Inkjet printing device

Abstract

To provide a technique that can keep an ink discharge surface in a capped state as long as possible, so as to reduce loads on an operator, in sequentially maintaining a plurality of head units.SOLUTION: An input part receives a first instruction including an instruction for switching a first ink discharge surface of a first discharge head from a capped state into a decapped state, outputs a first input signal, receives a second instruction including an instruction for switching a second ink discharge surface of a second discharge head from a capped state into a decapped state and outputs a second input signal. A control part can execute: a step in which when the first input signal is inputted (a) so that it is sensed that the first head unit has been moved from a first driving position to a first maintenance position, the first ink discharge surface is switched from the capped state to the decapped state; and a step in which when the second input signal is inputted (b) so that it is sensed that the second head unit has been moved from a second driving position to a second maintenance position, the second ink discharge surface is switched from the capped state to the decapped state.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to an inkjet printing apparatus that performs inkjet printing on a printing medium such as paper. [Background technology]

[0002] Conventionally, various maintenance procedures are performed on inkjet printing devices to prevent clogging of nozzles that eject ink. For example, to prevent the nozzles from drying out while printing is stopped, the nozzles are sometimes covered with caps to isolate and seal the ink ejection surface, including the nozzles, from the external atmosphere. A method for performing such nozzle maintenance is described, for example, in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-136396 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses a maintenance unit (9) for performing maintenance on an image forming apparatus. The maintenance unit (9) includes a cap (91) for capping the nozzle surface (124), a wiper member (94) for wiping the nozzle surface (124), a suction pump (97) connected to the cap (91), and a waste liquid tank (98) connected to the suction pump (97) (paragraphs 0037 and 0039). The maintenance unit (9) is also provided so as to be movable between a maintenance position where the cap (91) caps the nozzle surface (124) and a retracted position where the maintenance unit (9) is retracted from the maintenance position (paragraph 0043, Figures 5(a) and 5(b)).

[0005] In recent years, many devices have been used that allow an operator to input into an input screen the operation of covering the ink ejection surface, including the nozzles, with a cap to isolate and seal it from the external atmosphere (capping), and the operation of separating the cap from the ink ejection surface to expose it to the external atmosphere (decap).With such devices, an operator can specify the target head on the input screen and input "capping" or "decapping," which automatically operates the cap for the specified head.

[0006] To prevent the nozzles from drying out while printing is stopped, it is desirable to keep the ink ejection surface, including the nozzles, sealed with a cap as much as possible while the nozzles are not being wiped (i.e., in a "capped state"). To do this, it is desirable for an operator to specify the head with the nozzles on the input screen immediately before wiping the nozzles, and input that the nozzles will be "decapped (i.e., set to a "decapped state")." However, having to go to the input screen and input information every time a different head is being maintained places a heavy burden on the operator.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a technology that can reduce the burden on workers while keeping the ink ejection surface, including the nozzles, in a capped state for as long as possible when sequentially performing maintenance on multiple heads each having multiple nozzles. [Means for solving the problem]

[0008] To solve the above problems, a first invention of the present application provides an inkjet printing device that performs inkjet printing on a print medium, and includes a device housing, a first head unit, a second head unit, a first slider, a second slider, a first detection unit, a second detection unit, an input unit, and a control unit. The first head unit includes a first ejection head having a first ink ejection surface facing downward and formed with first ejection ports that eject a first ink, a first cap that can cap the first ink ejection surface, and a first movement mechanism that can switch between a capped state in which the first ink ejection surface is isolated from the external atmosphere by the first cap and a decapped state in which the capped state is released. The second head unit includes a second ejection head having a second ink ejection surface facing downward and formed with second ejection ports that eject a second ink, a second cap that can cap the second ink ejection surface, and a second movement mechanism that can switch between a capped state in which the second ink ejection surface is isolated from the external atmosphere by the second cap and a decapped state in which the capped state is released. The first slider supports the first head unit so that it can slide between a first drive position in the internal space of the device housing and a first maintenance position in the external space of the device housing. The second slider is provided separately from the first slider and supports the second head unit so that it can slide between a second drive position in the internal space of the device housing and a second maintenance position in the external space of the device housing. The first detection unit detects that the first head unit has moved between the first drive position and the first maintenance position, and outputs a first detection signal. The second detection unit detects that the second head unit has moved between the second drive position and the second maintenance position, and outputs a second detection signal. The input unit receives a first command including a command to switch the first ink ejection surface from the capped state to the decapped state, and outputs a first input signal when the first command is received, and receives a second command including a command to switch the second ink ejection surface from the capped state to the decapped state, and outputs a second input signal when the second command is received.The control unit is electrically connected to each of the first ejection head, the first movement mechanism, the first detection unit, the second ejection head, the second movement mechanism, the second detection unit, and the input unit. The control unit is capable of executing the following steps: (a) when detecting that the first head unit has moved from the first drive position to the first maintenance position based on the first detection signal input from the first detection unit, with the first input signal input from the input unit, controlling the first movement mechanism to switch the first ink ejection surface from the capped state to the decapped state after a first predetermined time has elapsed; and (b) when detecting that the second head unit has moved from the second drive position to the second maintenance position based on the second detection signal input from the second detection unit, with the second input signal input from the input unit, controlling the second movement mechanism to switch the second ink ejection surface from the capped state to the decapped state after a second predetermined time has elapsed.

[0009] A second invention of the present application is the inkjet printing apparatus of the first invention, wherein after step a), when the control unit detects that the first head unit has moved from the first maintenance position to the first drive position based on the first detection signal input from the first detection unit, the control unit controls the first movement mechanism to switch the first ink ejection surface from the decapped state to the capped state.Furthermore, after step b), when the control unit detects that the second head unit has moved from the second maintenance position to the second drive position based on the second detection signal input from the second detection unit, the control unit controls the second movement mechanism to switch the second ink ejection surface from the decapped state to the capped state.

[0010] A third invention of the present application is the inkjet printing apparatus of the first or second invention, wherein when the control unit detects that the first head unit has moved from the first drive position to the first maintenance position based on the first detection signal input from the first detection unit in a state where the first input signal is not input from the input unit, the control unit recognizes this as an error and waits with the first ink ejection surface in the capped state.Furthermore, when the control unit detects that the second head unit has moved from the second drive position to the second maintenance position based on the second detection signal input from the second detection unit in a state where the second input signal is not input from the input unit, the control unit recognizes this as an error and waits with the second ink ejection surface in the capped state.

[0011] A fourth aspect of the present invention is the inkjet printing apparatus of any one of the first to third aspects, further comprising a first circulation path, a first circulation pump, a second circulation path, and a second circulation pump. The first circulation path includes a first supply tank that stores the first ink to be supplied to the first ejection head, a first recovery tank that stores the first ink recovered from the first ejection head, and a first return pipe that connects the first recovery tank and the first supply tank. The first circulation pump is inserted into the first return pipe and sends the first ink from the first recovery tank to the first supply tank via the first return pipe. The second circulation path includes a second supply tank that stores the second ink to be supplied to the second ejection head, a second recovery tank that stores the second ink recovered from the second ejection head, and a second return pipe that connects the second recovery tank and the second supply tank. The second circulation pump is inserted into the second return pipe and sends the second ink from the second recovery tank to the second supply tank via the second return pipe. The control unit is further electrically connected to each of the first circulation pump and the second circulation pump. When the control unit detects that the first head unit has moved from the first drive position to the first maintenance position, it stops driving the first circulation pump. When the control unit detects that the second head unit has moved from the second drive position to the second maintenance position, it stops driving the second circulation pump. [Effects of the Invention]

[0012] According to the first to fourth inventions of the present application, the ink ejection surface of the ejection head of the head unit undergoing maintenance is switched to a "decapped state" immediately before maintenance is performed on that head unit, thereby shortening the time that the ink ejection surface of the head unit undergoing maintenance is exposed to the external atmosphere. This makes it possible to prevent the ejection ports from drying out. In addition, since commands for switching multiple head units to a "decapped state" can be input together, the burden on workers can be reduced.

