Inkjet printing device and cleaning method thereof

Abstract

To provide an inkjet printing device, in which a head to be cleaned is determined properly so that the head is advantageous in printing efficiency and a printing quality or the like more than before.SOLUTION: In the inkjet printing device, when cleaning should be started, a cleaning target head determining part 172 determines a printing head to be cleaned as a designated head, on the basis of a detected result (lack information LI) of an ejection state obtained from a printed image of an inspection pattern. Thereafter, an added-head selecting part 162 selects, as an additional head, a printing head that is advantageous in printing efficiency and a printing quality, by adding the printing head to the printing head to be cleaned, from residual heads which are printing heads other than the designated head. A cleaning execution control part 163 controls a cleaning mechanism 25 so that cleaning is executed to the designated head and the selected additional head.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an inkjet printing device and a cleaning method thereof, and more particularly to determining which printheads in an inkjet printing device to clean. [Background technology]

[0002] Inkjet printing devices that print by ejecting ink onto a substrate (printing medium) such as printing paper have been known for some time. Inkjet printing devices, when the ejection interval becomes long, problems such as drying of the ink due to evaporation of the solvent near the nozzles, the intrusion of air bubbles into the nozzles, and the adhesion of dust to the nozzles can occur during printing. When these problems occur, proper ejection and other operations cannot be performed, potentially resulting in poor printing. Therefore, maintenance is performed as needed to avoid these problems.

[0003] This maintenance can be broadly divided into cleaning of the print head (also called an "inkjet head") that ejects ink, and flushing, which forcibly ejects ink unrelated to the print content from the print head. Flushing can be performed while the print paper is being transported, but cleaning must be performed while the print paper is stopped. For this reason, if the proportion of time required for cleaning (cleaning frequency) increases, printing throughput decreases. On the other hand, if cleaning frequency is reduced in order to maintain high printing throughput, faded or blank areas (areas where ink does not adhere) will appear in the printed image, reducing print quality.

[0004] In relation to the inkjet printing device disclosed in this application, Patent Document 1 describes an inkjet printer that determines which heads should be cleaned based on check patterns printed on printing paper by ejecting ink from each head (see, for example, Figure 6 of the document). In this inkjet printer, a user visually checks the check patterns printed on printing paper to determine which heads (designated heads) need cleaning, and cleaning is then performed on the designated heads. Furthermore, an evaluation value (related to ejection defects) is calculated for each head based on pattern image data obtained by capturing an image of the check patterns on the printing paper. Heads that need cleaning are detected by comparing the evaluation value with a threshold value. A new threshold value to be used in the next process is obtained from the difference between the set of detected heads and the set of designated heads selected by the user (threshold value update) (see paragraph

[0039] ). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-176880 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, among the print heads in an inkjet printing device, the print heads that should be cleaned (hereinafter referred to as "heads to be cleaned") have been determined based on information such as the degree of ejection defects (so-called missing nozzles, etc.) in each print head, operating time, changes in printing conditions, etc. For example, as described above, an operator would visually inspect a check pattern printed on printing paper to determine the heads to be cleaned, or a control unit within the inkjet printing device would image the check pattern and detect ejection defects (missing nozzles, etc.) based on the pattern image data obtained, and the heads to be cleaned would then be determined based on the detection results.

[0007] However, such conventional methods for determining which heads to clean may not be able to maintain a sufficiently high printing throughput without causing print quality to drop below a desired level. On the other hand, cleaning other print heads simultaneously with the heads to be cleaned using such conventional methods may be more advantageous than conventional methods in terms of printing efficiency (throughput) and quality. However, it is difficult for a user to accurately determine which print heads are best to clean simultaneously, depending on the conditions and circumstances during printing operations, and to appropriately determine which heads to clean.

[0008] Therefore, in inkjet printing devices, there is a demand for a method of appropriately determining the head to be cleaned so as to be more advantageous than before in terms of printing efficiency, quality, and the like. [Means for solving the problem]

[0009] A first aspect of the present invention is an inkjet printing apparatus, comprising: a transport mechanism for transporting the print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing-machine-specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, When the additional head is selected by the additional head selection unit in response to the cleaning start instruction, the cleaning execution control unit causes the cleaning mechanism to perform cleaning on the designated head and the additional head. 、 The additional head selection unit selects, as the additional head, a print head that will improve at least one of printing efficiency and quality when it is subjected to cleaning together with the designated head from among the remaining heads. .

[0011] The present invention No. 2 The aspect of the present invention is the first aspect, Based on the printing machine-specific information, the additional head selection unit selects as the additional head a print head from among the remaining heads that, when included in the cleaning target, will require less time for cleaning than the time required for cleaning only the designated head.

[0012] The present invention Third The aspect of the present invention is the first aspect, Based on the printing machine-specific information, the additional head selection unit selects as the additional head a print head from among the remaining heads that, when included in the cleaning target, will not increase the time required for cleaning from the time required for cleaning only the designated head and will improve printing efficiency or quality.

[0013] The present invention Fourth The situation is 1. An inkjet printing device, comprising: a transport mechanism for transporting the print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing-machine-specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; The additional head selection unit selects, as the additional head, a print head whose condition will deteriorate due to drying when cleaning of only the designated head is executed among the remaining heads.

[0014] The present invention No. 5 The situation is 1. An inkjet printing device, comprising: a transport mechanism for transporting the print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing-machine-specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; The additional head selection unit selects the additional head based on information about the print job and in accordance with printing conditions of the print job to be printed after cleaning is performed on the designated head.

[0015] The present invention No. 6 The situation is 1. An inkjet printing device, comprising: a transport mechanism for transporting the print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing machine specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; a history information storage unit that stores information indicating the history of at least one of maintenance, ejection operation, and ejection defect inspection for each of the plurality of print heads; and Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; The additional head selection unit selects the additional head from the remaining heads based on the information stored in the history information storage unit.

[0016] The present invention Seventh The situation is 1. An inkjet printing device, comprising: a transport mechanism for transporting the print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing-machine-specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; The additional head selection unit The aforementioned When the printing unit includes print heads of different colors and the cleaning mechanism is configured to be able to clean print heads of the same color as a unit, based on the printing machine specific information, The aforementioned The additional head is selected from the remaining heads within a range that does not make the cleaning time longer than the cleaning time required for the print head of the color that requires the longest cleaning time among the designated heads.

[0017] The present invention No. 8 The third aspect is a cleaning method for an inkjet printing device that prints on a print medium by ejecting ink from a plurality of print heads onto the print medium while transporting the print medium, the method comprising: a cleaning start step of outputting a cleaning start instruction that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection step of selecting, when the cleaning start instruction is output, a print head from among the remaining heads to be cleaned together with the designated head as an additional head based on at least one of printing machine specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; a cleaning execution step of executing cleaning of the designated head and the additional head when the additional head is selected in response to the cleaning start instruction. 、 In the additional head selection step, a print head that will improve at least one of printing efficiency and quality when it is subjected to cleaning together with the designated head among the remaining heads is selected as the additional head. .

[0018] Other aspects of the present invention will be apparent from the above aspects of the present invention and the following description of the embodiments and their modifications, and therefore will not be described here. [Effects of the Invention]

[0019] According to a first aspect of the present invention, when cleaning is to be performed, a cleaning start instruction is output, specifying the print head to be cleaned as the designated head, based on information indicating the ejection status of multiple print heads in a printing unit. When this cleaning start instruction is output, a print head from among the remaining heads to be cleaned along with the designated head is selected as an additional head based on at least one of: printer-specific information indicating configurations or functions related to cleaning; information related to the print job; information indicating the dryness status of the remaining heads (i.e., print heads other than the designated head) among the multiple print heads; the ejection operation history of the remaining heads; and the maintenance history of the remaining heads. Then, while printing on the print medium is stopped, cleaning is performed on the designated head and the additional head. In this way, by cleaning the additional head selected based on the cleaning-related information in an inkjet printing device together with the designated head, advantages for the printing device (such as improved printing efficiency and quality) can be obtained compared to cleaning only the designated head. Furthermore, the additional head is automatically selected based on cleaning-related information, including printer-specific information, information related to the print job, the ejection operation history, and the maintenance history. Therefore, the additional heads to be included in the cleaning target can be appropriately selected without depending on the skill level of the person.

