Inkjet recording device and maintenance method and program of inkjet recording device

Abstract

To provide an inkjet recording device capable of more effectively suppressing clogging of an ink flow path, and a maintenance method and a program of the inkjet recording device.SOLUTION: An inkjet recording device includes: an image formation part that has an inkjet head, and in which ink in the image formation part is heated to a temperature higher than an outside temperature of the image formation part; a main tank that stores ink supplied to the image formation part; heating means that heats an ink flow path connecting the main tank and the image formation part; clogging suppression means that performs a clogging suppression operation for suppressing ink clogging in the ink flow path by a method different from heating of the ink; and control means that causes the clogging suppression means to perform the clogging suppression operation.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an inkjet printing apparatus, a maintenance method for an inkjet printing apparatus, and a program. [Background technology]

[0002] Conventionally, there are inkjet recording devices that record images on a recording medium by ejecting ink onto the recording medium from the nozzles of an inkjet head. Some of these inkjet recording devices are configured to supply ink from an external main tank to an image forming unit equipped with an inkjet head. The ink in the image forming unit is heated to a temperature higher than the ambient temperature to increase its fluidity. However, because the ink flow path from the main tank to the image forming unit is exposed to the ambient temperature, clogging of the ink in the ink flow path is likely to occur due to a decrease in the viscosity of the ink. In response to this issue, Patent Document 1 discloses a configuration in which the ink in the ink flow path is heated by a heating unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-133629 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even if the above-mentioned conventional technology is applied, the upstream side of the ink flow path from the heating unit, i.e., the main tank side, is not heated, so that this part is still prone to clogging. Furthermore, there are cases where simply heating the ink is not enough to prevent clogging of the ink flow path.

[0005] An object of the present invention is to provide an inkjet recording apparatus, a maintenance method for an inkjet recording apparatus, and a program therefor that can more effectively prevent clogging of ink flow paths. [Means for solving the problem]

[0006] In order to achieve the above object, the inkjet recording apparatus according to claim 1 comprises: an image forming unit having an inkjet head, wherein ink in the image forming unit is heated to a temperature higher than the ambient temperature of the image forming unit; a main tank that stores the ink to be supplied to the image forming unit; a heating unit for heating an ink flow path connecting the main tank and the image forming unit; a clogging prevention unit that performs a clogging prevention operation to prevent clogging of the ink in the ink flow path by a method other than heating the ink; a control means for causing the clogging suppression means to perform the clogging suppression operation; Equipped with.

[0007] The invention described in claim 2 is the inkjet recording apparatus described in claim 1, a detection unit for detecting clogging of the ink in the ink flow path, The control means causes the clogging prevention means to perform the clogging prevention operation when the detection means detects the clogging of the ink.

[0008] The invention described in claim 3 is the inkjet recording apparatus described in claim 2, the image forming unit includes a sub-tank that temporarily stores the ink supplied from the main tank, The detecting means detects the amount of ink that flows into the subtank per predetermined time, and detects ink clogging based on the result of the detection of the amount of ink that flows into the subtank.

[0009] The invention described in claim 4 is the inkjet recording apparatus described in claim 2, The detecting means detects the pressure of the ink in the ink flow path, and detects the ink clogging based on the detected pressure.

[0010] The invention described in claim 5 is the inkjet recording apparatus described in claim 1, The control means causes the heating means to heat the ink flow path when causing the clogging prevention means to perform the clogging prevention operation.

[0011] The invention described in claim 6 is the inkjet recording apparatus described in claim 1, the clogging prevention means has a vibration unit that vibrates the ink flow path, The clogging prevention operation includes an operation in which the vibration unit vibrates the ink flow path.

[0012] The invention described in claim 7 is the inkjet recording apparatus described in claim 1, the clogging prevention means has an agitation unit that agitates the ink in the ink flow path, The clogging prevention operation includes an operation in which the agitation unit agitates the ink in the ink flow path.

[0013] The invention described in claim 8 is the inkjet recording apparatus described in claim 1, the clogging prevention unit has a liquid feed pump that feeds the ink in the main tank to the image forming unit, The clogging prevention operation includes an operation in which the liquid feed pump intermittently feeds the ink.

[0014] The invention described in claim 9 is the inkjet recording apparatus described in claim 8, When the liquid supply pump intermittently supplies the ink during the clogging prevention operation, the amount of ink delivered per unit time by the liquid supply pump is greater than the amount of ink delivered per unit time by the liquid supply pump when the clogging prevention operation is not performed.

[0015] The invention described in claim 10 is the inkjet recording apparatus described in claim 4, the clogging prevention unit has a circulation flow path that returns ink in the image forming unit to the ink flow path, The clogging prevention operation includes an operation of circulating the ink in the circulation flow path.

[0016] The invention described in claim 11 is the inkjet recording apparatus described in claim 1, The ink includes a wax.

[0017] In order to achieve the above object, the invention of a maintenance method for an inkjet recording apparatus according to claim 12 comprises: In an inkjet recording device comprising: an image forming unit having an inkjet head, wherein the ink in the image forming unit is heated to a temperature higher than the ambient temperature of the image forming unit; a main tank that stores the ink to be supplied to the image forming unit; a heating means that heats an ink flow path connecting the main tank and the image forming unit; and a clogging prevention means that performs a clogging prevention operation to prevent clogging of the ink in the ink flow path by a method other than heating the ink, the method includes a step of causing the clogging prevention means to perform the clogging prevention operation.

[0018] In order to achieve the above object, the invention of the program described in claim 13 is as follows: a main tank for storing the ink to be supplied to the image forming unit; a heating unit for heating an ink flow path connecting the main tank and the image forming unit; and a clogging prevention unit for performing a clogging prevention operation to prevent clogging of the ink in the ink flow path by a method other than heating the ink. a control means for causing the clogging suppression means to perform the clogging suppression operation; Function as. [Effects of the Invention]

[0019] According to the present invention, clogging of the ink flow path can be more effectively suppressed. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an inkjet recording apparatus. [Figure 2] FIG. 2 is a schematic diagram of the internal configuration of the head unit as viewed from the front. [Figure 3] FIG. 2 is a schematic diagram of a head unit as viewed from the conveyor belt side. [Figure 4] FIG. 2 is a schematic diagram illustrating a configuration of an ink supply mechanism. [Figure 5] FIG. 2 is a block diagram showing the main functional configuration of the inkjet printing apparatus. [Figure 6] 10 is a flowchart showing a control procedure for maintenance processing. [Figure 7] 10 is a flowchart showing a control procedure for a clogging detection process. [Figure 8] 10 is a flowchart showing another control procedure of the clogging detection process. [Figure 9] 10 is a flowchart showing a control procedure of clogging prevention processing when the first clogging prevention operation and / or the second clogging prevention operation is performed. [Figure 10] 10 is a flowchart showing a control procedure of clogging prevention processing when a third clogging prevention operation is performed. [Figure 11] 10 is a flowchart showing a control procedure of clogging prevention processing when a fourth clogging prevention operation is performed. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] (Configuration of Inkjet Recording Apparatus) 1 is a diagram showing a schematic configuration of an inkjet recording apparatus 1 according to an embodiment of the present invention. The inkjet recording apparatus 1 includes a transport section 10, a head unit 20 (image forming section), a main tank 41, and the like.

