Calibration method, printing method and test pattern

Abstract

To solve the problem that there is a room for improvement in a conventional calibration method.SOLUTION: A calibration method is for correcting inter-machine differences between a plurality of printing devices. The plurality of printing devices respectively have a plurality of density settings including a standard density setting that is a standard density, with respect to a density of a printing agent that is attached to a printing medium. The calibration method includes the steps of: printing a standard density setting pattern on the printing medium with the standard density setting by one printing device; printing a density setting pattern for each of the plurality of density settings on a position adjacent to the standard density setting pattern of the printing medium by another printing device; and defining the density of the density setting pattern closest to the density of the standard density setting pattern of the plurality of density setting patterns as the standard density setting of the other printing device.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a calibration method, a printing method, and a test pattern. [Background technology]

[0002] Patent Document 1 discloses a technique for calibrating a printing device based on the results of printing a test pattern by the printing device on a reference sheet on which a reference pattern serving as a color sample is printed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-351261 A Summary of the Invention [Problem to be solved by the invention]

[0004] By printing the same content on multiple printing devices, the printing time required for multiple copies of the printed material can be reduced. In such cases, it is required to unify the color tones between the multiple printing devices. In the technology described in Patent Document 1, it is necessary to perform calibration for each device based on the results of a test pattern printed on a reference sheet prepared for each of the multiple printing devices. There is room for improvement in the conventional calibration method. [Means for solving the problem]

[0005] A calibration method for correcting machine differences among a plurality of printing devices that print on a printing medium with a printing agent by applying the printing agent to the printing medium, wherein each of the plurality of printing devices has a plurality of density settings for the density of the printing agent to be applied to the printing medium, including a standard density setting which is a standard density, and the calibration method includes printing a standard density setting pattern on the printing medium at the standard density setting by one of the plurality of printing devices, printing a density setting pattern for each of the plurality of density settings by another of the plurality of printing devices that is different from the one printing device, at a position adjacent to the standard density setting pattern on the printing medium, and updating the density of the density setting pattern among the plurality of density setting patterns that is closest to the density of the standard density setting pattern as the standard density setting of the other printing device.

[0006] A calibration method for correcting machine differences among a plurality of printing devices that print on a printing medium with a printing agent by adhering the printing agent to the printing medium, each of the plurality of printing devices having a plurality of density settings including a standard density setting which is a standard density for the density of the printing agent to be adhered to the printing medium, the calibration method including: printing a standard density setting pattern on the printing medium at the standard density setting by at least two of the printing devices of the plurality of printing devices; printing a density setting pattern for each of the plurality of density settings by another of the plurality of printing devices different from the printing device that printed the standard density setting pattern, at a position adjacent to the standard density setting pattern for each of the standard density setting patterns; and updating, in one of the combinations of one of the standard density setting patterns and a plurality of the density setting patterns adjacent to the one standard density setting pattern, the density of the density setting pattern among the plurality of density setting patterns which is closest to the density of the standard density setting pattern as the standard density setting of the other printing device.

[0007] A calibration method for correcting differences between a plurality of printing devices that print on a printing medium by applying a printing agent to the printing medium, the plurality of printing devices each having a plurality of density settings for the density of the printing agent to be applied to the printing medium, including a standard density setting that is a standard density, the calibration method comprising: printing a standard density setting pattern on the printing medium at the standard density setting by one of the plurality of printing devices; and printing a standard density setting pattern on the printing medium at a position adjacent to the standard density setting pattern by another of the plurality of printing devices that is different from the one printing device. the density setting pattern being printed for each of the plurality of density settings; a density determination being made to determine whether or not the plurality of density setting patterns include a density setting pattern that is close to the density of the standard density setting pattern; and, if the result of the density determination is "yes," updating the density of the density setting pattern that is close to the density of the standard density setting pattern as the standard density setting of the other printing device; and, if the result of the determination is "no," repeatedly printing the standard density setting pattern by the other printing device, printing the plurality of density setting patterns, and the density determination being performed until the result of the density determination is "yes."

[0008] The printing method is a printing method for printing on a printing medium with a printing agent by adhering the printing agent to the printing medium, and includes printing a standard density setting pattern on the printing medium at a standard density setting that is a standard density among the multiple density settings by a first printing device of a plurality of printing devices having multiple density settings for the density of the printing agent to be adhered to the printing medium, and printing a density setting pattern for each of the multiple density settings by a second printing device of the plurality of printing devices that is different from the first printing device at a position adjacent to the standard density setting pattern on the printing medium.

