied voltage setting unit are provided, the corrected applied voltage can be acquired based on the automatically measured color value in the inkjet printer.

  A plurality of constituent elements of each aspect of the present invention described above are not indispensable, and some or all of the effects described in the present specification are to be solved to solve part or all of the above-described problems. In order to achieve the above, it is possible to appropriately change, delete, replace with another new component, and partially delete the limited contents of some of the plurality of components. In order to solve part or all of the above-described problems or to achieve part or all of the effects described in this specification, technical features included in one embodiment of the present invention described above. A part or all of the technical features included in the other aspects of the present invention described above may be combined to form an independent form of the present invention.

  Note that the present invention can be realized in various modes. For example, the present invention can be realized in the form of a computer program for realizing the correction applied voltage acquisition method, a computer program for constructing an inkjet printer, a storage medium storing these programs, and the like. Examples of the storage medium include a flexible disk, HDD (Hard Disk Drive), CD-ROM (Compact Disk Read Only Memory), DVD (Digital Versatile Disk), Blu-ray (registered trademark) Disc, non-volatile disk, and the like. Various media that can be read by a computer, such as a memory card, an internal storage device of an image display device (semiconductor memory such as RAM or ROM), and an external storage device (USB (Universal Serial Bus) memory, etc.) can be used.

It is explanatory drawing which shows schematic structure of the inkjet printer 100 as 1st Embodiment of this invention. It is explanatory drawing which shows the planar structure of a white ink unit roughly. It is a block diagram which shows the structure of an inkjet printer. It is a figure which shows the light absorbency-color value table about white ink. It is the table | surface which showed the color value used for every ink color. It is process drawing which shows a light absorbency-color value table production | generation process. It is a table | surface which shows the parameter used in a light absorbency-color value table production | generation process and an applied voltage setting process. It is a schematic diagram which shows a test pattern typically. It is process drawing which shows an applied voltage setting process. It is a graph which shows the voltage-color value table of white ink. It is explanatory drawing for demonstrating acquisition of a target color value. It is explanatory drawing explaining acquisition of the target applied voltage using a voltage-color value table about white ink. It is explanatory drawing for demonstrating schematic structure of the printer system of 2nd Embodiment. It is the table | surface which showed the color value used for every dot size and ink color. It is a figure which shows the light absorbency-color value table in another reference | standard applied voltage.

A. First embodiment:
A1. Inkjet printer configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of an ink jet printer 100 as a first embodiment of the present invention. The ink jet printer 100 according to this embodiment is an ink jet type line printer that forms an image by ejecting ink droplets by a piezo method, and performs continuous printing while transporting a printing substrate 11 that is a belt-like recording medium in the longitudinal direction. Run. As the printing substrate 11, for example, glossy paper, coated paper, label paper, OHP film, or the like is used. In addition, as the printing substrate 11, plain paper, Japanese paper, inkjet paper, fabric, or the like may be used.

  The ink jet printer 100 mainly includes a control unit 10, a plurality of transport rollers 13, a base material feeding unit 20, a printing unit 30, a color value measuring unit 40, and a base material winding unit 50. . The control unit 10 is configured by a microcomputer including a CPU (Central Processing Unit) and a memory (main storage device), and can control each component of the inkjet printer 100. Specifically, the control unit 10 conveys the printing base material 11 in the inkjet printer 100, forms a print image in the printing unit 30, adjusts the ink discharge weight (setting of applied voltage), and colors by the color value measuring unit 40. Value measurement can be controlled.

  The plurality of transport rollers 13 constitute a transport path of the printing substrate 11 in the inkjet printer 100. Each transport roller 13 is appropriately disposed in the base material feeding unit 20, the printing unit 30, the color value measuring unit 40, and the base material winding unit 50. FIG. 1 illustrates an arrow PD that indicates the conveyance direction of the printing substrate 11 when a print image is formed. In this specification, the term “upstream” or “downstream” refers to the transport direction of the printing substrate 11 when a print image is formed (when ink droplets are ejected from the ink head).

  The substrate feeding unit 20 includes a substrate roller 21 on which the printing substrate 11 is wound in a roll shape. The substrate roller 21 is rotated by a motor (not shown) controlled by the control unit 10 and feeds the printing substrate 11 to the printing unit 30.

  The printing unit 30 includes a rotary drum 31, a plurality of ink head units, and a plurality of UV (ultraviolet) lamps. The ink head unit is filled with photocurable ink (so-called UV ink) that is cured by irradiation with UV. Ink droplets ejected from the ink head on the printing surface of the printing substrate 11 are cured by a UV lamp to form a printed image. The rotating drum 31 is rotated by a motor (not shown) controlled by the control unit 10 and transports the printing substrate 11 while supporting the printing substrate 11 on the circumferential side surface thereof.

  The printing unit 30 includes a white ink head unit 32W that discharges white ink, a cyan ink head unit 32C that discharges cyan ink, a magenta ink head unit 32M that discharges magenta ink, a yellow ink head unit 32Y that discharges yellow ink, and There are provided five types of ink heads, a black ink head unit 32K that discharges black ink. Hereinafter, when these ink heads are not distinguished, they are also simply referred to as ink head units 32. When an ink cartridge is attached to each ink head unit 32, ink is supplied to the ink head unit 32.

  FIG. 2 is an explanatory diagram schematically showing a planar configuration of the white ink head unit 32W. In FIG. 2, a surface facing the printing substrate 11 is illustrated. As shown in the figure, the white ink head unit 32W is a so-called line head unit that includes first to seventh white ink heads 321W to 327W, and each white ink head is arranged in two rows in a staggered pattern. is there. As illustrated, the first white ink head 321W includes a plurality of nozzles Nz. In the present embodiment, the first white ink head 321W includes 600 nozzles Nz. In order to clearly illustrate the nozzles, in FIG. 2, the number of nozzles is reduced and the size of the nozzles is increased. It is shown in the figure. Moreover, the code | symbol was attached | subjected only to one nozzle Nz, and illustration of the code | symbol was abbreviate | omitted about the other nozzle Nz. The second to seventh white ink heads 322W to 327W have the same configuration as the first white ink head 321W. Hereinafter, when the first to seventh white ink heads 321W to 327W are not distinguished, they are also simply referred to as white ink heads 320W. In the inkjet printer 100 of the present embodiment, the white ink head unit 32W has a length in a direction orthogonal to the conveyance direction of the printing base material 11 (indicated by an arrow PD in FIG. 2) substantially equal to the width of the printing base material 11. Match. The cyan ink head unit 32C, the magenta ink head unit 32M, the yellow ink head unit 32Y, and the black ink head unit 32K have the same configuration as the white ink head unit 32W. Hereinafter, when the ink head units 32 are not distinguished, the ink heads included in the ink head units 32 are also simply referred to as ink heads 320.

