METHOD FOR MAINTENANCE OF PRINT HEAD IN INKJET PRINTING APPARATUS AND INKJET PRINTING APPARATUS USING SAME

Abstract

To enable operation cost to be reduced even if a failure occurs in a head module.SOLUTION: A control part 39 determines whether printing quality by a printing head 13 can be maintained by exchanging an arrangement position of a head module 25 in which a failure occurs on the basis of unique information of each head module 25 and unique information of the head module 25 in which the failure occurs in the case of detecting that the failure occurs in any of head modules 25. The exchange of the arrangement position is displayed in a display part 35 if it is determined that the printing quality can be maintained by exchanging the arrangement position. Then, replacement frequency with a new head module 25 can be reduced by exchanging the arrangement position between the displayed head module 25 and the head module 25 in which the failure occurs. Therefore, it is possible to reduce operation cost of a device even though the failure occurs in the head module 25.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for maintaining a print head in an inkjet printing apparatus and an inkjet printing apparatus using the same, and more particularly to a method for maintaining a print head composed of a plurality of head modules. [Background technology]

[0002] Conventionally, some inkjet printing devices of this type are equipped with a print head configured by arranging a plurality of head modules in the width direction of the printing paper. Each head module has a plurality of nozzles in at least the width direction of the printing paper, either in the transport direction or the width direction. The head module has a drive board for driving each nozzle, and a memory for storing the ejection characteristics of the head module. If the frequency of nozzles not ejecting in the head module becomes higher than a certain value, or if the number of nozzles that are not ejecting exceeds a predetermined value, a malfunction of the print head is reported, and maintenance of the print head is performed.

[0003] As a first method, for example, a head module in which a malfunction has occurred is replaced with a new head module (see, for example, Patent Document 1). Unique identification information is given to the head module. During maintenance, the identification information of a head module that has been removed due to a malfunction is compared with the identification information of an attached head module, and if the head module that has been removed due to a malfunction has been erroneously reattached, this is notified. This prevents a head module in which a malfunction has occurred due to a work error from being attached.

[0004] In the first method described above, there is a risk of density differences occurring between adjacent head modules. In such a situation, print quality will decrease. In view of this, a second method is, for example, to replace a defective head module with a new head module and then correct the ejection characteristics of the new head module (see, for example, Patent Document 2). This reduces density differences between adjacent head modules, and can suppress deterioration in print quality.

[0005] The second method requires time and effort to correct the ejection characteristics. Therefore, a third method is to replace the head module adjacent to the defective head module with a new head module that has an inverse density gradient in the width direction (see, for example, Patent Document 3). This makes it possible to suppress density unevenness at the joints between adjacent head modules with little effort. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-166708 A [Patent Document 2] JP 2013-78943 A [Patent Document 3] JP 2015-47833 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the conventional example having such a configuration has the following problems. That is, the conventional method is based on the premise that if a malfunction occurs in the print head, the head module is replaced with a new one. The print head is composed of multiple head modules. Therefore, it may be possible to restore the print quality to the same level as before the malfunction occurred by simply changing the position of the defective head module, without having to replace the defective head module with a new head module. Nevertheless, since the defective head module is replaced with a new one, when a malfunction occurs in the head module, the frequency of head module replacement increases. This results in a problem of increased operating costs for the device.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a maintenance method for a print head in an inkjet printing device that can reduce operating costs even if a malfunction occurs in the head module, and an inkjet printing device using the same. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention has the following configuration. That is, the invention described in claim 1 is a method for maintaining a print head in an inkjet printing device equipped with a print head composed of a plurality of head modules that print by ejecting ink onto a printing medium, the method comprising the steps of: detecting that a malfunction has occurred in any of the head modules that compose the print head; determining whether or not print quality by the print head can be maintained by treating the head module in which the malfunction has occurred as a defective head module and replacing the position of the defective head module in the print head based on unique information including ejection characteristics of each head module that composes the print head excluding the defective head module and the unique information of the defective head module; and, if it is determined that print quality can be maintained by the determination step, notifying the replacement of the position. The judgment step judges whether or not printing quality can be maintained by changing the position of the defective head module on the print head so that the defective head module is disposed at the end of the print head when the defective head module has caused a defect in ejection abnormality, or whether or not printing quality can be maintained by changing the position of the defective head module on the print head so that the difference in density distribution between adjacent portions of the head modules is within a certain range when the defective head module has caused a defect in density distribution. It is characterized by the above.

[0010] [Action and Effect] According to the invention described in claim 1, when a malfunction has occurred in one of the head modules, a judgment step judges whether the printing quality of the print head can be maintained by swapping the position of the defective head module based on the unique information of each head module and the unique information of the defective head module. If it is judged that the printing quality can be maintained by swapping the position, a notification step notifies the user of the swapping of the position. Therefore, by swapping the position of the notified head module with the defective head module, the frequency of replacement with a new head module can be reduced. Therefore, even if a malfunction occurs in a head module, the operating costs of the device can be reduced.

[0011] The unique information referred to here refers to a density distribution that indicates the relationship between the position and the ejection amount in the multiple nozzles that the head module has, the position of the non-ejecting nozzles, the frequency of non-ejection in the nozzles, and the like.

[0013] The judgment step can determine whether printing quality can be maintained by placing the defective head module at the end of the print head when a defective head module causes an ejection abnormality or a density distribution abnormality, and whether printing quality can be maintained by replacing it with another head module when a density distribution abnormality occurs.

[0014] The invention described in claim 2 is a method for maintaining a print head in an inkjet printing device equipped with a print head composed of a plurality of head modules that print by ejecting ink onto a printing medium, the method comprising the steps of: detecting that a malfunction has occurred in any of the head modules that compose the print head; determining whether or not the print quality of the print head can be maintained by replacing the position of the defective head module in the print head based on unique information including the ejection characteristics of each head module that composes the print head excluding the defective head module and the unique information of the defective head module; and, if it is determined that the print quality can be maintained by the determination step, reporting the replacement of the position.If it is determined in the judgment step that the print quality cannot be maintained by replacing the defective head module with another head module, a database storing unique information on a plurality of new head modules is accessed, and a new head module capable of maintaining the print quality by replacing the defective head module is searched for based on the unique information of the defective head module and the unique information of each head module constituting the print head excluding the defective head module, and if the new head module capable of maintaining the print quality is determined to be a new head module, an exchange suggestion step is performed to suggest the new head module. It is characterized by the above.

[0015] If it is determined in the judgment step that the print quality cannot be maintained by merely replacing the layout, a database is accessed, and a new head module capable of maintaining the print quality is searched for based on the unique information of the defective head module and the unique information of the other head modules of the print head excluding the defective head module. Then, in the replacement suggestion step, a new head module capable of maintaining the print quality is suggested. In this way, by replacing the defective head module with the new head module, a suitable head module can be obtained, and the print quality of the print head can be maintained.

