Liquid discharge apparatus

Abstract

To provide a liquid discharge device capable of detecting whether or not an electrode in a cap is correctly mounted.SOLUTION: The liquid discharge apparatus 1 includes a discharge head 10, an electrode housing body 51, a counter electrode 52, a voltage application device 66, and a control device 30, and the control device 30 determines the state of the nozzle 11 based on a change in the voltage of the counter electrode 52 when the liquid is discharged from the discharge head 10 in a state where the voltage is applied between the discharge head 10 and the counter electrode 52. And posture determination processing of determining a mounting posture of the counter electrode 52 with respect to the electrode support 51 based on a voltage of the counter electrode 52 when the liquid is ejected from the ejection head 10 in a state where a voltage is applied between the ejection head 10 and the counter electrode 52.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, a liquid ejection device such as that described in Patent Document 1 has been known. This liquid ejection device is equipped with an inspection device that inspects whether ink is ejected normally from the nozzles. This inspection device applies a voltage between the head that ejects ink and an electrode provided on a cap that receives the ink ejected from the head, and detects abnormal ink ejection based on a voltage change that occurs at the electrode when ink is ejected from the head in this state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-226619 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, the cap that receives the ink also contains foam to absorb the ink. Foam is a consumable item whose absorbency decreases as it receives more ink, and so it may need to be replaced by the user. When a user replaces the components inside the cap, including the foam, there is a possibility that the new components will not be installed correctly inside the cap. For example, the foam may be installed at an angle or floating above the bottom of the cap.

[0005] On the other hand, because the foam with ink attached is conductive, the foam in contact with the electrode itself also functions as an electrode. If the foam's posture changes from normal as described above, the electric field between the head and the electrode (including the foam) also changes from normal. This affects ink ejection detection, and may result in incorrect detection.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present disclosure to provide a liquid ejection device that can detect whether or not an electrode in a cap is correctly attached. [Means for solving the problem]

[0007] A liquid ejection device according to a first aspect of the present disclosure comprises an ejection head having a nozzle surface on which nozzles for ejecting liquid onto a print medium are formed, an electrode housing arranged opposite the nozzle surface of the ejection head in a predetermined region, a counter electrode housed in a removably attachable / detachable manner in the electrode housing, a voltage application device that applies a predetermined voltage between the ejection head and the counter electrode, and a control device, wherein the control device executes an ejection determination process that determines the state of the nozzle based on a change in voltage of the counter electrode when liquid is ejected from the ejection head while a voltage is applied between the ejection head and the counter electrode by the voltage application device, and an attitude determination process that determines the mounting attitude of the counter electrode relative to the electrode support based on the voltage of the counter electrode when liquid is ejected from the ejection head while a voltage is applied between the ejection head and the counter electrode by the voltage application device. [Effects of the Invention]

[0008] According to the liquid ejection device according to the present disclosure, it is possible to detect whether the electrodes in the cap are correctly attached. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a liquid ejection device according to the present disclosure. [Figure 2]FIG. 2 is a block diagram showing the functional configuration of the liquid ejection device. [Figure 3] FIG. 3 is a schematic diagram showing a configuration including a maintenance unit used in ejection determination and attitude determination. [Figure 4] FIG. 4 is a perspective view showing a specific configuration example of the maintenance unit. [Figure 5] FIG. 5 is a cross-sectional view showing a specific example of the configuration of the maintenance unit. [Figure 6] FIG. 6A is a graph showing changes in voltage values ​​detected by the detection substrate, and FIG. 6B is a graph showing an example of the relationship between the distance between the ejection head and the counter electrode and the detected voltage. [Figure 7] FIG. 7A is a schematic diagram showing a state in which the counter electrode is floating, and FIG. 7B is a graph for explaining the determination of whether or not the counter electrode is floating. [Figure 8] FIG. 8A is a schematic diagram showing a state in which the counter electrode is tilted, and FIG. 8B is a graph for explaining the determination of whether or not the counter electrode is tilted. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a liquid ejection device according to the present disclosure will be specifically described with reference to the drawings. Note that, in the following, the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant description will be omitted.

