Method for controlling liquid ejecting apparatus and liquid ejecting apparatus

Abstract

The invention provides a control method of a liquid ejecting apparatus and the liquid ejecting apparatus. A liquid ejecting apparatus includes a liquid ejecting section, a pressurizing section, a wiping section, and a detecting section. The pressurizing unit causes the liquid to blow out from the plurality of nozzles by pressurizing. The detection unit detects a nozzle in contact with a droplet adhering to the nozzle surface. The control method of the liquid ejecting apparatus includes the following steps: pressurizing by a pressurizing part to enable liquid to blow out from a plurality of nozzle groups; a wiping unit that wipes the nozzle surface by the wiping unit and detects the nozzle surface by the detection unit in a state in which the operation during pressurization is maintained; an empty discharge amount setting unit that sets an empty discharge amount for each of the plurality of nozzles on the basis of a detection result detected by the detection unit; releasing the pressurization of the pressurizing part; on the basis of the set empty discharge amount, empty discharge is performed from the plurality of nozzles.

Description

Technical Field

[0001] The present invention relates to a control method of a liquid ejection device having a liquid ejection portion for ejecting liquid, and the liquid ejection device. Background Art

[0002] Patent document 1 discloses a liquid ejection device having a head unit (an example of a liquid ejection unit) for ejecting liquid. The liquid ejection device comprises: a liquid storage body for storing liquid; a liquid ejection head for ejecting liquid; and a supply flow path for supplying liquid from the liquid storage body to the liquid ejection head. In addition, in order to discharge ink of other colors sucked from the nozzles due to wiping, etc., an empty ejection (flushing) of ejecting ink from all nozzles of the head unit is performed.

[0003] However, since all nozzles are uniformly subjected to empty ejection (flushing) in order to prevent color mixing, the amount of liquid such as ink discharged from the nozzles is increased in vain without setting the empty ejection amount according to the state of each nozzle. Therefore, there is a problem of suppressing the amount of liquid that is discharged in vain from the nozzle due to empty ejection. In addition, the same problem also exists in liquid ejection devices that are not limited to printers that eject ink, and eject liquids other than ink.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-14264 Summary of the invention

[0005] In a control method for a liquid ejection device for solving the above-mentioned problem, the liquid ejection device comprises: a liquid ejection unit capable of performing 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 so that the liquid bulges out from the plurality of nozzle groups; a wiping unit capable of wiping the nozzle surface; and a detection unit capable of detecting nozzles contacted by droplets attached to the nozzle surface. The control method for the liquid ejection device comprises the following contents, namely: the liquid bulges out from the plurality of nozzle groups by the pressurizing of the pressurizing unit; wiping the nozzle surface by the wiping unit and detecting by the detection unit are performed while the operation of the pressurizing unit is maintained; setting an empty ejection amount of each of the plurality of nozzles constituting the plurality of nozzle groups based on the detection result detected by the detection unit; releasing the pressurizing of the pressurizing unit; and performing ejection of liquid not related to the recording, i.e., empty ejection, from the plurality of nozzles based on the set empty ejection amount.

[0006] A liquid ejection device for solving the above-mentioned problems comprises: a liquid ejection unit capable of performing 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 so that the liquid bulges out from the plurality of nozzle groups; a wiping unit capable of wiping the nozzle surface; a detection unit capable of detecting nozzles in contact with liquid droplets attached to the nozzle surface; and a control unit, wherein the control unit performs the following control, i.e., the liquid bulges out from the plurality of nozzle groups by the pressurizing of the pressurizing unit, the nozzle surface is wiped by the wiping unit and the detection by the detection unit is performed while the operation of the pressurizing unit is maintained, the empty ejection amount of each of the plurality of nozzles constituting the plurality of nozzle groups is set based on the detection result detected by the detection unit, the pressurizing of the pressurizing unit is released, and based on the set empty ejection amount, the liquid ejection not related to the recording, i.e., empty ejection, is performed from the plurality of nozzles. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a perspective view showing the liquid ejecting device in the embodiment.

[0008] Figure 2 A schematic front cross-sectional view showing the internal structure of the liquid ejecting device.

[0009] Figure 3 It is a schematic diagram showing the liquid ejection mechanism and the maintenance section.

[0010] Figure 4 This is a bottom view of the liquid ejection head.

[0011] Figure 5 It is a schematic bottom view showing the nozzle arrangement and the wiping portion of the liquid ejecting head.

[0012] Figure 6 It is a schematic front view partially cut away showing the pressurizing portion when the on-off valve is closed.

[0013] Figure 7 It is a schematic front view partially cut away showing the pressurizing portion in the pressurizing position.

[0014] Figure 8 It is a partially cutaway schematic front view showing the pressurizing portion in the pressurizing position in a state where the on-off valve is open.

[0015] Fig. 9 It is a partially cutaway schematic front view showing the pressurizing portion with the on-off valve in the pressurization release position.

[0016] Fig.10 This is a schematic cross-sectional view showing the state of liquid in the nozzle during printing.

[0017] Fig.11 A schematic cross-sectional view showing liquid bulging out of a nozzle when pressurized.

[0018] Fig.12 It is a schematic cross-sectional view showing the liquid in the nozzle during wiping.

[0019] Fig.13 It is a schematic cross-sectional view showing the liquid in the nozzle when the pressurization is released.

[0020] Fig.14 This is a schematic cross-sectional view showing the state of the mixed color liquid remaining on the nozzle surface after wiping.

[0021] Fig.15 This is a schematic cross-sectional view showing a state where the color mixing liquid is sucked into the nozzle.

[0022] Fig.16 It is a cross-sectional view showing the structure of the ejection portion.

[0023] Fig.17 A block diagram showing the electrical structure of a liquid ejection device.

[0024] Fig.18 This is a block diagram showing the electrical structure involved in discharge abnormality detection.

[0025] Fig.19 This is a circuit diagram showing an equivalent circuit related to discharge abnormality detection.

[0026] Fig. 20 It is a graph showing the relationship between the residual vibration signal and the discharge abnormality.

[0027] Fig.21 This is a graph showing the detection results of the nozzle inspection unit after wiping.

[0028] Fig. 22 1 is a schematic cross-sectional view of a liquid ejection head showing a first nozzle to be subjected to first idle ejection in the first embodiment.

[0029] Fig.23 1 is a schematic cross-sectional view of a liquid ejection head showing a first nozzle to be subjected to first idle ejection.

[0030] Fig.24 1 is a schematic cross-sectional view showing a liquid ejection head of a first nozzle serving as a target of first idle ejection in the second embodiment.

[0031] Fig.25 1 is a schematic cross-sectional view of a liquid ejection head showing a first nozzle to be subjected to first idle ejection.

[0032] Fig.261 is a schematic cross-sectional view showing a liquid ejection head of a first nozzle serving as a target of first idle ejection in the third embodiment.

[0033] Fig. 27 1 is a schematic cross-sectional view of a liquid ejection head showing a first nozzle to be subjected to first idle ejection.

[0034] Fig.28 is a flowchart showing a maintenance control routine. DETAILED DESCRIPTION

[0035] Hereinafter, a liquid ejection device and a control method thereof according to an embodiment will be described with reference to the drawings. Figure 1 The liquid ejection device 11 shown is an inkjet printer that ejects ink, which is an example of liquid, onto a medium M such as paper to perform recording. Figure 1 In the figure, the liquid ejection device 11 is placed on a horizontal plane, the Z axis represents the direction of gravity, and the X axis and the Y axis represent the direction along the horizontal plane. The X axis, the Y axis, and the Z axis are orthogonal to each other.

[0036] like Figure 1 As shown in the figure, the liquid ejection device 11 may include a device body 12, an image reading unit 13 for reading an image of a manuscript, and an automatic feeding device 14 for sending the manuscript to the image reading unit 13. The liquid ejection device 11 may include an operation unit 15 for a user to give instructions to the liquid ejection device 11 and to be operated, a medium storage unit 16 capable of storing a medium M such as paper, and a stacker 17 for receiving the medium M discharged after printing. The operation unit 15 may be, for example, a touch panel or a button, or a combination thereof. The medium storage unit 16 may store a plurality of media M in a stacked state. The liquid ejection device 11 may include a plurality of medium storage units 16.

[0037] Next, refer to Figure 2 , the internal structure of the liquid ejection device 11 is described. Figure 2 As shown, the device body 12 has a substantially rectangular parallelepiped housing 18. The liquid ejection device 11 includes a liquid ejection unit 20, a conveying unit 30 for conveying a medium M, a maintenance unit 40 for performing maintenance on the liquid ejection head 22, and a control unit 100 for controlling the components including these devices in the housing 18.

[0038] The liquid ejection unit 20 includes a liquid ejection head 22 having a plurality of nozzles 21 that can eject liquid droplets, and a support unit 23 that holds the liquid ejection head 22 at a predetermined height. The plurality of nozzles 21 are opened on a nozzle surface 28 that is a surface (e.g., bottom surface) in the liquid ejection head 22 that is opposite to a conveying path through which the medium M is conveyed.

[0039] The liquid ejection head 22 ejects liquid toward the medium M. When the position where the liquid ejection head 22 ejects liquid is set as the recording position, printing is performed by ejecting liquid from the nozzle 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 that can simultaneously eject liquid across the entire width area of ​​the medium M in the width direction X that intersects (orthogonal in this embodiment) the conveying 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 opposite to the entire width area of ​​the medium M conveyed at a fixed speed corresponding to the printing mode.

[0040] The liquid ejection head 22 is supported by the support portion 23 in a state extending in the width direction X intersecting the conveying direction Y of the medium M. The liquid ejection head 22 is configured to eject liquid from a plurality of nozzles 21 constituting a plurality of nozzle groups toward the medium M. A supply flow channel 25 for supplying liquid to the liquid container 24 is connected to the liquid ejection head 22. A plurality of liquid containers 24 are mounted on a retaining frame 26 in the housing 18.

[0041] The plurality of liquid containers 24 respectively store different types of liquids. In the example where the liquid is ink, the plurality of liquid containers 24 respectively store inks of different colors. In this example, the plurality of liquid containers 24 respectively store black ink and color inks. In the plurality of liquid containers 24, inks of various colors, such as black, yellow, cyan, and magenta, are respectively stored. That is, the plurality of 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. In addition, for the black liquid container 24K, since the ink consumption is relatively large, it can be used as Figure 2 As shown in the example, a plurality of (for example, two) liquid containers may be installed, and the volume may be larger than that of other ink colors. Figure 2 The five examples shown can be appropriately changed according to the number of ink colors, and may be 6 to 10 or 1 to 4.

[0042] The liquid storage body 24 is, for example, a liquid box detachably mounted on the holder 26, but may also be a liquid tank. In the case of a liquid tank, the liquid may be replenished by the user by injecting liquid from a container such as a bottle.

[0043] The conveying unit 30 includes a feed roller 31 that feeds the medium M one by one from the top of the group of media M stacked in the medium storage unit 16, and a separation roller 32 that separates the medium M one by one. Furthermore, the conveying unit 30 includes a plurality of conveying rollers 33 that convey the medium M along a conveying path that passes through the recording position, and a conveying belt 34 that conveys the medium M at the recording position. The conveying belt 34 is wound around a first roller 35 and a second roller 36.

[0044] The conveyor belt 34 is configured to be rotatable with the first roller 35 as a fulcrum. The conveyor belt 34 passes through the support portion moving mechanism 37, thereby Figure 2 The support positions indicated by solid lines and Figure 2 The conveyor belt 34 moves between the avoidance positions indicated by the double-dashed line in FIG. The conveyor belt 34 supports the medium M being conveyed at the supporting position. That is, the conveyor belt 34 has the function of a supporting portion that supports the medium M in a manner that keeps the gap between the medium M being conveyed and the liquid ejection head 22 constant. Here, the conveying direction Y refers to the conveying direction of the medium M at the recording position.