[0009] The test pattern is a test pattern printed on a printing medium with a printing agent by applying the printing agent to the printing medium, and includes a standard density setting pattern printed at a standard density setting, which is the standard density among the multiple density settings, by a first printing device among a plurality of printing devices having multiple density settings for the density of the printing agent to be applied to the printing medium, and a density setting pattern printed adjacent to the standard density setting pattern for each of the multiple density settings by a second printing device among the plurality of printing devices that is different from the first printing device. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a printing system. [Diagram 2] FIG. 1 is a block diagram illustrating a configuration of a printing apparatus. [Diagram 3] FIG. 4 is a diagram for explaining density setting data. [Figure 4] FIG. 4 is a diagram for explaining a standard density setting pattern. [Diagram 5] FIG. 4 is a diagram for explaining a graduated density pattern. [Figure 6] FIG. 4 is a diagram for explaining an example of a calibration test pattern. [Figure 7] FIG. 4 is a diagram for explaining the flow of a first calibration method. [Figure 8] FIG. 4 is a diagram for explaining an example of a calibration test pattern. [Figure 9] FIG. 11 is a diagram for explaining the flow of a second calibration method. [Figure 10] FIG. 4 is a diagram for explaining an example of a calibration test pattern. [Figure 11] FIG. 13 is a diagram illustrating another configuration of the printing system. [Figure 12] FIG. 11 is a diagram for explaining the flow of a third calibration method. [Figure 13] FIG. 4 is a diagram for explaining a standard density setting pattern. [Figure 14] FIG. 4 is a diagram for explaining an example of a calibration test pattern. [Figure 15]FIG. 4 is a diagram for explaining an example of a calibration test pattern. [Figure 16] FIG. 4 is a diagram for explaining an example of a calibration test pattern. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] As shown in FIG. 1, the printing system 1 includes multiple printing devices 2 and a computer 3. The printing devices 2 are inkjet printers that print images such as characters and photographs on a medium 4, such as paper, by ejecting ink, which is an example of a liquid, onto the medium 4 being transported. The ink is an example of a printing agent. The medium 4 is an example of a print medium. The printing device 2 includes an inkjet head 5 and a carriage 6. The inkjet head 5 performs printing by depositing ink on the medium 4. The carriage 6 moves the inkjet head 5 back and forth in the width direction of the medium 4.

[0012] The printing device 2 is a serial type that performs printing while moving the inkjet head 5 back and forth in the width direction of the medium 4. The printing device 2 also includes a transport motor, which will be described later. The transport motor generates power for transporting the medium 4. In the printing device 2, the inkjet head 5 ejects ink toward the medium 4 while moving the carriage 6 back and forth in the width direction of the medium 4, which is transported by the power of the transport motor. This causes printing to be performed on the medium 4 with ink. The inkjet head 5 may be configured as a line type that is provided across the width direction of the medium 4. In this embodiment, the printing system 1 has two printing devices 2 as the multiple printing devices 2. When identifying each of the two printing devices 2, they are referred to as a first printing device 2A and a second printing device 2B. The first printing device 2A is an example of a first printing device, and the second printing device 2B is an example of a second printing device.

[0013] The computer 3 supplies print data to the multiple printing devices 2. The computer 3 is, for example, a personal computer. The multiple printing devices 2 print on the medium 4 based on the print data received from the computer 3. The multiple printing devices 2 print on the medium 4 by depositing ink on the medium 4 based on the print data. The computer 3 and the multiple printing devices 2 are connected to each other so that they can communicate with each other. The connection between the computer 3 and the multiple printing devices 2 may be wired or wireless. The connection between the computer 3 and the multiple printing devices 2 may be communication via a network such as a LAN (Local Area Network).

[0014] As shown in FIG. 2, the printing device 2 includes a communication interface 11, a control unit 12, a memory 13, a drive signal generating circuit 14, a conveyance motor 15, and a carriage motor 16. In FIG. 2, the interface is denoted as I / F. The communication interface 11 is communicatively connected to an external device including a computer 3. The communication interface 11 communicates with the external device according to a predetermined communication protocol. The communication may be either wired or wireless. The communication interface 11 includes, for example, a connection port for wired communication, an antenna for wireless communication, and an interface circuit. The communication interface 11 receives print data from the computer 3. The communication interface 11 transmits various data to the computer 3. The communication interface 11 outputs the print data received from the computer 3 to the control unit 12.

[0015] The control unit 12 is a controller that controls the printing device 2. The control unit 12 performs overall control of the operation of the printing device 2 by executing a control program stored in the memory 13. The control unit 12 is a processor. For example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) can be used as the processor. The memory 13 is composed of a RAM (Random Access Memory), a ROM (Read Only Memory), etc. The RAM is used for temporary storage of various data, etc., and the ROM stores the control program for controlling the operation of the printing device 2, various setting data, etc.

[0016] The control unit 12 functions as various functional units by executing a control program stored in the memory 13. The control unit 12 includes a transport control unit 21, a carriage control unit 22, and a discharge control unit 23 as functional units. The control unit 12 functions as the transport control unit 21, the carriage control unit 22, and the discharge control unit 23 by executing a control program stored in the memory 13. The transport control unit 21 controls the drive of the transport motor 15. The transport motor 15 generates power for transporting the medium 4. The carriage control unit 22 controls the drive of the carriage motor 16. The carriage motor 16 generates power for reciprocating the carriage 6. The discharge control unit 23 controls the drive of the inkjet head 5.

[0017] The drive signal generating circuit 14 generates a drive signal to be applied to the drive element of the inkjet head 5. The inkjet head 5 has a plurality of nozzle holes (not shown). In the inkjet head 5, the drive element provided for each nozzle hole is driven to eject ink as ink droplets from each nozzle hole. The drive signal for driving the drive element of the inkjet head 5 has four types of drive pulses set for each drive period based on the printing resolution. The ink droplets ejected from the nozzle holes adhere to the medium 4 to form dots. The four types of drive pulses correspond to the size of the dots to be formed on the medium 4.

[0018] Ink droplets are ejected from the nozzle holes in sizes corresponding to four types of drive pulses. By selectively applying four types of drive pulses to the drive elements, dots of three sizes, large, medium, and small, can be formed. The four types of drive pulses also include a drive pulse that does not eject ink droplets. The drive signal, which sets the four types of drive pulses, allows the drive elements of the inkjet head 5 to control the ejection amount of four gradations for each drive cycle based on the printing resolution. In the printing device 2, the gradation of printing on the medium 4 is controlled based on the print data received from the computer 3.