[0011] (Configuration of liquid ejection device) 1 is a schematic diagram of a liquid ejection device 1 according to the present disclosure. The liquid ejection device 1 prints an image on a print medium A using liquid ejected from an ejection head 10 based on image data. An example of such a liquid ejection device 1 applied to an inkjet printer that ejects ink will be described below.

[0012] The liquid ejection device 1 is a serial head type, and alternates between a process of ejecting ink of multiple colors to form an image while the ejection head 10 moves (scans) and a process of transporting the print medium A. Note that, hereinafter, the direction in which the ejection head 10 moves back and forth is referred to as a first direction (or left-right direction), and the direction in which the print medium A is transported, which is perpendicular to the first direction, is referred to as a second direction (or front-back direction). Furthermore, a direction perpendicular to both the first and second directions is referred to as a third direction (or up-down direction). However, the arrangement direction of the liquid ejection device 1 is not limited to this.

[0013] The ejection head 10 is housed in a housing 2 of the liquid ejection device 1. The ejection head 10 has a nozzle surface 12 in which a plurality of nozzles 11 are opened, which eject liquid onto the print medium A based on print data. On the nozzle surface 12, the plurality of nozzles 11 are lined up, for example, in the front-to-rear direction to form a nozzle row, and further, this nozzle row is formed in multiple rows in the left-to-right direction.

[0014] The liquid ejection device 1 includes a platen 14 disposed opposite the ejection head 10. The platen 14 is positioned below the ejection head 10 at a predetermined distance, and supports the print medium A from below with its flat upper surface.

[0015] The liquid ejection device 1 is equipped with a transport device 15 that transports the print medium A on a platen 14. The transport device 15 has, for example, two transport rollers 16 and a transport motor. The two transport rollers 16 are arranged at a distance from each other in the front and rear with the platen 14 sandwiched between them, and are connected to the rotating shaft of the transport motor via a reducer. Therefore, when the transport motor is driven, the two transport rollers 16 rotate about their axes, transporting the print medium A on the platen 14 in the front-to-rear direction.

[0016] The liquid ejection device 1 is equipped with a moving device 18 that moves the ejection head 10 back and forth in the left and right direction. The moving device 18 has a carriage 19, two guide rails 20, an endless belt 21, and a moving motor. The carriage 19 supports the ejection head 10 and moves back and forth in the left and right direction together with the ejection head 10. The two guide rails 20 extend left and right across the platen 14 and are arranged spaced apart in the front and back with the ejection head 10 sandwiched between them. The two guide rails 20 support the carriage 19 so that it can move (scan) in the left and right direction.

[0017] The endless belt 21 is wound around two pulleys 22 provided near the left and right ends of one of the guide rails 20, and is connected to the carriage 19 at a predetermined location. The movement motor has a rotation shaft connected to either the left or right pulley 22 via a reducer. Therefore, in this movement device 18, when the movement motor is driven to rotate, the endless belt 21 runs, and the carriage 19 supporting the discharge head 10 moves left and right along the guide rail 20.

[0018] A maintenance area 23 is provided in a predetermined area within the housing 2, within the range in which the carriage 19 can be moved by the moving device 18. In the example of Fig. 1, the maintenance area 23 is provided at a position away to the right of the platen 14. A maintenance unit 50 including an electrode container 51 and a counter electrode 52 is provided in the maintenance area 23.

[0019] The electrode container 51 is disposed in the maintenance area 23 facing the nozzle surface 12 of the ejection head 10, and the counter electrode 52 is housed in the electrode container 51 so as to be freely attachable and detachable. The liquid ejection device 1 positions the ejection head 10 in this maintenance area 23, and can perform an ejection determination process relating to the state of the nozzles 11 and an attitude determination process relating to the mounting attitude of the counter electrode 52, as will be described later. The configuration of the maintenance unit 50 will be described in detail later.

