Control method of liquid discharge device and liquid discharge device

Abstract

To provide a control method of a liquid discharge device and the liquid discharge device which can suppress an amount of a liquid uselessly discharged from nozzles by idle discharge.SOLUTION: A liquid discharge device includes a liquid discharge part, a pressurization part, a wiping part and a detection part. The pressurization part swells a liquid from a plurality of nozzles by pressurization. The detection part detects the nozzle with which droplets attached to a nozzle surface are brought into contact. A control method of the liquid discharge device includes the following (a) to (e): (a) swelling the liquid from a plurality of nozzle groups by pressurization of the pressurization part (S12); (b) wiping the nozzle surface by the wiping part (S13) and performing detection by the detection part (S14), in a state in which the operation in pressurization is maintained; (c) setting idle discharge amounts of each of the plurality of nozzles (S17), on the basis of the detection result of the detection part; (d) releasing the pressurization of the pressurization part (S15); and (e) performing idle discharge from the plurality of nozzles with the set idle discharge amount (S18).SELECTED DRAWING: Figure 28

Description

[Technical field]

[0001] The present invention relates to a control method for a liquid ejection device having a liquid ejection section that ejects liquid, and to a liquid ejection device. [Background technology]

[0002] Patent Document 1 discloses a liquid ejection device including a head unit (an example of a liquid ejection section) that ejects liquid. This liquid ejection device includes a liquid container that contains liquid, a liquid ejection head that ejects liquid, and a supply flow path that supplies liquid from the liquid container to the liquid ejection head. In addition, in order to expel ink of other colors that has been drawn from the nozzles by wiping or the like, a flushing operation is performed in which ink is ejected from all the nozzles of the head unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-14264 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, because blank discharge (flushing) is performed uniformly from all nozzles to prevent color mixing, it is not possible to set the blank discharge amount according to the state of each nozzle, and the amount of liquid such as ink that is wasted from the nozzles increases. For this reason, there is a problem of wanting to reduce the amount of liquid that is wasted from the nozzles due to blank discharge. Note that this problem is not limited to liquid discharge devices such as printers that discharge ink, but also exists in liquid discharge devices that discharge liquids other than ink. [Means for solving the problem]

[0005] A control method for a liquid ejection device that solves the above problem is a control method for a liquid ejection device that includes a liquid ejection unit capable of recording by ejecting liquid from a plurality of nozzle groups formed on a nozzle surface, a pressurization unit capable of pressurizing the liquid in the plurality of nozzle groups to cause the liquid to swell from the plurality of nozzle groups, a wiping unit capable of wiping the nozzle surface, and a detection unit capable of detecting nozzles with which droplets adhering to the nozzle surface come into contact, the control method including: causing the liquid to swell from the plurality of nozzle groups by the pressurization of the pressurization unit; wiping the nozzle surface by the wiping unit and detection by the detection unit while maintaining the operation of the pressurization of the pressurization unit; setting an amount of blank ejection for each of the plurality of nozzles that constitute the plurality of nozzle groups based on the detection result by the detection unit; releasing the pressurization of the pressurization unit; and performing blank ejection, which is the ejection of liquid unrelated to the recording, from the plurality of nozzles based on the set amount of blank ejection.

[0006] A liquid ejection device that solves the above problem includes a liquid ejection unit capable of recording by ejecting liquid from multiple nozzle groups formed on a nozzle surface, a pressurization unit capable of pressurizing the liquid in the multiple nozzle groups to cause the liquid to swell from the multiple nozzle groups, a wiping unit capable of wiping the nozzle surface, a detection unit capable of detecting nozzles in contact with droplets adhering to the nozzle surface, and a control unit, wherein the control unit causes the liquid to swell from the multiple nozzle groups by applying pressure from the pressurization unit, wipes the nozzle surface with the wiping unit and performs detection with the detection unit while maintaining the operation of the pressurization unit, sets an amount of blank ejection for each of the multiple nozzles that constitute the multiple nozzle groups based on the detection results by the detection unit, releases the pressurization of the pressurization unit, and performs blank ejection, which is the ejection of liquid unrelated to the recording, from the multiple nozzles based on the set amount of blank ejection. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a liquid ejection device according to an embodiment. [Diagram 2]FIG. 2 is a schematic front cross-sectional view showing the internal configuration of the liquid ejection device. [Diagram 3] FIG. 3 is a schematic diagram showing the liquid ejection mechanism and the maintenance unit. [Figure 4] FIG. 4 is a bottom view of the liquid ejection head. [Diagram 5] FIG. 5 is a schematic bottom view showing the nozzle arrangement of the liquid ejection head and the wiping portion. [Figure 6] FIG. 6 is a schematic front view, partly cut away, showing the pressurizing portion when the on-off valve is closed. [Figure 7] FIG. 7 is a schematic front view, partly cut away, showing the pressure applying portion in the pressure applying position. [Figure 8] FIG. 8 is a schematic front view, partly cut away, showing the pressurizing unit in the pressurizing position with the on-off valve open. [Figure 9] FIG. 9 is a schematic front view, partly cut away, showing the pressurizing unit with the on-off valve in the pressure release position. [Figure 10] FIG. 10 is a schematic cross-sectional view showing the state of liquid in a nozzle during printing. [Figure 11] FIG. 11 is a schematic cross-sectional view showing liquid expanding from a nozzle when pressurized. [Figure 12] FIG. 12 is a schematic cross-sectional view showing the liquid in the nozzle during wiping. [Figure 13] FIG. 13 is a schematic cross-sectional view showing the liquid in the nozzle when the pressure is released. [Figure 14] FIG. 14 is a schematic cross-sectional view showing the state of the mixed liquid remaining on the nozzle surface after wiping. [Figure 15] FIG. 15 is a schematic cross-sectional view showing a state in which the mixed color liquid is sucked into the nozzle. [Figure 16] FIG. 16 is a cross-sectional view showing the configuration of the ejection section. [Figure 17] FIG. 17 is a block diagram showing the electrical configuration of the liquid ejection device. [Figure 18] FIG. 18 is a block diagram showing an electrical configuration related to ejection abnormality detection. [Figure 19]FIG. 19 is a circuit diagram showing an equivalent circuit related to ejection abnormality detection. [Figure 20] FIG. 20 is a graph showing the relationship between the residual vibration signal and the ejection abnormality. [Figure 21] FIG. 21 is a graph showing the detection results of the nozzle inspection unit after wiping. [Figure 22] FIG. 22 is a schematic cross-sectional view of the liquid ejection head showing the first nozzle that is the target of the first blank ejection in the first embodiment. [Diagram 23] FIG. 23 is a schematic cross-sectional view of the liquid ejection head, showing the first nozzle that is the target of the first blank ejection. [Figure 24] FIG. 24 is a schematic cross-sectional view of a liquid ejection head showing a first nozzle that is a target of the first blank ejection in the second embodiment. [Diagram 25] FIG. 25 is a schematic cross-sectional view of the liquid ejection head, showing the first nozzle that is the target of the first blank ejection. [Figure 26] FIG. 26 is a schematic cross-sectional view of a liquid ejection head showing a first nozzle that is a target of the first blank ejection in the third embodiment. [Figure 27] FIG. 27 is a schematic cross-sectional view of the liquid ejection head, showing the first nozzle that is the target of the first blank ejection. [Figure 28] FIG. 28 is a flowchart showing the maintenance control routine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A liquid ejection device and a control method thereof according to an embodiment 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 M such as paper to record. In Fig. 1, the liquid ejection device 11 is placed on a horizontal plane, and the direction of gravity is indicated by the Z axis, and the directions along the horizontal plane are indicated by the X axis and the Y axis. The X axis, the Y axis, and the Z axis are perpendicular to each other.

[0009] As shown in FIG. 1, the liquid ejection device 11 may include a device main body 12, an image reading unit 13 that reads an image of a document, and an automatic feeder 14 that sends the document to the image reading unit 13. The liquid ejection device 11 may include an operation unit 15 that is operated by a user to give instructions to the liquid ejection device 11, a medium storage unit 16 that can store a medium M such as paper, and a stacker 17 that receives the medium M discharged after printing. The operation unit 15 may be, for example, a touch panel or a button, or a combination of these. The medium storage unit 16 can store multiple media M in a stacked state. The liquid ejection device 11 may include multiple medium storage units 16.

[0010] Next, the internal configuration of the liquid ejection device 11 will be described with reference to Fig. 2. As shown in Fig. 2, the device main body 12 has a housing 18 having a substantially rectangular parallelepiped shape. The liquid ejection device 11 includes, within the housing 18, a liquid ejection unit 20, a transport unit 30 that transports the medium M, a maintenance unit 40 that performs maintenance on the liquid ejection head 22, and a control unit 100 that controls the components including these.

[0011] The liquid ejection section 20 includes a liquid ejection head 22 having a plurality of nozzles 21 capable of ejecting liquid droplets, and a support section 23 that holds the liquid ejection head 22 at a predetermined height. The plurality of nozzles 21 are opened in a nozzle surface 28, which is a surface (e.g., a bottom surface) of the liquid ejection head 22 that faces a transport path along which the medium M is transported.

[0012] The liquid ejection head 22 ejects liquid onto the medium M. If the position at which the liquid ejection head 22 ejects liquid is defined as a recording position, then printing is performed by ejecting liquid from the nozzles 21 toward the medium M at the recording position. The liquid ejection head 22 of this embodiment is a line head having a plurality of nozzles 21 capable of simultaneously ejecting liquid across the entire width of the medium M in the width direction X that intersects (orthogonal in this embodiment) the transport direction Y and the ejection direction Z. The liquid ejection device 11 performs line printing by ejecting liquid from the plurality of nozzles 21 located at positions facing the entire width of the medium M, which is transported at a constant speed corresponding to the print mode.

[0013] The liquid ejection head 22 is supported by a support portion 23 in a state extending in a width direction X intersecting with a transport direction Y of the medium M. The liquid ejection head 22 is configured to eject liquid onto the medium M from a plurality of nozzles 21 constituting a plurality of nozzle groups. A supply flow path 25 for supplying liquid from a liquid container 24 is connected to the liquid ejection head 22. A plurality of liquid containers 24 are attached to a holder 26 in the housing 18.

[0014] The liquid containers 24 each contain a different type of liquid. In an example where the liquid is ink, the liquid containers 24 each contain ink of a different color. In this example, the liquid containers 24 each contain black ink and color ink. The liquid containers 24 each contain black, yellow, cyan, and magenta ink. That is, the liquid containers 24 are a black liquid container 24K, a yellow liquid container 24Y, a cyan liquid container 24C, and a magenta liquid container 24M. Since the black liquid container 24K consumes a large amount of ink, a plurality of the black liquid containers 24K (for example, two) may be attached as in the example shown in FIG. 2, and the black liquid container 24K may have a larger volume than the other ink colors. The number of the liquid containers 24 is not limited to the five in the example shown in FIG. 2, and may be changed appropriately according to the number of ink colors, and may be 6 to 10, or 1 to 4.

[0015] The liquid container 24 is, for example, a liquid cartridge that is detachably attached to the holder 26, but may also be a liquid tank. In the case of a liquid tank, the liquid may be replenished by a user pouring liquid from a container such as a bottle.

[0016] The transport unit 30 includes a feed roller 31 that feeds the media M one by one from the group of media M stacked in the medium storage unit 16, starting from the top one, and a separation roller 32 that separates the media M one by one. The transport unit 30 further includes a plurality of transport rollers 33 that transport the media M along a transport path that is a path that passes through the recording position, and a transport belt 34 that transports the media M at the recording position. The transport belt 34 is wound around a first roller 35 and a second roller 36.

