Inkjet recording device

Abstract

To mitigate a constraint condition imposed on air that is discharged to the outside.SOLUTION: An inkjet recording device I comprises: an enclosure 10 that stores a nozzle 12, a charged electrode 13 and a deflection electrode 15 therein and partitions a scattering space Sa of ink particles; a discharge surface 50a in which an ink discharge port 50b through which ink particles deflected by the deflection electrode 15 are discharged to the outside and an air discharge port 50c through which air is discharged to the outside are opened respectively; and an air discharge member 50 that partitions an air supply passage S3 separated from the scattering space Sa and supplies air to the air discharge port 50c through the air supply passage S3.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] The technology disclosed herein relates to an inkjet recording apparatus. [Background technology]

[0002] 2. Description of the Related Art Conventionally, inkjet recording devices for performing printing processing on a workpiece have been known.

[0003] For example, Patent Document 1 discloses an inkjet recording device that includes a nozzle (nozzle head) that ejects ink particles (droplets), a charging electrode that charges the ink particles ejected from the nozzle, and a deflection electrode that deflects the flight direction of the ink particles charged by the charging electrode.

[0004] The inkjet recording device disclosed in Patent Document 1 can achieve a desired printing process by landing ink droplets on the surface of a workpiece and adjusting the landing position using a deflection electrode.

[0005] Here, the nozzle, charging electrode, and deflection electrode according to Patent Document 1 are housed inside a cover that forms a print head (inkjet head), and this cover defines the space in which ink particles fly.

[0006] In such a configuration, ink particles may bounce off the surface of the workpiece, or may be caused by repulsive forces generated by the workpiece being charged, causing ink particles to return to the print head and soil the inside and outside of the print head.

[0007] Therefore, Patent Document 1 discloses that air is supplied to the ink droplet ejection space defined within the cover by connecting an air supply path for supplying air to the ink droplet ejection space. In this case, air is ejected to the outside through the ink droplet ejection port, thereby preventing the ink droplets from bouncing back. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-74183 Summary of the Invention [Problem to be solved by the invention]

[0009] The inventors of the present application have considered using the air for various purposes by appropriately changing the air supply mode. For example, if the work contains moisture, increasing the air flow rate and ejecting it forcefully makes it possible to dry the work while printing. Also, if the work is cold and has frost on it, increasing the air temperature and ejecting hot air makes it possible to remove the frost while printing.

[0010] However, the inventors of the present application have realized that when air is supplied into the flight space as described in Patent Document 1, the manner in which air is supplied cannot be freely changed.

[0011] That is, if the air flow velocity is too strong, it may disrupt the flow of ink particles, and if the air temperature is too high, it may have a negative effect on the atomization of ink.

[0012] As such, when using known configurations, the air supply mode can only be changed within a range that does not impair the flow of ink particles and the atomization of ink, and air must be supplied under such restrictive conditions.

[0013] The technology disclosed herein has been made in consideration of the above points, and its purpose is to alleviate the constraints imposed on the air discharged to the outside. [Means for solving the problem]

[0014] Specifically, a first aspect of the present disclosure relates to an inkjet recording apparatus that includes a nozzle that ejects ink droplets, a charging electrode that charges the ink droplets ejected from the nozzle, a deflection electrode that deflects the flight direction of the ink droplets charged by the charging electrode, and a housing that houses the nozzle, the charging electrode, and the deflection electrode and defines a flight space for the ink droplets.

[0015] According to a first aspect of the present disclosure, the inkjet recording device includes an ink ejection port that ejects ink droplets deflected by the deflection electrode to the outside, an ejection surface on which air ejection ports are provided around the ink ejection port and that eject air to the outside, and an air supply unit that defines an air supply path separated from the flight space and supplies air to the air ejection port via the air supply path.

[0016] Here, the term "around the ink ejection orifice" is not limited to the area surrounding the ink ejection orifice, but refers to the entire area near the ink ejection orifice.