[0016] In addition, in the present invention, it is preferable to carry out, together with the replacement suggestion step, an alternative suggestion step of comparing the print quality of a simple replacement in which the new head module is replaced with the defective head module based on the unique information of the new head module and the unique information of all head modules constituting the print head excluding the defective head module with the print quality of various replacements in which the arrangement positions of each head module excluding the defective head module are replaced with the new head module, and presenting the replacement with the one having higher print quality. (Claim 3) .

[0017] The print quality of a simple replacement in which the defective head module is replaced with a new head module is compared with the print quality of various replacements in which each head module of the print head is replaced with a new head module. Then, in an alternative proposal presentation step, the alternative with the higher print quality is also presented. This allows the user to increase the options when replacing the head module, allowing the head module to be replaced in a suitable way.

[0018] The invention described in claim 4 is a method for maintaining a print head in an inkjet printing device equipped with a print head composed of a plurality of head modules that print by ejecting ink onto a printing medium, the method comprising the steps of: detecting that a malfunction has occurred in any of the head modules that compose the print head; determining whether or not the print quality of the print head can be maintained by treating the head module in which the malfunction has occurred as a defective head module and replacing the position of the defective head module in the print head based on unique information including the ejection characteristics of each head module that composes the print head excluding the defective head module and the unique information of the defective head module; and, if it is determined that the print quality can be maintained by the determination step, reporting the replacement of the position. When the head module can be attached to the print head in a posture facing either the feed direction in the transport direction of the print medium or the counter-feed direction opposite to the feed direction, the head module has an attachment direction, either the feed direction or the counter-feed direction, in the unique information, and in the determination step, when the attachment direction in the unique information of the head module differs from the attachment direction of the head module, the attachment direction of the unique information is updated to the correct direction, and, for any unique information that has directionality, it is inverted to a direction perpendicular to the transport direction of the print medium. It is characterized by the above.

[0019] When the head module can be mounted in the feed direction and the counter-feed direction, the mounting direction is included in the unique information. When the mounting direction in the unique information of the head module being judged differs from the actual mounting direction of the head module, the mounting direction of the unique information is updated to the correct direction, and the unique information that has directionality is inverted to a direction perpendicular to the transport direction of the printing medium. Therefore, in the judgment step, a correct judgment based on the unique information can be made according to the mounting direction.

[0020] In the present invention, it is preferable that, prior to the determining step, an installation direction detecting step is performed to detect the installation direction of each head module constituting the print head. (Claim 5) .

[0021] By carrying out the mounting direction detection step, it is possible to make a correct determination based on the unique information in accordance with the mounting direction of the head module in the determination step.

[0022] Also, Claim 6 The invention described in is an inkjet printing device equipped with a print head composed of a plurality of head modules that eject ink onto a printing medium to perform printing, the inkjet printing device comprising: a transport unit that transports the print medium in a predetermined transport direction; a control unit that operates the print head to print onto the print medium; a detection unit that detects that a malfunction has occurred in any of the head modules that constitute the print head; a head memory that is provided for each of the head modules and that stores unique information including ejection characteristics; a determination unit that determines whether or not printing quality by the print head can be maintained by replacing the position of the defective head module in the print head based on the unique information about each head module that constitutes the print head excluding the defective head module and the unique information of the defective head module; and a notification unit that notifies of the replacement of the position when the determination unit determines that printing quality can be maintained. The judgment unit judges whether or not printing quality can be maintained by rearranging the position of the defective head module on the print head so that the defective head module is arranged at the end of the print head when the defective head module has caused a malfunction such as an ejection abnormality, or whether or not printing quality can be maintained by rearranging the position of the defective head module on the print head so that the difference in density distribution between adjacent portions of the head modules is within a certain range when a malfunction in density distribution of the defective head module has occurred. It is characterized by the above.

[0023] [Actions and Effects] Claim 6According to the invention described in the above, the control unit operates the print head to perform printing while the transport unit transports the print medium. If the detection unit detects a malfunction in a head module, the judgment unit judges whether the print quality by the print head can be maintained by swapping the position of the defective head module based on the unique information of each head module and the unique information of the defective head module. If it is determined that the print quality can be maintained by swapping the position, the notification unit notifies the swapping of the position. Therefore, by swapping the position of the notified head module with the defective head module, the frequency of replacement with a new head module can be reduced. Therefore, even if a malfunction occurs in a head module, the operating costs of the device can be reduced. Effect of the Invention

[0024] According to the print head maintenance method for an inkjet printing device of the present invention, when a malfunction in one of the head modules is detected in the detection step, a determination step is made as to whether the print quality of the print head can be maintained by swapping the position of the defective head module based on the unique information of each head module and the unique information of the defective head module. If it is determined that the print quality can be maintained by swapping the position, a notification step is made of the swapping of the position. Therefore, by swapping the position of the notified head module with the defective head module, the frequency of replacement with a new head module can be reduced. Therefore, the operating costs of the device can be reduced even if a malfunction occurs in a head module. [Brief description of the drawings]

[0025] [Figure 1] 1 is a diagram illustrating the overall configuration of an inkjet printing apparatus according to an embodiment. [Diagram 2] FIG. 2 is a plan view showing the positional relationship between a print head and continuous paper. [Diagram 3] FIG. 13 is a schematic diagram showing an example of unique information. [Figure 4]FIG. 4 is a schematic diagram showing the unique information of the head modules that make up the print head arranged side by side. [Diagram 5] 5 is a flowchart showing a process flow during a printing operation. [Figure 6] 10 is a flowchart showing a flow of processing during maintenance processing. [Figure 7] FIG. 13A is a schematic diagram showing an arrangement of unique information indicating a current state, and FIG. 13B is a schematic diagram showing an arrangement of unique information indicating a state after being rearranged based on density distribution. [Figure 8] 13A is a schematic diagram showing a list of unique information indicating a current state, and FIG. 13B is a schematic diagram showing a list of unique information indicating a state after the list has been rearranged based on the position of an abnormal nozzle. [Figure 9] 13 is a schematic diagram showing a sequence of unique information used to explain a case where replacement is performed based on a severity tolerance threshold. FIG. [Figure 10] 13 is a diagram showing a configuration for determining the mounting direction as viewed from the transport direction. FIG. [Figure 11] 13A shows the arrangement of unique information when the mounting direction is −1, and FIG. 13B shows the arrangement of unique information when the mounting direction is determined to be +1. [Figure 12] 5A and 5B are schematic diagrams illustrating the relationship between the mounting direction and the flow path direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a diagram showing the overall configuration of an inkjet printing apparatus according to an embodiment of the present invention, Fig. 2 is a plan view showing the positional relationship between a print head and continuous paper.