[0045] The medium storage unit 16 is, for example, a box, and is inserted in a detachable manner into a recessed portion (not shown) formed in the housing 18. Figure 2 In the inserted state shown, the medium M stored in the medium storage portion 16 is located in the housing 18. Figure 2 In FIG. 1 , only the uppermost one of the plurality of medium storage sections 16 is shown, and the other medium storage sections 16 are omitted.

[0046] The medium storage section 16 includes a movable edge guide 16A that is operated by a user. The medium M in the medium storage section 16 is positioned in the width direction by the edge guide 16A. The liquid ejection device 11 may also include a device for detecting the size of the medium M stored in the medium storage section 16. Figure 2 The size detection unit 19 is shown.

[0047] The liquid ejection device 11 includes a waste liquid container 50 for storing waste liquid generated during maintenance of the liquid ejection head 22. The waste liquid container 50 is detachably mounted on a holder 51. The waste liquid container 50 mounted on the holder 51 is arranged at a predetermined position in the housing 18.

[0048] The maintenance unit 40 performs maintenance operations such as idle ejection and cleaning in the liquid ejection head 22 in order to prevent or eliminate ejection failures caused by clogging of the nozzles 21 or adhesion of foreign matter.

[0049] The maintenance unit 40 includes a plurality of caps 41 configured to cover a plurality of nozzle groups, a discharge mechanism 44 for discharging liquid in the caps 41, and a cap moving mechanism 45 for moving the caps 41. The discharge mechanism 44 includes a waste liquid flow path 42 connecting the caps 41 and a holder 51, and a decompression unit 43 provided in the middle of the waste liquid flow path 42. The liquid ejection device 11 includes a waste liquid storage body 50 for storing waste liquid discharged from the caps 41 by the discharge mechanism 44.

[0050] The cover moving mechanism 45 moves the cover 41 Figure 2 The avoidance position indicated by the solid line in FIG. 1 and the capping position in contact with the nozzle surface 28 of the liquid ejection head 22 ( Figure 2 In addition, when the cover 41 moves to the capping position, the conveyor belt 34 moves from Figure 2 The support position indicated by the solid line in the figure is avoided to Figure 2 The avoidance position is indicated by the double-dotted line.

[0051] Capping is performed by moving the cap 41 to the capping position and contacting the nozzle surface 28 of the liquid ejection head 22 in a manner surrounding the nozzle 21. When liquid is not ejected, the capping suppresses the thickening of the liquid in the nozzle 21, thereby preventing the occurrence of ejection defects.

[0052] Here, the so-called empty ejection refers to an ejection action for maintenance, in which droplets not related to printing are ejected from the nozzle 21 for the purpose of maintenance of the liquid ejection head 22. Empty ejection is also called flushing. By performing empty ejection, thickened ink, bubbles or foreign matter that cause poor ejection are discharged from the nozzle 21. The liquid discharged as waste liquid by empty ejection is stored in the cap 41. During the flushing period, maintenance period and the end of printing, the cap 41 is arranged in the capping position. During flushing, droplets are ejected from the nozzle 21 toward the cap 41 by the liquid ejection head 22, thereby performing empty ejection.

[0053] In addition, cleaning is performed by driving the decompression unit 43 while the cover 41 is placed in the capping position. The cleaning of this example is suction cleaning in which the liquid is sucked out from the nozzle 21 by setting the substantially closed space between the nozzle surface 28 and the cover 41 to negative pressure. The cover 41 is connected to a waste liquid flow channel 42 at one end on the opposite side of the opening. The waste liquid flow channel 42 is connected to the retaining frame 51 at its other end via the decompression unit 43. The cover 41 is connected to the waste liquid storage body 50 via the waste liquid flow channel 42, the decompression unit 43 and the retaining frame 51.

[0054] 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 storage body 50. In addition, if a predetermined amount of waste liquid discharged from the nozzle 21 by the empty ejection is accumulated in the cap 41, the decompression unit 43 can be driven in a state where the cap 41 is separated from the liquid ejection head 22 by a predetermined gap distance, so that the liquid in the cap 41 is recovered in the waste liquid storage body 50 through the waste liquid flow path 42. This suction is called empty suction. Empty suction is performed to discharge the liquid accumulated in the cap 41.

[0055] like Figure 2 As shown, a liquid supply mechanism 60 is provided between the liquid container 24 and the liquid ejection unit 20, in the middle of the supply flow path 25. The liquid supply mechanism 60 has the function of supplying liquid and pressurizing the liquid so as to bulge the liquid from the nozzle 21 for maintenance.

[0056] Regarding the structure of the liquid supply mechanism 60

[0057] Next, refer to Figure 3 , the liquid supply mechanism 60 will be described. The liquid storage body 24 includes a liquid bag 24A for storing liquid, and a housing 24B for storing the liquid bag 24A. When the liquid storage body 24 is mounted on a holder (not shown), the liquid bag 24A is connected to the supply flow path 25, and the housing 24B is connected to the first air flow path 71. The liquid storage body 24 is pressurized by the space in the housing 24B, so that the liquid is supplied from the liquid bag 24A. When the liquid is ink, the liquid bag 24A is an ink bag.

[0058] The liquid supply mechanism 60 includes a sub-tank 61, a self-sealing valve 62, an opening and closing valve 63, and a head tank 64, which are provided in the middle of the supply flow path 25. The self-sealing valve 62, the opening and closing valve 63, and the head tank 64 are provided for each of the liquid ejection heads 22 constituting the liquid ejection unit 20. The opening and closing valve 63 is, for example, a choke valve used in choke cleaning described later.

[0059] In the supply flow channel 25, a plurality of flow channel valves 65 driven, for example, by a solenoid SL are provided at the portion between the liquid storage body 24 and the sub-tank 61. When printing is performed, the flow channel valve 65 is opened, and liquid from the liquid storage body 24 is supplied to the sub-tank 61. The sub-tank 61 is provided with an end sensor (not shown) for detecting when the amount of the stored liquid falls below a threshold value. When the end sensor detects the end of the liquid, the flow channel valve 65 is closed by the control unit 100. In addition, Figure 2In the example of FIG. 1 , each supply channel 25 connected to the two black liquid storage bodies 24K is connected upstream of the sub-tank 61. A one-way valve 29 is provided in the middle of each supply channel 25 connected to the black liquid storage body 24K, and the one-way valve 29 allows the liquid to be supplied from the liquid storage body 24K toward the sub-tank 61 in the liquid supply direction and prevents the liquid from moving in the direction opposite to the liquid supply direction.

[0060] The liquid supply mechanism 60 includes a pressurizing unit 66 for generating and controlling air pressure when the opening and closing valve 63 and the head tank 64 are driven by air pressure. The pressurizing unit 66 controls the plurality of nozzle groups N1 to N4 (see Figure 4 ) is pressurized. The pressurizing unit 66 pressurizes the liquid in the nozzle 21, thereby causing the liquid to bulge out from the nozzle 21.

[0061] The pressurizing unit 66 includes a liquid chamber 95 provided in the middle of the supply flow path 25 for supplying liquid to the liquid ejection unit 20, an on-off valve 63 provided on the supply flow path 25 at an upstream position relative to the liquid chamber 95, and a driving unit 67 capable of displacing a membrane member 97 constituting a part of a wall portion forming the liquid chamber 95. That is, the pressurizing unit 66 is composed of the on-off valve 63, the head tank 64, the driving unit 67 for generating and controlling air pressure for driving these components, and the like. The liquid chamber 95 is configured so that the 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.

[0062] The driving unit 67 includes a motor 67M, a pressure pump 67P driven by the motor 67M, a pressure sensor 68 for detecting the air pressure pressurized by the pressure pump 67P, a selection valve 69 for selecting a destination for the pressurized air pressure, and a motor 70 connected to the selection valve 69. The selection valve 69 includes a pressure tank 69A (not shown) inside. The pressure sensor 68 detects the air pressure in the pressure tank 69A. The motor 70 is a driving source for the selection valve 69. The control unit 100 controls the rotation position of the motor 70 to select the opening and closing of each valve (e.g., an on-off valve) in the selection valve 69, thereby selecting the destination for the air pressure from the selection valve 69.

[0063] The other end of a first air flow passage 71, one end of which is connected to the liquid storage body 24 in order to pressurize the liquid bag 24A (e.g., ink bag) in the liquid storage body 24, is connected to the selector valve 69. In addition, the other ends of a second air flow passage 72 and a third air flow passage 73, each of which one end is connected to the opening and closing valve 63 of each liquid ejecting head 22 and the air chamber of the head tank 64, are connected to the selector valve 69. In addition, an atmosphere release valve 71A is provided on the first air flow passage 71.

[0064] like Figure 3 As shown, the maintenance unit 40 includes a cap unit 75 having a plurality of the caps 41 described above, and a wiping unit 76 that can wipe the nozzle surface.

[0065] The cover 41 is in the shape of a bottomed box that is open upward, and is configured to be relatively movable with respect to the nozzle surface 28 of the liquid ejection head 22. The cover 41 moves from the avoidance position to a flushing position that moves in a direction close to the liquid ejection head 22 and is separated from the nozzle surface 28 by a gap distance, and a capping position that contacts the nozzle surface 28 to form a substantially closed space between the nozzle surface 28 and the cover 41. The position of the cover 41 when the liquid ejection head 22 performs an empty ejection is the flushing position.

[0066] The wiping portion 76 has a scraper 77 for wiping the nozzle surface 28. The wiping portion 76 is moved to the retracted position (see Figure 2 ) in the avoided state, the wiping portion 76 is moved in the width direction X of the medium M by utilizing the driving force of the motor 78 as the driving source, thereby wiping the nozzle surfaces 28 of the plurality of liquid ejecting heads 22.

[0067] A plurality of covers 41 are connected to the waste liquid storage body 50 through a waste liquid flow channel 42. In the middle of the waste liquid flow channel 42, a decompression tank (not shown) and a plurality of opening and closing valves 81 are provided. The plurality of opening and closing valves 81 are opened and closed by the power of a motor 82 controlled by the control unit 100. When the opening and closing valve 81 is opened, negative pressure is introduced into the cover 41, and when the opening and closing valve 81 is closed, negative pressure is not introduced into the cover 41. By introducing negative pressure into the cover 41 when the cover 41 is in contact with the nozzle surface 28 of the liquid ejection head 22, suction cleaning is performed to forcibly suck and discharge liquid from the nozzle 21. In addition, cleaning can also be pressurized cleaning in which liquid is forcibly discharged from the nozzle 21 by pressurizing the liquid storage body 24.

[0068] The liquid obtained by wiping the nozzle surface 28 is accumulated in the wiping portion 76. The portion of the wiping portion 76 where the liquid is accumulated is connected to the waste liquid storage body 50 through the discharge flow path 83. An on-off valve 84 is provided in the middle of the discharge flow path 83. When the on-off valve 84 is opened by the control of the control unit 100, the waste liquid is recovered from the wiping portion 76 through the discharge flow path 83 to the waste liquid storage body 50.

[0069] Regarding the structure of the nozzle surface of the liquid ejection unit 20

[0070] Next, refer to Figure 4 , the structure of the nozzle surface of the liquid ejection portion 20 is described.