[0017] The conveyor belt 34 is configured to be rotatable about the first roller 35. The conveyor belt 34 is moved by a support portion moving mechanism 37 between a support position shown by a solid line in FIG. 2 and a retracted position shown by a two-dot chain line in FIG. 2. At the support position, the conveyor belt 34 supports the medium M being conveyed. That is, the conveyor belt 34 has the function of a support portion that supports the medium M so as to keep a constant gap between the medium M being conveyed and the liquid ejection head 22. Here, the conveying direction Y refers to the conveying direction of the medium M at the recording position.

[0018] The medium storage unit 16 is, for example, a cassette, and is removably inserted into a recess (not shown) formed in the housing 18. In the inserted state shown in Fig. 2, the medium M stored in the medium storage unit 16 is located inside the housing 18. Note that Fig. 2 shows only the topmost one of the multiple medium storage units 16, and the others are omitted.

[0019] The medium container 16 includes a movable edge guide 16A that is operated by a user. The medium M in the medium container 16 is positioned in the width direction by the edge guide 16A. The liquid ejection device 11 may include a size detection unit 19 shown in FIG. 2 that detects the size of the medium M contained in the medium container 16.

[0020] The liquid ejection device 11 includes a waste liquid container 50 that contains waste liquid generated during maintenance of the liquid ejection head 22. The waste liquid container 50 is detachably attached to a holder 51. The waste liquid container 50 attached to the holder 51 is disposed at a predetermined position within the housing 18.

[0021] The maintenance unit 40 performs maintenance operations such as blank ejection and cleaning in the liquid ejection head 22 to prevent or resolve ejection defects caused by clogging of the nozzles 21 or adhesion of foreign matter.

[0022] The maintenance unit 40 includes a plurality of caps 41 configured to cover a plurality of nozzle groups, a discharge mechanism 44 that discharges liquid from within the caps 41, and a cap moving mechanism 45 that moves the caps 41. The discharge mechanism 44 includes a waste liquid flow path 42 that connects the caps 41 and the holder 51, and a pressure reducing unit 43 provided midway along the waste liquid flow path 42. The liquid ejection device 11 includes a waste liquid container 50 that contains the waste liquid discharged from the caps 41 by the discharge mechanism 44.

[0023] 1 and a capping position (shown by a two-dot chain line in FIG. 1) in contact with the nozzle surface 28 of the liquid ejection head 22. When the cap 41 moves to the capping position, the conveyor belt 34 retreats from the support position shown by a solid line in FIG. 2 to the retreat position shown by a two-dot chain line in FIG. 2.

[0024] Capping is performed by the cap 41 moving to the capping position and coming into contact with the nozzle surface 28 of the liquid ejection head 22 so as to surround the nozzle 21. When liquid ejection is not being performed, capping is performed to suppress thickening of the liquid inside the nozzle 21, thereby preventing ejection defects.

[0025] Here, idling is a discharge operation for maintenance in which droplets unrelated to printing are discharged from the nozzles 21 for the purpose of maintaining the liquid discharge head 22. Idling is also called flushing. By performing idling, thickened ink, air bubbles, or foreign matter that may cause discharge defects are discharged from the nozzles 21. The liquid discharged as waste liquid by idling is received in the cap 41. During flushing, maintenance, and at the end of printing, the cap 41 is placed in the capping position. During flushing, idling is performed by the liquid discharge head 22 discharging droplets from the nozzles 21 toward the cap 41.

[0026] Cleaning is performed by driving the decompression unit 43 with the cap 41 placed in the capping position. The cleaning in this example is suction cleaning in which the liquid is sucked and discharged from the nozzle 21 by creating a negative pressure in the substantially closed space between the nozzle surface 28 and the cap 41. A waste liquid flow path 42 is connected to one end of the cap 41 opposite the opening. The other end of the waste liquid flow path 42 is connected to a holder 51 via a decompression unit 43. The cap 41 is in communication with a waste liquid container 50 via the waste liquid flow path 42, the decompression unit 43, and the holder 51.

[0027] The liquid discharged from the nozzle 21 to the cap 41 by cleaning is collected as waste liquid from the cap 41 through the waste liquid flow path 42 in the waste liquid container 50. When a predetermined amount of waste liquid discharged from the nozzle 21 by idle discharge accumulates in the cap 41, the liquid in the cap 41 is collected through the waste liquid flow path 42 into the waste liquid container 50 by driving the pressure reducing unit 43 with the cap 41 separated from the liquid discharge head 22 by a predetermined gap distance. This suction is called idle suction. The idle suction is performed to discharge the liquid accumulated in the cap 41.

[0028] 2, a liquid supply mechanism 60 is provided in the middle of the supply flow path 25 between the liquid container 24 and the liquid ejection unit 20. The liquid supply mechanism 60 has a function of supplying the liquid and pressurizing the liquid to swell the liquid from the nozzle 21 for maintenance purposes.

[0029] <Configuration of liquid supply mechanism 60> Next, the liquid supply mechanism 60 will be described with reference to Fig. 3. The liquid container 24 includes a liquid pack 24A that contains liquid, and a case 24B that contains the liquid pack 24A. When the liquid container 24 is attached to a holder (not shown), the liquid pack 24A is connected to the supply flow path 25, and the case 24B is connected to the first air flow path 71. The liquid container 24 supplies liquid from the liquid pack 24A by pressurizing the space within the case 24B. When the liquid is ink, the liquid pack 24A is an ink pack.

[0030] The liquid supply mechanism 60 includes a sub-tank 61, a self-sealing valve 62, an on-off valve 63, a head tank 64, and the like, which are provided midway through the supply flow path 25. The self-sealing valve 62, the on-off valve 63, and the head tank 64 are provided for each liquid ejection head 22 that constitutes the liquid ejection section 20. The on-off valve 63 is, for example, a choke valve used in choke cleaning, which will be described later.

[0031] In the supply flow path 25, a plurality of flow path valves 65 driven by, for example, a solenoid SL are provided in a portion between the liquid container 24 and the subtank 61. When printing is performed, the flow path valves 65 are opened and the liquid from the liquid container 24 is supplied to the subtank 61. The subtank 61 is provided with an end sensor (not shown) that detects when the amount of liquid contained therein becomes equal to or less than a threshold value. When the end sensor detects the end of the liquid, the flow path valve 65 is closed by the control unit 100. In the example of FIG. 2, each of the supply flow paths 25 connected to the two black liquid containers 24K is connected upstream of the subtank 61. In the middle of each of the supply flow paths 25 connected to the black liquid container 24K, a check valve 29 is provided that allows the supply of liquid in the liquid supply direction from the liquid container 24K to the subtank 61 and prevents the movement of liquid in the opposite direction to the liquid supply direction.

[0032] The liquid supply mechanism 60 includes a pressurizing unit 66 that generates and controls air pressure when the opening / closing valve 63 and the head tank 64 are driven by air pressure. The pressurizing unit 66 pressurizes the liquid in the multiple nozzle groups N1 to N4 (see FIG. 4). The pressurizing unit 66 pressurizes the liquid in the nozzles 21, causing the liquid to bulge out of the nozzles 21.

[0033] The pressurizing unit 66 has a liquid chamber 95 provided in the middle of the supply flow path 25 that supplies liquid to the liquid ejection unit 20, an on-off valve 63 provided upstream of the liquid chamber 95 in the supply flow path 25, and a drive unit 67 capable of displacing a membrane member 97 that constitutes a part of the wall that forms the liquid chamber 95. In other words, the pressurizing unit 66 is composed of the on-off valve 63, the head tank 64, the drive unit 67 that generates and controls the air pressure that drives these, etc. The liquid chamber 95 is configured so that its volume can be changed by the displacement of the membrane member 97. The on-off valve 63 is configured so that the supply flow path 25 can be opened and closed.

[0034] The drive unit 67 includes a motor 67M, a pressurizing pump 67P driven by the motor 67M, a pressure sensor 68 that detects the air pressure pressurized by the pressurizing pump 67P, a selector valve 69 that selects a destination of the pressurized air pressure, and a motor 70 connected to the selector valve 69. The selector valve 69 includes a pressurized tank 69A (not shown) therein. The pressure sensor 68 detects the air pressure in the pressurized tank 69A. The motor 70 is a drive source for the selector valve 69. The control unit 100 controls the rotational position of the motor 70 to select whether each valve (e.g., an on-off valve) in the selector valve 69 should be opened or closed, thereby selecting a destination of the air pressure from the selector valve 69.

[0035] To the selector valve 69 is connected a first air flow path 71, one end of which is connected to the liquid container 24 in order to pressurize the liquid pack 24A (e.g., an ink pack) in the liquid container 24. To the selector valve 69 are also connected the other ends of a second air flow path 72 and a third air flow path 73, each of which has one end connected to an on-off valve 63 for each liquid ejection head 22 and an air chamber of the head tank 64. An atmosphere release valve 71A is provided in the first air flow path 71.

[0036] As shown in FIG. 3, the maintenance section 40 includes a cap unit 75 having a plurality of the above-mentioned caps 41, and a wiping section 76 capable of wiping the nozzle surface. The cap 41 has a bottomed box shape that opens upward, and is configured to be movable relative to the nozzle surface 28 of the liquid ejection head 22. The cap 41 moves from a retracted position in a direction approaching the liquid ejection head 22 to a flushing position where it is separated from the nozzle surface 28 by a gap distance, and to a capping position where it comes into contact with the nozzle surface 28, forming a substantially closed space between the nozzle surface 28 and the cap 41. The position of the cap 41 when the liquid ejection head 22 performs idle ejection is the flushing position.

[0037] The wiping unit 76 has a wiper blade 77 that wipes the nozzle surface 28. With the cap 41 retracted to the retracted position (see FIG. 2 ), the wiping unit 76 moves in the width direction X of the medium M by the driving force of a motor 78, which is the driving source of the wiping unit 76, to wipe the nozzle surfaces 28 of the multiple liquid ejection heads 22.

[0038] The caps 41 are connected to the waste liquid container 50 through the waste liquid flow path 42. A pressure reducing tank (not shown) and a plurality of on-off valves 81 are provided in the waste liquid flow path 42. The plurality of on-off valves 81 are opened and closed by the power of a motor 82 controlled by the control unit 100. When the on-off valve 81 is opened, negative pressure is introduced to the cap 41, and when the on-off valve 81 is closed, negative pressure is not introduced to the cap 41. When the cap 41 is in contact with the nozzle surface 28 of the liquid ejection head 22, negative pressure is introduced into the cap 41, thereby performing suction cleaning in which liquid is forcibly sucked and discharged from the nozzle 21. Note that the cleaning may be pressure cleaning in which the liquid container 24 is pressurized to forcibly discharge the liquid from the nozzle 21.

[0039] The liquid that has been wiped from the nozzle surface 28 accumulates in the wiping unit 76. The portion of the wiping unit 76 where the liquid accumulates is connected to the waste liquid container 50 through a discharge flow path 83. An opening / closing valve 84 is provided in the middle of the discharge flow path 83. When the opening / closing valve 84 is opened under the control of the control unit 100, the waste liquid is collected from the wiping unit 76 through the discharge flow path 83 into the waste liquid container 50.

[0040] <Configuration of the nozzle surface of the liquid ejection unit 20> Next, the configuration of the nozzle surface of the liquid ejection unit 20 will be described with reference to FIG. 4, the liquid ejection section 20 is configured to be capable of recording by ejecting liquid from a plurality of nozzle groups N1 to N4 formed on a nozzle surface 28. In detail, a plurality of unit ejection heads 27 are arranged at regular intervals in the width direction X on the bottom of a liquid ejection head 22 provided in the liquid ejection section 20. The plurality of unit ejection heads 27 are arranged in an attitude inclined at a predetermined angle with respect to the transport direction Y in which the medium M is transported.