[0013] In particular, according to the second aspect of the present invention, immediately after completing maintenance and returning the head unit to the internal space of the device housing, the ink ejection surface of the returned head unit can be switched back to the "capped state." This further shortens the time that each ink ejection surface is exposed to the external atmosphere. As a result, drying of each ink ejection surface can be further suppressed.

[0014] In particular, according to the third aspect of the present invention, if a head unit other than the one intended to be pulled out into the external space is pulled out, it can be recognized as an error and subsequent work can be stopped.

[0015] In particular, according to the fourth aspect of the present invention, by stopping the circulation of ink, even if the head unit is pulled out to the external space, it is possible to prevent ink leakage from the ejection ports of the pulled-out head unit and air from being sucked into the ejection ports. This suppresses pressure changes on the ejection head and reduces the occurrence of damage. In addition, because the circulation of ink is stopped immediately before maintenance of each head unit is performed, it is possible to further prevent the ejection ports from drying out. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram conceptually illustrating the configuration of an inkjet printing device. [Figure 2] FIG. 2 is a perspective view schematically illustrating the configuration of a head unit. [Figure 3] FIG. 2 is a diagram conceptually illustrating the configuration of an ejection head and an ink supply unit of a head unit. [Figure 4] FIG. 2 is a bottom view of the ejection head and head holding plate of the head unit as viewed from below. [Figure 5] FIG. 2 is a diagram conceptually illustrating the positional relationship between a head unit and a housing of an inkjet printing device. [Figure 6] FIG. 2 is a side view schematically showing the configuration of a head unit and a slider. [Figure 7] FIG. 2 is a side view schematically showing the configuration of a head unit and a slider. [Figure 8] FIG. 2 is a block diagram showing connections between a control unit and each unit of the inkjet printing device. [Figure 9] 10 is a flowchart showing a procedure for performing maintenance on the head unit. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the components described in these embodiments are merely examples and are not intended to limit the scope of the present invention. Furthermore, in the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary to facilitate understanding.

[0018] <1. Configuration of inkjet printing device> FIG. 1 is a conceptual diagram showing the configuration of an inkjet printing apparatus 1 according to one embodiment of the present invention. This inkjet printing apparatus 1 is an inkjet printer that records characters and images on the surface of a long strip of continuous paper 10 by ejecting droplets of water-based ink from multiple head units 35 toward the continuous paper 10 while transporting the continuous paper 10. However, the long strip of continuous paper 10 is merely one example of a print medium. The print medium may be cut paper, or may be a substrate made of plastic film, cardboard, metal foil, or glass. In other words, the inkjet printing apparatus 1 may be any device that prints on a print medium using an inkjet method.

[0019] The inkjet printing device 1 has a transport unit 2, a printing unit 3, a device housing 4, a control unit 9, and an input unit 11. As will be described in detail below, the printing unit 3 has multiple (four in this embodiment) head units 35. The four head units 35 have the same configuration. Therefore, in the following description and drawings, when it is necessary to distinguish between these four head units 35, they will be referred to as "first head unit 35a," "second head unit 35b," "third head unit 35c," and "fourth head unit 35d" by adding sub-numbers a to d to the reference numeral "35," and when there is no need to distinguish between them, the sub-numbers will be omitted.

[0020] The inkjet printing device 1 is also provided with one ink supply unit 36, one slider 41 (see FIG. 5), and one detection unit 45 (see FIG. 5) corresponding to each of the four head units 35. The ink supply units 36 corresponding to the four head units 35 have the same configuration. Therefore, in the following description and drawings, when it is necessary to distinguish between these four ink supply units 36, sub-numbers a to d are added to the reference numeral "36" to refer to them as "first ink supply unit 36a," "second ink supply unit 36b," "third ink supply unit 36c," and "fourth ink supply unit 36d." When it is not necessary to distinguish between them, the sub-numbers are omitted. The sliders 41 corresponding to the four head units 35 have the same configuration. Therefore, in the following description and drawings, when it is necessary to distinguish between these four sliders 41, sub-numbers a to d are added to the reference numeral "41" and they are referred to as "first slider 41a," "second slider 41b," "third slider 41c," and "fourth slider 41d," and when it is not necessary to distinguish between them, the sub-numbers are omitted. Furthermore, the detection units 45 corresponding to the four head units 35 have the same configuration. Therefore, in the following description and drawings, when it is necessary to distinguish between these four detection units 45, sub-numbers a to d are added to the reference numeral "45" and they are referred to as "first detection unit 45a," "second detection unit 45b," "third detection unit 45c," and "fourth detection unit 45d," and when it is not necessary to distinguish between them, the sub-numbers are omitted.

[0021] The transport unit 2 is a mechanism that transports the continuous paper 10 in a transport direction that follows its longitudinal direction along a predetermined transport path. The continuous paper 10 is passed over multiple transport rollers 12. The continuous paper 10 is transported along a transport path formed by the multiple transport rollers 12. Each transport roller 12 rotates around an axis that extends in a direction (width direction) perpendicular to the transport direction, thereby guiding the continuous paper 10 downstream of the transport path. In addition, tension is applied to the continuous paper 10 in the transport direction. This prevents the continuous paper 10 from sagging or wrinkling during transport.

[0022] The printing unit 3 has a plurality of (four in this embodiment) head units 35 and a plurality of (four in this embodiment) ink supply units 36. As described above, the four head units 35 have the same configuration as each other. Also, as described above, the four ink supply units 36 have the same configuration as each other.

[0023] The four head units 35 are arranged at intervals from one another in the transport direction. Each of the four head units 35 ejects ink droplets from a nozzle 103 (see FIG. 3, described later) toward the surface (upper surface) of the continuous paper 10, which is being transported in the transport direction below the four head units 35. In this embodiment, the four head units 35 eject ink of different colors (for example, cyan, magenta, yellow, and black) to record a single-color image on the surface (upper surface) of the continuous paper 10. Then, a multi-color image is formed on the upper surface of the continuous paper 10 by superimposing the four single-color images.

[0024] In the following description and drawings, when it is necessary to distinguish between the inks of each color ejected from the four head units 35, cyan ink will be referred to as the "first ink," and the head unit 35 ejecting the first ink will be referred to as the "first head unit 35a." Furthermore, magenta ink will be referred to as the "second ink," and the head unit 35 ejecting the second ink will be referred to as the "second head unit 35b." Furthermore, yellow ink will be referred to as the "third ink," and the head unit 35 ejecting the third ink will be referred to as the "third head unit 35c." Furthermore, black ink will be referred to as the "fourth ink," and the head unit 35 ejecting the fourth ink will be referred to as the "fourth head unit 35d." However, the colors of ink ejected by each of the head units 35a to 35d are not limited to these. Furthermore, the printing unit 3 may be equipped with ejection heads that eject inks of special colors such as orange, blue, and violet in addition to the colors cyan, magenta, yellow, and black.

[0025] Furthermore, the ink supply unit 36 ​​connected to the "first head unit 35a" will be referred to as the "first ink supply unit 36a." Furthermore, the ink supply unit 36 ​​connected to the "second head unit 35b" will be referred to as the "second ink supply unit 36b." Furthermore, the ink supply unit 36 ​​connected to the "third head unit 35c" will be referred to as the "third ink supply unit 36c." Furthermore, the ink supply unit 36 ​​connected to the "fourth head unit 35d" will be referred to as the "fourth ink supply unit 36d." Detailed configurations of these will be described later.

[0026] Fig. 2 is a perspective view that schematically shows the configuration of one head unit 35. However, Fig. 2 does not show a guided portion 176 that is attached to a support base 175, which will be described later. As shown in Fig. 2, each head unit 35 has a plurality of (five in this embodiment) ejection heads 811, a cap 812, a main movement mechanism 813, a head holding plate 814, and a sub-movement mechanism 815.