[0020] For example, the present invention No. 2 According to this aspect, a print head that, when included among the remaining heads as a cleaning target, requires less time for cleaning than the time required for cleaning only the designated head, is selected as the additional head, and the shortened cleaning time improves printing efficiency (throughput).

[0021] Also, for example, FourthAccording to this aspect, when cleaning is performed on only the designated head among the remaining heads, the print head whose condition deteriorates due to drying is selected as the additional head, so the condition of the print head is maintained in good condition, the frequency of cleaning is reduced, and high printing efficiency and quality can be maintained.

[0022] The present invention also No. 5 According to this aspect, after cleaning is performed on the designated head, an additional head is selected according to the printing conditions of the print job to be printed, so that the next job is printed in accordance with those printing conditions (paper width, paper type, required print quality, etc.), thereby maintaining high printing efficiency and quality.

[0023] The present invention also No. 6 According to this aspect, an additional head is selected based on information indicating the history of at least one of maintenance, ejection operation, and ejection defect inspection for each of the plurality of print heads, so that the condition of each print head is maintained in good condition, the frequency of cleaning is reduced, and high printing efficiency and quality can be maintained.

[0024] The present invention also Seventh According to this aspect, when the printing unit includes print heads of different colors and the cleaning mechanism is configured to be able to clean print heads of the same color as a unit, an additional head is selected from the remaining heads within a range that does not make the cleaning time longer than the print head of the color that requires the longest cleaning time among the designated heads. This allows the condition of each print head to be maintained in good condition in an inkjet printing device capable of color printing, reducing the frequency of cleaning and enabling high printing throughput to be maintained.

[0025] The present invention also No. 8 According to this aspect, the same effects as those of the first aspect of the present invention can be obtained.

[0026] The effects of other aspects of the present invention are clear from the explanation of the effects of the above aspects of the present invention and the effects of the following embodiment and its modifications, and therefore will not be explained here. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a diagram illustrating the overall configuration of a printing system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of the configuration of an inkjet printing apparatus according to the embodiment. [Figure 3] FIG. 2 is a plan view showing an example of the configuration of a printing unit in the embodiment. [Figure 4] FIG. 2 is a block diagram showing a hardware configuration of the print control device in the embodiment. [Figure 5] FIG. 2 is a block diagram showing a schematic functional configuration of a control unit in the embodiment. [Figure 6] FIG. 2 is a block diagram showing a schematic configuration of a part related to cleaning in a main control unit in the embodiment. [Figure 7] FIG. 2 is a block diagram showing a detailed configuration of a part related to cleaning in the main control unit in the embodiment. [Figure 8] 10 is a flowchart illustrating an example of a maintenance operation procedure in the embodiment. [Figure 9] 10 is a flowchart illustrating an example of a cleaning process in the embodiment. [Figure 10] FIG. 10 is a schematic diagram for explaining a case where the time required for cleaning is shortened by adding a head to be cleaned in the embodiment. [Figure 11] 10 is a flowchart for explaining a modified example of the selection of additional heads based on condition 1 in the selection of additional heads in the cleaning process shown in FIG. 9. [Figure 12] FIG. 2 is a top view conceptually showing a printing unit and paper in the embodiment. [Figure 13]FIG. 2 is a side view conceptually showing a printing unit and a cleaning mechanism in the embodiment. [Figure 14] 10A and 10B are schematic diagrams for explaining a target to be cleaned when the paper width is changed in the embodiment. [Figure 15] 10 is a flowchart for explaining a modified example of the selection of additional heads based on condition 5 in the selection of additional heads in the cleaning process shown in FIG. 9. [Figure 16] 10 is a flowchart showing a procedure for automatically starting cleaning in another example of the cleaning process in the embodiment. [Figure 17] 10 is a flowchart showing a procedure for manually starting cleaning in another example of the cleaning process in the embodiment. [Figure 18] 10 is a flowchart showing the procedure of a cleaning execution process in another example of the cleaning process in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0029] <1. Overall configuration of the printing system> FIG. 1 is a diagram illustrating the overall configuration of a printing system according to an embodiment of the present invention. This printing system comprises an inkjet printing device 10 and a print data generating device 40. The inkjet printing device 10 and the print data generating device 40 are connected to each other via a communication line 5. The print data generating device 40 generates print data by performing RIP processing and the like on input data such as a PDF file. The print data generated by the print data generating device 40 is transmitted to the inkjet printing device 10 via the communication line 5. The inkjet printing device 10 outputs a print image on printing paper as a print medium based on the print data transmitted from the print data generating device 40. The inkjet printing device 10 comprises a printing machine main body 200, a print control device 100 that controls the operation of the printing machine main body 200, and an image inspection device 300 that inspects the print state. In other words, this inkjet printing device 10 is a printing device with an inspection function. Some components of the image inspection device 300 are built into the printing machine main body 200.

[0030] 1, the image inspection device 300 is one component of the inkjet printing device 10 (i.e., the image inspection device 300 is included in the inkjet printing device 10), but this is not limiting. The image inspection device 300 may also be a device independent of the inkjet printing device 10.

[0031] <2. Configuration of inkjet printing device> 2 is a schematic diagram showing an example of the configuration of the inkjet printing apparatus 10. As described above, the inkjet printing apparatus 10 is made up of the print control device 100, the printing press main body 200, and the image inspection device 300.

[0032] The printing press main body 200 includes a paper feed unit 21 that supplies printing paper (e.g., roll paper) PA as a printing medium, a printing mechanism 20 that performs printing on the printing paper PA, and a paper take-up unit 28 that takes up the printing paper PA after printing. The printing mechanism 20 includes a first drive roller 22 that transports the printing paper PA inside the printing mechanism 20, a plurality of support rollers 23 that transport the printing paper PA inside the printing mechanism 20, a printing unit 24 that ejects ink onto the printing paper PA to perform printing, a cleaning mechanism 25 that cleans the printing unit 24 (for example, purging by suctioning ink from the nozzles and wiping the nozzle surfaces, as described below), a drying unit 26 that dries the printing paper PA after printing, an imaging unit 310 that captures an image of the printed image (the printing paper PA after printing), and a second drive roller 27 that outputs the printing paper PA from inside the printing mechanism 20. The imaging unit 310 is a component of the image inspection device 300 and is configured using an image sensor such as a CCD or CMOS.

[0033] The print control device 100 controls the operation of the printing press main body 200 configured as described above. When a print output instruction command is given to the print control device 100, the print control device 100 controls the operation of the printing press main body 200 so that the print paper PA is transported from the paper delivery unit 21 to the paper take-up unit 28. While the print paper PA is being transported in this manner, first the printing unit 24 prints on the print paper PA, then the drying unit 26 dries the print paper PA, and finally the imaging unit 310 captures an image of the print image. In addition, the cleaning mechanism 25 cleans the printing unit 24 as needed.

[0034] The image inspection device 300 is composed of an imaging unit 310 and an image inspection computer 320. Captured image data Di obtained by capturing an image of a print image with the imaging unit 310 is sent to the image inspection computer 320. The image inspection computer 320 performs an inspection to detect defects (faults) by performing image analysis on the captured image data Di. Note that the method is not limited to this. Inspection to detect defects (faults) may be performed by comparing the captured image data Di with the print data Dp transmitted from the print data generating device 40. Furthermore, an inspection pattern may be printed using prepared inspection image data Dc, and the captured image data Di obtained by capturing the print image may be compared with the inspection image data Dc to detect defects (faults). The inspection result Dr obtained by the image inspection computer 320 is sent to the print control device 100.

