Liquid discharge device

Abstract

To provide a liquid discharge device that properly cools a substrate, despite that a flow rate of cooling air is insufficient due to abnormality of a cooling source dedicated to substrate cooling or due to limitation of capability.SOLUTION: A liquid discharge device 11 comprises a liquid discharge part 40, a support part 45, and a drive board 50. The liquid discharge device 11 comprises: a first air suction passage 61; a first fan 63; a second air suction passage 71; a second fan 72; a bypass passage 67; and a switching mechanism 80. The first air suction passage 61 suctions air in at least one position out of an upstream side and a downstream side of the liquid discharge part 40, by using suction force of the first fan 63. The second air suction passage 71 feeds outside air to the drive board 50 by the suction force of the second fan 72. The bypass passage 67 feeds air exhausted by the first fan 63, to the second air suction passage 71. The switching mechanism 80 can switch between an open state of allowing communication, and a closed state of not allowing communication, between the by pass passage 67 and the second suction air suction passage 71.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device including a liquid ejection unit that ejects liquid. [Background technology]

[0002] For example, there is an inkjet printing device that is an example of a liquid ejection device that prints by ejecting ink, which is an example of a liquid, from an inkjet head, which is an example of a liquid ejection unit, as described in Patent Document 1. The inkjet head prints by ejecting ink from nozzles onto a print medium that is being transported.

[0003] The technology in Patent Document 1 relates to a printing unit that prints by ejecting ink using an inkjet head. This printing unit efficiently cools the inkjet head using a cooling fan while avoiding problems caused by satellites that occur when ink is ejected. If the internal drive circuit board generates excessive heat, it can cause malfunctions. Therefore, the internal drive circuit board is cooled by flowing air over the surface of the inkjet head.

[0004] In some liquid ejection devices, the drive circuit for the inkjet head is provided separately from the inkjet head. In addition, in liquid ejection devices, not only the drive board but also various electronic circuit mounting boards are cooled using air generated by a cooling source such as a cooling fan. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-126835 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if a malfunction occurs in a cooling source such as a cooling fan, there is no way to cool the electronic circuit board, such as the drive board, until the malfunction is resolved. As a result, printing is not possible during that time, resulting in downtime. Furthermore, if a cooling source with a low capacity is used to prevent the cooling fan or other cooling source from becoming too large, the electronic circuit board may not be sufficiently cooled due to insufficient capacity depending on the usage situation and environment. Thus, if the cooling air flow rate is insufficient due to a malfunction or capacity limit in the cooling source for board cooling, there is a problem in that the electronic circuit board cannot be properly cooled. [Means for solving the problem]

[0007] a first air suction passage that sucks air at least either upstream or downstream of the liquid discharge passage in the direction of relative movement between the medium supported by the support section and the liquid discharge passage and causes the air to flow downstream in the suction direction; a first suction source that generates a suction force capable of sucking air into the first air suction passage; a second air suction passage that supplies external air to the electronic circuit mounting board; a second suction source that generates an air flow in the second air suction passage in a supply direction toward the electronic circuit mounting board; a bypass passage configured to supply air discharged from the first suction source to the second air suction passage; and a switching mechanism configured to switch the bypass passage between an open state that connects the bypass passage to the second air suction passage and a closed state that does not connect the bypass passage to the second air suction passage. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a liquid ejection device according to the first embodiment. [Figure 2] FIG. 2 is a schematic front cross-sectional view showing the liquid ejection device. [Figure 3] FIG. 3 is a schematic cross-sectional side view of the liquid ejection device. [Figure 4] FIG. 4 is a schematic front cross-sectional view showing a device for cooling a drive substrate. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a rotation type switching mechanism. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a sliding type switching mechanism. [Figure 7] FIG. 7 is a block diagram showing the electrical configuration of the liquid ejection device. [Figure 8] FIG. 8 is a schematic front cross-sectional view showing the cooling effect of the drive substrate. [Figure 9] FIG. 9 is a schematic front cross-sectional view showing the cooling effect of the drive substrate. [Figure 10] FIG. 10 is a schematic front cross-sectional view showing the cooling effect of the drive substrate. [Figure 11] FIG. 11 is a schematic front cross-sectional view showing a device for cooling a drive substrate in the second embodiment. [Figure 12] FIG. 12 is a schematic front cross-sectional view showing the cooling effect of the drive substrate. [Figure 13] FIG. 13 is a schematic front cross-sectional view showing the cooling effect of the drive substrate. [Figure 14] FIG. 14 is a schematic front cross-sectional view showing the cooling effect of the drive substrate. [Figure 15] FIG. 15 is a schematic front cross-sectional view showing a device for cooling a drive substrate in the third embodiment. [Figure 16] FIG. 16 is a schematic front cross-sectional view showing the cooling effect of the drive substrate. [Figure 17] FIG. 17 is a schematic front cross-sectional view showing the cooling action of the drive substrate. [Figure 18] FIG. 18 is a schematic front cross-sectional view showing the cooling action of the drive substrate. [Figure 19] FIG. 19 is a schematic front cross-sectional view showing the cooling effect of the drive substrate. [Figure 20] FIG. 20 is a schematic cross-sectional view showing a rotation type switching mechanism in a modified example. [Figure 21] FIG. 21 is a schematic cross-sectional view showing a sliding type switching mechanism in a modified example. [Figure 22] FIG. 22 is a schematic cross-sectional view showing a sliding type switching mechanism in a modified example. [Figure 23] FIG. 23 is a schematic cross-sectional view showing a rotation type switching mechanism in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A first embodiment of a liquid ejection device will be described below with reference to the drawings. The liquid ejection device 11 shown in FIG. 1 is, for example, an inkjet printer that ejects ink, which is an example of a liquid, onto a medium such as paper to perform recording.

[0010] In the drawings, the liquid ejection device 11 is placed on a horizontal plane, with the direction of gravity indicated by the Z axis, and directions along the horizontal plane indicated by the X and Y axes. The X, Y, and Z axes are perpendicular to one another. In the following description, the depth direction X, which is parallel to the X axis, is also the width direction of the medium to be printed on, and therefore will also be referred to as the width direction X. The direction parallel to the Z axis will also be referred to as the vertical direction Z.

[0011] As shown in FIG. 1 , the liquid ejection device 11 may include a device main body 12, an image reading device 13 provided on the device main body 12, and an automatic feeder 14. The device main body 12 has a substantially rectangular parallelepiped shape and includes four side panels 12A to 12D. The four side panels 12A to 12D face the front, right side, left side, and rear, respectively. The image reading device 13 may read an image on a medium 16 recorded by the device main body 12. The automatic feeder 14 feeds the medium 16 to the image reading device 13.

[0012] The liquid ejection device 11 may include an operation unit 15 for performing various operations on the liquid ejection device 11, a medium storage unit 17 capable of storing single sheets of media 16, and a stacker 18 for receiving the ejected media 16. The operation unit 15 may be, for example, a touch panel, a button, a touch pad, or a combination of these. The medium storage unit 17 is capable of storing multiple media 16 in a stacked state. The liquid ejection device 11 may include multiple medium storage units 17. The liquid ejection device 11 of this embodiment includes, for example, four medium storage units 17.

[0013] 2, the liquid ejection device 11 includes a transport unit 20 that transports the medium 16 along a transport path 21. The transport unit 20 transports the medium 16 in a transport direction D. The transport direction D is a direction along the transport path 21.

[0014] The transport path 21 includes a path indicated by a dashed line connecting the upstream medium storage unit 17 and the downstream stacker 18. The transport path 21 may have an upstream feeding path 22, a substantially horizontal feed path 23, and a downstream discharge path 24. The transport path 21 has the same number of feeding paths 22 as the number of medium storage units 17. Each feeding path 22 merges with the feed path 23. The liquid ejection device 11 may have an inversion path (not shown) or an inversion mechanism (not shown) that inverts the medium 16. By inverting the medium 16, recording may be performed on both sides.

[0015] The liquid ejection device 11 may include a feeding unit 26 that feeds the medium 16 from the medium storage unit 17. The number of feeding units 26 may be the same as the number of medium storage units 17. The liquid ejection device 11 may include, for example, four feeding units 26. Each feeding unit 26 feeds the medium 16 stored in the corresponding medium storage unit 17 to the corresponding feeding path 22.

[0016] Feeding unit 26 may include a feeding roller 29 that feeds media 16 stored in medium storage unit 17, and a separation unit 30 that separates media 16 one by one. Feeding unit 26 may also include a roller pair 31 that transports separated media 16 along feeding path 22.

[0017] The liquid ejection device 11 may include a registration roller 32 for correcting skew of the medium 16. The registration roller 32 may be configured as a roller pair. The registration roller 32 corrects skew of the medium 16 and then transports the medium 16 downstream in the transport direction D.

[0018] The liquid ejection device 11 includes a liquid ejection unit 40 that ejects liquid onto the medium 16, and a support unit 45 that supports the medium 16 at a position opposite the liquid ejection unit 40. The liquid ejection unit 40 prints on the medium 16 by ejecting liquid onto the medium 16 transported along the feed path 23. The liquid ejection unit 40 may be a line type that can eject liquid across the width direction X of the medium 16. The liquid ejection unit 40 may have a predetermined length in the width direction X that is slightly longer than the maximum medium width. The liquid ejection device 11 may be a line printer of this type. Note that the liquid ejection unit 40 may also be a serial type that ejects liquid and prints while moving in the width direction X of the medium 16. In other words, the liquid ejection device 11 may be a serial printer.

[0019] The liquid ejection unit 40 has an ejection head 41 at its lower part facing the support unit 45. The ejection head 41 has a nozzle opening surface facing the support unit 45. Nozzles open in the nozzle opening surface. For example, a plurality of nozzles may be provided. The plurality of nozzles may be provided in the width direction X at a nozzle pitch according to the printing resolution. The liquid ejection unit 40 prints characters or images on the medium 16 by ejecting liquid from the nozzles.

[0020] The support section 45 may be a conveyor belt unit including a conveyor belt 46 that supports the medium 16. In this case, the support section 45 may include an endless conveyor belt 46, and a drive pulley 47 and a driven pulley 48 around which the conveyor belt 46 is wound. The drive pulley 47 rotates using the power of a conveyor motor 20M (see FIG. 7 ), which is the drive source of the conveyor section 20. The driven pulley 48 is provided so as to be rotatable about an axis parallel to the axis of the drive pulley 47. The conveyor belt 46 conveys the medium 16 by rotating while supporting the medium 16 on its outer circumferential surface by electrostatic adsorption, for example.

[0021] The liquid ejection device 11 has a charging unit 33 that charges the conveyor belt 46. The charging unit 33 contacts the conveyor belt 46. The charging unit 33 charges the conveyor belt 46 by contacting the outer circumferential surface of the conveyor belt 46. The medium 16 is electrostatically attracted to the charged conveyor belt 46. The charging unit 33 is, for example, a roller to which a voltage is applied. The charging unit 33 rotates together with the rotation of the conveyor belt 46.

[0022] The liquid ejection device 11 may also include a ground roller 34 that stabilizes the potential of the medium 16, and a removal unit 35 that removes paper dust, fine particles, and the like adhering to the medium 16. The removal unit 35 may be, for example, a static elimination unit having a static elimination brush. The static elimination brush performs static elimination, removing the charge on the surface of the medium 16. The static elimination brush also removes foreign matter, such as paper dust, adhering to the charged surface of the medium 16. The foreign matter removed by the removal unit 35 may be collected by a foreign matter collection device (not shown).