[0027] First, the configuration of the ejection head 811 will be described. Fig. 3 is a conceptual diagram showing the configuration of the multiple (five in this embodiment) ejection heads 811 and ink supply unit 36 ​​that one head unit 35 has. Fig. 4 is a bottom view of the five ejection heads 811 and head holding plate 814 viewed from below. Note that the five ejection heads 811 have the same configuration. For this reason, Fig. 3 shows only one of the five ejection heads 811 in detail, and the remaining four ejection heads 811 are shown in simplified form.

[0028] As shown in FIG. 3 , each of the five ejection heads 811 has a housing 101, an internal tank 102, and multiple nozzles 103. The housing 101 forms the outer frame of the ejection head 811. The internal tank 102 is disposed inside the housing 101 and is capable of temporarily storing the corresponding ink. The multiple nozzles 103 are arranged at equal intervals in the transport direction and width direction of the continuous paper 10 at the bottom of the housing 101. Each of the multiple nozzles 103 faces the upper surface of the continuous paper 10 being transported below. Each of the multiple nozzles 103 is in communication with the internal tank 102. Each of the multiple nozzles 103 has multiple piezoelectric elements 104 as pressure generating elements, ink chambers 105, and ejection ports 151. The ink chambers 105 are in communication with the internal tank 102.

[0029] When ink is ejected, the ink flows down from the internal tank 102 to the ink chamber 105. Then, by controlling the piezoelectric element 104, the ink in the ink chamber 105 is pressurized, causing the ink to be ejected as droplets from the ejection port 151. That is, the ejection head 811 has an ink ejection surface 161 (lower surface) on which the ejection port 151 that ejects ink while facing downward is formed. However, the nozzle 103 may be of a so-called thermal type, in which the ink in the ink chamber 105 is heated to generate bubbles, thereby pressurizing the ink.

[0030] 2 and 4, the five ejection heads 811 are arranged in a zigzag pattern (staggered pattern) on the upper surface of a head holding plate 814. The head holding plate 814 is a rectangular, plate-like member that extends substantially horizontally. Hereinafter, the longitudinal direction of the head holding plate 814 will be referred to as the "X direction," the lateral direction of the head holding plate 814 as the "Y direction," and the direction perpendicular to the head holding plate 814 as the "Z direction."

[0031] The head holding plate 814 has five through holes 120. Each of the five through holes 120 penetrates the head holding plate 814 in the Z direction. When the head holding plate 814 is viewed from below in the Z direction with each ejection head 811 installed on the upper surface of the head holding plate 814, each through hole 120 surrounds the multiple nozzles 103 of one ejection head 811 and is slightly smaller than the ink ejection surface 161 of one ejection head 811. Therefore, the multiple ejection ports 151 of each ejection head 811 are exposed on the lower surface of the head holding plate 814 through the through holes 120. As a result, ink can be ejected from each ejection head 811 through the through holes 120 of the head holding plate 814 onto the continuous paper 10 being transported below.

[0032] The cap 812 is a member having a larger area than the five ejection heads 811 and the head holding plate 814 when viewed in the Z direction. The cap 812 is used, for example, to cover the nozzles 103 from below while printing is stopped, isolating and sealing the ink ejection surface 161 from the external atmosphere to prevent drying. In other words, the cap 812 can cap the ink ejection surface 161 including the multiple ejection ports 151. As described above, the state in which the nozzles 103 of the five ejection heads 811 are isolated from the external atmosphere and sealed by the cap 812 is referred to as the "capped state." Also, as shown in FIG. 2, the cap 812 has a roughly rectangular box shape and a concave shape that is concave downward. As a result, the cap 812 faces the five ejection heads 811 in the vertical direction and can also receive ink ejected (falling) from the five ejection heads 811 when purging is performed. That is, the cap 812 can receive ink dropping from the ejection ports 151 when it is at the facing position P1 (see FIG. 2) facing the ink ejection surface 161 of the ejection head 811 from below.

[0033] The main movement mechanism 813 has a pair of linear guides 171, 172, a ball screw 173, and a cap motor 174. The pair of linear guides 171, 172, the ball screw 173, and the cap motor 174 are arranged on a substantially horizontal upper surface of a support base 175 having a substantially rectangular parallelepiped shape. Also, as shown in FIG. 2, the pair of linear guides 171, 172 are each arranged along the X direction.

[0034] The ball screw 173 extends in the X direction and is disposed between a pair of linear guides 171 and 172. The ball screw 173 is connected to a cap motor 174 and rotates when driven by the cap motor 174. The cap 812 is connected to the ball screw 173 via a connecting member (not shown). The rotation of the ball screw 173 causes the cap 812 to move in the X direction along the pair of linear guides 171 and 172. This allows the main movement mechanism 813 to move the cap 812 in the X direction between a facing position P1 where the cap 812 faces the ink ejection surfaces 161 of the five ejection heads 811 from below, and a retracted position P2 spaced apart from the facing position P1. As a result, the main movement mechanism 813 can move the cap 812 so that the cap 812 faces the ink ejection surfaces 161 of the five ejection heads 811 from below, or so that the cap 812 does not face the ink ejection surfaces 161 from below.

[0035] The sub-movement mechanism 815 is a mechanism that raises and lowers the head holding plate 814, on which each ejection head 811 is placed, by several centimeters to several tens of centimeters up and down (in the Z direction). With the caps 812 positioned at the opposing position P1, the sub-movement mechanism 815 lowers the head holding plate 814, causing the head holding plate 814 to come into contact with the caps 812. This brings the ink ejection surfaces 161 of each ejection head 811 into a sealed state (capped state). Furthermore, by raising the head holding plate 814 with the sub-movement mechanism 815, the ink ejection surfaces 161 of each ejection head 811 are released from the sealed state by the caps 812.

[0036] As described above, the "decapped state" refers to a state in which the nozzles 103 of the five ejection heads 811 are isolated and sealed from the external atmosphere by the caps 812 and released. That is, the sub-movement mechanism 815 is switchable between the "capped state" in which the ink ejection surfaces 161 are isolated from the external atmosphere by the caps 812 and the "decapped state" in which the "capped state" is released. The specific structure of the sub-movement mechanism 815 will be described below. As shown in FIG. 2, the sub-movement mechanism 815 has a support plate 851, a head motor 852, a ball screw 853, a pair of linear guides (not shown), and a screw member 854.

[0037] The support plate 851 has a substantially rectangular parallelepiped shape, is fixed to the upper surface of the support base 175, and extends like a plate in a substantially vertical direction. A head motor 852 is fixed to the support plate 851, and a ball screw 853 is fixed to the rotation shaft of the head motor 852. The ball screw 853 extends in the Z direction and is disposed between a pair of linear guides (not shown) that also extend in the Z direction. The screw member 854 is fixed to the head holding plate 814 on which the five ejection heads 811 are disposed. The screw member 854 has a through hole with a female thread formed around its periphery. The ball screw 853 is inserted into the through hole and is screwed into the female thread.

[0038] When the ball screw 853 is rotated by driving the head motor 852, a threaded member 854 that threads onto the ball screw 853 and a head holding plate 814 to which the threaded member 854 is fixed move in the Z direction along a pair of linear guides. This allows the sub-movement mechanism 815 to simultaneously raise and lower the five ejection heads 811 arranged on the head holding plate 814 up and down. As a result, the sub-movement mechanism 815 can bring the ink ejection surfaces 161 of the five ejection heads 811 close to the caps 812 to set them in a "capped state," or move them away from the caps 812 to set them in a "decapped state."