[0023] The transport unit 10 includes two transport rollers 101 and 102 that rotate around a rotation axis extending in the X direction in Fig. 1, and a ring-shaped transport belt 103 whose inner side is supported by the transport rollers 101 and 102. The transport roller 101 rotates in response to the operation of a transport motor (not shown), causing the transport belt 103 to move in a circular motion around the transport rollers 101 and 102. The transport unit 10 transports the recording medium M in the moving direction of the transport belt 103 (transport direction; Y direction in Fig. 1) as the transport belt 103 moves in a circular motion with the recording medium M placed on the transport surface of the transport belt 103.

[0024] The recording medium M may be, for example, a sheet of paper cut to a certain size. The recording medium M is supplied onto a conveyor belt 103 by a paper feeder (not shown), and ink is ejected from the head unit 20 to record an image. The recording medium M is then discharged from the conveyor belt 103 to a predetermined paper discharge section. Note that a long medium such as roll paper may also be used as the recording medium M. In addition to paper such as plain paper or coated paper, various media that can fix ink that has landed on their surfaces, such as fabric or sheet-like resin, may be used as the recording medium M.

[0025] The head units 20 eject ink at appropriate timing based on image data onto the recording medium M transported by the transport unit 10 to record an image. The inkjet recording device 1 of this embodiment is equipped with four head units 20, each corresponding to one of four colors of ink: yellow (Y), magenta (M), cyan (C), and black (K). The four head units 20 are arranged at predetermined intervals in the order of Y, M, C, and K from the upstream side in the transport direction of the recording medium M. The number of head units 20 can be changed depending on the number of colors used, and may be three or less or five or more.

[0026] FIG. 2 is a schematic diagram of the internal configuration of the head unit 20 when viewed from the front. FIG. 3 is a schematic diagram of the head unit 20 as viewed from the conveyor belt 103 side. The head unit 20 has a plurality of inkjet heads 22 (eight in this embodiment), each of which is provided with a plurality of nozzles N that eject ink. Each inkjet head 22 has, corresponding to each nozzle N, a pressure chamber (channel) that stores ink, a piezoelectric element provided on the wall of the pressure chamber, and an electrode to which a voltage signal (drive signal) having a drive waveform that deforms the piezoelectric element is supplied. When a drive signal is applied to the electrode, the pressure chamber deforms in response to the drive signal, changing the pressure within the pressure chamber. In response to this change in pressure, ink is ejected from the nozzles N that communicate with the pressure chamber. In each inkjet head 22, the plurality of nozzles N are arranged at equal intervals in the X direction. In this embodiment, each inkjet head 22 has four nozzle rows. Each nozzle row is made up of nozzles N that are linearly arranged at equal intervals in the X direction. The four nozzle rows of each inkjet head 22 are offset from one another in the X direction so that the nozzles N do not overlap in the X direction. The number of nozzle rows that the inkjet head 22 has is not limited to four, but may be three or less, or five or more.

[0027] In the head unit 20, the eight inkjet heads 22 are arranged in a staggered pattern so that the arrangement range of the nozzles N in the X direction is continuous. The arrangement range of the nozzles N included in the head unit 20 in the X direction covers the width of the X direction of an area of ​​the recording medium M on which an image can be recorded. The head unit 20 is used in a fixed position when forming an image. The head unit 20 forms an image by a single pass method by ejecting ink from the nozzles N to each position at a predetermined interval in the transport direction as the recording medium M is transported.

[0028] 2, the inkjet head 22 has an inlet 221 through which ink flows in and an outlet 222 through which ink flows out. A portion of the ink that enters the inkjet head 22 from the inlet 221 is ejected from the nozzles N. A portion of the ink that is not ejected from the nozzles N is discharged from the outlet 222 to the outside of the inkjet head 22, recovered, and reused.

[0029] The ink ejected from the nozzles N of the inkjet head 22 is a phase-change ink that changes phase between a gel state and a sol (liquid) state depending on the temperature. The phase-change ink is converted into a sol by heating it to a predetermined first phase-change temperature or higher. The phase-change ink is also converted into a gel by cooling it to a predetermined second phase-change temperature or higher. The phase-change ink is obtained by adding a gelling agent to the ink. In this embodiment, wax is used as the gelling agent. The inkjet head 22 ejects ink from the nozzles N that has been heated to a first phase-change temperature or higher by the wax melting unit 25 (see FIG. 5) and the in-unit heating unit 26 (see FIG. 5) and has been converted into a sol state. After being ejected from the nozzles N and landing on the recording medium M, the ink quickly changes to a gel state by cooling to room temperature and dropping below the second phase-change temperature. The ink composition is not limited to the above. For example, an ultraviolet curing agent may be added to the ink to form an ultraviolet curable ink that is cured by exposure to ultraviolet light.

[0030] Next, we will explain the ink supply mechanism 2 of the inkjet recording apparatus 1. The ink supply mechanism 2 is a mechanism for supplying ink to the inkjet heads 22 in the inkjet recording apparatus 1. Fig. 4 is a schematic diagram showing the configuration of the ink supply mechanism 2. In Fig. 4, the ink supply mechanism 2 corresponding to one head unit 20 is extracted and shown. In the other head units 20, ink is supplied to the inkjet heads 22 by ink supply mechanisms 2 of similar configuration.

[0031] The ink supply mechanism 2 includes a main tank 41 provided outside the head unit 20. The main tank 41 and the head unit 20 are connected by an external flow path 71 (ink flow path). The ink supply mechanism 2 includes a flow path heating unit 42 (heating means) provided in the external flow path 71, a liquid feed pump 43 (clogging prevention means), a temperature detection unit 44, a vibration unit 45 (clogging prevention means), a stirring unit 46 (clogging prevention means), and a pressure detection unit 47 (detection means).