[0023] The transport unit 20 may include a discharge unit 36. The discharge unit 36 ​​transports the medium 16 after recording along the transport path 21 to the stacker 18. The discharge unit 36 ​​includes a plurality of transport roller pairs 49 provided along the transport path 21. The transport roller pairs 49 may include one that discharges the medium 16 along the discharge path 24. The transport roller pairs 49 transport the medium 16 by rotating while sandwiching the medium 16 between them.

[0024] The liquid discharge device 11 includes a mist collection device 60 and an air cooling device 70 (see FIG. 3). The mist collection device 60 includes a first air suction passage 61 and a first fan 63 as an example of a first suction source.

[0025] The first air suction passage 61 sucks air downstream of the liquid discharger 40 in the transport direction D, which is the direction of relative movement between the medium 16 supported by the support member 45 and the liquid discharger 40, and causes the air to flow downstream in the suction direction. The first air suction passage 61 may have a suction port at a position where it can suck air between the liquid discharger 40 and the support member 45.

[0026] The first fan 63 generates a suction force capable of sucking air into the first air suction passage 61. The first fan 63 is a mist collection fan that generates a suction force to collect mist that is generated when the liquid discharger 40 discharges liquid.

[0027] The first air suction passage 61 has a mist suction section 62 in its upstream portion. The mist suction section 62 sucks in mist that is generated when the ejection head 41 ejects droplets from the nozzles. Air containing the sucked mist flows in the suction direction along the first air suction passage 61. The mist collection device 60 has a collection section 64 connected to the downstream end of the first air suction passage 61. The collection section 64 collects mist and other particles contained in the air. The first fan 63 exhausts the air after the mist has been collected.

[0028] The liquid ejection device 11 includes a drive substrate 50, which is an example of an electronic circuit mounting substrate. The drive substrate 50 outputs a drive signal to the liquid ejection unit 40. The liquid ejection unit 40 ejects liquid from the nozzles based on the drive signal.

[0029] The drive substrate 50 generates heat when performing ejection control to cause the liquid ejection section 40 to eject liquid. Therefore, the liquid ejection device 11 is provided with an air-cooling device 70 that cools the drive substrate 50. The drive substrate 50 is cooled by air cooling provided by the air-cooling device 70.

[0030] The liquid ejection device 11 includes a control unit 100 that controls the liquid ejection device 11. The control unit 100 controls the transport unit 20, the mist collection unit 60, and the air-cooling unit 70 (see FIG. 3), etc. The control unit 100 is communicably connected to a drive substrate 50. The control unit 100 inputs print data PD (see FIG. 7). The control unit 100 transmits image data and the like in the print data PD to the drive substrate 50. The drive substrate 50 controls the liquid ejection unit 40 based on the image data and the like, thereby ejecting liquid such as ink from the nozzles of the ejection head 41.

[0031] The drive board 50 may include, for example, an ASIC (Application Specific Integrated Circuit). The drive board 50 may include a CPU that executes a program. The drive board 50 may include an ASIC and a CPU.

[0032] The control unit 100 is composed of, for example, a processing circuit including a computer and memory. The control unit 100 controls the transport unit 20, mist collection device 60, air cooling device 70, etc. in accordance with programs stored in the memory. The control unit 100 is electrically connected to the drive substrate 50 so as to be able to exchange data and signals with the drive substrate 50. The control unit 100 performs the communication required to control the drive substrate 50 and the liquid ejection unit 40. The control unit 100 transmits image data and the like contained in the input print data PD to the drive substrate 50. The drive substrate 50 generates a drive signal based on the image data and the like.

[0033] <Configuration of the mist collection device 60 and the air-cooling device 70> Next, the configurations of the mist collection device 60 and the air-cooling device 70 will be described with reference to FIGS.

[0034] 3, the inside of the device main body 12 is divided into a first chamber 19A and a second chamber 19B. The first chamber 19A and the second chamber 19B are divided by a partition plate 12F provided inside the device main body 12. The partition plate 12F is used for assembling, for example, the conveying unit 20, the liquid discharge unit 40, etc. The first chamber 19A and the second chamber 19B may have a portion that communicates with each other via a hole or opening in the partition plate 12F.

[0035] 3 and 4, the mist collecting device 60 is disposed across the first chamber 19A and the second chamber 19B. The air-cooling device 70 is housed in the second chamber 19B. The liquid ejection device 11 includes a housing portion 51 that houses the drive substrate 50. The drive substrate 50 is housed in the housing portion 51 that is arranged at a predetermined height in the second chamber 19B of the device body 12. The housing portion 51 may be, for example, a housing box. The housing portion 51 may constitute a part of the air-cooling device 70. In other words, the air-cooling device 70 may include the housing portion 51.

[0036] The accommodation section 51 is used as a cooling box through which air flows to cool the drive substrate 50. The accommodation section 51 has an air inlet 51A and an air outlet 51B on both sides of its longitudinal direction (for example, the Y direction). Air flows in the +Y direction from the inlet 51A to the air outlet 51B within the accommodation section 51. The drive substrate 50 accommodated in the accommodation section 51 is cooled by the air flowing in the +Y direction. In this way, the air-cooling device 70 cools the drive substrate 50 by air cooling.

[0037] The mist collection device 60 includes the first air suction passage 61 and the first fan 63 described above. The first fan 63 generates a suction force capable of drawing air into the first air suction passage 61. The first fan 63 has a rotatable fan 63F (see FIG. 3, not shown in FIG. 4) inside it. The first fan 63 may be an axial fan or a centrifugal fan. As the fan 63F rotates, the first fan 63 draws in air from the intake port and exhausts it from the exhaust port. The suction force acting on the intake port of the first fan 63 reaches the first air suction passage 61.

[0038] As shown in Figure 4, the first air suction passage 61 sucks air at a position downstream of the liquid discharger 40 in the transport direction D, which is the direction of relative movement between the medium 16 supported by the support member 45 and the liquid discharger 40. The first air suction passage 61 flows the sucked air downstream in the suction direction Dm (see Figure 4). In this embodiment, the first air suction passage 61 sucks air between the support member 45 and the liquid discharger 40 and flows it downstream in the suction direction Dm.

[0039] The first air suction passage 61 includes a mist suction section 62 and a first suction duct 65. The mist suction section 62 is disposed downstream of the discharge head 41 in the conveying direction D. As shown in FIG. 3, the mist suction section 62 extends along the longitudinal direction of the discharge head 41. The mist suction section 62 has a suction nozzle section 66 (see FIG. 4) that extends obliquely downward toward the discharge head 41. The suction nozzle section 66 has a first suction port 62A that opens at its lower end. The first suction port 62A is disposed at a height position in the vertical direction Z that allows it to suck air between the liquid discharge section 40 and the support section 45. The first suction port 62A is located, for example, above a support surface 45A, which is the upper surface of the support section 45, and below the upper surface of the liquid discharge section 40, in the vertical direction Z. In the example shown in FIGS. 3 and 4, the first suction port 62A is located above a nozzle surface, which is the lower surface of the discharge head 41. For example, the first suction port 62A may be located above the discharge head 41. In other words, as long as the first suction port 62A can suck in air between the discharge head 41 and the support part 45, the height position in the vertical direction Z may be changed as appropriate.

[0040] The first suction duct 65 extends from the first chamber 19A across the partition plate 12F to the second chamber 19B. The downstream end of the first suction duct 65 is connected to the intake port of the collection unit 64 arranged in the second chamber 19B. The exhaust port side of the collection unit 64 is connected to the first fan 63.

[0041] The collection unit 64 collects mist contained in the sucked air. The collection unit 64 has a filter 64F inside. The first fan 63 sucks the air from which the mist has been removed by the filter 64F through the intake port and expels the air through the exhaust port.

[0042] 3 and 4, the air-cooling device 70 includes a second air suction passage 71 and a second fan 72, which is an example of a second suction source. The second fan 72 is a cooling fan that generates a suction airflow and is therefore an example of a suction source, but is also an example of a cooling source for cooling an electronic circuit mounting board.

[0043] The second air suction passage 71 supplies external air to the drive substrate 50. The second air suction passage 71 extends in a predetermined direction. In the example shown in FIG. 4, the second air suction passage 71 extends, for example, in the vertical direction Z. The second air suction passage 71 has a second suction port 71A at one end in the longitudinal direction thereof, which sucks in air external to the device body 12. An air vent (not shown) opens in the side plate 12B on the right side of the device body 12, at a position opposite the second suction port 71A. The air vent may be composed of multiple holes. The second air suction passage 71 sucks in air external to the side plate 12B from the second suction port 71A through the air vent. The air sucked in from the second suction port 71A flows through the second air suction passage 71 in the feed direction Df. The downstream end of the second air suction passage 71 in the feed direction Df is connected to the intake port 51A of the storage unit 51.

[0044] The second fan 72 generates an air flow in the second air suction passage 71 in the feeding direction Df toward the drive substrate 50. The second fan 72 includes a rotatable fan 72F (see FIG. 3, not shown in FIG. 4) therein. The second fan 72 may be an axial fan or a centrifugal fan.

[0045] The second fan 72 is disposed at one end of the housing section 51 on the exhaust port 51B side in the longitudinal direction (air flow direction). In the example shown in FIG. 4, the second fan 72 is disposed such that the exhaust port 51B, which opens on the top surface of the housing section 51, is in communication with an intake port (not shown) thereof. The intake port of the second fan 72 is in communication with the exhaust port 51B. The second fan 72 draws air through the exhaust port 51B, which is located near one end of the housing section 51. The second fan 72 has an exhaust port 72A through which the drawn air is exhausted. When the second fan 72 draws air from inside the housing section 51 through the exhaust port 51B, the air drawn into the second air suction passage 71 from the second suction port 71A further flows within the housing section 51 in a direction from the intake port 51A toward the exhaust port 51B (+Y direction). The drive substrate 50 is cooled by the air flowing within the housing section 51. The air used to cool the drive substrate 50 is exhausted from the exhaust port 72A of the second fan 72. The air exhausted from the exhaust port 72A is further exhausted to the outside of the device body 12 from a vent opening in the side panel 12D on the rear side.

[0046] 4, the liquid discharger 11 includes a bypass passage 67 connected to an exhaust port (not shown) of the first fan 63. The bypass passage 67 selectively connects the exhaust port of the first fan 63 to a second air suction passage 71. The bypass passage 67 is configured to be able to feed air discharged from the first fan 63 to the second air suction passage 71. The bypass passage 67 of this embodiment includes a first bypass passage 68 and a second bypass passage 73.

[0047] The first bypass passage 68 extends from the exhaust port of the first fan 63 toward the position of the second air suction passage 71 (for example, the -Y direction). The upstream end of the first bypass passage 68 in the discharge direction De is connected to the exhaust port (not shown) of the first fan 63. The first bypass passage 68 extends approximately horizontally to a position near the second air suction passage 71. The air exhausted by the first fan 63 flows in the discharge direction De through the first bypass passage 68. The downstream end of the first bypass passage 68 in the discharge direction De is located closer to the second air suction passage 71 than the first fan 63.