[0071] like Figure 4 As shown in the figure, the liquid ejection unit 20 is configured to perform recording by ejecting liquid from a plurality of nozzle groups N1 to N4 formed on the nozzle surface 28. Specifically, at the bottom of the liquid ejection head 22 provided in the liquid ejection unit 20, a plurality of unit ejection heads 27 are arranged at a fixed interval in the width direction X. The plurality of unit ejection heads 27 are arranged in a posture inclined at a predetermined angle with respect to the conveying direction Y in which the medium M is conveyed.

[0072] For example, for every three unit ejection heads 27, Figure 4 A cover 41 indicated by a double-dotted line is opposite thereto. Figure 4 As shown, the cap 41 has a parallelogram-shaped opening shape when viewed in a plan view (ie, viewed from below), and can cap the unit ejection heads 27 arranged obliquely with respect to the conveying direction Y in groups of three.

[0073] exist Figure 5 , three unit ejection heads 27 are shown as units of the liquid ejection head 22 that are capped by a cap 41. The unit ejection head 27 has a plurality of nozzle groups N1 to N4 (for example, four rows) formed by arranging a plurality of nozzles 21 opening on the nozzle surface 28 in a row. Each nozzle group N1 to N4 is formed in such a way that a predetermined number of nozzles 21 are arranged in a row along the length direction of the unit ejection head 27. Figure 5 In the embodiment of the present invention, the number of nozzles 21 is simplified. However, in reality, among the nozzles 21, a predetermined number (eg, approximately 400) within a range of 200 to 1000 nozzles 21 forms one nozzle group.

[0074] The liquid ejection device 11 of this embodiment can implement color printing. In the example where the liquid is ink, the nozzle 21 includes a nozzle KN that ejects black ink, a nozzle YN that ejects yellow ink, a nozzle MN that ejects magenta ink, and a nozzle CN that ejects cyan ink. The nozzle group N1 is composed of a plurality of nozzles KN arranged in a row with a fixed nozzle pitch. The nozzle group N2 is composed of a plurality of nozzles YN arranged in a row with a fixed nozzle pitch. The nozzle group N3 is composed of a plurality of nozzles MN arranged in a row with a fixed nozzle pitch. The nozzle group N4 is composed of a plurality of nozzles CN arranged in a row with a fixed nozzle pitch.

[0075] For each nozzle KN, YN, MN, CN, the position obtained by projecting in the conveying direction Y is arranged at equal intervals for each color in the entire width direction area of ​​the medium M of the maximum width. In other words, the distance of the equal interval becomes the dot pitch when printing on the medium M. In this way, in the liquid ejection head 22, the unit ejection head 27 is arranged at a predetermined inclination angle so that the projected nozzles when the nozzles 21 are projected in the conveying direction Y are arranged in the width direction at a pitch corresponding to the printing resolution.

[0076] like Figure 5 As shown in the figure, in the liquid ejection section 20, the group of black nozzles KN, i.e., the nozzle group N1, is adjacent to the group of yellow nozzles YN, i.e., the nozzle group N2, and the group of magenta nozzles MN, i.e., the nozzle group N3, is adjacent to the group of cyan nozzles CN, i.e., the nozzle group N4. Therefore, yellow and black are easily mixed, and cyan and magenta are easily mixed. When the mixed ink is ejected from the nozzle 21 where the mixed color occurs, stripes of the mixed colors are easily generated in the printing on the medium M. In particular, when the black ink is mixed in the yellow nozzle YN, dark stripes are generated on the light color printing, and therefore the stripes caused by the mixed color are easily conspicuous.

[0077] like Figure 5 As shown in the figure, the nozzle surface 28 of the liquid ejection part 20 is wiped by the wiping part 76 moving in the width direction X. By this wiping, the openings of the respective nozzles 21 constituting the plurality of nozzle groups N1 to N4 are wiped together with the nozzle surface 28. With respect to the bottom surface of the liquid ejection head 22, the unit ejection heads 27 and the other parts thereof are formed on substantially the same plane, and the bottom surface thereof as a whole becomes the nozzle surface 28 to be wiped by the wiping part 76.

[0078] In this embodiment, when the wiping portion 76 wipes the nozzle surface 28, the pressurizing portion 66 (see Figure 3) so that the liquid in the nozzle 21 is pressurized. In a state where the liquid is bulging out from all the nozzles 21 due to the pressurization, the wiping portion 76 wipes the nozzle surface 28. In addition, the details of the control content during the wiping will be described later.

[0079] Regarding the structure and operation of the pressurizing unit 66

[0080] Next, refer to Figure 6 to Figure 9 , the structure and operation of the pressurizing part 66 are explained. In the middle of the supply channel 25, the aforementioned self-sealing valve 62, the opening and closing valve 63, and the head tank 64 constituting the pressurizing part 66 are sequentially arranged in this order along the liquid supply direction. The self-sealing valve 62 is a component that uses the difference between the pressure of the supply channel 25 and the atmospheric pressure to open the supply channel 25. That is, the self-sealing valve 62 is a structure that opens the supply channel 25 and replenishes ink from the upstream side when the liquid is consumed from the liquid ejection head 22 and the downstream side becomes a negative pressure. The self-sealing valve 62 has a valve body (not shown) that opens and closes the supply channel 25, a force applying component (not shown) that applies force in the direction of blocking the valve body, and a flexible component (not shown) that withstands the atmospheric pressure and pushes the valve body open by overcoming the force of the force applying component when the supply channel 25 becomes a negative pressure.

[0081] The on-off valve 63 is provided on the downstream side of the self-sealing valve 62. The on-off valve 63 includes a liquid chamber 91 forming a part of the supply flow path 25, and an air chamber 92 separated from the liquid chamber 91 via a membrane member 93. The on-off valve 63 is a member that opens and closes the supply flow path 25 by deforming the membrane member 93 using the pressure difference between the liquid chamber 91 and the air chamber 92. The operating pressure of the on-off valve 63 is set to be adjustable by an operating pressure adjustment spring 94.

[0082] The liquid chamber 91 is formed inside the housing of the on-off valve 63, and a part of its wall is formed by the membrane member 93. The inlet of the liquid chamber 91 is formed on 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. Thus, the on-off valve 63 can block the supply flow path 25.

[0083] The air chamber 92 is located in the internal space of the housing of the on-off valve 63, at a position separated from the liquid chamber 91 by a membrane member 93. The membrane member 93 is formed, for example, of a flexible resin film (e.g., an elastomer). The membrane member 93 is fixedly mounted on the inner wall surface of the on-off valve 63 in a predetermined loose state in a manner covering the inlet and outlet of the liquid chamber 91. The working pressure regulating spring 94 is a member for regulating the working pressure of the on-off valve 63, and is disposed in the liquid chamber 91, and applies force to the membrane member 93 toward the air chamber 92 side.

[0084] The header tank 64 is provided on the downstream side of the on-off valve 63. The header tank 64 is a member that 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 that changes the spatial volume of the liquid chamber 95 by deforming the membrane member 97 due to the pressure difference between the liquid chamber 95 and the air chamber 96. The operating pressure of the header tank 64 is set to be adjustable by an operating pressure adjustment spring 98.

[0085] The liquid chamber 95 is formed inside the head tank 64, and a part of its wall surface is formed by the 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 will not be blocked. The air chamber 96 is located in the internal space of the head tank 64, at a position on the opposite side of the liquid chamber 95 across the membrane member 97.

[0086] The membrane member 97 is formed of, for example, a flexible resin film (e.g., an elastomer). The membrane member 97 is fixedly mounted on the inner wall surface of the head tank 64 in a predetermined loose state in a manner covering the inlet and outlet of the liquid chamber 95. The working pressure regulating spring 98 is a member for regulating the working pressure of the head tank 64, and is disposed at the liquid chamber 95 to apply force to the membrane member 97 toward the air chamber 96 side.

[0087] The supply flow path 25 communicating with the outlet of the liquid chamber 95 of the head tank 64 is connected to the liquid ejection head 22 .

[0088] For example, when cleaning is performed, the cap 41 is in a capping state in which the cap 41 contacts the nozzle surface 28. When the nozzle surface 28 is wiped by the wiping portion 76, a small amount of liquid is discharged from the nozzle 21 in advance compared to cleaning. After the discharge, the nozzle surface 28 is wiped by the wiping portion 76 in a state where the liquid bulges out from the nozzle 21. Alternatively, the liquid may be bulged out from the nozzle 21 without being discharged from the nozzle 21.

[0089] The cleaning includes a first cleaning (wiping cleaning) performed before wiping, and a second cleaning performed by the maintenance unit 40. As the first cleaning, there is wiping cleaning in which a small amount of ink is replaced to restore the ejection characteristics of the liquid ejection head 22. In addition, as the second cleaning, there is a normal cleaning in which the ink is replaced with the opening and closing valve 63 open and not moving, and a choke cleaning in which the ink is replaced by opening and closing the opening and closing valve 63.

[0090] About First Cleaning

[0091] Next, refer to Figure 6 to Figure 15 In the wiping cleaning, by switching the selector valve 69, the first cleaning is described. Figure 6As shown in the figure, air is introduced into the air chamber 92 of the on-off valve 63. Figure 6 The open position indicated by the two-dot chain line in the figure is bent toward the closed position indicated by the solid line, so that the on-off valve 63 is closed.

[0092] Next, by switching the selector valve 69, Figure 7 As shown in the figure, when the on-off valve 63 is closed, air is introduced into the air chamber 96 of the head tank 64. Figure 7 The non-pressurized position indicated by the two-dot chain line in the figure is bent toward the pressurized position indicated by the solid line, so that the liquid in the liquid chamber 95 is pressurized. In this way, the first cleaning is performed.

[0093] Refer to the cross section of the nozzle. Figure 10 to Figure 12 The first cleaning is described below. Fig.10 As shown in the figure, the liquid IL in the nozzle 21 of the liquid ejection head 22 forms a concave meniscus MS which is recessed from the opening of the nozzle 21 to the inside relative to the nozzle surface 28. From this state, the liquid IL in the head tank 64 is discharged through the membrane member 97 to the head tank 64. Figure 7 The pressurized position shown in the figure is operated so that the (pressurized) liquid pushed out from the liquid chamber 95 is discharged from the nozzle 21 in a small amount corresponding to the volume of the liquid chamber 95. As a result, Fig.11 As shown, the liquid IL bulges out from the nozzle 21. The process of forming the bulged portion EL may be accompanied by the discharge of the liquid IL from the nozzle 21, or the pressurized liquid may be allowed to stay in a state of bulging out from the opening of the nozzle 21 without being discharged.

[0094] like Fig.11 As shown in FIG. 1 , when the liquid is bulging out from the nozzle 21, the nozzle surface 28 is wiped by the wiping portion 76. Fig.10 When wiping is performed with the concave meniscus MS shown, a film of the wiped liquid IL is formed outside the concave portion of the meniscus MS, and air is trapped between the film and the meniscus MS. This air may become bubbles and adversely affect the ejection performance of the liquid during subsequent printing.

[0095] In contrast, Fig.11 As shown in the figure, when the bulging portion EL from which the liquid IL bulges out from the nozzle 21 is wiped by the wiping portion 76, since it is possible to avoid the situation where air is sealed in the liquid IL in the nozzle 21, it is possible to prevent the mixing of bubbles in the nozzle 21. In addition, by discharging a small amount of liquid I, the thickened liquid IL or bubbles in the nozzle 21 are discharged from the nozzle 21.

[0096] like Figure 8As shown, when the air chamber 92 passing through the on-off valve 63 is decompressed to atmospheric pressure and the film member 93 is bent toward the bulging side, the on-off valve 63 is opened.