[0032] The flow path heating unit 42 heats the external flow path 71 and the ink flowing within the external flow path 71. It is preferable that the flow path heating unit 42 be able to heat as long an area of ​​the external flow path 71 as possible. In FIG. 4, the area to be heated by the flow path heating unit 42 is indicated by a dashed line. The liquid feed pump 43 sends out ink stored in the main tank 41 toward the head unit 20. The liquid feed pump 43 sends out ink at a timing and in an amount according to a control signal sent from the control unit 30 (see FIG. 5). The liquid feed pump 43 can be, for example, a positive displacement reciprocating pump such as a diaphragm pump. The temperature detection unit 44 detects the temperature of the ink flowing within the external flow path 71 and outputs the detection result to the control unit 30.

[0033] The vibration unit 45 performs a vibration operation to vibrate the external flow path 71 at a timing and intensity according to a control signal transmitted from the control unit 30. The vibration operation by the vibration unit 45 includes an operation to periodically apply a force to the external flow path 71. The external flow path 71 is made of a material that deforms due to the force received from the vibration unit 45. The vibration unit 45 may be provided with a mechanism that periodically moves in a direction perpendicular to the extension direction of the external flow path 71, for example. However, the configuration of the vibration unit 45 and the method of vibrating the external flow path 71 are not limited to this.

[0034] The stirring unit 46 performs a stirring operation to stir the ink in the external flow path 71 at a timing and with an intensity according to a control signal sent from the control unit 30. The stirring unit 46 includes, for example, a stirring chamber provided midway through the external flow path 71 and a propeller that rotates within the stirring chamber. The stirring operation of the stirring unit 46 includes an operation to rotate the propeller according to the control signal. However, the configuration of the stirring unit 46 and the method of stirring the ink are not limited to this.

[0035] The pressure detection unit 47 detects the pressure of the ink in the external flow path 71 and outputs the detection result to the control unit 30. In this embodiment, the pressure detection units 47 are provided at two locations in the external flow path 71. The pressure loss in the external flow path 71 can be calculated from the differential pressure between the pressures detected by the pressure detection units 47.

[0036] The ink supply mechanism 2 includes a first sub-tank 231 (sub-tank), a second sub-tank 232, a wax melting unit 25, a circulation pump 27, a first solenoid valve 281, a second solenoid valve 282, a third solenoid valve 283, and internal flow paths 72 to 75, which are provided within the head unit 20. The internal flow path 72 connects the external flow path 71 to the first sub-tank 231. The internal flow path 73 connects the first sub-tank 231 to the second sub-tank 232. The internal flow path 74 connects the second sub-tank 232 to the inlet 221 of the inkjet head 22. The internal flow path 75 connects the outlet 222 of the inkjet head 22 to the first sub-tank 231. Therefore, the head unit 20 is provided with a first circulation flow path C1 that passes through the first sub-tank 231, the internal flow path 73, the second sub-tank 232, the internal flow path 74, the inkjet head 22, and the internal flow path 75 before returning to the first sub-tank 231. With this configuration, ink is supplied from the first sub-tank 231 to the inkjet head 22 via the second sub-tank 232. In addition, ink that is not ejected from the inkjet head 22 is collected in the first sub-tank 231 via the internal flow path 75.

[0037] The wax melting unit 25 is provided midway through the internal flow path 72. The wax melting unit 25 heats the ink flowing through the internal flow path 72 to melt the wax contained in the ink. In other words, the wax melting unit 25 heats the ink to a temperature equal to or higher than the melting point of the wax.

[0038] The first sub-tank 231 stores ink supplied from the main tank 41 via the wax melting unit 25. The first sub-tank 231 is provided with a liquid level detection unit 241 (detection means) that detects the height of the ink liquid surface in the first sub-tank 231. The liquid level detection unit 241 outputs data related to the detected height to the control unit 30.

[0039] A circulation pump 27 and a first solenoid valve 281 are provided midway along the internal flow path 73. The circulation pump 27 sends ink from the first sub-tank 231 to the second sub-tank 232 at a timing and at a sending amount according to a control signal sent from the control unit 30. The circulation pump 27 can be, for example, a positive displacement reciprocating pump such as a diaphragm pump. The first solenoid valve 281 is provided downstream of the circulation pump 27. The first solenoid valve 281 opens and closes according to a control signal sent from the control unit 30, thereby switching between opening and closing the internal flow path 73.

[0040] The second subtank 232 is a small tank chamber that temporarily stores ink supplied from the first subtank 231. The second subtank 232 is connected to the inlet 221 of the inkjet head 22 via an internal flow path 74. The second subtank 232 may be connected to two or more inkjet heads 22. The second subtank 232 is sealed, and its pressure is adjusted to a constant negative pressure relative to atmospheric pressure by an exhaust pump (not shown) or the like. This draws ink in the head unit 20 toward the second subtank 232, preventing unintended ink leakage from the nozzles N of the inkjet head 22. Note that the back pressure of the second subtank 232 may be controlled by the head head difference between the ink level in the second subtank 232 and the ink level in the inkjet head 22. The second subtank 232 is provided with a liquid level detection unit 242 that detects the ink level in the second subtank 232. The liquid level detection unit 242 outputs data related to the detected level to the control unit 30. When ink is discharged from the nozzles N of the inkjet head 22 and consumed, ink is supplied from the second sub-tank 232 to the inkjet head 22 to make up for the consumed amount.

[0041] An internal flow path 75 is connected to the outlet 222 of the inkjet head 22. A second solenoid valve 282 is provided in the internal flow path 75. The second solenoid valve 282 opens and closes in accordance with a control signal transmitted from the control unit 30, thereby switching between opening and closing the internal flow path 75.

[0042] The ink supply mechanism 2 is provided with a reflux flow path 76 that returns ink in the internal flow path 73 to the external flow path 71. The reflux flow path 76 branches off from the internal flow path 73 between the circulation pump 27 and the first solenoid valve 281. The other end of the reflux flow path 76 is connected to a region of the external flow path 71 that is to be heated by the flow path heating unit 42. This forms a second circulation flow path C2 (circulation flow path) that includes the external flow path 71, the internal flow paths 72, the internal flow paths 73, and the reflux flow path 76. A third solenoid valve 283 is provided in the reflux flow path 76. The third solenoid valve 283 opens and closes in accordance with a control signal transmitted from the control unit 30, thereby switching between opening and closing the reflux flow path 76 and the second circulation flow path C2.