[0019] The memory 13 stores density setting data 26, standard density setting pattern data 27, and graded density pattern data 28. As shown in FIG. 3, the density setting data 26 is data that specifies the density that is set in the printing device 2. The density setting data 26 is set for each machine of the printing device 2. In the density setting data 26, a density grade is set for each machine of the printing device 2. The density setting data 26 is data that specifies the density grade. In the example shown in FIG. 3, five grades from -2 to +2 are applied as density grades. Grade 0 density is the standard density. The standard density is the standard density for each machine of the printing device 2. Grade 0 density is set as the standard density setting for each machine of the printing device 2.

[0020] The density grades can be defined, for example, by the size of dots formed by the ink droplets described above. By defining the combination of dot sizes formed per unit area of ​​the medium 4, different densities can be set for each grade. The density grades based on dot size are standardized between multiple printing device 2 machines. In other words, for the same density grade, the combination of dot sizes per unit area of ​​the medium 4 is the same between multiple printing device 2 machines.

[0021] However, there are differences in the amount of ink droplets ejected between the multiple printing devices 2. Due to manufacturing tolerances, there are differences in the amount of ink droplets ejected between the multiple printing devices 2 even when the drive elements of the inkjet head 5 are driven with the same drive pulse. Therefore, even if the density grade is the same, there may be differences in density between the multiple printing devices 2. For this reason, the density is adjusted for each device based on a density sample at the manufacturing stage of the printing device 2. This makes it possible to keep the differences in density between the multiple printing devices 2 low at the manufacturing stage of the printing device 2. In other words, the variation in density of the same grade between the multiple printing devices 2 is kept low at the manufacturing stage of the printing device 2.

[0022] The density adjustment for each machine of the printing device 2 can be realized, for example, by adjusting the voltage value applied to the driving element of the inkjet head 5. In the inkjet head 5, the amount of ink droplets ejected from the nozzle hole can be changed according to the voltage value of the driving pulse applied to the driving element. By changing the voltage value of the driving pulse applied to the driving element, the driving amount of the driving element can be changed. As a result, in the inkjet head 5, the ejection amount of ink droplets ejected from the nozzle hole can be changed. By adjusting the voltage value of the driving pulse applied to the driving element of the inkjet head 5 for each machine of the printing device 2, the density can be adjusted for each machine. As a result, the machine difference in density of the same grade in multiple printing devices 2 can be kept low.

[0023] The density setting data 26 shown in Fig. 2 includes data that specifies density grades according to dot size, and data that specifies a voltage value that adjusts the density for each type of printer 2. The print data sent from the computer 3 to the printer 2 includes data that specifies the image, text, etc. to be printed, as well as data that specifies the density of the image, text, etc. When the printer 2 receives the print data from the computer 3, the control unit 12 reads the density setting data 26 from the memory 13. Based on the density setting data 26 read from the memory 13, the control unit 12 causes the inkjet head 5 to print on the medium 4 the image or text with the density specified in the print data.

[0024] The standard density setting pattern data 27 shown in FIG. 2 is data that defines a test printing pattern related to the density of ink to be applied to the medium 4. The standard density setting pattern data 27 defines a pattern with a standard density setting among the test printing patterns related to the density of ink. The standard density setting is the density setting at grade 0 shown in FIG. 3 described above. In other words, the standard density setting pattern data 27 defines a test printing pattern printed with the standard density setting. When the printing data sent from the computer 3 to the printing device 2 instructs test printing based on the standard density setting pattern data 27, the control unit 12 reads the standard density setting pattern data 27 from the memory 13. The control unit 12 causes the inkjet head 5 to print on the medium 4 based on the standard density setting pattern data 27 read from the memory 13.

[0025] FIG. 4 is a diagram for explaining the standard density setting pattern 31. The control unit 12 causes the standard density setting pattern 31 shown in FIG. 4 to be printed on the medium 4 based on the standard density setting pattern data 27. The standard density setting pattern 31 is a pattern printed on the medium 4 according to the standard density setting set for each machine of the printing device 2. The standard density setting pattern 31 is a ring-shaped pattern. In the standard density setting pattern 31, an area where ink is applied is formed in a ring shape. No ink is applied to the area inside the ring-shaped standard density setting pattern 31. In other words, the base material of the medium 4 is exposed in the area inside the ring-shaped standard density setting pattern 31. The area inside the ring-shaped standard density setting pattern 31 is called a blank area BL.

[0026] The graduated density pattern data 28 shown in FIG. 2 is data that defines a test printing pattern related to the density of ink to be applied to the medium 4. The graduated density pattern data 28 defines patterns for all grades defined in the density setting data 26 shown in FIG. 3 among the test printing patterns related to ink density. The graduated density pattern data 28 defines a test printing pattern to be printed in all grades of density defined in the density setting data 26. When the printing data sent from the computer 3 to the printing device 2 instructs test printing based on the graduated density pattern data 28, the control unit 12 reads the graduated density pattern data 28 from the memory 13. The control unit 12 causes the inkjet head 5 to print on the medium 4 based on the graduated density pattern data 28 read from the memory 13.

