Head replacement method, inkjet printing device, and head replacement support program

Abstract

To provide a head replacement method which enables detection of an abnormality of pipe connection without performing printing in an inkjet printer.SOLUTION: A head replacement method includes: a pipe connection step (S320) in which a user performs pipe connection of a new head; an ink circulation start step (S400) in which circulation of an ink in a circulation flow passage is started; and connection state determination steps (S410, S415, S500) in which whether or not pipe connection, including connection between an ink discharge pipe and a recovery branch pipe and connection between an ink inflow pipe and a supply branch pipe, is performed correctly is determined based on an ink liquid surface position indicating a height of an ink liquid surface in at least one of a recovery tank and a supply tank.SELECTED DRAWING: Figure 22

Description

Technical Field

[0001] The present invention relates to an inkjet printing apparatus, and more particularly to a method for replacing a head in an inkjet printing apparatus.

Background Art

[0002] Conventionally, an inkjet printing apparatus that prints on a printing medium (substrate) such as printing paper by ejecting ink onto the printing medium by heat or pressure has been known. The inkjet printing apparatus includes a head unit including a plurality of heads (printing heads) having a large number of nozzles for ejecting ink. The plurality of heads constituting the head unit are held by one head holding plate. One head unit is typically composed of, for example, five heads. In this case, those five heads are held by one head holding plate.

[0003] A typical inkjet printing apparatus for color printing is provided with at least a head unit for C color (cyan), a head unit for M color (magenta), a head unit for Y color (yellow), and a head unit for K color (black). Thus, typically, a head unit is provided for each color. In addition, an ink supply mechanism (ink circulation system) for supplying ink to the plurality of heads constituting the head unit is provided for each color. The ink supply mechanism is provided with a supply tank for storing ink to be supplied to the head and a recovery tank for storing ink recovered from the head, and ink flows from the supply tank through the head to the recovery tank due to the difference in air pressure (differential pressure) between the supply tank and the recovery tank. Note that in this specification, attention is paid to an inkjet printing apparatus in which a circulation flow path through which ink circulates is formed by the piping constituting the ink supply mechanism and the piping in the head. When printing is performed on the printing medium, the ink circulates through the circulation flow path.

[0004] Regarding the inkjet printing equipment described above, ink ejection problems may occur due to factors such as ink solidification (drying) caused by prolonged disuse. If printing is performed with ink ejection problems, high-quality prints cannot be obtained. Therefore, cleaning and flushing are performed as countermeasures against ink ejection problems. However, even after cleaning and flushing, ink ejection problems may not be completely resolved. In such cases, the print head experiencing the ink ejection problem is replaced. In addition, print heads may be replaced for reasons other than ink ejection problems. Typically, new print head units are provided by the printing equipment manufacturer with cleaning fluid or other liquids already filled inside.

[0005] Incidentally, head replacement is usually done manually by the user of the inkjet printer. In other words, the head replacement is not performed by a manufacturer's worker who is familiar with the structure of the inkjet printer. Therefore, when replacing the head, the connection between the piping that makes up the ink supply mechanism and the piping inside the head (hereinafter simply referred to as "piping connection") may not be made correctly. In the following, regarding piping connections, the connection between the piping that supplies ink from the supply tank to the head and the piping inside the head will be referred to as the "supply side piping connection," and the connection between the piping that recovers ink from the head to the recovery tank and the piping inside the head will be referred to as the "recovery side piping connection."

[0006] After a print head is replaced, the pressure in the supply tank is set to a high positive pressure, which should ideally cause the cleaning fluid in the replaced head (the new head) to be discharged into the head cleaning cap. However, if there is a problem with the supply side piping connection after the head is replaced, the cleaning fluid will not be discharged into the head cleaning cap, and when ink circulation in the circulation channel is restarted, the cleaning fluid will mix with the ink. As a result, printing defects will occur, and it will become necessary to remove the ink from the circulation channel. Also, if there is a problem with the recovery side piping connection after the head is replaced, when ink circulation in the circulation channel is restarted, a suitable negative pressure will not be applied to the head, and the meniscus will not form properly at each nozzle. As a result, when printing is performed, ink will unintentionally drip from each nozzle onto the printing medium, a phenomenon known as "ink dripping."

[0007] Japanese Patent Publication No. 2005-297279 discloses a technology for preventing head damage caused by abnormal (faulty) piping connections. According to this technology, an inspection means is provided on the head to check whether the update of print data in the data latch section is being performed normally. When the inspection means detects that the update of print data has been interrupted, the printing operation stops and an error signal is output. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2005-297279 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, according to the technology disclosed in Japanese Patent Publication No. 2005-297279, it is not possible to detect abnormalities in the piping connections unless printing is actually performed on the printing medium after the head is replaced. Therefore, if there is an abnormality in the piping connections, printing medium and ink will be wasted.

[0010] Therefore, the present invention relates to an inkjet printing apparatus and aims to provide a head replacement method that can detect abnormalities in pipe connections without performing printing. [Means for solving the problem]

[0011] The first invention relates to a head replacement method for an inkjet printing apparatus comprising a plurality of heads for ejecting ink toward a printing medium, a head holding plate for holding the plurality of heads, and an ink supply mechanism for supplying ink to the plurality of heads, wherein the heads to be replaced are some of the heads among the plurality of heads. The ink supply mechanism includes a supply tank for storing ink to be supplied to the plurality of heads, a recovery tank for storing ink recovered from the plurality of heads, a supply pipe forming a flow path for ink supplied from the supply tank to the plurality of heads, a recovery pipe forming a flow path for ink recovered from the plurality of heads to the recovery tank, a return pipe for returning ink from the recovery tank to the supply tank, a supply branch pipe forming a flow path for ink flowing from the supply pipe to each head, and a recovery branch pipe forming a flow path for ink flowing from each head to the recovery pipe. Each head, Ink discharge piping and A first connector for connecting the ink discharge pipe and the recovery branch pipe, Ink inlet piping and A second connector for connecting the ink inlet pipe and the supply branch pipe, Includes, A circulation path is formed through the supply tank, the supply piping, the supply branch piping, the ink inlet piping, the ink discharge piping, the recovery branch piping, the recovery piping, the recovery tank, and the return piping, through which the ink circulates. The head replacement method described above is: A piping removal step includes removing the ink inlet piping included in the head to be replaced from the supply branch piping and removing the ink discharge piping included in the head to be replaced from the recovery branch piping, A head removal step of removing the head to be replaced from the head retaining plate, A head mounting step involves attaching a new head to be used in place of the head to be replaced to the head holding plate, A piping connection step involves connecting the ink discharge piping included in the new head to the recovery branch piping via the first connector, and connecting the ink inflow piping included in the new head to the supply branch piping via the second connector, After the head mounting step and the piping connection step, an ink circulation start step is performed to start the circulation of ink in the circulation channel, After the ink circulation start step, a connection status determination step is performed to determine whether the piping connections, including the connection of the ink discharge pipe and the recovery branch pipe via the first connector and the connection of the ink inlet pipe and the supply branch pipe via the second connector, have been correctly made in the piping connection step, based on the ink level position representing the height of the ink level in at least one of the recovery tank and the supply tank. It is characterized by including.

[0012] The second invention is, in the first invention, The connection status determination step includes a first ink level position confirmation step of continuously checking a first ink level position that represents the height of the ink level in the recovery tank, The connection status determination step is characterized in that if there is a change in the first ink level position confirmed in the first ink level position confirmation step, it is determined that the piping connection is made correctly.

[0013] The third invention is, in the second invention, In the ink circulation start step, ink circulation in the circulation channel is started so that ink is supplied only to the new head among the plurality of heads. The first ink level position confirmation step is characterized in that the first ink level position is continuously confirmed while the ink is circulating in the circulation channel so that ink is supplied only to the new head among the plurality of heads.

[0014] The fourth invention is, in the second invention, The ink supply mechanism includes a first liquid level sensor for detecting the first ink liquid level position, The connection status determination step includes an ink level position reconfirmation step in which, if there is no change in the first ink level position confirmed in the first ink level position confirmation step, the ink is circulated in the circulation channel so that ink is supplied only to the non-replaceable heads, which are the heads among the plurality of heads that have not been replaced, and the first ink level position is continuously confirmed. The connection status determination step is characterized in that if there is a change in the first ink level confirmed in the ink level reconfirmation step, it is determined that there is an abnormality in the connection between the ink discharge pipe and the recovery branch pipe via the first connector, and if there is no change in the first ink level confirmed in the ink level reconfirmation step, it is determined that there is an abnormality in the first liquid level sensor.

[0015] The fifth invention is, in the second invention, The head replacement method is characterized by including a supply-side connection status determination step, which, after the head installation step and the piping connection step and before the ink circulation start step, determines whether the connection between the ink inlet pipe and the supply branch pipe via the second connector was correctly made in the piping connection step, based on a second ink level position representing the height of the ink level in the supply tank, while ensuring that only ink flows from the supply tank to the ink inlet pipe via the supply pipe and the supply branch pipe in the circulation path.