[0017] The air supply unit may be separate from the housing or may be integrated with the housing.

[0018] According to this configuration, air outlets for discharging air to the outside are opened around the ink outlets for discharging ink droplets to the outside, and air is supplied to these air outlets via an air supply path.

[0019] The air supply path is separated from the ink droplet flight space, so that the air supplied through the air supply path does not interfere with the ink droplets flying within the housing. This makes it possible to change the air supply mode without impairing the flow and atomization of the ink droplets.

[0020] In this way, with the above-described configuration, when air is ejected from the print head, it is possible to ease the constraints imposed on the air.

[0021] According to the second aspect of the present disclosure, the air ejection port may be made up of a plurality of holes, and the plurality of holes may be arranged to surround the ink ejection port.

[0022] This configuration allows the ink ejection ports and the air ejection ports to be located close to each other, which is advantageous in suppressing the rebound of ink particles.

[0023] Furthermore, according to a third aspect of the present disclosure, the air supply unit may have the ejection surface and a back surface facing the ejection surface, and may be configured as a separate member from the housing, and the air supply path may be formed between the back surface and the ejection surface.

[0024] Here, the air supply unit may be configured to be in direct contact with the housing, or may be configured not to be in direct contact with the housing.

[0025] According to this configuration, the air supply unit is configured as a separate member from the housing. For example, by removing the air supply unit depending on whether an air supply path is required, the ease of use of the inkjet recording apparatus I can be improved.

[0026] Furthermore, according to a fourth aspect of the present disclosure, an ink passage hole that allows ink particles deflected by the deflection electrode to pass through may be provided on one end surface of the housing, and the air supply unit may be attached to the one end surface of the housing so that the ink passage hole and the ink ejection port are connected.

[0027] According to this configuration, the air supply unit is attached to one end surface of the housing, which is advantageous in terms of stably holding the air supply unit.

[0028] Furthermore, according to a fifth aspect of the present disclosure, the flight space may be composed of an internal space of the housing and an ink ejection path provided in the air supply section and supplying ink droplets to the ink ejection port, and the ink passage hole and the ink ejection port may be connected via the ink ejection path.

[0029] According to this configuration, when the air discharge member is attached to the housing, the housing and the air discharge member can form a space for ink droplets to fly.

[0030] According to a sixth aspect of the present disclosure, an air supply pipe communicating with the air supply path may be provided inside the housing.

[0031] According to this configuration, by providing the air supply pipe inside the housing, the ink jet recording apparatus can be made more compact.

[0032] Furthermore, according to a seventh aspect of the present disclosure, the inkjet recording device may include a print head having the nozzles, the charging electrode, the deflection electrode, and the housing, and ejecting ink in the form of ink droplets, and a controller connected to the print head and supplying ink to the nozzles, and the controller may include an ink tank that stores the ink to be supplied to the nozzles, and an air pump that injects air into the air supply path.

[0033] According to this configuration, air can be supplied from a controller connected to the ink head.

[0034] According to an eighth aspect of the present disclosure, the air pump may inject air into both the air supply path and the flight space.

[0035] According to this configuration, it is possible to eject air from the ink jetting space through the ink ejection port while ejecting air from the air supply path through the air ejection port. [Effects of the Invention]