[0020] The liquid ejection device 1 is equipped with a plurality of tanks 24 that store ink of each color to be supplied to the ejection head 10. These tanks 24 are housed inside the housing 2 by opening an openable cover provided on the housing 2. The liquid ejection device 1 of the present disclosure uses a total of four colors of ink, for example, colors such as cyan, yellow, magenta, and black, and is equipped with four tanks 24 accordingly. One end of a flexible tube 25 is connected to each tank 24, and the other end is connected to an ink supply port of the ejection head 10, and ink from each tank 24 is sent to the ejection head 10 through the tube 25.

[0021] The type of ink is not limited to the above. The ink used in the liquid ejection device 1 according to the present disclosure may be any ink that can be charged to a predetermined amount of charge in the form of droplets ejected from the nozzles 11 by a voltage application device 66 described below.

[0022] Fig. 2 is a block diagram showing the functional configuration of the liquid ejection device 1. As shown in Fig. 2, the liquid ejection device 1 has a functional configuration mainly made up of hardware, which includes a control device 30, a storage device 31 connected to the control device 30, an interface 32, and a head driving device 33. The control device 30 is also connected to the above-mentioned transport device 15 and moving device 18, and is further connected to a display device 34.

[0023] The control device 30 is, for example, a computer, and includes a processor such as an MPU, or an integrated circuit such as an ASIC. The storage device 31 is a memory accessible from the control device 30, and includes, for example, RAM and ROM. The ROM stores computer programs and data for various data processing operations. The RAM also temporarily stores image data included in print jobs and various data used for calculations by the control device 30. Therefore, the control device 30 controls the operation of each part of the liquid ejection device 1 by executing a computer program while referencing the data stored in the storage device 31.

[0024] The interface 32 is a connection device that connects the control device 30 to external devices of the liquid ejection device 1. Examples of external devices include other computers, communication networks, recording media, displays, and other liquid ejection devices. The liquid ejection device 1 obtains a print job including image data and print setting information from an external device, such as a computer, via this interface 32.

[0025] The head driver 33 has a head driver circuit electrically connected to the actuators that the ejection head 10 has for each nozzle 11, and controls the operation of each actuator based on instructions from the control device 30. That is, the control device 30 outputs control signals for driving the actuators to the head driver circuit, and the head driver circuit generates drive signals based on the input control signals and outputs these drive signals to each actuator. Therefore, the liquid ejection device 1 can control whether or not to eject ink for each nozzle 11, and can also control the volume and timing of ejected ink droplets.

[0026] The transport device 15 has a transport drive circuit electrically connected to the transport motor described above, and the operation of the transport motor is controlled by the control device 30 via the transport drive circuit. This allows the transport device 15 to transport the print medium A on the platen 14 intermittently or continuously in the forward / backward direction, which is the second direction, and to stop and hold the print medium A at a predetermined position on the platen 14.

[0027] The movement device 18 has a movement drive circuit electrically connected to the movement motor described above, and the operation of the movement motor is controlled by the control device 30 via the movement drive circuit. This allows the movement device 18 to move the carriage 19 supporting the ejection head 10 in the left and right direction, which is the first direction, at different speeds, and to stop the carriage 19 at any position within its movable range. Therefore, the ejection head 10 mounted on the carriage 19 is moved back and forth in the left and right direction relative to the print medium A by the movement device 18, or is positioned above the maintenance area 23.

[0028] The display device 34 has a liquid crystal display or the like, and displays (outputs) various information related to the settings and operation of the liquid ejection device 1 so that the user can visually recognize it. The display device 34 may further have a touch panel and function as an input device. The display device 34 functioning as an input device receives operational inputs from the user.

[0029] The liquid ejection device 1 further includes, as functional components made up of software, a print processing unit 40, an ejection determination processing unit 41, and an attitude determination processing unit 42. Each of these processing units 40 to 42 functions when the control device 30 executes a computer program stored in the storage device 31.