[0027] <Device configuration>

[0028] The inkjet printing device 1 includes a paper feed unit 3, a printing device 5, and a paper discharge unit 7. The inkjet printing device 1 is communicatively connected to a head module station 9. The inkjet printing device 1 also receives print data, which is data for a printed matter, from a host computer (not shown).

[0029] The paper feed unit 3 unwinds, for example, a roll of the continuous paper WP in the transport direction X. The paper feed unit 3 is loaded with a roll of the continuous paper WP with its rotation axis facing in the width direction Y perpendicular to the transport direction X. The printing device 5 takes in the continuous paper WP unwound from the paper feed unit 3 and performs a printing process on the continuous paper WP. The printed continuous paper is wound around a horizontal axis in the paper discharge unit 7.

[0030] The printing device 5 includes a drive roller 11, a print head 13, a plurality of transport rollers 15, a drying unit 17, a scanning unit 19, a drive roller 21, and a bottom surface imaging unit 23.

[0031] The drive roller 11 takes in the web paper WP from the paper feed section 2 and transports the web paper WP in the transport direction X. The print head 13 is disposed downstream of the drive roller 11 in the transport direction X. The print head 13 includes a plurality of head modules 25. The print head 13 ejects ink onto the top surface of the web paper WP to form an image. The print head 13 will be described in detail later.

[0032] A drying unit 17 is disposed downstream of the print head 15. The drying unit 17 dries the ink ejected onto the web paper WP. A scanning unit 19 is disposed downstream of the drying unit 17. The scanning unit 19 scans the dried image on the web paper WP. A drive roller 21 is disposed downstream of the scanning unit 19. The drive roller 21 sends the web paper WP scanned by the scanning unit 19 to the paper discharge unit 7.

[0033] A bottom surface photographing unit 23 is disposed between the bottom surface of the print head 13 and the top surface of the continuous paper WP. This bottom surface photographing unit 23 is configured to be movable between a photographing position directly below the bottom surface of the print head 13 and a standby position offset to the side from the print head 13. The bottom surface photographing unit 23 photographs the bottom surfaces (nozzle surfaces) of each head module 25 that constitutes the print head 13.

[0034] As shown in Fig. 2, the print head 13 is made up of a plurality of head modules 25. Each head module 25 has a plurality of nozzles 27 in at least the transport direction X and the width direction Y. Fig. 2 shows a configuration with five head modules 25 as an example. In this embodiment, when it is necessary to distinguish between each of the five head modules 25, the head modules 25 will be referred to as head modules HM1 to HM5, respectively.

[0035] 2, the print head 13 is, for example, on the downstream side of the transport direction X, with the head module HM1 arranged on the left side in the width direction Y, the head module HM3 arranged to be spaced apart to the right of the head module HM1 in the width direction Y, and the head module HM5 arranged to be spaced apart to the right of the head module HM3 in the width direction Y. The print head 13 is, for example, on the upstream side of the transport direction X, with the head module HM2 arranged on the left side in the width direction Y, and the head module HM4 arranged to be spaced apart to the right of the head module HM2 in the width direction Y. When viewed from the upstream side of the print head 13 toward the transport direction X, the head modules HM1 to HM3 are arranged in the width direction Y such that the right end of the head module HM1 and the left end of the head module HM3 overlap both ends of the head module HM2. When viewed from the upstream side of the print head 13 in the transport direction X, the head modules HM3 to HM5 are arranged in the width direction Y so that the right end of the head module HM3 and the left end of the head module HM5 overlap both ends of the head module HM4. This arrangement of the head modules 25 is also called a "staggered arrangement."

[0036] The print head 13 has a length that exceeds the printing area PA of the web paper WP in the width direction Y. The printing area PA is the area in which images and the like are printed by the print head 13. This printing area PA is set at a position a predetermined distance inward from both ends of the web paper WP in the width direction Y. Furthermore, the length in the width direction Y that can be printed by the print head 13 exceeds the dimension in the width direction Y of the printing area PA and also exceeds the dimension in the width direction Y of the web paper WP. This is so that the print head 13 can print in the width direction Y of the web paper WP even if the web paper WP meanders in the transport direction X.

[0037] As shown in Fig. 2, the continuous paper WP has a gap between each printing area PA. For example, a test chart TC is printed in this gap. This test chart TC is made up of five individual charts formed for each head module 25. Each individual chart is formed, for example, by ejecting a predetermined pattern at a predetermined density from all the nozzles 27 constituting each head module 25. From these individual charts, various ejection characteristics for each head module 25 can be obtained.

[0038] Each head module 25 has a built-in head memory 29. Each head memory 29 stores information specific to each head module 25.

[0039] Here, reference is made to Fig. 3. Fig. 3 is a schematic diagram showing an example of unique information.

[0040] The unique information is information for each head module 25 including the ejection characteristics. For example, the unique information includes a serial number, a density distribution, correction information, an abnormal nozzle occurrence position, an abnormal nozzle occurrence frequency, and history and statistical information. The serial number is a manufacturing number of the head module 25, and is a unique number that does not overlap with other head modules. The density distribution is density information for all nozzles 27 of the head module 25. Specifically, for the nozzles 27 arranged in the width direction Y, the density of an image formed by applying a predetermined signal is arranged for each width direction Y. The correction information is information representing the value of a signal that is applied to each nozzle 27 to correct the density distribution, if there is a signal. The abnormal nozzle occurrence position is information representing the position of the nozzle 27 if the nozzle 27 has an abnormality such as non-ejection or chipping. The abnormal nozzle occurrence frequency is information indicating the frequency of abnormality occurrence in the nozzle 27 with an abnormality. The history and statistical information is information such as the number of times ink has been ejected by the head module 25 and the cumulative time that the nozzle has been attached to the print head 13 and powered.

[0041] The printing device 5 includes a head control unit 31, a data processing unit 33, a display unit 35, a database 37, and a control unit 39.

[0042] The head control unit 31 is operated by the control unit 39. The head control unit 31 is composed of a circuit board, and operates the print head 13 in response to a signal from the control unit 39 that is based on the print data. The head control unit 31 operates each head module 25 in response to a signal from the control unit 39. The head control unit 31 is capable of reading and writing from each head memory 29. The head control unit 31, for example, refers to unique information stored in the head memory 29, and corrects the signal from the control unit 39 based on that information. In addition, the head control unit 31 transmits the unique information read from the head memory 29 to the control unit 39.