[0039] Next, the configuration of the first slider 41a to the fourth slider 41d will be described. FIG. 5 is a conceptual diagram showing the positional relationship between the first head unit 35a to the fourth head unit 35d of the inkjet printing device 1 and the device housing 4. As shown in FIG. 5, when the inkjet printing device 1 is driven, the first head unit 35a to the fourth head unit 35d are arranged side by side in the internal space of the device housing 4. In addition, a control unit 9 and an input unit 11 are provided near a wall of the device housing 4 that is perpendicular to the arrangement of the first maintenance position Poa to the fourth maintenance position Pod, which will be described later. In addition, the first head unit 35a to the fourth head unit 35d are each movable between the internal space of the device housing 4 and the external space.

[0040] 5, a first slider 41a is provided that supports the first head unit 35a so that it can slide between a first drive position Pia in the internal space of the device housing 4 and a first maintenance position Poa in the external space of the device housing 4. In addition to the first slider 41a, a second slider 41b is provided that supports the second head unit 35b so that it can slide between a second drive position Pib in the internal space of the device housing 4 and a second maintenance position Pob in the external space of the device housing 4. In addition to the first slider 41a and the second slider 41b, a third slider 41c is provided that supports the third head unit 35c so that it can slide between a third drive position Pic in the internal space of the device housing 4 and a third maintenance position Poc in the external space of the device housing 4. In addition to the first slider 41a to the third slider 41c, a fourth slider 41d is provided to support the fourth head unit 35d so that it can slide between a fourth drive position Pid located in the internal space of the device housing 4 and a fourth maintenance position Pod located in the external space of the device housing 4.

[0041] The first slider 41a, the second slider 41b, the third slider 41c, and the fourth slider 41d have the same configuration. Therefore, the following description will be given taking the configuration of the first slider 41a and the second slider 41b as an example. Figure 6 is a side view schematically showing the configuration of the first head unit 35a and the first slider 41a. Figure 7 is a side view schematically showing the configuration of the second head unit 35b and the second slider 41b.

[0042] As shown in FIG. 6, the first slider 41a is a guide rail that extends from a first drive position Pia in the internal space of the device housing 4 to a first maintenance position Poa in the external space of the device housing 4. The first slider 41a has a pair of first rail members 40a, each extending in the X direction. When the first support base 175a, which is the support base 175 described above, is placed on the first slider 41a, a pair of first guided portions 176a provided on the underside of the first support base 175a are engaged with the first rail member 40a so as to be slidable in the X direction. As a result, the first support base 175a and the first head unit 35a held by the first support base 175a are guided in the X direction along the first slider 41a. As a result, the worker can pull out the first support stand 175a and the first head unit 35a held by the first support stand 175a from the first drive position Pia inside the device housing 4 to the first maintenance position Poa outside the device housing 4, and then push them back to the first drive position Pia.

[0043] A first detection unit 45a, which may be a photomicrosensor, is fixed to the first slider 41a. A sensor dog (not shown) for position detection is fixed to the first support base 175a. The first detection unit 45a outputs a detection signal each time it detects a sensor dog passing nearby as the first support base 175a moves in the X direction. Hereinafter, the detection signal output from the first detection unit 45a will be referred to as the "first detection signal." That is, the first detection unit 45a detects that the first head unit 35a, supported by the first support base 175a, has moved between the first drive position Pia and the first maintenance position Poa, and outputs the first detection signal. This allows the control unit 9, described later, to determine the position of the first head unit 35a by referring to the first detection signal output from the first detection unit 45a.

[0044] As shown in FIG. 7, the second slider 41b is a guide rail that extends from a second drive position Pib in the internal space of the device housing 4 to a second maintenance position Pob in the external space of the device housing 4. The second slider 41b has a pair of second rail members 40b, each extending in the X direction. When the second support base 175b, which is the support base 175, is placed on the second slider 41b, a pair of second guided portions 176b provided on the underside of the second support base 175b are engaged with the second rail member 40b so as to be slidable in the X direction. As a result, the second support base 175b and the second head unit 35b held by the second support base 175b are guided in the X direction along the second slider 41b. As a result, the worker can pull out the second support stand 175b and the second head unit 35b held by the second support stand 175b from the second drive position Pib inside the device housing 4 to the second maintenance position Pob outside the device housing 4, and then push them back to the second drive position Pib.

[0045] A second detection unit 45b, which may be a photomicrosensor, is fixed to the second slider 41b. A sensor dog (not shown) for position detection is fixed to the second support base 175b. The second detection unit 45b outputs a detection signal each time it detects a sensor dog passing nearby as the second support base 175b moves in the X direction. Hereinafter, the detection signal output from the second detection unit 45b will be referred to as the "second detection signal." That is, the second detection unit 45b detects that the second head unit 35b, supported by the second support base 175b, has moved between the second drive position Pib and the second maintenance position Pob, and outputs the second detection signal. This allows the control unit 9, described later, to determine the position of the second head unit 35b by referring to the second detection signal output from the second detection unit 45b.

[0046] Similarly, a third detector 45c is fixed to the third slider 41c. The third detector 45c detects that the third head unit 35c, while supported by the support base 175, has moved between the third drive position Pic and the third maintenance position Poc, and outputs a third detection signal. Similarly, a fourth detector 45d is fixed to the fourth slider 41d. The fourth detector 45d detects that the fourth head unit 35d, while supported by the support base 175, has moved between the fourth drive position Pid and the fourth maintenance position Pod, and outputs a fourth detection signal.

[0047] Next, a detailed configuration of the ink supply unit 36 ​​will be described. The ink supply unit 36 ​​is a device for circulating a portion of the ink while supplying ink to the head unit 35. As shown in Fig. 3, the ink supply unit 36 ​​has a supply tank 51, a recovery tank 52, a supply-side manifold 61, a plurality (five in this embodiment) of supply-side thin pipes 62, a plurality (five in this embodiment) of recovery-side thin pipes 63, a recovery-side manifold 64, a return pipe 65, a circulation pump 71, a plurality (five in this embodiment) of supply-side on-off valves 73, a plurality (five in this embodiment) of head outlet-side on-off valves 74, a heater 76, a filter 87, and a degassing unit 88.

[0048] The supply tank 51 is a container for temporarily storing ink to be supplied to the ejection head 811. Inside the supply tank 51, an internal chamber 510 capable of temporarily storing ink is provided.

[0049] The supply-side manifold 61 and the five supply-side thin pipes 62 are pipes that connect the supply tank 51 and the five ejection heads 811 of one head unit 35. The supply-side manifold 61 is a thick pipe whose upstream end is connected to communicate with the internal chamber 510 of the supply tank 51. The five supply-side thin pipes 62 are thin pipes that branch off from the supply-side manifold 61. The upstream end of each of the five supply-side thin pipes 62 is connected to communicate with the internal passage of the supply-side manifold 61, and the downstream end is connected to communicate with the internal tank 102 of one ejection head 811.

[0050] Furthermore, in this embodiment, a supply-side on-off valve 73 is interposed in each supply-side thin pipe 62. For example, a solenoid valve that opens and closes under the control of the control unit 9 is used as the supply-side on-off valve 73. However, a manually opened and closed on-off valve may also be used as the supply-side on-off valve 73. When the supply-side on-off valve 73 is closed, communication between the internal passages of the supply-side thin pipes 62 is blocked. That is, when the supply-side on-off valve 73 is closed, the flow of ink from the supply tank 51 to the ejection head 811 is blocked. On the other hand, when the supply-side on-off valve 73 is open, communication between the internal passages of the supply-side thin pipes 62 is permitted. However, the supply-side on-off valve 73 is not necessarily provided.

[0051] The five recovery side thin pipes 63 and the recovery side manifold 64 are pipes that connect the five ejection heads 811 of the head unit 35 to the recovery tank 52. Each of the five recovery side thin pipes 63 is a thin tube that branches off from the recovery side manifold 64. The upstream end of each of the five recovery side thin pipes 63 is connected to communicate with the internal tank 102 of one of the ejection heads 811, and the downstream end is connected to communicate with an internal passage of the recovery side manifold 64. The recovery side manifold 64 is a thick pipe that is connected to communicate with an internal chamber 520 (described later) of the recovery tank 52 at its downstream end.