[0035] FIG. 3 is a plan view showing an example of the configuration of the printing unit 24. As shown in FIG. 3, the printing unit 24 is composed of print head arrays 240C, 240M, 240Y, and 240K of C (cyan), M (magenta), Y (yellow), and K (black) colors, arranged in the transport direction of the print paper PA. Each print head array is composed of multiple print heads 241 arranged in a staggered pattern. Each print head 241 includes a large number of nozzles that eject ink. Each nozzle of the print head 241 in the C print head array 240C ejects C ink, each nozzle of the print head 241 in the M print head array 240M ejects M ink, each nozzle of the print head 241 in the Y print head array 240Y ejects Y ink, and each nozzle of the print head 241 in the K print head array 240K ejects K ink.

[0036] While the configuration of the inkjet printing device 10 that performs color printing has been exemplified here, the present invention can also be applied to inkjet printing devices that perform monochrome printing. Furthermore, while the configuration of the inkjet printing device 10 that uses aqueous ink has been exemplified here, the present invention can also be applied to inkjet printing devices that use UV ink (ultraviolet-curable ink), such as inkjet printing devices for label printing. As described above, there are no particular limitations on the type of printing device as long as it is equipped with a printing unit that requires cleaning.

[0037] <3. Hardware configuration of print control device> FIG. 4 is a block diagram showing the hardware configuration of the print control device 100. As shown in FIG. 4, the print control device 100 is a computer including a main body 110, an auxiliary storage device 121, an optical disk drive 122, a display unit 123, a keyboard 124, and a mouse 125. The main body 110 includes a CPU 111, a memory 112, a first disk interface unit 113, a second disk interface unit 114, a display control unit 115, an input interface unit 116, an output interface unit 117, and a network interface unit 118. The CPU 111, the memory 112, the first disk interface unit 113, the second disk interface unit 114, the display control unit 115, the input interface unit 116, the output interface unit 117, and the network interface unit 118 are connected to one another via a system bus. The auxiliary storage device 121 is connected to the first disk interface unit 113. The optical disk drive 122 is connected to the second disk interface unit 114. A display unit (display device) 123 is connected to the display control unit 115. A keyboard 124 and a mouse 125 are connected to the input interface unit 116. The printing machine main body 200 is connected to the output interface unit 117 via a communication cable. A communication line 5 is connected to the network interface unit 118. The auxiliary storage device 121 is a magnetic disk device or the like. An optical disk 6 serving as a computer-readable recording medium such as a CD-ROM or DVD-ROM is inserted into the optical disk drive 122. The display unit 123 is a liquid crystal display or the like. The display unit 123 is used to display information desired by the user. The keyboard 124 and mouse 125 are used as operation units for the user to input instructions to this printing control device 100.

[0038] The auxiliary storage device 121 stores a print control program P (a program for controlling the execution of print processing by the printing press main body 200). The CPU 111 reads the print control program P stored in the auxiliary storage device 121 into the memory 112 and executes it, thereby realizing various functions of the print control device 100. The memory 112 includes RAM and ROM. The memory 112 functions as a work area for the CPU 111 to execute the print control program P stored in the auxiliary storage device 121. The print control program P is provided by being stored in the computer-readable recording medium (non-transitory recording medium). That is, for example, a user purchases an optical disc 6 as a recording medium for the print control program P, inserts it into the optical disc drive 122, reads the print control program P from the optical disc 6, and installs it in the auxiliary storage device 121. Alternatively, the print control program P transmitted via the communication line 5 may be received by the network interface unit 118 and installed in the auxiliary storage device 121.

[0039] <4. Control Unit> <4.1 General configuration> 5 is a block diagram showing a schematic functional configuration of the control unit 150 that is realized by executing the print control program P on the print control device 100. The control unit 150 is made up of a main control unit 151, a drying control unit 154, and an inspection control unit 155, and the main control unit 151 includes a maintenance content determination unit 152 and a print control unit 153.

[0040] The maintenance content determination unit 152 determines the content of maintenance for each print head (hereinafter simply referred to as "head") 241 in the printing unit 24 based on the results of inspection by the image inspection device 300 (the inspection results Dr obtained by the image inspection computer 320). As will be described later, this maintenance content determination unit 152 determines whether cleaning is necessary when maintenance is required, and if cleaning is to be performed, determines the print head 241 to be cleaned. For this purpose, the maintenance content determination unit 152 includes a cleaning activation unit 161 and an additional head selection unit 162.

[0041] The print control unit 153 controls the print unit 24 and the transport mechanism 210. As described above, the print unit 24 is made up of multiple print heads (inkjet heads) 241, and each print head 241 includes a large number of nozzles (see FIG. 3). In this embodiment, the transport mechanism 210 is realized by the paper feed unit 21, the first drive roller 22, multiple support rollers 23, the second drive roller 27, and the paper winding unit 28 (see FIG. 2). When maintenance is performed on the print unit 24, the print control unit 153 controls the operation of the print unit 24 and the cleaning mechanism 25 in accordance with the maintenance content determined by the maintenance content determination unit 152.

[0042] The drying control unit 154 controls the temperature (drying temperature) when the drying unit 26 dries the print paper PA. The inspection control unit 155 controls the timing at which the imaging unit 310 captures the print image.

[0043] <4.2 Configuration of cleaning-related parts in the main control> 6 is a block diagram showing a schematic configuration of cleaning-related parts of the main control unit 151 in this embodiment. The main control unit 151 includes, as components of the cleaning-related parts, a cleaning activation unit 161, an additional head selection unit 162, a cleaning execution control unit 163, and a print execution control unit 165. The cleaning execution control unit 163 and the print execution control unit 165 constitute the print control unit 153 described above.

[0044] The cleaning activation unit 161 determines whether cleaning is necessary at a predetermined timing described below. If cleaning is necessary, it determines the print head to be cleaned (hereinafter referred to as the "designated head"), i.e., the target to be cleaned, and outputs a cleaning start instruction Ics. When the cleaning start instruction Ics is output, the additional head selection unit 162 selects an additional print head to be cleaned (hereinafter referred to as the "additional head"). When an additional head is selected, the cleaning execution control unit 163 controls the cleaning mechanism 25 so that the cleaning mechanism 25 cleans the designated head and the additional head among the print heads 241 in the printing unit 24. Meanwhile, when printing is performed based on print data Dp from the print data generation device 40, the print execution control unit 165 controls the printing unit 24 and the transport mechanism 210 so that the print image indicated by the print data Dp is formed on the print paper PA, and when the cleaning start instruction Ics is output, it causes the transport mechanism to stop transporting the print paper PA (if transport of the print paper PA is stopped at the time the cleaning start instruction Ics is output, that stopped state is maintained).

[0045] 7 is a block diagram showing the detailed configuration of cleaning-related portions of the main control unit 151 in this embodiment. In addition to the cleaning activation unit 161, additional head selection unit 162, and cleaning execution control unit 163 described above, the main control unit 151 also includes an inspection result storage unit 156 and a cleaning-related information storage unit 157. As shown in FIG. 7, the cleaning activation unit 161 also includes a missing nozzle determination unit 171, a cleaning target head determination unit 172, a UI display unit 173, a UI operation unit 174, and a cleaning instruction reception unit 175.

[0046] The inspection result holding unit 156 holds the inspection results Dr sent from the image inspection computer 320. The maintenance content determination unit 152 uses missing information LI, which is the inspection result related to missing nozzles (defects) and the like, from the inspection results Dr sent from the image inspection computer 320. In the cleaning activation unit 161, the missing nozzle determination unit 171 determines the extent of missing nozzles for each print head based on this missing information LI, and the cleaning target head determination unit 172 determines whether cleaning is necessary and determines the designated head, which is the print head to be cleaned, from among the print heads in the printing unit 24. When it is determined that cleaning is necessary and the designated head to be cleaned is determined, information indicating this is sent from the cleaning target head determination unit 172 to the cleaning instruction reception unit 175 as a cleaning instruction.