[0016] The sixth invention is, in the fifth invention, The supply side connection status determination step is: A second ink liquid surface position storage step of storing the second ink liquid surface position in a state where the supply tank is open to the atmosphere; A pressurization step of pressurizing the inside of the supply tank after the second ink liquid surface position storage step; A second ink liquid surface position confirmation step of confirming the second ink liquid surface position in a state where the supply tank is open to the atmosphere after the pressurization step; including; In the supply side connection state determination step, if the second ink liquid surface position confirmed in the second ink liquid surface position confirmation step is lower than the second ink liquid surface position stored in the second ink liquid surface position storage step, it is determined that the connection between the ink inflow pipe and the supply branch pipe via the second connector is correctly made.

[0017] A seventh invention is the sixth invention, The ink supply mechanism includes a second liquid surface sensor for detecting the second ink liquid surface position, The connection state determination step includes an ink liquid surface position reconfirmation step of continuously confirming the second ink liquid surface position in a state where ink is circulated in the circulation flow path so that ink is supplied only to a non-replacement target head, which is a head that has not been replaced among the plurality of heads, if the second ink liquid surface position confirmed in the second ink liquid surface position confirmation step is not lower than the second ink liquid surface position stored in the second ink liquid surface position storage step. In the connection state determination step, if there is a change in the second ink liquid surface position confirmed in the ink liquid surface position reconfirmation step, it is determined that there is an abnormality in the connection between the ink inflow pipe and the supply branch pipe via the second connector, and if there is no change in the second ink liquid surface position confirmed in the ink liquid surface position reconfirmation step, it is determined that there is an abnormality in the second liquid surface sensor.

[0018] An eighth invention is the first invention, The head replacement method includes, prior to the piping removal step and the head removal step, an ink level position pre-confirmation step in which the ink level is continuously checked while the ink is circulated in the circulation channel so that ink is supplied only to the head to be replaced among the plurality of heads, The piping removal step, the head removal step, the head installation step, the piping connection step, the ink circulation start step, and the connection status determination step are executed only if there is a change in the ink level position confirmed in the ink level position pre-check step.

[0019] The ninth invention is, in the eighth invention, The ink supply mechanism includes a liquid level sensor for detecting the ink level, a supply control valve for controlling the flow of ink in the supply branch pipe, and a recovery control valve for controlling the flow of ink in the recovery branch pipe. The head replacement method includes a liquid level sensor inspection step in which, if there is no change in the ink liquid level position confirmed in the ink liquid level pre-confirmation step, ink is supplied only to the non-replacement target heads, which are among the multiple heads that were not replaced, while the ink is circulated in the circulation channel and the ink liquid level position is continuously checked. If there is a change in the ink level position confirmed in the liquid level sensor inspection step, it is determined that there is an abnormality in the supply control valve or the recovery control valve corresponding to the head to be replaced. If there is no change in the ink level position confirmed in the liquid level sensor inspection step, it is determined that there is an abnormality in the liquid level sensor.

[0020] The tenth invention is, in the ninth invention, The ink supply mechanism includes, as the liquid level sensor, a first liquid level sensor that detects a first ink liquid level position representing the height of the ink liquid level in the recovery tank, and a second liquid level sensor that detects a second ink liquid level position representing the height of the ink liquid level in the supply tank. In the ink level position pre-confirmation step and the liquid level sensor inspection step, the first ink level position and the second ink level position are confirmed as the ink level position. If there is no change in the first ink level position confirmed in the ink level position pre-check step, and there is a change in the first ink level position confirmed in the ink level sensor inspection step, then it is determined that there is an abnormality in the recovery control valve corresponding to the head to be replaced. If there is no change in the first ink level position confirmed in the ink level position pre-check step, and there is no change in the first ink level position confirmed in the liquid level sensor inspection step, then it is determined that there is an abnormality in the first liquid level sensor. If there is no change in the second ink level position confirmed in the ink level position pre-check step, and there is a change in the second ink level position confirmed in the ink level sensor inspection step, then it is determined that there is an abnormality in the supply control valve corresponding to the head to be replaced. The method is characterized in that if there is no change in the second ink level position confirmed in the ink level position pre-check step, and there is no change in the second ink level position confirmed in the liquid level sensor inspection step, it is determined that there is an abnormality in the second liquid level sensor.

[0021] The eleventh invention is, in the first invention, The ink supply mechanism includes a first liquid level sensor that detects a first ink level position representing the height of the ink liquid in the recovery tank, and a second liquid level sensor that detects a second ink level position representing the height of the ink liquid in the supply tank. The connection status determination step is characterized in that it is determined whether the piping connection is made correctly based on at least one of the first ink level position detected by the first liquid level sensor and the second ink level position detected by the second liquid level sensor.

[0022] The twelfth invention relates to any of the first to eleventh inventions, The inkjet printing apparatus includes a control device that controls the operation of the plurality of heads and the ink supply mechanism, The aforementioned pipe removal step, head removal step, head installation step, and pipe connection step are performed by an operator. The ink circulation start step and the connection status determination step are characterized by being performed by the control device.

[0023] The 13th invention is, in the 12th invention, The control device has a display unit, The connection status determination step is characterized in that the determination result of whether the piping connection has been made correctly is displayed on the display unit.

[0024] The fourteenth invention is an inkjet printing apparatus comprising a plurality of heads for ejecting ink toward a printing medium, an ink supply mechanism for supplying ink to the plurality of heads, and a control device for controlling the operation of the plurality of heads and the ink supply mechanism, The ink supply mechanism includes a supply tank for storing ink to be supplied to the plurality of heads, a recovery tank for storing ink recovered from the plurality of heads, a supply pipe forming a flow path for ink supplied from the supply tank to the plurality of heads, a recovery pipe forming a flow path for ink recovered from the plurality of heads to the recovery tank, a return pipe for returning ink from the recovery tank to the supply tank, a supply branch pipe forming a flow path for ink flowing from the supply pipe to each head, and a recovery branch pipe forming a flow path for ink flowing from each head to the recovery pipe. Each head, Ink discharge piping and A first connector for connecting the ink discharge pipe and the recovery branch pipe, Ink inlet piping and A second connector for connecting the ink inlet pipe and the supply branch pipe, Includes, A circulation path is formed through the supply tank, the supply piping, the supply branch piping, the ink inlet piping, the ink discharge piping, the recovery branch piping, the recovery piping, the recovery tank, and the return piping, through which the ink circulates. The control device is A message output step that outputs a message prompting the replacement of the head, A replacement completion confirmation step that receives input indicating that the head replacement has been completed, An ink circulation start step is performed to initiate the circulation of ink in the circulation channel so that ink is supplied to the new head, which is the head after replacement. A connection status determination step, based on the ink level position representing the height of the ink level in at least one of the recovery tank and the supply tank, determines whether the piping connections, including the connection between the ink discharge pipe and the recovery branch pipe included in the new head via the first connector and the connection between the ink inlet pipe and the supply branch pipe included in the new head via the second connector, are properly made. This method is characterized by executing the following steps in this order.

[0025] The 15th invention is a head replacement support program, In an inkjet printing apparatus comprising a plurality of heads for ejecting ink toward a printing medium, an ink supply mechanism for supplying ink to the plurality of heads, and a control device for controlling the operation of the plurality of heads and the ink supply mechanism, a computer included in the control device, A message output step that outputs a message prompting the replacement of the head, A replacement completion confirmation step that receives input indicating that the head replacement has been completed, A replacement work result inspection step to check whether the head replacement was performed correctly, and Make it run, The ink supply mechanism includes a supply tank for storing ink to be supplied to the plurality of heads, a recovery tank for storing ink recovered from the plurality of heads, a supply pipe forming a flow path for ink supplied from the supply tank to the plurality of heads, a recovery pipe forming a flow path for ink recovered from the plurality of heads to the recovery tank, a return pipe for returning ink from the recovery tank to the supply tank, a supply branch pipe forming a flow path for ink flowing from the supply pipe to each head, and a recovery branch pipe forming a flow path for ink flowing from each head to the recovery pipe. Each head, Ink discharge piping and A first connector for connecting the ink discharge pipe and the recovery branch pipe, Ink inlet piping and A second connector for connecting the ink inlet pipe and the supply branch pipe, Includes, A circulation path is formed through the supply tank, the supply piping, the supply branch piping, the ink inlet piping, the ink discharge piping, the recovery branch piping, the recovery piping, the recovery tank, and the return piping, through which the ink circulates. The aforementioned replacement work result inspection step is: An ink circulation start step is performed to initiate the circulation of ink in the circulation channel so that ink is supplied to the new head, which is the head after replacement. A connection status determination step, based on the ink level position representing the height of the ink level in at least one of the recovery tank and the supply tank, determines whether the piping connections, including the connection between the ink discharge pipe and the recovery branch pipe included in the new head via the first connector and the connection between the ink inlet pipe and the supply branch pipe included in the new head via the second connector, are properly made. It is characterized by including. [Effects of the Invention]

[0026] According to the first invention described above, after the user has finished replacing the print head, a determination is made as to whether the piping connections, including the connection between the ink discharge pipe and the recovery branch pipe, and the connection between the ink inlet pipe and the supply branch pipe, are properly made, based on the ink level position in at least one of the recovery tank and the supply tank. Even if ink circulation in the circulation channel begins, if there is a problem with the piping connections, the ink level position will not change, so the problem with the piping connections can be detected without printing on the printing medium. As described above, it is possible to provide a print head replacement method for an inkjet printing apparatus that can detect a problem with the piping connections without printing.