[0048] The second bypass passage 73 is a passage branching off from a midpoint of the second air suction passage 71. The second bypass passage 73 extends a predetermined length from a midpoint of the second air suction passage 71 toward upstream in the discharge direction De. In the discharge direction De, the upstream end of the second bypass passage 73 faces the downstream end of the first bypass passage 68. The second bypass passage 73 has a shape that can receive air discharged from the downstream end of the first bypass passage 68 in the discharge direction De. The second bypass passage 73 does not necessarily have to be cylindrical as long as it can receive air discharged from the downstream end of the first bypass passage 68 in the discharge direction De. The second bypass passage 73 may be, for example, a plate-like guide plate extending at an angle that can receive air, as shown in FIG. 4 .

[0049] 4, the liquid discharger 11 is provided with a switching mechanism 80 in the bypass passage 67 that can switch the destination of the air to be discharged. More specifically, the switching mechanism 80 is configured to be able to switch the destination of the air to be discharged from the first bypass passage 68. The switching mechanism 80 is configured to be able to switch between an open state in which the bypass passage 67 is connected to the second air suction passage 71, and a closed state in which the bypass passage 67 is not connected to the second air suction passage 71. In other words, the switching mechanism 80 is configured to be able to switch between an open state in which the air discharged from the first bypass passage 68 can be fed into the second air suction passage 71, and a closed state in which the air is not fed into the second air suction passage 71.

[0050] More specifically, the switching mechanism 80 has an opening / closing plate 81. The opening / closing plate 81 is configured to be movable between a closed position indicated by a solid line in Fig. 4 and an open position indicated by a two-dot chain line in Fig. 4. When in the closed position, the opening / closing plate 81 closes the communication passage between the first bypass passage 68 and the second bypass passage 73. When the opening / closing plate 81 is in the closed position, air discharged from the first bypass passage 68 is exhausted into the device body 12 along the surface of the opening / closing plate 81 which is in the closed position.

[0051] On the other hand, when the opening / closing plate 81 of the switching mechanism 80 is in the open position, the first bypass passage 68 and the second bypass passage 73 are connected to each other. Therefore, air discharged from the first bypass passage 68 passes through the second bypass passage 73 and is fed into the second air suction passage 71. In other words, when the opening / closing plate 81 is in the open position, air discharged from the first bypass passage 68 is received by the second bypass passage 73 and is fed into the second air suction passage 71.

[0052] As shown in Fig. 4, the first bypass passage 68 has a flow velocity acceleration section 69 at its downstream portion in the discharge direction De, which has a tapered shape such that the cross-sectional area of ​​the passage becomes smaller toward the downstream side. In this way, the portion of the bypass passage 67 leading to the switching mechanism 80 in the discharge direction De is formed in a tapered shape such that the cross-sectional area of ​​the passage is smaller downstream than upstream. The flow velocity of the air discharged from the downstream end of the first bypass passage 68 is accelerated by the flow velocity acceleration section 69 having a tapered shape. Therefore, air is discharged from the downstream end of the first bypass passage 68 at a high flow velocity.

[0053] The tapered flow velocity acceleration section 69 also functions as a guide that directs the air flowing into the second air suction passage 71 in the feeding direction Df. The inclination angle of the inner surface of the flow velocity acceleration section 69 guides the air flowing from the first bypass passage 68 into the second air suction passage 71 in the feeding direction Df. The second bypass passage 73 and the opening / closing plate 81 in the closed position also guide the air in this directing direction.

[0054] <Configuration of the switching mechanism 80> Next, the configuration of the switching mechanism 80 will be described with reference to FIG. The opening / closing plate 81 of the switching mechanism 80 may be of a rotating type or a sliding type. The switching mechanism 80 employs a rotating type in which the switching operation of the opening / closing plate 81 involves a rotating motion as shown in Fig. 5. Alternatively, the switching mechanism 80 may employ a sliding type in which the switching operation of the opening / closing plate 81 involves a sliding motion as shown in Fig. 6. The configurations of the switching mechanisms 80 for the rotating type and the sliding type will be described below.

[0055] First, the configuration of a rotation-type switching mechanism 80 will be described with reference to Fig. 5. The switching mechanism 80 shown in Fig. 5 includes a rotation-type opening / closing plate 81. The opening / closing plate 81 has a plate shape of a predetermined shape. The opening / closing plate 81 is provided so as to be rotatable within a predetermined angular range around a rotation shaft 82. Air with a high flow rate is discharged from the downstream end of a flow rate acceleration section 69 that is tapered and formed in the downstream portion of the first bypass passage 68.

[0056] The opening / closing plate 81 is rotatably provided at a position facing the downstream end of the flow velocity acceleration unit 69. The opening / closing plate 81 is rotatable between a closed position indicated by a two-dot chain line in Fig. 5 and an open position indicated by a solid line in Fig. 5. The liquid discharger 11 includes an actuator 83 that is a drive source for opening and closing the opening / closing plate 81, and a power transmission unit 84 that converts the power of the actuator 83 into opening and closing operation of the opening / closing plate 81. The opening / closing plate 81 opens and closes when forward and reverse power from the actuator 83 is transmitted to a rotation shaft 82 of the opening / closing plate 81.

[0057] 5, the opening / closing plate 81 blocks communication between the bypass passage 67 and the second air suction passage 71. When in the closed position, the opening / closing plate 81 guides the air discharged from the first bypass passage 68 in the discharge direction De along the surface of the opening / closing plate 81 in the exhaust direction where the air is exhausted into the device body 12.

[0058] 5, the bypass passage 67 communicates with the second air suction passage 71. Therefore, when the opening / closing plate 81 is in the open position, the high-velocity air discharged from the first bypass passage 68 in the discharge direction De flows into the second air suction passage 71 via the second bypass passage 73.

[0059] 6 has an opening / closing plate 81 that is provided so as to be able to slide in a predetermined direction. The opening / closing plate 81 has a size that allows it to close the second bypass passage 73.

[0060] The opening / closing plate 81 can be slid between a closed position indicated by a two-dot chain line in Fig. 6 and an open position indicated by a solid line in Fig. 6. The liquid discharger 11 includes an actuator 83 that is a drive source for opening and closing the opening / closing plate 81, and a power transmission unit 84 that converts the power of the actuator 83 into a sliding movement of the opening / closing plate 81. The opening / closing plate 81 opens and closes when the power of the actuator 83 transmits power for sliding in a predetermined direction.

[0061] 6, the second bypass passage 73 is closed. The air discharged from the first bypass passage 68 is exhausted into the device body 12 along the surface of the opening and closing plate 81 in the closed position. The second bypass passage 73 has a guide plate portion 73A that guides the air discharged from the first bypass passage 68 into the device body 12 together with the opening and closing plate 81 in the closed position.

[0062] When the opening / closing plate 81 of the switching mechanism 80 is in the open position shown by the solid line in FIG. 6, the air discharged from the first bypass passage 68 flows into the second air suction passage 71 through the second bypass passage 73.

[0063] <Electrical configuration of the liquid ejection device 11> Next, the electrical configuration of the liquid ejection device 11 will be described with reference to Fig. 7. As shown in Fig. 7, the liquid ejection device 11 includes the above-mentioned control unit 100 and drive substrate 50. The control unit 100 and the ejection control unit 52 are connected so as to be able to communicate with each other.

[0064] The control unit 100 performs overall control of the liquid ejection device 11. The control unit 100 is electrically connected to a first detection unit 101 and a second detection unit 102, which are examples of detection units, via an input interface (not shown). The first detection unit 101 detects the temperature inside the storage unit 51. The second detection unit 102 detects the size of the medium 16.

[0065] Furthermore, the control unit 100 is electrically connected to the transport unit 20, the charging unit 33, the removal unit 35, the first fan 63, the second fan 72, and the switching mechanism 80 via an output interface (not shown). The control unit 100 controls the transport unit 20, the charging unit 33, the removal unit 35, the first fan 63, the second fan 72, and the switching mechanism 80.

[0066] The control unit 100 may be configured as a circuit including: α: one or more processors that execute various processes according to a computer program; β: one or more dedicated hardware circuits that execute at least some of the various processes; or γ: a combination thereof. The hardware circuit is, for example, an application-specific integrated circuit. The processor includes a CPU and a storage unit consisting of memories such as RAM and ROM. The storage unit stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any readable medium accessible by a general-purpose or dedicated computer.

[0067] The control unit 100 stores a program in a storage unit of a computer. The computer executes the program in the control unit 100. The control unit 100 includes a transport control unit 111, a printing speed acquisition unit 112, an abnormality detection unit 113, and the like, which are configured by software.

[0068] The control unit 100 receives print data PD from a host device (not shown). The print data PD includes print condition information and image data. The print condition information includes information such as the type of medium 16 (medium type), medium size, print mode, and print color (color / monochrome). The image data is dot data that includes, for each pixel, a density value (pixel value) corresponding to the amount of liquid, such as ink, that the liquid ejection unit 40 ejects from multiple nozzles.

[0069] The drive substrate 50 is equipped with a discharge control unit 52. The discharge control unit 52 controls the liquid discharge unit 40. The discharge control unit 52 receives image data and the like from the control unit 100. The discharge control unit 52 discharges droplets from the nozzles at a discharge volume corresponding to the density value of each pixel (dot) of the image data. A plurality of droplets land on the medium 16 to form a plurality of dots, thereby printing characters or images on the medium 16. The pixel value of the image data corresponds to the amount of liquid discharged onto the medium 16. The greater the amount of liquid discharged, the more power is consumed to drive the discharge elements.

[0070] The discharge control unit 52 drives the discharge elements that the liquid discharge unit 40 has for each nozzle based on image data. The discharge elements are driven to discharge liquid from the nozzles. Examples of discharge elements include piezoelectric elements, electrostatic elements, and heater elements. The discharge control unit 52 controls each discharge element by outputting a duty value (duty ratio), which is the ratio of applied power to maximum power, as a command value to the discharge element.

[0071] The transport control unit 111 controls the transport unit 20. The transport control unit 111 controls the drive of the transport unit 20 at a drive speed according to the print mode, so that the medium 16 is transported at a transport speed according to the print mode.

[0072] The print speed acquisition unit 112 acquires print speed information based on the print data PD. The print data PD includes print mode information as one piece of print condition information. There are multiple print modes, including a first print mode and a second print mode. The first print mode is, for example, a high-resolution print mode, and the second print mode is, for example, a high-speed print mode. The second print speed in the second print mode is faster than the first print speed in the first print mode. The faster the print speed, the more likely the drive substrate 50 is to generate heat.

[0073] The abnormality detection unit 113 detects abnormalities such as failures of various drive system components in the liquid ejection device 11. The abnormality detection unit 113 detects abnormalities in, for example, the first fan 63, the second fan 72, the transport motor, etc. The abnormality detection unit 113 detects an abnormality such as a failure of the second fan 72 when it receives a detection signal indicating that a rotation sensor (not shown) capable of detecting rotation of the second fan 72 is not detecting rotation despite a drive command value being output to the second fan 72. Alternatively, the abnormality detection unit 113 may detect an abnormality such as a failure of the second fan 72 when it receives a detection signal indicating that a rotation sensor (not shown) capable of detecting rotation of the second fan 72 is not detecting rotation despite a drive command value being output to the second fan 72.