  Each nozzle Nz is provided with a piezo element which is one of electrostrictive elements and excellent in responsiveness. The piezo element is installed at a position in contact with an ink passage that guides ink to the nozzle Nz. As is well known, a piezo element is an element that transforms an electro-mechanical energy at a very high speed because its crystal structure is distorted by application of a voltage. In the present embodiment, by applying a predetermined voltage between the electrodes provided at both ends of the piezo element, one side wall of the ink passage is deformed to discharge a predetermined amount of ink droplets from the tip of the nozzle Nz. In the inkjet printer 100 of the present embodiment, the ink head unit 32 includes a plurality of ink heads 320. In the inkjet printer 100, in the design stage, a target value of ink amount ejected from one ink head 320 (hereinafter referred to as “target ink amount”) for each color and a target ink amount from the ink head 320 in advance. A voltage (hereinafter referred to as “initial applied voltage”) to be applied to each piezo element for discharging the ink droplets is set. For example, in the first to seventh white ink heads 321W to 327W included in the white ink head unit 32W, the same value (reference application voltage V0w described later) is set as the initial application voltage. In the design stage, although the initial applied voltage is set using an ink jet printer of the same type as the ink jet printer 100, the initial applied voltage VOw determined in the design stage is set to each white ink head 320W due to individual differences of the ink heads 320. Even if it is applied, the amount of ink ejected from each white ink head 320 may not be the target ink amount I0w. Also, as in the prior art, a method for forming a test pattern using a predetermined ink, deriving the weight of the ink droplet based on the color information of the test pattern, and setting a correction application voltage that becomes the target ink amount I0w In this case, the ink concentration (pigment concentration) may differ when the ink lot (manufacturing lot) is changed between when the initial applied voltage that is the target ink amount is set and when the correction applied voltage is set. Yes, even if the correction application voltage is applied, the target ink amount I0w may not be obtained. In the ink jet printer 100 according to the present embodiment, even when the ink lot is different between when the initial applied voltage that is the target ink amount is set and when the correction applied voltage is set, the ink jet printer 100 depends on the density of the white ink to be used. Thus, the voltage applied to each white ink head 320 can be corrected for each white ink head 320 so that the amount of ink ejected from each white ink head 320W becomes the target ink amount I0w. In the present embodiment, corrected voltages corresponding to the first to seventh white ink heads 321W to 327W are applied. In the white ink head unit 32W, the corrected voltage that is individually applied to each white ink head 320W is referred to as a white ink head correction application voltage Vhw. Similarly, the other ink head units 32 are also referred to as cyan ink head correction application voltage Vhc, magenta ink head correction application voltage Vhm, yellow ink head correction application voltage Vhy, and black ink head correction application voltage Vhk. When the ink colors are not distinguished, they are referred to as a correction application voltage Vh.

  The printing unit 30 includes one UV lamp downstream of each ink head unit 32. Specifically, the first main curing lamp 331, the first pinning lamp 332 downstream of the cyan ink head unit 32C downstream of the white ink head unit 32W, and the second pinning lamp 333 downstream of the magenta ink head unit 32M. A third pinning lamp 334 is disposed downstream of the head unit 32Y, and a second main curing lamp 335 is disposed downstream of the black ink head unit 32K. The pinning lamp is a UV lamp whose irradiation intensity is weaker than that of the main curing lamp, and suppresses ink bleeding and suppresses landing interference. Hereinafter, when these lamps are not distinguished, they are also simply referred to as UV lamps 33. The UV lamp 33 is controlled by the control unit 10 to switch ON / OFF and irradiation intensity.

  The color value measuring unit 40 includes a colorimeter 41. In the present embodiment, the colorimeter 41 measures the color of a test pattern, which will be described later, by a spectrocolorimetric method, and uses the CIE 1976 (L * a * b *) color system (hereinafter also simply referred to as CIELAB color system). Output the used color value. This LAB color system is based on three indicators: L * value representing lightness, a * value representing the degree of red or green (RG chroma), and b * value representing the degree of yellow or blue (YB chroma). To express. The colorimeter 41 can scan in a direction substantially orthogonal to the conveyance direction (arrow PD) of the printing substrate 11. The colorimeter is not limited to this embodiment. For example, colorimetry may be performed by a stimulus value direct reading method. Also, color values using other color systems such as LCH, CIE L * u * v *, HSI, etc. may be output. In the present embodiment, the color value measuring unit 40 measures the color value of the test pattern in an applied voltage setting process described later, and does not measure the color value during other normal printing.

  The substrate winding unit 50 includes a winding roller 51 that is rotationally driven by a motor (not shown) controlled by the control unit 10. The winding roller 51 winds up the printing substrate 11 fed from the color value measuring unit 40.

  FIG. 3 is a block diagram showing the configuration of the ink jet printer. The ink jet printer 100 includes a control unit 10, a substrate feeding unit 20, a printing unit 30, a color value measuring unit 40, a substrate winding unit 50, an image processing unit 60, and an external I / F unit 70. And an operation panel 80. Each of these elements is connected by a bus.

  The control unit 10 includes a CPU 120 and a memory 140. The memory 140 stores in advance test pattern data 142 that is image data representing a test pattern formed in an applied voltage setting process, which will be described later, and an absorbance-color value table 144 used in the applied voltage setting process.