[0036] As described above, according to the inkjet recording apparatus, when air is ejected to suppress contamination, it is possible to ease the constraints imposed on the air. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a diagram illustrating an example of the overall configuration of an automatic printing system. [Figure 2A] FIG. 2A is a diagram illustrating a schematic configuration of an inkjet recording apparatus. [Figure 2B] FIG. 2B is a diagram illustrating a schematic configuration of a print head. [Figure 3] FIG. 3 is a perspective view illustrating the overall configuration of a print head. [Figure 4] FIG. 4 is a perspective view illustrating the tip of the print head. [Figure 5] FIG. 5 is an exploded perspective view illustrating the tip of the print head. [Figure 6] FIG. 6 is an exploded perspective view illustrating the tip of the print head. [Figure 7A] FIG. 7A is a cross-sectional view that schematically illustrates one cross section of a print head. [Figure 7B] FIG. 7B is a cross-sectional view that schematically illustrates another cross section of the print head. [Figure 8] FIG. 8 is a cross-sectional view partially illustrating one cross section of a print head. [Figure 9A] FIG. 9A is a perspective view partially illustrating one cross section of a print head. [Figure 9B] FIG. 9B is a perspective view partially illustrating another cross section of the print head. [Figure 10] FIG. 10 is a flowchart illustrating a process related to air purging. [Figure 11] FIG. 11 is a perspective view illustrating a modified example of the print head. [Figure 12] FIG. 12 is a diagram illustrating a cross section of a modified print head. [Figure 13] FIG. 13 is a diagram illustrating another cross section of a modified print head. DETAILED DESCRIPTION OF THE INVENTION

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the following description is for illustrative purposes only.

[0039] That is, in this specification, an industrial inkjet printer will be described as an example of an inkjet recording device, but the technology disclosed herein can be applied to general equipment that uses inkjet, regardless of whether it is called an inkjet recording device or an industrial inkjet printer.

[0040] Furthermore, in this specification, printing processing using an inkjet recording device will be described, but the term "printing processing" as used here includes all processing using inkjet technology, such as printing characters and marking figures.

[0041] <Overall structure> FIG. 1 is a diagram illustrating the overall configuration of an automatic printing system S. FIG. 2A is a diagram illustrating the schematic configuration of an inkjet recording device I, and FIG. 2B is a diagram illustrating the schematic configuration of a print head 1 in the inkjet recording device I. The automatic printing system S illustrated in FIG. 1 is installed on a conveyor line L in a factory or the like, and is configured to perform printing processing in order on each workpiece W flowing along the conveyor line L. Note that the application of this disclosure is not limited to the automatic printing system S. It can also be applied to printing systems that use methods other than automatic.

[0042] Specifically, the automatic printing system S includes an inkjet recording device I that performs printing by causing particulate ink (ink particles) to land on a workpiece W, and an operation terminal 800 and an external device 900 that are connected to the inkjet recording device I. Note that the operation terminal 800 and the external device 900 are not essential.

[0043] More specifically, the inkjet recording device I illustrated in Figures 1 to 2B includes a print head 1 that ejects ink droplets from a nozzle 12 and causes the ink droplets to land on a workpiece W, and a controller 100 that supplies control signals, ink, and solvent to the print head 1. The controller 100 supplies a control signal to the print head 1, thereby controlling the trajectory of the ink droplets. This adjusts the landing positions of the ink droplets on the workpiece W, allowing the desired printing process to be achieved.

[0044] In particular, the inkjet recording apparatus I according to this embodiment is configured as a so-called continuous ink jet printer (CIJ). That is, in the inkjet recording apparatus I, ink is constantly circulating inside the apparatus even when no printing process is being performed in order to prevent clogging (particularly clogging of the nozzles 12) caused by ink volatilization. By adopting the continuous method, it is possible to use quick-drying ink without causing clogging.

[0045] Furthermore, the inkjet recording apparatus I according to this embodiment is capable of cleaning each part of the print head 1, such as the nozzles 12, by sending a solvent to the print head 1. The solvent used for cleaning can be recovered as needed and reused to adjust the concentration (viscosity) of the ink.

[0046] To achieve the circulation of ink and solvent, the print head 1 is equipped with nozzles 12 that eject ink or solvent, as well as a gutter 16 that collects the ink or solvent ejected from the nozzles 12. The ink or solvent sent from the controller 100 to the print head 1 is ejected from the nozzles 12 and collected by the gutter 16. The collected ink or solvent is sent back to the controller 100 and reused. By repeating this process, the ink and solvent can be circulated.