[0074] When the liquid discharger 40 performs a liquid discharge operation while an abnormality has occurred in the second fan 72, the control unit 100 stops the second fan 72 and opens the switching mechanism 80. That is, when the control unit 100 detects an abnormality in the second fan 72 and causes the liquid discharger 40 to perform a liquid discharge operation based on the print data PD, the control unit 100 stops the second fan 72 and opens the switching mechanism 80. When the liquid discharge operation is performed, the control unit 100 drives the first fan 63 to collect mist. Therefore, air discharged by the first fan 63 flows from the bypass passage 67 into the second air suction passage 71 via the switching mechanism 80, which is in the open state.

[0075] The first detection unit 101 detects the temperature of the drive substrate 50. The first detection unit 101 may indirectly detect the temperature of the drive substrate 50 by detecting the temperature inside the accommodation unit 51. The first detection unit 101 may also directly detect the temperature of the drive substrate 50. The first detection unit 101 may be, for example, a temperature sensor or a temperature and humidity sensor. Furthermore, the first detection unit 101 may be provided on the drive substrate 50.

[0076] The control unit 100 may control the switching mechanism 80 based on the temperature detected by the first detection unit 101. The control unit 100 maintains the switching mechanism 80 in the closed position while the temperature detected by the first detection unit 101 is equal to or lower than the temperature threshold. On the other hand, the control unit 100 may switch the switching mechanism 80 from the closed position to the open position when the temperature detected by the first detection unit 101 exceeds the temperature threshold.

[0077] When the switching mechanism 80 is in the open state, the control unit 100 may drive the first fan 63 at an operating speed corresponding to the temperature detected by the first detection unit 101. In this case, the control unit 100 may increase the operating speed of the first fan 63 stepwise or continuously as the detected temperature of the first detection unit 101 increases. When the switching mechanism 80 is in the open state, the control unit 100 may drive the first fan 63 at a second operating speed that is faster than the first operating speed when the temperature detected by the first detection unit 101 is the first temperature, and at a second operating speed that is faster than the first operating speed when the temperature detected by the first detection unit 101 is the second temperature that is higher than the first temperature. Through this control, when the switching mechanism 80 is in the open state, the first fan 63 is driven at a higher operating speed when the temperature detected by the first detection unit 101 is the second temperature that is higher than the first temperature.

[0078] The second detection unit 102 may be a width sensor that detects the width size of the medium 16. The larger the size of the medium 16 onto which the liquid is to be ejected, the greater the number of nozzles used to eject the liquid in the liquid ejection unit 40, and therefore the more likely the drive substrate 50 to generate heat. When the size of the medium 16 is a first size, the drive substrate 50 of the liquid ejection unit 40 is more likely to generate heat when printing on a second size larger than the first size. The control unit 100 may switch the switching mechanism 80 from the closed position to the open position when the size of the medium 16 exceeds the size threshold.

[0079] When the switching mechanism 80 is in the open state, the control unit 100 may drive the first fan 63 at a higher operating speed when the size of the medium 16 is a second size, which is larger than the first size, than when the size of the medium 16 is a first size. In this case, the control unit 100 may increase the operating speed of the first fan 63 in a stepwise or continuous manner as the size of the medium 16 detected by the second detection unit 102 increases.

[0080] The control unit 100 may control the switching mechanism 80 based on the duty value. In this case, the duty value may be an average duty value calculated from the density values ​​of all pixels or a portion of a pixel group of the image data. The average duty value may be, for example, an average duty value per image or an average duty value for multiple images. When the duty value exceeds a threshold, the control unit 100 may switch the switching mechanism 80 from a closed state to an open state. Furthermore, when the duty value exceeds a threshold, the control unit 100 may control the first fan 63 to operate at a higher speed.

[0081] The control unit 100 may control the switching mechanism 80 according to the print mode or the print speed. The control unit 100 may maintain the switching mechanism 80 in the closed position during the first print mode. The control unit 100 may switch the switching mechanism 80 from the closed position to the open position during the second print mode. The control unit 100 may control the opening and closing of the switching mechanism 80 according to the print speed obtained from the print mode. The control unit 100 may maintain the switching mechanism 80 in the closed position during the first print speed. The control unit 100 may switch the switching mechanism 80 from the closed position to the open position during the second print speed, which is faster than the first print speed or which results in a higher temperature of the drive substrate 50.

[0082] When the switching mechanism 80 is in the open state, the control unit 100 may drive the first fan 63 at an operating speed that corresponds to the print mode or the print speed. In this case, the control unit 100 may increase the operating speed of the first fan 63 in a stepwise or continuous manner as the print mode or the print speed becomes faster. When the switching mechanism 80 is in the open state, the control unit 100 may drive the first fan 63 at a higher operating speed when the print speed is a second print speed that is faster than the first print speed than when the print speed is a first print speed.

[0083] The above-mentioned detected temperature, duty value, print mode (or print speed), medium size, etc. are parameters that affect heat generation in the drive substrate 50. The control unit 100 may control the switching mechanism 80 based on one or more of these parameters. When the switching mechanism 80 is in the open state, the control unit 100 may control the operating speed of the first fan 63 based on one or more of these parameters.

[0084] <Operation of the First Embodiment> The operation of the liquid ejection device 11 in this embodiment will be described below. Note that the following description will be given taking an example in which the control unit 100 uses the temperature detected by the first detection unit 101 as a parameter for controlling the switching mechanism 80.

[0085] During printing, the liquid ejection unit 40 prints on the medium 16 by ejecting liquid from the nozzles. When the liquid is ejected from the nozzles, mist is generated. The mist around the liquid ejection unit 40 is collected by the mist collection device 60. When the first fan 63 is driven, the suction nozzle unit 66 sucks in the air between the ejection head 41 and the support unit 45 along with the mist. The mist in the air sucked through the first air suction passage 61 is collected by the collector 64, and the air is then discharged from the first fan 63 through the first bypass passage 68. When the switching mechanism 80 is in the closed position, the air discharged from the first bypass passage 68 is discharged into the device body 12 along the surface of the opening / closing plate 81, which is in the closed position. The discharged air is then discharged to the outside through the ventilation holes in the device body 12.

[0086] During printing, the air-cooling device 70 is driven. When the second fan 72 is driven, air is sucked in through the suction port 71A and flows into the housing section 51 through the second air suction passage 71. The drive substrate 50, which generates heat during printing, is cooled by the air flowing through the housing section 51 from the intake port 51A toward the exhaust port 51B.

[0087] When the temperature inside the accommodation unit 51 detected by the first detection unit 101 is equal to or lower than the temperature threshold, the control unit 100 closes the switching mechanism 80, as shown in Fig. 8. As a result, the air discharged from the first fan 63 is guided to the surface of the opening / closing plate 81 in the closed position and exhausted into the device main body 12.

[0088] When the temperature inside the accommodation unit 51 detected by the first detection unit 101 exceeds the temperature threshold, the control unit 100 switches the switching mechanism 80 from the closed state to the open state, as shown in Fig. 9. That is, the control unit 100 moves the opening / closing plate 81 from the closed position shown in Fig. 8 to the open position shown in Fig. 9. As a result, air discharged from the first fan 63 through the first bypass passage 68 flows into the second air suction passage 71. As a result, the airflow sucked in by the second fan 72 and the airflow discharged from the first fan 63 join together and are sent into the accommodation unit 51.

[0089] The increased flow rate of air cooling the drive substrate 50 improves the cooling effect of the drive substrate 50. This prevents the drive substrate 50 from excessively increasing in temperature. When the temperature detected by the first detection unit 101 falls below the temperature threshold, the control unit 100 returns the switching mechanism 80 from the open state to the closed state. In this way, the control unit 100 controls the opening and closing of the switching mechanism 80 in accordance with the detected temperature, thereby enabling the drive substrate 50 to be effectively cooled with air at an appropriate flow rate in accordance with the heat generated by the drive substrate 50.

[0090] On the other hand, if the control unit 100 detects an abnormality, such as a failure of the second fan 72, it stops the second fan 72. Furthermore, as shown in FIG. 10 , the control unit 100 switches the switching mechanism 80 from the closed state to the open state. Air discharged from the first fan 63 through the first bypass passage 68 flows into the second air suction passage 71. At this time, the tapered flow velocity acceleration section 69 allows a high-velocity airflow to flow into the second air suction passage 71. The airflow flows into the second air suction passage 71 in the air supply direction Df, and is then supplied from the second air suction passage 71 into the housing 51. Therefore, even if an abnormality occurs in the second fan 72, the drive substrate 50 in the housing 51 can be cooled.

[0091] In addition, when the switching mechanism 80 is in the open state, the control unit 100 may control the operating speed of the third fan 92 based on at least one parameter such as the detected temperature, the duty value, the printing speed, and the medium size.

[0092] When the switching mechanism 80 is in the open state, the control unit 100 may increase the operating speed of the first fan 63 from the first speed to the second speed if the detected temperature exceeds the temperature threshold. When the switching mechanism 80 is in the open state, the control unit 100 may increase the operating speed of the first fan 63 from the first speed to the second speed if the duty value exceeds the threshold. Furthermore, when the switching mechanism 80 is in the open state, the control unit 100 may increase the operating speed of the first fan 63 from the first speed to the second speed if the medium size detected by the second detection unit 102 exceeds the size threshold. Furthermore, when the switching mechanism 80 is in the open state, the control unit 100 may increase the operating speed of the first fan 63 from the first speed to the second speed if the printing speed corresponding to the printing mode exceeds the threshold. Note that the control unit 100 may use the printing mode as a determination target instead of the printing speed.

[0093] In these cases, increasing the operating speed of the first fan 63 from the first speed to the second speed increases the flow rate of air flowing through the housing section 51. Therefore, even if the amount of heat generated by the drive substrate 50 increases due to a parameter value (detected temperature, duty value, printing speed, medium size, etc.) exceeding a threshold, the drive substrate 50 can be appropriately cooled. Note that by setting three or more thresholds, the control section 100 may control the operating speed of the third fan 92 in three or more stages. Furthermore, the control section 100 may control the operating speed of the second fan 72 in multiple stages based on the above parameters.

[0094] <Effects of the first embodiment> The effects of this embodiment will be described. (1-1) The bypass passage 67 is provided with a switching mechanism 80 that can switch between an open state in which the bypass passage 67 is connected to the second air suction passage 71 and a closed state in which the bypass passage 67 is not connected to the second air suction passage 71. Therefore, by switching the switching mechanism 80 from the closed state to the open state, the air discharged by the first fan 63 can be used to cool the drive substrate 50. Therefore, even if the flow rate of the second fan 72 is insufficient due to an abnormality or a capacity limit, the drive substrate 50 can be appropriately cooled with air at an appropriate flow rate. For example, liquid ejection can be performed even when an abnormality occurs in the second fan 72, thereby reducing downtime. Furthermore, even if the flow rate is insufficient due to a capacity limit of the second fan 72, the air discharged from the first fan 63 can be used to cool the drive substrate 50. Therefore, it is possible to prevent the second fan 72, dedicated to cooling the drive substrate, from becoming larger due to increased capacity.

[0095] (1-2) When the liquid discharger 40 performs liquid discharge operation while an abnormality occurs in the second fan 72, the second fan 72 is stopped and the switching mechanism 80 is set to the open state. This makes it possible to prevent downtime caused by an abnormality in the second fan 72, which prevents liquid discharge operation from being performed.