  FIG. 4 is a diagram showing an absorbance-color value table for white ink. The absorbance-color value table 144 is generated in advance for each ink color in the design stage (generation of the absorbance-color value table will be described in detail later). That is, for each ink color, white ink absorbance-color value table 144W, cyan ink absorbance-color value table 144C, magenta ink absorbance-color value table 144M, yellow ink absorbance-color value table 144Y, black ink absorbance-color value table 144K. Are generated respectively. The absorbance-color value table 144 shows the relationship between the absorbance (hereinafter also referred to as “Abs”) and the color value at the applied voltage V0 that discharges the target ink amount I0. Since the absorbance is proportional to the ink density (pigment density), in this embodiment, the absorbance is used as information indicating the ink density. The information indicating the ink density is not limited to the absorbance, and various information indicating a correlation with the ink density such as conductivity, light reflectance, and transmittance can be used.

  As shown in FIG. 4, the L * value is used as the color value for the white ink. The color value when a predetermined image is formed (printed) with a constant applied voltage is proportional to the ink density. The degree of strength of the correlation between the ink density and the color value varies depending on the combination of the ink color and the color value. For this reason, it is desirable to use a combination in which the correlation is more prominent. For example, the combination of white, black and L * values, that is, lightness, shows a significant correlation, but the combination of yellow, magenta and L * values shows little correlation. Therefore, in the present embodiment, the absorbance-color value table 144 is generated using the color value corresponding to the ink color. As described above, in the inkjet printer 100, the applied voltage is set based on the color value. The combination of ink color and color value is the same in setting the applied voltage described later.

  FIG. 5 is a table showing color values used for each ink color. In the present embodiment, as shown in FIG. 5, color values corresponding to ink colors are used. That is, L * is used as the color value when the ink colors are white, cyan, and black, and b * is used as the color value when magenta and yellow. Although FIG. 4 shows the absorbance-color value table 144W for white ink, the other ink colors also have the same proportional relationship in the corresponding color values. The absorbance-color value table 144 in this embodiment corresponds to the color value-density-related information relationship in the claims.

  Further, the memory 140 stores a voltage-color value table 146 created in an applied voltage setting process described later. The CPU 120 functions as an applied voltage setting unit 122, a test pattern forming unit 124, and a voltage-color value table generating unit 126 according to a program stored in the memory 140. The voltage-color value table 146 in the present embodiment corresponds to the color value-density related information relationship in the claims.

  The operation panel 80 includes a display panel including an LCD for displaying menus and images, a cross button for operating the menus, a print instruction button, and the like (not shown). The external I / F unit 70 is an I / F for communicating with an external device such as a digital camera, a computer, or a USB device. The image processing unit 106 is a processor dedicated to image processing for generating print image data suitable for printing based on image data acquired through the external I / F unit 70.

  In this embodiment, the ink is stored in the ink cartridge 400 (FIG. 3), and the ink is supplied to each ink head 320 when the ink cartridge 400 is attached to the ink head unit 32. The ink cartridge 400 includes an IC (Integrated Circuit) chip on which manufacturing information including an identification number, the absorbance of the stored ink, the date of manufacture, the manufacturing location (manufacturing line name), and the like is described.

A2. Absorbance-color value table generation processing:
FIG. 6 is a process diagram showing an absorbance-color value table generation process. As described above, the absorbance-color value table 144 is generated at the design stage, and is stored in the memory 140 in advance when the inkjet printer 100 is manufactured. The absorbance-color value table 144 uses an ink jet printer (hereinafter also referred to as “reference printer”) including an ink head (hereinafter also referred to as “reference head”) having the same configuration as the ink head 320 of the ink jet printer 100. Then, a test pattern to be described later is printed, and weighed and measured for color values. Since the reference printer has the same configuration as that of the inkjet printer 100, the following description will be made using the same reference numerals as those assigned to the respective configurations of the inkjet printer 100.

  FIG. 7 is a table showing parameters used in the absorbance-color value table generation process and the applied voltage setting process described later. In the absorbance-color value table generation process and the applied voltage setting process described later, a description will be given with reference to FIG.

  The designer connects a computer for generating an absorbance-color value table (not shown; hereinafter referred to as a table generating computer) to the reference printer via the external I / F unit 70 of the reference printer, and generates the table. The computer is operated to control the reference printer, and an absorbance-color value table is generated. In the present embodiment, an absorbance-color value table is generated using the first reference ink and the second reference ink having the same color and different densities. First, the table generation computer acquires the absorbance Abs01 of the first reference ink from the ink cartridge 400 for each ink color (step S202). Specifically, the absorbance Abs01w of the first reference white ink, the absorbance Abs01c of the first reference cyan ink, the absorbance Abs01m of the first reference magenta ink, the absorbance Abs01y of the first reference yellow ink, and the absorbance Abs01k of the first reference black ink. get. Similarly, the absorbance Abs02 of the second reference ink is acquired from the ink cartridge 400 for each ink color (step S204). In this embodiment, the designer inputs the absorbance Abs01 and absorbance Abs02 described in the ink cartridge into the table generation computer. The table generation computer may be configured to automatically acquire the absorbance Abs01 and the absorbance Abs02 from the IC chip of the ink cartridge 400 mounted on the printing unit 30. The first reference ink in this embodiment corresponds to the second ink in the claims, the absorbance Abs01 corresponds to the second density-related information in the claims, and the second reference ink corresponds to the third ink in the claims. The absorbance Abs02 corresponds to the third concentration related information.

  Next, the table generation computer uses an application voltage (hereinafter referred to as “reference application voltage”) required to eject the target ink amount I0 (pl) (FIG. 7) using the first reference ink for each ink color. (Step S206). The target ink amount I0 is determined in advance. The designer uses the reference printer to change the applied voltage to a plurality of values, eject ink, weigh each of the ejected weights, and apply the applied voltage when ejecting the ink weight corresponding to the target ink amount I0 To get. The designer uses the average applied voltage when ejecting the ink weight corresponding to the target ink amount I0 acquired for each of the first to seventh white heads 321 as the reference applied voltage V0 (FIG. 7), and generates the table. To enter. The target ink amount I0 in the present embodiment corresponds to a predetermined amount in the claims.

  The table generation computer controls the printing unit 30 of the reference printer, applies the reference application voltage V0 to the ink head using the first reference ink of each color, and applies the test pattern data 142 stored in the memory 140 to the test pattern data 142. Based on this, a test pattern (first reference test pattern) is formed (step S208).