[0052] Furthermore, in this embodiment, a head outlet-side on-off valve 74 is interposed in each recovery-side thin pipe 63. For example, a solenoid valve that opens and closes under the control of the control unit 9 is used as the head outlet-side on-off valve 74. However, a manually opened and closed on-off valve may also be used as the head outlet-side on-off valve 74. When the head outlet-side on-off valve 74 is closed, communication between the internal passages of the recovery-side thin pipes 63 is blocked. In other words, when the head outlet-side on-off valve 74 is closed, the flow of ink from the ejection head 811 to the recovery tank 52 is blocked. On the other hand, when the head outlet-side on-off valve 74 is open, communication between the internal passages of the recovery-side thin pipes 63 is permitted. However, the head outlet-side on-off valve 74 is not necessarily provided.

[0053] The recovery tank 52 is a container for temporarily storing the ink recovered from the ejection head 811. Inside the recovery tank 52, an internal chamber 520 capable of temporarily storing the ink is provided.

[0054] 3, a pressurizing mechanism 515 is connected to the supply tank 51. The pressurizing mechanism 515 pressurizes the inside of the supply tank 51 and adjusts the air pressure in the internal chamber 510 of the supply tank 51 to a positive pressure (pressure higher than atmospheric pressure). The pressurizing mechanism 515 is composed of, for example, a compressor, a pressurized buffer tank, a pressure adjustment mechanism (regulator), etc. Furthermore, a depressurizing mechanism 524 is connected to the recovery tank 52. The depressurizing mechanism 524 depressurizes the inside of the recovery tank 52 and adjusts the air pressure in the internal chamber 520 of the recovery tank 52 to a negative pressure (pressure lower than atmospheric pressure). The depressurizing mechanism 524 is composed of, for example, a vacuum pump, a depressurized buffer tank, a pressure adjustment mechanism (regulator), etc.

[0055] The operations of the pressurizing mechanism 515 and the decompression mechanism 524 are configured to be controllable by the control unit 9. When the pressurizing mechanism 515 and the decompression mechanism 524 are driven, a pressure difference is created between the internal chamber 510 of the supply tank 51 and the internal chamber 520 of the recovery tank 52. This allows the ink stored in the supply tank 51 to be supplied to each ejection head 811, and further allows the ink remaining in each ejection head 811 (ink that was not ejected from each ejection head 811) to be recovered in the recovery tank 52.

[0056] The return pipe 65 is a pipe that connects the internal chamber 520 of the recovery tank 52 and the internal chamber 510 of the supply tank 51 so that they can communicate with each other. That is, the return pipe 65 connects the recovery tank 52 and the supply tank 51. As shown in FIG. 3 , the upstream end of the internal passage of the return pipe 65 is connected in communication with the internal chamber 520 of the recovery tank 52. In addition, the downstream end of the internal passage of the return pipe 65 is connected in communication with the internal chamber 510 of the supply tank 51.

[0057] With the above configuration, an ink circulation path 55 is formed, which runs from the supply tank 51 through the supply manifold 61, the supply thin pipe 62, the internal tank 102 of the ejection head 811, the recovery thin pipe 63, the recovery manifold 64, the recovery tank 52, and the return pipe 65, and then returns to the supply tank 51. That is, the circulation path 55 includes the supply tank 51, the ejection head 811, the recovery tank 52, and the return pipe 65. In addition, a circulation pump 71, a heater 76, a filter 87, and a degassing unit 88 are inserted in the return pipe 65.

[0058] The circulation pump 71 is a device that performs a liquid transfer operation to transfer ink from the recovery tank 52 to the supply tank 51 via the return pipe 65. The circulation pump 71 is electrically connected to the control unit 9. In accordance with an operation signal from the control unit 9, the circulation pump 71 generates a flow of ink in the internal passage of the return pipe 65 from the recovery tank 52 to the supply tank 51.

[0059] The heater 76 is a device that heats the ink being transported in the internal passage of the return pipe 65. The heater 76 heats the ink flowing from the recovery tank 52 to the supply tank 51. The heater 76 is located in the return pipe 65 between the circulation pump 71 and the supply tank 51. The heater 76 is electrically connected to the control unit 9.

[0060] The filter 87 is inserted in the return pipe 65 downstream of the heater 76 in the ink sending direction and upstream of the supply tank 51 in the ink sending direction. The filter 87 filters the ink sent through the internal passage of the return pipe 65 and removes foreign matter contained in the ink.

[0061] The degassing unit 88 is inserted in the return pipe 65 downstream of the filter 87 in the ink sending direction and upstream of the supply tank 51 in the ink sending direction. The degassing unit 88 in this embodiment is a so-called hollow fiber membrane degassing module. The degassing unit 88 removes air bubbles from the ink being sent through the internal passage of the return pipe 65.

[0062] Next, the control unit 9 will be described. The control unit 9 is an information processing device for controlling each part of the inkjet printing apparatus 1. FIG. 8 is a block diagram showing the connection between the control unit 9 and each part of the inkjet printing apparatus 1. As conceptually shown in FIG. 8, the control unit 9 has a processor 91 such as a CPU, a memory 92 such as RAM, and a storage unit 93 such as a hard disk drive. The storage unit 93 stores a computer program 9P for transporting and printing on the continuous paper 10, circulating ink, and performing maintenance on the first head unit 35a to the fourth head unit 35d.

[0063] 8, the control unit 9 is electrically and communicatively connected to the transport unit 2, the ejection heads 811 of the four head units 35a to 35d of the printing unit 3, the main movement mechanism 813, the sub-movement mechanism 815, the circulation pumps 71, the five supply-side on-off valves 73, the five head outlet-side on-off valves 74, the heater 76, the pressurization mechanism 515, the decompression mechanism 524 of the four ink supply units 36a to 36d of the printing unit 3, the four sliders 41a to 41d, and the four detection units 45a to 45d. The control unit 9 controls the operation of each of these units in accordance with a computer program 9P.

[0064] 8, the control unit 9 is electrically and communicatively connected to the input unit 11. The input unit 11 is a device capable of receiving commands to transition the multiple head units 35 to a maintenance mode. More specifically, the input unit 11 is a device capable of receiving a first command to move the cap 812 of the first head unit 35a from the facing position P1 to the retracted position P2, and / or a second command to move the cap 812 of the second head unit 35b from the facing position P1 to the retracted position P2, and / or a third command to move the cap 812 of the third head unit 35c from the facing position P1 to the retracted position P2, and / or a fourth command to move the cap 812 of the fourth head unit 35d from the facing position P1 to the retracted position P2.

[0065] The first command includes a command to drive the sub-movement mechanism 815 of the first head unit 35a to switch the ink ejection surfaces 161 of the five ejection heads 811 from the "capped state" to the "decapped state." The second command includes a command to drive the sub-movement mechanism 815 of the second head unit 35b to switch the ink ejection surfaces 161 of the five ejection heads 811 from the "capped state" to the "decapped state." The third command includes a command to drive the sub-movement mechanism 815 of the third head unit 35c to switch the ink ejection surfaces 161 of the five ejection heads 811 from the "capped state" to the "decapped state." The fourth command includes a command to drive the sub-movement mechanism 815 of the fourth head unit 35d to switch the ink ejection surfaces 161 of the five ejection heads 811 from the "capped state" to the "decapped state."