[0027] According to the second invention described above, the same effects as the first invention described above can be obtained.

[0028] According to the third invention described above, the first ink level position can be confirmed in a state where ink is not circulating to the non-replaceable head, making it possible to accurately detect the state of the piping connection of the new head.

[0029] According to the fourth invention described above, when an abnormality is detected, it becomes possible to distinguish between an abnormality in the connection between the ink discharge pipe and the recovery branch pipe and an abnormality in the first liquid level sensor.

[0030] According to the fifth invention described above, it is possible to detect whether the connection between the ink inlet pipe and the supply branch pipe is made correctly without performing any printing.

[0031] According to the sixth invention described above, the same effects as those of the fifth invention described above can be obtained.

[0032] According to the seventh invention described above, when an abnormality is detected, it becomes possible to distinguish between an abnormality in the connection between the ink inlet pipe and the supply branch pipe and an abnormality in the second liquid level sensor.

[0033] According to the eighth invention described above, it becomes possible to detect abnormalities in existing components (such as liquid level sensors and valves) before the head is actually replaced.

[0034] According to the ninth invention described above, it becomes possible to distinguish between a valve malfunction and a liquid level sensor malfunction when an abnormality is detected.

[0035] According to the tenth invention described above, when an abnormality is detected, it becomes possible to distinguish between an abnormality in the recovery control valve, an abnormality in the supply control valve, an abnormality in the first liquid level sensor, and an abnormality in the second liquid level sensor.

[0036] According to the 11th invention described above, the same effects as those of the first invention described above can be obtained.

[0037] According to the 12th invention described above, it becomes possible to detect abnormalities in the piping connections associated with head replacement without imposing any special operational burden on the user.

[0038] According to the 13th invention described above, the user can quickly determine whether the piping connections have been made correctly after replacing the print head, without having to print anything.

[0039] According to the 14th invention described above, the same effects as those of the first invention described above can be obtained.

[0040] According to the 15th invention described above, the same effects as those of the first invention described above can be obtained. [Brief explanation of the drawing]

[0041] [Figure 1] This is a schematic diagram showing one example configuration of an inkjet printing apparatus according to one embodiment of the present invention. [Figure 2] This is a plan view showing one example of the configuration of the printing section in the above embodiment. [Figure 3] The above embodiment is a schematic diagram showing the configuration of an ink supply mechanism corresponding to one head unit. [Figure 4] This is a schematic perspective view showing the appearance of the head (print head) in the above embodiment. [Figure 5] This figure illustrates the head retaining plate that holds the head in the above embodiment. [Figure 6] This diagram schematically shows the positional relationship between the head and the cleaning mechanism when the head is being cleaned in the above embodiment. [Figure 7] This diagram schematically shows the positional relationship between the print head and the cleaning mechanism when printing is performed on the printing paper in the above embodiment. [Figure 8] This is a block diagram showing the hardware configuration of the print control device in the above embodiment. [Figure 9] This is a block diagram illustrating the configuration related to the control of the ink supply mechanism in the above embodiment. [Figure 10] This diagram shows the state of the ink supply mechanism when ink is circulating normally in the circulation channel before the print head is replaced. [Figure 11] This diagram shows the state of the ink supply mechanism when ink circulation in the circulation channel has stopped. [Figure 12] This diagram shows the state of the ink supply mechanism when the old print head has been removed from the print head retaining plate. [Figure 13] This diagram shows the state of the ink supply mechanism when cleaning is performed. [Figure 14] This diagram shows the state of the ink supply mechanism when the supply tank is vented to the atmosphere after cleaning is performed. [Figure 15] This diagram shows the state of the ink supply mechanism when ink circulation in the circulation channel is resumed after the print head is replaced. [Figure 16] This flowchart shows the procedure for head replacement in the above embodiment. [Figure 17] This flowchart shows the procedure for head replacement in the above embodiment. [Figure 18] The diagram illustrates how, in the above embodiment, only the valve corresponding to the head to be replaced is set to the open state. [Figure 19] This figure shows an example of a head replacement screen in the above embodiment. [Figure 20]In the above embodiment, the flowchart shows the procedure for the user to replace the head. [Figure 21] This figure shows an example of a pipe connection promotion screen in the above embodiment. [Figure 22] This flowchart shows the procedure for head replacement in the first modified example of the above embodiment. [Figure 23] This flowchart shows the procedure for head replacement in a second modified example of the above embodiment. [Modes for carrying out the invention]

[0042] An embodiment of the present invention will be described below with reference to the attached drawings.

[0043] <1. Schematic Configuration of an Inkjet Printing System> Figure 1 is a schematic diagram showing one configuration example of an inkjet printing apparatus 10 according to one embodiment of the present invention. This inkjet printing apparatus 10 is composed of a printing control device 100 and a printing press body 200. The printing press body 200 includes a paper delivery unit 21 that supplies printing paper (e.g., roll paper) PA, which is the printing medium, a printing mechanism 20 that performs printing on the printing paper PA, and a paper winding unit 29 that winds up the printing paper PA after printing. The printing mechanism 20 includes a first drive roller 22 for transporting the printing paper PA into the interior, a plurality of support rollers 23 for transporting the printing paper PA inside the printing mechanism 20, a printing unit 24 that prints on the printing paper PA by ejecting ink, a cleaning mechanism 25 that cleans the printing unit 24, a drying unit 26 for drying the printing paper PA after printing, an imaging unit 27 that captures a printed image (printed printing paper PA) and checks the quality of the printed image and the ink ejection state from the nozzles, which will be described later, and a second drive roller 28 for outputting the printing paper PA from inside the printing mechanism 20. Furthermore, the imaging data Dc obtained by capturing the print image by the imaging unit 27 is sent to the print control device 100, where an inspection is performed using the imaging data Dc.

[0044] The print control device 100 controls the operation of the printing press body 200 configured as described above. When the print control device 100 receives a print output command, it controls the operation of the printing press body 200 so that the printing paper PA is transported from the paper feeding unit 21 to the paper winding unit 29. First, the printing unit 24 prints on the printing paper PA, then the drying unit 26 dries the printing paper PA, and finally, if necessary, the imaging unit 27 captures the printed image. Also, if necessary, the cleaning mechanism 25 cleans the printing unit 24.

[0045] Figure 2 is a plan view showing one example configuration of the printing unit 24. As shown in Figure 2, the printing unit 24 is composed of head units 2C, 2M, 2Y, and 2K for C (cyan), M (magenta), Y (yellow), and K (black), arranged in a row in the transport direction of the printing paper PA. Each head unit is composed of multiple (five in this embodiment) heads (print heads) 240 arranged in a staggered pattern. Each head 240 contains numerous nozzles that eject ink. Each nozzle of the head 240 in the C-color head unit 2C ejects C-color ink, each nozzle of the head 240 in the M-color head unit 2M ejects M-color ink, each nozzle of the head 240 in the Y-color head unit 2Y ejects Y-color ink, and each nozzle of the head 240 in the K-color head unit 2K ejects K-color ink.