[0041] For example, one cap 41, indicated by a two-dot chain line in Fig. 4, faces every three unit discharge heads 27. As shown in Fig. 4, the cap 41 has a parallelogram opening shape in a plan view (i.e., in a bottom view), and is capable of capping every three unit discharge heads 27 that are arranged obliquely with respect to the transport direction Y.

[0042] 5 shows three unit discharge heads 27, which are units capped by one cap 41, among the liquid discharge head 22. Each unit discharge head 27 has a plurality of nozzle groups N1 to N4 (for example, four rows) in which a plurality of nozzles 21 opening on a nozzle surface 28 are arranged in rows. Each of the nozzle groups N1 to N4 has a predetermined number of nozzles 21 arranged in a row along the longitudinal direction of the unit discharge head 27. Although the number of nozzles 21 is simplified in FIG. 5, in reality, one nozzle group is formed by a predetermined number of nozzles 21 within a range of 200 to 1000 (for example, about 400 nozzles).

[0043] The liquid ejection device 11 of this embodiment is capable of color printing. In an example where the liquid is ink, the nozzles 21 include nozzles KN that eject black ink, nozzles YN that eject yellow ink, nozzles MN that eject magenta ink, and nozzles CN that eject cyan ink. The nozzle group N1 is composed of a plurality of nozzles KN arranged in a row at a constant nozzle pitch. The nozzle group N2 is composed of a plurality of nozzles YN arranged in a row at a constant nozzle pitch. The nozzle group N3 is composed of a plurality of nozzles MN arranged in a row at a constant nozzle pitch. The nozzle group N4 is composed of a plurality of nozzles CN arranged in a row at a constant nozzle pitch.

[0044] The nozzles KN, YN, MN, and CN are arranged at equal intervals for each color across the entire width of the medium M at its widest when projected in the transport direction Y. In other words, this equal distance becomes the dot pitch when printed on the medium M. In this way, in the liquid ejection head 22, the unit ejection heads 27 are arranged at a predetermined inclination angle so that the projected nozzles when the nozzles 21 are projected in the transport direction Y are arranged in the width direction at a pitch according to the printing resolution.

[0045] 5, in the liquid ejection unit 20, the nozzle group N1, which is a group of black nozzles KN, and the nozzle group N2, which is a group of yellow nozzles YN, are adjacent to each other, and the nozzle group N3, which is a group of magenta nozzles MN, and the nozzle group N4, which is a group of cyan nozzles CN, are adjacent to each other. For this reason, yellow and black tend to mix, and cyan and magenta tend to mix. When mixed inks are ejected from the mixed nozzles 21, streaks of the mixed colors tend to occur in the print on the medium M. In particular, when black ink is mixed with the yellow nozzles YN, dark streaks occur on the light-color print, so the streaks due to the mixed colors are easily noticeable.

[0046] 5, the nozzle surface 28 of the liquid ejection section 20 is wiped by the wiping section 76 moving in the width direction X. This wiping wipes the openings of the nozzles 21 constituting the multiple nozzle groups N1 to N4 together with the nozzle surface 28. The bottom surface of the liquid ejection head 22 is formed so that the unit ejection heads 27 and the remaining portions are substantially flush with each other, and the entire bottom surface serves as the nozzle surface 28 that is wiped by the wiping section 76.

[0047] In this embodiment, when the wiping unit 76 wipes the nozzle surface 28, the liquid in the nozzles 21 is pressurized by the pressurizing unit 66 (see FIG. 3). The wiping unit 76 wipes the nozzle surface 28 in a state in which the liquid swells out from all of the nozzles 21 due to the pressurization. The details of the control during wiping will be described later.

[0048] <Configuration and operation of the pressure unit 66> Next, the configuration and operation of the pressurizing unit 66 will be described with reference to Figs. 6 to 9. The aforementioned self-sealing valve 62, the on-off valve 63, and the head tank 64, which constitute the pressurizing unit 66, are provided in the middle of the supply flow path 25 in this order along the liquid supply direction. The self-sealing valve 62 opens the supply flow path 25 due to the difference between the pressure of the supply flow path 25 and the atmospheric pressure. That is, the self-sealing valve 62 opens the supply flow path 25 and replenishes ink from the upstream side when liquid is consumed from the liquid ejection head 22 and the downstream side becomes negative pressure. The self-sealing valve 62 has a valve body (not shown) that opens and closes the supply flow path 25, a biasing member (not shown) that biases the valve body in a direction to close it, and a flexible member (not shown) that receives atmospheric pressure and pushes the valve body open against the bias of the biasing member when the supply flow path 25 becomes negative pressure.

[0049] The on-off valve 63 is provided downstream of the self-sealing valve 62. The on-off valve 63 includes a liquid chamber 91 that forms a part of the supply flow path 25, and an air chamber 92 that is separated from the liquid chamber 91 via a membrane member 93. The on-off valve 63 opens and closes the supply flow path 25 by deforming the membrane member 93 due to the pressure difference between the liquid chamber 91 and the air chamber 92. The operating pressure of the on-off valve 63 can be adjusted by an operating pressure adjustment spring 94.

[0050] The liquid chamber 91 is formed inside the housing of the on-off valve 63, and a part of the wall thereof is formed by the membrane member 93. The inlet of the liquid chamber 91 is formed in the bottom surface 91a, and the outlet of the liquid chamber 91 is formed above the bottom surface 91a. Therefore, when the membrane member 93 is recessed toward the bottom surface 91a, the outlet of the liquid chamber 91 is blocked. This allows the on-off valve 63 to block the supply flow path 25.

[0051] The air chamber 92 is located in the internal space of the housing of the on-off valve 63, separated from the liquid chamber 91 by a membrane member 93. The membrane member 93 is formed, for example, from a flexible resin film (e.g., elastomer, etc.). The membrane member 93 is fixed to the inner wall surface of the on-off valve 63 with a predetermined slack so as to cover the inlet and outlet of the liquid chamber 91. The operating pressure adjusting spring 94 adjusts the operating pressure of the on-off valve 63, is disposed in the liquid chamber 91, and biases the membrane member 93 toward the air chamber 92.

[0052] The head tank 64 is provided downstream of the on-off valve 63. The head tank 64 includes a liquid chamber 95 that forms a part of the supply flow path 25, and an air chamber 96 that is separated from the liquid chamber 95 via a membrane member 97, and the membrane member 97 is deformed by the pressure difference between the liquid chamber 95 and the air chamber 96, thereby changing the spatial volume of the liquid chamber 95. The operating pressure of the head tank 64 can be adjusted by an operating pressure adjustment spring 98.

[0053] The liquid chamber 95 is formed inside the head tank 64, and a part of the wall surface thereof is formed by a membrane member 97. The inlet and outlet of the liquid chamber 95 are formed below the bottom surface 95a. Therefore, even if the membrane member 97 is recessed toward the bottom surface 95a, the supply flow path 25 in the head tank 64 is not blocked. The air chamber 96 is located in the internal space of the head tank 64, on the opposite side to the liquid chamber 95 across the membrane member 97.

[0054] The membrane member 97 is formed of, for example, a flexible resin film (e.g., elastomer, etc.). The membrane member 97 is fixed to the inner wall surface of the head tank 64 with a predetermined slack so as to cover the inlet and outlet of the liquid chamber 95. The working pressure adjustment spring 98 adjusts the working pressure of the head tank 64, is disposed in the liquid chamber 95, and biases the membrane member 97 toward the air chamber 96.

[0055] The supply flow passage 25 , which communicates with the outlet of the liquid chamber 95 of the head tank 64 , is connected to the liquid ejection head 22 . For example, when cleaning is performed, a capping state is established in which the cap 41 comes into contact with the nozzle surface 28. When the wiping unit 76 wipes the nozzle surface 28, a small amount of liquid is discharged from the nozzles 21 in advance, compared to that during cleaning. After this discharge, the wiping unit 76 wipes the nozzle surface 28 in a state in which the liquid bulges out of the nozzles 21. Note that the liquid may only bulge out of the nozzles 21, without being discharged from the nozzles 21.

[0056] The cleaning includes a first cleaning (wiping cleaning) performed before wiping, and a second cleaning performed by the maintenance unit 40. The first cleaning includes wiping cleaning, which replaces a small amount of ink to restore the ejection characteristics of the liquid ejection head 22. The second cleaning includes normal cleaning, which replaces ink with the opening / closing valve 63 open, and choke cleaning, which opens and closes the opening / closing valve 63 to replace ink.

[0057] <About the first cleaning> Next, the first cleaning will be described with reference to Fig. 6 to Fig. 15. In wiping cleaning, the selector valve 69 is switched, and air is introduced into the air chamber 92 of the on-off valve 63, as shown in Fig. 6. This causes the membrane member 93 to bend from the open position shown by the two-dot chain line in Fig. 6 to the closed position shown by the solid line, and the on-off valve 63 is closed.

[0058] Next, the selector valve 69 is switched, and air is introduced into the air chamber 96 of the head tank 64 with the on-off valve 63 closed, as shown in Fig. 7. This causes the membrane member 97 to bend from the non-pressurized position shown by the two-dot chain line in Fig. 7 to the pressurized position shown by the solid line, thereby pressurizing the liquid in the liquid chamber 95. In this manner, the first cleaning is performed.

[0059] This first cleaning will be described with reference to Figs. 10 to 12, which show a cross section of the nozzle. As shown in Fig. 10, the liquid IL in the nozzle 21 of the liquid ejection head 22 forms a meniscus MS having a concave shape that is recessed from the opening of the nozzle 21 deeper than the nozzle surface 28. From this state, the liquid pushed out (pressurized) from the liquid chamber 95 by the film member 97 in the head tank 64 being moved to the pressurizing position shown in Fig. 7 is discharged from the nozzle 21 in a small amount according to the volume of the liquid chamber 95. As a result, as shown in Fig. 11, the liquid IL bulges out from the nozzle 21. In the process of forming this bulging portion EL, the liquid IL may be discharged from the nozzle 21, or the pressurized liquid may remain in a state of bulging out from the opening of the nozzle 21 without being discharged.

[0060] As shown in Fig. 11, the wiping unit 76 wipes the nozzle surface 28 while the liquid is swelling out of the nozzle 21. For example, if wiping is performed while a concave meniscus MS is formed as shown in Fig. 10, a film of the wiped liquid IL is formed outside the concave of the meniscus MS, and air is trapped between the film and the meniscus MS. This air may become air bubbles and adversely affect the liquid ejection performance during subsequent printing.

[0061] 11, when the bulging portion EL where the liquid IL bulges out from the nozzle 21 is wiped by the wiping portion 76, it is possible to avoid trapping air in the liquid IL in the nozzle 21, and therefore it is possible to prevent air bubbles from being mixed into the nozzle 21. In addition, by discharging a small amount of liquid IL, the thickened liquid IL or air bubbles in the nozzle 21 are discharged from the nozzle 21.

[0062] As shown in FIG. 8, when the air chamber 92 of the on-off valve 63 is depressurized to atmospheric pressure, the membrane member 93 is bent in the expanding direction, and the on-off valve 63 is opened. Next, as shown in Fig. 9, the air chamber 96 of the head tank 64 is depressurized to atmospheric pressure, displacing the membrane member 97 of the head tank 64 from the pressurized position to the non-pressurized position. As a result, a force acts on the liquid chamber 95 to suck in the liquid from the nozzle 21 side. Therefore, as shown in Fig. 13, the liquid IL in the nozzle 21 is sucked in toward the back. As a result, a meniscus MS of the liquid IL is formed at the opening of the nozzle 21.