[0066] The input unit 11 includes an input interface such as a touch panel. An operator inputs the first to fourth commands described above for transitioning the first to fourth head units 35a to 35d to the maintenance mode individually to the input unit 11 via the input interface. When the input unit 11 receives the first command, it outputs a first input signal related to the first command to the control unit 9. When the input unit 11 receives a second command, it outputs a second input signal related to the second command to the control unit 9. When the input unit 11 receives a third command, it outputs a third input signal related to the third command to the control unit 9. When the input unit 11 receives a fourth command, it outputs a fourth input signal related to the fourth command to the control unit 9. However, the input unit 11 may be configured integrally with the control unit 9 and other units.

[0067] <2. Procedures for continuous paper transport, printing, ink circulation, and head unit maintenance> Next, the procedures for transporting the continuous paper 10, printing on the continuous paper 10, circulating ink, and maintaining the first head unit 35a to the fourth head unit 35d performed in the inkjet printing device 1 will be described.

[0068] First, when transporting the continuous paper 10, printing on the continuous paper 10, and circulating the ink, the control unit 9 operates the transport unit 2 to transport the continuous paper 10 in the longitudinal direction along a predetermined transport path. Then, while transporting the continuous paper 10, the control unit 9 controls the multiple nozzles 103 of each of the four head units 35 (first head unit 35a to fourth head unit 35d) to eject droplets of the first to fourth inks onto the surface of the continuous paper 10. In this way, a multicolor image is recorded on the surface of the continuous paper 10.

[0069] Here, as preparations for transporting the continuous paper 10, printing the continuous paper 10, and circulating the ink, a sufficient amount of ink is stored in the internal chamber 510 of each supply tank 51 of the four ink supply units 36 (first ink supply unit 36a to fourth ink supply unit 36d). The control unit 9 also opens the five supply-side on-off valves 73 and five head-outlet-side on-off valves 74 of each ink supply unit 36. The control unit 9 then drives the circulation pump 71, heater 76, pressurizing mechanism 515, and decompression mechanism 524 of each of the four ink supply units 36 (first ink supply unit 36a to fourth ink supply unit 36d). Specifically, the control unit 9 drives the circulation pump 71 to circulate the ink in the ink circulation path 55, while driving the pressurizing mechanism 515 and decompression mechanism 524 to supply the first to fourth inks to the internal tanks 102 of the corresponding ejection heads 811.

[0070] Next, the procedure for performing maintenance on the first head unit 35a to the fourth head unit 35d will be described. FIG. 9 is a flowchart showing the procedure for performing maintenance on the first head unit 35a to the fourth head unit 35d. At the start of the maintenance shown in FIG. 9, the inkjet printing device 1 is assumed to be in a standby state. That is, transport of the continuous paper 10 is stopped, and the first head unit 35a to the fourth head unit 35d have each stopped ejecting ink droplets onto the continuous paper 10. Furthermore, the caps 812 of each of the first head unit 35a to the fourth head unit 35d are positioned at the facing position P1. The five ejection heads 811 of each of the first head unit 35a to the fourth head unit 35d are lowered by the drive of the sub-movement mechanism 815. As a result, the ink ejection surface 161 of each ejection head 811 is isolated and sealed from the external atmosphere by the caps 812, and is in a "capped state."

[0071] When the inkjet printing apparatus 1 is in the standby state described above, maintenance of the first head unit 35a to the fourth head unit 35d is started. The worker inputs commands (the above-described first command, second command, third command, and / or fourth command) to transition any / all of the first head unit 35a to the fourth head unit 35d to maintenance mode via the input interface of the input unit 11 (step S1). The following example assumes that the worker has input a command (the first command and the second command) to perform maintenance on the first head unit 35a and the second head unit 35b.

[0072] In this case, when the input unit 11 receives a first command, it outputs a first input signal to the control unit 9. Furthermore, when the input unit 11 receives a second command, it outputs a second input signal to the control unit 9. As a result, the first input signal and the second input signal from the input unit 11 are input to the control unit 9. However, at this stage, the control unit 9 does not control the driving of the main movement mechanism 813 and the sub-movement mechanism 815 of the first head unit 35a and the second head unit 35b, respectively.

[0073] Next, the worker pulls out any of the first head unit 35a to the fourth head unit 35d to the space outside the device housing 4 to perform maintenance (step S2). For example, the worker first pulls out the first support base 175a and the first head unit 35a, which are arranged on the first slider 41a, from the first drive position Pia inside the device housing 4 to the first maintenance position Poa outside the device housing 4. Then, the first detector 45a detects that the first head unit 35a has moved between the first drive position Pia and the first maintenance position Poa, and outputs a first detection signal. As a result, the control unit 9 can determine that the first head unit 35a has moved from the first drive position Pia to the first maintenance position Poa by referring to the first detection signal output from the first detector 45a.

[0074] When the control unit 9 detects that the first head unit 35a has moved from the first drive position Pia to the first maintenance position Poa, it stops driving the circulation pump 71 of the first ink supply unit 36a. By stopping the circulation of the first ink, it is possible to prevent ink leakage and air intake from the ejection ports 151 of the ejection heads 811 of the first head unit 35a, even if the first head unit 35a is pulled out to the outside of the device housing 4. This suppresses pressure changes on the ejection heads 811, preventing damage to the ejection heads 811. The control unit 9 also closes the supply-side opening / closing valve 73 and the head outlet-side opening / closing valve 74 of the first ink supply unit 36a. This further prevents ink leakage and air intake from the ejection ports 151 of the ejection heads 811 of the first head unit 35a.

[0075] Next, the control unit 9 checks whether the head unit 35 that has been pulled out into the space outside the device housing 4 was originally input to the input unit 11 in step S1 as a target for maintenance (step S3). In this embodiment, it checks whether the first head unit 35a that has moved to the first maintenance position Poa outside the device housing 4 was input to the input unit 11 as a target for maintenance. As described above, since the first head unit 35a was input to the input unit 11 in step S1 as a target for maintenance (step S3: Yes), the control unit 9 drives the main movement mechanism 813 and sub-movement mechanism 815 of the first head unit 35a after a certain time lag. More specifically, the control unit 9 drives the sub-movement mechanism 815 of the first head unit 35a to switch the ink ejection surfaces 161 of the ejection heads 811 of the first head unit 35a to the "decapped state" (step S4). This allows the worker to check the condition of the ink ejection surface 161 of each ejection head 811 and perform some maintenance. Thereafter, the control unit 9 drives the main movement mechanism 813 to move the cap 812 of the first head unit 35a away from the facing position P1 to the retracted position P2, completely exposing the ink ejection surface 161 of each ejection head 811 (step S5). This allows the worker to have complete access to the ink ejection surface 161, making it easy to clean the areas near the nozzles 103 and replace parts.

[0076] Next, when the worker completes maintenance such as cleaning the ejection heads 811 and replacing parts, the worker pushes back the first support base 175a and the first head unit 35a, which are arranged on the first slider 41a, from the first maintenance position Poa outside the device housing 4 to the first drive position Pia inside the device housing 4. The first detector 45a then detects that the first head unit 35a has moved between the first maintenance position Poa and the first drive position Pia, and outputs a first detection signal. By referencing the first detection signal output from the first detector 45a, the control unit 9 can determine that the first head unit 35a has moved from the first maintenance position Poa to the first drive position Pia. When the control unit 9 detects that the first head unit 35a has moved from the first maintenance position Poa to the first drive position Pia (step S6: YES), it again drives the main movement mechanism 813 of the first head unit 35a. As a result, the control unit 9 moves the caps 812 from the retracted position P2 to the facing position P1, so that they face each of the ejection heads 811 (step S7). The control unit 9 also drives the sub-movement mechanism 815 of the first head unit 35a again. As a result, the head holding plate 814 and the five ejection heads 811 of the first head unit 35a are lowered, and the ink ejection surfaces 161 of each of the ejection heads 811 are again switched to the "capped state" in which they are isolated and sealed from the external atmosphere by the caps 812 (step S8).