[0097] Next, if Fig. 9 As shown in FIG. 1 , the air chamber 96 of the head tank 64 is depressurized to atmospheric pressure, so that the membrane member 97 of the head tank 64 is displaced from the pressurized position to the non-pressurized position. As a result, a force acts to suck liquid from the nozzle 21 side into the liquid chamber 95. Fig.13 As shown in FIG. 2 , the liquid IL in the nozzle 21 is sucked in the depth direction. As a result, a meniscus MS of the liquid IL is formed in the opening of the nozzle 21 .

[0098] For example, Fig.14 As shown in FIG. 1 , when the wiping portion 76 wipes the nozzle surface 28, the liquid IL accumulated along the ridge of the scraper 77 may remain on the nozzle surface 28 for some reason. The attached liquid WL remaining on the nozzle surface 28 is a mixed color liquid. Fig.14 As shown in FIG. 1 , there is a case where the remaining attached liquid WL contacts the nozzle 21. In this case, there is a case where the head tank 64 is sucked when it moves from the pressurized position to the non-pressurized position. Fig.15 As shown, the mixed color attached liquid WL is sucked into the nozzle 21 .

[0099] In this embodiment, Fig.14 The mixed color attached liquid WL that contacts the nozzle 21 shown in FIG. 1 is detected. Then, after the detection, the nozzle 21 (see FIG. 1 ) that has the possibility that the mixed color liquid IL will be sucked is selected. Fig.15 ) is specially designated. From the specially designated nozzle 21, an empty ejection is performed with an empty ejection amount that is larger than the usual empty ejection amount. For example, if an empty ejection is performed with an amount that can discharge the sucked mixed color attached liquid WL in both the nozzle 21 that sucked the mixed color attached liquid WL and the nozzle 21 that did not suck, excess liquid will be discharged in vain from the nozzle 21 that did not suck the mixed color attached liquid WL. Therefore, in the present embodiment, the nozzle 21 that sucked the mixed color attached liquid WL is detected, and a first ejection amount of liquid IL that can discharge the mixed color attached liquid WL is performed from the nozzle 21 for a specific nozzle 21 that is specially designated based on the detection result. Fig.15 The first empty ejection is indicated by a large hollow arrow mark in FIG. 1. Then, the liquid IL is ejected at a second ejection amount smaller than the first ejection amount for normal nozzles 21 other than the specific nozzles 21. Fig.15 The second air jet is indicated by a smaller hollow arrow mark.

[0100] Regarding the structure of the driving system of the liquid ejection head 22

[0101] Next, refer to Fig.16 , the detailed structure of the local area including the driving system of the liquid ejecting head 22 for ejecting liquid will be described.

[0102] The liquid ejection head 22 includes an ejection portion D provided for each nozzle 21 . Fig.16 The ejection unit D shown in the figure includes a nozzle 21, an actuator 200, a cavity 264 (pressure chamber), and a vibration plate 265. The nozzle 21 is connected to the cavity 264. The ejection unit D ejects the liquid (e.g., ink) in the cavity 264 from the nozzle 21 by vibrating the vibration plate 265 through the drive of the actuator 200. Fig.16 In FIG. 1 , one of the ejection portions D, which is the same number as the plurality of nozzles 21, is shown.

[0103] The liquid ejection unit 20 has the same number of nozzles 21. Fig.16 The liquid ejection unit 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 vibration plates 265. The plurality of actuators 200 are driven by a head drive circuit 110 (see FIG. 1 ) as an example of a drive circuit. Fig.18 ) to be driven individually, thereby partially displacing the plurality of vibration plates 265. The displaced vibration plates 265 cause liquid to be ejected from the nozzles 21 corresponding to the driven actuators 200.

[0104] The cavity 264 is a space defined by a cavity plate 266 having a concave portion and formed into a predetermined shape, a nozzle plate 267 formed with the nozzle 21, and a vibration plate 265. The cavity 264 is connected to a liquid reservoir 272 through a liquid supply port 271. The liquid reservoir 272 is connected to a liquid storage body 24 through a liquid supply channel 273.

[0105] The actuator 200 may also be, for example, Fig.16 The piezoelectric element of the single piezoelectric (single crystal) type as shown in FIG. In this case, the piezoelectric element constituting the actuator 200 has a lower electrode 201, an upper electrode 202, and a piezoelectric body 203 disposed between the lower electrode 201 and the upper electrode 202. Furthermore, 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. Based on the applied voltage, the actuator 200 is Figure 3In this example, the lower electrode 201 is a common electrode common to the plurality of actuators 200 , and the upper electrode 202 is an independent electrode that supplies the drive signal Vin to the plurality of actuators 200 individually.

[0106] The lower electrode 201 of the actuator 200 is bonded to the vibration plate 265 which is set to block the upper surface opening of the cavity plate 266. Therefore, when the actuator 200 vibrates by the drive signal Vi, the vibration plate 265 also vibrates. Then, the volume of the cavity 264 changes by utilizing the vibration of the vibration plate 265, and the pressure of the liquid in the cavity 264 changes accordingly, so that a part of the liquid filled in the cavity 264 is ejected from the nozzle 21.

[0107] The amount of liquid in the cavity 264 that is reduced by the ejection of the liquid is replenished by supplying the liquid from the liquid reservoir 272 to the cavity 264. In addition, the liquid is supplied from the liquid storage body 24 to the liquid reservoir 272 through the liquid supply flow path 273. The liquid supply flow path 273 is connected to the liquid storage body 24. Figure 2 The supply flow channel 25 is shown to be connected.

[0108] Although a piezoelectric element is used as the actuator 200 in this embodiment, the actuator 200 is not limited to a piezoelectric element. For example, the actuator 200 may be an electrostatic element or a heater element that boils a liquid such as ink by heating and ejects the liquid from the nozzle 21 using the force of bubbles.

[0109] Electrical structure of liquid ejection device 11

[0110] Next, refer to Fig.17 , the electrical structure of the liquid ejection device 11 is described. Fig.17 As shown, the control unit 100 is electrically connected to the operation unit 15, the liquid ejection unit 20, the conveying unit 30, the maintenance unit 40, the pressurizing unit 66, the wiping unit 76, etc. 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 printing control unit 102 and a nozzle inspection unit 103. The printing 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. In the storage unit 105, Fig.28 The control unit 100 executes the maintenance control routine and other programs through the computer 101.

[0111] The control unit 100 is not limited to a component that implements software processing for all the processes performed by itself. For example, the control unit 100 may also have a dedicated hardware circuit (such as an integrated circuit for a specific purpose: ASIC) that implements hardware processing for at least a part of the processes performed by itself. That is, the control unit 100 can be configured as a circuit (circuitry) including one or more processors that act according to a computer program (software), one or more dedicated hardware circuits that perform at least a part of various processes, or a combination thereof. The processor includes a CPU and a memory such as RAM and ROM, and the memory stores program codes or instructions that are configured to enable the CPU to perform processing. The memory, that is, a computer-readable medium, includes all available media that can be accessed by a general-purpose or special-purpose computer. The control unit 100 may also be configured at least in part by hardware. That is, the control unit 100 may also be implemented by the collaborative work of software and hardware, or by hardware.

[0112] The printing control unit 102 manages various controls such as printing control, maintenance control, and wiping control. Fig.18 The head driving circuit 110 shown as an example of a driving circuit in the liquid ejection head 22 outputs a control signal to control the plurality of ejection portions D.

[0113] The nozzle inspection unit 103 performs a nozzle inspection to check whether the nozzles 21 of the liquid ejection head 22 have an ejection abnormality. The nozzle inspection unit 103 detects a nozzle with an ejection abnormality through the nozzle inspection. The nozzle inspection unit 103 of this example is based on the ejection abnormality detection unit 112 (see Fig.17 ) is used as the basis for checking the ejection abnormality of the nozzle 21.

[0114] Electrical structure involved in discharge control and discharge abnormality detection

[0115] Next, refer to Fig.18 , the electrical structure involved in the control of the liquid ejection head 22 and the ejection abnormality detection implemented by the control unit 100 is described. Fig.18 As shown, the control unit 100 is electrically connected to the liquid ejection head 22 via a wiring cable (not shown) in a state where various signals Sw, SI, COM, and Ds can be transmitted and received.

[0116] The liquid ejection head 22 includes a head driving circuit 110 and an ejection unit 130. The head driving circuit 110 includes a driving signal generating unit 111 that generates a driving signal Vin based on the signals SI and COM input from the printing control unit 102, and an ejection abnormality detecting unit 112 that detects an ejection abnormality (abnormal nozzle) of the nozzle 21 based on the residual vibration signal Vout from the ejection unit D. In addition, in the present embodiment, the ejection abnormality detecting unit 112 and the nozzle inspection unit 103 constitute a detection unit 106. The detection unit 106 detects the nozzle 21 that is in contact with the attached liquid WL attached to the nozzle surface 28 based on the residual vibration of the displaced vibration plate 265.

[0117] In addition, the head driving circuit 110 includes a switching unit 113 that switches the connection destination to the ejection unit D between the driving signal generating unit 111 and the ejection abnormality detecting unit 112. The switching unit 113 switches between a first connection state in which the ejection unit D is electrically connected to the driving signal generating unit 111 and a second connection state in which the ejection unit D is electrically connected to the ejection abnormality detecting unit 112 based on a switching signal Sw from the nozzle inspection unit 103. That is, the switching unit 113 switches between the output of the driving signal Vin from the driving signal generating unit 111 to the ejection unit D and the input of the residual vibration signal Vout from the ejection unit D to the ejection abnormality detecting unit 112.

[0118] When the actuator 200 (see Fig.16 ) and the drive signal Vin is supplied from the head drive circuit 110, after the vibration plate 265 of the ejection part D is bent upward by the electrostrictive action of the piezoelectric element constituting the actuator 200, it is restored by its elastic restoring force. Fig.16 ) in the cavity 264, thereby causing droplets to be ejected from the nozzle 21 connected to the cavity 264.

[0119] The drive signal generating unit 111 generates a drive signal Vin for driving each of the plurality of ejection units D provided in the ejection unit 130 based on the control signals such as the bus data SI and the drive waveform signal COM supplied from the printing control unit 102. Each ejection unit D is driven based on the supplied drive signal Vin, and ejects the liquid filled therein from the nozzle 21 to the medium M. In addition, the drive signal generating unit 111 can generate the drive signal Vin including a voltage waveform that can vibrate the vibration plate 265 with an amplitude that ejects the liquid from the nozzle 21, and a drive signal Vin including a voltage waveform that can micro-vibrate the vibration plate 265 with an amplitude that is small enough not to eject the liquid from the nozzle 21. Although the nozzle inspection performed by the detection unit 106 is performed in a manner that micro-vibrates the vibration plate 265, it may also be performed in a manner that ejects droplets from the nozzle 21.

[0120] The discharge abnormality detection unit 112 inputs a residual vibration signal Vout, which is a residual vibration signal Vout generated after the discharge unit D is driven by the driving signal Vin and passes through the vibration plate 265 (see Fig.16 ) and receives the residual vibration of the liquid in the cavity 264 of the ejection portion D. The ejection abnormality detection unit 112 detects whether the nozzle 21 to be inspected is a normal nozzle capable of ejecting droplets normally or an abnormal nozzle that cannot eject droplets normally based on the input residual vibration signal Vout, and outputs the detection result as a detection signal Ds to the control unit 100. When the detection result is an abnormal nozzle, the ejection abnormality detection unit 112 outputs the detection signal Ds according to multiple reasons (bubble mixing, drying, paper dust adhesion) together with the nozzle position information that can specifically specify the position of the abnormal nozzle.