[0027] FIG. 5 is a diagram for explaining the stepped density pattern 32. The control unit 12 prints the stepped density pattern 32 shown in FIG. 5 on the medium 4 based on the stepped density pattern data 28. The stepped density pattern 32 is a pattern printed on the medium 4 by the density setting data 26 set for each machine of the printing device 2. As shown in FIG. 5, the stepped density pattern 32 is a pattern in which density setting patterns 33 for each density setting are successively arranged in stages. Among the multiple density setting patterns 33 in the stepped density pattern 32, the density setting pattern 33 by the standard density setting shown in FIG. 3 is identified as the density setting pattern 33A. The standard density setting shown in FIG. 3 is a density setting of grade 0. Therefore, the density setting pattern 33A shown in FIG. 5 is also the density setting pattern 33 by the density setting of grade 0.

[0028] Of the multiple density setting patterns 33 in the graduated density pattern 32 shown in Fig. 5, the density setting pattern 33 with a density setting of +1 grade is identified as density setting pattern 33B. Similarly, the density setting pattern 33 with a density setting of +2 grade is identified as density setting pattern 33C. The density setting pattern 33 with a density setting of -1 grade is identified as density setting pattern 33D. The density setting pattern 33 with a density setting of -2 grade is identified as density setting pattern 33E. The graduated density pattern 32 has a shape and size that fits into the blank area BL of the standard density setting pattern 31 shown in Fig. 4. The graduated density pattern 32 fits into the blank area BL of the standard density setting pattern 31 that is formed in a ring shape.

[0029] FIG. 6 is a diagram for explaining an example of the calibration test pattern 35. The calibration test pattern 35 is an example of a test pattern. As shown in FIG. 6, the calibration test pattern 35 is a test pattern in which a standard density setting pattern 31 and a graded density pattern 32 are printed on one medium 4. In the calibration test pattern 35, the standard density setting pattern 31 is printed by one of the printing apparatuses 2 of the first printing apparatus 2A and the second printing apparatus 2B shown in FIG. 1. In the calibration test pattern 35, the graded density pattern 32 is printed by the other printing apparatus 2 of the first printing apparatus 2A and the second printing apparatus 2B. That is, in the calibration test pattern 35, the standard density setting pattern 31 and the graded density pattern 32 are printed by different printing apparatuses 2.

[0030] For example, a case will be described where the standard density setting pattern 31 shown in FIG. 6 is printed by the first printing device 2A. In this case, the stepped density pattern 32 is printed by the second printing device 2B. The standard density setting pattern 31 printed by the first printing device 2A is identified as the standard density setting pattern 31A. Moreover, the stepped density pattern 32 printed by the second printing device 2B is identified as the stepped density pattern 32B. As described above, the stepped density pattern 32B is printed inside the standard density setting pattern 31A. In other words, the stepped density pattern 32B is located in the blank area BL of the standard density setting pattern 31A shown in FIG. 4.

[0031] 6, the stepped density pattern 32B is surrounded by the standard density setting pattern 31A. Therefore, the standard density setting pattern 31A and the stepped density pattern 32B are adjacent to each other. Note that the stepped density pattern 32 does not need to be surrounded by the standard density setting pattern 31 as long as the standard density setting pattern 31 and each of the multiple density setting patterns 33 of the stepped density pattern 32 are adjacent to each other.

[0032] The printing method of the calibration test pattern 35 includes printing a standard density setting pattern 31A on the medium 4 at a standard density setting by a first printing device 2A, which is one of the multiple printing devices 2. The printing method of the calibration test pattern 35 includes printing a density setting pattern 33 for each of a plurality of density settings by a second printing device 2B at a position adjacent to the standard density setting pattern 31A on the medium 4. The second printing device 2B is a printing device 2 different from the first printing device 2A, which is one of the multiple printing devices 2. The calibration test pattern 35 can be printed by this printing method. Note that in the printing method of the calibration test pattern 35, the printing of the standard density setting pattern 31 and the printing of the stepped density pattern 32 may be performed in either order.

[0033] In the example shown in FIG. 6, the density setting pattern 33 that is closest to the density of the standard density setting pattern 31A among the multiple density setting patterns 33 of the graded density pattern 32B is the density setting pattern 33D. The density setting pattern 33D is not the standard density setting. The density setting pattern 33D is a density setting of -1 grade. In other words, the density setting of -1 grade of the second printing device 2B is equivalent to the standard density setting of the first printing device 2A. Therefore, if the density of -1 grade of the second printing device 2B is updated as the standard density setting of the second printing device 2B, the density can be unified between the first printing device 2A and the second printing device 2B. The standard density setting of the printing device 2 is updated by updating the density setting data 26 shown in FIG. 2. In other words, when updating the standard density setting of the printing device 2, the updated density setting is overwritten on the density setting data 26 shown in FIG. 2.

[0034] Fig. 7 is a diagram illustrating the flow of the first calibration method. As shown in Fig. 7, the first calibration method includes steps S1, S2, and S3. Step S1 is a step in which one printing device 2 out of the multiple printing devices 2 prints a standard density setting pattern 31 on the medium 4 at the standard density setting. In other words, step S1 is a step in which the first printing device 2A prints a standard density setting pattern 31A on the medium 4 at the standard density setting.