[0063] For example, as shown in Fig. 14, when the wiping unit 76 wipes the nozzle surface 28, the liquid IL that accumulates along the ridge of the wiper blade 77 may remain on the nozzle surface 28 for some reason. The adhering liquid WL that remains on the nozzle surface 28 is a mixed-color liquid. As shown in Fig. 14, this remaining adhering liquid WL may come into contact with the nozzles 21. In this case, the mixed-color adhering liquid WL may be sucked into the nozzles 21 by suction when the head tank 64 subsequently moves from the pressurized position to the non-pressurized position, as shown in Fig. 15.

[0064] In this embodiment, the mixed-color adhering liquid WL in contact with the nozzle 21 shown in FIG. 14 is detected. After the detection, the nozzle 21 (see FIG. 15) that may have aspirated the mixed-color liquid IL is identified. From the identified nozzle 21, a blank discharge is performed with a blank discharge amount larger than a normal blank discharge amount. For example, if blank discharge is performed with an amount that can uniformly discharge the aspirated mixed-color adhering liquid WL for the nozzle 21 that has aspirated the mixed-color adhering liquid WL and the nozzle 21 that has not aspirated it, excess liquid is discharged wastefully for the nozzle 21 that has not aspirated the mixed-color adhering liquid WL. Therefore, in this embodiment, the nozzle 21 that has aspirated the mixed-color adhering liquid WL is detected, and for the specific nozzle 21 identified based on the detection result, a first blank discharge indicated by a large white arrow in FIG. 15 is performed in which the liquid IL is discharged from the nozzle 21 with a first discharge amount that can discharge the mixed-color adhering liquid WL. Then, for the normal nozzles 21 other than the specific nozzle 21, a second dummy discharge is performed, which discharges the liquid IL at a second discharge amount that is smaller than the first discharge amount, as indicated by the small white arrow in FIG.

[0065] <Configuration of the drive system of the liquid ejection head 22> Next, with reference to FIG. 16, a detailed configuration of a portion including a drive system for ejecting liquid from the liquid ejection head 22 will be described.

[0066] The liquid ejection head 22 includes an ejection section D provided for each nozzle 21. The ejection section D shown in Fig. 16 includes a nozzle 21, an actuator 200, a cavity 264 (pressure chamber), and a vibration plate 265. The nozzle 21 is in communication with the cavity 264. The actuator 200 is driven to vibrate the vibration plate 265, causing the ejection section D to eject liquid (e.g., ink) from the cavity 264 through the nozzle 21. Fig. 16 shows one of the ejection sections D, the number of which is the same as the number of nozzles 21.

[0067] The liquid ejection section 20 includes ejection sections D shown in FIG. 16 in the same number as the nozzles 21. That is, the liquid ejection section 20 includes a plurality of actuators 200 provided corresponding to the plurality of nozzles 21 constituting the plurality of nozzle groups N1 to N4, and a plurality of diaphragms 265. The plurality of actuators 200 are individually driven by a head driving circuit 110 (see FIG. 18) as an example of a driving circuit, thereby partially displacing the plurality of diaphragms 265. The displaced diaphragm 265 ejects liquid from the nozzle 21 corresponding to the driven actuator 200.

[0068] The cavity 264 is a space defined by a cavity plate 266 molded into a predetermined shape having a recess, a nozzle plate 267 in which the nozzles 21 are formed, and a vibration plate 265. The cavity 264 communicates with a reservoir 272 through a liquid supply port 271. The reservoir 272 communicates with one liquid container 24 through a liquid supply flow path 273.

[0069] The actuator 200 may be, for example, a unimorph (monomorph) type piezoelectric element as shown in FIG. 16. In this case, the piezoelectric element constituting the actuator 200 has a lower electrode 201, an upper electrode 202, and a piezoelectric body 203 provided between the lower electrode 201 and the upper electrode 202. The lower electrode 201 is set to a predetermined reference potential VSS, and a drive signal Vin is supplied to the upper electrode 202, so that a voltage is applied between the lower electrode 201 and the upper electrode 202 in the actuator 200. In response to the applied voltage, the actuator 200 bends and vibrates in the vertical direction in FIG. 3. In this example, the lower electrode 201 is a common electrode common to the multiple actuators 200, and the upper electrode 202 is an individual electrode that supplies the drive signal Vin to the multiple actuators 200 individually.

[0070] The lower electrode 201 of the actuator 200 is joined to the vibration plate 265, which is disposed so as to close the upper opening of the cavity plate 266. Therefore, when the actuator 200 vibrates due to the drive signal Vin, the vibration plate 265 also vibrates. Then, the volume of the cavity 264 changes due to the vibration of the vibration plate 265, and accordingly, the pressure of the liquid in the cavity 264 changes, so that part of the liquid filled in the cavity 264 is ejected from the nozzle 21.

[0071] The amount of liquid in the cavity 264 reduced by the ejection of the liquid is replenished by the supply of liquid from the reservoir 272 to the cavity 264. In addition, the liquid is supplied to the reservoir 272 from the liquid container 24 through a liquid supply flow path 273. The liquid supply flow path 273 communicates with the supply flow path 25 shown in FIG.

[0072] In this embodiment, a piezoelectric element is used as the actuator 200, but the actuator 200 is not limited to a piezoelectric element. For example, the actuator 200 may be configured to include an electrostatic element, or may be a heater element that heats and boils a liquid such as ink, and ejects the liquid from the nozzle 21 by the force of bubbles.

[0073] <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. 17. As shown in FIG. 17, the control unit 100 is electrically connected to the operation unit 15, the liquid ejection unit 20, the transport unit 30, the maintenance unit 40, the pressurizing unit 66, the wiping unit 76, and the like. The control unit 100 includes a computer 101 and an electronic circuit such as an FPGA (field-programmable gate array). The control unit 100 includes a print control unit 102 and a nozzle inspection unit 103. The print control unit 102 and the nozzle inspection unit 103 are composed of at least one of the computer 101 and the electronic circuit. The computer 101 includes a storage unit 105. The storage unit 105 stores a program such as a maintenance control routine shown in the flowchart of FIG. 28. The control unit 100 executes the program such as a maintenance control routine by the computer 101.

[0074] The control unit 100 is not limited to a device that performs software processing for all of the processes it executes. For example, the control unit 100 may be equipped with a dedicated hardware circuit (e.g., an application specific integrated circuit: ASIC) that performs hardware processing for at least a part of the processes it executes. That is, the control unit 100 may be configured as a circuit including one or more processors that operate according to a computer program (software), one or more dedicated hardware circuits that execute at least a part of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions that are configured to cause the CPU to execute the processes. Memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. The control unit 100 may be configured at least in part by hardware. That is, the control unit 100 may be realized by cooperation between software and hardware, or by hardware.

[0075] The print control unit 102 is responsible for various types of control such as print control, maintenance control, wiping control, etc. The print control unit 102 controls a plurality of ejection units D by, for example, outputting a control signal to a head drive circuit 110 as an example of a drive circuit in the liquid ejection head 22 shown in FIG.

[0076] The nozzle inspection unit 103 performs a nozzle inspection to check whether or not there is an ejection abnormality in the nozzles 21 of the liquid ejection head 22. The nozzle inspection unit 103 detects nozzles with ejection abnormalities by the nozzle inspection. The nozzle inspection unit 103 of this example inspects the nozzles 21 for ejection abnormalities based on a detection signal from an ejection abnormality detection unit 112 (see FIG. 17) described later.

[0077] <Electrical configuration related to discharge control and discharge abnormality detection> Next, an electrical configuration related to the control of the liquid ejection head 22 and the detection of ejection abnormalities performed by the control unit 100 will be described with reference to Fig. 18. As shown in Fig. 18, the control unit 100 is electrically connected to the liquid ejection head 22 via a wiring cable (not shown) in a state in which various signals Sw, SI, COM, and Ds can be transmitted and received.

[0078] The liquid ejection head 22 includes a head drive circuit 110 and an ejection unit 130. The head drive circuit 110 includes a drive signal generation unit 111 that generates a drive signal Vin based on signals SI and COM input from the print control unit 102, and an ejection abnormality detection unit 112 that detects an ejection abnormality (abnormal nozzle) of the nozzle 21 based on a residual vibration signal Vout from the ejection unit D. In this embodiment, the ejection abnormality detection unit 112 and the nozzle inspection unit 103 form a detection unit 106. The detection unit 106 detects the nozzle 21 in contact with the adhering liquid WL adhering to the nozzle surface 28 based on the residual vibration of the displaced vibration plate 265.

[0079] The head driving circuit 110 also includes a switching unit 113 that switches the connection destination of the discharge unit D between the drive signal generation unit 111 and the discharge abnormality detection unit 112. The switching unit 113 switches between a first connection state in which the discharge unit D and the drive signal generation unit 111 are electrically connected, and a second connection state in which the discharge unit D and the discharge abnormality detection unit 112 are electrically connected, based on a switching signal Sw from the nozzle inspection unit 103. In other words, the switching unit 113 switches between outputting the drive signal Vin from the drive signal generation unit 111 to the discharge unit D and inputting the residual vibration signal Vout from the discharge unit D to the discharge abnormality detection unit 112.

[0080] When a drive signal Vin is supplied from the head drive circuit 110 to an actuator 200 (see FIG. 16) provided in the ejection section D, the vibration plate 265 of the ejection section D is deflected upward by the electrostrictive action of the piezoelectric element constituting the actuator 200, and then restored by its elastic restoring force. At this time, a droplet is ejected from the nozzle 21 communicating with the cavity 264 (see FIG. 16) by the pressure applied to the liquid (e.g., ink) in the cavity 264.

[0081] The drive signal generating unit 111 generates a drive signal Vin for driving each of the multiple discharge units D of the discharge unit 130 based on control signals such as the path data SI and the drive waveform signal COM supplied from the print control unit 102. Each discharge unit D is driven based on the supplied drive signal Vin, and discharges the liquid filled inside from the nozzle 21 to the medium M. The drive signal generating unit 111 can generate a drive signal Vin including a voltage waveform capable of vibrating the diaphragm 265 with an amplitude capable of discharging the liquid from the nozzle 21, and a drive signal Vin including a voltage waveform that slightly vibrates the diaphragm 265 with a small amplitude so as not to discharge the liquid from the nozzle 21. The nozzle inspection by the detection unit 106 is performed by slightly vibrating the diaphragm 265, but may also be performed by discharging droplets from the nozzle 21.

[0082] The ejection abnormality detection unit 112 inputs a residual vibration signal Vout output by the actuator 200 that receives the residual vibration of the liquid in the cavity 264 of the ejection unit D via a vibration plate 265 (see FIG. 16) after the ejection unit D is driven by a drive signal Vin. The ejection abnormality detection unit 112 detects whether the nozzle 21 to be inspected is a normal nozzle capable of normally ejecting droplets, or an abnormal nozzle that cannot normally eject droplets, based on the input residual vibration signal Vout, and outputs the detection result as a detection signal Ds to the control unit 100. If the detection result is an abnormal nozzle, the ejection abnormality detection unit 112 outputs a detection signal Ds for a number of causes (air bubble contamination, drying, adhesion of paper powder) together with nozzle position information that can identify the position of the abnormal nozzle.