  FIG. 8 is a schematic diagram schematically showing a test pattern. When the printing base material 11 is conveyed while applying the reference application voltage V0 corresponding to each ink color to each ink head 320, a test pattern TP as shown in FIG. 8 is formed. The test pattern TP includes an ink region (hereinafter also referred to as “patch”) from which ink is ejected corresponding to each ink head 320. Specifically, the test pattern TP includes a first white patch W1 formed by the first white ink head 321W, a second white patch formed by the second white ink head 322W,..., A seventh white ink head. A seventh white patch W7 formed of 327W is provided. The first to seventh white patches W1 to W7 are formed with a space therebetween. As shown in FIG. 2, in the white ink head unit 32 </ b> W, each white ink head 320 </ b> W is arranged with an overlapping area OA that overlaps in a direction substantially orthogonal to the conveyance direction of the printing substrate 11. When the test pattern TP is formed, each ink head 320 is controlled so that white ink is not ejected from the overlapping area OA. Thereby, an interval between the patches in the first test pattern TP is formed. In the first white ink head 321W and the seventh white ink head 327W disposed at the end of the white ink head unit 32W in the direction substantially orthogonal to the conveyance direction PD, the first white ink head 321W and the seventh white ink head 327W also have the first area from the area EA having the same area as the overlapping area OA. Control is performed so that white ink is not ejected when one test pattern TP is formed. Thereby, the areas of the first to seventh white patches W1 to W7 can be made uniform.

  Similarly, the test patterns TP are the first to seventh cyan patches C1 to 7 formed by the first to seventh cyan ink heads 321C to 327C, and the first to seventh magenta ink heads 321M to 327M. Magenta patches M1-7, 1st-7th yellow patches Y1-7 formed by 1st-7th yellow ink heads 321Y-327Y, 1st-7th black patches formed by 1st-7th black ink heads 321K-327K K1-7 are provided.

  The table generating computer controls the color value measuring unit 40 to measure the color value L * a * b * 01 of each patch of the first reference test pattern formed in step S208 (step S210). The color value L * a * b * 01 is the color value (reference ink target color value) when the target ink amount I0 is reached when the first reference ink is used. That is, in the inkjet printer 100, when a test pattern is formed by ejecting the target ink amount I0 using the first reference ink and the color value is measured, L * a * b * 01 is obtained. As shown in FIG. 7, the reference ink target color values for each ink color are (white ink) L * 0w, (cyan ink) L * 0c, (magenta ink) b * 0m, (yellow ink) b * 0y, (Black ink) L * 0k. In the present embodiment, the colorimeter 41 measures a plurality of color values for one patch. The color value measurement result by the colorimeter 41 is stored in a memory (not shown) of a table generating computer. The colorimeter 41 scans substantially orthogonally to the conveyance direction of the printing substrate 11 to measure the color values of the first to seventh white patches W1 to W7, and then conveys the printing substrate 11. The measurement point of the patch is shifted, and the colorimeter 41 scans again to measure the color values of the first to seventh white patches W1 to W7. In this way, the scanning and measurement of the colorimeter 41 and the conveyance of the printing substrate 11 are repeated, and the color values of all the patches of the first test pattern TP are measured. In this embodiment, six points are measured for each patch. The color value L * a * b * 01 in the present embodiment corresponds to the third color value in the claims.

  Similarly, the table generating computer applies the reference application voltage V0 to the ink head using the second reference ink of each color to form a test pattern (second reference test pattern) (step S212). The color value L * a * b * 02 of each patch of the reference test pattern is measured in the same manner as described above (step S214). The color value L * a * b * 02 in the present embodiment corresponds to the fourth color value in the claims.

The table generation computer generates the absorbance-color value table 144 using Abs01, Abs02, L * a * b * 01, and L * a * b * 02 (step S216). For example, the white ink absorbance-color value table 144W (FIG. 4) will be described. The table generating computer extracts L * 01w from the color values L * 01w, a * 01w, and b * 01w measured for the white patches W1 to 7 of the first reference test pattern, and calculates the average value thereof. To do. Similarly, for the second reference test pattern, L * 02w is extracted and an average value is calculated. Using the average value of Abs01, Abs02, and L * 01w, and the average value of L * 02w, an absorbance-color value table 144W (FIG. 4) is generated. Similarly, the table generation computer generates the absorbance-color value table 144 using the color values (FIG. 5) corresponding to the respective ink colors. The generated absorbance-color value table 144 is stored in the memory 140 when the inkjet printer 100 is manufactured. The absorbance-color value table 144 is stored as a relational expression between absorbance and color value. Further, when the inkjet printer 100 is manufactured, the reference applied voltage V0 as the initial voltage and the reference ink target color value L * a * b * 0 as the initial target color value are stored in the memory 140, respectively. That is, after assembling the inkjet printer 100, the reference applied voltage V0 is applied to each ink head 320 until an applied voltage setting process described later is executed.
In this embodiment, in order to acquire the reference applied voltage V0 and the absorbance-color value table 144, ink is ejected using each ink head 320 of the reference printer, and the average value is calculated to calculate the reference applied voltage V0. Although the absorbance-color value table 144 is acquired, the reference applied voltage V0 and the absorbance-color value table 144 may be acquired using at least one ink head 320 for each color.

A3. Applied voltage setting process:
A method for setting the voltage applied to the ink head 320 will be described with reference to FIGS. FIG. 9 is a process diagram showing an applied voltage setting process. In the present embodiment, the applied voltage setting process is executed after the inkjet printer 100 is installed in the user's factory or the like. Hereinafter, the ink used when the applied voltage setting process is executed is referred to as “current ink”. The applied voltage setting process may be executed when the lot of ink filled in the ink head 320 of the inkjet printer 100 is changed. When the ink lot is changed, the changed ink corresponds to the “current ink”. The current ink in this embodiment corresponds to the first ink in the claims.

  When a seller (serviceman) or a user of the inkjet printer 100 instructs correction (setting) of the applied voltage via the operation panel 80 of the inkjet printer 100, the control unit 10 starts an applied voltage setting process. The applied voltage setting unit 122 acquires the absorbance Abs1 of the current ink from each color ink cartridge 400 (step S102 in FIG. 9). The test pattern forming unit 124 causes each ink head unit 32 to apply the first test voltage V1 for each color and print the first test pattern based on the test pattern data 142 (step S104 in FIG. 9). . The first test pattern is the same as the test pattern TP (FIG. 8) formed in the absorbance-color value table generation process described above. The absorbance Abs1 in the present embodiment corresponds to the first concentration related information in the claims, and the first test voltage V1 corresponds to the first voltage in the claims.