[0046] <2. Ink supply mechanism> Figure 3 is a schematic diagram showing the configuration of an ink supply mechanism corresponding to one head unit. The ink supply mechanism includes a supply tank 52 for storing ink to supply to five heads 240(1) to 240(5), a recovery tank 51 for storing ink recovered from the five heads 240(1) to 240(5), a first pressure adjustment mechanism 512 for adjusting the air pressure in the recovery tank 51, a second pressure adjustment mechanism 522 for adjusting the air pressure in the supply tank 52, a first liquid level sensor 511 for detecting a first ink level position representing the height of the ink liquid in the recovery tank 51, a second liquid level sensor 521 for detecting a second ink level position representing the height of the ink liquid in the supply tank 52, a supply pipe (supply manifold) 53 that forms a flow path for ink supplied from the supply tank 52 to the five heads 240(1) to 240(5), and a flow path for ink recovered from the five heads 240(1) to 240(5) to the recovery tank 51. A recovery pipe (recovery manifold) 54, a return pipe 55 for returning ink from the recovery tank 51 to the supply tank 52, five supply branch pipes 530(1) to 530(5) that form ink flow paths from the supply pipe 53 to each of the five heads 240(1) to 240(5), and five recovery branch pipes that form ink flow paths from each of the five heads 240(1) to 240(5) to the recovery pipe 54. The system includes five supply control valves 531(1) to 531(5) corresponding to the five heads 240(1) to 240(5), five recovery control valves 541(1) to 541(5) corresponding to the five heads 240(1) to 240(5), a pump 551 provided in the recirculation pipe 55, and a return control valve 552 provided in the recirculation pipe 55. Each supply control valve 531 controls the flow of ink in the corresponding supply branch pipe 530, each recovery control valve 541 controls the flow of ink in the corresponding recovery branch pipe 540, and the return control valve 552 controls the flow of ink in the recirculation pipe 55. The pump 551 delivers ink from the recovery tank 51 to the supply tank 52. The supply control valve 531, the recovery control valve 541, and the return control valve 552 are typically solenoid valves that control the flow of ink by switching them on and off.

[0047] In the above configuration, a circulation channel is formed in which ink circulates in the following order: "supply tank 52 ~ supply pipe 53 ~ supply branch pipe 531 ~ head 240 ~ recovery branch pipe 541 ~ recovery pipe 54 ~ recovery tank 51 ~ return pipe 55 ~ supply tank 52".

[0048] <3. Head Configuration> Figure 4 is a schematic perspective view showing the external appearance of the print head 240. As shown in Figure 4, the print head 240 includes a main body 241, a base plate 242, a communication connector 243 for connecting to a communication cable for drive signals, an ink discharge pipe 244, a first non-spill 245 which functions as a connector for connecting the ink discharge pipe 244 to a recovery branch pipe 540, an ink inlet pipe 246, and a second non-spill 247 which functions as a connector for connecting the ink inlet pipe 246 to a supply branch pipe 530. The ink discharge pipe 244 and the ink inlet pipe 246 are components that form the circulation path described above. The first connector is realized by the first non-spill 245, and the second connector is realized by the second non-spill 247.

[0049] The main body 241 includes an internal tank (not shown). The base plate 242 includes ink channels for ink flowing from the ink inlet pipe 246 to the internal tank and ink channels for ink flowing from the internal tank to the ink discharge pipe 244. The main body 241 is also provided with numerous nozzles exposed on the back side of the base plate 242. A cavity for storing ink is provided between each nozzle and the internal tank, and a piezoelectric element is provided in the cavity. In this configuration, when a drive signal having a predetermined drive waveform is applied to the piezoelectric element, the piezoelectric element deforms based on the drive signal. As a result, ink is pushed out of the cavity and ejected from the nozzle.

[0050] Figure 5 is a diagram illustrating the head holding plate 40 that holds the head 240. The head holding plate 40 is a plate-shaped member, and in this embodiment, it is provided with five head holding sections 41 for holding five heads 240. When attaching the head 240 to the head holding plate 40, the base plate 242 of the head 240 is positioned at the head holding section 41, as indicated by the arrows labeled 49. Each head holding section 41 has a through hole 42. Because the head holding section 41 has a through hole 42, when the head 240 is held by the head holding section 41, the numerous nozzles provided on the head 240 are exposed on the back side of the head holding plate 40. This makes it possible to eject ink from the head 240 onto the printing paper PA.

[0051] <4. Cleaning Mechanism> The configuration and operation of the cleaning mechanism 25 will be described with reference to Figures 6 and 7. Figure 6 is a schematic diagram showing the positional relationship between the head 240 and the cleaning mechanism 25 when the head 240 is being cleaned, and Figure 7 is a schematic diagram showing the positional relationship between the head 240 and the cleaning mechanism 25 when printing is being performed on the printing paper PA. In this embodiment, the position of the cleaning mechanism 25 can be moved by control by the print control device 100. Hereinafter, for convenience, the position of the cleaning mechanism 25 when cleaning is being performed (see Figure 6) will be referred to as the "home position," and the position of the cleaning mechanism 25 when printing is being performed on the printing paper PA (see Figure 7) will be referred to as the "away position."

[0052] The cleaning mechanism 25 consists of a cap unit 251 containing multiple caps 252 and a wiper unit 253 containing a wiper 254. When cleaning is performed, as shown in Figure 6, each cap 252 covers the corresponding printing surface of the head 240, sealing the printing surface. In this state, a purging process (pressurized purging) is performed by increasing the air pressure in the internal tank inside the head 240 to forcibly eject any ink remaining in the nozzles toward the caps 252. When cleaning is completed, the cleaning mechanism 25 moves from the home position to the away position. As the cleaning mechanism 25 moves from the home position to the away position, a wiping process is performed by the wiper 254 to wipe away any dirt from the printing surface of the head 240.

[0053] <5. Configuration for Control> <5.1 Hardware configuration of the print control device> Figure 8 is a block diagram showing the hardware configuration of the print control device 100. As shown in Figure 8, the print control device 100 includes a main unit 110, an auxiliary storage device 121, an optical disc drive 122, a display unit 123, a keyboard 124, and a mouse 125. The main unit 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, and a communication interface unit 117. The CPU 111, memory 112, first disk interface unit 113, second disk interface unit 114, display control unit 115, input interface unit 116, and communication interface unit 117 are connected to each other via a system bus. The auxiliary storage device 121 is connected to the first disk interface unit 113. The optical disc drive 122 is connected to the second disk interface unit 114. The display unit (display device) 123 is connected to the display control unit 115. The input interface unit 116 is connected to a keyboard 124 and a mouse 125. The communication interface unit 117 is connected to the printer body 200 via a communication cable. The communication interface unit 117 is also connected to LAN 4. The auxiliary storage device 121 is a magnetic disk drive or the like. An optical disk 5, 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 operator. The keyboard 124 and mouse 125 are used by the operator to input instructions to this print control device 100.

[0054] The auxiliary storage device 121 stores a print control program (a program for controlling the execution of printing processes by the printing press 200) 18. The print control program 18 includes a head replacement support program 19 as a subprogram to assist the user in replacing the head 240. The CPU 111 realizes various functions of the print control device 100 by reading the print control program 18 stored in the auxiliary storage device 121 into the memory 112 and executing it. 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 18 stored in the auxiliary storage device 121. The print control program 18 is provided stored on the above-mentioned computer-readable recording medium (non-transient recording medium). That is, for example, the user purchases an optical disc 5 as the recording medium for the print control program 18, inserts it into the optical disc drive 122, reads the print control program 18 from the optical disc 5, and installs it into the auxiliary storage device 121.

[0055] <5.2 Configuration related to the control of the ink supply mechanism> Figure 9 is a block diagram illustrating the configuration related to the control of the ink supply mechanism described above. As can be seen from Figure 9, the operation of the head 240, cleaning mechanism 25, first liquid level sensor 511, first pressure adjustment mechanism 512, second liquid level sensor 521, second pressure adjustment mechanism 522, supply control valve 531, recovery control valve 541, pump 551, and return control valve 552 is controlled by a control unit 150, which is realized by executing a print control program 18 in the print control device 100.

[0056] <6. How to replace the head> <6.1 Basic procedure for head replacement> Before describing the head replacement procedure in this embodiment, we will explain the basic flow of head replacement. Here, we will focus on the state of each component in a case where head replacement is performed normally without any abnormalities using the conventional procedure. Note that in Figures 10 to 15, illustrations of heads other than the head to be replaced and their corresponding components have been omitted. Furthermore, in the following, circulating ink through a circulation channel so that ink is supplied only to a specific head among multiple heads 240 will be referred to as "single-head circulation".

[0057] The state of the ink supply mechanism when ink circulation in the circulation channel is proceeding normally before head replacement is as shown in Figure 10. At this time, the supply control valve 531 corresponding to the head to be replaced, the recovery control valve 541 corresponding to the head to be replaced, and the return control valve 552 are open, and the pump 551 is operating. The supply control valve 531 corresponding to heads other than the head to be replaced and the recovery control valve 541 corresponding to heads other than the head to be replaced are also open. In addition, the air pressure in the recovery tank 51 is set to negative pressure by the first pressure adjustment mechanism 512, and the air pressure in the supply tank 52 is set to positive pressure by the second pressure adjustment mechanism 522. Since ink is circulating in the circulation channel, the first ink level position (the height of the ink level in the recovery tank 51 detected by the first liquid level sensor 511) and the second ink level position (the height of the ink level in the supply tank 52 detected by the second liquid level sensor 521) are constantly changing.