[0047] Additionally, the inkjet recording apparatus I according to this embodiment has a function for ejecting air from its print head 1. In the following description, this function and the associated processing will be referred to as "air purging." By performing air purging during printing, the inkjet recording apparatus I can prevent contamination of the print head 1, dry the workpiece W, and defrost the workpiece W.

[0048] The operation terminal 800 has, for example, a central processing unit (CPU) and a storage device, and is connected to the controller 100. The operation terminal 800 sets printing conditions for printing and functions as a terminal for displaying information related to the printing to the user.

[0049] The printing conditions in this embodiment include the content of the character string to be printed, as well as the conditions and parameters related to the air purge described above (hereinafter also referred to as "purge settings").

[0050] The printing conditions set by the operation terminal 800 are output to the controller 100 and stored in its memory unit 102. In addition to or instead of the memory unit 102 of the controller 100, the operation terminal 800 may store the printing conditions.

[0051] The operation terminal 800 can be integrated into the controller 100, for example. In this case, the term "operation terminal" is not used, but rather a term such as "control unit" is used. However, at least in this embodiment, the operation terminal 800 and the controller 100 are separate entities.

[0052] The external device 900 is connected to the controller 100 as needed. In the example shown in Figures 1 and 2A, the external device 900 includes a workpiece detection sensor 901, a conveying speed sensor 902, and a programmable logic controller (PLC) 903.

[0053] Specifically, the workpiece detection sensor 901 detects the presence or absence of the workpiece W on the conveying line L, and outputs a signal (detection signal) indicating the detection result to the controller 100. The detection signal output from the workpiece detection sensor 901 functions as a trigger (printing trigger) for starting the printing process.

[0054] The conveying speed sensor 902 is composed of, for example, a rotary encoder, and is capable of detecting the conveying speed of the workpiece W. The conveying speed sensor 902 outputs a signal (detection signal) indicating the detection result to the controller 100. The controller 100 controls the timing of ejecting ink droplets from the print head 1 based on the detection signal input from the conveying speed sensor 902.

[0055] 2A, the PLC 903 is electrically connected to the controller 100. The PLC 903 is used to control the automatic printing system S according to a predetermined sequence.

[0056] In addition to the devices and equipment described above, the inkjet recording apparatus I can also be connected to devices for operation and control, computers for performing various other processes, storage devices, peripheral devices, etc. In this case, the connection may be, for example, a serial connection such as IEEE1394, RS-232, RS-422, or USB, or a parallel connection. Alternatively, electrical, magnetic, or optical connection via a network such as 10BASE-T, 100BASE-TX, or 1000BASE-T may be employed. In addition to wired connections, wireless connections using wireless LANs such as IEEE802, or radio waves, infrared rays, or optical communications such as Bluetooth (registered trademark) may also be employed. Furthermore, storage media used in storage devices for exchanging data and saving various settings may include, for example, various memory cards, magnetic disks, magneto-optical disks, semiconductor memories, and hard disks.

[0057] The hardware configuration of the controller 100 and the print head 1, and the configuration related to the control of the print head 1 by the controller 100 will be explained below in order.

[0058] <Controller 100> The controller 100 electrically controls the print head 1 and can supply ink for printing, a solvent for diluting the ink, and air for spraying onto the surface of the workpiece W to the print head 1.

[0059] Specifically, the controller 100 according to this embodiment includes, as components related to electrical control, a memory unit 102 that stores the aforementioned printing conditions, a control unit 101 that controls each part of the controller 100 and the print head 1, and an operation display unit 103 that accepts operations by the user and displays information to the user.

[0060] The controller 100 also includes components related to the supply of ink, etc., such as an ink supply unit 104 that supplies ink to the nozzles 12 of the print head 1, a solvent supply unit 105 that supplies solvent to the nozzles 12 and the ink supply unit 104, and an air pump 106 that supplies air to the print head 1 to perform the aforementioned air purge.