[0096] (1-3) The control unit 100 opens the switching mechanism 80 when the temperature detected by the first detection unit 101, which detects the temperature inside the accommodation unit 51 that accommodates the drive substrate 50, exceeds the temperature threshold. Therefore, when the temperature inside the accommodation unit 51 exceeds the target temperature, the cooling effect of the drive substrate 50 can be improved by using the air blown by the first fan 63. This reduces the time required to reduce the temperature inside the accommodation unit 51 to the target temperature. For example, the time during which the drive substrate 50 is exposed to a temperature exceeding the target temperature can be reduced.

[0097] (1-4) The first fan 63 is a mist collection fan that generates suction force to collect mist that is generated when the liquid discharger 40 discharges liquid. With this configuration, not only can the mist that is generated when the liquid discharger 40 discharges liquid be collected, but the air discharged by the mist collection fan can be used to cool the drive substrate 50. Therefore, by using an existing fan 63 or a fan provided for the purpose of adding another function without adding a new fan, it is possible to reduce the size of the second fan 72 that is dedicated to cooling the drive substrate and to continue discharging liquid even when the second fan 72 fails.

[0098] (1-5) When the switching mechanism 80 is in the open state, the first fan 63 operates at a higher operating speed when the temperature detected by the first detection unit 101 is a second temperature that is higher than the first temperature than when the temperature is the first temperature. According to the above configuration, when the switching mechanism 80 is in the open state, the first fan 63 operates at an operating speed that corresponds to the detected temperature inside the accommodation unit 51, and therefore, can supply air to the drive substrate 50 at a flow rate appropriate for cooling.

[0099] (1-6) The portion of the bypass passage 67 leading to the switching mechanism 80 in the discharge direction De is tapered so that the cross-sectional area is smaller downstream than upstream. In this embodiment, the downstream portion of the first bypass passage 68 is tapered. Therefore, when the switching mechanism 80 is in the open state, a decrease in the flow rate of air flowing from the bypass passage 67 into the second air suction passage 71 can be suppressed. Furthermore, the tapered flow rate acceleration section 69 guides the airflow in the air supply direction Df. This prevents the airflow from the bypass passage 67 from merging with the airflow in the air supply direction Df, which would interfere with the flow of air drawn from the second suction port 71A. Furthermore, when an abnormality occurs in the second fan 72, a high-speed airflow directed in the air supply direction Df can be supplied from the bypass passage 67 to the second air suction passage 71.

[0100] (1-7) The switching mechanism 80 has an opening / closing plate 81. The opening / closing plate 81 is of a rotating or sliding type. With this configuration, the simple configuration of rotating or sliding the opening / closing plate 81 makes it easy to switch between merging and non-merging of air.

[0101] [Second embodiment] Next, a second embodiment of the liquid ejection device will be described with reference to the drawings. The liquid ejection device 11 of the second embodiment includes a foreign matter collection device 90 instead of the mist collection device 60. Therefore, in the second embodiment, instead of the first fan 63 that is the suction source of the mist collection device 60 in the first embodiment, a third fan 92 that is the suction source of the foreign matter collection device 90 is used as an example of a first suction source. The other configurations are basically the same as those of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant explanations will be omitted.

[0102] Hereinafter, with reference to Fig. 11, a device for cooling the drive substrate 50 provided in the liquid ejection device 11 will be described. As shown in Fig. 11, the liquid ejection device 11 includes a foreign matter collection device 90 and an air cooling device 70. The foreign matter collection device 90 is a device that collects foreign matter such as paper dust from the medium 16. The foreign matter collection device 90 includes a first air suction passage 91 and a third fan 92 as an example of a first suction source.

[0103] The third fan 92 generates a suction force capable of sucking air into the first air suction passage 91. The third fan 92 is a foreign matter collection fan that collects foreign matter from the removal section 35. The upstream end of the first air suction passage 91 is connected to the intake port of the third fan 92 via the collection section 93.

[0104] The first air suction passage 61 sucks air at least one of upstream and downstream of the liquid discharger 40 in the direction of relative movement between the medium 16 supported by the support member 45 and the liquid discharger 40, and directs the air downstream in the suction direction Ds. The direction of relative movement is, for example, the conveyance direction D. The first air suction passage 91 sucks air between the support member 45 and the liquid discharger 40 and directs the air downstream in the suction direction Ds. The first air suction passage 91 may be capable of sucking air between the support member 45 and the liquid discharger 40 at a position upstream of the liquid discharger 40 in the conveyance direction D. The first air suction passage 91 particularly collects foreign matter such as paper dust by sucking foreign matter such as paper dust adhering to the removal unit 35. The first air suction passage 91 includes a suction nozzle 94 and a first suction duct 95.

[0105] The suction nozzle section 94 is disposed upstream of the ejection head 41 in the conveyance direction D. The suction nozzle section 94 is disposed at a predetermined position in the width direction X. The suction nozzle section 94 extends diagonally downward toward the removal section 35. The suction nozzle section 94 has a third suction port 94A that opens at its lower end. The third suction port 94A is disposed at a height in the vertical direction Z that allows it to suck in foreign matter, such as paper dust, adhering to the removal section 35. The third suction port 94A is located, for example, above the support surface 45A, which is the upper surface of the support section 45, and below the upper surface of the liquid ejection section 40 in the vertical direction Z. In the example shown in FIG. 11 , the third suction port 94A is located above the nozzle surface, which is the lower surface of the ejection head 41. For example, the third suction port 94A may be located above the ejection head 41.

[0106] The liquid ejection device 11 includes a removal unit 35 that removes foreign matter from the medium 16. The removal unit 35 has a charge removal brush that can contact the support surface 45A of the conveyor belt 46. The charge removal brush has a predetermined length that spans the conveyor belt 46 in the width direction X. The charge removal brush is provided over an area slightly wider than the maximum width of the medium 16. The removal unit 35 removes foreign matter such as paper dust from the surface of the medium 16 using the charge removal brush that contacts the entire surface of the medium 16. The charge removal brush may be configured to be movable in the width direction X.

[0107] The static elimination brush may be formed of a long, flexible member wound around a pair of pulleys located on both sides of the width direction X of the conveyor belt 46. The long static elimination brush may be configured to be able to move back and forth in the width direction X while maintaining contact with the surface of the medium 16 on the conveyor belt 46 by rotating at least one of the pulleys with the power of a motor (not shown). Alternatively, instead of moving back and forth in the width direction X, the static elimination brush may be configured to move in one direction in the width direction X by rotating along a circulation path.

[0108] The liquid ejection device 11 is equipped with a cleaning unit (not shown) that scrapes foreign matter such as paper dust from the moving static elimination brush. The cleaning unit is provided, for example, at one location within the moving range of the static elimination brush in the width direction X. Foreign matter such as paper dust removed by the static elimination brush from the medium 16 adheres to the static elimination brush. The cleaning unit can come into contact with the static elimination brush at a predetermined position in the width direction X. The cleaning unit scrapes foreign matter such as paper dust from the static elimination brush by coming into contact with the static elimination brush as it moves. The foreign matter such as paper dust that has adhered to the static elimination brush is collected at the cleaning position of the cleaning unit.

[0109] The third suction port 94A of the foreign matter collection device 90 is oriented toward the cleaning position. The foreign matter collection device 90 collects foreign matter such as paper dust scraped up by the cleaning unit by sucking it through the third suction port 94A. The first suction duct 95 extends from the first chamber 19A across the partition plate 12F to the second chamber 19B. The downstream end of the first suction duct 95 is connected to a collector 93 disposed in the second chamber 19B. The collector 93 collects foreign matter such as paper dust contained in the air sucked through the first air suction passage 91. The collector 93 has a filter 93F inside.

[0110] The third fan 92 is connected to the collection unit 93. The intake port of the third fan 92 communicates with the exhaust port of the collection unit 93. The third fan 92 sucks in air after foreign matter has been removed by the filter 93F of the collection unit 93. The third fan 92 exhausts the sucked air to the bypass passage 97.

[0111] The configurations of the drive substrate 50 and the air-cooling device 70 are the same as those in the first embodiment. The drive substrate 50 is housed in a housing portion 51. The housing portion 51 has an intake port 51A and an exhaust port 51B on both sides in the longitudinal direction (for example, the Y direction) thereof.

[0112] The air-cooling device 70 includes a second air suction passage 71 and a second fan 72, which is an example of a second suction source. The second air suction passage 71 supplies external air to the drive substrate 50. The downstream end of the second air suction passage 71 is connected to the intake port 51A of the housing portion 51 in which the drive substrate 50 is housed. The second air suction passage 71 has a second suction port 71A that draws in air from outside the device main body 12. The air drawn in through the second air suction passage 71 cools the drive substrate 50 in the housing portion 51. The air-cooling device 70 cools the drive substrate 50 by air cooling.

[0113] The bypass passage 97 has a first bypass passage 98 and a second bypass passage 74. The upstream end of the first bypass passage 98 is connected to the exhaust port of the third fan 92. The second bypass passage 74 communicates with the second air suction passage 71. The downstream end of the first bypass passage 98 and the upstream end of the second bypass passage 74 are opposed to each other.

[0114] A switching mechanism 85 is provided between the first bypass passage 98 and the second bypass passage 74. The switching mechanism 85 is configured to be switchable between an open state in which the bypass passage 97 is connected to the second air suction passage 71 and a closed state in which the bypass passage 97 is not connected to the second air suction passage 71. Specifically, the switching mechanism 85 is switchable between an open state in which the downstream end of the first bypass passage 98 is connected to the upstream end of the second bypass passage 74 and a closed state in which the bypass passage 97 is not connected to the second air suction passage 71. The switching mechanism 85 has an opening / closing plate 86 that can move between a closed position and an open position. The basic configuration of the switching mechanism 85 is similar to that of the switching mechanism 80 shown in FIGS. 5 and 6. The switching mechanism 85 shown in FIG. 12 has, as an example, an opening / closing plate 86 that is rotatable about a rotation shaft 87. The switching mechanism 85 is not limited to a rotating type, and may be a sliding type.

[0115] The first bypass passage 98 has a flow velocity acceleration section 99 in a downstream portion in the discharge direction De. That is, the portion of the bypass passage 97 leading to the switching mechanism 85 in the discharge direction De is formed in a tapered shape such that the passage cross-sectional area is smaller downstream than upstream.

[0116] This tapered flow velocity acceleration section 99 also functions as a guide that directs the air flowing into the second air suction passage 71 in the feeding direction Df. The inclination angle of the inner surface of the flow velocity acceleration section 99 guides the air flowing from the first bypass passage 98 into the second air suction passage 71 in a direction along the feeding direction Df. In addition, the second bypass passage 74 and the opening / closing plate 81 in the closed position also guide the air in this directing direction.

[0117] The control details by which the control unit 100 switches the switching mechanism 80 between the closed state and the open state are basically the same as those in the first embodiment. Furthermore, the control details by which the control unit 100 switches the operating speed of the third fan 92 when the switching mechanism 80 is in the open state are also basically the same as those in the first embodiment, except that the control target is changed from the first fan 63 to the third fan 92.