[0121] In the ejection abnormality inspection, the vibration caused by the excitation remains in the vibration plate 265 of each ejection portion D during the period from the ejection action of one ink droplet or the completion of one excitation action for micro-vibrating the ink in the nozzle 21 until the start of the next excitation action. The residual vibration generated in the vibration plate 265 of the ejection portion D can be assumed to be a vibration having a natural vibration frequency determined by the acoustic resistance Res generated by the shape of the nozzle 21 or the liquid supply port 271 or the viscosity of the ink, the inertial resistance Int generated by the weight of the ink in the flow path, and the compliance Cm of the vibration plate 265, etc.

[0122] Fig.19FIG. 2 shows an equivalent circuit representing a calculation model of a single vibration assuming the residual vibration of the vibration plate 265 based on the above assumption. The calculation model of the residual vibration of the vibration plate 265 is expressed by the sound pressure Ps, the inertial resistance Int, the compliance Cm, and the acoustic resistance Res. Furthermore, the volume velocity Uv can be calculated. Fig.19 The circuit gives a step response at sound pressure Ps.

[0123] Fig. 20 : is a graph showing the waveform of the residual vibration signal Vout. Fig. 20 As shown in FIG. 1 , when the ejection unit D ejects droplets normally, the residual vibration signal Vout becomes a predetermined waveform in normal state (see FIG. 1 ). Fig. 20 However, in the case of abnormal ejection of droplets, the waveform of the residual vibration signal Vout becomes different from that in the normal state. Fig. 20 As shown, when bubbles are mixed into the liquid in the nozzle 21 or the cavity 264, the residual vibration signal Vout becomes the residual vibration waveform L1 when the bubbles are mixed. In addition, when the liquid in the nozzle 21 thickens or solidifies due to drying, the residual vibration signal Vout becomes the residual vibration waveform L2 when it is dry. Furthermore, when paper dust is attached to the opening of the nozzle 21, the residual vibration signal Vout becomes the residual vibration waveform L3 when paper dust is attached with a longer period than during normal ejection. According to the above situation, the abnormal ejection of droplets from the liquid ejection head 22 can be detected according to the cause through the difference in residual vibration.

[0124] In addition, if Fig.14 As shown in FIG. 1 , 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, thereby increasing the inertial resistance Int. Therefore, the waveform of the residual vibration signal Vout becomes different between the nozzle 21 in contact with the mixed color liquid WL adhered to the nozzle face 28 and the nozzle 21 in contact with the mixed color liquid WL. In addition, the so-called mixed color liquid WL in contact with the nozzle 21 also includes the case where the mixed color liquid WL is in contact with the opening of the nozzle 21.

[0125] Method for detecting the liquid adhesion state on the nozzle surface 28

[0126] Next, refer to Fig.21 Hereinafter, a detection example in which the nozzle inspection unit 103 inspects the ejection failure of the nozzle 21 and detects the liquid adhesion state on the nozzle surface 28 will be described. Fig.21The graph shown shows an example of detecting the nozzle 21 in contact with the liquid attached to the nozzle surface 28. The horizontal axis of the graph shows the positions of n nozzles 21 arranged in the width direction X. In the graph, n is an example of approximately 240. The vertical axis shows the amplitude (V) of the residual vibration signal Vout. The amplitude is expressed in voltage. Fig.21 In the graph of FIG. 1 , the lower limit value V1 and the upper limit value V2 indicated by the single-dot chain line indicate the liquid not attached to the nozzle surface 28, that is, the attached liquid WL (refer to FIG. 1 ). Fig.14 , Fig.15 ) The amplitude of the normal nozzle 21 that comes into contact with the attached liquid WL is within the lower limit and upper limit of the normal range. The amplitude of the abnormal nozzle that comes into contact with the attached liquid WL is out of the normal range. Fig.21 As shown, for the nozzle 21 in contact with the attached liquid WL, the amplitude deviates from the normal range to the larger side. Therefore, it is possible to detect whether it is an abnormal nozzle 21 in contact with the attached liquid WL or a normal nozzle 21 not in contact with the attached liquid WL based on the amplitude of the residual vibration signal Vout by using the nozzle inspection mechanism.

[0127] exist Fig.21 In the graph of , dark dots represent detection examples when no liquid is attached to the nozzle surface 28, and white dots represent detection examples when liquid is attached to the nozzle surface 28. Fig.21 In the example shown, the abnormal nozzles 21 that are in contact with the attached liquid WL form a group, and the group of these abnormal nozzles is referred to as a contact nozzle group NG1. Fig.21 In the example, the contact nozzle group NG1 appears at two locations. In this embodiment, these contact nozzle groups NG1 are also referred to as "first nozzle groups NG1". And, for normal nozzles 21 other than the first nozzle group NG1, the amplitude takes a value within the normal range. However, in Fig.21 A nozzle nf represented by a white dot having an amplitude within the normal range within the range where the contact nozzle group NG1 exists is presumed to be misdetected. Therefore, if such misdetection is taken into consideration, it is sometimes appropriate to also regard the nozzles adjacent to the abnormal nozzle belonging to the first nozzle group NG1 as abnormal nozzles.

[0128] Furthermore, when the pressure is released from the nozzle 21 in contact with the attached liquid WL, the mixed color attached liquid WL is sucked into the nozzle 21 (see Fig.14 , Fig.15). Therefore, in order to discharge the mixed color liquid WL sucked by the nozzle 21 from the nozzle 21, an empty ejection of liquid not related to printing is performed from the nozzle 21. As for the amount of the mixed color liquid WL sucked by the nozzle 21, since it is generated based on the situation that the head tank 64 moves from the pressurized position to the non-pressurized position, it becomes an amount corresponding to the capacity of the liquid chamber 95. Therefore, in order to discharge the mixed color liquid WL sucked by the nozzle 21 through empty ejection, the liquid is ejected with an empty ejection amount that is larger than the usual empty ejection. In the present embodiment, the empty ejection for discharging the mixed color liquid with a larger empty ejection amount than the usual empty ejection is also referred to as the first empty ejection. In contrast, the empty ejection performed from the nozzle 21 other than the nozzle corresponding to the mixed color liquid is also referred to as the second empty ejection.

[0129] Method for specifying the first nozzle

[0130] Next, refer to Figure 22 to Figure 27 Three embodiments are described below with respect to a method for determining the nozzle 21 to be used as the first empty ejection target after wiping the nozzle surface 28. Figure 22 to Figure 27 In the embodiment, according to the contact with the attached liquid WL, the nozzle 21 whose amplitude is out of the normal range in the nozzle check performed by the detection unit 106 is set as an "abnormal nozzle 21N", and the nozzles other than the above whose amplitude is within the normal range are set as "normal nozzles 21G". In addition, the nozzle 21 for the first empty ejection for discharging the mixed color liquid is set as the first nozzle FN1, and the normal nozzles 21G other than the first nozzle FN1 are set as the second nozzle FN2. In addition, the nozzle 21 set as the first empty ejection target for preventing color mixing, that is, the first nozzle FN1, is also a color mixing prevention corresponding nozzle.

[0131] First embodiment

[0132] right Fig. 22 , Fig.23 1. The first embodiment shown in FIG. 1 is described. In the first embodiment, only the first nozzle group NG1 in contact with the attached liquid WL is set as the object of the first empty ejection. The empty ejection amount ejected from the nozzle 21 detected by the detection unit 106, that is, the first ejection amount, is set to be larger than the empty ejection amount ejected from the other nozzles, that is, the second ejection amount. In addition, the "empty ejection amount ejected from the other nozzles" may also include an ejection amount of 0. In other words, the second empty ejection amount may also be 0.

[0133] Second embodiment

[0134] right Fig.24 , Fig.25In the second embodiment, not only the abnormal nozzle 21N constituting the first nozzle group NG1 in contact with the attached liquid WL but also a number of normal nozzles 21G located consecutively adjacent to the abnormal nozzle 21N are set as the first nozzle FN1 to be the target of the first idle ejection.

[0135] In this case, as the number A of abnormal nozzles 21N in contact with one attached liquid WL increases, the number of normal nozzles 21G that are consecutively adjacent to the abnormal nozzle 21N and are to be the target of the first empty ejection increases by a predetermined number a. Fig.24 In the case where the number of abnormal nozzles 21N in contact with the attached liquid WL is two, the number of normal nozzles 21G that are consecutively adjacent to the abnormal nozzle 21N and should be the target of the first empty ejection, i.e., the predetermined number a, is one, and a total of four nozzles constitute the first nozzle FN1. Fig.25 In the example of the cross-sectional observation of the liquid ejection head 22 shown, the number of abnormal nozzles 21N contacting the large attached liquid WL is six. When the number of abnormal nozzles 21N contacting the attached liquid WL is six, the number of normal nozzles 21G that are consecutively adjacent to the abnormal nozzle 21N and should be the target of the first empty ejection, that is, the predetermined number a, is three, and a total of twelve nozzles constitute the first nozzles FN1.

[0136] That is, as the number A of the abnormal nozzles 21N in contact with the attached liquid WL increases, the number of normal nozzles 21G that are consecutively adjacent to the abnormal nozzle 21N and that should be set as the target of the first empty ejection, i.e., the predetermined number a, increases. In other words, when the number of the abnormal nozzles 21N in contact with the attached liquid WL is B which is greater than A (B>A), the predetermined number a2 of the normal nozzles 21G that are consecutively adjacent to the abnormal nozzle 21N and that should be set as the target of the first empty ejection is set to a value greater than the predetermined number a1 when it is A (a2>a1).

[0137] Third embodiment

[0138] Next, Fig.26 , Fig. 27 The third embodiment shown in FIG. 2 is described. In the third embodiment, when a plurality of attached liquids WL are in contact with the nozzle surface 28, a normal nozzle 21G located between the plurality of attached liquids WL is specifically designated 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 attached liquids WL is less than the predetermined number K, F1 normal nozzles 21G located continuously at adjacent positions from the abnormal nozzle 21N are specifically designated as the first nozzle FN1. F1 is set to be f1 more than the predetermined number a in the second embodiment (F1=a+f1). Fig.26 is an example where f1 is one. In this case, even if there is Fig.21 The nozzle nf that is misdetected as shown can also be specifically designated as the first nozzle FN1 to be the target of the first empty ejection. In this regard, the specified number K can be, for example, one or two. In addition, the specified number K is not limited to one or two, and for example, an appropriate value within the range of K = 3 to 10 can be set, or a value exceeding 10 can be set.

[0139] Fig. 27 2 shows an example in which the number of normal nozzles 21G located between two attached liquids WL exceeds the prescribed number K. In this case, Fig. 27 As shown in the figure, the method of the second embodiment is applied to the normal nozzle 21G located between the plurality of contact nozzle groups NG1 that are in contact with the plurality of attached liquids WL, and is specifically designated as the first nozzle FN1. That is, according to the number of each abnormal nozzle 21N belonging to the plurality of contact nozzle groups NG1 that are in contact with the plurality of attached liquids WL, a predetermined number a of normal nozzles 21G that are continuously adjacent to the abnormal nozzle 21N are specifically designated as the first nozzle FN1.

[0140] The role of implementation

[0141] Next, the operation of the liquid ejection device 11 in this embodiment will be described.

[0142] The following will follow Fig.28 The control unit 100 executes the following operation when the power of the liquid ejection device 11 is turned on. Fig.28 By executing this routine, the first cleaning and wiping are performed when the wiping condition is satisfied.

[0143] First, in step S11, the control unit 100 determines whether it is the wiping time. If it is the wiping time, the process proceeds to step S12, and if it is not the wiping time, the process waits.