[0061] (Storage unit 102) The memory unit 102 is configured to store printing conditions set via the operation display unit 103 described below or the operation terminal 800, and to output the stored printing conditions to the control unit 101 based on a control signal from outside.

[0062] Specifically, the storage unit 102 is configured using a volatile memory, a non-volatile memory, a hard disk drive (HDD), a solid state drive (SSD), etc., and can temporarily or continuously store information indicating printing conditions. Note that, when the operation terminal 800 is incorporated into the controller 100, the operation terminal 800 may also serve as the storage unit 102.

[0063] (Control unit 101) Based on the printing conditions stored in the memory unit 102, the control unit 101 controls at least the ink supply unit 104, solvent supply unit 105, and air pump 106 in the controller 100, and the nozzle 12, charging electrode 13, and deflection electrode 15 in the print head 1. The control unit 101 controls each unit, thereby performing printing processing on the workpiece W.

[0064] Specifically, the control unit 101 has a CPU, memory, and input / output bus, and generates a control signal based on a signal indicating information input via the operation display unit 103 or the operation terminal 800 and a signal indicating the printing conditions read from the storage unit 102. The control unit 101 outputs the generated control signal to the controller 100 and each part of the inkjet recording apparatus I, thereby controlling the printing process on the workpiece W.

[0065] For example, when processing the workpiece W, the control unit 101 reads the print content stored in the memory unit 102 and generates a control signal based on the print content. Then, the control unit 101 outputs the control signal to the charging electrode 13, thereby causing the ink droplets to fly so as to achieve landing positions corresponding to the print content.

[0066] (Operation display section 103) The operation display unit 103 is provided, for example, on a housing constituting the controller 100 (see FIG. 1). This operation display unit 103 is composed of a display that displays various information related to the inkjet recording apparatus I, and a switch consisting of, for example, a plurality of push buttons. By operating the operation display unit 103, it is possible to switch the power of the inkjet recording apparatus I on / off, etc. Note that when an operation terminal 800 is incorporated into the controller 100, the operation terminal 800 may also serve as the operation display unit 103.

[0067] This operation display unit 103 can set printing conditions for printing, similar to the above-mentioned operation terminal 800. The printing conditions set by the operation display unit 103 are output to the controller 100 and stored in its memory unit 102. In the following description, it is assumed that the user operates the operation display unit 103, but the operation terminal 800 can also be used instead of the operation display unit 103.

[0068] (ink supply unit 104) The ink supply unit 104 has, as its main components, an ink cartridge 104a that contains refill ink, and a main tank 104b to which ink is supplied from the ink cartridge 104a. The ink cartridge 104a, main tank 104b, and print head 1 are fluidly connected via an ink distribution path 104c.

[0069] Of these, the ink cartridge 104a is configured to be detachable from the controller 100, and by replacing it, the main tank 104b can be replenished with ink.

[0070] In this way, the inkjet recording apparatus I according to this embodiment is configured as a so-called "cartridge-type" inkjet printer, but is not limited to this configuration. For example, it may be configured to have a tank that can be opened and closed manually, and to replenish the tank with ink.

[0071] The main tank 104b is configured to store ink whose concentration (viscosity) is adjusted by a solvent. To achieve this configuration, a solvent path is connected to the path from the ink cartridge 104a to the main tank 104b. The main tank 104b according to this embodiment is a container that stores ink liquid to be supplied to the nozzles 12, and is an example of an "ink tank."

[0072] The ink circulation path 104c is a path for supplying ink to the print head 1 and includes, for example, a path for sending ink to the nozzles 12 and a path for returning ink from the gutter 16. The former path connects the ink cartridge 104a, the main tank 104b, and the nozzles 12. The latter path connects the gutter 16 and the main tank 104b. These paths allow ink to circulate between the print head 1 and the controller 100.