[0043] The data processing unit 33 is connected to the scanning unit 19 and the bottom surface photographing unit 23. The scanning unit 19 photographs an image of the continuous paper WP printed by the print head 13 and converts the image into digital data. The image referred to here is an image in the print area PA and a test chart TC outside the print area PA. The data processing unit 33 judges the print quality of the printed image based on the data from the scanning unit 19. The data processing unit 33 also outputs information on the ejection characteristics based on the data of the test chart TC from the scanning unit 19. The bottom surface photographing unit 23 photographs the bottom surface of each head module 25 at a photographing position directly below the bottom surface of the print head 13. The photographed image of the bottom surface is output to the data processing unit 33 as digital data. The data processing unit 33 collects information indicating non-ejection or chipping of each nozzle 27 in each head module 25 based on the image of the bottom surface. The collected information is output to the control unit 39.

[0044] The display unit 35 is composed of a display device such as a liquid crystal display device. The display unit 35 displays information according to a signal from the control unit 39. For example, when a problem occurs in the head module 25, the display unit 35 displays the information. Although details will be described later, the display unit 35 displays information on the replacement of the arrangement position based on unique information, and information presenting alternatives based on a case of simple replacement with a new head module 25 and a case of various replacements in which the new head module 25 is arranged in various positions.

[0045] The database 37 is connected to the head module station 9. The head module station 9 is configured to allow a plurality of head modules 25 to be attached. The head module station 37 reads out unique information from the head memory 29 of each attached head module 25. The read out unique information is sent to the database 37. The database 37 stores unique information associated with each head module 25 connected to the head module station 9. The control unit 39 accesses the database 37 and refers to the unique information of each head module 25.

[0046] The control unit 39 comprehensively controls the drive rollers 11, 21, the drying unit 17, the scanning unit 19, the bottom surface imaging unit 23, the head control unit 31, the data processing unit 33, the display unit 35, and the database 37. The control unit 39 may also be connected to the inkjet printing device 1 for back surface printing via, for example, an inversion device (not shown) disposed downstream of the inkjet printing device 1. In such a case, the control unit 39 also communicates with the inkjet printing device 1 for back surface printing. For example, the control unit 39 acquires unique information and the like from the inkjet printing device 1 for back surface printing as external information.

[0047] The control unit 39 also obtains the unique information shown in FIG. 3 from the print head 13. Here, FIG. 4 is referred to. FIG. 4 is a schematic diagram showing the unique information of the head modules constituting the print head arranged in an order. The control unit 39 reads out the unique information of each head module 25 constituting the print head 13 via the head control unit 31. For example, the control unit 39 refers to the unique information arranged in order from the head module HM1 at the left end in the width direction Y to the head module HM5 at the right end. In this example, only the concentration distribution, the abnormal nozzle occurrence position, and the abnormal nozzle occurrence frequency are shown among the unique information. In this way, the control unit 39 grasps the unique information of all the head modules 25 constituting the current print head 13 at an appropriate timing.

[0048] The control unit 39 detects that a nozzle malfunction has occurred based on information from the data processing unit 33. When the control unit 39 detects that a nozzle malfunction has occurred, it displays on the display unit 35 what type of malfunction has occurred in which head module 25 constituting the print head 13. Furthermore, the control unit 39 does not simply notify the user that a malfunction has occurred, but determines whether print quality can be maintained by replacing the position of the head module 25 with the malfunction with another head module 25 constituting the current print head 13.

[0049] The term "maintaining the print quality" here refers to, for example, the following cases. The print quality of the head modules HM2 to HM4 near the center of the print head 13 will decrease if there is a non-ejecting nozzle 27 even at the end of each. Therefore, if there is a non-ejecting nozzle 27 at the left end of the head module HM2, the arrangement positions of the head module HM2 and the head module HM1 are swapped. The head module HM2 arranged at the leftmost end has its left end located outside the printing area PA, so it is used very infrequently. Therefore, it can be determined that the print quality can be maintained even if the head module HM2 is arranged at the left end in the width direction Y. In addition, as for the nozzle 27 whose frequency of non-ejection has reached a certain level or more, if it is located at the end of the head module 25, the nozzle 27 may be arranged so as to be located outside the printing area PA. It can be determined that the print quality can be maintained even if the arrangement is swapped so that the nozzle 27 is located at the end of the printing area PA, depending on the print data, even if it is not outside the printing area PA. Therefore, it is preferable to determine whether the print quality can be maintained by taking the print data into consideration.

[0050] In addition, the print quality also deteriorates when the difference in density distribution between adjacent parts of each head module 25 in the print head 13 is equal to or greater than a certain level. For example, as shown in FIG. 4, the difference between the adjacent parts of the head module HM2 and the head module HM3 is greater than that between other adjacent parts, and the difference in density distribution is equal to or greater than a certain level. In such a case, the print quality deteriorates. Therefore, for example, the positions of the head module HM2 and the head module HM5 are swapped so that the difference in density distribution between adjacent parts is within a certain level. Even if a defect in density distribution occurs in this way, the print quality may be maintained by swapping the positions. The control unit 39 refers to the unique information of the head module 25 in which the defect occurred and the unique information of the other head modules 25, and judges whether the print quality can be maintained by swapping the positions. The difference as the threshold value of the density distribution when making the above judgment is determined in advance by an experiment as the difference in density distribution at which the print quality can be maintained, and the value is stored in the control unit 39 as the threshold value.

[0051] The continuous paper WP described above corresponds to the "printing medium" in the present invention, the drive rollers 11, 21 and the transport roller 15 correspond to the "transport section" in the present invention, the scanning section 19, the bottom surface photographing section 23 and the data processing section 33 correspond to the "detection section" in the present invention, the control section 39 corresponds to the "judgment section" in the present invention, and the display section 35 corresponds to the "alert section" in the present invention.

[0052] <During printing>

[0053] The operation of the inkjet printing apparatus 1 configured as described above will be described with reference to Figures 5 and 6. Figure 5 is a flow chart showing the flow of processing during printing operation. Figure 6 is a flow chart showing the flow of processing during maintenance processing.

[0054] Step S1 Prior to a printing operation for executing one job, which is one block of printing processing, the control unit 39 receives unique information for all of the head modules 25 that make up the print head 15 .

[0055] Step S2 The control unit 39 executes printing. Specifically, the continuous paper WP is conveyed in the conveying direction X at a conveying speed according to the received print data and the printing conditions set in advance, while the drying unit 17 performs drying at a drying temperature according to the printing conditions. At that time, printing is performed while ejecting ink from the print head 13 based on the unique information. For example, if the unique information of the head module 25 includes correction information, the head control unit 31 corrects a signal according to the print data according to the correction information and outputs a signal to the head module 25 to perform printing processing. Note that it is preferable to print a test chart TC each time between the printing areas PA. The test chart TC includes a pattern that can obtain the density distribution of the head module 25 and a pattern that can determine non-ejection, chipping, etc.