[0144] In step S12, the control unit 100 pressurizes the nozzle. Specifically, the control unit 100 controls the selection valve 69 by controlling the motor 70, thereby closing the on-off valve 63, and pressurizing the head tank 64 when the on-off valve 63 is closed. As a result, the membrane part 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 squeezed out 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 squeezed out from the nozzle 21. By pressurizing the liquid, Fig.11As shown in FIG. 2 , the liquid IL bulges out from the nozzle 21. That is, a bulging portion EL is generated in which the liquid IL bulges out from the nozzle 21 in the ejection direction relative to the nozzle surface 28. At this time, the bulging portion EL may be a portion generated as a result of a small amount of liquid IL being discharged from the nozzle 21, or may be a portion in which the liquid IL bulges out from the nozzle 21 without the discharge of the liquid IL from the nozzle 21.

[0145] In step S13, the control unit 100 performs wiping. Specifically, the control unit 100 controls the motor 78 to move the wiping unit 76 along the wiping path in the width direction X. Thus, the wiping unit 76 wipes the nozzle surface 28 through the scraper 77. As a result, Fig.12 , Fig.14 As shown in FIG. 2 , the nozzle surface 28 is wiped by the wiping portion 76, thereby removing the bulging portion EL bulging from the nozzle 21. Fig.12 , Fig.14 As shown, the liquid in the nozzle 21 is planarized so that the portion exposed at the opening thereof is substantially flush with the nozzle surface 28 .

[0146] After being wiped by the wiping portion 76, Fig.14 As shown, a part of the mixed color liquid wiped by the wiping portion 76 may remain on the nozzle surface 28. For example, due to wear (e.g., uneven wear), damage, offset contact, vibration, etc. of the scraper 77 of the wiping portion 76, a part of the wiped liquid may still adhere to the nozzle surface 28 and remain.

[0147] In step S14, the control unit 100 performs a nozzle check. The nozzle check is performed with the head tank 64 in the pressurized position. That is, after pressurization, before the film member 97 of the head tank 64 is returned from the pressurized position to the non-pressurized position, the nozzle check is performed with the film member 97 in the pressurized position. This is because, as Fig.14 As shown in the figure, after the mixed color attached liquid WL is sucked into the nozzle 21, it is impossible to detect that the mixed color attached liquid WL exists on the nozzle surface 28, so the nozzle check is performed in a state where the mixed color attached liquid WL is on the nozzle surface 28. In this embodiment, the attached liquid WL attached to the nozzle surface 28 is detected by the nozzle check.

[0148] The nozzle check is implemented as follows. A driving signal is applied to the actuator 200, so that the vibration plate 265 is vibrated. Next, the control unit 100 switches the switching unit 113. The residual vibration signal Vout is input to the ejection abnormality detection unit 112. Based on the residual vibration signal Vout, the nozzle 21 (abnormal nozzle 21N) that the mixed color liquid WL contacts is detected. At this time, since the thickened liquid or bubbles, paper powder, etc. in the nozzle 21 have been removed from the nozzle 21 by the first cleaning, the nozzle 21 that the mixed color liquid contacts can be detected with less false detection than the case before the first cleaning. In addition, the processing of step S13 and step S14 is equivalent to "wiping the nozzle surface 28 by the wiping unit 76 and detecting by the detection unit 106 while maintaining the action of the pressurization of the pressurization unit 66".

[0149] In step S15, the control unit 100 releases the pressurization of the nozzle 21. As a result, Fig.13 , Fig.15 As shown in FIG. 1 , the attached liquid WL is sucked into the inner side of the nozzle 21. Fig.15 As shown, the mixed color attachment liquid WL that has come into contact with the nozzle 21 is sucked into the inner side of the nozzle 21 by a predetermined amount corresponding to the volume of the liquid chamber 95 .

[0150] The release of the pressurization may be performed at any timing during the period until the idle ejection is performed after the nozzle inspection. The processing of step S15 corresponds to the "action of releasing the pressurization of the pressurizing unit 66".

[0151] In step S16, the control unit 100 determines whether a contact nozzle group exists. The control unit 100 determines whether a contact nozzle group exists based on the detection result of the detection unit 106. If a contact nozzle group exists, the process proceeds to step S17. If no contact nozzle group exists, the process proceeds to step S19. The control unit 100 determines whether a contact nozzle group exists based on the detection result of the detection unit 106. Fig.21 As shown in the figure, the nozzle 21 whose amplitude of the residual vibration signal Vout is within the normal range is determined as the normal nozzle 21G, and the nozzle 21 whose amplitude of the residual vibration signal Vout is out of the normal range is determined as the abnormal nozzle 21N. The group of abnormal nozzles 21N is the contact nozzle group NG1 that contacts the attached liquid WL. In addition, in the present embodiment, the contact nozzle group NG1 includes the case where there is only one abnormal nozzle 21N.

[0152] In step S17, the control unit 100 specifies the color mixing prevention corresponding nozzle corresponding to the contact nozzle group. Using any one of the methods in the first to third embodiments, the color mixing prevention corresponding nozzle is specified based on the abnormal nozzle 21N constituting the contact nozzle group NG1 detected by the detection unit 106. The color mixing prevention corresponding nozzle refers to the first nozzle FN1, which is a nozzle set as the object of the first empty ejection and ejects liquid at the first empty ejection amount. By specifying the color mixing prevention corresponding nozzle, the color mixing prevention corresponding nozzle set with the first empty ejection amount and the other normal nozzles 21G set with the second empty ejection amount are set for all the nozzles 21. In other words, the first empty ejection amount or the second empty ejection amount is set for all the nozzles 21.

[0153] exist Fig. 22 , Fig.23 In the first embodiment shown, only the abnormal nozzle 21N constituting the contact nozzle group NG1 is set as the first nozzle FN1 to be the target of the first empty ejection. That is, the abnormal nozzle 21N is specifically designated as the first nozzle FN1 to be the target of the first empty ejection to eject the liquid at the first empty ejection amount, and the normal nozzle 21G is specifically designated as the second nozzle FN2 to be the target of the second empty ejection to eject the liquid at the second empty ejection amount. In addition, the processing of step S17 set by the method of the first embodiment is equivalent to "setting the empty ejection amount, i.e., the first ejection amount, ejected from the nozzle detected by the detection unit, to be larger than the empty ejection amount, i.e., the second ejection amount, ejected from the other nozzles".

[0154] exist Fig.24 , Fig.25In the second embodiment shown, the abnormal nozzle 21N and the predetermined number a of normal nozzles 21G continuously adjacent to the abnormal nozzle 21N are set as the first nozzle FN1 to be the object of the first empty ejection. In this way, by specifying the color mixing prevention corresponding nozzle, the color mixing prevention corresponding nozzle (first nozzle FN1) to which the first empty ejection amount is set and the normal nozzles 21G (second nozzle FN2) other than the abnormal nozzle 21 to which the second empty ejection amount is set are set for all the nozzles 21. In other words, the first empty ejection amount or the second empty ejection amount is set for all the nozzles 21. In addition, the processing of step S17 set by the method of the second embodiment is equivalent to "setting the empty ejection amount, i.e., the first ejection amount, ejected from the nozzle detected by the detection unit 106 and the predetermined number a of nozzles continuously adjacent to the abnormal nozzle, i.e., the first ejection amount, to be greater than the empty ejection amount, i.e., the second ejection amount, ejected from the other nozzles". Furthermore, the processing of step S17 set by the method of the second embodiment is equivalent to "for the predetermined number a, the number A of consecutively adjacent nozzles detected by the detection unit 106 is set to be larger". Here, the "number A of consecutively adjacent nozzles" may also include misdetected nozzles nf that are missed due to non-detection of only one nozzle 21 in the contact nozzle group NG1 detected by the detection unit 106.

[0155] exist Fig.26 , Fig. 27 In the third embodiment shown, when the number of normal nozzles 21G located between the plurality of contact nozzle groups NG1 contacting the plurality of attached liquids WL is less than the prescribed number K, F1 normal nozzles 21G located consecutively adjacent to the abnormal nozzle 21N are specifically designated as the first nozzle FN1. F1 is set to be f1 more than the predetermined number a in the second embodiment (F1=a+f1). In addition, the processing of step S17 set by the method of the third embodiment is equivalent to "when a plurality of contact nozzle groups are detected by the detection unit, if the number of nozzles located between the plurality of contact nozzle groups is less than the prescribed number, the empty ejection amount ejected from the nozzles located between the plurality of contact nozzle groups is set to be greater than the empty ejection amount ejected from each nozzle other than the contact nozzle group".

[0156] In step S18, the control unit 100 executes a first empty discharge from the color mixing prevention corresponding nozzle (first nozzle FN1) and a second empty discharge from the other normal nozzles 21G (second nozzle FN2). The discharge amount of the first empty discharge, i.e., the first discharge amount, is a discharge amount that can discharge the color mixing liquid WL from the nozzle 21, and is greater than the discharge amount of the second empty discharge, i.e., the second discharge amount, which is a normal empty discharge. In addition, the processing of step S18 is equivalent to "discharging liquid not related to recording, i.e., empty discharge, from a plurality of nozzles based on the set empty discharge amount".

[0157] If it is determined in step S16 that there is no contact nozzle group, the control unit 100 performs second empty discharge from all nozzles in step S19 . That is, empty discharge is performed with a second empty discharge amount smaller than the first empty discharge amount for all nozzles 21 .

[0158] Effects of implementation methods

[0159] (1) The liquid ejection device 11 includes a liquid ejection unit 20, a pressurizing unit 66, a wiping unit 76, and a detecting unit 106. The liquid ejection unit 20 is configured to eject liquid from a plurality of nozzle groups N1 to N4 formed on a nozzle surface 28 to perform recording. The pressurizing unit 66 is configured to pressurize the liquid in the plurality of nozzle groups N1 to N4, thereby bulging the liquid from the plurality of nozzle groups N1 to N4. The wiping unit 76 is configured to wipe the nozzle surface 28. The detecting unit 106 is configured to detect the nozzle 21 that is contacted by the liquid droplets attached to the nozzle surface 28. The control method of the liquid ejection device 11 includes the following (a) to (e).

[0160] (a) The pressurizing unit 66 pressurizes the liquid so that the liquid swells out from the plurality of nozzle groups N1 to N4.

[0161] (b) While the operation of the pressurizing section 66 during pressurization is maintained, the wiping section 76 wipes the nozzle surface 28 and the detection section 106 performs detection.

[0162] (c) Based on the detection result by the detection unit 106 , the idle discharge amount of each of the plurality of nozzles 21 constituting the plurality of nozzle groups N1 to N4 is set.

[0163] (d) The pressurization of the pressurizing portion 66 is released.

[0164] (e) Based on the set idle discharge amount, liquid not related to recording, that is, idle discharge, is discharged from the plurality of nozzles 21 .

[0165] According to this method, since the empty discharge amount for preventing color mixing can be set according to the state of each nozzle 21, it is possible to suppress wasteful discharge of liquid from the nozzle 21.

[0166] (2) The control method of the liquid ejection device 11 includes setting the first ejection amount, which is the empty ejection amount ejected from the nozzle 21 detected by the detection unit 106, to be larger than the second ejection amount, which is the empty ejection amount ejected from other nozzles 21. According to this method, since the empty ejection amount of the nozzle 21 estimated to cause color mixing is increased, color mixing can be suppressed with a smaller empty ejection amount overall.

[0167] (3) The control method of the liquid ejection device 11 includes setting the first ejection amount, which is the empty ejection amount ejected from the nozzle 21 detected by the detection unit 106 and a predetermined number of nozzles 21 continuously adjacent to the nozzle 21, to be larger than the second ejection amount, which is the empty ejection amount ejected from the other nozzles 21. According to this method, since the empty ejection amount is increased for the nozzle 21 where color mixing may occur, color mixing can be further suppressed with a smaller empty ejection amount overall.