  When the first test pattern TP is transported to the color value measuring unit 40, the control unit 10 scans the colorimeter 41 in a direction substantially orthogonal to the transport direction PD, and the color of each patch of the first test pattern TP. The value L * a * b * 1 is measured (step S106 in FIG. 9). In the present embodiment, the colorimeter 41 measures six color values for one patch, similarly to the colorimetry in the above-described absorbance-color value table generation process. The average value of the measurement results of the six color values is used as the color value of one patch. The color value measurement result by the colorimeter 41 is stored in the memory 140. The color value L * a * b * 1 in the present embodiment corresponds to the first color value in the claims.

  Next, the test pattern forming unit 124 causes each ink head unit 32 to apply the second test voltage V2 for each color and print the second test pattern (step S108). The second test voltage V2 is set to a value different from the first test voltage V1. The second test pattern is also the same test pattern as the first test pattern. The second test voltage V2 in the present embodiment corresponds to the second voltage in the claims.

  When the second test pattern is conveyed to the color value measuring unit 40, the control unit 10 uses the colorimeter 41 to measure each patch of the second test pattern in the same manner as the color value measurement of the first test pattern TP described above. The color value L * a * b * 2 is measured (step S110). The color value measurement result by the colorimeter 41 is stored in the memory 140. The color value L * a * b * 2 in the present embodiment corresponds to the second color value in the claims.

  The voltage-color value table generation unit 126 creates a voltage-color value table 146 indicating the relationship between the applied voltage and the color value for each color and each ink head 320 based on the color value of each patch stored in steps S106 and S110. And stored in the memory 140 (step S112). The voltage-color value table 146 is stored as a relational expression between voltage and color value.

  The voltage-color value table 146 is generated using a color value corresponding to each ink color. The combination of the ink color and the color value is the same as that in the absorbance-color value table 144 described above. That is, when the ink colors are white, cyan, and black, L * is used as the color value, and when the ink color is magenta and yellow, b * is used as the color value (FIG. 5).

  FIG. 10 is a graph showing a voltage-color value table of a certain white ink head 320W that discharges white ink. The color value of the patch of the first test pattern when the first test voltage V1w is applied to the white ink head 320W is L * 1w, and the patch of the second test pattern when the second test voltage V2w is applied to the white ink head 320W The color value of L * 2w. Since it is well known that the relationship between the applied voltage and the color value L * a * b * is linear, the relationship between the applied voltage and the color value can be linearly approximated (FIG. 10). Similarly, a voltage-color value table 146 corresponding to each ink head 320 is generated for each ink color.

  FIG. 11 is an explanatory diagram for explaining acquisition of a target color value. The absorbance-color value table 144 shown in FIG. 11 is generated in the above-described absorbance-color value table generation process, and is stored in the memory 140. The applied voltage setting unit 122 uses the absorbance-color value table 144 shown in FIG. 11 to eject an ink droplet of the target ink amount I0 using the current ink based on the absorbance Abs1 of the current ink acquired in step S102. The target color value tL * a * b *, which is the color value of the test pattern generated in this way, is acquired (FIG. 9: Step S114). For example, for white current ink, the color value L * corresponding to the absorbance Abs1w of the current ink becomes the target color value tL * w using the white ink absorbance-color value table 144W (FIG. 4). Similarly, with respect to the other ink colors, the target color values tL * c (cyan), tb * m (magenta), tb * y (yellow), tL are used using the absorbance-color value table 144 corresponding to each ink color. * Acquire k (black).

  FIG. 12 is an explanatory diagram for explaining acquisition of a target applied voltage using a voltage-color value table for white ink. The applied voltage setting unit 122 uses the voltage-color value table 146 created in step S112 and stored in the memory 140 to use the corrected applied voltage Vh that is an applied voltage for obtaining the target color value tL * a * b *. (FIG. 9: Step S116). For example, since the target color value of the white ink head 320 is tL * w, as shown in FIG. 12, the white ink head 320 corresponding to the target color value tL * w is used using the voltage-color value table 146W. A corrected applied voltage Vhw is derived for each. Similarly, for other ink colors, a correction application voltage is derived for each ink head 320. The applied voltage setting unit 122 stores (sets) the derived corrected applied voltage Vh in the memory 140. When performing normal printing, the control unit 10 adjusts the voltage applied to each ink head 320 so that the correction applied voltage Vh for each ink head 320 set in the applied voltage setting process is set. As described above, the absorbance-color value table 144 shows the relationship between the absorbance and the color value at the voltage at which the ink droplet of the target ink amount I0 is ejected from the reference head. Therefore, the color value (target color value tL * a * b *) corresponding to the absorbance Abs1 of the current ink obtained by using the absorbance-color value table 144 is the ink value of the target ink amount I0 using the current ink. This corresponds to the color value of the test pattern generated by ejection. Therefore, when ink is ejected from each ink head 320 at the correction applied voltage Vh set based on the target color value tL * a * b *, the amount of ink ejected from each ink head 320 is set to the target ink amount I0. Can be adjusted. The target color value tL * a * b * in the present embodiment corresponds to the target color value and the reference color value in the claims.

A4. Effects of the embodiment:
In the inkjet printer 100 of the present embodiment, a voltage-color value table 146 that represents the relationship between the applied voltage and the color value is generated, and the target color value tL * corresponding to the target ink amount is generated using the voltage-color value table 146. The applied voltage (corrected applied voltage) is set based on a * b *. Since the measurement of the color value is easier than the measurement of the ink weight, an appropriate applied voltage can be easily set.