[0073] Although not shown, the ink flow path 104c is provided with, for example, a plurality of electromagnetic valves and a plurality of pumps. Of these, each electromagnetic valve opens and closes in response to a control signal output from the control unit 101, thereby controlling the flow of ink. Meanwhile, each pump receives a control signal output from the control unit 101 to pump ink, and can control the flow of ink in the same way as the electromagnetic valves.

[0074] (Solvent supply unit 105) The solvent supply unit 105 has, as its main components, a solvent cartridge 105a that contains replenishment solvent and a conditioning tank 105b that stores the solvent used for cleaning. The solvent cartridge 105a, conditioning tank 105b, and print head 1 are fluidly connected via a solvent flow path 105c.

[0075] Of these, the solvent cartridge 105a is configured to be detachable from the controller 100. By replacing the solvent cartridge 105a, it is possible to replenish the solvent in the controller 100. A solvent tank may be provided instead of the solvent cartridge 105a.

[0076] The conditioning tank 105b is configured to store the solvent used for cleaning. As described above, the solvent ejected from the nozzles 12 is collected by the gutter 16, just like the ink. Therefore, the path for returning the ink from the gutter 16 also serves as the path for returning the solvent. This path branches off midway, and one of the branches is connected to the main tank 104b described above. The other of the branches is connected to the conditioning tank 105b.

[0077] The solvent flow path 105c is a path for supplying solvent to the print head 1, main tank 104b, etc., and includes, for example, a path for sending solvent to the nozzles 12 and a path for returning solvent from the gutter 16. The former path connects the solvent cartridge 105a and the nozzles 12. As mentioned above, the latter path also serves as a path for returning ink. These paths allow the solvent to circulate between the print head 1 and the controller 100.

[0078] Although not shown, the solvent flow path 105c is provided with, for example, a plurality of solenoid valves and a plurality of pumps. Of these, each solenoid valve receives a control signal output from the control unit 101 to open and close, thereby controlling the flow of the solvent. Meanwhile, each pump receives a control signal output from the control unit 101 to pump the solvent, and can control the flow of the solvent in the same way as the solenoid valves.

[0079] The classification of the solvent flow path 105c and the ink flow path 104c described above is merely a convenient classification made for the sake of simplicity of explanation. The solvent flow path 105c and the ink flow path 104c are essentially inseparable because they are connected to each other or one serves as the other.

[0080] (Air Pump 106) The air pump 106 is configured to pump air upon receiving a control signal from the control unit 101. The air pumped by the air pump 106 is supplied to the print head 1 through an air tube 106c and used for air purging.

[0081] The air tube 106c according to this embodiment is branched midway, one of which is connected to the ink space S1 as the internal space of the housing 10, and the other of which is connected to an air supply pipe 19 (see FIG. 2B) described below. As described below, the housing 10 is a member for accommodating the nozzle 12 and the like therein.

[0082] The phrase "communicating with the ink space S1 in the housing 10" can be interpreted in a broad sense. That is, as shown in Fig. 2A, the ink space S1 may be directly communicated with the ink space S1, or the ink space S1 may be indirectly communicated with the ink space S1 via another path such as the solvent flow path 105c.

[0083] 2A illustrates the air pump 106 as one element of the controller 100, but the present invention is not limited to this configuration. The air pump 106 may be built into the controller 100, or may be provided as an external device independent of the controller 100. Furthermore, the air pump 106 is not essential. For example, so-called factory air can be used by connecting air equipment installed in a factory or the like to the air tube 106c.

[0084] Furthermore, a branched air tube 106c is not essential. For example, an air tube leading to the ink space S1 and an air tube connected to the air supply pipe 19 may be provided separately. In this case, a dedicated air pump may be connected to each air tube. Alternatively, an air pump may be connected to one air tube, and factory air may be supplied to the other air tube.