[0035] Step S2 is a step of printing density setting patterns 33 for each of the multiple density settings by another printing device 2 different from one of the multiple printing devices 2 at a position adjacent to the standard density setting pattern 31 on the medium 4. In other words, step S2 is a step of printing the multiple density setting patterns 33 by the second printing device 2B at a position adjacent to the standard density setting pattern 31A on the medium 4. Step S3 is a step of updating the density of the density setting pattern 33 that is closest to the density of the standard density setting pattern 31 among the multiple density setting patterns 33 as the standard density setting of the other printing device 2, the second printing device 2B. Note that step S1 and step S2 may be performed first or second.

[0036] According to the first calibration method, the density of the density setting pattern 33 that is closest to the density of the standard density setting pattern 31 printed by one printing device 2 can be updated as the standard density setting of the other printing device 2. This makes it easy to match the density setting of one printing device 2 with the density setting of the other printing device 2. As a result, it is easy to unify the density between the machines of the multiple printing devices 2. Also, according to the first calibration method, the standard density setting pattern 31 and the multiple density setting patterns 33 of the graduated density pattern 32 are adjacent to each other. Therefore, it is easy to compare the standard density setting pattern 31 with the multiple density setting patterns 33. As a result, it is easy to recognize the density setting pattern 33 that is closest to the density of the standard density setting pattern 31 among the multiple density setting patterns 33 of the graduated density pattern 32. The comparison between the standard density setting pattern 31 and the multiple density setting patterns 33 may be performed by human visual inspection or by a device such as a colorimeter.

[0037] It is preferable to avoid the standard density setting pattern 31 and the multiple density setting patterns 33 from overlapping with each other. This is desirable from the viewpoint of comparing the standard density setting pattern 31 and the multiple density setting patterns 33. If there is an area where the standard density setting pattern 31 and the multiple density setting patterns 33 overlap with each other, it becomes difficult to grasp the accurate density. On the other hand, it is also preferable to avoid the occurrence of gaps between the standard density setting pattern 31 and the multiple density setting patterns 33 that are adjacent to each other. This is also desirable from the viewpoint of comparing the standard density setting pattern 31 and the multiple density setting patterns 33. If the base material of the medium 4 is exposed between the standard density setting pattern 31 and the multiple density setting patterns 33 that are adjacent to each other, it becomes difficult to judge visually. This is because the standard density setting pattern 31 and the multiple density setting patterns 33 are separated from each other.

[0038] A case will be described where the standard density setting pattern 31 is printed by the second printing device 2B. FIG. 8 is a diagram illustrating an example of a calibration test pattern 35. In the example shown in FIG. 8, the standard density setting pattern 31 is printed by the second printing device 2B, and the stepped density pattern 32 is printed by the first printing device 2A. The standard density setting pattern 31 printed by the second printing device 2B is identified as the standard density setting pattern 31B. Also, the stepped density pattern 32 printed by the first printing device 2A is identified as the stepped density pattern 32A.

[0039] In the example shown in FIG. 8, among the multiple density setting patterns 33 of the stepped density pattern 32A, the density setting pattern 33 closest to the density of the standard density setting pattern 31B is the density setting pattern 33B. The density setting pattern 33B is not the standard density setting. The density setting pattern 33B is a density setting of +1 grade. In other words, the density setting of +1 grade of the first printing device 2A is equivalent to the standard density setting of the second printing device 2B. Therefore, if the density of +1 grade of the first printing device 2A is updated as the standard density setting of the first printing device 2A, the density can be unified between the first printing device 2A and the second printing device 2B.

[0040] As shown in the example of FIG. 6 and the example of FIG. 8, the density of the standard density setting unified among the multiple printing devices 2 may differ depending on whether the standard density setting pattern 31 is printed by the first printing device 2A or the second printing device 2B. In such a case, the density of the density setting pattern 33D shown in FIG. 6 and the density of the density setting pattern 33B shown in FIG. 8 may each be a candidate for the density to be unified. The candidate for the density to be unified is called a candidate density. When there are multiple candidate densities, it is preferable to adopt the darkest density among the multiple candidate densities. In the above example, the candidate density is darker when the standard density setting pattern 31 is printed by the second printing device 2B than when the standard density setting pattern 31 is printed by the first printing device 2A. Therefore, the density of the density setting pattern 33B, which is the candidate density when the standard density setting pattern 31 is printed by the second printing device 2B, is adopted.

[0041] As shown in FIG. 9, the second calibration method includes steps S11, S12, and S13. Step S11 is a step of printing a standard density setting pattern 31 on a medium 4 at a standard density setting by at least two printing devices 2 of the multiple printing devices 2. The standard density setting patterns 31 printed by the at least two printing devices 2 may be printed on different media 4 or on the same medium 4. Step S12 is a step of printing a density setting pattern 33 for each of the multiple density settings by another printing device 2 at a position adjacent to the standard density setting pattern 31 for each of the standard density setting patterns 31. The other printing device 2 is a printing device 2 of the multiple printing devices 2 that is different from the printing device 2 that printed the standard density setting pattern 31.

[0042] Either step S11 or step S12 may be performed first or second. Steps S11 and S12 print a plurality of combinations of adjacent standard density setting patterns 31 and a plurality of density setting patterns 33. Step S13 is a step for updating the density of the density setting pattern 33 that is closest to the density of the standard density setting pattern 31 in one of the plurality of combinations as the standard density setting of the other printing device 2.