[0030] Of these, the printing processing unit 40 performs a printing process in which droplets are ejected from the nozzles 11 of the ejection head 10 to form an image on the printing medium A based on printing data generated by performing halftone processing on the image data, while the ejection head 10 and the printing medium A are moved relative to each other using the moving device 18.

[0031] The discharge determination processing unit 41 executes a discharge determination process for determining the state of the nozzle 11. That is, the control device 30 discharges liquid from the nozzle 11 of the discharge head 10 while applying a voltage between the discharge head 10 and the counter electrode 52 using a voltage application device 66 (described later), and determines the state of the nozzle 11 based on the change in the voltage of the counter electrode 52 at this time.

[0032] The attitude determination processing unit 42 executes an attitude determination process for determining the mounting attitude of the counter electrode 52 relative to the electrode container 51. That is, the control device 30 applies a voltage between the discharge head 10 and the counter electrode 52 by the voltage application device 66, discharges liquid from the nozzle 11 of the discharge head 10, and determines the attitude of the counter electrode 52 based on the voltage of the counter electrode 52 at this time.

[0033] As can be seen from the above, the attitude determination process uses the voltage of the opposing electrode 52 obtained in the discharge determination process to determine the attitude. The discharge determination process and the attitude determination process will be described in detail later.

[0034] (Details of the configuration for ejection judgment and posture judgment) An example of the configuration related to discharge determination and attitude determination in the liquid discharge device 1 will be described in more detail with reference to Figures 3 to 5. Figure 3 is a schematic diagram showing a configuration including a maintenance unit 50 used in each determination. Figure 4 is a perspective view showing a specific example of the configuration of the maintenance unit 50 arranged in the maintenance area 23. Figure 5 is a schematic cross-sectional view showing a specific example of the configuration of the maintenance unit 50.

[0035] 3, the ejection head 10 provided in the liquid ejection device 1 has a CR (carriage) board 60, a damper 61, and a front end 62. Of these, the CR board 60 is equipped with a head drive circuit for the head drive device 33 described above, and is driven based on a control signal from the control device 30. The damper 61 is a sub-tank-like part that temporarily stores ink between the tank 24 and the front end 62.

[0036] The front end 62 is a flow path part made up of multiple laminated thin metal plates with through holes and recesses. Therefore, flow paths (individual flow paths, a common flow path, etc.) for ink supplied from the damper 61 are formed inside the front end 62. A plurality of nozzles 11 that communicate with the flow paths are opened on the lower surface of the front end 62, and actuators are provided on the upper surface of the front end 62 corresponding to the individual flow paths that communicate with each nozzle 11. The operation of these actuators is controlled by a head drive circuit mounted on the CR board 60.

[0037] A main board 64 that constitutes the control device 30 is connected to the CR board 60. The main board 64 includes a calculation unit such as an MPU or ASIC, and a storage unit such as a ROM or RAM, and is mainly responsible for executing the printing process by the print processing unit 40 of the liquid ejection device 1.

[0038] A detection board 65, which together with the main board 64 constitutes the control device 30, is connected to the main board 64, and the detection board 65 is also connected to the maintenance unit 50. The detection board 65 includes a calculation unit such as an MPU or ASIC, and a storage unit such as a ROM or RAM, and is mainly responsible for executing the processes of the discharge determination processing unit 41 and the attitude determination processing unit 42 of the liquid discharge device 1.

[0039] A voltage application device 66 is also mounted on the detection board 65. The voltage application device 66 is configured with a circuit including, for example, a Zener diode, and is capable of applying a predetermined constant voltage to the counter electrode 52. As shown in FIG. 3, the CR board 60 and the front end 62 of the ejection head 10 are connected to ground. Therefore, when the voltage application device 66 is operated with the ejection head 10 and the counter electrode 52 positioned vertically opposite each other in the maintenance area 23, a predetermined voltage V is applied to the counter electrode 52, with the nozzle surface 12 of the ejection head 10 as the reference. The value of the voltage V of the counter electrode 52 is also input to the detection board 65.