[0085] (Other components) The controller 100 is provided with a connection cable 107, which is a bundle of covered electrical wiring for sending and receiving control signals, tubes for sending and receiving ink (specifically, tubes defining ink flow path 104c), tubes for sending and receiving solvent (specifically, tubes defining solvent flow path 105c), and air tube 106c for supplying air. This connection cable 107 is flexible and is connected to the upper end of the print head 1 (see Figures 1 and 3). The controller 100 and print head 1 are electrically and fluidly connected via this connection cable 107.

[0086] <Print head 1> The print head 1 ejects ink of adjusted concentration as ink droplets based on the control signal, ink, and solvent supplied from the controller 100. The print head 1 deflects the flight direction of the ejected ink droplets and causes the deflected ink droplets to land on the surface of the workpiece W, thereby performing printing on the workpiece W.

[0087] Specifically, the print head 1 of this embodiment comprises, as its main components, a vibrator 11 that vibrates the ink, a nozzle 12 that ejects the ink or solvent vibrated by the vibrator 11, a charging electrode 13 that charges the particulate ink ejected from the nozzle 12, a charge detection sensor 14 that monitors the charged state of the ink, a deflection electrode 15 that deflects the flight direction of the ink charged by the charging electrode 13, and a gutter 16 that collects the ink that has been undeflected by the deflection electrode 15 or the solvent that has passed through the nozzle 12 (specifically, the solvent ejected from the nozzle 12).

[0088] 2B, the print head 1 includes a housing 10 that houses a vibrator 11, a nozzle 12, a charging electrode 13, a charge detection sensor 14, a deflection electrode 15, and a gutter 16, and defines an ink droplet flight space Sa. The print head 1 is capable of ejecting ink droplets deflected by the deflection electrode 15 to the outside of the housing 10 through the flight space Sa.

[0089] The ink droplet flight space Sa is partitioned by an ink space S1 provided within the housing 10 and an ink discharge path S2 provided in the air discharge member 50 (described later). The vibrator 11, nozzle 12, charging electrode 13, charge detection sensor 14, and deflection electrode 15 described above are laid out in the former ink space S1.

[0090] Below, each part of the print head 1 will be explained in order. In the following description, the "upper-lower direction" refers to the direction along the vertical direction. For example, the upper side of the paper in FIG. 2B corresponds to the "upper direction," and the lower side of the paper in the same figure corresponds to the "lower direction." In other figures, the corresponding direction will also be called the "upper-lower direction."

[0091] (Vibrator 11) As shown in FIG. 2B, the vibrator 11 is disposed near the upper end of the ink space S1. The vibrator 11 according to this embodiment has a built-in device (e.g., a piezoelectric element) for applying vertical vibrations to the ink. The vibrator 11 is configured so that ink is supplied to it via a connection cable 107, and is capable of vibrating the ink thus supplied. The ink vibrated by the vibrator 11 is supplied to the nozzle 12.

[0092] Although not shown in the drawings, the vibrator 11 according to this embodiment is grounded.

[0093] (Nozzle 12) As shown in FIG. 2B, the nozzle 12 is connected to the lower end of the vibrator 11 and is positioned with its open end (ink ejection port) facing downward. Ink vibrated by the vibrator 11 can be ejected from the open end of the nozzle 12. A return path (not shown) is connected to the nozzle 12 to release pressure inside the print head 1, for example, during shutdown. In addition, the solvent can be expelled from the nozzle 12 through a suction path (not shown).

[0094] Here, ink ejected from the nozzle 12 without being vibrated by the vibrator 11 flows as a shaft-shaped so-called "ink shaft." On the other hand, vibrated ink is atomized immediately after being ejected from the nozzle 12, becoming so-called "ink particles." The ink ejected from the nozzle 12 passes through the charging electrode 13.

[0095] The solvent supplied to clean the print head 1 passes through the vibrator 11 and the nozzle 12 in that order, and is then ejected from the nozzle 12. The ejected solvent flows axially and passes through the charging electrode 13.