[0047] On the other hand, in this embodiment, the user can also determine whether cleaning is necessary and specify the print head to be cleaned using the UI display unit 173 and the UI operation unit 174. That is, the UI display unit 173 displays information that combines the above-mentioned missing information LI or the above-mentioned missing information LI with cleaning history information and ejection operation history information of each print head 241, and the user can view the information displayed on the UI display unit 173 and specify the print head to be cleaned by inputting information to the UI operation unit 174. When the user determines that cleaning is necessary and specifies the specified head to be cleaned, information indicating this is sent from the UI operation unit 174 to the cleaning instruction reception unit 175 as a cleaning instruction.

[0048] When the cleaning instruction receiving unit 175 receives a cleaning instruction from the cleaning target head determination unit 172 or the UI operation unit 174, it outputs a cleaning start instruction Ics together with information indicating the designated head. This cleaning start instruction Is is sent to the additional head selection unit 162. As mentioned above, this cleaning start instruction Is is also sent to the print execution control unit 165 (see FIG. 6).

[0049] When the additional head selection unit 162 receives the cleaning start command Ics, it selects an additional print head to be cleaned from among the print heads other than the designated head in the printing unit 24 (hereinafter referred to as "remaining heads"), based on the information stored in the cleaning-related information storage unit 157. Information indicating the selected additional head is sent to the cleaning execution control unit 163 together with information indicating the designated head.

[0050] The information held in the cleaning-related information holding unit 157 (hereinafter referred to as "cleaning-related information") is information useful for determining whether each print head 241 should be cleaned, and is information other than the missing information LI. In this embodiment, the cleaning-related information stored in the cleaning-related information holding unit 157 includes ejection operation history, maintenance history (including history of ejection defect inspections), job information related to print jobs (information related to the next job, etc.), and printing press-specific information (information indicating the configuration of cleaning-related parts such as the printing unit 24 and functions related to cleaning). However, the cleaning-related information to be used for selecting additional heads is not limited to these. Of this cleaning-related information, history information is updated in the control unit 150 as printing operations and maintenance operations (including cleaning operations) are performed. The selection of additional heads will be described in detail below.

[0051] The cleaning mechanism 25 is configured to be able to selectively clean the multiple print heads 241 in the printing unit 24. Based on information sent from the additional head selection unit 162, the cleaning execution control unit 163 controls the cleaning mechanism 25 so that the cleaning mechanism 25 cleans the designated head and the additional heads among the print heads 241 in the printing unit 24. Note that the cleaning mechanism 25 in this embodiment is configured not only to clean each print head individually, but also to be able to clean multiple print heads (for example, multiple print heads of the same color) as a group all at once.

[0052] 5. Maintenance control In the inkjet printing apparatus 10 according to this embodiment, maintenance of the printing unit 24 is performed based on the results of inspection by the image inspection device 300. In this regard, in this embodiment, after printing based on each job is completed, a process is performed to determine whether maintenance is necessary and the type of maintenance (hereinafter referred to as a "maintenance content determination process"). Thereafter, the operation of the printing unit 24 and cleaning mechanism 25 is controlled by the print control unit 153 according to the results of the maintenance content determination process, thereby performing the desired maintenance of the printing unit 24.

[0053] FIG. 8 is a flowchart illustrating an example of a maintenance procedure according to this embodiment. Each time the inkjet printing device 10 receives print data corresponding to submitted data from the print data generating device 40, the inkjet printing device 10 registers a print job (hereinafter simply referred to as a "job") by storing the print data along with job information in the auxiliary storage device 121 within the print control device 100 (see FIGS. 1 and 4). The job information includes printing condition data indicating various conditions (e.g., resolution, paper size, number of sheets, etc.) that should be set during printing. In this embodiment, multiple jobs can be continuously accepted, and the accepted multiple jobs are processed sequentially in the order they are accepted. During this process, the CPU 111 in the print control device 100 executes the process shown in the flowchart of FIG. 8. That is, the CPU 111 operates as follows based on the print control program P.

[0054] When each job is processed, the operation of the transport mechanism 210 is controlled so that the transport of the print paper PA, which is currently stationary, begins. The transport speed gradually increases, and when it reaches a preset reference speed (a speed suitable for printing), it is maintained constant at that reference speed. While the transport speed is maintained at the reference speed (i.e., while the print paper PA is being transported at a constant speed), the operation of the printing unit 24 is controlled so that printing according to the print data of that job is performed on the print paper PA.

[0055] In this way, the first job of the plurality of jobs is executed first, that is, printing is performed according to the print data Dp of the first job (step S102).

[0056] When this job is completed, the printing unit 24 and the transport mechanism 210 are controlled so that a predetermined test pattern is printed on the print paper PA, and the ejection state of each print head 241 is detected based on the printed image of the test pattern (step S104). That is, under the control of the CPU 111, the imaging unit 310 captures the printed image of the test pattern, and the image inspection computer 320 performs image analysis on the captured image data Di obtained by capturing the image. The results of this image analysis are stored as the inspection result Dr in the auxiliary storage device 121 or memory 112, which is the inspection result storage unit 156.

[0057] Next, based on the defect information LI, which is the inspection result regarding defects (faults) such as nozzle defects, among the inspection results Dr, it is determined whether maintenance is necessary (step S106). If the result of this determination is that maintenance is not necessary, the process proceeds to step S114, and if maintenance is necessary, it is determined whether cleaning is necessary based on the defect information LI (step S108).

[0058] As described above, the necessity of cleaning may be determined automatically by the CPU 111, i.e., by the nozzle missing determination unit 171, which is realized in software when the CPU 111 executes a predetermined routine in the print control program P, or may be determined and instructed manually by the user, i.e., the user may instruct whether cleaning is necessary by inputting information displayed on the display unit 123 using the keyboard 124 or mouse 125 (see FIG. 7). In the latter case, the necessity of cleaning is instructed by the user using the UI display unit 173 and UI operation unit 174, which are realized in software when the CPU 111 executes another predetermined routine in the print control program P.

[0059] If it is determined in step S108 that cleaning is not required (including when an instruction to not require cleaning is given), maintenance other than cleaning, such as flushing, is performed (step S110), and then the process proceeds to step S114. On the other hand, if it is determined in step S110 that cleaning is required (including when an instruction to not require cleaning is given), the printing unit 24 and the transport mechanism 210 are controlled to stop the printing operation (if the printing operation was stopped when it was determined that cleaning was required, the stopped state is maintained) (step S111), and a cleaning process is performed (step S112). When the cleaning process is completed, the system is set to a state where printing is possible (step S113), and the process proceeds to step S114.

[0060] In step S114, it is determined whether or not there is a next job based on information (job information) related to the job registered in the auxiliary storage device 121. If the result of this determination shows that there is a next job, the process returns to step S102, and the processes from step S102 onwards are executed for the next job; if there is no next job, the printing operation is terminated.

[0061] 5.1 Example of cleaning process Fig. 9 is a flowchart showing an example of the cleaning process in this embodiment, and shows the procedure of the cleaning process in step S112 in the flowchart of Fig. 8. In this cleaning process, the CPU 111 operates as follows based on a predetermined routine in the print control program P.

[0062] First, it is determined whether the start of the cleaning process was due to an input operation by the user (step S122). If it was due to an input operation by the user, the process proceeds to step S126, where information that serves as a basis for determining the designated head, which is the print head to be cleaned, is displayed on display unit 123 (UI display unit 173) (step S126). In this example, the above-mentioned missing information LI that indicates the ejection status of each print head 241 is displayed on display unit 123 as the basis for this determination. When the user determines the designated head to be cleaned based on this missing information and performs an input operation to indicate the designated head, the input operation is accepted (step S128).