[0040] 4 and 5, an example of the maintenance unit 50 will be described in more detail. The maintenance unit 50 has a base box 55 that is installed in the maintenance area 23 of the housing 2. The base box 55 has a flat rectangular parallelepiped shape and is open at the top. A cap holder 56 is disposed within the base box 55. The cap holder 56 also has a flat rectangular parallelepiped shape and is open at the top.

[0041] A rubber-plate-like base plate 57 is disposed at the inner bottom of the cap holder 56, and a cap 59 is disposed on the upper surface of the base plate 57. The cap 59 has a flat rectangular parallelepiped shape and has a rectangular bottom wall 59a and four side walls 59b extending upward from the four sides thereof, and is open at the top. The cap 59 forms the electrode container 51 described above, and the counter electrode 52 is contained and supported within the cap 59.

[0042] The counter electrode 52 includes a foam material 53 and a regulating member 54. The foam material 53 is made of, for example, a sponge, and is capable of absorbing a predetermined amount of ink ejected from the nozzles 11. The foam material 53 shown in FIG. 4 has a flat rectangular parallelepiped shape.

[0043] The restricting member 54 is made of a conductive metal or a conductive resin, and is a rigid member having higher rigidity than the foam material 53. The restricting member 54 supports the foam material 53 and engages it within the cap 59 (electrode container 51). The restricting member 54 shown in Fig. 4 is made up of four side wall portions 54a corresponding to the four side surfaces of the foam material 53, a first bridge portion 54b provided between the upper ends of one of two pairs of opposing side wall portions 54a, and a second bridge portion 54c provided between the upper ends of the other pair of side wall portions 54a.

[0044] The width of the first bridge portion 54b is sufficiently smaller than the dimension of the foam material 53 in the corresponding direction. Similarly, the width of the second bridge portion 54c is also sufficiently smaller than the dimension of the foam material 53 in the corresponding direction. Therefore, a relatively large opening 54d is formed in the upper part of the restricting member 54 in a portion other than the portions where the first bridge portion 54b and the second bridge portion 54c are provided, and the foam material 53 is exposed through this opening 54d. Therefore, ink ejected from the nozzles 11 adheres to the foam material 53 through the opening 54d and is absorbed. Note that in the example of FIG. 4, four openings 54d are formed in a matrix.

[0045] Note that foam material 53 can be replaced by the user because its ink absorption capacity decreases after it has absorbed a certain amount of ink. For example, foam material 53 is configured to be detachable from cap 59 while supported by regulating member 54. In other words, foam material 53 and regulating member 54 are integrated, and can be inserted into or removed from cap 59 through the opening at the top of the cap.

[0046] The maintenance unit 50 further includes an electrode pin 58. The electrode pin 58 is needle-shaped and made of a conductive material. The electrode pin 58 penetrates from below through the bottom of the base box 55, the bottom of the cap holder 56, the base plate 57, and the cap 59 (electrode container 51), and its tip (upper end) is in contact with the foam material 53.

[0047] Furthermore, the portion of the electrode pin 58 that protrudes downward from the base box 55 is connected to the detection board 65 via an electric wire. Therefore, a predetermined voltage is applied to the counter electrode 52, which is made up of the foam material 53 and the restricting member 54, by the voltage application device 66 of the detection board 65 via the electrode pin 58, and the voltage of the counter electrode 52 is detected by the detection board 65.

[0048] (Discharge determination process) Next, we will explain the discharge determination process performed by the liquid discharger 1 equipped with the maintenance unit 50 described above. The discharge determination process is started, for example, when an execution command is input by the user via the display device 34 having a touch panel. In the discharge determination process, the liquid discharger 1 first uses the movement device 18 to move the discharge head 10 to the maintenance area 23. In this state, the voltage application device 66 applies a predetermined voltage V to the counter electrode 52, generating a potential difference across the discharge head 10. Here, the foam material 53 soaked in ink and the regulating member 54 made of a conductive material are electrically conductive to each other, so they together form the counter electrode 52 and are at the same potential.