[0056] Step S3 The control unit 39 operates the scanning unit 19 to capture an image of the printing surface of the continuous paper WP printed in step S2. The data processing unit 33 converts the image of the printing area PA and the image of the test chart TC printed outside the printing area PA into digital data.

[0057] Step S4 The control unit 39 operates the bottom surface photographing unit 23 to photograph the bottom surface of the print head 13. The data processing unit 33 converts the image of the bottom surface of the print head 13, the area including all of the head modules 25, into digital data.

[0058] Step S5 The data processing unit 33 calculates unique information for each head module 25 based on the digital data collected in steps S3 and S4. For example, it calculates density distribution based on the test chart TC, identifies the positions of nozzles that are not ejecting or are missing as abnormal nozzle occurrence positions based on the test chart TC and an image of the bottom surface of the print head 13, and calculates the frequency of abnormal nozzle occurrence. It also calculates history and statistical information according to the operating time, etc.

[0059] Step S6 The unique information for each head module 25 calculated in step S5 is transmitted to the control unit 39. The control unit 39 writes the unique information in the head memory 29 of the head module 25 via the head control unit 31 to update it.

[0060] Step S7 The control unit 39 refers to the unique information of each head module 25 updated in step S6, and judges whether or not there is a problem with the print quality based on the density distribution, the position where the abnormal nozzle occurs, the frequency of occurrence of the abnormal nozzle, etc. If the control unit 39 judges that there is no problem with the print quality, it ends the job. On the other hand, if the control unit 39 judges that there is a problem with the print quality, it branches the process to step S8.

[0061] Step S8 The control unit 39 executes maintenance processing for the print head 13 .

[0062] The above-mentioned step S7 corresponds to the "detection step" in the present invention.

[0063] <Maintenance processing>

[0064] Now, reference is made to FIG.

[0065] Step S11 The control unit 39 branches the process depending on whether or not it is possible to maintain the print quality by replacing the head module 25 for the print head 13. If it is possible to maintain the print quality by replacing the head module 25, the process branches to step S12, and if it is difficult to maintain the print quality by replacing the head module 25, the process branches to step S13.

[0066] The control unit 39 judges whether or not the printing quality can be maintained by replacing the head module 25, for example, as follows. Here, reference is made to Figures 7 and 8. Figure 7(a) shows the arrangement of unique information indicating the current state, and Figure 7(b) is a schematic diagram showing the arrangement of unique information indicating the state after replacement based on the density distribution. Figure 8(a) shows the arrangement of unique information indicating the current state, and Figure 8(b) is a schematic diagram showing the arrangement of unique information indicating the state after replacement based on the position of the abnormal nozzle.

[0067] For example, as shown in FIG. 7(a), the control unit 39 refers to the unique information of all the head modules 25 constituting the print head 13. Here, it is assumed that the density difference exceeds a threshold value in the adjacent portion between the head module HM2 and the head module HM3. As a result, it is assumed that the control unit 39 determines that a defect has occurred in the head module HM2. In other words, it is assumed that a defect in the density distribution has occurred. It may also be determined that a defect has occurred in the head module HM3 adjacent to the head module HM2. In that case, for example, it is preferable to determine that a defect has occurred in the head module 25 whose density distribution has changed significantly by comparing with the previous unique information.

[0068] The control unit 39 finds the density difference in each adjacent portion of the density distribution in the print head 13 for each combination in which the head module HM2 in which the defect is occurring is swapped adjacent to each of the remaining head modules HM1, HM3 to HM5 excluding the head module HM2 in which the defect is occurring, based on the density distribution of the unique information of all head modules 25 of the print head 13. If there is a combination that can eliminate the defect through this trial, the process proceeds to step S12.

[0069] The above-mentioned step S11 corresponds to the "determination step" in the present invention.

[0070] Step S12 The control unit 39 displays on the display unit 35 information on replacement of the combination of the head modules 25 that can eliminate the malfunction.

[0071] As the replacement information, the arrangement of the head modules 25 in the print head 13 for which the density difference is below the threshold value is presented. For example, in FIG. 7(a), if the head module HM2 and the head module HM5 are replaced and arranged, the density distribution between the head module HM2 determined to be defective and the adjacent head module HM3 will be below the threshold value as shown in FIG. 7(b). If only this combination has a density difference below the threshold value in the adjacent parts, the control unit 39 outputs the arrangement of the head modules 25 as shown in FIG. 7(b) to the display unit 35. If there are any other arrangements of the head modules 25 in the print head 13 for which the density difference is below the threshold value as a result of replacement, all of them are displayed.

[0072] The above-mentioned example is a case where the head module 25 has a defect related to the density distribution, but for example, a case where a non-ejection occurs in the head module 25 will be described. For example, as shown in FIG. 8(a), in the unique information of the head module HM4, the abnormal nozzle occurrence position is 1,5, and the abnormal nozzle occurrence frequency is 12345,13456. Here, the abnormal nozzle occurrence position 1,5 indicates the vicinity of the left end in the width direction Y. In addition, the abnormal nozzle occurrence frequency 12345,13456 indicates that ejection is rare. Therefore, the control unit 39 judges that a defect occurs in the head module HM4. From the abnormal nozzle occurrence position in the unique information, the control unit 39 knows that the nozzle 27 in which the non-ejection occurs in this head module HM4 is near the left end of the head module HM4 in the width direction Y. Therefore, when the control unit 39 considers the positional relationship between the print head 13, which is known in advance, and the printing area PA, it is understood that the abnormal nozzle occurrence position of the head module HM4 in which the defect occurs can be positioned outside the printing area PA. Therefore, the control unit 39 can determine that the print quality can be maintained by replacing the head module HM4 with the head module HM1.

[0073] In this case, in step S12, the control unit 39 displays on the display unit 35 information on replacing the head module 25 that can eliminate the malfunction, as shown in FIG. 8(b).

[0074] The above-mentioned step S12 corresponds to the "notification step" in the present invention.

[0075] Step S13 In step S11 described above, if it is difficult to maintain the print quality by replacing the head module 25, the process branches to step S13.

[0076] The control unit 39 refers to the database 37. The database 37 stores unique information of all the head modules 25 attached to the head module station 9 in association with each head module 25 attached to the head module station 9 by its serial number. The control unit 39 searches for a new head module 25 that can maintain print quality by replacing the defective head module 25 from among the head modules 25. As a result, when the control unit 39 finds a new head module 25 that can maintain print quality, it causes the display unit 35 to display the new head module 25 attached to the head module station 9. In this way, replacement information is presented to the operator.