[0063] If the result of the determination in step S122 is that the start of the cleaning process was not due to an input operation by the user, the designated head, which is the print head to be cleaned, is determined (step S124) based on the missing information LI that indicates the ejection status of each print head 241. In other words, the CPU 111 automatically determines the designated head through software processing.

[0064] Once the designated head to be cleaned is determined in step S124 or S128 as described above, the printing unit 24 selects, as additional heads, print heads other than the designated head (remaining heads) to be cleaned together with the designated head, based on the cleaning-related information stored in the auxiliary storage device 121 (which serves as the cleaning-related information storage unit 157) (see FIG. 7) (step S130). The additional heads are selected based on whether or not the inkjet printing device will benefit from being cleaned together with the designated head. Essentially, the selection is based on whether or not the printing throughput or quality of the printing device will be improved by including the additional head as a cleaning target. Specifically, in this embodiment, the additional heads to be added to the remaining heads to be cleaned are selected based on each of the following conditions 1 to 5, and the union of the additional heads based on each condition n (n = 1 to 5) is determined as the target additional head. The cleaning-related information is composed of information for determining whether or not each of the following conditions 1 to 5 is satisfied.

[0065] (Condition 1): A print head that requires less cleaning time when it is cleaned together with a designated head than when it is cleaned only with a designated head. (Condition 2): Print heads whose ejection condition deteriorates due to drying when cleaning is performed for only the specified heads (Condition 3): Print heads to be added to the cleaning target for printing that meets the printing conditions of the job to be executed after the cleaning to be started is completed (Condition 4): For each print head, a print head that should be added to the cleaning target based on at least one of the histories of maintenance, ejection operation, and ejection failure inspection. (Condition 5): If the printing unit includes print heads of different colors and the cleaning mechanism is configured to be able to clean print heads of the same color as a unit, the print heads that can be added to the cleaning target within a range that does not extend beyond the cleaning time required for the designated head of the color that requires the longest cleaning time among the designated heads.

[0066] (1) Selection of additional heads based on condition 1 When adding a print head that satisfies condition 1 from among the remaining heads to the list of cleaning targets, it is necessary to store in advance as printer-specific information information about the configuration and functions related to cleaning in the inkjet printing device 10, such as the number and arrangement of print heads 241 in the printing unit 24, and the relationship between cleaning control modes and required time. This is because whether adding a print head to the list of cleaning targets will shorten the required cleaning time depends on the configuration and functions related to cleaning that are specific to the printing machine.

[0067] For example, as shown in FIG. 10, the cleaning mechanism 25 may be configured to switch between a mode in which ink suction (purging) to unclog nozzles in the print heads is performed for each print head individually and a mode in which ink purging is performed for multiple print heads at once. In this case, the time required for cleaning may be shorter if the purging is performed for multiple print heads at once rather than individually. In the example shown in FIG. 10, the cleaning mechanism 25 includes caps CP1-CP3 facing the print heads HD1-HD3, corresponding valves VL1-VL3 connected to the caps CP1-CP3, a single valve 4 commonly connected to the caps CP1-CP3, and a pump PM connected to the valves 1-4. The cleaning mechanism 25 has a flow path for individually suctioning ink from each print head HDi (i = 1-3) via the corresponding cap CPi and valve VLi using the pump PM, and a flow path for collectively suctioning ink from all three print heads HD1-HD3 via the valve 4 using the pump PM. In this example, the time required for cleaning purge is shorter if the ink from the three print heads HD1 to HD3 is sucked out all at once via valve 4 than if the ink from the two print heads HD1 and HD2 is sucked out individually via valves VL1 and VL2, respectively.

[0068] In this embodiment, the information used to determine whether adding a print head to be cleaned will shorten the time required for cleaning, i.e., the above-mentioned printing press-specific information, is stored in advance as part of the cleaning-related information in the auxiliary storage device 121. The portion of the auxiliary storage device 121 that stores the cleaning-related information corresponds to the cleaning-related information storage unit 157 in the functional block diagram shown in FIG.

[0069] Although adding a print head to be cleaned does not shorten the time required for cleaning, if adding a certain print head does not increase the time required for cleaning and improves the condition of that print head, thereby improving printing efficiency or quality, then that print head may be selected as an additional head based on condition 1.

[0070] On the other hand, since the inkjet printing device 10 is in a state where printing operations are stopped during the cleaning operation, it is preferable to be able to change the selection of additional heads based on condition 1 when the user is concerned about time or when the printing work needs to be rushed. FIG. 11 is a flowchart for explaining an example of a configuration for this, and shows a modified example of the selection of additional heads based on condition 1 in the selection of additional heads in the cleaning process shown in FIG. 9. As shown in FIG. 11, in this modified example, an additional head based on condition 1 is selected from the remaining heads using printing machine-specific information as cleaning-related information (step S202), and then the selected additional head is displayed on the display unit 123 (step S204), and the user can instruct by inputting using keyboard 124 or mouse 125 whether or not to include the additional heads shown on display unit 123 in the cleaning targets (step S206). That is, in this modified example, when selecting the remaining heads to be included in the cleaning targets based on condition 1, rather than simply including the remaining heads selected based on the cleaning-related information in the cleaning targets, a UI display unit and UI operation unit are provided for the user to instruct whether or not to accept the addition of the selected print head to the cleaning targets (steps S204, S206). If an input operation instructing to accept the addition to the cleaning targets is accepted, the selected print head is treated as an added head based on condition 1 (step S210), and if an input operation instructing not to accept the addition to the cleaning targets is accepted, the selected print head is not included in the added heads (step S212), and the set of added heads based on condition 1 becomes empty.

[0071] Note that even when a print head (additional head) to be included in the cleaning target among the remaining heads is selected based on any of conditions 2 to 5, a UI display unit or UI operation unit may be provided to enable such user instructions. In such a configuration, if an input operation is received to instruct not to accept the addition of an additional head selected based on any of conditions 1 to 5 to the cleaning target, the additional head for which the instructed not to accept is excluded from the additional heads to be cleaned by cleaning mechanism 25. In this case, cleaning is performed on additional heads other than the selected additional head (additional heads selected based on conditions other than the selected condition) and the specified head.

[0072] (2) Selection of additional heads based on condition 2 When the width of the print paper PA (hereinafter simply referred to as "paper width") is narrower than the width of the print head row (see "preceding job" in Figure 14 below), there will be print heads that do not eject ink during printing. In this case, forcibly performing maintenance on print heads that do not eject ink can maintain their condition better. On the other hand, when determining the designated print heads to be cleaned based on the missing information LI obtained from the image of the test pattern printed on the print paper PA (see 172 in Figure 7 and S124 in Figure 9), print heads located outside the paper width do not eject ink, so information indicating the ejection status, such as missing information LI, cannot be obtained for those print heads. However, when the width of the print head row is narrower than the paper width, additional heads based on condition 2 are selected using job information from the cleaning-related information, and print heads that are not undergoing cleaning such as purging in a decapped state can also be targeted for cleaning. This maintains the condition of those print heads in good condition and reduces the frequency of cleaning, thereby maintaining high print throughput and quality.

[0073] This will be explained more specifically with reference to FIG. 12 and FIG. FIG. 12 is a conceptual top view of the printing unit 24 and print paper PA, and FIG. 13 is a conceptual side view of the printing unit 24 and cleaning mechanism 25. As shown in FIG.

[0074] As shown in Figure 12, the printing unit 24 is disposed above the print paper PA. The printing unit 24 includes a head holding plate 240 and multiple print heads 241 (first print head 241a to fourth print head 241d) that are juxtaposed in the paper width direction X of the print paper PA and attached to the underside of the head holding plate 240. The print paper PA is transported in the transport direction Y. The direction perpendicular to the paper width direction X and the transport direction Y is the up-down direction Z.