[0168] (4) The control method of the liquid ejection device 11 includes the following content, that is, the predetermined number is set to be larger 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 higher the possibility of color mixing in more nozzles 21 around them. By taking this into consideration, color mixing can be further suppressed.

[0169] (5) The nozzle 21 that contacts a liquid droplet attached to the nozzle surface 28 is set as the contact nozzle group NG1. The control method of the liquid ejection device 11 includes the following content, that is, when a plurality of contact nozzle groups NG1 are detected by the detection unit 106, if the number of nozzles 21 between the plurality of contact nozzle groups NG1 is less than a predetermined number, the empty ejection amount ejected from the nozzles 21 between the plurality of contact nozzle groups NG1 is set to be larger than the empty ejection amount ejected from each nozzle 21 other than the contact nozzle group NG1. According to this method, since the empty ejection amount is increased for the nozzles 21 that may cause color mixing, it is possible to suppress color mixing more with a smaller empty ejection amount overall.

[0170] (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 perform 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 pressurize the liquid in the plurality of nozzle groups N1 to N4 so that the liquid bulges out from the plurality of nozzle groups N1 to N4. The wiping unit 76 is configured to wipe the nozzle surface 28. The detection unit 106 is configured to detect the nozzle 21 that has come into contact with the liquid droplets attached to the nozzle surface 28. The control unit 100 pressurizes the pressurizing unit 66 so that the liquid bulges out from the plurality of nozzle groups N1 to N4. In addition, the control unit 100 wipes the nozzle surface 28 with the wiping unit 76 and performs detection by the detection unit 106 while maintaining the operation of the pressurizing unit 66 during pressurization. Furthermore, the control unit 100 sets the idle ejection amount of each of the plurality of nozzles 21 constituting the plurality of nozzle groups N1 to N4 based on the detection result detected by the detection unit 106. Then, the control unit 100 releases the pressurization of the pressurizing unit 66. Furthermore, the control unit 100 performs the ejection of liquid not related to recording, that is, idle ejection, from the plurality of nozzles 21 based on the set idle ejection amount. According to this configuration, since the setting of the idle ejection amount for preventing color mixing can be performed according to the state of each nozzle 21, it is possible to suppress the useless discharge of liquid from the nozzle 21.

[0171] (7) The liquid ejection unit 20 has 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 vibration plates 265. The plurality of actuators 200 are individually driven by the head drive circuit 110, which is an example of a drive circuit, so that the plurality of vibration plates 265 are partially displaced. The displaced vibration plates 265 eject liquid from the nozzles 21 corresponding to the driven actuators 200. The detection unit 106 detects the nozzles 21 contacted by the droplets attached to the nozzle surface 28 based on the residual vibration of the displaced vibration plates 265. According to this structure, since the detection unit 106 that detects the defective ejection of the nozzles 21 using the structural elements of the liquid ejection unit 20 is used to detect the nozzles 21 contacted by the droplets attached to the nozzle surface 28, it is not necessary to provide a separate detection unit 106.

[0172] (8) The pressurizing section 66 includes a liquid chamber 95, an opening and closing valve 63, and a driving section 67. The liquid chamber 95 is provided in the middle of the supply channel 25 for supplying liquid to the liquid ejection section 20, and is configured to change the volume by displacement of a membrane member 97. The opening and closing valve 63 is provided upstream of the liquid chamber 95 in the supply channel 25, and is configured to open and close the supply channel 25. The driving section 67 is configured to displace the membrane member 97. The control section 100 causes the liquid to bulge out from the plurality of nozzle groups N1 to N4 by causing the driving section 67 to displace the membrane member 97 in a direction that reduces the volume of the liquid chamber 95 while the supply channel 25 is closed by the opening and closing valve 63. According to this configuration, the liquid can be bulged out from the nozzle 21 with a simple configuration.

[0173] Change Example

[0174] This embodiment can be modified and implemented as follows. This embodiment and the following modified examples can be combined and implemented with each other within the scope of no technical contradiction.

[0175] The plurality of nozzles 21 constituting one nozzle group are connected by the liquid reservoir 272 through the cavity 264 and the liquid supply port 271. Therefore, when the plurality of attached liquids WL are in contact with the nozzle surface 28 as in the third embodiment, the smaller attached liquid WL may be pulled into the nozzle 21 by the force of the larger attached liquid WL to droop downward due to gravity. When such a phenomenon occurs, the detection unit 106 may not be able to detect the presence of the smaller attached liquid WL.

[0176] Therefore, even when one nozzle 21 to which the attached liquid WL is attached is detected by the detection unit 106, the first empty discharge based on the first discharge amount may be performed for all of the plurality of nozzles 21 connected to the nozzle 21 to which the attached liquid WL is detected through the liquid reservoir 272.

[0177] In addition, when there is another nozzle group adjacent to the nozzle group including the nozzle 21 in which the attached liquid WL is detected, since the same phenomenon may also occur in this nozzle group, it is also possible to implement the first empty ejection based on the first ejection amount for all of the multiple nozzles 21 constituting the other adjacent nozzle group.

[0178] When the detection unit 106 is configured to detect the nozzle 21 contacted by the attached liquid WL based on the residual vibration of the displaced vibration plate 265 , it is also possible to detect the presence of bubbles in the nozzle 21 or the liquid in the cavity 264 .

[0179] When detecting whether there is a nozzle 21 in contact with the attached liquid WL by the detection unit 106, if bubbles are detected in the nozzle 21 or the cavity 264, there is a possibility that the residual vibration is affected by the bubbles, and the nozzle 21 in contact with the attached liquid WL cannot be correctly detected.

[0180] Therefore, when detecting whether there is a nozzle 21 in contact with the attached liquid WL through the detection unit 106, when a nozzle 21 with bubbles or a cavity 264 is detected, the first empty ejection can be performed with the first ejection volume for all of the nozzles 21 detected to have bubbles or the multiple nozzles 21 connected to the cavity 264 through the liquid reservoir 272.

[0181] In addition, when there is another nozzle group adjacent to the nozzle group including the nozzle 21 or the cavity 264 in which the bubble is detected, since the same phenomenon may occur in the nozzle group, the first empty ejection based on the first ejection amount may be performed for all of the plurality of nozzles 21 constituting the other adjacent nozzle group. In addition, in terms of further safety, the first empty ejection based on the first ejection amount may be performed for all of the nozzles 21 in the head (unit ejection head 27 or liquid ejection head 22) in which the bubble is detected.

[0182] The setting of the empty discharge amount based on the detection result of the detection unit 106 (step S17) and the release of the pressurization of the pressurizing unit 66 may be performed either first or simultaneously. However, the other operations are performed according to Fig.28 The steps in the sequence are implemented.

[0183] The detection of the nozzles that are in contact with the liquid IL attached to the nozzle surface 28 is not limited to the structure of detecting the residual vibration of the vibration plate 265, and other detection methods may be used. For example, although the detection unit 106 used in the nozzle inspection is used in the above embodiment, it may be a camera method. In the camera method, the nozzle 21 that is in contact with the liquid attached to the nozzle surface 28 is detected by image analysis processing of analyzing an image of the nozzle surface 28 taken by a camera.

[0184] In the second embodiment, the predetermined number a is set to be larger as the number A of consecutively adjacent nozzles detected by the detection unit 106 increases. However, the predetermined number a may be set to a fixed value regardless of the number A of consecutively adjacent nozzles detected by the detection unit 106 .

[0185] The drive unit 67 may be replaced with a selector valve 69 that uses air pressure to change the membrane member 97 to pressurize the liquid in the liquid chamber 95 so that the liquid is ejected from the nozzle 21, and may be a motor that drives a pressurizing member (for example, 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 so that the liquid is ejected from the nozzle 21. In addition, the drive unit 67 may include an air cylinder, a cam, or a solenoid.

[0186] In the above embodiment, the on-off valve 63 may not be provided. For example, a check valve or a throttle valve may be provided instead of the on-off valve 63. When the head tank 64 is moved from the non-pressurized position to the pressurized position, it is sufficient as long as a closure that prevents the liquid in the liquid chamber 95 from flowing to the upstream side or a resistance that suppresses the amount of flow to the upstream side is applied is small.

[0187] The wiping portion 76 is not limited to a plate type having the scraper 77, and may be a cloth wiper.

[0188] The liquid ejecting 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 printing and dyeing device that ejects liquid such as ink onto cloth.

[0189] 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 reciprocate along the width direction X, and a liquid ejection head 22 disposed on the carriage. Then, printing is performed on the medium M by alternately performing a conveying operation of conveying the medium M to the next printing position and a printing operation of ejecting liquid droplets from the nozzle 21 of the liquid ejection head 22 during the movement of the carriage.

[0190] The liquid ejecting device 11 may be a printer having only a printing function without the image reading unit 13 .

[0191] The liquid may be a substance other than ink, for example, a coating liquid or a cleaning liquid.

[0192] The liquid ejection device 11 is not limited to a printing device that ejects ink as an example of a liquid. The liquid ejection device 11 may also be a device that ejects other liquids other than ink. As the state of the liquid ejected from the liquid ejection device 11 in the form of droplets, it is set to include a state of granular, tear-like, thread-like, and then a tail-like object is pulled out. The liquid mentioned here can be any material that can be ejected from the liquid ejection device 11. For example, the liquid can be a material in the state of a substance in a liquid phase, and is set to include a fluid body such as a liquid with high or low viscosity, a sol, a gel water, other inorganic solvents, an organic solvent, a solution, a liquid resin, and a liquid metal (metal melt). The liquid is set to include not only a liquid as a state of a substance, but also a substance in which particles of a functional material composed of a solid substance such as a pigment or metal particles are dissolved, dispersed, or mixed in a solvent. As representative examples of liquids, inks or liquid crystals as described in the above embodiments can be listed. Here, the so-called ink is a substance including various liquid compositions such as general water-based ink and oil-based ink as well as gel ink and hot melt ink. As a specific example of the liquid ejection device 11, there is a device that ejects a liquid containing electrode materials or color materials used in the manufacture of liquid crystal displays, EL (electroluminescent) displays, surface-emitting displays, color filters, etc. in a dispersed or dissolved form. The liquid ejection device 11 can also be a device that ejects biological organic matter used in the manufacture of biochips, a device that is used as a precision pipette and ejects liquid as a sample, a printing and dyeing device or a micro-dispenser, etc. The liquid ejection device 11 can also be a device that accurately ejects lubricating oil to precision equipment such as clocks or cameras, and a device that ejects transparent resin liquid such as ultraviolet curing resin onto a substrate in order to form a tiny hemispherical lens (optical lens) used in optical communication elements, etc. The liquid ejection device 11 can also be a device that ejects etching liquid such as acid or alkali in order to etch a substrate, etc. Furthermore, the liquid ejection device 11 can also be a three-dimensional printer.

[0193] Hereinafter, technical ideas and operational effects derived from the above-described embodiment and modified examples will be described.

[0194] (A) A control method for a liquid ejection device, the liquid ejection device comprising: a liquid ejection unit capable of performing 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 so that the liquid bulges out from the plurality of nozzle groups; a wiping unit capable of wiping the nozzle surface; and a detection unit capable of detecting nozzles contacted by droplets attached to the nozzle surface, the control method for the liquid ejection device comprising the following contents, namely: causing the liquid to bulge out from the plurality of nozzle groups by the pressurizing unit; wiping the nozzle surface by the wiping unit and detecting by the detection unit while maintaining the action of the pressurizing unit; setting an empty ejection amount for each of the plurality of nozzles constituting the plurality of nozzle groups based on the detection result detected by the detection unit; releasing the pressurizing by the pressurizing unit; and performing ejection of liquid not related to the recording, i.e., empty ejection, from the plurality of nozzles based on the set empty ejection amount. According to this method, since the empty discharge amount for preventing color mixing can be set according to the state of each nozzle, it is possible to suppress wasteful discharge of liquid from the nozzle.