[0043] Figure 5 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1. In the explanation of Figure 5, the configuration explained with reference to Figure 4 will be omitted. The inkjet recording apparatus 1 comprises a transport drive unit 11 provided in a transport unit 10, a head unit 20, a control unit 30 (control means, computer, clogging prevention means, detection means), an operation display unit 50, and a communication unit 60. The various units of the inkjet recording apparatus 1 are connected via a signal transmission path such as a bus.

[0044] The transport driver 11 supplies a drive signal to the transport motor of the transport roller 101 based on a control signal sent from the controller 30, and moves the transport belt 103 in a circular motion at a predetermined speed and timing.

[0045] The control unit 30 is a hardware processor having a CPU 31 (Central Processing Unit), RAM 32 (Random Access Memory), and storage unit 33. The CPU 31 reads various control programs 331 and setting data stored in the storage unit 33, and executes the programs 331 to perform various arithmetic processing. In this way, the CPU 31 comprehensively controls the overall operation of the inkjet recording apparatus 1. The RAM 32 provides the CPU 31 with working memory space and stores temporary data. The storage unit 33 has non-volatile memory and stores the programs 331, print jobs (image recording commands) input via the communication unit 60, image data related to the print jobs, various setting data, and the like. The storage unit 33 may be, for example, a hard disk drive (HDD) or a solid state drive (SSD).

[0046] In addition to the components shown in FIG. 4, the head unit 20 also includes a head control unit 21 and an internal unit heating unit 26. The head control unit 21 outputs various control signals and image data to a head drive unit provided in the inkjet head 22 at timings according to control signals sent from the control unit 30. The control signals include signals that designate drive waveforms related to the drive signals. The head drive unit supplies drive signals to electrodes of the inkjet head 22 in accordance with the control signals and image data input from the head control unit 21. This causes the piezoelectric elements to deform, causing ink to be ejected from the nozzles N.

[0047] The internal unit heating section 26 heats the ink inside the head unit 20. The internal unit heating section 26 may be, for example, a rubber heater attached to the outer wall surfaces of the first sub-tank 231, the second sub-tank 232, and the internal flow paths 72 to 75. However, the attachment position and configuration of the internal unit heating section 26 are not limited to this as long as it is possible to heat the ink inside the head unit 20. The ink inside the head unit 20 is heated to a temperature higher than the ambient temperature outside the head unit 20 by the internal unit heating section 26 and the wax melting section 25 described above.

[0048] The operation display unit 50 includes a display device such as a liquid crystal display, and an input device such as operation keys and a touch panel overlaid on the screen of the display device. The operation display unit 50 displays, on the display device, information such as status information of the inkjet recording apparatus 1, and notifications or warnings to the user. The operation display unit 50 also converts user input operations on the input device into operation signals and outputs the signals to the control unit 30.

[0049] The communication unit 60 is a communication interface that controls communication operations with external devices. The communication unit 60 acquires data related to print jobs from external devices under the control of the control unit 30, and also transmits status information and the like to external devices.

[0050] (Operation of inkjet recording device) Next, the operation of the inkjet recording apparatus 1 will be described, focusing on the ink supplying operation in the ink supply mechanism 2 and the operation related to the maintenance of the inkjet recording apparatus 1.

[0051] When forming an image according to a print job, the control unit 30 of the inkjet recording apparatus 1 opens the first solenoid valve 281 and the second solenoid valve 282 to allow ink to flow through the first circulation flow path C1. The control unit 30 also closes the third solenoid valve 283 to prevent ink from flowing back from the internal flow path 73 to the external flow path 71. In this state, the control unit 30 forms an image on the recording medium M by ejecting ink from the nozzles N of the inkjet head 22 based on image data and the like related to the print job. When the amount of ink stored in the second sub-tank 232 falls below a refill reference amount, the control unit 30 activates the circulation pump 27 to send ink from the first sub-tank 231 to the second sub-tank 232. When the amount of ink stored in the first sub-tank 231 falls below the refill reference amount, the control unit 30 activates the liquid feed pump 43 to supply ink from the main tank 41 to the first sub-tank 231.

[0052] As described above, because the main tank 41 and the external flow path 71 are provided outside the head unit 20, the ink in the external flow path 71 is likely to be at a lower temperature than the ink in the head unit 20. The lower the temperature, the more likely the ink is to thicken. Furthermore, because the ink of this embodiment contains wax as a gelling agent, the lower the temperature, the more likely the wax components are to separate, and the wax components are likely to accumulate in the external flow path 71. Furthermore, foreign matter in the ink, including ink components, is likely to accumulate in the curved portions of the external flow path 71. Furthermore, foreign matter is also likely to accumulate in areas where the flow path diameter of the external flow path 71 changes. Due to these factors, the external flow path 71 is more likely to become clogged due to the accumulation of foreign matter, including ink components, than the internal flow paths 72 to 75 in the head unit 20.

[0053] Therefore, in the inkjet recording apparatus 1 of this embodiment, the flow path heating unit 42 performs a flow path heating operation to heat the ink in the external flow path 71, thereby suppressing clogging of the external flow path 71. Here, "suppressing clogging" includes not only restoring an existing clogging state to an unclogged state or a state where the clogging has been alleviated, but also preventing clogging from occurring in the first place. Furthermore, "suppressing clogging" includes making the ink state less susceptible to clogging, in other words, improving the non-uniformity of the ink components.

[0054] In the flow path heating operation, the flow path heating unit 42 heats the ink in the external flow path 71 to a predetermined reference temperature or higher. Here, the reference temperature may be, for example, a temperature equal to or higher than the melting point of the wax contained in the ink. The reference temperature may also be a temperature equal to or higher than the temperature at which the ink is ejected from the inkjet head 22, i.e., the temperature at which the ink is used. The reference temperature may also be a temperature at which the ink has a predetermined viscosity or lower, for example, a temperature equal to or higher than the first phase change temperature at which the ink transitions to a sol state. The flow path heating operation can prevent clogging of the external flow path 71 due to a decrease in ink temperature and an increase in ink viscosity. However, the flow path heating operation is less effective in preventing clogging upstream of the region to be heated by the flow path heating unit 42, i.e., on the main tank 41 side. Furthermore, simply heating the ink in the external flow path 71 may not be sufficient to prevent clogging of the external flow path 71.

[0055] Therefore, in the inkjet recording apparatus 1 of this embodiment, in addition to the flow path heating operation, a clogging prevention operation is performed. The clogging prevention operation is an operation in which clogging of the external flow path 71 is prevented by a method other than heating the ink, using a clogging prevention means provided in the inkjet recording apparatus 1. The clogging prevention operation includes the following first to fourth clogging prevention operations.