[0043] According to the second calibration method, the density of the density setting pattern 33 that is closest to the density of the adjacent standard density setting pattern 31 among the multiple density setting patterns 33 can be updated as the standard density setting of the other printing device 2. This makes it easy to match the density setting of one printing device 2 with the density setting of the other printing device 2. As a result, it is easy to unify the density between the machines of the multiple printing devices 2. Furthermore, according to this calibration method, it is possible to print multiple combinations of one standard density setting pattern 31 and multiple adjacent density setting patterns 33. This makes it possible to have multiple combinations as options, thereby increasing the options for density settings.

[0044] In the second calibration method, it is preferable to select a candidate density for each of the multiple combinations, and update the standard density setting of the other printing devices 2 to the darkest density among the multiple candidate densities. This calibration method makes it possible to unify the standard density settings of the multiple printing devices 2 to the darkest density. Note that in the method of extracting the darkest density among the multiple candidate densities, it is preferable to print the multiple combinations on the same medium 4, as shown in Figure 10. This is because it is easy to get an overview of the multiple combinations.

[0045] The number of printing devices 2 included in the printing system 1 is not limited to two. The number of printing devices 2 included in the printing system 1 may be more than two. As shown in FIG. 11, a printing system 10 including three printing devices 2 will be described. The printing system 10 has the same configuration as the printing system 1, except that the printing system 10 includes a third printing device 2C. Therefore, among the configurations of the printing system 10, the same components as those of the printing system 1 are given the same reference numerals as those of the printing system 1, and detailed descriptions thereof will be omitted. In addition, the third printing device 2C has the same configuration as the first printing device 2A and the second printing device 2B. Therefore, among the configurations of the third printing device 2C, the same components as those of the first printing device 2A and the second printing device 2B are given the same reference numerals as those of the first printing device 2A and the second printing device 2B, and detailed descriptions thereof will be omitted. The third printing device 2C is connected to a computer 3. The third printing device 2C and the computer 3 can communicate with each other.

[0046] As shown in FIG. 12, the third calibration method includes six steps from step S31 to step S36. Step S31 is a step of initializing a variable N by substituting 0 into the variable N. The variable N is a variable for counting the ordinal numbers of multiple printing devices 2. Step S32 is a step of incrementing the variable N by adding 1 to the variable N. Step S33 is a step of printing the standard density setting pattern 31 on the medium 4 at the standard density setting by the Nth printing device 2. Step S33 corresponds to printing the standard density setting pattern 31 on the medium 4 at the standard density setting by one printing device 2.

[0047] For example, when N=1, step S33 corresponds to printing a standard density setting pattern 31A on the medium 4 at the standard density setting by the first printing device 2A. In the third calibration method, as shown in Fig. 13, the standard density setting pattern 31A is printed on the medium 4 at the standard density setting by the first printing device 2A. In a printing system 10 having three printing devices 2, two blank areas BL are formed in the standard density setting pattern 31. The number K of blank areas BL formed in the standard density setting pattern 31 is generalized by the following formula (1). K = M - 1 (1) M is the number of printing devices 2 included in the printing system 10, and is a natural number equal to or greater than two.

[0048] 12, step S34 is a step of printing density setting patterns 33 for each of a plurality of density settings by another printing device 2. Step S34 corresponds to printing density setting patterns 33 for each density setting by another printing device 2 different from one printing device 2 among the plurality of printing devices 2 at a position adjacent to the standard density setting pattern 31 on the medium 4.

[0049] When N=1, step S34 corresponds to printing a density setting pattern 33 for each density setting by each of the second printing device 2B and the third printing device 2C. By step S34, a stepped density pattern 32B and a stepped density pattern 32C are printed adjacent to the standard density setting pattern 31A, as shown in Fig. 14. The stepped density pattern 32B is the stepped density pattern 32 printed by the second printing device 2B. The stepped density pattern 32C is the stepped density pattern 32 printed by the third printing device 2C.

[0050] Returning to Fig. 12, step S35 is a step for judging whether or not there is a candidate density. Step S35 corresponds to a density judgment for judging whether or not there is a density setting pattern 33 close to the density of the standard density setting pattern 31 among the multiple density setting patterns 33. When the judgment result in step S35 is YES, that is, when the judgment result is NO, the process proceeds to step S36. When the judgment result in step S35 is NO, that is, when the judgment result is NO, the process proceeds to step S32.

[0051] Here, it is determined whether or not there is a candidate density in the calibration test pattern 35 shown in FIG. 14. The density of the density setting pattern 33B in the graduated density pattern 32B by the second printing device 2B is equivalent to the density of the standard density setting pattern 31A by the first printing device 2A. On the other hand, the graduated density pattern 32C by the third printing device 2C does not have a density setting pattern 33 close to the density of the standard density setting pattern 31A by the first printing device 2A. For this reason, it is determined that there is no candidate density in the calibration test pattern 35 shown in FIG. 14. Therefore, in this case, the process proceeds to step S32 shown in FIG. 12.

[0052] If the result of the density determination in step S35 is "no", steps S32, S33, S34, and S35 are repeated until the result of the density determination in step S35 is "yes". In other words, the third calibration method includes repeating the printing of the standard density setting pattern 31 by the other printing device 2, the printing of multiple density setting patterns 33, and the density determination until the result of the density determination is "yes" when the result of the density determination is "no". As shown in FIG. 14, there is no candidate density in the standard density setting pattern 31A by the first printing device 2A. Therefore, next, a candidate density is searched for in the standard density setting pattern 31B by the second printing device 2B.