[0077] Note that the control unit 39 preferably searches whether print quality can be maintained in various replacement cases, such as not only a simple replacement in which the defective head module 25 is replaced with a new head module 25, but also in which the position of the remaining head modules 25, excluding the defective head module 25, is replaced with a new head module 25. This allows for a more optimal arrangement of the head modules 25 in the print head 13, which may improve print quality.

[0078] The above-mentioned step S13 corresponds to the "exchange offering step" and the "alternative offer offering step" in the present invention.

[0079] Step S14 The operator of the inkjet printing apparatus 1 replaces or exchanges the head module 25 in accordance with the replacement information or the alternative proposal information displayed on the display unit 35.

[0080] Step S15 When the replacement or exchange work of the head modules 25 is completed, the control unit 39 acquires unique information from all of the head modules 25 that make up the print head 13.

[0081] Step S16 The control unit 39 determines whether the attached head module 25 is a new product or a second-hand product based on, for example, history and statistical information among the unique information of the attached head module 25.

[0082] Steps S17 and S18 If the head module 25 replaced in step S13 is new, a test chart TC is printed. Then, the scanning unit 19 and the bottom surface photographing unit 23 are operated to obtain unique information such as density information and abnormal nozzle occurrence position. Even if the head module 25 is new, a printing operation may be performed in a test machine to determine a reference voltage and the like during the manufacturing stage of the head module 25. In that case, the unique information is stored in the head memory 29. However, the unique information at the time the head module 25 is manufactured may differ from the unique information at the time it is attached. Therefore, this step S17 is performed to update the unique information of the head module 25 currently constituting the print head 13 to the latest state. This makes it possible to obtain the latest unique information.

[0083] Step S19 The control unit 39 calculates the optimal position of the new head module 25 based on the unique information of the new head module 25 that has been installed by replacement and has been updated to the latest state, taking into consideration the density distribution, the position where the abnormal nozzle occurs, etc.

[0084] Step S20 When the optimal position is calculated in step S19, the control unit 39 presents the position information by outputting it to the display unit 35. When this is presented, the user of the inkjet printing device 1 decides whether or not to replace the presented position information, and replaces it if necessary. This makes it possible to place the head module 25 in a more optimal position, thereby improving print quality.

[0085] <How to find the optimal layout>

[0086] In step S19 described above, the optimum position of the head module 25 is calculated based on the unique information that has been updated. A suitable method for calculating this will be described below.

[0087] Here, reference is made to Fig. 9. Fig. 9 is a schematic diagram showing a sequence of unique information for explaining a case where replacement is performed based on a severity tolerance threshold. In Fig. 9, as an example, the head module 25 is configured with seven modules, but some of them are omitted from the illustration.

[0088] For example, the optimal arrangement is determined for the head module HM1 located at the leftmost position in the width direction Y and the head module HM4 located at the center in the width direction Y. Here, the unique information stores, for example, the position where an abnormal nozzle occurs and its frequency of occurrence in association with each other. At first glance, this may look different from the unique information in FIG. 3 described above, but since the nozzle position and its frequency are associated with each other, it is the same unique information. The difference is that the unique information in FIG. 9 includes a severity tolerance threshold.

[0089] This severity tolerance threshold is a reference value for determining whether the severity is high or low when compared with the severity obtained as follows. It is preferable to arrange the head module 25 with a severity lower than this severity tolerance threshold. The severity tolerance threshold is set in advance so that it is small at the center in the width direction Y of the print head 13 and large at both ends in the width direction Y. In other words, it indicates that those with low severity can be arranged closer to the center of the print head 13, and those with high severity can be arranged closer to the ends. This is because the center of the print head 13 is required to have higher printing quality than the ends. In the following formula, the position of the nozzle 27 at the center of the head module 25 in the width direction Y is 2500.

[0090] Severity = SUM(abnormal nozzle occurrence frequency / |(difference from center of abnormal nozzle occurrence position)|, all nozzles)

[0091] Here, the SUM in the formula sign means adding up the abnormal nozzle occurrence frequency / |(difference between the abnormal nozzle occurrence position and the center)| for all nozzles 27. The severity is greater the higher the frequency with which abnormalities occur, and the closer the nozzle 27 with an abnormality is to the center, the greater the severity.

[0092] When the specific severity is calculated for the head modules HM1 and HM4, the following values ​​are obtained.

[0093] Head module HM1 severity=2 / |2500-2400|=0.02

[0094] Head module HM4 severity=50 / |2500-10|+200 / |2500-200|=0.1

[0095] The severity of the head module HM1 is 0.02, which is smaller than the severity tolerance threshold value of 0.10. Therefore, it can be determined that the severity is low and that the print quality can be maintained even in this position. The severity of the head module HM4 is 0.1, which is larger than the severity tolerance threshold value of 0.05. Therefore, it can be determined that the severity is not suitable for use in this position and that the print quality cannot be maintained in this position. Therefore, in this example, the head module HM1 with low severity is moved toward the center in the width direction Y of the print head 13, where the severity is lower than the severity tolerance threshold, and the head module HM4 with high severity is moved toward the end in the width direction Y of the print head 13, where the severity is lower than the severity tolerance threshold. Specifically, if the positions of the head module HM1 and the head module HM4 are swapped, this becomes the optimal position.

[0096] According to this embodiment, when a malfunction is detected in any of the head modules 25, the control unit 39 determines whether the printing quality of the print head 13 can be maintained by swapping the position of the defective head module 25, based on the unique information of each head module 25 and the unique information of the defective head module 25. If it is determined that the printing quality can be maintained by swapping the position, the swapping of the positions is displayed on the display unit 35. Therefore, by swapping the position of the displayed head module 25 with the defective head module 25, it is possible to reduce the frequency of replacement with a new head module 25. Therefore, even if a malfunction occurs in a head module 25, the operating costs of the device can be reduced.

[0097] <Installation direction>

[0098] In the above-described embodiment, the mounting direction of the head module 25 in the transport direction X does not matter. However, for example, some head modules 25 can be mounted in a "feed direction" in which one side faces downstream in the transport direction X, and in a "counter-feed direction" in which one side faces upstream in the transport direction X. When using such a head module 25, it is preferable to adopt the following configuration.

[0099] Here, reference is made to Fig. 10. Fig. 10 is a diagram showing the configuration for determining the mounting direction, as viewed from the transport direction.