[0056] The first clogging prevention operation is an operation in which the vibration unit 45 as a clogging prevention means and the control unit 30 vibrate the external flow path 71. By vibrating the external flow path 71 with the vibration unit 45, foreign matter and deposits that cause clogging can be released from the inner wall surface of the external flow path 71 and washed away together with the ink.

[0057] The second clogging prevention operation is an operation in which the ink in the external flow path 71 is stirred by the stirring unit 46 as a clogging prevention means and the control unit 30. By stirring the ink in the external flow path 71 with the stirring unit 46, foreign matter and deposits that may cause clogging can be released within the ink and washed away together with the ink. This prevents clogging of the external flow path 71.

[0058] The third clogging prevention operation is an operation in which ink is intermittently pumped through the external flow path 71 by the liquid pump 43 as a clogging prevention unit and the control unit 30. Here, intermittent ink pumping refers to a first period during which the liquid pump 43 pumps ink and a second period during which the liquid pumping is stopped, repeated at a predetermined interval. Note that the second period may be performed at a smaller liquid pumping rate than the first period. Furthermore, the amount of ink pumped per unit time by the liquid pump 43 during intermittent ink pumping through the third clogging prevention operation may be greater than the amount of ink pumped per unit time by the liquid pump 43 during normal liquid pumping without the third clogging prevention operation. Here, the unit time is sufficiently longer than the repetition period of the first and second periods. The intermittent ink pumping causes the ink pressure to change intermittently. This allows foreign matter and deposits that could cause clogging to be released within the ink and washed away along with the ink. This prevents clogging of the external flow path 71.

[0059] The fourth clogging prevention operation is an operation of circulating ink in the second circulation flow path C2 as a clogging prevention means. According to the fourth clogging prevention operation, a portion of the ink heated in the head unit 20 is returned to the external flow path 71 by the second circulation flow path C2. This makes it possible to increase the temperature of the ink in the external flow path 71. Also, it is possible to increase the amount of ink sent through the external flow path 71. As a result, clogging of the external flow path 71 is suppressed.

[0060] Note that one of the first to fourth clogging prevention operations may be selected and executed, or two or more may be executed in combination. That is, the clogging prevention operation may include one or two or more of the first to fourth clogging prevention operations. Furthermore, if some of the first to fourth clogging prevention operations are not executed, the clogging prevention means corresponding to the not-executed clogging prevention operation may be omitted. For example, if the first clogging prevention operation is not executed, the vibration unit 45 may be omitted. Furthermore, if the second clogging prevention operation is not executed, the stirring unit 46 may be omitted. Furthermore, if the fourth clogging prevention operation is not executed, the return flow path 76 may be omitted.

[0061] The inkjet recording apparatus 1 executes a maintenance operation that includes any one of the first to fourth clogging prevention operations. The following describes the maintenance processing that the control unit 30 executes to realize this maintenance operation.

[0062] 6 is a flowchart showing the control procedure of the maintenance process. This maintenance process is executed at a predetermined timing while the inkjet recording apparatus 1 is in operation. When the maintenance process is started, the control unit 30 opens the first solenoid valve 281 and the second solenoid valve 282 and closes the third solenoid valve 283 (step S101). This opens the first circulation flow path C1 and closes the reflux flow path 76. Thereafter, the control unit 30 executes a clogging detection process (step S102).

[0063] FIG. 7 is a flowchart showing the control procedure for the clogging detection process. When the clogging detection process is started, the control unit 30 activates the liquid supply pump 43 to start liquid supply and supply ink from the liquid supply pump 43 to the first subtank 231 (step S201). The control unit 30 detects the amount of ink inflow into the first subtank 231 per unit time (step S202). Here, the control unit 30 repeatedly acquires the detection result of the liquid level height by the liquid level detection unit 241 of the first subtank 231 and detects the amount of ink inflow per unit time based on the rate of rise of the liquid level. The control unit 30 determines whether the detected amount of ink inflow is less than a reference amount of ink inflow (step S203). The reference amount of ink inflow is preset and stored in the memory unit 33. The reference amount of ink inflow may be the amount of ink inflow per unit time when a clog occurs in the external flow path 71, or a value obtained by adding a predetermined value to the value of the inflow amount. If the control unit 30 determines that the detected inflow rate is less than the reference inflow rate (YES in step S203), it determines that a clog has occurred in the external flow path 71 (step S204). If the control unit 30 determines that the detected inflow rate is equal to or greater than the reference inflow rate (NO in step S203), it determines that a clog has not occurred in the external flow path 71 (step S205). After step S204 or S205 is completed, the control unit 30 stops the liquid supply pump 43 to terminate the liquid supply (step S206), and the process returns to the maintenance process of FIG. 6. In this way, in the clog detection process of FIG. 7, an ink clog in the external flow path 71 is detected based on the detection result of the ink inflow rate per unit time into the first sub-tank 231. Here, the liquid level detection unit 241 and the control unit 30 correspond to a detection means for detecting an ink clog in the external flow path 71.

[0064] Instead of the clogging detection process of FIG. 7, a clogging detection process shown in FIG. 8 may be executed. In the clogging detection process of FIG. 8, steps S202 and S203 in the clogging detection process of FIG. 7 are replaced with steps S202a and S203a, respectively. Differences from the clogging detection process of FIG. 7 will be described below. In the clogging detection process of FIG. 8, when the liquid feed pump 43 starts feeding liquid, the control unit 30 detects a pressure loss in the external flow path 71 (step S202a). Here, the control unit 30 acquires ink pressure data from the pressure detection units 47 at two locations and detects the pressure loss from the differential pressure. The control unit 30 determines whether the detected pressure loss is equal to or greater than a reference value (step S203a). The reference value is set in advance and stored in the memory unit 33. The reference value may be the value of the pressure loss in the external flow path 71 when a clog occurs in the external flow path 71, or a value obtained by subtracting a predetermined value from the pressure value. If the control unit 30 determines that the detected pressure loss is equal to or greater than the reference value ("YES" in step S203a), it determines that a clog has occurred in the external flow path 71 (step S204). If the control unit 30 determines that the detected pressure loss is less than the reference value ("NO" in step S203), it determines that a clog has not occurred in the external flow path 71 (step S205). In this way, in the clog detection process of FIG. 8, an ink clog in the external flow path 71 is detected based on the ink pressure in the external flow path 71. Here, the pressure detection unit 47 and the control unit 30 correspond to the detection means. In the above, the pressure loss is calculated from the detection results of the pressures at two locations. Alternatively, the presence or absence of a clog may be determined based on the comparison result between the ink pressure at a certain position in the external flow path 71 and the set value of the liquid delivery pressure by the liquid delivery pump 43.