[0083] In the ejection abnormality inspection, after the ejection operation of one ink droplet or one vibration operation for micro-vibrating the ink in the nozzle 21 is completed, vibration due to the excitation remains in the diaphragm 265 of each ejection unit D until the start of the next vibration operation. The residual vibration generated in the diaphragm 265 of the ejection unit D can be assumed to have a natural vibration frequency determined by the acoustic resistance Res due to the shape of the nozzle 21 or the liquid supply port 271 or the viscosity of the ink, the inertance Int due to the weight of the ink in the flow path, and the compliance Cm of the diaphragm 265, etc.

[0084] Fig. 19 shows an equivalent circuit representing a calculation model of simple harmonic motion assuming residual vibration of diaphragm 265 based on the above assumption. This calculation model of the residual vibration of diaphragm 265 is expressed by sound pressure Ps, inertance Int, compliance Cm, and acoustic resistance Res. Then, the step response when sound pressure Ps is applied to the circuit of Fig. 19 can be calculated for volume velocity Uv. can be.

[0085] FIG. 20 is a graph showing the waveform of the residual vibration signal Vout. As shown in FIG. 20, when the discharge unit D normally discharges droplets, the residual vibration signal Vout has a predetermined waveform in normal times (see "normal time L0" in FIG. 20). However, in the case of abnormal discharge where the discharge of droplets is abnormal, the waveform of the residual vibration signal Vout differs from that in normal times. In detail, as shown in FIG. 20, when air bubbles are mixed in the liquid in the nozzle 21 or the cavity 264, the residual vibration signal Vout has a residual vibration waveform L1 when air bubbles are mixed in. In addition, when the liquid in the nozzle 21 is thickened or solidified due to drying, the residual vibration signal Vout has a residual vibration waveform L2 when dry. Furthermore, when paper powder is attached to the opening of the nozzle 21, the residual vibration signal Vout has a residual vibration waveform L3 when paper powder is attached, which has a larger period than that in normal discharge. From the above, it is possible to detect abnormal discharge of droplets from the liquid discharge head 22 according to the cause by the difference in residual vibration.

[0086] 14, when the mixed color liquid WL adheres to the nozzle face 28 while in contact with the nozzle 21, the weight of the liquid increases and the inertance Int increases. For this reason, the waveform of the residual vibration signal Vout differs between the nozzle 21 that is in contact with the mixed color liquid WL adhering to the nozzle face 28 and the nozzle 21 that is not in contact with the mixed color liquid WL. Note that the mixed color liquid WL in contact with the nozzle 21 also includes the mixed color liquid WL and the opening of the nozzle 21 in contact.

[0087] <Method of detecting the liquid adhesion state on the nozzle surface 28> Next, referring to FIG. 21, a detection example will be described in which the nozzle inspection unit 103, which inspects the nozzles 21 for ejection defects, is used to detect the liquid adhesion state on the nozzle surface 28. The graph shown in FIG. 21 shows a detection example in which the nozzles 21 in contact with the liquid adhering to the nozzle surface 28 are detected. The horizontal axis of this graph indicates the positions of n nozzles 21 arranged in the width direction X. In this graph, n is an example of about 240 nozzles. The vertical axis indicates the amplitude (V) of the residual vibration signal Vout. The amplitude is indicated by voltage. In the graph of FIG. 21, the lower limit V1 and the upper limit V2 indicated by the dashed line indicate the lower limit and upper limit of the normal range in which the amplitude of a normal nozzle 21 that is not in contact with the liquid adhering to the nozzle surface 28, i.e., the adhering liquid WL (see FIG. 14 and FIG. 15), falls. The amplitude of an abnormal nozzle that is in contact with the adhering liquid WL deviates from this normal range. As shown in FIG. 21, the amplitude of the nozzle 21 in contact with the adhering liquid WL deviates from the normal range to the larger side. Therefore, by utilizing the mechanism of nozzle inspection, it is possible to detect whether the nozzle 21 is an abnormal nozzle in contact with the adhering liquid WL, or a normal nozzle 21 not in contact with the adhering liquid WL, based on the amplitude of the residual vibration signal Vout.

[0088] In the graph of FIG. 21, dark dots indicate a detection example when no liquid is attached to the nozzle surface 28, and white dots indicate a detection example when liquid is attached to the nozzle surface 28. In the example shown in FIG. 21, the abnormal nozzles 21 in contact with the attached liquid WL form a group, and these groups of abnormal nozzles are called contact nozzle groups NG1. In the example of FIG. 21, the contact nozzle groups NG1 appear in two places. In this embodiment, these contact nozzle groups NG1 are also called "first nozzle groups NG1." Then, normal nozzles 21 other than the first nozzle group NG1 have amplitude values ​​within the normal range. Incidentally, one nozzle nf indicated by a white dot having an amplitude within the normal range within the range in which the contact nozzle group NG1 shown in FIG. 21 exists is presumed to be a false detection. For this reason, in consideration of this type of false detection, it may be appropriate to consider the nozzles adjacent to the abnormal nozzles belonging to the first nozzle group NG1 as abnormal nozzles.

[0089] Then, the nozzle 21 in contact with the adhering liquid WL will suck the mixed color adhering liquid WL into the nozzle 21 when the pressure is released (see FIG. 14 and FIG. 15). Therefore, in order to discharge the mixed color liquid WL that the nozzle 21 has sucked in from the nozzle 21, a blank discharge is performed in which liquid unrelated to printing is discharged from the nozzle 21. The amount of the mixed color liquid WL that the nozzle 21 has sucked in is an amount according to the capacity of the liquid chamber 95, since the head tank 64 has moved from the pressurized position to the non-pressurized position. Therefore, in order to discharge the mixed color liquid WL that the nozzle 21 has sucked in by blank discharge, the liquid is discharged in a blank discharge amount that is larger than that of normal blank discharge. In this embodiment, the blank discharge for discharging the mixed color liquid in a blank discharge amount that is larger than that of normal blank discharge is also referred to as a first blank discharge. In contrast to this, the blank discharge from the nozzle 21 other than the mixed color liquid compatible nozzle is also referred to as a second blank discharge.

[0090] <How to identify the first nozzle> Next, with reference to Figs. 22 to 27, three examples of a method for determining the nozzle 21 to be subjected to the first blank discharge after wiping the nozzle surface 28 will be described. Here, in Figs. 22 to 27, the nozzle 21 whose amplitude deviates from the normal range in the nozzle inspection by the detection unit 106 due to contact with the adhering liquid WL is referred to as an "abnormal nozzle 21N", and the other nozzles whose amplitude is within the normal range are referred to as "normal nozzles 21G". In addition, the nozzle 21 to be subjected to the first blank discharge for discharging the mixed color liquid is referred to as the first nozzle FN1, and the normal nozzle 21G other than the first nozzle FN1 is referred to as the second nozzle FN2. Note that the first nozzle FN1, which is the nozzle 21 to be subjected to the first blank discharge to prevent color mixing, is also a color mixing prevention compatible nozzle.

[0091] (First embodiment) A first embodiment shown in Figures 22 and 23 will be described. In the first embodiment, only the first nozzle group NG1 in contact with the adhering liquid WL is targeted for the first dummy discharge. The first discharge amount, which is the dummy discharge amount from the nozzle 21 detected by the detection unit 106, is set to be greater than the second discharge amount, which is the dummy discharge amount from the other nozzles. Note that the "dummy discharge amount from the other nozzles" may include a discharge amount of 0. In other words, the second dummy discharge amount may be 0.

[0092] (Second Example) A second embodiment will be described with reference to Figures 24 and 25. In the second embodiment, the first nozzles FN1 that are the targets of the first dummy discharge are not only the abnormal nozzle 21N constituting the first nozzle group NG1 that is in contact with the adhering liquid WL, but also the normal nozzles 21G that are adjacent to the abnormal nozzle 21N by a number of nozzles.

[0093] In this case, the greater the number A of abnormal nozzles 21N in contact with one adhering liquid WL, the greater the number of normal nozzles 21G to be the target of the first blank discharge of the predetermined number a adjacent to the abnormal nozzle 21N. In the case where the number of abnormal nozzles 21N in contact with the adhering liquid WL shown in FIG. 24 is two, the predetermined number a, which is the number of normal nozzles 21G to be the target of the first blank discharge adjacent to the abnormal nozzle 21N, is one, and the total number of first nozzles FN1 is four. In contrast, in the example of the cross-sectional view of the liquid discharge head 22 shown in FIG. 25, the number of abnormal nozzles 21N in contact with a large adhering liquid WL is six. In the case where the number of abnormal nozzles 21N in contact with the adhering liquid WL is six, the predetermined number a, which is the number of normal nozzles 21G to be the target of the first blank discharge adjacent to the abnormal nozzle 21N, is three, and the total number of first nozzles FN1 is twelve.

[0094] In other words, the greater the number A of abnormal nozzles 21N in contact with the adhering liquid WL, the greater the predetermined number a, which is the number of normal nozzles 21G that are adjacent to the abnormal nozzle 21N and should be the target of the first dummy discharge. In other words, when the number of abnormal nozzles 21N in contact with the adhering liquid WL is B (B>A), which is greater than A, the predetermined number a2 of normal nozzles 21G that are adjacent to the abnormal nozzle 21N and should be the target of the first dummy discharge is set to a value greater than the predetermined number a1 when the number is A (a2>a1).

[0095] (Third Example) Next, a third embodiment shown in FIG. 26 and FIG. 27 will be described. In the third embodiment, when a plurality of liquids WL contact the nozzle surface 28, the normal nozzle 21G located between the plurality of adhering liquids WL is identified as the first nozzle FN1 by a method different from that of the second embodiment. In the third embodiment, when the number of normal nozzles 21G located between the plurality of adhering liquids WL is equal to or less than the specified number K, the normal nozzles 21G located consecutively from the abnormal nozzle 21N to the adjacent normal nozzles F1 are identified as the first nozzle FN1. F1 is set to be f1 more than the specified number a in the second embodiment (F1=a+f1). FIG. 26 shows an example where f1 is 1. In this case, even if there is a false detection nozzle nf shown in FIG. 21, the nozzle nf can be identified as the first nozzle FN1 that is the target of the first blank discharge. In this respect, the specified number K may be, for example, 1 or 2. The specified number K is not limited to 1 or 2, and may be set to an appropriate value within the range of K=3 to 10, or may be set to a value exceeding 10, for example.

[0096] Fig. 27 shows an example in which the number of normal nozzles 21G located between two adhering liquids WL exceeds the specified number K. In this case, as shown in Fig. 27, for normal nozzles 21G located between a plurality of contact nozzle groups NG1 in contact with a plurality of adhering liquids WL, the method of the second embodiment is applied to identify them as first nozzles FN1. That is, according to the number of abnormal nozzles 21N belonging to the plurality of contact nozzle groups NG1 in contact with a plurality of adhering liquids WL, a predetermined number a of normal nozzles 21G adjacent to the abnormal nozzle 21N are identified as first nozzles FN1.

[0097] <Operation of the embodiment> Next, the operation of the liquid ejection device 11 in this embodiment will be described. The following will be described with reference to the flowchart shown in Fig. 28. The control unit 100 executes a cleaning control routine shown in Fig. 28 while the power supply of the liquid ejection device 11 is on. By executing this routine, first cleaning and wiping are performed when the wiping conditions are met.

[0098] First, in step S11, the control unit 100 determines whether or not it is time for wiping. If it is time for wiping, the process proceeds to step S12, and if it is not time for wiping, the process waits.