[0100] The head module 25 has a direction determination mark 45 provided on a part of the bottom surface on which the nozzles 27 are formed. For example, the direction determination mark 45 indicates the feed direction when it is located on the right side in the width direction Y of the head module 25. On the other hand, for example, the direction determination mark 45 indicates the counter-feed direction when it is located on the left side in the width direction Y of the head module 25. The direction determination mark 45 is photographed by the bottom surface photographing unit 23, and the mounting direction is determined by the data processing unit 33. Note that this determination (mounting direction detection step) is preferably performed before the above-mentioned step S11.

[0101] When adopting such a configuration, it is preferable to configure the unique information as shown in Figures 11(a) and 11(b). Figure 11(a) shows the arrangement of unique information when the mounting direction is -1, and Figure 11(b) shows the arrangement of unique information when it is determined that the mounting direction is +1.

[0102] For example, if the mounting direction is the reverse feed direction, the mounting direction in the unique information is set to "-1", and if the mounting direction is the feed direction, the mounting direction in the unique information is set to "+1". In this way, the mounting direction of the head module 25 can be detected by reading the unique information. However, as a result of imaging by the bottom surface imaging unit 23, the mounting direction detected by the data processing unit 33 may not match the mounting direction in the unique information 29. For example, as shown in FIG. 11(a), the mounting direction in the unique information of the head memory 29 is set to "-1" (reverse feed direction). Meanwhile, as a result of imaging by the bottom surface imaging unit 23, the mounting direction is set to "+1". In this way, when the mounting direction in the unique information differs from the mounting direction indicated by the direction determination mark 45, the unique information is updated.

[0103] Specifically, among the unique information, information having directionality is inverted in the width direction Y, centered on the transport direction X of the web paper WP. As shown in Fig. 11(b), the ejection amount for each nozzle, which is related to the density distribution in Fig. 3, and the frequency of missing nozzles for each nozzle, which is related to the frequency of abnormal nozzle occurrence in Fig. 3, are swapped left and right with respect to Fig. 11(a).

[0104] In this way, by detecting the actual mounting orientation and updating the unique information, it is possible to make a correct decision based on the unique information according to the actual mounting orientation of the head module 25. Therefore, for example, it is possible to accurately make a decision on replacement in step S11 described above.

[0105] An example of how the head modules 25 are attached to the print head 13 will now be described with reference to Fig. 12. Fig. 12 is a schematic diagram illustrating the relationship between the attachment direction and the flow path direction.

[0106] For example, the print head 13 has a flow path direction of each head module 19 as shown in Fig. 12. In this flow path direction, that is, ink is supplied from the left side of the print head 13 to the head modules HM1, HM3, and HM5 on the downstream side in the transport direction X, and ink is supplied from the right side of the print head 13 to the head modules HM2 and HM4 on the upstream side in the transport direction X. In the print head 13 having such a flow path direction, for example, the head modules HM1, HM3, and HM5 on the downstream side in the transport direction X are mounted in a mounting direction of the feed direction "+1" as shown in Fig. 12. In addition, the head modules HM2 and HM4 on the upstream side in the transport direction X are mounted in a mounting direction of the counter-feed direction "-1", for example. Therefore, in the above-mentioned step S11, when attempting to swap head module HM1 and head module HM4, the mounting directions of head module HM1 and head module HM4 are reversed, so when determining whether printing quality can be maintained by swapping them, the head control unit 31 makes the determination taking into account the mounting direction from the data processing unit 33.

[0107] In step S11 described above, the replacement of the head modules 25 is considered. In this case, the replacement of the even-numbered head modules HM2 and HM4 is considered, and the replacement of the odd-numbered head modules HM1, HM3, and HM5 is considered. In these considerations, since the mounting directions are the same, the unique information is not inverted and is used as is. Furthermore, when considering the replacement of the even-numbered head modules HM2 and HM4 with the odd-numbered head modules HM1, HM3, and HM5, the unique information is inverted according to the mounting direction as described above. Also, for example, regardless of whether the head modules 25 attached to the print head 13 are even or odd, whether the difference in density distribution between the adjacent head modules 25 is reduced by reversing the mounting direction may be considered.

[0108] 12 is just an example, and for example, the head modules HM1, HM3, and HM5 on the upstream side in the transport direction X may be mounted in the counter-feed direction "-1", and the head modules HM2 and HM4 on the downstream side in the transport direction X may be mounted in the feed direction "+1", in the opposite direction to that of Fig. 12. Also, the print head 13 may be configured so that the mounting direction can be determined for each head module 25, regardless of whether it is upstream or downstream in the transport direction X.

[0109] The present invention is not limited to the above-described embodiment, but can be modified as follows.

[0110] (1) In the above-described embodiment, density distribution, abnormal nozzle occurrence position, and abnormal nozzle occurrence frequency were described as examples of defects occurring in the head module 25. However, the present invention can also be applied to defects other than these that affect print quality.

[0111] (2) In the above embodiment, the printing medium has been described by way of example using continuous paper WP. However, the present invention can be applied to any printing medium that can be printed on by the inkjet print head 13. For example, the present invention can be applied to a printing medium made of a plastic film.

[0112] (3) In the above-described embodiment, a configuration in which the print head 13 includes five head modules 25 has been described as an example. However, the present invention is not limited to this configuration. Also, while the print head 13 has been described as having a configuration in which the head modules 25 are arranged in a staggered manner, the present invention is not limited to this configuration. For example, the print head 13 may be configured with a plurality of head modules 25 arranged in a straight line in the width direction Y.

[0113] (4) In the above-described embodiment, the mounting direction is determined by the direction determination mark 45 photographed by the bottom surface photographing unit 23. However, the present invention is not limited to such a determination method. For example, when the head module 25 has an asymmetric shape between the upstream side and the downstream side when the width direction Y is used as a reference, specifically, when the bottom surface of the head module 25 has a trapezoidal shape, the mounting direction may be determined according to the lengths of the upper and lower bases. Also, instead of using the bottom surface photographing unit 23, a mechanical switch such as a limit switch may be provided on the print head 13 to which the head module 25 is attached, and the switch may be configured to operate only when the mounting direction is one direction.