[0058] Prior to actually replacing the old print head with a new one, the circulation of ink in the circulation channel is stopped. The state of the ink supply mechanism when the circulation of ink in the circulation channel is stopped is as shown in Figure 11. At this time, all supply control valves 531, all recovery control valves 541, and return control valve 552 are closed, and the pump 551 is stopped. Since the circulation of ink in the circulation channel is stopped, there is no inflow of ink into the recovery tank 51 and no outflow of ink from the recovery tank 51, nor is there any inflow of ink into the supply tank 52 and no outflow of ink from the supply tank 52. Therefore, the first ink level position and the second ink level position do not change.

[0059] With the ink circulation in the circulation channel stopped, the old head is replaced with a new one. First, the wiring for the drive signal (communication cable) is removed from the communication connector 243 (see Figure 4) of the old head. Next, the recovery branch pipe 540 and the supply branch pipe 530 are removed from the first non-spill 245 and the second non-spill 247 of the old head, respectively. Then, the old head is removed from the head holding plate 40. The state of the ink supply mechanism at this time is as shown in Figure 12. After that, the new head is attached to the head holding plate 40, the recovery branch pipe 540 and the supply branch pipe 530 are connected to the first non-spill 245 and the second non-spill 247 of the new head, respectively, and the wiring for the drive signal (communication cable) is connected to the communication connector 243 of the new head.

[0060] Subsequently, the supply control valve 531 corresponding to the new head is set to the open position, and the pressure inside the supply tank 52 is greatly increased by the second pressure adjustment mechanism 522 (a large amount of pressure is applied inside the supply tank 52). As a result, the ink in the supply tank 52 flows to the new head 240 via the supply pipe 53 and the supply branch pipe 530, and the cleaning fluid inside the new head 240 is discharged to the head cleaning cap 252. In this way, cleaning (pressurized purging) is performed. The state of the ink supply mechanism at this time is as shown in Figure 13. At this time, the first ink level does not change, but the second ink level decreases.

[0061] Next, the supply control valve 531 corresponding to the new head is set to the closed position, and the supply tank 52 is released to the atmosphere by the second pressure adjustment mechanism 522. The state of the ink supply mechanism at this time is as shown in Figure 14. The second ink level rises due to the release to the atmosphere, but it remains lower than the position before cleaning. The first ink level does not change.

[0062] After the supply tank 52 is released to the atmosphere, all supply control valves 531, including the supply control valve 531 corresponding to the new head, all recovery control valves 541, including the recovery control valve 541 corresponding to the new head, and the return control valve 552 are set to the open state, and the pump 551 is set to the operating state. In addition, the air pressure in the recovery tank 51 is set to negative pressure by the first pressure adjustment mechanism 512, and the air pressure in the supply tank 52 is set to positive pressure by the second pressure adjustment mechanism 522. In this way, ink circulation in the circulation channel is restarted. The state of the ink supply mechanism at this time is as shown in Figure 15. As ink circulates in the circulation channel, the first ink level and the second ink level change from time to time.

[0063] <6.2 Head Replacement Procedure> Based on the above, the head replacement process in this embodiment (a series of processes related to head replacement, including the actual replacement of the old head with a new head) will now be described. Figures 16 and 17 are flowcharts showing the procedure for the head replacement process in this embodiment.

[0064] The control unit 150 sequentially performs the following actions based on the image acquisition results of the print image by the imaging unit 27: determining whether a head replacement is necessary and, if a head replacement is necessary, identifying the head to be replaced. If a head replacement is necessary, the control unit 150 starts the head replacement process. First, ink is circulated to the head to be replaced (step S100). Specifically, ink circulation is performed by setting only the valves corresponding to the head to be replaced from among the supply control valves 531(1) to 531(5) and recovery control valves 541(1) to 541(5) to the open state. For example, if head 240(3) is the head to be replaced, as shown in Figure 18, only the supply control valve 531(3) and the recovery control valve 541(3) from among the supply control valves 531(1) to 531(5) and recovery control valves 541(1) to 541(5) are set to the open state. In addition, the air pressure in the recovery tank 51 is set to negative pressure, and the air pressure in the supply tank 52 is set to positive pressure. The return control valve 552 is open, and the pump 551 is operating. In this manner, ink is circulated through the circulation channel so that ink is supplied only to the head to be replaced among the multiple heads 240 that make up the head unit 2.

[0065] Next, while the ink is being circulated to the head to be replaced, the first and second ink levels are continuously monitored, and it is determined whether or not there is a change in both the first and second ink levels (step S110). If there is a change in both the first and second ink levels, the process proceeds to step S300; if there is no change in at least one of the first and second ink levels, the process proceeds to step S200.

[0066] In step S200, ink is circulated to the non-replaceable print heads. Specifically, ink circulation is performed by setting only the valves corresponding to the replaceable print heads among the supply control valves 531(1) to 531(5) and recovery control valves 541(1) to 541(5) to the closed state.

[0067] Next, with ink circulating to the non-replaceable head, the first and second ink levels are checked, and it is determined whether there is a change in either the first or second ink level (step S210). If there is a change in either the first or second ink level, it is determined that there is a problem with the valve corresponding to the head to be replaced (step S220). If there is no change in at least one of the first or second ink level, it is determined that there is a problem with the ink level sensor (step S230). If a problem is detected in step S220 or step S230, the faulty equipment is repaired or replaced by a service technician, and then the process is restarted from step S100. In detail, the determination in step S220 is made as follows. If there is no change in the first ink level in step S110, it is determined that there is a problem with the recovery control valve 541 corresponding to the head to be replaced. If there is no change in the second ink level in step S110, it is determined that there is a problem with the supply control valve 531 corresponding to the head to be replaced. Furthermore, in step S230, the determination is made in more detail as follows: If there is no change in the first ink level in step S110, it is determined that there is a problem with the first liquid level sensor 511. If there is no change in the second ink level in step S110, it is determined that there is a problem with the second liquid level sensor 521.

[0068] In step S300, the circulation of ink in the circulation channel is stopped. Specifically, the supply control valves 531(1) to 531(5), the recovery control valves 541(1) to 541(5), and the return control valve 552 are set to the closed state, and the pump 551 is set to the stopped state, thereby stopping the circulation of ink in the circulation channel.

[0069] Subsequently, a head replacement screen 600, such as the one shown in Figure 19, containing a message prompting the user to replace the print head, is displayed on the display unit 123 of the print control device 100 (step S310). In Figure 19, "N" is a temporary number used to identify the old print head to be replaced. The head replacement screen 600 includes a completion button 610 for the user to press after completing the print head replacement process.

[0070] After the head replacement screen is displayed, the user performs the head replacement procedure (step S320). That is, the user actually removes the old head from head unit 2 and installs the new head into head unit 2.

[0071] Figure 20 is a flowchart showing the procedure for a user to replace a print head. First, the user disconnects the wiring for the drive signal from the communication connector 243 (see Figure 4) of the print head to be replaced (step S11). Next, the user disconnects the ink supply piping (step S12). Specifically, the user disconnects the recovery branch piping 540 and the supply branch piping 530 from the first non-spill 245 and the second non-spill 247 of the print head to be replaced, respectively. That is, the ink discharge piping 244 included in the print head to be replaced is disconnected from the recovery branch piping 540, and the ink inlet piping 246 included in the print head to be replaced is disconnected from the supply branch piping 530. Next, the user disconnects the old print head, which is the print head to be replaced, from the print head retaining plate 40 (step S13). After that, the user installs the new print head onto the print head retaining plate 40 (step S14). Next, the user connects the ink supply piping (step S15). More specifically, the user connects the recovery branch pipe 540 and the supply branch pipe 530 to the first non-spill 245 and second non-spill 247 of the new head, respectively. That is, the ink discharge pipe 244 included in the new head is connected to the recovery branch pipe 540, and the ink inlet pipe 246 included in the new head is connected to the supply branch pipe 530. Finally, the user connects the wiring for the drive signal to the communication connector 243 of the new head (step S16).

[0072] In this embodiment, step S12 is the pipe removal step, step S13 is the head removal step, step S14 is the head installation step, and step S15 is the pipe connection step.

[0073] After the user has replaced the print head as described above, the user presses the completion button 610, which is included in the head replacement screen 600 (see Figure 19) displayed on the display unit 123 of the print control device 100 (step S330). In this way, the print control device 100 receives input indicating that the head replacement (replacement) is complete.

[0074] After the completion button 610 is pressed, the supply tank 52 is released to the atmosphere by the second pressure adjustment mechanism 522. The ink level position in the supply tank 52 in the state of being released to the atmosphere (second ink level position) is detected by the second liquid level sensor 521, and the detected ink level position is stored (step S340). At this time, the supply control valves 531(1) to 531(5), the recovery control valves 541(1) to 541(5), and the return control valve 552 are set to the closed state.