  In the inkjet printer 100 of this embodiment, when setting the applied voltage, the target color value tL * a * b * corresponding to the target ink amount I0 is set based on the absorbance of the ink. Since the absorbance is proportional to the ink density (pigment density), setting the target color value tL * a * b * based on the ink absorbance sets the target color value tL * a * b * corresponding to the ink density. can do. That is, in the inkjet printer 100 of the present embodiment, when setting the applied voltage based on the target color value, the target color value is corrected based on the ink density, and the corrected target color value tL * a * b. The applied voltage (corrected applied voltage) is set based on *. Specifically, in this embodiment, the reference ink target color value tL * a * b * 0 (FIG. 7) is set as an initial value of the target color value, and the ink density of the current ink is set in the applied voltage setting process. Based on the above, the target color value is corrected to the target color value tL * a * b *. As a result, an applied voltage can be set according to the ink density. Since the density of ink may vary from lot to lot, for example, the initial applied voltage is different when the initial lot of ink is different between when the initial applied voltage at which the target ink amount I0 is set and when the corrected applied voltage is set. Even if the correction application voltage is set based on the color value obtained by ejecting ink droplets by applying the ink to the head, the target ink amount may not be achieved. In contrast, in the inkjet printer 100 according to the present embodiment, the applied voltage setting process is performed using the target color value obtained by correcting the reference ink target color value according to the ink density used when the applied voltage setting process is performed. Thereby, the applied voltage according to the ink density can be set. For this reason, it is possible to correct the variation in the ink discharge amount based on the ink density which differs from lot to lot. As a result, bleeding, unevenness, etc. of the printed image can be suppressed. In the inkjet printer 100 according to the present embodiment, the target color value is changed according to the ink density. However, since the variation in the ink density is small and the change in the color value is small, when the printed image is viewed, The difference in color value is a level that humans cannot recognize.

  In addition, since the voltage-color value table 146 used when setting the applied voltage is created in the applied voltage setting process, the ink discharge amount accompanying the change in the relationship between the applied voltage and the ink discharge amount due to the aging of the piezo. Can be corrected.

B. Second embodiment:
FIG. 13 is an explanatory diagram for explaining a schematic configuration of a printer system according to the second embodiment. The printer system 1000 according to the second embodiment includes an inkjet printer 100A, a voltage setting computer 200, and a server 300. The printer system 1000 performs the applied voltage setting process described above.

  The ink jet printer 100 </ b> A includes a CPU 10, a substrate feeding unit 20, a printing unit 30, a memory 40, a substrate winding unit 50, an image processing unit 60, and an external I / F unit 70. Each of these elements is connected by a bus. The inkjet printer 100A does not include the applied voltage setting unit 122, the test pattern formation unit 124, and the voltage-color value table generation unit 126 in the inkjet printer 100 of the first embodiment. Further, the memory 40 of the ink jet printer 100A does not include the test pattern data 142, the absorbance-color value table 144, and the voltage-color value table 146 included in the memory 140 in the ink jet printer 100 of the first embodiment. The ink jet printer 100 </ b> A is connected to the voltage setting computer 200 via the external I / F unit 70.

  The voltage setting computer 200 includes a CPU 210, a memory 220, a display unit 230, and an external I / F unit 240. The CPU 210 functions as an applied voltage setting unit 212, a test pattern forming unit 214, and a voltage-color value table generating unit 216 in accordance with a program stored in the memory 220. The memory 220 stores in advance a test pattern data 222 that is image data representing a test pattern similar to the test pattern described in the first embodiment, and an absorbance-color value table 224 used in the applied voltage setting process. Yes. The memory 220 stores a voltage-color value table 226 created in the applied voltage setting process. The voltage setting computer 200 is connected to the server 300 via the Internet INT.

  The server 300 includes an absorbance database 310. In the absorbance database 310, manufacturing information of the ink cartridge 400 (cartridge identification number, absorbance of stored ink, date of manufacture, date of manufacture, manufacturing location (manufacturing line name), etc.) is described in association with each lot. The manufacturing information is described in the absorbance database 310 when the ink cartridge is manufactured.

  A seller (serviceman) of the ink jet printer 100A configures the printer system 1000 when the ink jet printer 100A is installed in a user's factory or the like, or when the ink head 320 is replaced due to deterioration with time, and the above-described printer system 1000 is configured. An applied voltage setting process is performed. The seller uses the voltage setting computer 200 to set the applied voltage of the ink jet printer 100A. Each step of the applied voltage setting process executed in the second embodiment is the same as the applied voltage setting step of the first embodiment, although the method of obtaining absorbance and the subject of each step are different, but the contents of the steps are the same. This will be described with reference to FIG. When the seller uses the voltage setting computer 200 to start the applied voltage setting process, the applied voltage setting unit 212 sets the identification number to the server 300 based on the identification number of the ink cartridge of the current ink. The corresponding absorbance is inquired, and the absorbance Abs1 of the current ink is acquired and stored in the memory 220 (FIG. 9: Step S102). The test pattern forming unit 214 controls the printing unit 30 of the ink jet printer 100 </ b> A to apply a first test voltage V <b> 1 for each color to each ink head 320 and perform a first test based on the test pattern data 222. The pattern is printed (FIG. 9: Step S104). When the first test pattern is conveyed to the color value measuring unit 40 of the ink jet printer 100A, the applied voltage setting unit 212 of the voltage setting computer 200 scans the colorimeter 41 in a direction substantially orthogonal to the conveyance direction PD. Similarly to the first embodiment, the color value L * a * b * 1 of each patch of the first test pattern TP is measured (FIG. 9: Step S106). In the present embodiment, the color value measurement result by the colorimeter 41 is stored in the memory 220 of the voltage setting computer 200.

  Next, the test pattern forming unit 214 of the voltage setting computer 200 similarly controls the printing unit 30 of the ink jet printer 100A to apply the second test voltage V2 to each ink head 320 for each color. Then, the second test pattern is printed (FIG. 9: Step S108). The second test voltage V2 is set to a value different from the first test voltage V1. The second test pattern is also the same test pattern as the first test pattern.

  When the second test pattern is conveyed to the color value measuring unit 40, the applied voltage setting unit 212 of the voltage setting computer 200 uses the colorimeter 41 to perform the first measurement similarly to the color value measurement of the first test pattern. The color value L * a * b * 2 of each patch of the two test patterns is measured (step S110). The color value measurement result by the colorimeter 41 is stored in the memory 220 of the voltage setting computer 200.