[0099] In step S12, the control unit 100 pressurizes the nozzle. More specifically, the control unit 100 controls the motor 70 to selectively control the selector valve 69, thereby closing the on-off valve 63 and pressurizing the head tank 64 with the on-off valve 63 in the closed state. As a result, the membrane member 97 is deformed from the non-pressurized position to the pressurized position by the air introduced into the air chamber 96 of the head tank 64. As a result, the liquid in the liquid chamber 95 is pushed downstream in the liquid supply direction. An amount of liquid IL corresponding to the volume of the liquid chamber 95 of the head tank 64 is pushed out from the nozzle 21. This pressurization of the liquid causes the liquid IL to swell from the nozzle 21 as shown in FIG. 11. That is, a bulging portion EL is generated in which the liquid IL swells from the nozzle 21 in the discharge direction beyond the nozzle surface 28. At this time, the bulging portion EL may be generated as a result of a small amount of liquid IL being discharged from the nozzle 21, or the liquid IL may swell from the nozzle 21 without being discharged from the nozzle 21.

[0100] In step S13, the control unit 100 performs wiping. More specifically, the control unit 100 controls the motor 78 to move the wiping unit 76 in the width direction X along the wiping path. This causes the wiping unit 76 to wipe the nozzle surface 28 with the wiper blade 77. As a result, as shown in FIGS. 12 and 14, the nozzle surface 28 is wiped by the wiping unit 76, and the bulging portion EL bulging from the nozzle 21 is removed. As shown in FIGS. 12 and 14, the portion of the liquid in the nozzle 21 exposed to the opening is flattened to be approximately flush with the nozzle surface 28.

[0101] 14, after being wiped away by the wiping unit 76, some of the mixed color liquid wiped away by the wiping unit 76 may remain on the nozzle surface 28. For example, some of the wiped liquid may remain attached to the nozzle surface 28 due to wear (e.g., uneven wear) of the wiper blade 77 of the wiping unit 76, scratches, uneven contact, vibration, etc.

[0102] In step S14, the control unit 100 performs a nozzle inspection. This nozzle inspection is performed with the head tank 64 in the pressurized position. That is, before returning the membrane member 97 of the head tank 64 from the pressurized position to the non-pressurized position after pressurization, the nozzle inspection is performed with the membrane member 97 in the pressurized position. This is because, as shown in FIG. 14, after the mixed-color adhering liquid WL is sucked into the nozzle 21, it is not possible to detect the presence of the mixed-color adhering liquid WL on the nozzle surface 28, so the nozzle inspection is performed with the mixed-color adhering liquid WL on the nozzle surface 28. In this embodiment, the nozzle inspection is used to detect the adhering liquid WL adhering to the nozzle surface 28.

[0103] The nozzle inspection is performed as follows. A drive signal is applied to the actuator 200 to vibrate the vibration plate 265. Next, the control unit 100 switches the switching unit 113. The ejection abnormality detection unit 112 inputs the residual vibration signal Vout. Based on the residual vibration signal Vout, the nozzle 21 (abnormal nozzle 21N) that is in contact with the mixed-color liquid WL is detected. At this time, since the thickened liquid, air bubbles, paper powder, etc. in the nozzle 21 have already been removed from the nozzle 21 by the first cleaning, the nozzle 21 that is in contact with the mixed-color liquid can be detected with less erroneous detection compared to when the first cleaning is performed. Note that the processing of steps S13 and S14 corresponds to "wiping the nozzle surface 28 by the wiping unit 76 and performing detection by the detection unit 106 while maintaining the operation of the pressurizing unit 66 during pressurization."

[0104] In step S15, the control unit 100 releases the pressure on the nozzle 21. As a result, as shown in Fig. 13 and Fig. 15, the adhering liquid WL is sucked toward the back of the nozzle 21. At this time, as shown in Fig. 15, the adhering liquid WL of the mixed colors in contact with the nozzle 21 is sucked toward the back of the nozzle 21 by a predetermined amount according to the volume of the liquid chamber 95.

[0105] The release of the pressurization may be performed at any time after the nozzle inspection and before the blank ejection is performed. The process of step S15 corresponds to "release of the pressurization operation of the pressurizing unit 66."

[0106] In step S16, the control unit 100 judges whether or not there is a contact nozzle group. The control unit 100 judges whether or not there is a contact nozzle group based on the detection result of the detection unit 106. If there is a contact nozzle group, the process proceeds to step S17, and if there is no contact nozzle group, the process proceeds to step S19. For example, as shown in FIG. 21, the control unit 100 judges a nozzle 21 whose amplitude of the residual vibration signal Vout is within a normal range as a normal nozzle 21G, and judges a nozzle 21 whose amplitude of the residual vibration signal Vout is out of the normal range as an abnormal nozzle 21N. The group of abnormal nozzles 21N is the contact nozzle group NG1 that contacts the adhering liquid WL. Note that in this embodiment, the contact nozzle group NG1 includes a case where there is one abnormal nozzle 21N.

[0107] In step S17, the control unit 100 identifies the color mixing prevention compatible nozzle corresponding to the contact nozzle group. Based on the abnormal nozzle 21N constituting the contact nozzle group NG1 detected by the detection unit 106 by any of the methods of the first to third embodiments, the color mixing prevention compatible nozzle is identified. The color mixing prevention compatible nozzle refers to the first nozzle FN1 which is a nozzle targeted for the first dummy discharge that discharges liquid at the first dummy discharge amount. By identifying the color mixing prevention compatible nozzle, the color mixing prevention compatible nozzle to which the first dummy discharge amount is set and the other normal nozzles 21G to which the second dummy discharge amount is set are set for all the nozzles 21. In other words, the first dummy discharge amount or the second dummy discharge amount is set for all the nozzles 21.

[0108] 22 and 23, only the abnormal nozzle 21N constituting the contact nozzle group NG1 is set as the first nozzle FN1 that is the target of the first dummy discharge. In other words, the abnormal nozzle 21N is identified as the first nozzle FN1 that is the target of the first dummy discharge that discharges liquid at a first dummy discharge amount, and the normal nozzle 21G is identified as the second nozzle FN2 that is the target of the second dummy discharge that discharges liquid at a second dummy discharge amount. Note that the process of step S17 set by the method of this first embodiment corresponds to "setting the first discharge amount, which is the dummy discharge amount from the nozzle detected by the detection unit, to be greater than the second discharge amount, which is the dummy discharge amount from the other nozzles."

[0109] In the second embodiment shown in FIG. 24 and FIG. 25, the abnormal nozzle 21N and the normal nozzles 21G of the predetermined number a adjacent to the abnormal nozzle 21N are set as the first nozzles FN1 to be subjected to the first blank discharge. In this way, by identifying the color mixing prevention compatible nozzle, the color mixing prevention compatible nozzle (first nozzle FN1) to which the first blank discharge amount is set and the other normal nozzles 21G (second nozzle FN2) to which the second blank discharge amount is set are set for all the nozzles 21. In other words, the first blank discharge amount or the second blank discharge amount is set for all the nozzles 21. The process of step S17 set by the method of this second embodiment corresponds to "setting the first discharge amount, which is the blank discharge amount from the nozzle detected by the detection unit 106 and the predetermined number a adjacent nozzles adjacent to the nozzle, to be larger than the second discharge amount, which is the blank discharge amount from the other nozzles." Furthermore, the process of step S17 set by the method of the second embodiment corresponds to "setting the predetermined number a to a larger number as the number A of consecutively adjacent nozzles detected by the detection unit 106 increases." Here, the "number A of consecutively adjacent nozzles" may include a misdetected nozzle nf in which only one nozzle 21 is not detected and is missing from the contact nozzle group NG1 detected by the detection unit 106.

[0110] In the third embodiment shown in Figs. 26 and 27, when the number of normal nozzles 21G located between a plurality of contact nozzle groups NG1 in contact with a plurality of adhering liquids WL is equal to or less than a specified number K, the normal nozzle 21G located F1 consecutively adjacent from the abnormal nozzle 21N is identified as the first nozzle FN1. F1 is set to be f1 more than the specified number a in the second embodiment (F1=a+f1). Note that the process of step S17 set by the method of the third embodiment corresponds to "when a plurality of contact nozzle groups are detected by the detection unit, if the number of nozzles between the plurality of contact nozzle groups is equal to or less than a specified number, set the amount of idling from the nozzles between the plurality of contact nozzle groups to be greater than the amount of idling from each nozzle other than the contact nozzle groups."

[0111] In step S18, the control unit 100 executes a first blank discharge from the color mixing prevention nozzle (first nozzle FN1) and a second blank discharge from the other normal nozzles 21G (second nozzle FN2). The first discharge amount, which is the discharge amount of the first blank discharge, is a discharge amount that can discharge the color mixed liquid WL from inside the nozzle 21, and is greater than the second discharge amount, which is the discharge amount of the second blank discharge, which is a normal blank discharge. Note that the process of step S18 corresponds to "performing blank discharge, which is the discharge of liquid unrelated to recording, from a plurality of nozzles based on the set blank discharge amount."

[0112] If it is determined in step S16 that there is no contact nozzle group, in step S19, the control unit 100 executes the second dummy discharge from all the nozzles. That is, dummy discharge is performed from all the nozzles 21 with the second dummy discharge amount that is smaller than the first dummy discharge amount.

[0113] <Effects of the embodiment> (1) The liquid ejection device 11 includes a liquid ejection unit 20, a pressurizing unit 66, a wiping unit 76, and a detection unit 106. The liquid ejection unit 20 is configured to be capable of recording by ejecting liquid from a plurality of nozzle groups N1 to N4 formed on the nozzle surface 28. The pressurizing unit 66 is configured to be capable of pressurizing the liquid in the plurality of nozzle groups N1 to N4, thereby causing the liquid to swell from the plurality of nozzle groups N1 to N4. The wiping unit 76 is configured to be capable of wiping the nozzle surface 28. The detection unit 106 is configured to be capable of detecting the nozzles 21 that are in contact with droplets adhering to the nozzle surface 28. A control method for the liquid ejection device 11 includes the following (a) to (e). (a) Pressurizing the pressurizing unit 66 causes the liquid to swell from the multiple nozzle groups N1 to N4. (b) While the operation of the pressure applying unit 66 is being maintained, wiping of the nozzle surface 28 by the wiping unit 76 and detection by the detection unit 106 are performed. (c) Setting the idle discharge amount of each of the plurality of nozzles 21 constituting the plurality of nozzle groups N1 to N4 based on the detection result by the detection unit 106. (d) Releasing the pressure from the pressure applying unit 66 . (e) Performing dummy ejection, which is ejection of liquid unrelated to recording, from the multiple nozzles 21 based on the set dummy ejection amount. According to this method, the amount of idle discharge for preventing color mixing can be set according to the state of each nozzle 21, so that unnecessary discharge of liquid from the nozzles 21 can be suppressed.

[0114] (2) The control method of the liquid ejection device 11 includes setting a first ejection amount, which is the amount of idling ejection from the nozzle 21 detected by the detection unit 106, to be greater than a second ejection amount, which is the amount of idling ejection from the other nozzles 21. According to this method, the amount of idling ejection from the nozzle 21 where color mixing is estimated to occur is increased, so that color mixing can be suppressed with an overall small amount of idling ejection.

[0115] (3) The control method of the liquid ejection device 11 includes setting a first ejection amount, which is the amount of idling ejection from the nozzle 21 detected by the detection unit 106 and a predetermined number of nozzles 21 adjacent to the nozzle 21, to be greater than a second ejection amount, which is the amount of idling ejection from the other nozzles 21. According to this method, the amount of idling ejection is increased for nozzles 21 where color mixing may occur, so that color mixing can be further suppressed with an overall small amount of idling ejection.