[0075] The printing unit 24 can move between a printing position P1 directly above the print paper PA and a cleaning position P2 spaced apart from the printing position P1 in the paper width direction X. Although not shown in Figure 12, a cleaning mechanism 25 is disposed below the printing unit 24 at the cleaning position P2.

[0076] The printing unit 24 can print on print paper PA with a width W10, which corresponds to the length of the first print head 241a through fourth print head 241d in the paper width X direction. However, print paper PA with a narrow width W11 narrower than width W10 may also be used. When printing on print paper PA with narrow width W11, the first print head 241a through third print head 241c are used for printing, and the fourth print head 241d is not used for printing.

[0077] FIG. 13 is a conceptual side view of the printing unit 24 and cleaning mechanism 25, viewed from the "-Y" direction, opposite the transport direction Y of the print paper PA. The cleaning mechanism 25 has multiple caps 251 (first cap 251a to fourth cap 251d) placed on the upper surface of a holding plate 250. The first cap 251a to fourth cap 251d correspond to the first print head 241a to fourth print head 241d, respectively. The cleaning mechanism 25 can be raised and lowered between a cap height, at which the cap 251 caps the print head 241, and a decap height, at which the cap 251 is separated from the print head 241 a small distance below the cap height. At the cap height, the cap 251 caps the print head 241, preventing the nozzles of the print head 241 from drying out. At the decap height, the print head 241 purges ink droplets toward the cap 251 to clean the print head 241. Alternatively, cleaning may be performed by wiping the nozzle surface of the print head 241 with a wiper (not shown). In Figure 13, the cleaning mechanism 25 is located at the decap height.

[0078] Typically, after printing on narrow width W11 print paper PA, the first through third print heads 241a through 241c are cleaned by the cleaning mechanism 25. However, as shown in FIG. 13, while the first through third print heads 241a through 241c are being cleaned, the fourth print head 241d, which is not the target of cleaning, is left in a decapped state. Therefore, if the cleaning period for the designated heads, the first through third print heads 241a through 241c, is expected to be longer than the drying time of the undesignated fourth print head 241d, the fourth print head 241d is selected as an additional head. In other words, cleaning (purging) of the fourth print head 241d is performed in parallel with cleaning (purging) of the first through third print heads 241a through 241c. Conversely, if the cleaning period for the designated heads, first print head 241a through third print head 241c, is expected to be shorter than the drying time for the undesignated fourth print head 241d, the fourth print head 241d is not selected as an additional head and cleaning is not performed. By performing this type of control, the undesignated fourth print head 241d can be maintained in good condition without unnecessarily increasing the cleaning frequency.

[0079] (3) Selection of additional heads based on condition 3 By selecting additional printheads to be cleaned to match the printing conditions (paper width, paper type, print quality requirements, etc.) of the next job, which is the print job to be executed after the cleaning to be started, as additional heads, the condition of each printhead is maintained in good condition and the frequency of cleaning is reduced, thereby maintaining high print throughput and quality. For example, as shown in Figure 14, if the paper width W2 of the next job is wider than the paper width W1 of the preceding job, which is the print job immediately before the cleaning to be started, the next job will use printheads that were not used in the preceding job. In this case, by selecting additional heads based on condition 3 using job information (more specifically, information indicating the printing conditions of the next job) as cleaning-related information, such printheads can be included in the cleaning target, thereby enabling the next job to be executed smoothly and preventing a decline in print throughput and quality. Furthermore, if the print quality requirements for the next job are higher than those for the preceding job, or if the tolerance for missing nozzles in the next job is lower than that for the preceding job, the job information as cleaning-related information can be used to select additional heads based on condition 3, thereby successfully executing the next job and preventing a decline in print throughput and quality. In this case, the determination level by the missing nozzle determination unit 171 in the cleaning activation unit 161 can be changed to a stricter level based on the next job information.

[0080] (4) Selection of additional heads based on condition 4 By using the ejection operation history and maintenance history as cleaning-related information to select as additional heads from among the remaining heads a print head to be added to be cleaned based on condition 4, the condition of each print head is maintained in good condition and the frequency of cleaning is reduced, thereby making it possible to maintain high printing throughput and quality. In this embodiment, for example, of the remaining heads, the following print heads (a) to (f) are selected as additional heads based on condition 4. In this case, the cleaning-related information storage unit 157 is used as a history information storage unit. (a) A print head that has been cleaned for more than a specified period of time (b) A print head whose ink ejection volume or ejection operation time exceeds the upper limit or falls below the lower limit. (c) A print head for which the time elapsed since the most recent ink ejection operation exceeds a predetermined time. (d) A print head in which the frequency of detection of missing nozzles exceeds a predetermined value. (e) A print head whose total number of ejections and / or total ejection time exceeds the upper limit (f) A print head that has a lot of mist or other foreign matter adhering to it from the upstream head or surrounding heads at the same position on the transport path.

[0081] (5) Selection of additional heads based on condition 5 If the printing unit 24 includes print heads of different colors and the cleaning mechanism is configured to be able to clean print heads of the same color as a unit, a print head that can be added to the cleaning target, provided that the cleaning time is not longer than the cleaning time required for the designated head of the color that requires the longest cleaning among the designated heads, is selected as an additional head based on condition 5. Therefore, printing-machine-specific information including information indicating the configuration of the printing unit 24 and the cleaning mechanism 25 is used to select such an additional head. By selecting an additional head based on condition 5 in an inkjet printing device capable of color printing, the condition of each print head is maintained in good condition and the frequency of cleaning is reduced, thereby enabling high printing throughput to be maintained.

[0082] However, selecting an additional head based on condition 5 may result in excessive ink consumption. Therefore, if reducing ink consumption is important, it is preferable to allow the user to specify additional conditions to be added to condition 5 to limit the increase in ink consumption caused by the additional head selected based on condition 5. For example, it is preferable to select an additional head based on condition 5 using the procedure shown in FIG. 15 . In the example shown in FIG. 15 , first, an operation screen for specifying additional conditions to be added to condition 5 (hereinafter simply referred to as “additional conditions”) is displayed on the display unit 123 (step S222), and input operations to specify the additional conditions are accepted on the operation screen using the keyboard 124 or mouse 125 (step S224). Next, of the remaining heads, print heads that satisfy the additional conditions in addition to condition 5 are selected as additional heads based on printing-press-specific information as cleaning-related information (step S226). This configuration for selecting an additional head based on condition 5 can prevent excessive ink consumption by appropriately setting the additional conditions. In step S222, it is preferable to display on the display unit 123 conditions that can be added to condition 5, such as the upper limit on the number of additional heads and the upper limit on the amount of ink consumed per unit time (estimated value), as well as information that provides useful information and hints to enable the user to specify appropriate additional conditions.

[0083] As can be seen from the above explanation, of the components of main control unit 151 shown in Figures 5 to 7, maintenance content determination unit 152 is realized by steps S104 to S108 of Figure 8 and steps S122 to S128 of Figure 9, cleaning activation unit 161 is realized by step S108 of Figure 8 and steps S122 to S128 of Figure 9, UI display unit 173 and UI operation unit 174 are realized by steps S126 and S128 of Figure 9, respectively, missing nozzle determination unit 171 and cleaning target head determination unit 172 are realized by step S124 of Figure 9, additional head selection unit 162 is realized by step S130 of Figure 9, and cleaning execution control unit 163 is realized by step S132 of Figure 9.