[0075] Next, the new head is cleaned (step S350). In step S350, the cleaning mechanism 25 first moves from the away position to the home position. Then, after only the supply control valve 531 corresponding to the new head is set to the open position, the pressure inside the supply tank 52 is greatly increased by the second pressure adjustment mechanism 522 (a large amount of pressure is applied inside the supply tank 52). As a result, ink flows from the supply tank 52 to the new head, and the cleaning fluid inside the new head is discharged to the cap 252 that covers the new head. Alternatively, the new head may be cleaned by setting only the recovery control valve 531 corresponding to the new head to the open position and greatly increasing the pressure inside the recovery tank 51 by the first pressure adjustment mechanism 512. Furthermore, in this embodiment, the cleaning fluid inside the new head is discharged to the cap 252 by pressurized purging, but the present invention is not limited to this, and the cleaning fluid inside the new head may also be discharged to the cap 252 by suction purging using a suction pump connected to the cap 252.

[0076] Next, after the supply control valve 531 corresponding to the new head is set to the closed position, the supply tank 52 is opened to the atmosphere by the second pressure adjustment mechanism 522. Then, the ink level position in the supply tank 52 in the open-to-the-air state (second ink level position) is detected by the second liquid level sensor 521 (step S360).

[0077] Next, it is determined whether the ink level detected in step S360 has changed from the ink level stored in step S340 (step S370). More specifically, it is determined whether the ink level detected in step S360 is lower than the ink level stored in step S340. If the ink level detected in step S360 is lower than the ink level stored in step S340, the process proceeds to step S400. If the ink level detected in step S360 is not lower than the ink level stored in step S340, the process proceeds to step S600. If no abnormality occurs, the ink level detected in step S360 will be lower than the ink level stored in step S340.

[0078] In step S400, a single ink circulation to the new print head is performed (step S400). Specifically, the ink circulation is performed by setting only the valve corresponding to the new print head among the supply control valves 531(1) to 531(5) and recovery control valves 541(1) to 541(5) to the open state. At this time, the air pressure in the recovery tank 51 is set to negative pressure, the air pressure in the supply tank 52 is set to positive pressure, the return control valve 552 is set to the open state, and the pump 551 is set to the operating state.

[0079] Subsequently, while the ink is being circulated to the new head, the first ink level is continuously monitored, and it is determined whether or not there is a change in the first ink level (step S410). If there is a change in the first ink level, it is determined that the head replacement was performed successfully (step S500), and this head replacement process ends. On the other hand, if there is no change in the first ink level, the process proceeds to step S600.

[0080] In step S600, ink is circulated to the non-replacement head, similar to step S200. Next, while ink is circulating to the non-replacement head, the first and second ink levels are checked, and it is determined whether there is a change in either the first or second ink level (step S610). If there is a change in either the first or second ink level, the process proceeds to step S700. On the other hand, if there is no change in at least one of the first or second ink level, it is determined that there is an abnormality in the ink level sensor (step S800), and the head replacement process is terminated. At this point, after the malfunctioning ink level sensor is repaired or replaced by a service technician, the process is restarted, for example, from step S340. In step S800, the determination is made in more detail as follows. If there is no change in the first ink level position in step S410, it is determined that there is an abnormality in the first liquid level sensor 511. If there is no change in the second ink level position in step S370, it is determined that there is an abnormality in the second liquid level sensor 521.

[0081] In step S700, a determination is made as to whether there is an abnormality in the piping connection. Specifically, if there is no change in the first ink level in step S410, a determination is made as to whether there is an abnormality in the connection between the ink discharge pipe 244 and the recovery branch pipe 540 via the first non-spill pipe 245 for the new head, and if there is no change in the second ink level in step S370, a determination is made as to whether there is an abnormality in the connection between the ink inlet pipe 246 and the supply branch pipe 530 via the second non-spill pipe 247 for the new head.

[0082] Subsequently, a piping connection prompt screen 700, such as the one shown in Figure 21, containing a message prompting the user to redo the piping connection, is displayed on the display unit 123 of the print control device 100 (step S710). The piping connection prompt screen 700 includes a complete button 710 for the user to press after completing the piping connection work. Figure 21 shows an example of a message displayed when there is an abnormality in the connection between the ink inlet pipe 246 and the supply branch pipe 530 via the second non-spill pipe 247 for a new head.

[0083] After the display of the piping connection prompt screen 700, the user is asked to redo the piping connections (for the new head, the connection between the ink discharge pipe 244 and the recovery branch pipe 540 via the first non-spill pipe 245, and the connection between the ink inlet pipe 246 and the supply branch pipe 530 via the second non-spill pipe 247) (step S720).

[0084] After the user has redone the piping connections, the user presses the completion button 710, which is included in the piping connection prompt screen 700 (see Figure 21) displayed on the display unit 123 of the print control device 100 (step S730).

[0085] After step S730 is completed, the process returns to step S340 or step S400. In this regard, if there is no change in the second ink level position in step S370, the process returns to step S340, and if there is no change in the first ink level position in step S410, the process returns to step S400.

[0086] The results of the judgments made in steps S500, S600, and S700 are displayed on the display unit 123 of the print control device 100. In other words, the result of the judgment on whether or not the piping connections are made correctly is displayed on the display unit 123. Therefore, the user can quickly determine whether or not the piping connections are made correctly after replacing the print head.

[0087] In this embodiment, steps S100 and S110 are used to perform a pre-check of the ink level position, steps S200 and S210 are used to perform an ink level sensor inspection, step S310 is used to perform a message output step, step S330 is used to accept that the replacement is complete, steps S340, S350, S360, and S370 are used to determine the supply side connection status, step S400 is used to start the ink circulation, and steps S410, S500, S600, S610, S700, and S800 are used to determine the connection status. Furthermore, step S340 realizes a second ink level position storage step, step S350 realizes a pressurizing step, steps S360 and S370 realize a second ink level position confirmation step, step S410 realizes a first ink level position confirmation step, and steps S600 and S610 realize an ink level position reconfirmation step.

[0088] <7. Effects> According to this embodiment, after the user has finished replacing the head 240, a determination is made as to whether the piping connections, including the connection between the ink discharge pipe 244 and the recovery branch pipe 540, and the connection between the ink inlet pipe 246 and the supply branch pipe 530, are correctly made, based on the ink level position (ink level height) in the recovery tank 51 and the supply tank 52. Even if ink circulation in the circulation path starts, if there is a problem with the piping connections, the ink level position will not change. Therefore, with the configuration of this embodiment, it is possible to detect abnormalities in the piping connections without printing on the printing medium. Furthermore, since abnormalities in the piping connections can be detected before printing on the printing medium, the wasteful consumption of ink and printing medium is suppressed. In this way, it is possible to contribute to the achievement of the SDGs (Sustainable Development Goals). As described above, according to this embodiment, it is possible to provide a head replacement method for an inkjet printing apparatus that can detect abnormalities in the piping connections without printing. Furthermore, according to this embodiment, when an abnormality occurs due to head replacement, it is possible to quickly identify the cause of the abnormality (defective part). Specifically, it becomes possible to identify which of the following is malfunctioning: the connection between the ink discharge pipe 244 and the recovery branch pipe 540, the connection between the ink inlet pipe 246 and the supply branch pipe 530, the first liquid level sensor 511, the second liquid level sensor 521, the recovery control valve 541, or the supply control valve 542.

[0089] <8. Variation> The following describes modifications of the above embodiment.

[0090] <8.1 First variation> Figure 22 is a flowchart showing the procedure for head replacement in the first modified example of the above embodiment. In this modified example, after the start of the head replacement process, the circulation of ink in the circulation channel is first stopped (step S300). Then, the same processes as in the above embodiment, from steps S310 to S360, are performed. In step S370, it is determined whether the ink level detected in step S360 is lower than the ink level stored in step S340. If the ink level detected in step S360 is lower than the ink level stored in step S340, the process proceeds to step S400. On the other hand, if the ink level detected in step S360 is not lower than the ink level stored in step S340, it is determined that there is some kind of abnormality (step S375), and the head replacement process is temporarily terminated.

[0091] In step S400, a single ink flow is performed to the new head. While the single ink flow is being performed to the new head, the first ink level is continuously monitored, and it is determined whether or not there is a change in the first ink level (step S410). If there is a change in the first ink level, it is determined that the head replacement was performed successfully (step S500), and this head replacement process ends. On the other hand, if there is no change in the first ink level, it is determined that there is some kind of abnormality (step S415), and the head replacement process ends for the time being.

[0092] If any abnormality is detected in step S375 or step S415, the cause of the abnormality will be identified and corrected (for example, by a service technician, repairing or replacing the equipment), after which the head replacement process will be restarted from the appropriate step.