[0065] When the clogging detection process (step S102) of FIG. 6 is completed, the control unit 30 determines whether a clogging has been detected in the external flow path 71 (step S103). If it is determined that a clogging has been detected ("YES" in step S103), the control unit 30 determines whether the liquid volume in the first subtank 231 is less than a reference liquid volume (step S104). Here, the reference liquid volume is a value obtained by subtracting a certain liquid volume from the liquid volume when the first subtank 231 is full. The certain liquid volume is the amount of ink that can flow into the first subtank 231 during the clogging prevention process (step S107) described below. In other words, the reference liquid volume is determined so that a sufficient amount of ink can flow into the first subtank 231 during the clogging prevention process. If it is determined that the liquid volume in the first subtank 231 is equal to or greater than the reference liquid volume ("NO" in step S104), the control unit 30 executes steps S105 and S106 to reduce the liquid volume in the first subtank 231. In step S105, the control unit 30 operates the circulation pump 27 to purge ink from the inkjet head 22 (step S105). That is, by operating the circulation pump 27, the control unit 30 supplies ink from the first sub-tank 231 to the inkjet head 22 via the second sub-tank 232 at a higher pressure than during image formation. This forces ink to be ejected from the nozzles N of the inkjet head 22. In step S105, the control unit 30 may close the second solenoid valve 282 to close the internal flow path 75, thereby creating a state in which the ink pressure in the inkjet head 22 is likely to increase. The control unit 30 again determines whether the liquid volume in the first sub-tank 231 is less than the reference liquid volume (step S106). If it is determined that the liquid volume is equal to or greater than the reference liquid volume (YES in step S106), the control unit 30 returns the process to step S105. If it is determined that the amount of liquid in the first sub-tank 231 is less than the reference amount of liquid (YES in step S104 or S106), the control unit 30 proceeds to step S107. Note that even at the start of the clogging detection process of FIGS. 7 and 8, the processes of steps S104 to S106 may be performed so that the amount of liquid in the first sub-tank 231 is less than the reference amount of liquid.

[0066] In step S107, the control unit 30 executes a clogging prevention process to cause the clogging prevention means to perform the clogging prevention operation. That is, when a clogging of the external flow path 71 is detected ("YES" in step S103) and there is sufficient free space in the first sub-tank 231, the control unit 30 causes the clogging prevention means to perform the clogging prevention operation. Here, the control unit 30 executes one of the clogging prevention processes shown in Figures 9 to 11. Which clogging prevention process to execute is set in advance based on a user operation or the like.

[0067] 9 is a flowchart showing the control procedure of the clogging prevention process when the first clogging prevention operation and / or the second clogging prevention operation is performed. When the clogging prevention process is started, the control unit 30 causes the flow path heating unit 42 to start the flow path heating operation (step S301). The control unit 30 repeatedly determines whether the temperature of the ink in the external flow path 71 is equal to or higher than the reference temperature based on the output data from the temperature detection unit 44 (step S302). If the control unit 30 determines that the temperature of the ink in the external flow path 71 is equal to or higher than the reference temperature ("YES" in step S302), the control unit 30 starts vibrating the external flow path 71 and / or stirring the ink in the external flow path 71 (step S303). Here, when the control unit 30 performs the first clogging prevention operation, the control unit 30 sends a control signal to the vibration unit 45, causing the vibration unit 45 to vibrate the external flow path 71. Furthermore, when the control unit 30 executes the second clogging prevention operation, it sends a control signal to the stirring unit 46, thereby causing the stirring unit 46 to stir the ink in the external flow path 71. Whether vibration or stirring is to be executed is set in advance based on the user's operation or the like.

[0068] The control unit 30 operates the liquid feed pump 43 to start feeding ink from the liquid feed pump 43 to the first subtank 231 (step S304). The control unit 30 repeatedly determines whether the first subtank 231 is full based on output data from the liquid level detection unit 241 (step S305). If it determines that the first subtank 231 is full ("YES" in step S305), the control unit 30 stops the liquid feed pump 43 to end the feeding of ink from the liquid feed pump 43 to the first subtank 231 (step S306). The control unit 30 also ends the vibration operation of the vibration unit 45 on the external flow path 71 and the agitation operation of the agitation unit 46 on the ink in the external flow path 71 (step S307). The control unit 30 also ends the flow path heating operation of the flow path heating unit 42 (step S308). Thereafter, the control unit 30 ends the clogging prevention process and returns the process to the maintenance process of FIG.

[0069] FIG. 10 is a flowchart showing the control procedure of the clogging prevention process when the third clogging prevention operation is performed. Steps S401, S402, S404, and S406 in the clogging prevention process of FIG. 10 are the same as steps S301, S302, S305, and S308 in the clogging prevention process of FIG. 9, respectively. The following describes the differences from the clogging prevention process of FIG. 9. In the clogging prevention process of FIG. 10, if the control unit 30 determines that the temperature of the ink in the external flow path 71 is equal to or higher than the reference temperature ("YES" in step S402), the control unit 30 starts intermittent driving of the liquid feed pump 43 (step S403). Here, the control unit 30 sends a control signal to the liquid feed pump 43 so that the liquid feed pump 43 repeatedly executes a first period in which it feeds liquid and a second period in which it stops feeding liquid at a predetermined cycle.

[0070] Thereafter, if it is determined that the first sub-tank 231 is full ("YES" in step S404), the control unit 30 ends the intermittent driving of the liquid feed pump 43, thereby ending the feeding of ink from the liquid feed pump 43 to the first sub-tank 231 (step S405). When the control unit 30 ends the flow path heating operation by the flow path heating unit 42 (step S406), it ends the clogging prevention process and returns the process to the maintenance process of FIG.