[0049] In this state, ink is ejected from a predetermined nozzle 11 of the ejection head 10. This ejects charged ink droplets. As the charged ink droplets move from the ejection head 10 to the counter electrode 52, a change occurs in the voltage (potential) of the counter electrode 52.

[0050] 6A is a graph showing the change in voltage value detected by the detection substrate 65 as charged ink droplets are ejected. Note that FIG. 6A shows values ​​obtained by processing, such as differentiating the voltage value of the opposing electrode 52. In this example, when charged ink droplets are ejected, the value related to the voltage of the opposing electrode 52 on the detection substrate 65 changes, increasing once, passing through a maximum value, then decreasing sharply, passing through a minimum value, and then returning to its original state. The difference between the maximum value and the minimum value at this time is taken as the detection voltage.

[0051] In the ejection determination process, it is determined for each nozzle 11, one by one, whether or not this detected voltage is greater than a predetermined threshold. If the detected voltage is greater than the threshold, the nozzle 11 is determined to be normal. On the other hand, if the detected voltage is equal to or less than the threshold, the nozzle 11 is determined to be abnormal, or the ejection determination process is retried. In this way, the liquid ejection device 1 ejects ink from the nozzle 11 with a predetermined voltage applied between the ejection head 10 and the opposing electrode 52, and determines the state of the nozzle 11 based on the change in voltage of the opposing electrode 52 at this time.

[0052] (Posture determination processing) Next, the attitude determination process performed by the liquid ejection device 1 will be described. In the liquid ejection device 1 according to the present disclosure, the counter electrode 52 is detachable from the electrode housing 51 (cap 59), and the user can replace the counter electrode 52. Therefore, there is a possibility that the counter electrode 52 may be attached to the electrode housing 51 in a state where it is floating or tilted as a whole. Therefore, in the present disclosure, an attitude determination process is performed to detect such "floating" or "tilt" of the counter electrode 52. The attitude determination process is started, for example, when an execution command is input by the user via the display device 34 having a touch panel.

[0053] The counter electrode 52 being "floating" means that the upper surface of the counter electrode 52 is in the correct position (for example, parallel to the nozzle surface 12 of the ejection head 10), but the distance between the ejection head 10 and the counter electrode 52 is closer than appropriate (see FIG. 7A). The counter electrode 52 being "floating" occurs when the counter electrode 52 is not fitted to the correct position in the electrode container 51. The counter electrode 52 being "tilted" means that the upper surface of the counter electrode 52 is not in the correct position, but is, for example, tilted relative to the nozzle surface 12 (see FIG. 8A).

[0054] Incidentally, the voltage value of the counter electrode 52 detected by the detection substrate 65 (the value of the detection voltage described above) varies depending on the distance between the ejection head 10 and the counter electrode 52. More specifically, the detection voltage varies depending on the distance between the nozzle 11 in the ejection head 10 that ejects charged ink and the portion of the counter electrode 52 that faces the nozzle 11. FIG. 6B is a graph showing an example of the relationship between the distance between the ejection head 10 and the counter electrode 52 and the detection voltage. In the example shown in this graph, the detection voltage tends to increase as the distance between the ejection head 10 and the counter electrode 52 decreases. The liquid ejection device 1 according to the present disclosure utilizes this correlation between distance and voltage to determine whether the posture of the counter electrode 52 is appropriate.

[0055] 7A and 7B, detection of floating of the counter electrode 52 will be described. In detecting floating, the liquid ejection device 1 determines the separation distance of the counter electrode 52 from the nozzle surface 12, i.e., the presence or absence of floating, based on the result of comparing the voltage value (detection voltage) of the counter electrode 52 with a predetermined threshold Va. This threshold Va can be set as a voltage value detected when the distance between the ejection head 10 and the counter electrode 52 is a predetermined distance Da that deviates from the appropriate distance.