[0195] (B) The control method of the liquid ejection device described in (A) above may also include the following content, that is, setting the first ejection amount, which is the empty ejection amount ejected from the nozzle detected by the detection unit, to be larger than the second ejection amount, which is the empty ejection amount ejected from other nozzles. According to this method, since the empty ejection amount of the nozzle estimated to cause color mixing is increased, color mixing can be suppressed with a smaller empty ejection amount overall.

[0196] (C) The control method of the liquid ejection device described in (A) or (B) above may also include the following content, that is, setting the empty ejection amount, i.e., the first ejection amount, ejected from the nozzle detected by the detection unit and a predetermined number of nozzles continuously adjacent to the nozzle to be larger than the empty ejection amount, i.e., the second ejection amount, ejected from other nozzles. According to this method, since the empty ejection amount is increased for the nozzles where color mixing may occur, color mixing can be suppressed more with a smaller empty ejection amount overall.

[0197] (D) The control method of the liquid ejection device described in any one of (A) to (C) above may also include the content that, for the predetermined number, the greater the number of consecutively adjacent nozzles detected by the detection unit, the greater the possibility of color mixing in more nozzles around it. By taking this into consideration, color mixing can be further suppressed.

[0198] (E) The control method of the liquid ejection device described in any one of (A) to (D) above may also include the following content, that is, the nozzle that contacts a liquid droplet attached to the nozzle surface is set 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 less than a specified number, the empty ejection amount ejected from the nozzles between the plurality of contact nozzle groups is set to be larger than the empty ejection amount ejected from each nozzle other than the contact nozzle group. According to this method, since the empty ejection amount is increased for the nozzles where color mixing may occur, color mixing can be suppressed more with a smaller empty ejection amount overall.

[0199] (F) A liquid ejection device, comprising: a liquid ejection unit capable of performing 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 so that the liquid bulges out from the plurality of nozzle groups; a wiping unit capable of wiping the nozzle surface; a detection unit capable of detecting nozzles in contact with liquid droplets attached to the nozzle surface; and a control unit, wherein the control unit performs the following control, i.e., the liquid bulges out from the plurality of nozzle groups by the pressurizing of the pressurizing unit, the nozzle surface is wiped by the wiping unit and the detection by the detection unit is performed while the action of the pressurizing unit is maintained, the empty ejection amount of each of the plurality of nozzles constituting the plurality of nozzle groups is set based on the detection result detected by the detection unit, the pressurizing of the pressurizing unit is released, and based on the set empty ejection amount, the liquid ejection not related to the recording, i.e., empty ejection, is performed from the plurality of nozzles. According to this configuration, since the empty discharge amount can be set according to the state of each nozzle to prevent color mixing, it is possible to suppress wasteful discharge of liquid from the nozzle.

[0200] (G) In the liquid ejection device described in (F) above, the following method may be adopted, that is, the liquid ejection unit has a plurality of actuators and a plurality of vibration plates arranged corresponding to the plurality of nozzles constituting the plurality of nozzle groups, the plurality of actuators are driven individually by a driving circuit, thereby partially displacing the plurality of vibration plates, the displaced vibration plates cause the liquid to be ejected from the nozzles corresponding to the driven actuators, and the detection unit detects the nozzles contacted by the droplets attached to the nozzle surface based on the residual vibration of the displaced vibration plates. According to this structure, since the detection unit that detects the defective ejection of the nozzles using the structural elements of the liquid ejection unit is used to detect the nozzles contacted by the droplets attached to the nozzle surface, there is no need to provide a separate detection unit.

[0201] (H) In the liquid ejection device described in (F) or (G) above, the following method may be adopted, that is, the pressurizing unit has: a liquid chamber, which is provided in the middle of a supply channel for supplying liquid to the liquid ejection unit and can change the volume by displacement of a membrane member; an opening and closing valve, which is provided in the supply channel upstream of the liquid chamber and can open and close the supply channel; a driving unit, which can displace the membrane member, and the control unit displaces the membrane member in a direction that reduces the volume of the liquid chamber by the driving unit when the supply channel is closed by the opening and closing valve, thereby causing the liquid to bulge out from the plurality of nozzle groups. According to this structure, the liquid can be bulged out from the nozzle with a simple structure.

[0202] Explanation of symbols

[0203] 11…Liquid ejection device; 12…Device body; 13…Image reading device; 14…Automatic feeding device; 15…Operation unit; 16…Medium storage unit; 17…Stacker; 18…Basket; 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…Supporting unit; 24…Liquid storage body; 24A…Liquid bag; 24B…Casing; 25…Supply flow channel; 26…Retaining frame; 27…Unit ejection head; 28…Nozzle surface; 29…Check valve; 30…Conveying unit; 31…Feeding roller; 33…Conveying roller; 34…Conveying belt; 37…Supporting unit 40…Maintenance unit; 41…Cover; 42…Waste liquid flow channel; 43…Decompression unit; 44…Discharge mechanism; 45…Cover moving mechanism; 50…Waste liquid storage body; 51…Retaining frame; 60…Liquid supply mechanism; 61…Sub-tank; 62…Self-sealing valve; 63…Opening and closing valve; 64…Head tank; 65…Flow channel valve; 66…Pressure unit; 67…Drive unit; 67M…Motor; 67P…Pump; 68…Pressure sensor; 69…Selection valve; 69A…Pressure tank; 70…Motor; 71…First air flow channel; 72…Second air flow channel; 73…Third air flow channel; 76…Wiping unit; 77…Scraper; 78…Motor; 79…Discharge flow channel; 80…Waste liquid collection Na part; 81...opening and closing valve; 82...motor; 83...discharge flow channel; 84...opening and closing valve; 91...liquid chamber; 91a...bottom surface; 92...air chamber; 93...membrane member; 94...working pressure regulating spring; 95...liquid chamber; 95a...bottom surface; 96...air chamber; 97...membrane member; 98...working pressure regulating spring; 100...control part; 101...computer; 102...printing control part; 103...nozzle inspection part; 105...storage part; 106...detection part; 110...head driving circuit as an example of driving circuit; 111...driving signal generating part; 112...discharging abnormality detecting part; 113...switching part; 130...discharging unit; 200...actuator; 201…lower electrode; 202…upper electrode; 203…piezoelectric body; 264…cavity; 265…vibration plate; 266…cavity plate; 271…liquid supply port; 272…liquid reservoir; N1~N4…nozzle group; SL…solenoid; M…medium; IL…liquid; WL…attached liquid (mixed color liquid); MS…curved liquid surface; EL…bulge; D…discharge part; Vin…drive signal; SI…bus data; COM…drive waveform signal; Vout…residual vibration signal; NG1…contact nozzle group; FN1…first nozzle; FN2…second nozzle; a…predetermined number; K…specified number; X…width direction; Y…conveying direction; Z…vertical direction.

Claims

1. A method for controlling a liquid ejection device, characterized in that: The liquid ejection device comprises: a liquid ejecting section capable of performing recording by ejecting liquid from a plurality of nozzle groups formed on a nozzle face; a pressurizing unit capable of pressurizing the liquid in the plurality of nozzle groups so as to cause the liquid to bulge out from the plurality of nozzle groups; a wiping portion capable of wiping the nozzle surface; a detection unit capable of detecting the nozzle contacted by the droplets attached to the nozzle surface, The control method of the liquid ejection device includes the following contents, namely: The liquid is caused to bulge out from the plurality of nozzle groups by the pressurizing of the pressurizing unit; while the operation of the pressurizing portion during the pressurizing is maintained, wiping the nozzle surface by the wiping portion and detecting by the detecting portion are performed; Based on the detection result detected by the detection unit, the idle ejection amount of each of the plurality of nozzles constituting the plurality of nozzle groups is set; releasing the pressurization of the pressurizing portion; Based on the set idle discharge amount, the liquid not related to the recording, that is, idle discharge, is discharged from the plurality of nozzles.

2. The control method of the liquid ejection device according to claim 1, characterized in that: The method includes setting a first discharge amount, which is an idle discharge amount discharged from the nozzle detected by the detection unit, to be larger than a second discharge amount, which is an idle discharge amount discharged from other nozzles.

3. The control method of the liquid ejection device according to claim 1, characterized in that: The method includes setting a first ejection amount, which is an idle ejection amount ejected from a nozzle detected by the detection unit and a predetermined number of nozzles continuously adjacent to the nozzle, to be larger than a second ejection amount, which is an idle ejection amount ejected from other nozzles.

4. The control method of the liquid ejection device according to claim 3, characterized in that: This includes the following content: the predetermined number is set to be larger as the number of consecutively adjacent nozzles detected by the detection unit increases.

5. The control method of the liquid ejection device according to claim 3 or claim 4, characterized in that: The present invention includes the following contents, namely, setting a nozzle that contacts a liquid droplet attached to the nozzle surface as a contact nozzle group, and in a case where a plurality of the contact nozzle groups are detected by the detection unit, if the number of nozzles between the plurality of the contact nozzle groups is less than a specified number, setting the empty ejection amount ejected from the nozzles between the plurality of the contact nozzle groups to be greater than the empty ejection amount ejected from each nozzle other than the contact nozzle group.

6. A liquid ejection device, characterized in that: have: a liquid ejecting section capable of performing recording by ejecting liquid from a plurality of nozzle groups formed on a nozzle face; a pressurizing unit capable of pressurizing the liquid in the plurality of nozzle groups so as to cause the liquid to bulge out from the plurality of nozzle groups; a wiping portion capable of wiping the nozzle surface; a detection unit capable of detecting a nozzle in contact with a liquid droplet attached to the nozzle surface; Control Department, The control unit performs the following control, namely, The liquid is caused to bulge out from the plurality of nozzle groups by the pressurization of the pressurizing unit. The nozzle surface is wiped by the wiping portion and the detection is performed by the detection portion while the operation of the pressurizing portion during the pressurizing is maintained. Based on the detection result detected by the detection unit, the idle ejection amount of each of the plurality of nozzles constituting the plurality of nozzle groups is set; releasing the pressurization of the pressurizing portion, Based on the set idle discharge amount, the liquid not related to the recording, that is, idle discharge, is discharged from the plurality of nozzles.

7. The liquid ejection device according to claim 6, wherein: The liquid ejection unit includes 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 are individually driven by a driving circuit, thereby partially displacing the plurality of vibration plates. The displaced vibration plate causes the liquid to be ejected from the nozzle corresponding to the driven actuator. The detection unit detects the nozzle that the droplet attached to the nozzle surface has contacted based on the residual vibration of the displaced vibration plate.

8. The liquid ejection device according to claim 6, wherein: The pressurizing part has: a liquid chamber provided in the middle of a supply channel for supplying liquid to the liquid ejection portion and capable of changing its volume by displacement of a membrane member; an on-off valve provided in the supply flow channel at an upstream position relative to the liquid chamber and capable of opening and closing the supply flow channel; a driving unit capable of causing the membrane member to be displaced, The control unit causes the liquid to bulge out from the plurality of nozzle groups by causing the drive unit to displace the membrane member in a direction that reduces the volume of the liquid chamber in a state in which the supply flow path is closed by the on-off valve.

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