[0071] FIG. 11 is a flowchart showing the control procedure of the clogging prevention process when the fourth clogging prevention operation is performed. Steps S501, S502, S505, S506, and S509 in the clogging prevention process of FIG. 11 are the same as steps S301, S302, S304, S305, and S308 in the clogging prevention process of FIG. 9, respectively. The following describes the differences from the clogging prevention process of FIG. 9. In the clogging prevention process of FIG. 11, if the control unit 30 determines that the temperature of the ink in the external flow path 71 is equal to or higher than the reference temperature ("YES" in step S502), the control unit 30 closes the first solenoid valve 281 and opens the third solenoid valve 283 (step S503). This closes the liquid supply path from the first sub-tank 231 to the second sub-tank 232 and opens the second circulation flow path C2. The control unit 30 operates the circulation pump 27 to start feeding the ink and circulates the ink in the second circulation flow path C2 (step S504). The control unit 30 also operates the liquid feed pump 43 to start feeding the ink from the liquid feed pump 43 to the first subtank 231 (step S505). As a result, the ink heated by the flow path heating unit 42 is fed from the main tank 41 to the first subtank 231, and the ink in the first subtank 231 is returned to the external flow path 71 by the second circulation flow path C2. Here, the control unit 30 controls the amount of ink stored in the first subtank 231 to increase over time by making the amount of ink fed by the liquid feed pump 43 greater than the amount of ink fed by the circulation pump 27.

[0072] Thereafter, if it is determined that the first subtank 231 is full ("YES" in step S506), the control unit 30 stops the liquid feed pump 43 and the circulation pump 27, and ends the supply of ink from the liquid feed pump 43 to the first subtank 231 (step S507). The control unit 30 opens the first solenoid valve 281 and closes the third solenoid valve 283 (step S508). This opens the first circulation flow path C1 and closes the return flow path 76. When the control unit 30 ends the flow path heating operation by the flow path heating unit 42 (step S509), it ends the clogging prevention process and returns the process to the maintenance process of FIG. 6.

[0073] 6 (step S107), the control unit 30 determines whether or not an operation to turn off the power of the inkjet recording apparatus 1 has been performed (step S108). If it is determined that such an operation has not been performed ("NO" in step S108), the control unit 30 returns the process to step S102. If it is determined that such an operation has been performed ("YES" in step S108), the control unit 30 ends the maintenance process.

[0074] (effect) As described above, the inkjet recording apparatus 1 according to this embodiment includes the head unit 20, the main tank 41, the flow path heating unit 42, a clogging suppression unit, and the control unit 30. The head unit 20 has an inkjet head 22, and the ink therein is heated to a temperature higher than the ambient temperature of the head unit 20. The main tank 41 stores ink to be supplied to the head unit 20. The flow path heating unit 42 heats the external flow path 71 connecting the main tank 41 and the head unit 20. The clogging suppression unit performs a clogging suppression operation to suppress ink clogging in the external flow path 71 by a method other than heating the ink. The control unit 30 controls the clogging suppression unit to perform the clogging suppression operation. With this configuration, by combining the ink heating by the flow path heating unit 42 and the clogging suppression operation by the clogging suppression unit, clogging in the external flow path 71 can be effectively suppressed. In other words, the external flow path 71 can be effectively restored to an unclogged state and the occurrence of clogging can be prevented. For example, clogging can be suppressed by the clogging suppression operation even in the external flow path 71 upstream of the flow path heating unit 42 where ink is not heated by the flow path heating unit 42. Furthermore, even in the range to be heated by the flow path heating unit 42, even if clogging is not sufficiently suppressed by heating alone, clogging can be effectively suppressed by combining the clogging suppression operation.

[0075] The inkjet recording apparatus 1 also includes a detection means for detecting ink clogging in the external flow path 71. When the detection means detects ink clogging, the control unit 30 causes the clogging prevention means to perform a clogging prevention operation. This allows the external flow path 71 to be cleared of clogging if it is clogged. Furthermore, by using the detection means, the clogging prevention operation can be performed at an appropriate timing.

[0076] The head unit 20 also includes a first sub-tank 231 that temporarily stores ink supplied from the main tank 41. A liquid level detection unit 241 as a detection means and the control unit 30 detect the amount of ink that flows into the first sub-tank 231 per predetermined time, and detects ink clogging based on the detection result of the inflow amount. This makes it possible to appropriately detect clogging of the external flow path 71 using a simple method based on the inflow amount.

[0077] Furthermore, the pressure detection unit 47 and the control unit 30 as detection means detect the ink pressure in the external flow path 71 and detect ink clogging based on the detected pressure. This makes it possible to appropriately detect clogging of the external flow path 71 using a simple method based on the ink pressure in the external flow path 71.

[0078] Furthermore, when the control unit 30 causes the clogging prevention means to perform the clogging prevention operation, it causes the flow path heating unit 42 to heat the external flow path 71. This makes it possible to effectively prevent clogging of the external flow path 71 by combining the flow path heating operation and the clogging prevention operation.

[0079] The clogging prevention means may also have a vibration unit 45 that vibrates the external flow path 71. In this case, the clogging prevention operation includes the operation of the vibration unit 45 vibrating the external flow path 71. By vibrating the external flow path 71 with the vibration unit 45, foreign matter and deposits that may cause clogging can be released from the inner wall surface of the external flow path 71 and washed away together with the ink. This effectively prevents clogging of the external flow path 71.

[0080] The clogging prevention means may also have an agitation unit 46 that agitates the ink in the external flow path 71. In this case, the clogging prevention operation includes an operation in which the agitation unit 46 agitates the ink in the external flow path 71. By agitating the ink in the external flow path 71 with the agitation unit 46, foreign matter and deposits that could cause clogging can be liberated within the ink and washed away together with the ink. This effectively prevents clogging of the external flow path 71.

[0081] The clogging prevention means may also include a liquid supply pump 43 that sends ink from the main tank 41 to the head unit 20. In this case, the clogging prevention operation includes the liquid supply pump 43 intermittently sending ink. The intermittent ink supply causes the ink pressure to change intermittently. This allows foreign matter and deposits that could cause clogging to be liberated within the ink and washed away along with the ink. This effectively prevents clogging of the external flow path 71.

[0082] Furthermore, the amount of ink delivered per unit time by the liquid delivery pump 43 when the liquid delivery pump 43 intermittently delivers ink during the clogging prevention operation may be greater than the amount of ink delivered per unit time by the liquid delivery pump 43 when the clogging prevention operation is not performed. This more effectively flushes out foreign matter and deposits that may cause clogging along with the ink. This effectively prevents clogging of the external flow path 71.

[0083] The clogging prevention means may also have a second circulation flow path C2 that returns ink in the head unit 20 to the external flow path 71. In this case, the clogging prevention operation includes an operation of circulating ink in the second circulation flow path C2. This allows a portion of the ink heated in the head unit 20 to be returned to the external flow path 71 by the second circulation flow path C2. This makes it possible to increase the temperature of the ink in the external flow path 71. Furthermore, it is possible to increase the amount of ink sent through the external flow path 71. As a result, clogging of the external flow path 71 is effectively prevented.