[0077] As described above, the control unit 9 can pull each of the first through fourth head units 35a through 35d out of the device housing 4, perform maintenance such as cleaning and component replacement, and push the head units back into the internal space of the device housing 4. Furthermore, commands for moving the caps 812 of each of the head units 35a through 35d to the retracted position P2 and switching each of the head units 35a through 35d to the "decapped state" can be input all at once via the input unit 11, thereby reducing the burden on the operator. Furthermore, the ink ejection surfaces 161 of the five ejection heads 811 of the head units 35a through 35d undergoing maintenance are switched to the "decapped state" immediately before maintenance is actually performed on each of the head units 35a through 35d. This further reduces the time that the ink ejection surfaces 161 of the head units 35a through 35d undergoing maintenance are exposed to the external atmosphere. This prevents the nozzles 103 formed on the ink ejection surfaces 161 from drying out. Furthermore, the ink ejection surfaces 161 of the head units 35 not undergoing maintenance (in this embodiment, the third head unit 35c and the fourth head unit 35d) remain in a "capped state" even while maintenance is being performed on the other head units 35 (in this embodiment, the first head unit 35a and the second head unit 35b), thereby preventing the nozzles 103 formed on the ink ejection surfaces 161 of these head units 35 not undergoing maintenance from drying out.

[0078] That is, the control unit 9 of this embodiment performs the following steps: a) when a first input signal is input from the input unit 11 and the control unit 9 detects that the first head unit 35a has moved from the first drive position Pia to the first maintenance position Poa based on a first detection signal input from the first detection unit 45a, after a first predetermined time has elapsed, the control unit 9 controls the sub-movement mechanism 815 (first movement mechanism) of the first head unit 35a to switch the ink ejection surface 161 of the first head unit 35a from the "capped state" to the "decapped state." and b) when a second input signal is input from the input unit 11 and it is detected that the second head unit 35b has moved from the second drive position Pib to the second maintenance position Pob based on the second detection signal input from the second detection unit 45b, after a second predetermined time has elapsed, the sub-movement mechanism 815 (second movement mechanism) of the second head unit 35b is controlled to switch the ink ejection surface 161 of the second head unit 35b from the "capped state" to the "decapped state".

[0079] Furthermore, as described above, when the control unit 9 detects that any of the head units 35 has moved from the drive position inside the device housing 4 to the maintenance position outside the device housing 4, it stops driving the circulation pump 71 of the ink supply unit 36 ​​corresponding to the moved head unit 35. This stops the circulation of ink in the ink supply unit 36 ​​corresponding to the head unit 35 that has moved to the maintenance position, so that even if the head unit 35 is pulled out to the outside of the device housing 4, it is possible to prevent ink leakage and air intake from the ejection ports 151 of the ejection head 811 of the pulled-out head unit 35. This suppresses changes in pressure applied to the ejection head 811 and prevents damage to the ejection head 811. Furthermore, for the ink supply unit 36 ​​corresponding to the head unit 35 that is not undergoing maintenance (in this embodiment, the third head unit 35c and the fourth head unit 35d), the circulation of ink continues in the corresponding ink supply unit 36 ​​even while maintenance is being performed on the other head units 35 (in this embodiment, the first head unit 35a and the second head unit 35b). Therefore, it is possible to further prevent the outlets 151 of the ejection heads 811 of the head units 35 that are not undergoing maintenance from drying out.

[0080] That is, when the control unit 9 of this embodiment detects that the first head unit 35a has moved from the first drive position Pia to the first maintenance position Poa, it stops driving the circulation pump 71 (first circulation pump) of the first ink supply unit 36a. Furthermore, when the control unit 9 of this embodiment detects that the second head unit 35b has moved from the second drive position Pib to the second maintenance position Pob, it stops driving the circulation pump 71 (second circulation pump) of the second ink supply unit 36b. In this way, in this embodiment, because the circulation of ink is stopped immediately before maintenance is performed on each of the head units 35a and 35b, it is possible to further prevent the ejection ports 151 from drying out.

[0081] Furthermore, as described above, when the worker completes maintenance such as cleaning or part replacement of any of the head units 35a to 35d, they push that head unit 35a to 35d back from the maintenance positions Poa to Pod outside the device housing 4 to the drive positions Pia to Pid inside the device housing 4. Then, when the control unit 9 detects, based on the first to fourth detection signals, that one of the head units 35a to 35d has moved from the maintenance positions Poa to Pod to the drive positions Pia to Pid, ​​it drives the main movement mechanism 813 and the sub-movement mechanism 815 of that head unit 35a to 35d again. As a result, the control unit 9 moves the cap 812 of that head unit 35a to 35d from the retracted position P2 to the facing position P1. Furthermore, the control unit 9 brings the ink ejection surface 161 of the ejection head 811 of that head unit 35a to 35d into contact with the corresponding cap 812 again. As a result, immediately after maintenance of the head units 35a to 35d is completed, the ink ejection surfaces 161 are switched back to the "capped state" by the caps 812, further shortening the time that the ink ejection surfaces 161 of the head units 35a to 35d for which maintenance has been performed are exposed to the external atmosphere. This further reduces the drying of the ink ejection surfaces 161 and the nozzles 103 formed on the ink ejection surfaces 161.

[0082] That is, after the above step a), when the control unit 9 detects, based on the first detection signal input from the first detection unit 45a, that the first head unit 35a has moved from the first maintenance position Poa to the first drive position Pia, the control unit 9 controls the sub-movement mechanism 815 (first movement mechanism) of the first head unit 35a to cap the ink ejection surface 161 (first ink ejection surface) of each ejection head 811 of the first head unit 35a with the corresponding cap 812 (first cap). Furthermore, after the above step b), when the control unit 9 detects, based on the second detection signal input from the second detection unit 45b, that the second head unit 35b has moved from the second maintenance position Pob to the second drive position Pib, the control unit 9 controls the sub-movement mechanism 815 (second movement mechanism) of the second head unit 35b to cap the ink ejection surface 161 (second ink ejection surface) of each ejection head 811 of the second head unit 35b with the corresponding cap 812 (second cap).

[0083] Furthermore, as described above, in step S3, the control unit 9 checks whether the head unit 35 that has been pulled out into the external space of the device housing 4 was originally input to the input unit 11 in step S1 as a target for maintenance. Then, the control unit 9 opens and closes the cap 812 only if the result is "step S3: Yes." This configuration allows the worker to proceed with the maintenance work while checking whether it is going according to the original plan. As a result, the work can be performed more accurately.

[0084] Here, it is assumed that in step S1, there is no plan to perform maintenance on the first head unit 35a, and the worker has not input a first command to the input unit 11. Then, in step S3, if it is confirmed that the first head unit 35a, which has been pulled out of the device housing 4, has not been input to the input unit 11 as a target for maintenance in the first place (step S3: No), the control unit 9 recognizes that an error has occurred. In this case, the control unit 9 waits without driving the main movement mechanism 813 and sub-movement mechanism 815 of the first head unit 35a, and notifies the user of the error by displaying an error message on a display (not shown) or the like arranged on the input unit 11 or by sounding an alarm (step S9).

[0085] That is, when the control unit 9 of this embodiment detects that the first head unit 35a has moved from the first drive position Pia to the first maintenance position Poa based on the first detection signal input from the first detection unit 45a while the first input signal is not being input from the input unit 11, it recognizes this as an error and waits with the ink ejection surface 161 (first ink ejection surface) of each ejection head 811 of the first head unit 35a in the "capped state" without controlling the main moving mechanism 813 and sub-moving mechanism 815 of the first head unit 35a. Furthermore, when the control unit 9 of this embodiment detects that the second head unit 35b has moved from the second drive position Pib to the second maintenance position Pob based on the second detection signal input from the second detection unit 45b while the second input signal is not being input from the input unit 11, it recognizes this as an error and waits with the ink ejection surfaces 161 (second ink ejection surfaces) of each ejection head 811 of the second head unit 35b in the "capped state" without controlling the main movement mechanism 813 and sub-movement mechanism 815 of the second head unit 35b. With this configuration, if a head unit 35 other than the one that was intended to be pulled out into the external space is pulled out, the worker can recognize this as an error and can suspend further work.