[0116] (4) The method for controlling the liquid ejection device 11 includes setting the predetermined number to a larger number as the number of consecutively adjacent nozzles 21 detected by the detection unit 106 increases. According to this method, the greater the number of consecutively adjacent nozzles 21 detected by the detection unit 106, the greater the possibility of color mixing among more nozzles 21 in the vicinity. By taking this into consideration, color mixing can be further suppressed.

[0117] (5) The nozzles 21 that come into contact with one droplet adhering to the nozzle surface 28 are designated as contact nozzle group NG1. The control method of the liquid ejection device 11 includes, when multiple contact nozzle groups NG1 are detected by the detection unit 106, setting the amount of idling from the nozzles 21 between the multiple contact nozzle groups NG1 to be greater than the amount of idling from each nozzle 21 other than the contact nozzle group NG1 if the number of nozzles 21 between the multiple contact nozzle groups NG1 is equal to or less than a specified number. According to this method, the amount of idling is increased for nozzles 21 where color mixing may occur, so that color mixing can be further suppressed with an overall small amount of idling.

[0118] (6) The liquid ejection device 11 includes a liquid ejection unit 20, a pressurizing unit 66, a wiping unit 76, a detection unit 106, and a control unit 100. The liquid ejection unit 20 is configured to be capable of recording by ejecting liquid from a plurality of nozzle groups N1 to N4 formed on the nozzle surface 28. The pressurizing unit 66 is configured to be capable of pressurizing the liquid in the plurality of nozzle groups N1 to N4, thereby causing the liquid to swell from the plurality of nozzle groups N1 to N4. The wiping unit 76 is configured to be capable of wiping the nozzle surface 28. The detection unit 106 is configured to be capable of detecting the nozzle 21 that is in contact with the droplets adhering to the nozzle surface 28. The control unit 100 causes the liquid to swell from the plurality of nozzle groups N1 to N4 by applying pressure from the pressurizing unit 66. In addition, the control unit 100 causes the wiping unit 76 to wipe the nozzle surface 28 and the detection unit 106 to perform detection while maintaining the operation of the pressurizing unit 66 during pressurization. Furthermore, the control unit 100 sets the dummy discharge amount for each of the nozzles 21 constituting the nozzle groups N1 to N4 based on the detection result by the detection unit 106. Then, the control unit 100 releases the pressure of the pressurizing unit 66. Furthermore, the control unit 100 performs dummy discharge, which is the discharge of liquid unrelated to recording, from the nozzles 21 based on the set dummy discharge amount. With this configuration, it is possible to set the dummy discharge amount for preventing color mixing according to the state of each nozzle 21, so that it is possible to suppress the discharge of unnecessary liquid from the nozzles 21.

[0119] (7) The liquid ejection unit 20 has a plurality of actuators 200 provided corresponding to a plurality of nozzles 21 constituting a plurality of nozzle groups N1 to N4, and a plurality of vibration plates 265. The plurality of actuators 200 are individually driven by a head driving circuit 110, which is an example of a driving circuit, to partially displace the plurality of vibration plates 265. The displaced vibration plate 265 ejects liquid from the nozzle 21 corresponding to the driven actuator 200. The detection unit 106 detects the nozzle 21 with which the droplets adhering to the nozzle surface 28 come into contact, based on the residual vibration of the displaced vibration plate 265. According to this configuration, the detection unit 106, which detects ejection failure of the nozzle 21 using components of the liquid ejection unit 20, is used to detect the nozzle 21 with which the droplets adhering to the nozzle surface 28 come into contact, so there is no need to provide another detection unit 106.

[0120] (8) The pressurizing unit 66 has a liquid chamber 95, an on-off valve 63, and a drive unit 67. The liquid chamber 95 is provided in the middle of the supply flow path 25 that supplies liquid to the liquid ejection unit 20, and is configured so that the volume can be changed by the displacement of a membrane member 97. The on-off valve 63 is provided upstream of the liquid chamber 95 in the supply flow path 25, and is configured so that the supply flow path 25 can be opened and closed. The drive unit 67 is configured so that the membrane member 97 can be displaced. With the supply flow path 25 closed by the on-off valve 63, the control unit 100 displaces the membrane member 97 by the drive unit 67 in a direction that reduces the volume of the liquid chamber 95, thereby causing the liquid to swell from the multiple nozzle groups N1 to N4. With this configuration, it is possible to cause the liquid to swell from the nozzles 21 with a simple configuration.

[0121] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0122] The multiple nozzles 21 constituting one nozzle group are each connected to the reservoir 272 through the cavity 264 and the liquid supply port 271. Therefore, as in the third embodiment, when multiple adhered liquids WL come into contact with the nozzle surface 28, the smaller adhered liquids WL may be pulled into the nozzle 21 by the force of the larger adhered liquids WL tending to hang down due to gravity. When such a phenomenon occurs, the detection unit 106 may not be able to detect the presence of the smaller adhered liquid WL.

[0123] Therefore, if the detection unit 106 detects even one nozzle 21 having the adhering liquid WL attached thereto, a first dummy ejection at the first ejection volume may be performed for all of the multiple nozzles 21 that are connected to the nozzle 21 detected as having the adhering liquid WL attached thereto via the reservoir 272.

[0124] Furthermore, if there is another nozzle group adjacent to the nozzle group including the nozzle 21 in which the adhering liquid WL has been detected, there is a possibility that the same phenomenon is occurring in that nozzle group, so the first dummy ejection at the first ejection volume may also be performed on all of the multiple nozzles 21 that make up the other adjacent nozzle group.

[0125] When the detection unit 106 is configured to detect the nozzle 21 with which the adhering liquid WL is in contact based on the residual vibration of the displaced vibration plate 265, it can also detect the presence of air bubbles in the liquid in the nozzle 21 or cavity 264.

[0126] When the detection unit 106 detects whether or not there is a nozzle 21 in contact with the adhering liquid WL, if it detects the presence of an air bubble in the nozzle 21 or the cavity 264, the residual vibration may be affected by the air bubble, and there is a possibility that the nozzle 21 in contact with the adhering liquid WL may not be detected correctly.

[0127] Therefore, when the detection unit 106 detects whether or not there is a nozzle 21 in contact with the adhering liquid WL, if a nozzle 21 or cavity 264 in which an air bubble is present is detected, a first blank ejection may be performed with the first ejection amount for all of the multiple nozzles 21 that are connected via the reservoir 272 to the nozzle 21 or cavity 264 in which the air bubble is detected.

[0128] Furthermore, if there is another nozzle group adjacent to the nozzle group including the nozzle 21 or cavity 264 in which an air bubble has been detected, the same phenomenon may be occurring in that nozzle group, so the first dummy ejection with the first ejection amount may also be performed for all of the nozzles 21 constituting the other adjacent nozzle group. To be even more on the safe side, the first dummy ejection with the first ejection amount may also be performed for all of the nozzles 21 in the head (unit ejection head 27 or liquid ejection head 22) in which the presence of an air bubble has been detected.

[0129] The setting of the idle discharge amount based on the detection result of the detection unit 106 (step S17) and the release of the pressure of the pressure unit 66 may be performed in any order, or may be performed simultaneously. However, the other operations are performed in the order of the steps in FIG.

[0130] The detection of the nozzles that come into contact with the liquid IL adhering to the nozzle surface 28 is not limited to the configuration of detecting the residual vibration of the vibration plate 265, and other detection methods may be used. For example, in the above embodiment, the detection unit 106 used for nozzle inspection is used, but an imaging method may also be used. In the imaging method, the nozzles 21 that come into contact with the liquid adhering to the nozzle surface 28 are detected by image analysis processing that analyzes an image of the nozzle surface 28 captured by a camera.

[0131] In the second embodiment, the predetermined number a was set to a larger value as the number A of consecutively adjacent nozzles detected by the detection unit 106 increased, but the predetermined number a may be set to a constant value regardless of the number A of consecutively adjacent nozzles detected by the detection unit 106.

[0132] Instead of a configuration including a selector valve 69 or the like that utilizes air pressure to change the membrane member 97 and pressurize the liquid in the liquid chamber 95, causing the liquid to swell from the nozzle 21, the drive unit 67 may be a motor that drives a pressurizing member (e.g., a piston) that pressurizes the liquid in the liquid chamber 95, or a pump that sends the liquid in the supply flow path 25 downstream to cause the liquid to swell from the nozzle 21. The drive unit 67 may also include an air cylinder, a cam, or a solenoid.

[0133] In the above embodiment, the on-off valve 63 may be eliminated. For example, a check valve or a throttle may be provided in place of the on-off valve 63. It is only necessary that the valve be capable of closing to prevent the liquid in the liquid chamber 95 from flowing upstream when the head tank 64 is moved from the non-pressurized position to the pressurized position, or that a resistance be provided to reduce the amount of liquid flowing upstream.

[0134] The wiping portion 76 is not limited to a blade type having the wiper blade 77, and may be a cloth wiper. The liquid ejection device 11 is not limited to an inkjet printer that ejects liquid such as ink onto a medium M such as paper, but may be a textile printing device that ejects liquid such as ink onto fabric.

[0135] The liquid ejection device 11 is not limited to a line printer, and may be a serial printer or a page printer. For example, in the case of a serial printer, the liquid ejection unit 20 is composed of a carriage that can move back and forth along the width direction X, and a liquid ejection head 22 provided on the carriage. Then, printing is performed on the medium M by alternately performing a transport operation that transports the medium M to the next printing position and a printing operation that ejects liquid droplets from the nozzles 21 of the liquid ejection head 22 during the movement of the carriage.

[0136] The liquid ejection device 11 may not include the image reading unit 13 and may be a printer having only a printing function. The liquid may be something other than ink. For example, it may be a coating liquid or a cleaning liquid.

[0137] The liquid ejection device 11 is not limited to a printing device that ejects ink as an example of liquid. The liquid ejection device 11 may eject liquids other than ink. The state of the liquid ejected from the liquid ejection device 11 as droplets includes granular, teardrop, and thread-like tails. The liquid here may be any material that can be ejected from the liquid ejection device 11. For example, the liquid may be any state in which a substance is in a liquid phase, and includes fluids such as high or low viscosity liquids, sols, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, and liquid metals (metal melts). The liquid includes not only liquids as one state of matter, but also particles of functional materials made of solids such as pigments and metal particles dissolved, dispersed, or mixed in a solvent. Representative examples of liquids include inks and liquid crystals as described in the above embodiment. Here, the ink includes 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 the liquid ejection device 11 include devices that eject liquids containing materials such as electrode materials and color materials in a dispersed or dissolved form, which are used in the manufacture of liquid crystal displays, EL (electroluminescence) displays, surface-emitting displays, and color filters. The liquid ejection device 11 may be a device that ejects bioorganic matter used in the manufacture of biochips, a device that ejects liquids used as a precision pipette to serve as samples, a textile printing device, a microdispenser, or the like. The liquid ejection device 11 may be a device that ejects lubricating oil at a pinpoint onto precision machinery such as watches and cameras, or a device that ejects transparent resin liquid such as ultraviolet curing resin onto a substrate to form a minute hemispherical lens (optical lens) used in optical communication elements, or the like. The liquid ejection device 11 may be a device that ejects an etching liquid such as an acid or alkali to etch a substrate, or the like. Furthermore, the liquid ejection device 11 may be a three-dimensional printer.