  The voltage-color value table generation unit 216 of the voltage setting computer 200 indicates the relationship between the applied voltage and the color value based on the first test voltage V1, the second test voltage V2, and the color value stored in the memory 220. A voltage-color value table 226 is generated and stored in the memory 220 (FIG. 9: Step S112). Here, the average value is used as the color value, as in the first embodiment. The voltage-color value table 226 is stored as a relational expression between voltage and color value.

  The applied voltage setting unit 212 of the voltage setting computer 200 uses the absorbance-color value table 224 to generate an ink droplet of the target ink amount I0 using the current ink based on the absorbance Abs1 of the current ink acquired in step S102. The target color value tL * a * b *, which is the color value of the test pattern generated by ejection, is acquired (FIG. 9: Step S114). The applied voltage setting unit 212 uses the voltage-color value table 226 to acquire a corrected applied voltage Vh that is an applied voltage for obtaining the target color value tL * a * b * and sets it in the inkjet printer 100A (FIG. 9: Step S116).

  The printer system 1000 of the second embodiment has the same effects as those of the first embodiment. Further, in the printer system 1000, the program for setting the applied voltage, the image data, the table, and the like are provided in the voltage setting computer 200 and the ink jet printer 100A is not provided. Therefore, the configuration of the ink jet printer 100A is facilitated. Can contribute to cost reduction. In the voltage setting computer 200, a program for causing the CPU 210 to function as the applied voltage setting unit 212, the test pattern forming unit 214, and the voltage-color value table generating unit 216, and test pattern data 222 stored in the memory 220. The absorbance-color value table 224 and the like may be downloaded to a general-purpose computer from the website of the manufacturer of the inkjet printer 100A via the Internet INT. Moreover, you may provide as a recording medium with which the said program and data were described.

C. Variations:
In addition, this invention is not restricted to said embodiment, In the range which does not deviate from the summary, it can be implemented in a various aspect, For example, the following deformation | transformation is also possible.

  (1) The number of heads, the number of nozzles, the number of ink colors, and the type of ink color are not limited to the above embodiment. For example, in the above-described embodiment, an inkjet printer including a plurality of line head units including a plurality of heads for one color of ink is illustrated. However, a configuration including one head for one color of ink may be used. Even in such a configuration, by setting the applied voltage as described in the above-described embodiment, the ink lot can be changed between when the initial applied voltage as the target ink amount is set and when the corrected applied voltage is set. Even if they are different, it is possible to correct the variation in the ink discharge amount. Further, for example, the ink color may include only black ink. Further, a configuration including light cyan and light magenta may be used.

  (2) In the above-described embodiment, the configuration in which the inkjet printer 100 includes the color value measuring unit 40 is illustrated, but a configuration without the color value measuring unit 40 may be employed. When the color value measuring unit 40 is not provided, for example, a designer, a seller, or a user of the ink jet printer 100 performs color value measurement as described above for each of various test patterns printed by the ink jet printer 100. When the measured color values are input via the operation receiving unit, the control unit can set the applied voltage based on the input color values.

  (3) The configuration of the color value measuring unit 40 is not limited to the above embodiment. You may make it the structure provided with the colorimeter 41 of the same number as the number of the patches of one color with which a test pattern is provided. For example, in the above embodiment, since the test pattern includes seven patches for each color, the color value measurement unit 40 may include seven colorimeters 41 and be provided corresponding to each patch. In this way, since the color value of each patch can be measured without scanning the colorimeter 41, the time required for measuring the color value can be shortened.

  (4) The inkjet printer may be configured so that dots of a plurality of sizes can be formed by ink droplets ejected from the ink head 320. As described above, the degree of strength of the correlation between the ink discharge amount and the color value varies depending on the combination of the ink color and the color value. Further, the intensity varies depending on the dot size. Therefore, in the case of an inkjet printer capable of forming dots of a plurality of sizes, it is preferable to determine the color value used for the applied voltage setting process according to the ink color and the dot size. For example, when L size dots and S size dots can be formed, a combination of color values as shown in FIG. 14 may be used. FIG. 14 is a table showing color values used for each dot size and ink color. Since the applied voltage differs between forming an L size dot and forming an S size dot, an absorbance-color value table is prepared for each dot size, and in step S114 of the applied voltage setting process, the dot is set. A target color value tL * a * b * is derived for each size. In step S116, the applied voltage is derived based on the target color value tL * a * b * corresponding to the dot size, so that the applied voltage can be corrected for each dot size.

  (5) In the above embodiment, the configuration including the transport mechanism for transporting the printing base material 11 is illustrated, but the present invention is not limited to this. A configuration in which a transport mechanism for transporting the ink head unit 32 may be provided. You may make it the structure provided with both the conveyance mechanism which conveys the printing base material 11, and the conveyance mechanism which conveys the ink head unit 32. FIG.

  (6) In the above embodiment, an ink jet printer that performs printing using UV curable ink is exemplified, but the type of ink is not limited to the above embodiment. For example, thermosetting ink, evaporative drying ink, or the like can be used. As the ink curing unit, a heater, a warm air machine, a far infrared lamp, a blower (without heating), or the like can be used depending on the type of ink. Further, the platen may be heated.

  (7) In the above embodiment, the ink jet printer provided with the ink head 320 that ejects ink droplets using a piezo element is illustrated, but any other ink head that ejects an amount of ink according to the applied voltage may be used. Ink droplets may be ejected by a method.

  (8) In the above embodiment, in the reference printer, the absorbance-color value table 144 indicating the relationship between the absorbance and the color value at the reference applied voltage V0 that discharges the target ink amount is generated. It is not limited to the embodiment. For example, the relationship between absorbance and color value at other voltages may be shown. This is because the relationship (inclination) between the absorbance and the color value at a constant voltage is the same. When the application voltage setting process is executed using 144T indicating the relationship between the absorbance and the color value at another reference application voltage V0T different from the reference application voltage V0, in step S114 (FIG. 9), the target color value tL * a * b * is obtained as follows.