[0056] In the example shown in FIG. 7A, the counter electrode 52 (foam material 53 and restricting member 54) is floating relative to the electrode container 51 (cap 59). In this case, the distance D1 between the nozzle surface 12 of the ejection head 10 and the upper surface of the counter electrode 52 is smaller than the appropriate distance Da. Therefore, the detected voltage V1 at this time is equal to or greater than a predetermined threshold value Va. Therefore, when the liquid ejection device 1 detects a detected voltage equal to or greater than the threshold value Va, it determines that the counter electrode 52 is floating. However, when the detected voltage is less than the threshold value Va, it determines that the counter electrode 52 is not floating.

[0057] The number of nozzles 11 that eject ink to determine whether or not there is a lift may be one or more. When using multiple nozzles 11, ink is ejected from each nozzle 11 at different times, and the average of the detected voltages when ink is ejected from each nozzle 11 is compared with the threshold value Da.

[0058] 8A and 8B, detection of the tilt of the counter electrode 52 will be described. In detecting tilt, the liquid ejection device 1 determines whether or not the counter electrode 52 is tilted with respect to the nozzle surface 12 based on the difference ΔV between the detected voltage when ink is ejected from one nozzle 11 and the detected voltage when ink is ejected from another nozzle 11. For example, the voltage difference ΔV is compared with a predetermined threshold Vb, and if the potential difference ΔV is equal to or greater than the threshold Vb, it is determined that there is tilt, and if the potential difference ΔV is less than the threshold Vb, it is determined that there is no tilt.

[0059] 8A, the counter electrode 52 is mounted at an angle relative to the electrode container 51, and therefore the upper surface of the counter electrode 52 is inclined relative to the nozzle surface 12. In this case, the distance D2 between the counter electrode 52 and the nozzle surface 12 at the position of one nozzle 11 is different from the distance D3 between the counter electrode 52 and the nozzle surface 12 at the position of another nozzle 11. Therefore, the detected voltage V2 when ink is ejected from the former nozzle 11 is different from the detected voltage V3 when ink is ejected from the latter nozzle 11.

[0060] The liquid ejection device 1 compares the difference ΔV between the voltages V2 and V3 with a predetermined threshold Vb, and determines that a gradient exists if the potential difference ΔV is equal to or greater than the threshold Vb, and determines that no gradient exists if the potential difference ΔV is less than the threshold Vb.

[0061] In determining whether or not there is tilt, the difference ΔV in the detected voltages when ink is ejected from at least two nozzles 11 is compared with the threshold value Vb as described above, and therefore the accuracy of the determination can be improved by selecting nozzles 11 that are located as far apart as possible from each other. Therefore, for example, nozzles located at one end of a nozzle row and nozzles located at the other end can be selected. Alternatively, among multiple nozzle rows, nozzles 11 included in a nozzle row located at one end and nozzles 11 included in a nozzle row located at the other end can be selected.

[0062] (Variation) As described above, the counter electrode 52 of the liquid ejection device 1 according to the present disclosure is composed of a foam material 53 and a regulating member 54. The regulating member 54 is composed of a rigid member that is more rigid than the foam material 53. Therefore, when performing the posture determination process, the nozzle 11 that faces the regulating member 54 (for example, the first bridge portion 54b or the second bridge portion 54c) in the maintenance area 23 may be selected as the nozzle 11 that ejects ink. Because the regulating member 54 is more rigid than the foam material 53 and therefore has a stable shape, posture determination can be performed with higher accuracy by using the detection voltage when ink is ejected from the nozzle 11 and lands on the regulating member 54.

[0063] The maintenance unit 50 according to the present disclosure also includes a foam material 53 housed in a cap 59. Therefore, the ejection head 10 may be disposed in the maintenance area 23, and the actuator may be driven to eject ink, thereby performing a flushing process to straighten the meniscus of the nozzles 11 and discard dried ink. Furthermore, a mechanism for moving the cap 59 up and down in a third direction may be provided to allow the cap 59 to be tightly attached to the nozzle surface 12, and a pump that creates negative pressure inside the cap 59 may be connected to perform a purging process to suck and discard ink from the nozzles 11 in the nozzle surface 12 sealed by the cap 59. In this way, the maintenance unit 50 according to the present disclosure can be configured to perform a flushing process and / or a purging process in addition to the ejection determination process and the attitude determination process.