[0138] The technical ideas and effects derived from the above-described embodiment and modified examples will be described below. (A) A method for controlling a liquid ejection device includes a liquid ejection unit capable of recording by ejecting liquid from a plurality of nozzle groups formed on a nozzle surface, a pressurizing unit capable of pressurizing the liquid in the plurality of nozzle groups to cause the liquid to swell from the plurality of nozzle groups, a wiping unit capable of wiping the nozzle surface, and a detection unit capable of detecting a nozzle with which a droplet adhering to the nozzle surface comes into contact, the method includes: causing the liquid to swell from the plurality of nozzle groups by the pressurization of the pressurizing unit; wiping the nozzle surface by the wiping unit and detection by the detection unit while maintaining the operation of the pressurizing unit at the time of the pressurization; setting an amount of blank ejection for each of the plurality of nozzles constituting the plurality of nozzle groups based on the detection result by the detection unit; releasing the pressurization of the pressurizing unit; and performing blank ejection, which is ejection of liquid unrelated to the recording, from the plurality of nozzles based on the set amount of blank ejection. According to this method, it is possible to set an amount of blank ejection for preventing color mixing according to the state of each nozzle, thereby suppressing the discharge of unnecessary liquid from the nozzles.

[0139] (B) The method of controlling the liquid ejection device described in (A) above may include setting a first ejection amount, which is an amount of idling ejection from the nozzle detected by the detection unit, to be greater than a second ejection amount, which is an amount of idling ejection from the other nozzles. According to this method, the amount of idling ejection from the nozzle estimated to cause color mixing is increased, so that color mixing can be suppressed with an overall small amount of idling ejection.

[0140] (C) The method of controlling a liquid ejection device described in (A) or (B) above may include setting a first ejection amount, which is an amount of blank ejection from a nozzle detected by the detection unit and a predetermined number of adjacent nozzles in succession from the nozzle, to be greater than a second ejection amount, which is an amount of blank ejection from the other nozzles. According to this method, the amount of blank ejection is increased for nozzles where color mixing may occur, so that color mixing can be further suppressed with an overall small amount of blank ejection.

[0141] (D) The method for controlling a liquid ejection device according to any one of (A) to (C) above may include setting the predetermined number to a larger number as the number of consecutively adjacent nozzles detected by the detection unit increases. According to this method, the greater the number of consecutively adjacent nozzles detected by the detection unit, the greater the possibility of color mixing in more nozzles in the vicinity. By taking this into consideration, color mixing can be further suppressed.

[0142] (E) The method of controlling a liquid ejection device according to any one of (A) to (D) above may include: setting a nozzle that comes into contact with one droplet adhering to the nozzle face as a contact nozzle group; and when the detection unit detects a plurality of the contact nozzle groups, if the number of nozzles between the plurality of contact nozzle groups is equal to or less than a specified number, setting an amount of blank ejection from the nozzles between the plurality of contact nozzle groups to be greater than an amount of blank ejection from each nozzle other than the contact nozzle group. According to this method, the amount of blank ejection is increased for nozzles where color mixing may occur, so that color mixing can be further suppressed with an overall small amount of blank ejection.

[0143] (F) A liquid ejection device includes a liquid ejection section capable of recording by ejecting liquid from a plurality of nozzle groups formed on a nozzle surface, a pressurizing section capable of pressurizing the liquid in the plurality of nozzle groups to cause the liquid to swell from the plurality of nozzle groups, a wiping section capable of wiping the nozzle surface, a detection section capable of detecting nozzles in contact with droplets adhering to the nozzle surface, and a control section, and the control section causes the liquid to swell from the plurality of nozzle groups by the pressurization of the pressurizing section, wipes the nozzle surface with the wiping section and performs detection with the detection section while maintaining the operation of the pressurizing section during the pressurization, sets an amount of blank ejection for each of the plurality of nozzles constituting the plurality of nozzle groups based on the detection result by the detection section, releases the pressurization of the pressurizing section, and performs blank ejection, which is ejection of liquid unrelated to the recording, from the plurality of nozzles based on the set amount of blank ejection. With this configuration, it is possible to set an amount of blank ejection for preventing color mixing according to the state of each nozzle, thereby suppressing wasteful discharge of liquid from the nozzles.

[0144] (G) In the liquid ejection device described in (F) above, the liquid ejection unit may have a plurality of actuators provided corresponding to the plurality of nozzles constituting the plurality of nozzle groups, and a plurality of vibration plates, the plurality of actuators being individually driven by a drive circuit to partially displace the plurality of vibration plates, the displaced vibration plates causing the liquid to be ejected from the nozzles corresponding to the driven actuators, and the detection unit may detect the nozzles that are in contact with the droplets adhering to the nozzle face based on the residual vibration of the displaced vibration plate. According to this configuration, the detection unit that detects nozzle ejection defects by utilizing components of the liquid ejection unit is used to detect the nozzles that are in contact with the droplets adhering to the nozzle face, so there is no need to provide an additional detection unit.

[0145] (H) In the liquid ejection device described in (F) or (G) above, the pressurizing unit may have a liquid chamber that is provided in the middle of a supply flow path that supplies liquid to the liquid ejection unit and whose volume can be changed by displacing a membrane member, an on-off valve that is provided upstream of the liquid chamber in the supply flow path and can open and close the supply flow path, and a drive unit that can displace the membrane member, and the control unit may close the supply flow path with the on-off valve and displace the membrane member with the drive unit in a direction that reduces the volume of the liquid chamber, thereby expanding the liquid from the multiple nozzle groups. With this configuration, it is possible to expand the liquid from the nozzles with a simple configuration. [Explanation of symbols]

[0146] 11...liquid ejection device, 12...device body, 13...image reading device, 14...automatic feed device, 15...operation unit, 16...medium storage unit, 17...stacker, 18...casing, 19...size detection unit, 20...liquid ejection unit, 21,KN,CN,MN,YN... nozzle, 21N... abnormal nozzle, 21G... normal nozzle, 22... liquid ejection head, 23... support part, 24... liquid container, 24A... liquid pack, 24B... case, 25... supply flow path, 26... holder, 27... unit ejection head, 28... nozzle surface, 29... check valve, 30... transport part, 31... feed roller, 33... transport roller, 34... transport belt, 37... support part movement mechanism, 40... maintenance part, 41... cap, 42... waste liquid flow path, 43... pressure reduction unit, 44... discharge mechanism, 45... cap movement mechanism, 50... waste liquid container, 51... 3. A pressurizing unit, comprising: a pressure sensor, a selector valve, a pressure sensor, and a pressure sensor arranged to detect a pressure change of the pressure sensor ... 91...liquid chamber, 91a...bottom surface, 92...air chamber, 93...membrane member, 94...operating pressure adjustment spring, 95...liquid chamber, 95a...bottom surface, 96...air chamber, 97...membrane member, 98...operating pressure adjustment spring, 100...control unit, 101...computer, 102...printing control unit, 103...nozzle inspection unit, 105...storage unit, 106...detection unit, 110...head drive circuit as an example of a drive circuit, 111...drive signal generation unit, 112...ejection abnormality detection unit, 113...switching unit, 130...ejection unit, 200...actuator, 201...lower electrode, 202...upper electrode, 2 03...piezoelectric body, 264...cavity, 265...vibration plate, 266...cavity plate, 271...liquid supply port, reservoir 272, N1 to N4...nozzle group, SL...solenoid, M...medium, IL...liquid, WL...adhering liquid (mixed color liquid), MS...meniscus, EL...bulge, D...ejection section, Vin...driving signal, SI...path data, COM...driving waveform signal, Vout...residual vibration signal, NG1...contact nozzle group, FN1...first nozzle, FN2...second nozzle, a...predetermined number, K...predetermined number, X...width direction, Y...transport direction, Z...vertical direction. ,

Claims

1. a liquid ejection unit capable of recording by ejecting liquid from a plurality of nozzle groups formed on a nozzle surface; a pressurizing unit capable of pressurizing the liquid in the plurality of nozzle groups to cause the liquid to swell out of the plurality of nozzle groups; a wiping unit capable of wiping the nozzle surface; a detection unit capable of detecting a nozzle that is in contact with a droplet adhering to the nozzle surface, causing the liquid to swell from the plurality of nozzle groups by the pressurization of the pressurizing unit; wiping the nozzle surface by the wiping unit and detecting the nozzle surface by the detecting unit while maintaining the operation of the pressing unit; setting an idle discharge amount for each of a plurality of nozzles constituting a plurality of nozzle groups based on a detection result by the detection unit; Releasing the pressure applied by the pressure applying unit; performing a dummy discharge, which is a discharge of liquid unrelated to the recording, from the plurality of nozzles based on the set dummy discharge amount; A method for controlling a liquid ejection device, comprising:

2. setting a first discharge amount, which is an amount of dummy discharge from the nozzle detected by the detection unit, to be greater than a second discharge amount, which is an amount of dummy discharge from the other nozzles; The method for controlling a liquid ejection device according to claim 1 , further comprising:

3. setting a first discharge amount, which is an amount of blank discharge from the nozzle detected by the detection unit and a predetermined number of nozzles adjacent to the nozzle, to be larger than a second discharge amount, which is an amount of blank discharge from the other nozzles; The method for controlling a liquid ejection device according to claim 1 , further comprising:

4. the predetermined number is set to a larger number as the number of consecutive adjacent nozzles detected by the detection unit increases; The method for controlling a liquid ejection device according to claim 3 , further comprising:

5. a nozzle that comes into contact with one droplet adhering to the nozzle surface is defined as a contact nozzle group, and when a plurality of the contact nozzle groups are detected by the detection unit, if the number of nozzles between the plurality of contact nozzle groups is equal to or less than a specified number, the amount of blank discharge from the nozzles between the plurality of contact nozzle groups is set to be greater than the amount of blank discharge from each nozzle other than the contact nozzle group; 5. The method for controlling a liquid ejection device according to claim 3, further comprising:

6. a liquid ejection unit capable of recording by ejecting liquid from a plurality of nozzle groups formed on a nozzle surface; a pressurizing unit capable of pressurizing the liquid in the plurality of nozzle groups to cause the liquid to swell out of the plurality of nozzle groups; a wiping unit capable of wiping the nozzle surface; a detection unit capable of detecting a nozzle that is in contact with droplets adhering to the nozzle surface; A control unit, The control unit is the liquid is caused to swell from the plurality of nozzle groups by the pressurization of the pressurizing unit; While maintaining the operation of the pressurizing unit during the pressurization, the wiping unit wipes the nozzle surface and the detection unit detects the nozzle surface. setting an idle discharge amount for each of the plurality of nozzles constituting the plurality of nozzle groups based on the detection result by the detection unit; The pressure applied by the pressure applying unit is released, A liquid ejection apparatus comprising: a plurality of nozzles that ejects liquid unrelated to the recording, the plurality of nozzles ejecting the liquid based on the set amount of the idle ejection.

7. the liquid ejection unit includes a plurality of actuators provided corresponding to a plurality of nozzles constituting a plurality of the nozzle groups, and a plurality of vibration plates; the actuators are individually driven by a drive circuit to partially displace the vibration plates; The displaced vibration plate ejects the liquid from the nozzle corresponding to the driven actuator, 7. The liquid ejection device according to claim 6, wherein the detection section detects the nozzle with which the liquid droplets adhering to the nozzle face come into contact, based on residual vibration of the displaced vibration plate.

8. The pressure applying unit is a liquid chamber that is provided in a supply flow path that supplies liquid to the liquid discharge portion, the volume of which can be changed by displacement of a membrane member; an on-off valve provided in the supply flow passage upstream of the liquid chamber and capable of opening and closing the supply flow passage; a driving unit capable of displacing the membrane member; The control unit displaces the film member in a direction in which the volume of the liquid chamber decreases by the drive unit while the on-off valve closes the supply flow path, thereby causing the liquid to swell from the plurality of nozzle groups.

7. The liquid ejection device according to claim 6.

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