[0053] FIG. 15 is a diagram for explaining an example of the calibration test pattern 35. The example shown in FIG. 15 is a calibration test pattern 35 including a standard density setting pattern 31B printed by the second printing device 2B. In the example shown in FIG. 15, the density of the density setting pattern 33E in the graduated density pattern 32A by the first printing device 2A is equivalent to the density of the standard density setting pattern 31B by the second printing device 2B. The density of the density setting pattern 33B in the graduated density pattern 32C by the third printing device 2C is equivalent to the density of the standard density setting pattern 31B by the second printing device 2B. For this reason, the calibration test pattern 35 shown in FIG. 15 is determined to have a candidate density. Therefore, in this case, the process proceeds to step S36 shown in FIG. 12.

[0054] Step S36 is a step of setting the standard density. Step S36 corresponds to updating the density of the density setting pattern 33 close to the density of the standard density setting pattern 31 as the standard density setting of the other printing device 2. In the example of the calibration test pattern 35 shown in FIG. 15, the first printing device 2A and the third printing device 2C correspond to the other printing device 2. In step S36, the density of the density setting pattern 33E in the first printing device 2A is set as the standard density setting of the first printing device 2A. Furthermore, in step S36, the density of the density setting pattern 33B in the third printing device 2C is set as the standard density setting of the third printing device 2C. That is, the density of the -2 grade in the first printing device 2A is set as the standard density setting in the first printing device 2A. Also, the density of the +1 grade in the third printing device 2C is set as the standard density setting in the third printing device 2C.

[0055] According to the third calibration method, the density of the density setting pattern 33 that is closest to the density of the standard density setting pattern 31 printed by one printing device 2 can be updated as the standard density setting of the other printing device 2. This makes it easy to match the density setting of one printing device 2 with the density setting of the other printing device 2. As a result, it is easy to unify the density between the machines of the multiple printing devices 2. In addition, the third calibration method includes printing the standard density setting pattern 31 and the multiple density setting patterns 33 by the other printing device 2 when the result of the density determination is null. This makes it easy to reduce the necessary printing compared to the case where a combination of the standard density setting pattern 31 and the multiple density setting patterns 33 is printed by all printing devices 2 from the beginning.

[0056] In the third calibration method, when there are multiple candidate densities with different density grades, it is preferable to adopt the darkest density among the multiple candidate densities. FIG. 16 is a diagram for explaining an example of a calibration test pattern 35. The example shown in FIG. 16 is a calibration test pattern 35 including a standard density setting pattern 31C printed by the third printing device 2C. In the example shown in FIG. 16, the density of the density setting pattern 33D among the stepped density pattern 32A by the first printing device 2A is equivalent to the density of the standard density setting pattern 31C by the third printing device 2C. The density of the density setting pattern 33C among the stepped density pattern 32B by the second printing device 2B is equivalent to the density of the standard density setting pattern 31C by the third printing device 2C. The candidate density in the example shown in FIG. 16 is darker than the candidate density in the example shown in FIG. 15. Therefore, in this case, the candidate density in the example shown in FIG. 16 is adopted. That is, in this case, the density of the -1 grade in the first printing device 2A is set as the standard density setting in the first printing device 2A. Moreover, the density of the +2 grade in the second printing device 2B is set as the standard density setting in the second printing device 2B.

[0057] When each of the multiple printing devices 2 is capable of printing on the medium 4 with ink of multiple colors, a method of calibration based on a calibration test pattern 35 printed with ink of one of the multiple colors may be adopted. In this case, each of the multiple printing devices 2 is capable of printing on the medium 4 with ink of multiple colors, and has multiple density settings for each ink color. This calibration method is called the fourth calibration method. The fourth calibration method can be applied to any of the first calibration method, the second calibration method, and the third calibration method. According to this calibration method, a standard density setting set for one color of the multiple colors can be applied to the standard density settings of the other colors. This makes it possible to avoid printing the calibration test patterns 35 for all colors.

[0058] A method of calibrating for each type of medium 4 can also be adopted. This calibration method is called the fifth calibration method. The appearance of the ink density and color may differ depending on the type of medium 4. In addition, the degree of ink bleeding may differ depending on the type of medium 4. For this reason, the fifth calibration method, which calibrates for each type of medium 4, is preferable. According to the fifth calibration method, it is easy to reduce density differences due to the type of medium 4. For the fifth calibration method, it is effective to store the type of medium 4 on which the calibration was performed as a record. For example, by storing the history of the type of medium 4 on which the calibration was performed in the memory 13 of the printing device 2 or the memory of the computer 3, it is possible to determine whether the medium 4 is a new medium. This makes it possible to quickly recognize whether the medium 4 is one on which calibration should be performed.