[0114] (5) In the above-described embodiment, only the inkjet printing device 1 that prints on one side of the continuous paper WP has been described as an example. However, the present invention is not limited to this configuration. For example, there is a double-sided printing system in which the inkjet printing device 1 is connected to the inkjet printing device 1 for back side printing via an inversion device (not shown) arranged downstream of the inkjet printing device 1. In such a configuration, the control unit 39 may receive, as external information, unique information of the print head 13 in the inkjet printing device 1 for back side printing, and may replace or exchange the head modules 25 including the print head 13 for back side printing and the print head 13 for front side printing. [Industrial Applicability]

[0115] INDUSTRIAL APPLICABILITY As described above, the present invention is suitable for a maintenance method for a print head in an inkjet printing device and for an inkjet printing device using the same. [Explanation of symbols]

[0116] 1 … Inkjet printing device 3 … Paper feed section 5…Printing device 7 … Paper ejection section 9 … Head module station WP: Continuous paper X … Transport direction Y: Width direction 11,21 ... Drive roller 13 ... Print head 15 ... Transport roller 17 … Drying section 19 … Inspection Department 21 ... Drive roller 23 ... Bottom photographing section 25(HM1~HM5) … Head module 27 ... Nozzle 29... Head Memory 37 … Database 39 ... Control section 45 ... Directional mark

Claims

1. A method for maintaining a print head in an inkjet printing device having a print head constituted by a plurality of head modules that eject ink onto a print medium to perform printing, comprising the steps of: detecting that a malfunction has occurred in any of the head modules constituting the print head; a determination step of determining whether the print quality of the print head can be maintained by replacing the position of the defective head module in the print head based on unique information including the ejection characteristics of each head module constituting the print head excluding the defective head module and the unique information of the defective head module; a notification step of notifying the user of the change in the arrangement positions when it is determined that the print quality can be maintained by the determination step; Implemented the following: A maintenance method for a print head in an inkjet printing device, characterized in that the judgment step determines whether, when the defective head module has caused an ejection abnormality, printing quality can be maintained by rearranging the position of the defective head module on the print head so that the defective head module is positioned at the end of the print head, or whether, when the defective head module has caused a density distribution defect, printing quality can be maintained by rearranging the position of the defective head module on the print head so that the difference in density distribution between adjacent parts of the head modules is within a certain range.

2. A method for maintaining a print head in an inkjet printing device having a print head constituted by a plurality of head modules that eject ink onto a print medium to perform printing, comprising the steps of: detecting that a malfunction has occurred in any of the head modules constituting the print head; a determination step of determining whether the print quality of the print head can be maintained by replacing the position of the defective head module in the print head based on unique information including the ejection characteristics of each head module constituting the print head excluding the defective head module and the unique information of the defective head module; a notification step of notifying the user of the change in the arrangement positions when it is determined that the print quality can be maintained by the determination step; Implemented the following: If it is determined in the determination step that the print quality cannot be maintained by replacing the arrangement position of the defective head module in the print head, A method for maintaining a print head in an inkjet printing device, comprising: accessing a database storing unique information for a plurality of new head modules; searching for a new head module that can maintain printing quality by replacing the defective head module based on the unique information of the defective head module and the unique information of each head module that constitutes the print head excluding the defective head module; and performing an exchange presentation step to present the new head module if the new head module that can maintain printing quality is determined to be a new head module.

3. A method for maintaining a print head in an inkjet printing device according to claim 2, comprising: A method for maintaining a print head in an inkjet printing device, characterized in that, in addition to the replacement suggestion step, an alternative suggestion step is carried out in which, based on the unique information of the new head module and the unique information of all head modules that make up the print head excluding the defective head module, the printing quality of a simple replacement when the new head module is replaced with the defective head module is compared with the printing quality of various replacements when the arrangement positions of each head module excluding the defective head module are replaced with the new head module, and the one with higher printing quality is also suggested.

4. A method for maintaining a print head in an inkjet printing device having a print head constituted by a plurality of head modules that eject ink onto a print medium to perform printing, comprising the steps of: detecting that a malfunction has occurred in any of the head modules constituting the print head; a determination step of determining whether the print quality of the print head can be maintained by replacing the position of the defective head module in the print head based on unique information including the ejection characteristics of each head module constituting the print head excluding the defective head module and the unique information of the defective head module; a notification step of notifying the user of the change in the arrangement positions when it is determined that the print quality can be maintained by the determination step; Implemented the following: When the head module can be attached to the print head in a posture facing either a feed direction in a transport direction of the print medium or a counter-feed direction opposite to the feed direction, the head module has an attachment direction, either the feed direction or the counter-feed direction, in the unique information; A method for maintaining a print head in an inkjet printing device, characterized in that in the judgment step, if the mounting direction in the unique information of the head module is different from the mounting direction of the head module, the mounting direction of the unique information is updated to the correct direction, and any unique information that has directionality is reversed to a direction perpendicular to the transport direction of the printing medium.

5. A method for maintaining a print head in an inkjet printing device according to claim 4, comprising: A maintenance method for a print head in an inkjet printing device, comprising the steps of: prior to the determination step, performing an installation direction detection step of detecting the installation direction for each head module constituting the print head.

6. An inkjet printing device having a print head composed of a plurality of head modules that ejects ink onto a printing medium to perform printing, a transport unit that transports the print medium in a predetermined transport direction; a control unit that operates the print head to print on the print medium; a detection unit that detects when a malfunction occurs in any of the head modules that configure the print head; a head memory provided for each of the head modules, the head memory storing unique information including ejection characteristics; a determination unit that determines whether the printing quality of the print head can be maintained by determining, as a defective head module, the head module in which the defect has occurred, and by replacing the position of the defective head module in the print head based on the unique information about each head module constituting the print head excluding the defective head module and the unique information about the defective head module; a notification unit that notifies the user of the change in the arrangement positions when the determination unit determines that the print quality can be maintained; Equipped with The inkjet printing device is characterized in that the judgment unit judges whether, when the defective head module has caused an ejection abnormality, printing quality can be maintained by rearranging the position of the defective head module on the print head so that the defective head module is positioned at the end of the print head, or whether, when the defective head module has caused a density distribution defect, printing quality can be maintained by rearranging the position of the defective head module on the print head so that the difference in density distribution between adjacent parts of the head modules is within a certain range.

7. An inkjet printing device having a print head composed of a plurality of head modules that ejects ink onto a printing medium to perform printing, a transport unit that transports the print medium in a predetermined transport direction; a control unit that operates the print head to print on the print medium; a detection unit that detects when a malfunction occurs in any of the head modules that configure the print head; a head memory provided for each of the head modules, the head memory storing unique information including ejection characteristics; a determination unit that determines whether the printing quality of the print head can be maintained by determining, as a defective head module, the head module in which the defect has occurred, and by replacing the position of the defective head module in the print head based on the unique information about each head module constituting the print head excluding the defective head module and the unique information about the defective head module; a notification unit that notifies the user of the change in the arrangement positions when the determination unit determines that the print quality can be maintained; Equipped with Further comprising a database storing the unique information regarding a plurality of new head modules; When the determination unit determines that the print quality cannot be maintained by changing the arrangement position of the defective head module in the print head, an exchange suggestion unit that accesses the database, searches for a new head module that can maintain print quality by replacing the defective head module based on unique information of the defective head module and unique information of each head module constituting the print head excluding the defective head module, and suggests the new head module when the new head module that can maintain print quality is determined as a new head module.

Images