[0084] The ink may also contain wax. In this case, when the temperature of the ink drops, the wax components separate and tend to accumulate in the external flow path 71. However, by combining the flow path heating operation and the clogging prevention operation, the accumulation of the wax components can be effectively prevented. Therefore, clogging of the external flow path 71 can be effectively prevented.

[0085] The maintenance method for the inkjet recording apparatus 1 according to this embodiment also includes a step of causing the clogging prevention means to perform a clogging prevention operation. The program 331 according to this embodiment also causes the control unit 30 to function as a control means for causing the clogging prevention means to perform the clogging prevention operation. These steps effectively prevent clogging of the external flow path 71.

[0086] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the image forming unit is not limited to the head unit 20. The image forming unit can have any configuration that includes an inkjet head 22, receives ink from an external main tank 41, and heats the ink inside to a temperature higher than the ambient temperature. For example, the image forming unit may have a housing that houses multiple head units 20.

[0087] 6, the clogging prevention process (step S107) is executed when a clogging is detected in the clogging detection process (step S102) ("YES" in step S103), but this is not limiting. Steps S102 and S103 may be omitted, and the clogging prevention operation may be executed preventatively when a clogging is not detected. For example, the clogging prevention operation may be executed when the cumulative operating time of the inkjet recording apparatus 1 reaches a predetermined time, or when the cumulative number of printed sheets reaches a predetermined number.

[0088] The ink may also contain a first wax having a melting point at a first temperature and a second wax having a melting point at a second temperature higher than the first temperature. In this case, the wax melting unit 25, the unit interior heating unit 26, and the flow path heating unit 42 heat the ink to a temperature equal to or higher than the second temperature. Note that the flow path heating unit 42 may be positioned as a preliminary heating means, and may heat the ink to a temperature equal to or higher than the first temperature and lower than the second temperature.

[0089] In the above embodiment, the recording medium M is conveyed by the conveying unit 10 including the conveying belt 103, but the present invention is not limited to this. The conveying unit 10 may be configured to convey the recording medium M by holding it on the outer circumferential surface of a rotating conveying drum, for example.

[0090] Furthermore, in the above embodiment, the inkjet recording apparatus 1 of a single pass type has been described as an example, but the present invention may also be applied to an inkjet recording apparatus that records an image while scanning the recording head.

[0091] Although several embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0092] 1. Inkjet recording device 2 Ink supply mechanism 10 Conveying section 20 Head unit (image forming unit) 22 Inkjet head 231 1st Subtank (Subtank) 232 Second Subtank 241 Liquid level detection unit (detection means) 242 Liquid level detector 27 Circulation Pump 30 Control unit (clogging prevention means, detection means) 41 Main Tank 42 Flow path heating section (heating means) 43 Liquid transfer pump (clogging prevention means) 45 Vibration unit (clogging prevention means) 46 Stirring section (clogging prevention means) 47 Pressure detection unit (detection means) 71 External flow path (ink flow path) 72~75 Internal flow path 76 Reflux channel 281 First solenoid valve 282 Second solenoid valve 283 Third solenoid valve C1 First circulation channel C2 Second circulation channel (circulation channel) M Recording medium N nozzle

Claims

1. an image forming unit having an inkjet head, wherein ink in the image forming unit is heated to a temperature higher than the ambient temperature of the image forming unit; a main tank that stores the ink to be supplied to the image forming unit; a heating unit for heating an ink flow path connecting the main tank and the image forming unit; a clogging prevention unit that performs a clogging prevention operation to prevent clogging of the ink in the ink flow path by a method other than heating the ink; a control means for causing the clogging suppression means to perform the clogging suppression operation; An inkjet recording apparatus comprising:

2. a detection unit for detecting clogging of the ink in the ink flow path, the control means causes the clogging prevention means to perform the clogging prevention operation when the detection means detects the clogging of the ink; The inkjet recording apparatus according to claim 1 .

3. the image forming unit includes a sub-tank that temporarily stores the ink supplied from the main tank, the detecting means detects an amount of ink flowing into the subtank per predetermined time, and detects ink clogging based on the result of the detection of the amount of ink flowing into the subtank. The inkjet recording apparatus according to claim 2 .

4. the detecting means detects the pressure of the ink in the ink flow path and detects the ink clogging based on the detected pressure. The inkjet recording apparatus according to claim 2 .

5. the control unit causes the heating unit to heat the ink flow path when causing the clogging prevention unit to perform the clogging prevention operation. The inkjet recording apparatus according to claim 1 .

6. the clogging prevention means has a vibration unit that vibrates the ink flow path, the clogging prevention operation includes an operation of the vibration unit vibrating the ink flow path. The inkjet recording apparatus according to claim 1 .

7. the clogging prevention means has an agitation unit that agitates the ink in the ink flow path, the clogging prevention operation includes an operation of the stirring unit stirring the ink in the ink flow path. The inkjet recording apparatus according to claim 1 .

8. the clogging prevention unit has a liquid feed pump that feeds the ink in the main tank to the image forming unit, the clogging prevention operation includes an operation of the liquid feed pump intermittently feeding the ink. The inkjet recording apparatus according to claim 1 .

9. an amount of ink delivered by the liquid delivery pump per unit time when the liquid delivery pump intermittently delivers the ink during the clogging prevention operation is greater than an amount of ink delivered by the liquid delivery pump per unit time when the clogging prevention operation is not performed; The inkjet recording apparatus according to claim 8.

10. the clogging prevention unit has a circulation flow path that returns ink in the image forming unit to the ink flow path, the clogging prevention operation includes an operation of circulating the ink in the circulation flow path. The inkjet recording apparatus according to claim 4 .

11. The ink comprises a wax. The inkjet recording apparatus according to claim 1 .

12. an inkjet recording apparatus including an image forming unit having an inkjet head, the image forming unit having ink therein heated to a temperature higher than the ambient temperature of the image forming unit; a main tank for storing the ink to be supplied to the image forming unit; a heating means for heating an ink flow path connecting the main tank and the image forming unit; and a clogging prevention means for performing a clogging prevention operation to prevent clogging of the ink in the ink flow path by a method other than heating the ink, the method comprising: a step of causing the clogging prevention means to perform the clogging prevention operation; A maintenance method for an inkjet recording apparatus.

13. a main tank for storing the ink to be supplied to the image forming unit; a heating unit for heating an ink flow path connecting the main tank and the image forming unit; and a clogging prevention unit for performing a clogging prevention operation to prevent clogging of the ink in the ink flow path by a method other than heating the ink. a control means for causing the clogging suppression means to perform the clogging suppression operation; A program that functions as a

Images