[0086] <3. Modifications> Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0087] In the above embodiment, the sub-movement mechanism 815 of the head unit 35 is driven to raise and lower the head holding plate 814 and each ejection head 811, thereby switching between the "capped state" and the "decapped state" of the ink ejection surface 161 of each ejection head 811. However, instead of raising and lowering each ejection head 811 of the head unit 35, the cap 812 may be raised and lowered to switch between the "capped state" and the "decapped state" of the ink ejection surface 161 of each ejection head 811.

[0088] In the above embodiment, the sub-movement mechanism 815 of the head unit 35 is driven to switch the ink ejection surface 161 of each ejection head 811 between the "capped state" and the "decapped state," and the main movement mechanism 813 is driven to move the cap 812 in the X direction, thereby completely exposing the ink ejection surface 161 of each ejection head 811 from the cap 812. However, if an operator can completely access the ink ejection surface 161 and perform various maintenance tasks simply by changing the distance in the Z direction between the ink ejection surface 161 and the cap 812, the main movement mechanism 813 may be omitted.

[0089] In the above embodiment, the operator uses the input unit 11 to issue commands to drive the sub-movement mechanism 815 of the head unit 35 to switch the ink ejection surface 161 of each ejection head 811 between the "capped state" and the "decapped state" and to move the cap 812 in the "decapped state" between the opposing position P1 and the retracted position P2 in succession. However, it may be possible to issue commands separately to switch the ink ejection surface 161 between the "capped state" and the "decapped state" and to move the cap 812 between the opposing position P1 and the retracted position P2. That is, the operator may use the input unit 11 to issue commands separately to switch the ink ejection surface 161 from the "capped state" to the "decapped state" and to move the cap 812 to the retracted position P2 after decapping.

[0090] Similarly, the operator may be able to individually issue commands via the input unit 11 to move the cap 812 of the head unit 35 from the retracted position P2 to the opposing position P1, and to put the ink ejection surface 161 of each ejection head 811 into a "capped state" with respect to the cap 812 located at the opposing position P1.

[0091] Furthermore, the elements appearing in the above embodiments may be combined as appropriate within the scope of not causing any contradiction. [Explanation of symbols]

[0092] 1. Inkjet printing device 2. Conveyor section 3 Printing Department 4. Device housing 9 Control Unit 10 Continuous Paper 11 Input section 35 Head Unit 35a First head unit 35b Second head unit 35c 3rd head unit 35d 4th head unit 36 Ink supply unit 36a First ink supply unit 36b Second ink supply unit 36c Third ink supply unit 36d Fourth ink supply unit 41a First slider 41b Second slider 41c 3rd slider 41d 4th slider 45a First detection unit 45b Second detection unit 45c Third detection unit 45d Fourth detection unit 51 Supply Tank 52 Recovery Tank 65 Return piping 71 Circulation Pump 103 (Discharge head) nozzle 151 (Discharge head) outlet 161 (ejection head) ink ejection surface 811 Discharge head 812 Cap 813 Main movement mechanism 815 Sub-movement mechanism P1 Opposite position P2 Evacuation position Pia 1st drive position Pib Second drive position Pic 3rd drive position Pid 4th drive position Poa 1st maintenance position Pob 2nd maintenance position Poc 3rd maintenance position Pod 4th maintenance position

Claims

1. An inkjet printing device that prints on a print medium using an inkjet method, A device housing; a first head unit including: a first ejection head having a first ink ejection surface formed with first ejection ports that eject a first ink while facing downward; a first cap that can cap the first ink ejection surface; and a first movement mechanism that can switch between a capped state in which the first ink ejection surface is isolated from an external atmosphere by the first cap and a decapped state in which the capped state is released; a second head unit including a second ejection head having a second ink ejection surface formed with second ejection ports that eject a second ink while facing downward, a second cap that can cap the second ink ejection surface, and a second movement mechanism that can switch between a capped state in which the second ink ejection surface is isolated from an external atmosphere by the second cap and a decapped state in which the capped state is released; a first slider that supports the first head unit so that the first head unit can slide between a first drive position that is in an internal space of the device housing and a first maintenance position that is in an external space of the device housing; a second slider provided separately from the first slider, supporting the second head unit so that the second head unit is slidable between a second drive position located in an internal space of the device housing and a second maintenance position located in an external space of the device housing; a first detection unit that detects that the first head unit has moved between the first drive position and the first maintenance position and outputs a first detection signal; a second detection unit that detects that the second head unit has moved between the second drive position and the second maintenance position and outputs a second detection signal; an input unit that receives a first command including a command to switch the first ink ejection surface from the capped state to the decapped state, and outputs a first input signal when the first command is received, and that receives a second command including a command to switch the second ink ejection surface from the capped state to the decapped state, and outputs a second input signal when the second command is received; a control unit electrically connected to each of the first ejection head, the first movement mechanism, the first detection unit, the second ejection head, the second movement mechanism, the second detection unit, and the input unit; and The control unit a) when it is detected that the first head unit has moved from the first drive position to the first maintenance position based on the first detection signal input from the first detection unit while the first input signal is input from the input unit, after a first predetermined time has elapsed, controlling the first movement mechanism to switch the first ink ejection surface from the capped state to the decapped state; b) when it is detected that the second head unit has moved from the second drive position to the second maintenance position based on the second detection signal input from the second detection unit while the second input signal is input from the input unit, after a second predetermined time has elapsed, controlling the second movement mechanism to switch the second ink ejection surface from the capped state to the decapped state; an inkjet printing device capable of performing the above steps.

2. 10. The inkjet printing apparatus of claim 1, The control unit after step a), when it is detected that the first head unit has moved from the first maintenance position to the first drive position based on the first detection signal input from the first detection unit, the first moving mechanism is controlled to switch the first ink ejection surface from the decapped state to the capped state; After step b), when it is detected that the second head unit has moved from the second maintenance position to the second drive position based on the second detection signal input from the second detection unit, the inkjet printing device controls the second movement mechanism to switch the second ink ejection surface from the decapped state to the capped state.

3. 3. The inkjet printing apparatus according to claim 1, The control unit When it is detected that the first head unit has moved from the first drive position to the first maintenance position based on the first detection signal input from the first detection unit in a state in which the first input signal is not input from the input unit, it recognizes this as an error and waits with the first ink ejection surface in the capped state, When the second input signal is not input from the input unit and it is detected that the second head unit has moved from the second drive position to the second maintenance position based on the second detection signal input from the second detection unit, the inkjet printing device recognizes this as an error and waits with the second ink ejection surface in the capped state.

4. 3. The inkjet printing apparatus according to claim 1, a first circulation path including a first supply tank that stores the first ink to be supplied to the first ejection head, a first recovery tank that stores the first ink recovered from the first ejection head, and a first return pipe that connects the first recovery tank and the first supply tank; a first circulation pump that is inserted in the first return pipe and that sends the first ink from the first recovery tank to the first supply tank through the first return pipe; a second circulation path including a second supply tank that stores the second ink to be supplied to the second ejection head, a second recovery tank that stores the second ink recovered from the second ejection head, and a second return pipe that connects the second recovery tank and the second supply tank; a second circulation pump that is inserted in the second return pipe and that sends the second ink from the second recovery tank to the second supply tank through the second return pipe; and the control unit is further electrically connected to each of the first circulation pump and the second circulation pump; The control unit When it is detected that the first head unit has moved from the first driving position to the first maintenance position, the driving of the first circulation pump is stopped; When it is detected that the second head unit has moved from the second drive position to the second maintenance position, the inkjet printing apparatus stops driving the second circulation pump.

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