[0059] According to the calibration method of the present embodiment, in a printing system 1 or a printing system 10 having a plurality of printing devices 2, the print density can be unified among the machines of the plurality of printing devices 2. This is suitable, for example, when the same printed matter is produced by the plurality of printing devices 2. If there is a difference in density among the machines of the plurality of printing devices 2, the variation in density and color tone in the same printed matter becomes noticeable. The machine difference among the plurality of printing devices 2 is considered to occur, for example, due to aging. According to the calibration method of the present embodiment, when the same printed matter is produced by the plurality of printing devices 2, the variation in density and color tone in the plurality of printed matter can be suppressed to be low. Note that in this embodiment, an inkjet printer is applied as the printing device 2. However, the printing device 2 is not limited to an inkjet printer. For example, a laser printer can also be applied as the printing device 2. [Explanation of symbols]

[0060] Reference Signs List 1...printing system, 2...printing device, 2A...first printing device, 2B...second printing device, 2C...third printing device, 3...computer, 4...medium, 5...inkjet head, 6...carriage, 10...printing system, 11...communication interface, 12...control unit, 13...memory, 14...driving signal generating circuit, 15...transport motor, 16...carriage motor, 21...transport control unit, 22...carriage control unit, 23...ejection control unit, 26...density setting data, 27...standard density setting pattern data, 28...step density pattern data, 31...standard density setting pattern, 31A...standard density setting pattern, 31B...standard density setting pattern, 31C...standard density setting pattern, 32...stepped density pattern, 32A...stepped density pattern, 32B...stepped density pattern, 32C...stepped density pattern, 33...density setting pattern, 33A...density setting pattern, 33B...density setting pattern, 33C...density setting pattern, 33D...density setting pattern, 33E...density setting pattern, 35...calibration test pattern, BL...blank area.

Claims

1. 1. A calibration method for correcting differences between a plurality of printing devices that print on a printing medium with a printing agent by depositing the printing agent on the printing medium, comprising: each of the plurality of printing devices has a plurality of density settings for the density of the printing agent to be applied to the printing medium, including a standard density setting that is a standard density; The calibration method includes: printing a standard density setting pattern on the printing medium at the standard density setting by one of the plurality of printing devices; printing a density setting pattern for each of the plurality of density settings by a printing device other than the one printing device among the plurality of printing devices at a position adjacent to the standard density setting pattern on the printing medium; updating the density of the density setting pattern that is closest to the density of the standard density setting pattern among the plurality of density setting patterns as the standard density setting of the other printing device. Calibration method.

2. 1. A calibration method for correcting differences between a plurality of printing devices that print on a printing medium with a printing agent by depositing the printing agent on the printing medium, comprising: each of the plurality of printing devices has a plurality of density settings for the density of the printing agent to be applied to the printing medium, including a standard density setting that is a standard density; The calibration method includes: printing a standard density setting pattern on the printing medium at the standard density setting by at least two of the printing devices of the plurality of printing devices; printing a density setting pattern for each of the plurality of density settings at a position adjacent to the standard density setting pattern by a printing device other than the printing device that printed the standard density setting pattern among the plurality of printing devices; updating the density of a density setting pattern that is closest to the density of the standard density setting pattern among the plurality of density setting patterns in one of the combinations of one of the standard density setting patterns and a plurality of the density setting patterns adjacent to the one of the standard density setting patterns as the standard density setting of the other printing device; Calibration method.

3. In each of the plurality of combinations, the density of the density setting pattern that is closest to the density of the standard density setting pattern among the plurality of density setting patterns is set as a candidate density; updating the darkest density among the plurality of candidate densities as the standard density setting of the other printing device; The calibration method according to claim 2 .

4. each of the plurality of printing devices is capable of printing on the print medium with a plurality of colors of the printing agent, and has a plurality of density settings for each of the colors of the printing agent, the density setting including the standard density setting; updating the standard density setting of the other printing device, which is set based on a result of printing the standard density setting pattern and the plurality of density setting patterns with the printing agent of one color of the plurality of colors, as the standard density setting of the other color of the plurality of colors; The calibration method according to claim 1 .

5. 1. A calibration method for correcting differences between a plurality of printing devices that print on a printing medium with a printing agent by depositing the printing agent on the printing medium, comprising: each of the plurality of printing devices has a plurality of density settings for the density of the printing agent to be applied to the printing medium, including a standard density setting that is a standard density; The calibration method includes: printing a standard density setting pattern on the printing medium at the standard density setting by one of the plurality of printing devices; printing a density setting pattern for each of the plurality of density settings by a printing device other than the one printing device among the plurality of printing devices at a position adjacent to the standard density setting pattern on the printing medium; a density determination for determining whether or not the plurality of density setting patterns include a density setting pattern close to the density of the standard density setting pattern; When the result of the density determination is positive, updating the density of the density setting pattern close to the density of the standard density setting pattern as the standard density setting of the other printing device; When the result of the density determination is "no," printing the standard density setting pattern by the other printing device, printing the plurality of density setting patterns, and the density determination are repeated until the result of the density determination is "yes." Calibration method.

6. Implemented for each type of print medium; A calibration method according to any one of claims 1, 2 and 5.

7. 1. A printing method for printing a printing medium with a printing agent by depositing the printing agent on the printing medium, comprising: printing a standard density setting pattern on the printing medium at a standard density setting, which is a standard density among the plurality of density settings, by a first printing device among a plurality of printing devices having a plurality of density settings for the density of the printing agent to be applied to the printing medium; printing a density setting pattern for each of the plurality of density settings at a position adjacent to the standard density setting pattern on the print medium by a second printing device different from the first printing device among the plurality of printing devices; Printing method.

8. A test pattern printed on a print medium with a printing agent by depositing the printing agent on the print medium, a standard density setting pattern printed by a first printing device among a plurality of printing devices having a plurality of density settings for the density of the printing agent to be applied to the printing medium, at a standard density setting that is a standard among the plurality of density settings; and a density setting pattern printed for each of the plurality of density settings by a second printing device, which is different from the first printing device, among the plurality of printing devices, at a position adjacent to the standard density setting pattern. Test pattern.

Images