[0093] In this modified example, a message output step is implemented in step S310, a replacement completion acceptance step is implemented in step S330, a supply side connection status determination step is implemented in steps S340, S350, S360, and S370, an ink circulation start step is implemented in step S400, and connection status determination steps are implemented in steps S410, S415, and S500. Furthermore, a second ink level position storage step is implemented in step S340, a pressurization step is implemented in step S350, a second ink level position confirmation step is implemented in steps S360 and S370, and a first ink level position confirmation step is implemented in step S410.

[0094] As described above, in this modified example, the processes of steps S100 to S230 (see Figure 16) in the above embodiment are not provided. In other words, in this modified example, the process of circulating ink to the head to be replaced (the old head) before stopping the circulation of ink in the circulation channel (step S300) to check for any abnormalities in the valve or liquid level sensor is not performed. Also, in this modified example, the processes of steps S600 to S800 (see Figure 17) in the above embodiment are not provided. In other words, in this modified example, when the ink liquid level position does not change normally after replacing the head 240, the process of circulating ink to the head not to be replaced to check whether there is an abnormality in the liquid level sensor or an abnormality in the piping connection is not performed.

[0095] According to this modified version, it is not possible to quickly identify the cause of any abnormalities that occur during head replacement, but it is possible to determine whether or not the head replacement was performed correctly without printing.

[0096] <8.2 Second variation> Figure 23 is a flowchart showing the procedure for head replacement in a second modified example of the above embodiment. In this modified example, after the start of the head replacement process, ink is first circulated to the head to be replaced (the old head) (step S100). Then, while the ink is circulating to the head to be replaced, the first ink level and the second ink level are continuously checked, and it is determined whether or not there is a change in both the first and second ink level (step S110). If there is a change in both the first and second ink level, the process proceeds to step S300. On the other hand, if there is no change in at least one of the first and second ink level, it is determined that there is an abnormality in the ink level sensor or the valve corresponding to the head to be replaced (step S115), and the head replacement process is terminated. The process from step S300 onward is the same as in the first modified example. However, if there is a change in both the first and second ink level positions in step S110, it is determined that there is no abnormality in the valves corresponding to the head to be replaced (recovery control valve 541 and supply control valve 542). In this case, in step S375, it is determined that there is an abnormality in the second liquid level sensor 521, and in step S415, it is determined that there is an abnormality in the first liquid level sensor 511. If it is determined in step S115 that there is an abnormality in the liquid level sensor or the valve corresponding to the head to be replaced, the cause of the abnormality is identified and corrected (for example, repair or replacement of the equipment) by a service technician, and then the head replacement process is restarted from step S100.

[0097] In this modified example, steps S100 and S110 are used to perform a pre-check of the ink level position, step S310 is used to perform a message output step, step S330 is used to perform a replacement completion acceptance step, steps S340, S350, S360, and S370 are used to perform a supply side connection status determination step, step S400 is used to perform an ink circulation start step, and steps S410, S415, and S500 are used to perform a connection status determination step. Furthermore, step S340 is used to perform a second ink level position storage step, step S350 is used to perform a pressurization step, steps S360 and S370 are used to perform a second ink level position confirmation step, and step S410 is used to perform a first ink level position confirmation step.

[0098] As described above, in this modified example, the processes of steps S600 to S800 (see Figure 17) in the above embodiment are not provided. In other words, in this modified example, when the ink level position does not change normally after replacing the head 240, the process of circulating ink to the head that is not to be replaced to check whether there is a problem with the ink level sensor or a problem with the piping connection is not performed.

[0099] According to this modified version, it becomes possible to rule out the possibility that the valve is the cause of an abnormality when one occurs after the head is replaced. Also, similar to the first modified version described above, it is not possible to quickly identify the cause of the abnormality that occurred during the head replacement, but it becomes possible to determine whether the head replacement was performed correctly without printing.

[0100] <9. Others> The present invention is not limited to the above embodiments (including modifications), and can be implemented in various modified forms without departing from the spirit of the invention. For example, in the above embodiments (including modifications), one head was replaced at a time, but the present invention is also valid in cases where multiple heads (e.g., two) are replaced at a time. In this case, the multiple heads become the "heads to be replaced" in the present invention. Furthermore, for example, the above embodiments illustrate the configuration of an inkjet printing apparatus 10 that performs color printing, but the present invention can also be applied when an inkjet printing apparatus that performs monochrome printing is used. [Explanation of Symbols]

[0101] 2… Head unit 10…Inkjet printing equipment 19…Head replacement support program 20…printing mechanism 24…Printing Department 25…Cleaning mechanism 40…Head holding plate 51... Recovery Tank 52…Supply tank 53…Supply piping 54… Recovery piping 55... Refrigeration piping 100…Printing control device 123...Display section 200... Printing machine body 240, 240(1)~240(5)...head (print head) 244... Ink discharge piping 245...First non-spill (first connector) 246... Ink inflow piping 247...Second non-spill (second connector) 511...First liquid level sensor 512...Second liquid level sensor 530, 530(1)~530(5)... Supply branch piping 540, 540(1)~540(5)... Recovery branch piping 541... Recovery control valve 542... Supply control valve

Claims

1. An inkjet printing apparatus comprising a plurality of heads for ejecting ink toward a printing medium, a head holding plate for holding the plurality of heads, and an ink supply mechanism for supplying ink to the plurality of heads, wherein a head replacement method is used to replace some of the plurality of heads, namely the heads to be replaced, The ink supply mechanism includes a supply tank for storing ink to be supplied to the plurality of heads, a recovery tank for storing ink recovered from the plurality of heads, a supply pipe forming a flow path for ink supplied from the supply tank to the plurality of heads, a recovery pipe forming a flow path for ink recovered from the plurality of heads to the recovery tank, a return pipe for returning ink from the recovery tank to the supply tank, a supply branch pipe forming a flow path for ink flowing from the supply pipe to each head, and a recovery branch pipe forming a flow path for ink flowing from each head to the recovery pipe. Each head is Ink discharge piping and A first connector for connecting the ink discharge pipe and the recovery branch pipe, Ink inlet piping and A second connector for connecting the ink inlet pipe and the supply branch pipe, Includes, A circulation path is formed through the supply tank, the supply piping, the supply branch piping, the ink inlet piping, the ink discharge piping, the recovery branch piping, the recovery piping, the recovery tank, and the return piping, through which the ink circulates. The head replacement method described above is: A piping removal step includes removing the ink inlet piping included in the head to be replaced from the supply branch piping and removing the ink discharge piping included in the head to be replaced from the recovery branch piping, A head removal step of removing the head to be replaced from the head retaining plate, A head mounting step involves attaching a new head to be used in place of the head to be replaced to the head holding plate, A piping connection step involves connecting the ink discharge piping included in the new head to the recovery branch piping via a first connector, and connecting the ink inflow piping included in the new head to the supply branch piping via a second connector, After the head mounting step and the piping connection step, an ink circulation start step is performed to start the circulation of ink in the circulation channel, After the ink circulation start step, a connection status determination step is performed to determine whether the piping connections, including the connection of the ink discharge pipe and the recovery branch pipe via the first connector and the connection of the ink inlet pipe and the supply branch pipe via the second connector, have been correctly made in the piping connection step, based on the ink level position representing the height of the ink level in at least one of the recovery tank and the supply tank. A method for replacing a head, characterized by including the following:

2. The connection status determination step includes a first ink level position confirmation step of continuously checking a first ink level position that represents the height of the ink level in the recovery tank. The head replacement method according to claim 1, characterized in that in the connection status determination step, if there is a change in the first ink level position confirmed in the first ink level position confirmation step, it is determined that the piping connection is made correctly.

3. In the ink circulation start step, ink circulation in the circulation channel is started so that ink is supplied only to the new head among the plurality of heads. The head replacement method according to claim 2, characterized in that in the first ink level position confirmation step, the first ink level position is continuously confirmed while the ink is circulating in the circulation channel so that ink is supplied only to the new head among the plurality of heads.

4. The ink supply mechanism includes a first liquid level sensor for detecting the first ink liquid level position, The connection status determination step includes an ink level position reconfirmation step in which, if there is no change in the first ink level position confirmed in the first ink level position confirmation step, the ink is circulated in the circulation channel so that ink is supplied only to the non-replacement target heads, which are the heads among the plurality of heads that have not been replaced, and the first ink level position is continuously confirmed. The head replacement method according to claim 2, characterized in that in the connection status determination step, if there is a change in the first ink level confirmed in the ink level reconfirmation step, it is determined that there is an abnormality in the connection between the ink discharge pipe and the recovery branch pipe via the first connector, and if there is no change in the first ink level confirmed in the ink level reconfirmation step, it is determined that there is an abnormality in the first liquid level sensor.

5. The head replacement method according to claim 2, characterized in that, after the head mounting step and the piping connection step, and before the ink circulation start step, a supply-side connection state determination step is included, in which, with the circulation path being such that only ink flows from the supply tank to the ink inlet pipe via the supply pipe and the supply branch pipe, the connection between the ink inlet pipe and the supply branch pipe via the second connector is determined based on a second ink level position representing the height of the ink level in the supply tank.