[0118] <Operation of the Second Embodiment> The operation of this embodiment will be described. While the liquid ejection device 11 is powered on, the removal unit 35 removes foreign matter such as paper dust from the medium 16. The paper dust and other foreign matter adhering to the removal unit 35 is collected at the cleaning position by the cleaning unit. The control unit 100 drives the third fan 92 of the foreign matter collection device 90. The paper dust and other foreign matter collected at the cleaning position is sucked by the suction nozzle unit 94 shown in FIG. 11. The air sucked by the suction nozzle unit 94 flows through the first suction duct 95 to the collection unit 93. The paper dust and other foreign matter contained in the air is collected by the collection unit 93.

[0119] 12, when the switching mechanism 85 is in the closed state, the air from which foreign matter has been removed is exhausted from the third fan 92 to the first bypass passage 98. The air that has flowed through the first bypass passage 98 is exhausted into the device body 12 along the surface of the opening / closing plate 81 that is in the closed position.

[0120] During printing, the air-cooling device 70 is driven. The drive substrate 50, which generates heat during printing, is drawn in by the suction force of the air-cooling device 70 and cooled by the air flowing inside the housing section 51. More specifically, when the second fan 72 is driven, air is sucked in from the second suction port 71A and flows inside the housing section 51, thereby cooling the drive substrate 50.

[0121] The control unit 100 also controls switching of the open / close state of the switching mechanism 80 in accordance with parameters related to the heat generation state of the drive substrate 50, such as the detected temperature, medium size, duty value, and printing speed. The control unit 100 switches the open / close state of the switching mechanism 85 to adjust the flow rate of air used to cool the drive substrate 50 in accordance with the heat generation state of the drive substrate 50. Here, an example will be described in which the control unit 100 controls the opening and closing of the switching mechanism 85 based on the detected temperature.

[0122] When the temperature inside the accommodation unit 51 detected by the first detection unit 101 exceeds the temperature threshold, the control unit 100 switches the switching mechanism 85 from the closed state to the open state, as shown in FIG. 13 . Air discharged from the third fan 92 flows into the second air suction passage 71 through the first bypass passage 98. The air that joins in the second air suction passage 71 is sent in the air supply direction Df. The flow rate of air cooling the drive substrate 50 increases, improving the cooling effect of the drive substrate 50. This prevents excessive temperature rise in the drive substrate 50. When the temperature detected by the first detection unit 101 falls below the temperature threshold, the control unit 100 returns the switching mechanism 85 from the open state to the closed state. In this way, the control unit 100 controls the opening and closing of the switching mechanism 85 according to the detected temperature, allowing an appropriate amount of air to flow through the drive substrate 50. This allows the drive substrate 50 to be appropriately cooled.

[0123] On the other hand, when the control unit 100 detects an abnormality in the second fan 72, it stops the second fan 72 and switches the switching mechanism 85 from the closed state to the open state, as shown in Fig. 14. The air discharged from the first fan 63 flows from the first bypass passage 68 into the second air suction passage 71, causing air to flow inside the storage unit 51. Therefore, even if an abnormality occurs in the second fan 72, the drive substrate 50 can be cooled by the air flowing inside the storage unit 51. Therefore, even if an abnormality occurs in the second fan 72, the liquid discharge operation of the liquid discharge unit 40 can be continued, thereby reducing downtime.

[0124] Furthermore, when the switching mechanism 85 is in the open state, the control unit 100 may control the operating speed of the third fan 92 based on at least one parameter selected from the detected temperature, duty cycle, printing speed, and media size. When the switching mechanism 85 is in the open state and the parameter value exceeds the corresponding threshold, the control unit 100 may increase the operating speed of the third fan 92 from the first speed to the second speed. In this case, the flow rate of air flowing through the housing unit 51 increases. Therefore, even if the amount of heat generated by the drive substrate 50 increases due to a parameter value (detected temperature, duty cycle, printing speed, media size, etc.) that exceeds the threshold, the drive substrate 50 is appropriately cooled. The control unit 100 may control the operating speed of the third fan 92 in three or more stages by setting three or more thresholds. The control unit 100 may also control the operating speed of the second fan 72 in multiple stages based on the above parameters.

[0125] <Effects of the second embodiment> According to the third embodiment, in addition to the effects (1-1) to (1-7) of the first embodiment, the following effects are also obtained.

[0126] The effects of this embodiment will be described. (2-1) A removal unit 35 is provided to remove foreign matter from the medium 16. The third fan 92 is a foreign matter collection fan that collects foreign matter from the removal unit 35. This not only allows foreign matter (e.g., medium powder) to be collected from the medium 16, but also allows the air discharged by the foreign matter collection fan to be used to cool the drive substrate 50. This makes it possible to reduce the size of the second fan 72, which is dedicated to cooling the drive substrate. Furthermore, liquid ejection is possible even when the second fan 72 fails, thereby reducing downtime.

[0127] [Third embodiment] Next, a third embodiment of the liquid ejection device will be described with reference to the drawings. The third embodiment differs from the previous embodiments in that the liquid ejection device 11 includes both a mist collection device 60 and a foreign matter collection device 90. Since the other configurations are basically the same as those of the first embodiment, the same components are designated by the same reference numerals and redundant explanations will be omitted.

[0128] As shown in FIG. 15 , the liquid discharger 11 includes a mist collection device 60, a foreign matter collection device 90, and an air cooling device 70. The mist collection device 60 and the air cooling device 70 have the same configurations as those in the first embodiment. The foreign matter collection device 90 has basically the same configuration as that in the second embodiment. The bypass passage 67, which can connect the first fan 63 and the second air suction passage 71, and the switching mechanism 80 have the same configurations as those in the first embodiment. The bypass passage 97, which can connect the third fan 92 and the first air suction passage 91, and the switching mechanism 85 have the same configurations as those in the second embodiment. The third fan 92 and the bypass passage 97 are positioned differently in the vertical direction Z from those in the second embodiment to prevent interference between the two bypass passages 67, 97.

[0129] In the example shown in Fig. 15, the two switching mechanisms 80, 85 are both of a rotation type, but one or both may be changed to a sliding type configuration as shown in Fig. 6. In this embodiment, in order to distinguish between the two switching mechanisms 80, 85, they are also referred to as a first switching mechanism 80 and a second switching mechanism 85.

[0130] The mist collection device 60 has the same configuration as in the first embodiment. That is, the mist collection device 60 includes a first air suction passage 61 and a first fan 63 as an example of a first suction source. The first fan 63 is a mist collection fan that generates suction force when collecting mist generated when the liquid discharger 40 discharges liquid.

[0131] The liquid discharger 11 includes a bypass passage 67 and a switching mechanism 80. The bypass passage 67 is configured to be able to feed air discharged from the first fan 63 to the second air suction passage 71. The switching mechanism 80 is configured to be able to switch the bypass passage 67 between an open state in which the bypass passage 67 is connected to the second air suction passage 71, and a closed state in which the bypass passage 67 is not connected to the second air suction passage 71.

[0132] The liquid ejection device 11 also includes a removal unit 35 that removes foreign matter from the medium 16, and a foreign matter recovery device 90. The removal unit 35 has a configuration basically similar to that of the second embodiment. That is, the removal unit 35 is configured such that a static elimination brush having a length spanning the width direction X of the conveyor belt 46 is movable in the width direction X. The liquid ejection device 11 also includes a cleaning unit (not shown) similar to that of the second embodiment that scrapes off foreign matter such as paper dust from the static elimination brush while it is moving.

[0133] The foreign matter collection device 90 has the same configuration as that of the second embodiment. That is, the foreign matter collection device 90 includes a first air suction passage 91 and a third fan 92 as an example of a first suction source. The third fan 92 is a foreign matter collection fan that collects foreign matter from the removal unit 35.

[0134] The liquid discharger 11 includes a bypass passage 97 and a second switching mechanism 85. The bypass passage 97 is configured to be able to feed air discharged from the third fan 92 to the second air suction passage 71. The switching mechanism 85 is configured to be able to switch the bypass passage 97 between an open state in which the bypass passage 97 is connected to the second air suction passage 71, and a closed state in which the bypass passage 97 is not connected to the second air suction passage 71.

[0135] As described above, this embodiment includes multiple sets (two sets in this example) of first air suction passages 61, 91, fans 63, 92 which are an example of first suction sources, bypass passages 67, 97, and switching mechanisms 80, 85. Two of the multiple switching mechanisms 80, 85 switch between an open state and a closed state in four or three combinations.

[0136] The control by the control unit 100 to switch the switching mechanisms 80, 85 from the closed state to the open state is basically the same as in the first embodiment. Furthermore, the control by the control unit 100 to switch the operating speeds of the first fan 63 and the third fan 92 when at least one of the switching mechanisms 80, 85 is in the open state is also basically the same as in the above-described embodiments.

[0137] <Operation of the Third Embodiment> The operation of this embodiment will be described. The control unit 100 switches the two switching mechanisms 80, 85 between the open state and the closed state in four or three combinations. An example in which the two switching mechanisms 80, 85 are switched in three combinations will be described below. Also, an example in which the parameters for controlling the opening and closing of the switching mechanisms 80, 85 are the detected temperature and the duty value will be described.

[0138] During printing, the air-cooling device 70 is driven. When the second fan 72 is driven, air is sucked in from the second suction port 71A and flows through the second air suction passage 71 into the housing section 51, thereby cooling the drive substrate 50.

[0139] Furthermore, at least during printing, the mist collection device 60 and the foreign matter collection device 90 are driven. At least during printing, the removal unit 35 moves back and forth in the width direction X, and foreign matter such as paper dust adhering to the static elimination brush is scraped up to the cleaning position by the cleaning unit.

[0140] The mist collection device 60 drives the first fan 63 to suck air containing mist through the mist suction section 62. The air from which the mist has been collected by the collection section 64 is discharged from the first fan 63 through a first bypass passage 68.

[0141] The foreign matter collection device 90 operates the third fan 92 to suck foreign matter such as paper dust collected at the cleaning position through the suction nozzle unit 94. After the paper dust and other foreign matter has been collected by the collector 93, the air is discharged from the third fan 92 through the first bypass passage 98.

[0142] When no abnormality occurs in the second fan 72, the control unit 100 controls the opening and closing of the two switching mechanisms 80, 85 depending on whether at least one of the detected temperature and the duty value exceeds the corresponding threshold. In other words, the control unit 100 controls the opening and closing of the two opening and closing plates 81, 86.

[0143] For example, when the detected temperature and the duty value are both below their corresponding thresholds, as shown in FIG. 16, both switching mechanisms 80 and 85 are closed. Therefore, as shown in FIG. 16, air drawn in by the driving of the second fan 72 flows through the accommodation section 51, thereby cooling the drive substrate 50. Meanwhile, air discharged from the first bypass passage 68 is guided along the surface of the opening / closing plate 81 in the closed position and exhausted into the device body 12. Air discharged from the first bypass passage 98 is also guided along the surface of the opening / closing plate 86 in the closed position and exhausted into the device body 12. In other words, the air exhausted by the first fan 63 and the third fan 92 is not used to cool the drive substrate 50.

[0144] When either the detected temperature or the duty value exceeds the corresponding threshold, the control unit 100 switches the switching mechanism 80 from the closed state to the open state, as shown in Fig. 17. Therefore, as shown in Fig. 17, the air sucked in by driving the second fan 72 and the air exhausted by the first fan 63 join together in the second air suction passage 71 and are supplied into the housing unit 51. Since a larger flow rate of air flows through the housing unit 51 than in the case shown in Fig. 16, the drive substrate 50 is appropriately cooled. In this case, the air exhausted by the third fan 92 is not used to cool the drive substrate 50.