[0084] <5.2 Other examples of cleaning treatment> In this embodiment, the CPU 111 may automatically determine whether cleaning is necessary, i.e., the CPU 111 may determine the presence of a missing nozzle by using a software-implemented nozzle missing determination unit 171. Alternatively, the user may manually instruct cleaning, i.e., the user may instruct cleaning by inputting information displayed on the display unit 123 via the keyboard 124 or mouse 125 (see FIG. 7). The cleaning process shown in FIG. 9 corresponds to both of these cases (steps S122 to S128). In either case, the determination of whether cleaning is necessary is based on the determination of whether maintenance is necessary based on the ejection status detection results obtained from the image of the test pattern printed after each job is completed (see steps S102 to S108 in FIG. 8). However, there may be cases where the user needs to input a cleaning instruction (cleaning start instruction) at a different timing than the above. Below, a cleaning process in which the user can input a cleaning start instruction at a different timing than the above will be described with reference to FIGS. 16 to 18.

[0085] 16 to 18 are flowcharts showing another example of the cleaning process in this embodiment. In this example, the cleaning process when the CPU 111 automatically determines whether cleaning is necessary (hereinafter referred to as the "automatically started cleaning process") and the cleaning process when the user instructs the start of cleaning by input operation (hereinafter referred to as the "manually started cleaning process") are executed as two different processes that run in parallel under the operating system (hereinafter abbreviated as "OS") that runs within the print control device 100 shown in FIG. 4. Also, in this example, the cleaning execution process shown in FIG. 18 is started as a separate process from the above two processes when the inkjet printing device 10 is powered on and remains resident until the power is turned off. Note that this OS has a process management function, and system functions such as inter-process communication are provided within this OS.

[0086] FIG. 16 shows the procedure for the automatically started cleaning process, which corresponds to step S112 in FIG.

[0087] If it is determined in step S108 of Fig. 8 that cleaning is necessary, the process goes to step S111 and the cleaning process of Fig. 16 is executed. In this cleaning process, the CPU 111 operates as follows.

[0088] First, the designated head, which is the print head to be cleaned, is determined based on the ejection state detection results (specifically, the missing information LI) in step S104 of Fig. 8 (step S142). Next, a cleaning start command Ics is sent to the cleaning execution process (Fig. 18) along with information indicating the designated head (hereinafter referred to as "designated head information") (step S144). Thereafter, the process waits until a cleaning completion notification is received from the cleaning execution process (step S148). If a cleaning completion notification is received during this wait, the cleaning process routine of Fig. 16 is terminated and the process returns to the processing routine of Fig. 8, where step S113 and subsequent steps are executed.

[0089] FIG. 18 is a flowchart showing the steps of the cleaning execution process. When this cleaning execution process is started, it enters a standby state until it receives a cleaning start instruction Ics (step S162). If a cleaning start instruction Ics is transmitted during this standby state in step S144 of FIG. 16 or in step S156 of FIG. 17 (described later), it is received. At this time, the designated head information transmitted along with the cleaning start instruction Ics is received. Next, of the remaining heads other than the print head indicated by the designated head information (designated head), print heads to be cleaned together with the designated head are selected as additional heads (step S164). The details of the selection of this additional head are the same as those of the selection of the additional head in step S130 of FIG. 9. Then, cleaning is performed on the designated head and the additional head (more specifically, the target additional head, which is the union of the additional heads based on each of the above-described conditions 1 to 5) (step S166). This completes the cleaning execution process corresponding to one cleaning start instruction Ics, so it returns to step S162 and enters a standby state until it receives the next cleaning start instruction Ics.

[0090] Fig. 17 shows the procedure for manually activated cleaning processing, and this cleaning processing is executed in a different process (hereinafter referred to as a "manually activated process") that runs in parallel with the process in which the cleaning processing in Fig. 16 is executed. That is, when the user issues an instruction to start cleaning by inputting data using keyboard 124 or mouse 125, a process different from the process in which the cleaning processing in Fig. 16 is executed is newly started as a manually activated process, and the cleaning processing in Fig. 17 is executed in this manually activated process. In this cleaning processing, CPU 111 operates as follows.

[0091] First, information that will be used by the user to determine the designated print head to be cleaned is displayed on the display unit 123 (UI display unit 173) (step S152). The information that will be used here includes information indicating the cleaning history and ejection operation history of each print head 241, as well as other information that provides hints for determining whether or not to clean the print head. When the user performs an input operation to designate the designated head as the print head to be cleaned based on this information, the input operation is accepted (step S154). Next, a cleaning start instruction Ics is sent to the cleaning execution process (FIG. 18) along with information indicating the designated head (designated head information) (step S156). The process then waits until a cleaning completion notification is received from the cleaning execution process (step S158). If a cleaning completion notification is received during this wait, the cleaning process of FIG. 17, i.e., the manual startup process, is terminated.

[0092] 17, a new manually activated process for executing the cleaning process is started each time the user performs an input operation indicating a cleaning start command, and the manually activated process ends when the manually activated cleaning process ends. Note that when the manual process is started, it is assumed that the printing operation is stopped, and if printing is in progress or print paper PA is being transported at the time of the input operation indicating a cleaning start command, the input operation will not be accepted.

[0093] 5 to 7, the maintenance content determination unit 152 is realized by steps S104 to S108 in FIG. 8, steps S142 and S144 in FIG. 16, steps S152 to S156 in FIG. 17, and S162 in FIG. 18; the cleaning activation unit 161 is realized by step S108 in FIG. 8, steps S142 and S144 in FIG. 16, steps S152 to S156 in FIG. 17, and S162 in FIG. 18; The missing nozzle determination unit 171 and the head to be cleaned determination unit 172 are realized by step S142 in FIG. 16, the UI display unit 173 and UI operation unit 174 are realized by steps S152 and S154 in FIG. 17, respectively, the missing nozzle determination unit 171 and the head to be cleaned determination unit 172 are realized by step S142 in FIG. 16, the additional head selection unit 162 is realized by step S164 in FIG. 18, and the cleaning execution control unit 163 is realized by step S166 in FIG. 18.

[0094] <6. Effects> According to the present embodiment described above, from among the remaining heads—i.e., print heads other than the designated head that are selected as targets for cleaning based on the ejection state detection results (missing information LI) obtained from the printed image of the test pattern—those print heads whose addition to the cleaning target will improve printing throughput or quality are selected as additional heads, and cleaning is performed on the designated head and the selected additional heads (target additional heads). This allows for more efficient cleaning than conventional inkjet printing devices, improving printing throughput and quality. Furthermore, the additional heads are automatically selected based on cleaning-related information, including ejection operation history, maintenance history, job information, and printer-specific information. Therefore, the additional heads to be included in the cleaning target can be appropriately selected without relying on human proficiency or other factors.

[0095] <7. Variations> The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, in the inkjet printing apparatus according to the above-described embodiment, a test pattern is printed each time a job is completed, and the necessity of maintenance or cleaning is determined based on the printed image of the test pattern (see FIG. 8 ). However, the timing of determining the necessity of cleaning is not limited to this. For example, when printing is interrupted due to the printer main body 200, the necessity of cleaning may be determined based on the detection results of the ejection state (missing information LI) obtained from the printed image. Furthermore, if a test pattern is printed during the execution of a job, the necessity of maintenance or cleaning may be determined based on the inspection results of the test pattern printed closest to the interruption or stoppage of printing of the main image.

[0096] In the above embodiment, an additional head is selected based on each of the above-mentioned conditions 1 to 5, and the union of the additional heads based on each condition n (n=1 to 5) is set as the target additional head (to be cleaned). However, instead of this, one or more conditions may be selected from these conditions 1 to 5, an additional head may be selected based on each selected condition, and the union of the additional heads based on each selected condition may be set as the target additional head.

[0097] In addition, in the above embodiment, two examples of cleaning processes (the example shown in Figure 9 and the example shown in Figures 16 to 18) have been described, but a configuration in which the cleaning processes of the two examples are combined may be adopted as long as it does not deviate from the spirit of the present invention and does not cause any contradictions.