6. The supply side connection status determination step is: A second ink level position storage step, which stores the second ink level position when the supply tank is vented to the atmosphere, After the second ink level position storage step, a pressurizing step is performed to pressurize the inside of the supply tank, A second ink level position confirmation step is performed after the pressurization step, in which the second ink level position is confirmed when the supply tank is vented to the atmosphere. Includes, The head replacement method according to claim 5, characterized in that in the supply side connection status determination step, if the second ink level confirmed in the second ink level confirmation step is lower than the second ink level stored in the second ink level storage step, it is determined that the connection between the ink inlet pipe and the supply branch pipe via the second connector is correct.

7. The ink supply mechanism includes a second liquid level sensor for detecting the second ink liquid level position, The connection status determination step includes an ink level position reconfirmation step in which, unless the second ink level position confirmed in the second ink level position confirmation step is lower than the second ink level position stored in the second ink level position storage step, ink is continuously checked while circulating ink in the circulation channel so that ink is supplied only to the non-replaceable heads, which are the heads among the plurality of heads that have not been replaced. The head replacement method according to claim 6, characterized in that in the connection status determination step, if there is a change in the second ink level confirmed in the ink level reconfirmation step, it is determined that there is an abnormality in the connection between the ink inlet pipe and the supply branch pipe via the second connector, and if there is no change in the second ink level confirmed in the ink level reconfirmation step, it is determined that there is an abnormality in the second liquid level sensor.

8. Prior to the piping removal step and the head removal step, the ink level position pre-check step includes continuously checking the ink level position while circulating ink in the circulation channel so that ink is supplied only to the head to be replaced among the plurality of heads, The head replacement method according to claim 1, characterized in that the piping removal step, the head removal step, the head installation step, the piping connection step, the ink circulation start step, and the connection status determination step are executed only when there is a change in the ink liquid level position confirmed in the ink liquid level position pre-confirmation step.

9. The ink supply mechanism includes a liquid level sensor for detecting the ink level, a supply control valve for controlling the flow of ink in the supply branch pipe, and a recovery control valve for controlling the flow of ink in the recovery branch pipe. The head replacement method includes a liquid level sensor inspection step in which, if there is no change in the ink liquid level position confirmed in the ink liquid level pre-confirmation step, ink is supplied only to the non-replacement target heads, which are among the multiple heads that were not replaced, while the ink is circulated in the circulation channel and the ink liquid level position is continuously checked. The head replacement method according to claim 8, characterized in that if there is a change in the ink level position confirmed in the liquid level sensor inspection step, it is determined that there is an abnormality in the supply control valve or the recovery control valve corresponding to the head to be replaced, and if there is no change in the ink level position confirmed in the liquid level sensor inspection step, it is determined that there is an abnormality in the liquid level sensor.

10. The ink supply mechanism includes, as the liquid level sensor, a first liquid level sensor that detects a first ink liquid level position representing the height of the ink liquid level in the recovery tank, and a second liquid level sensor that detects a second ink liquid level position representing the height of the ink liquid level in the supply tank. In the ink level position pre-confirmation step and the liquid level sensor inspection step, the first ink level position and the second ink level position are confirmed as the ink level position. If there is no change in the first ink level position confirmed in the ink level position pre-check step, and there is a change in the first ink level position confirmed in the ink level sensor inspection step, then it is determined that there is an abnormality in the recovery control valve corresponding to the head to be replaced. If there is no change in the first ink level position confirmed in the ink level position pre-check step, and there is no change in the first ink level position confirmed in the liquid level sensor inspection step, then it is determined that there is an abnormality in the first liquid level sensor. If there is no change in the second ink level position confirmed in the ink level position pre-check step, and there is a change in the second ink level position confirmed in the ink level sensor inspection step, then it is determined that there is an abnormality in the supply control valve corresponding to the head to be replaced. The head replacement method according to claim 9, characterized in that if there is no change in the second ink level position confirmed in the ink level position pre-confirmation step, and there is no change in the second ink level position confirmed in the liquid level sensor inspection step, a determination is made that there is an abnormality in the second liquid level sensor.

11. The ink supply mechanism includes a first liquid level sensor that detects a first ink level position representing the height of the ink liquid in the recovery tank, and a second liquid level sensor that detects a second ink level position representing the height of the ink liquid in the supply tank. The head replacement method according to claim 1, characterized in that in the connection status determination step, it is determined whether the piping connection is made correctly based on at least one of the first ink level position detected by the first liquid level sensor and the second ink level position detected by the second liquid level sensor.

12. The inkjet printing apparatus includes a control device that controls the operation of the plurality of heads and the ink supply mechanism, The aforementioned pipe removal step, head removal step, head installation step, and pipe connection step are performed by an operator. The head replacement method according to any one of claims 1 to 11, characterized in that the ink circulation start step and the connection status determination step are performed by the control device.

13. The control device has a display unit, The head replacement method according to claim 12, characterized in that in the connection status determination step, the determination result of whether the piping connection is made correctly is displayed on the display unit.

14. An inkjet printing apparatus comprising: a plurality of heads for ejecting ink toward a printing medium; an ink supply mechanism for supplying ink to the plurality of heads; and a control device for controlling the operation of the plurality of heads and the ink supply mechanism, The ink supply mechanism includes a supply tank for storing ink to be supplied to the plurality of heads, a recovery tank for storing ink recovered from the plurality of heads, a supply pipe forming a flow path for ink supplied from the supply tank to the plurality of heads, a recovery pipe forming a flow path for ink recovered from the plurality of heads to the recovery tank, a return pipe for returning ink from the recovery tank to the supply tank, a supply branch pipe forming a flow path for ink flowing from the supply pipe to each head, and a recovery branch pipe forming a flow path for ink flowing from each head to the recovery pipe. Each head is Ink discharge piping and A first connector for connecting the ink discharge pipe and the recovery branch pipe, Ink inlet piping and A second connector for connecting the ink inlet pipe and the supply branch pipe, Includes, A circulation path is formed through the supply tank, the supply piping, the supply branch piping, the ink inlet piping, the ink discharge piping, the recovery branch piping, the recovery piping, the recovery tank, and the return piping, through which the ink circulates. The control device is A message output step that outputs a message prompting the replacement of the head, A replacement completion confirmation step that receives input indicating that the head replacement has been completed, An ink circulation start step is performed to initiate the circulation of ink in the circulation channel so that ink is supplied to the new head, which is the head after replacement. A connection status determination step, based on the ink level position representing the height of the ink level in at least one of the recovery tank and the supply tank, determines whether the piping connections, including the connection between the ink discharge pipe and the recovery branch pipe included in the new head via the first connector and the connection between the ink inlet pipe and the supply branch pipe included in the new head via the second connector, are properly made. An inkjet printing apparatus characterized by performing the following in this order.

15. In an inkjet printing apparatus comprising a plurality of heads for ejecting ink toward a printing medium, an ink supply mechanism for supplying ink to the plurality of heads, and a control device for controlling the operation of the plurality of heads and the ink supply mechanism, a computer included in the control device, A message output step that outputs a message prompting the replacement of the head, A replacement completion confirmation step that receives input indicating that the head replacement has been completed, A replacement work result inspection step to check whether the head replacement was performed correctly, and Make it run, The ink supply mechanism includes a supply tank for storing ink to be supplied to the plurality of heads, a recovery tank for storing ink recovered from the plurality of heads, a supply pipe forming a flow path for ink supplied from the supply tank to the plurality of heads, a recovery pipe forming a flow path for ink recovered from the plurality of heads to the recovery tank, a return pipe for returning ink from the recovery tank to the supply tank, a supply branch pipe forming a flow path for ink flowing from the supply pipe to each head, and a recovery branch pipe forming a flow path for ink flowing from each head to the recovery pipe. Each head is Ink discharge piping and A first connector for connecting the ink discharge pipe and the recovery branch pipe, Ink inlet piping and A second connector for connecting the ink inlet pipe and the supply branch pipe, Includes, A circulation path is formed through the supply tank, the supply piping, the supply branch piping, the ink inlet piping, the ink discharge piping, the recovery branch piping, the recovery piping, the recovery tank, and the return piping, through which the ink circulates. The aforementioned replacement work result inspection step is: An ink circulation start step is performed to initiate the circulation of ink in the circulation channel so that ink is supplied to the new head, which is the head after replacement. A connection status determination step, based on the ink level position representing the height of the ink level in at least one of the recovery tank and the supply tank, determines whether the piping connections, including the connection between the ink discharge pipe and the recovery branch pipe included in the new head via the first connector and the connection between the ink inlet pipe and the supply branch pipe included in the new head via the second connector, are properly made. A head replacement support program characterized by including the following:

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