[0145] When the detected temperature and the duty value both exceed their corresponding thresholds, the control unit 100 opens both of the two switching mechanisms 80, 85, as shown in Fig. 18. Therefore, as shown in Fig. 18, the air sucked in by driving the second fan 72, the air exhausted by the first fan 63, and the air exhausted by the third fan 92 join together in the second air suction passage 71 and are supplied into the housing unit 51. Therefore, a larger flow rate of air flows through the housing unit 51 than in the case shown in Fig. 17, and the drive substrate 50 is appropriately cooled.

[0146] In the above example, the two switching mechanisms 80, 85 are opened and closed in three combinations, but they may be opened and closed in four combinations. As a combination in which only one of the two switching mechanisms 80, 85 is opened, both a configuration in which only the first switching mechanism 80 is opened and a configuration in which only the second switching mechanism 85 is opened, as shown in FIG. 17 , may be employed. For example, if the exhaust flow rates of the first fan 63 and the third fan 92 are different, the flow rate of air flowing through the storage unit 51 can be varied depending on which of the two switching mechanisms 80, 85 is opened. In such a case, the flow rate of air flowing through the storage unit 51 may be adjusted in four stages by opening and closing the two switching mechanisms 80, 85 in four combinations.

[0147] On the other hand, if an abnormality in the second fan 72 is detected, the control unit 100 switches the two switching mechanisms 80, 85 from the closed state to the open state, as shown in FIG. 19 . That is, the control unit 100 places the respective opening / closing plates 81, 86 of the two switching mechanisms 80, 85 in the open position. Air discharged from the first fan 63 flows from the first bypass passage 68 into the second air suction passage 71. Air discharged from the third fan 92 also flows from the first bypass passage 98 into the second air suction passage 71. Therefore, air discharged from the two fans 63, 92 flows through the housing unit 51. Therefore, even if an abnormality occurs in the second fan 72, sufficient air flows through the housing unit 51, allowing the drive substrate 50 to be appropriately cooled. Therefore, even if an abnormality occurs in the second fan 72, the liquid discharger 40 can still perform its liquid discharge operation. This reduces downtime.

[0148] Furthermore, when at least one of the two switching mechanisms 80, 85 is in an open state, the control unit 100 may control the operating speed of the fan corresponding to the open switching mechanism. That is, when at least one parameter among the detected temperature, duty value, printing speed, and medium size exceeds the corresponding threshold, the control unit 100 may increase the operating speed of at least one of the fans 63, 92 from a first speed to a second speed. By setting three or more thresholds, the control unit 100 may control the operating speeds of the fans 63, 92 in three or more combinations. Furthermore, the control unit 100 may control the operating speed of the second fan 72 in multiple stages based on the above parameters.

[0149] <Effects of the third embodiment> According to the third embodiment, in addition to the effects (1-1) to (1-7) of the first embodiment and the effect (2-1) of the second embodiment, the following effects are also obtained.

[0150] (3-1) The cooling fan 72 includes multiple sets (for example, two sets) of first air suction passages 61, 91, fans 63, 92, bypass passages 67, 97, and switching mechanisms 80, 85. Two of the multiple sets of switching mechanisms 80, 85 switch between an open state and a closed state in four or three combinations. This makes it easier to further miniaturize the second fan 72 dedicated to cooling the drive substrate.

[0151] [Example of change] This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0152] As shown in FIG. 20, the rotation type switching mechanism 80 may have a rotation shaft 82 at the downstream end of the first bypass passage 68. 21, the sliding type switching mechanism 80 may be configured such that an opening / closing plate 81 moves vertically. Also, the bypass passage 67 may be configured only with the first bypass passage 68. The second air suction passage 71 may be configured such that it has only an opening that is opened and closed by the opening / closing plate 81 at a position opposite the downstream end of the first bypass passage 68.

[0153] As shown in Fig. 22, the sliding type switching mechanism 80 may be configured such that the opening / closing plate 81 is opened by moving downward, unlike the opening / closing plate 81 shown in Fig. 6. Also, the tilt direction of the sliding opening / closing plate 81 relative to the horizontal plane may be opposite to that shown in Fig. 6.

[0154] As shown in FIG. 23 , if the switching mechanism 80 is a first switching mechanism 80, a third switching mechanism 120 that opens and closes the suction port 71A of the second air suction passage 71 may be provided in addition to the first switching mechanism 80. The third switching mechanism 120 has an opening / closing plate 121 that is rotatable about a rotation shaft 122. When the opening / closing plate 81 of the first switching mechanism 80 is in the closed position, the opening / closing plate 121 of the third switching mechanism 120 is in the open position indicated by the two-dot chain line in FIG. 23 . Furthermore, when the opening / closing plate 81 of the first switching mechanism 80 is in the open position, the opening / closing plate 121 of the third switching mechanism 120 is in the closed position indicated by the solid line in FIG. 23 . With this configuration, when the switching mechanism 80 is in the closed state, the second air suction passage 71 can draw air through the second suction port 71A. Furthermore, when the switching mechanism 80 is in the open state, the air that has flowed from the first bypass passage 68 into the second air suction passage 71 is less likely to leak from the second suction port 71A. Therefore, the air from the first bypass passage 68 can be used efficiently to cool the drive substrate 50.

[0155] The position of the switching mechanism 80 may be closer to the first fan 63 in the bypass passage 67 instead of closer to the first air suction passage 61 . If the switching mechanism is of a rotation type, the rotation axis is not limited to an axis parallel to the X axis, but may be an axis parallel to the Y axis or the Z axis. Also, if the switching mechanism is of a sliding type, the sliding direction is not limited to a direction parallel to the YZ plane, but may be a direction parallel to the XY plane or the XZ plane.

[0156] The switching mechanism 80 may be of a type other than a rotating type or a sliding type. For example, a rotating type and a sliding type may be combined. Also, multiple opening / closing plates 81 may be combined. In this case, multiple opening / closing plates 81 of the same type may be combined, or multiple opening / closing plates 81 of different types may be combined. Furthermore, when the switching mechanism is in the open state, the bypass passage 67 may be configured to communicate only with the second air suction passage 71 and not with the outside.

[0157] The electronic circuit mounting board cooled by the second fan 72 may be an electronic circuit mounting board other than the drive board 50 that outputs drive signals to the liquid discharger 40. For example, it may be an electronic circuit mounting board that constitutes the control unit 100. It may also be an electronic circuit mounting board in which the electronic circuits that constitute the control unit 100 and the discharge control unit 52 are mounted on the same circuit board such as a motherboard. The electronic circuit mounting board may also be a power supply board.

[0158] In the third embodiment, when there are three combinations of open and closed states of the two switching mechanisms 80, 85, if only one of them is to be in the open state, the second switching mechanism 85 may be in the open state. In the third embodiment, the switching mechanisms 80, 85 may be controlled to switch based on a single parameter. For example, two or three thresholds may be set, and the number or combination of the switching mechanisms 80, 85 to be opened may be changed each time the parameter value exceeds the threshold. The parameter may be one of the detected temperature, duty value, print speed, and medium size.

[0159] In the first and second embodiments, the switching mechanism may be controlled based on multiple parameters. The control unit 100 may switch the switching mechanism from the closed state to the closed state when any one of the multiple parameters exceeds a corresponding threshold. The parameters may be two or more of the detected temperature, duty value, print speed, and medium size.

[0160] In the second and third embodiments, the removal unit 35 does not need to have a movable anti-static brush. In this case, the cleaning unit does not need to be provided. The foreign matter collection device 90 may be configured to have a third suction port 94A that extends across the entire width of the medium 16.

[0161] The switching mechanisms 80, 85 may be flow path switching valves. The flow path switching valves are connected, for example, to the downstream end of the first bypass passage 68 and switch the destination of the air discharge between an exhaust flow path leading to the device main body 12 and an inflow flow path communicating with the second air suction passage 71. A flow path switching valve can switch the destination of the air discharge while suppressing air leakage. The flow path switching valves may also have a flow rate adjustment function that can adjust the flow rate ratio for each flow path. In this case, the control unit 100 may switch the switching mechanism and adjust the amount of inflow air based on the result of comparing a parameter value with a threshold value based on a parameter.

[0162] The paths and extending directions of the first air suction passages 61, 91 and the second air suction passage 71 may be changed as appropriate. The liquid ejection device 11 may be a textile printing device that ejects liquid onto fabric, which is an example of the medium 16. In this case, the foreign matter recovery device 90 may be a device that recovers fluff from the fabric.

[0163] In the above embodiments, the device having the first air suction passage and the first suction source is the mist collection device 60 and the foreign matter collection device 90, but it may be another collection device or another air suction device. For example, it may be a collection device that collects objects other than mist or paper dust, or an air suction device that sucks air to form an air flow.

[0164] The liquid ejector 11 may be a serial printer. For example, the first air suction passage 61, 91 may be configured to suck air at least one of upstream and downstream positions of the liquid ejector 40 in the direction of relative movement between the medium 16 supported by the support member 45 and the liquid ejector 40, and to direct the air downstream in the suction direction Dm, Ds. In the case of a serial printer, the direction of relative movement may be the transport direction D or the movement direction (scanning direction) of a carriage carrying the liquid ejector 40. For example, the first air suction passage 61, 91 may suck air at least one of upstream and downstream positions in the transport direction D that sandwich the scanning path of the liquid ejector 40. Alternatively, for example, the first air suction passage 61, 91 may suck air at least one of upstream and downstream positions in the scanning direction, which is the direction of relative movement between the liquid ejector 40 moving in the scanning direction and the medium 16. In this case, at least one of the suction nozzle units 66, 94 may be fixed to the carriage.

[0165] The drive substrate 50 may be built into the liquid discharger 40. In this case, a second air suction passage 71 may be connected to the liquid discharger 40 so that air can be supplied into the liquid discharger 40. In this case, the housing of the liquid discharger 40 may serve as a housing, and a second fan 72, which is an example of a second suction source, may be fixed to the liquid discharger 40 so that it can suck air from inside the housing. Also, a second air suction passage 71 may be fixed to the liquid discharger 40, which directs air along the outer surface of the portion of the liquid discharger 40 in which the drive substrate 50 is built or along cooling fins provided on the outer surface. In this case, the second air suction passage 71 also serves as a flow path for air to cool the cooled surface or fins, and the second fan 72 is connected to the downstream end of the second air suction passage 71. Also, a housing 51 that houses the drive substrate 50 may be disposed within the liquid discharger 40, and air may be supplied into the housing from the second air suction passage 71. In these configurations, at least one of two pairs of a first air suction passage 61, 91 and a first fan 63, 92, which is an example of a first suction source, may be provided, and at least one of two pairs of a bypass passage 67, 97 and a switching mechanism 80, 85 may be provided.

[0166] The suction ports of the first air suction passages 61, 91 do not have to face the liquid discharger 40. For example, the third suction port 94A may face upstream instead of downstream in the conveyance direction D, as long as it can suck in foreign matter such as paper dust. In other words, the suction ports 62A, 94A of the first air suction passages 61, 91 are not limited to positions and orientations that allow them to suck in air between the liquid discharger 40 and the support member 45. The orientation of the suction port may be set as appropriate, as long as it can suck in air at least at a position upstream or downstream of the liquid discharger 40 in the direction of relative movement between the liquid discharger 40 and the medium 16.