[0064] The liquid ejection device 1 according to the present disclosure is provided with a display device 34. Therefore, if it is determined in the posture determination process that there is an abnormality in the mounting posture of the counter electrode 52, information regarding the abnormality may be displayed on this display device 34. Of course, various information regarding various other processes executed by the liquid ejection device 1 may also be displayed to the user.

[0065] As described above, the liquid ejection device 1 according to the present disclosure can determine whether the counter electrode 52 is properly attached by the posture determination process. Therefore, if the counter electrode 52 is not properly attached, the user can be prompted to reattach it. This ensures that the counter electrode 52 is properly attached to the electrode container 51, allowing the ejection determination process to be performed with high accuracy. Furthermore, since the posture determination process can be performed using information (detected voltage) used in the ejection determination process, no dedicated hardware configuration is required for the posture determination process. Therefore, even if the posture determination function is added, a significant increase in cost and an increase in size of the liquid ejection device 1 can be suppressed. [Industrial Applicability]

[0066] The present disclosure can be applied to a liquid ejection device. [Explanation of symbols]

[0067] 1 Liquid discharge device 10 Discharge head 11 nozzles 12 Nozzle surface 23 Maintenance Area 30 Control device 41 Discharge determination processing unit 42 Attitude determination processing unit 51 Electrode container 52 Counter electrode 53 Foam material 54 Regulatory member 66 Voltage application device

Claims

1. an ejection head having a nozzle surface on which nozzles for ejecting liquid onto a print medium are formed; an electrode container disposed opposite the nozzle surface of the ejection head in a predetermined region; a counter electrode detachably housed in the electrode housing; a voltage application device that applies a predetermined voltage between the ejection head and the counter electrode; a control device; The control device an ejection determination process for determining the state of the nozzle based on a change in voltage of the counter electrode when liquid is ejected from the ejection head while a voltage is applied between the ejection head and the counter electrode by the voltage application device; and executing an attitude determination process for determining an attachment attitude of the counter electrode relative to the electrode support, based on a voltage of the counter electrode when liquid is ejected from the ejection head, in a state in which a voltage is applied between the ejection head and the counter electrode by the voltage application device. Liquid discharge device.

2. the control device, in the attitude determination process, determines the inclination of the opposing electrode with respect to the nozzle surface based on a difference between a voltage value of the opposing electrode when liquid is ejected from one nozzle and a voltage value of the opposing electrode when liquid is ejected from another nozzle. The liquid ejection device according to claim 1 .

3. the control device determines a distance between the nozzle surface and the opposing electrode based on a comparison result between a voltage value of the opposing electrode when liquid is ejected from the nozzle and a predetermined threshold value in the attitude determination process; The liquid ejection device according to claim 1 .

4. the control device uses, as the voltage value to be compared with the predetermined threshold, an average value obtained from each voltage value of the opposing electrode when liquid is ejected from each of two or more nozzles; The liquid ejection device according to claim 3 .

5. the counter electrode has at least a portion made of a rigid member made of metal or conductive resin, the control device performs the attitude determination process based on a voltage of the opposing electrode when liquid is ejected from a nozzle opposing the rigid member in the predetermined region. The liquid ejection device according to claim 1 .

6. Further provided is a display device for displaying predetermined information to the outside, When the control device determines that there is an abnormality in the wearing posture in the posture determination process, the control device causes the display device to display information regarding the abnormality. The liquid ejection device according to claim 1 .

7. the counter electrode has a foam material that receives the liquid ejected from the nozzle, and a conductive regulating member that regulates the foam material; The liquid ejection device according to claim 1 .

8. The regulating member is made of a conductive resin. The liquid ejection device according to claim 7 .

Images