  FIG. 15 is a diagram showing an absorbance-color value table at other reference applied voltages. In FIG. 14, the absorbance-color value table 144T at the other reference applied voltage V0T is shown by a solid line, and the absorbance-color value table 144 at the reference applied voltage V0 is shown by a broken line. In the applied voltage setting process (FIG. 9), in step S114, the target color value tL * a * b * is acquired using the absorbance-color value table 144T (FIG. 15). At this time, based on the absorbance-color value table 144T, the color value corresponding to the absorbance Abs1 of the current ink (corresponding to the reference color value in the claims) and the color value corresponding to the absorbance Abs01 of the first reference ink. The difference ΔL * a * b is derived. The difference ΔL * a * b is added to the color value L * a * b * 01 (reference ink target color value) of the first reference ink at the reference applied voltage V0 to obtain the target color value tL * a * b *. As described above, since the relationship (inclination) between the absorbance and the color value at the constant voltage is the same, the color value L * which is the color value of the test pattern formed by ejecting the target ink amount using the first reference ink. This is because when the difference ΔL * a * b is added to a * b * 01, it matches the color value of the test pattern formed by ejecting the target ink amount using the current ink.

  (9) In the first embodiment, the designer generates the absorbance-color value table 144 using a table generation computer, but the present invention is not limited to this. The designer uses the operation panel of the reference printer to operate the reference printer to form a test pattern, and uses the same colorimeter as the colorimeter 41 for the color values of the formed test pattern patches. May be measured. That is, the designer may perform all the steps shown in FIG. Further, the inkjet printer 100 may include an absorbance-color value table generation unit, and the inkjet printer 100 may automatically execute all the steps except S206 of the step illustrated in FIG.

  (10) The order of the steps in the absorbance-color value table generation process and the applied voltage setting process is not limited to the above embodiment, and can be changed as appropriate.

(11) In the above embodiment, when the absorbance-color value table 144 and the voltage-color value table 146 are generated, an example of linear approximation using two points is shown, but three or more points may be used.
(12) In the above embodiment, the reference printer has the same configuration as that of the inkjet printer 100. However, the reference printer may not have the same configuration. The number of ink heads 320 for each color provided in the reference printer may be different from that of the inkjet printer 100.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 11 ... Printing base material 12 ... Control part 13 ... Conveyance roller 20 ... Base material feeding part 21 ... Base material roller 30 ... Printing part 31 ... Rotating drum 32 ... Ink head unit 32C ... Cyan ink head unit 32K ... Black ink head unit 32M ... Magenta ink head unit 32W ... White ink head unit 32Y ... Yellow ink head unit 40 ... Color value measuring unit 41 ... Colorimeter 50 ... Base material winding unit 51 ... Winding roller 100 ... Inkjet printer 320 ... Ink head 320C ... Cyan ink head 320K ... Black ink head 320M ... Magenta ink head 320W ... White ink head 320Y ... Yellow ink head 331 ... First main curing lamp 332 ... First pinning lamp 333 ... Second pinning lamp 334 ... Third pinning lamp 335 ... Second permanent curing lamp 336 ... Third permanent curing lamp C ... Cyan patch M ... Magenta patch Y ... Yellow patch V0 ... Reference applied voltage V1 ... First test voltage V2 ... Second test voltage Nz ... Nozzle

Claims (5)

In an inkjet printer provided with a head, the head obtains a correction application voltage that is an application voltage to the head that is necessary for the head to eject a predetermined amount of ink,
Obtaining first density related information which is density related information of the first ink;
A first test pattern forming step of forming a test pattern by applying a first voltage to the head and discharging the first ink;
A second test pattern forming step of forming a test pattern by applying a second voltage different from the first voltage to the head to eject the first ink;
Measuring a first color value that is a color value of the test pattern formed in the first test pattern forming step;
Measuring a second color value that is a color value of the test pattern formed in the second test pattern forming step;
Applied voltage-color value relationship that is a relationship between an applied voltage applied to the head and a color value of the test pattern using the first voltage, the second voltage, the first color value, and the second color value A process of obtaining
Using a color value-density-related information relationship, which is a relationship between the color value of the test pattern formed by applying a predetermined voltage to a reference head having the same configuration as the head and the density-related information, acquired in advance. , A reference color value corresponding to the first density related information is acquired, and the target color value of the test pattern when the head ejects the predetermined amount of the first ink using the reference color value Obtaining a color value;
Using the applied voltage-color value relationship and the target color value to obtain the corrected applied voltage;
A correction applied voltage acquisition method comprising: The correction applied voltage acquisition method according to claim 1,
The step of acquiring the color value-density related information relationship includes:
Obtaining second density related information which is density related information of the second ink;
Obtaining third density-related information that is density-related information of a third ink having density-related information different from that of the second ink;
Obtaining a reference applied voltage that is an applied voltage necessary for causing the reference head to eject the predetermined amount of the second ink;
A third test pattern forming step of forming the test pattern by applying the reference applied voltage to the reference head and discharging the second ink;
A fourth test pattern forming step of applying the reference applied voltage to the reference head and discharging the third ink to form the test pattern;
Obtaining the third color value which is a color value of the third test pattern;
Obtaining a fourth color value which is a color value of the fourth test pattern;
Obtaining the color value-density related information relationship using the third color value, the fourth color value, the second density related information, and the third density related information;
A correction applied voltage acquisition method comprising: The correction applied voltage acquisition method according to claim 1 or 2,
The correction applied voltage acquisition method, wherein the target color value is the reference color value.   The program which makes an inkjet printer implement | achieve the correction | amendment applied voltage acquisition method as described in any one of Claim 1- Claim 3. An inkjet printer,
A head for ejecting ink;
Test pattern data representing a test pattern, and a color value-density which is a relationship between a color value of the test pattern formed by applying a predetermined voltage to a reference head having the same configuration as the head and the density-related information of the ink A storage unit for storing related information relationships;
A test pattern forming unit that controls the head to form the test pattern on a medium based on the test pattern data;
A color value measuring unit for measuring the color value of the test pattern;
Applied voltage-color value representing the relationship between applied voltage and color value based on the voltage applied to the head when forming the test pattern and the color value of the test pattern measured by the color value measuring unit A voltage-color value relationship generation unit for generating a relationship;
Based on the color value-density-related information relationship, a reference color value corresponding to the first density-related information that is the density-related information of the first ink is acquired, and based on the reference color value and the voltage-color value relationship. An applied voltage setting unit that acquires a correction applied voltage to be applied to the head such that the amount of the first ink ejected from the head is equal to the predetermined amount;
An inkjet printer comprising:

Images