[0098] In the above embodiment, the check pattern printed by the print head is read and the print head to be cleaned is determined based on the read information. However, it is also possible to directly observe the nozzle surface of the print head with an optical element, or directly observe the flight state of ink droplets ejected from the print head with an optical element, and determine the print head to be cleaned based on the observation results. [Explanation of symbols]

[0099] 10...Inkjet printing device 24…Printing Department 25...Cleaning mechanism 100...printing control device 150...Control unit 151...Main control unit 152...Maintenance content determination unit 153...printing control unit 156...Test result storage unit 157...Cleaning-related information storage unit 161...Cleaning starter 162...Additional head selection section 163...Cleaning execution control unit 165...print execution control unit 171... Missing nozzle detection unit 172...Cleaning target head determination unit 173...UI display section 174...UI operation section 175…Cleaning Instructions Reception Desk 200...printing machine body 210...Transport mechanism 241...Inkjet head (print head) 300...Image inspection device 310...imaging unit 320...Image inspection computer

Claims

1. a transport mechanism for transporting the print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing-machine-specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; The inkjet printing device, wherein the additional head selection unit selects, as the additional head, a print head from among the remaining heads that will improve at least one of printing efficiency and quality when subjected to cleaning together with the designated head.

2. 2. The inkjet printing device according to claim 1, wherein the additional head selection unit selects as the additional head a print head from among the remaining heads to be cleaned that, when included in the cleaning target, requires a shorter cleaning time than the cleaning time required for cleaning only the designated head, based on the printing machine-specific information.

3. 2. The inkjet printing device according to claim 1, wherein the additional head selection unit selects, as the additional head, a print head from among the remaining heads that, when included in the cleaning target, will not increase the time required for cleaning from the time required for cleaning only the designated head and will improve printing efficiency or quality, based on the printing machine-specific information.

4. A transport mechanism for transporting a print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing-machine-specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; The inkjet printing device, wherein the additional head selection unit selects, as the additional head, a print head whose condition will deteriorate due to drying when cleaning of only the designated head is performed among the remaining heads.

5. 5. The inkjet printing device according to claim 4, wherein the additional head selection unit selects, from among the remaining heads, a print head that does not eject ink during printing because the size of the plurality of print heads in the width direction of the printing medium is wider than the width of the printing medium, as the additional head.

6. 5. The inkjet printing device according to claim 4, wherein the additional head selection unit selects as the additional head a print head from among the remaining heads, the print head having a size in the width direction of the printing medium that is wider than the width of the printing medium, and therefore in which ejection defects cannot be detected by printing a test pattern for detecting ejection defects.

7. A transport mechanism for transporting a print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing-machine-specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; The inkjet printing device, wherein the additional head selection unit selects the additional head based on information about the print job and in accordance with printing conditions of the print job to be printed after cleaning is performed on the designated head.

8. The inkjet printing apparatus according to claim 7 , wherein the additional head selection unit selects the additional head in accordance with the width of the printing medium specified by the printing conditions.

9. The inkjet printing apparatus according to claim 7 , wherein the additional head selection unit selects the additional head in accordance with a print quality specified by the printing conditions.

10. A transport mechanism for transporting a print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing machine specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; a history information storage unit that stores information indicating the history of at least one of maintenance, ejection operation, and ejection defect inspection for each of the plurality of print heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; The additional head selection unit selects the additional head from among the remaining heads based on the information stored in the history information storage unit.

11. 11. The inkjet printing device according to claim 10, wherein, based on the information stored in the history information storage unit, the additional head selection unit selects, from the remaining heads, a print head that satisfies at least one of the following conditions: the time elapsed since the most recent cleaning operation exceeds a predetermined time; the ink ejection volume or ejection operation time exceeds an upper limit value or falls below a lower limit value; the time elapsed since the most recent ink ejection operation exceeds a predetermined time; and the frequency of ejection failure detection exceeds a predetermined value.

12. A transport mechanism for transporting a print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing-machine-specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; In an inkjet printing device, when the printing unit includes print heads of different colors and the cleaning mechanism is configured to be able to clean print heads of the same color as a unit, the additional head selection unit selects the additional head from the remaining heads based on the printing machine-specific information within a range that is not longer than the cleaning time required for the print head of the color that requires the longest cleaning time among the specified heads.

13. further comprising an operation unit that accepts input operations by a user; the operation unit accepts an input operation specifying a condition to be added for the additional head selection unit to select the additional head; 13. The inkjet printing apparatus according to claim 1, wherein the additional head selection unit selects the additional head so as to satisfy the condition specified by the input operation.

14. A transport mechanism for transporting a print medium; a printing unit including a plurality of print heads that eject ink onto the printing medium; a cleaning mechanism configured to selectively clean the plurality of print heads; a print execution control unit that prints on the print medium by causing the transport mechanism to transport the print medium and the printing unit to eject ink onto the print medium; a cleaning execution control unit that causes the cleaning mechanism to selectively perform cleaning on the plurality of print heads; a cleaning start unit that outputs a cleaning start command that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection unit that, when the cleaning start instruction is output, selects, as an additional head, a print head from among the remaining heads to be cleaned together with the designated head, based on at least one of printing machine specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; an operation unit that accepts input operations by a user; Equipped with When the cleaning start instruction is output, the print execution control unit stops printing on the print medium until the cleaning started by the cleaning start instruction is completed, the cleaning execution control unit, when the additional head is selected by the additional head selection unit in response to the cleaning start instruction, causes the cleaning mechanism to perform cleaning on the designated head and the additional head; the operation unit accepts an input operation specifying a condition to be added for the additional head selection unit to select the additional head; The additional head selection unit selects the additional head so as to satisfy the condition specified by the input operation.

15. the operation unit accepts an input operation for specifying a shortened time when selecting, as the additional head, a print head among the remaining heads that, when included in the cleaning target, will have a cleaning time that is shorter than the cleaning time required for cleaning only the designated head; The inkjet printing apparatus according to claim 14 , wherein the additional head selection unit selects the additional head so that the time shortened by including the additional head in the cleaning target compared to the time required for cleaning only the designated head is greater than the shortened time.

16. the operation unit accepts an input operation specifying the maximum number of print heads to be selected as the additional heads, The inkjet printing apparatus of claim 14 , wherein the additional head selection unit selects the additional heads such that the number of print heads selected as the additional heads does not exceed the maximum number.

17. 1. A cleaning method for an inkjet printing device that prints on a print medium by ejecting ink from a plurality of print heads onto the print medium while transporting the print medium, comprising: a cleaning start step of outputting a cleaning start instruction that designates the print head to be cleaned as a designated head when cleaning should be performed based on information indicating the ejection status of the plurality of print heads; an additional head selection step of selecting, when the cleaning start instruction is output, a print head from among the remaining heads to be cleaned together with the designated head as an additional head based on at least one of printing machine specific information indicating a configuration or function related to cleaning, information related to the print job, information indicating the dry state of the remaining heads, which are print heads other than the designated head among the plurality of print heads, the ejection operation history of the remaining heads, and the maintenance history of the remaining heads; a cleaning execution step of executing cleaning of the designated head and the additional head when the additional head is selected in response to the cleaning start instruction; In the additional head selection step, a print head that will improve at least one of printing efficiency and quality when it is targeted for cleaning together with the designated head among the remaining heads is selected as the additional head.

18. 18. The cleaning method according to claim 17, wherein in the additional head selection step, a print head among the remaining heads that, when included in the cleaning target, requires a shorter cleaning time than the cleaning time required for cleaning only the designated head is selected as the additional head based on the printing machine-specific information.

19. 18. The cleaning method according to claim 17, wherein in the additional head selection step, a print head from among the remaining heads is selected as the additional head based on the printing machine-specific information, the print head being included in the cleaning target so that the cleaning time required does not increase from the time required to clean only the designated head and printing efficiency or quality is improved.

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