[0167] The support 45 may be a platform that supports the transported medium 16. The support 45 may be, for example, a platen. The liquid ejection device 11 may be a liquid ejection device that ejects liquids other than ink. The liquid ejected as minute droplets from the liquid ejection device may be in the form of granules, tears, or strings. The liquid referred to here may be any material that can be ejected from the liquid ejection device. For example, the liquid may be in any liquid phase, including fluids such as high or low viscosity liquids, sols, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals, and metal melts. The liquid may refer not only to a single state of matter, but also to particles of functional materials, such as solid pigments and metal particles, dissolved, dispersed, or mixed in a solvent. Typical examples of liquids include inks and liquid crystals, as described in the above embodiments. Here, ink encompasses various liquid compositions, such as general water-based inks and oil-based inks, as well as gel inks and hot-melt inks. Specific examples of liquid ejection devices include devices that eject liquids containing dispersed or dissolved materials such as electrode materials and color materials used in the manufacture of liquid crystal displays, electroluminescent displays, surface-emitting displays, and color filters. The liquid ejection device may be a device that ejects bioorganic materials used in biochip manufacture, a device used as a precision pipette to eject sample liquids, a textile printing device, a microdispenser, or the like. The liquid ejection device may be a device that ejects lubricating oil with pinpoint accuracy onto precision machinery such as watches and cameras, or a device that ejects transparent resin liquids such as ultraviolet-curing resins onto substrates to form micro-hemispherical lenses, optical lenses, and the like used in optical communication elements. The liquid ejection device may also be a device that ejects etching liquids such as acids or alkalis to etch substrates, etc.

[0168] [Definition] The phrase "at least one" as used herein means "one or more" of the desired options. As an example, the phrase "at least one" as used herein means "only one option" or "both of two options" when the number of options is two. As another example, the phrase "at least one" as used herein means "only one option," "any combination of two options," or "any combination of three or more options" when the number of options is three or more.

[0169] [Note] The technical concepts and effects that can be understood from the above-described embodiment and modified examples will be described below.

[0170] (A) A liquid ejection device includes a liquid ejection unit that ejects liquid onto a medium, a support unit that supports the medium at a position opposite the liquid ejection unit, an electronic circuit mounting board, a first air suction passage that sucks air at a position upstream or downstream of the liquid ejection unit in the relative movement direction between the medium supported by the support unit and the liquid ejection unit and flows it downstream in the suction direction, a first suction source that generates a suction force capable of sucking air into the first air suction passage, a second air suction passage that supplies external air to the electronic circuit mounting board, a second suction source that generates an air flow in the second air suction passage in a supply direction toward the electronic circuit mounting board, a bypass passage configured to supply air discharged from the first suction source to the second air suction passage, and a switching mechanism configured to switch the bypass passage between an open state that connects the bypass passage to the second air suction passage and a closed state that does not connect the bypass passage to the second air suction passage.

[0171] According to the above configuration, by switching the switching mechanism from the closed state to the open state, the air discharged by the first suction source can be used to cool the electronic circuit mounting board. This reduces downtime caused by an abnormality in the second suction source, and also reduces the need for an increased capacity for the second suction source. Therefore, even if the flow rate of cooling air is insufficient due to an abnormality or capacity limit of the suction source dedicated to board cooling, the electronic circuit mounting board can be adequately cooled.

[0172] (B) In the liquid ejection device described above in (A), when the liquid ejection unit performs a liquid ejection operation while an abnormality occurs in the second suction source, the second suction source may be stopped and the switching mechanism may be set to the open state.

[0173] According to the above configuration, it is possible to prevent downtime caused by an abnormality in the second suction source, which makes it impossible to perform the liquid ejection operation. (C) The liquid ejection device according to (A) or (B) above may further include a storage unit for storing the electronic circuit board and a detection unit for detecting the temperature inside the storage unit, and the switching mechanism may be set to the open state when the temperature detected by the detection unit exceeds a temperature threshold. With this configuration, the time required to lower the temperature inside the storage unit to a target temperature can be shortened by using air blown by the first suction source.

[0174] (D) In ​​the liquid ejection device described in any one of (A) to (C) above, the first suction source may be a mist collection fan that generates a suction force to collect mist generated when the liquid ejection section ejects liquid.

[0175] This configuration not only allows the mist generated when the liquid discharger discharges liquid to be collected, but also allows the air discharged by the mist collection fan to be used to cool the electronic circuit board, making it possible to reduce the size of the second suction source and continue discharging liquid even when the second suction source fails.

[0176] (E) In the liquid ejection device described in any one of (A) to (D) above, a removal section that removes foreign matter from the medium may be provided, and the first suction source may be a foreign matter recovery fan that recovers foreign matter from the removal section.

[0177] This configuration not only allows foreign matter (e.g., medium powder) to be collected from the medium, but also allows the air discharged by the foreign matter collection fan to be used to cool the electronic circuit mounting board, making it possible to reduce the size of the second suction source and continue discharging liquid even if the second suction source fails.

[0178] (F) In the liquid ejection device described in any one of (C) to (E) above, when the switching mechanism is in the open state, the first suction source may be driven at a higher operating speed when the temperature detected by the detection unit is a second temperature higher than the first temperature than when the temperature is a first temperature.

[0179] According to the above configuration, when the switching mechanism is in the open state, the first suction source is driven at an operating speed according to the detected temperature inside the accommodation unit, so that air can be supplied to the electronic circuit board at a flow rate appropriate for cooling.

[0180] (G) In the liquid discharge device described in any one of (A) to (F) above, the liquid discharge device may include a plurality of sets of the first air suction passage, the first suction source, the bypass passage, and the switching mechanism, and two of the plurality of the switching mechanisms may switch between the open state and the closed state in four or three combinations. This configuration makes it easier to further miniaturize the second suction source for cooling the electronic circuit board.

[0181] (H) In the liquid discharge device described in any one of (A) to (G) above, the portion of the bypass passage leading to the switching mechanism in the air discharge direction may be formed in a tapered shape such that the cross-sectional area of ​​the passage is smaller downstream than upstream. With this configuration, when the switching mechanism is in the open position, it is possible to suppress a decrease in the flow rate of air flowing from the bypass passage into the second air suction passage.

[0182] (I) In the liquid ejection device described in any one of (A) to (H) above, the switching mechanism may have an opening / closing plate, and the opening / closing plate may be of a rotating type or a sliding type. According to the above configuration, the air flows can be easily switched between merging and non-merging with a simple configuration by rotating or sliding the opening / closing plate. [Explanation of symbols]

[0183] 11...liquid ejection device, 12...device main body, 12A to 12D...side panels, 12F...partition plate, 13...image reading device, 14...automatic feeder, 15...operation unit, 16...medium, 17...medium storage unit, 18...stacker, 19A...first chamber, 19B...second chamber, 20...conveying unit, 20M...conveying motor, 21...conveying path, 22...feeding path, 23...feeding path, 24...discharge path, 26...feeding unit, 29...feeding roller, 30...separating unit, 31...roller pair, 32...registration roller, 33...charging unit, 34...ground roller, 35...removing unit, 36...discharge unit, 40...liquid discharge unit, 41...discharge head, 45...support unit, 45A...support surface, 46...conveyor belt, 47...drive pulley, 48...followed pulley, 49...pair of conveyor rollers, 50...drive board which is an example of an electronic circuit mounting board, 51...accommodation unit, 51A...intake port, 51B...exhaust port, 52...discharge control unit, 60...mist collection device, 61...first air suction passage, 62...mist suction unit, 62A...first suction port, 63...first fan which is an example of a first suction source, 64...collection unit, 64F...filter, 65...first suction duct, 66...suction nozzle portion, 67...bypass passage, 68...first bypass passage, 69...flow velocity acceleration portion, 70...air cooling device, 71...second air suction passage, 71A...second suction port, 72...second fan which is an example of the second suction source, 72A...exhaust port, 73...second bypass passage, 73A...guide plate portion, 74...second bypass passage, 80...switching mechanism (first switching mechanism), 81...opening / closing plate, 82...rotating shaft, 83...actuator, 84...power transmission portion, 85...switching mechanism (second switching mechanism), 86...opening / closing plate, 90...foreign matter collection device, 91...first air suction passage, 92...third fan , 93...collection section, 93F...filter, 94...suction nozzle section, 94A...third suction port, 95...first suction duct, 97...bypass passage, 98...first bypass passage, 99...flow rate acceleration section, 100...control section, 101...first detection section, 102...second detection section, 111...conveyance control section, 112...printing speed acquisition section, 113...abnormality detection section, 120...third switching mechanism, 121...opening / closing plate, 122...rotating shaft, D...conveyance direction, De...discharge direction, Df...feed direction, Dm...suction direction, Ds...suction direction, PD...print data, X...width direction, Z...vertical direction.

Claims

1. a liquid ejection unit that ejects liquid onto a medium; a support portion that supports the medium at a position facing the liquid ejection portion; an electronic circuit mounting board; a first air suction passage that sucks air at a position upstream or downstream of the liquid discharger in a relative movement direction between the medium supported by the support section and the liquid discharger, and flows the air downstream in the suction direction; a first suction source that generates a suction force capable of sucking air into the first air suction passage; a second air suction passage for supplying external air to the electronic circuit mounting board; a second suction source that generates an air flow in the second air suction passage in a feeding direction toward the electronic circuit mounting board; a bypass passage configured to supply air discharged from the first suction source to the second air suction passage; a switching mechanism configured to switch the bypass passage between an open state in which the bypass passage is connected to the second air suction passage and a closed state in which the bypass passage is not connected to the second air suction passage; A liquid ejection device comprising:

2. When the liquid discharger performs a liquid discharge operation in a state where an abnormality occurs in the second suction source, deactivating the second suction source; The liquid ejection device according to claim 1 , wherein the switching mechanism is in the open state.

3. a housing portion in which the electronic circuit mounting board is housed; a detection unit that detects the temperature inside the storage unit, The liquid ejection device according to claim 1 , wherein the switching mechanism is set to the open state when the temperature detected by the detection unit exceeds a temperature threshold value.

4. 2. The liquid ejection device according to claim 1, wherein the first suction source is a mist collection fan that generates a suction force for collecting mist that is generated when the liquid ejection unit ejects liquid.

5. a removal unit that removes foreign matter from the medium; 2. The liquid ejection device according to claim 1, wherein the first suction source is a foreign matter recovery fan that recovers foreign matter from the removal unit.

6. The liquid ejection device according to claim 3, characterized in that, when the switching mechanism is in the open state, the first suction source is driven at a higher operating speed when the temperature detected by the detection unit is a second temperature higher than the first temperature than when the temperature is a first temperature.

7. a plurality of sets of the first air suction passage, the first suction source, the bypass passage, and the switching mechanism; The liquid ejection device according to claim 3 , wherein two of the plurality of switching mechanisms switch between the open state and the closed state in four or three combinations.

8. 2. The liquid ejection device according to claim 1, wherein a portion of the bypass passage leading to the switching mechanism in the air discharge direction is formed in a tapered shape such that the cross-sectional area of ​​the passage is smaller downstream than upstream.

9. The switching mechanism has an opening / closing plate, 2. The liquid ejection device according to claim 1, wherein the opening and closing plate is of a rotating type or a sliding type.

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