[0096] (Charged electrode 13) 2B, the charging electrode 13 is composed of a pair of left and right metal plates, and is disposed below the nozzle 12. The pair of metal plates are fixed in position so that their longitudinal directions are aligned along the up-down direction and so that they face each other. Ink ejected from the nozzle 12 passes between the pair of metal plates.

[0097] A potential (positive potential) is applied to the charging electrode 13 according to this embodiment at least when a printing operation is performed. This generates a potential difference between the vibrator 11 and the charging electrode 13, making it possible to charge ink droplets passing through the charging electrode 13. In order to charge each ink droplet, the charging electrode 13 according to this embodiment is disposed near a breakpoint where the ink ejected from the nozzle 12 breaks into particles.

[0098] More specifically, a pulse potential that can be controlled by the controller 100 is applied to the charging electrode 13. When a relatively high voltage is applied to the charging electrode 13, the amount of charge (magnitude of negative charge) of each ink droplet becomes larger compared to when a lower voltage is applied. When each ink droplet has a large charge, it is deflected more by the deflection electrode 15 compared to when the charge is small. The controller 100 can control the amount of deflection of the ink droplet by adjusting the magnitude of the pulse potential. The ink droplet charged by the charging electrode 13 passes beside the charge detection sensor 14 and reaches the deflection electrode 15.

[0099] Furthermore, the solvent discharged from the nozzle 12 passes beside the charge detection sensor 14 and reaches the deflection electrode 15 without being charged.

[0100] (Charge detection sensor 14) As shown in Fig. 2B, the charge detection sensor 14 is disposed below the charging electrode 13. More specifically, the charge detection sensor 14 is laid out directly below the metal plate that constitutes the charging electrode 13 (in the example shown in Fig. 2B, the metal plate on the right side of the page), and is disposed so as not to intersect with the trajectory of the flying ink particles. By adopting such an arrangement, it is possible to avoid collisions between the ink particles and the charge detection sensor 14.

[0101] Furthermore, the charge detection sensor 14 according to this embodiment is connected to a circuit board 17 (see FIG. 7A) provided inside the housing 10. The charge detection sensor 14 can detect the charge state of ink particles passing by its side. The detection result by the charge detection sensor 14 is output to the control unit 101 as a detection signal. Based on this detection signal, the control unit 101 can determine whether each ink particle is appropriately charged.

[0102] (Deflection electrode 15) 2B, the deflection electrode 15 is composed of a pair of left and right metal plates (so-called "opposing electrodes") and is disposed below the charging electrode 13 and the charge detection sensor 14. The pair of metal plates are fixed in a position in which their respective longitudinal directions are aligned substantially vertically and facing each other. Ink particles that have passed through the charging electrode 13 pass between the pair of metal plates that make up the deflection electrode 15.

[0103] A voltage that can be controlled by the controller 100 is applied to the deflection electrodes 15. This generates a potential difference between the metal plates that make up the deflection electrodes 15. This potential difference can deflect the flight direction of the ink droplets. The flight direction of the ink droplets can be deflected along the direction in which the pair of metal plates are aligned.

[0104] That is, the trajectory of the ink droplets can be controlled via the voltages applied to the charging electrode 13 and the deflection electrode 15, respectively. The ink droplets controlled in this way include those deflected by the deflection electrode 15 and those not deflected. Of these, the former ink droplets are involved in printing on the workpiece W. These ink droplets are ejected from the ejection port 10b provided on the bottom surface of the housing 10 and land on the workpiece W.

[0105] On the other hand, ink particles that are not deflected by the deflection electrode 15 do not participate in printing on the workpiece W. These ink particles, or axial ink that has not been atomized in the first place, reach the gutter 16, as shown by the dashed line in Figure 2B. Similarly, the solvent used to clean the nozzles 12, etc. of the print head 1 and that has passed through the deflection electrode 15 also reaches the gutter 16.

[0106] (Gutter 16) 2B, the gutter 16 is configured as a curved pipe with its open end facing upward, and is disposed below the deflection electrode 15. The gutter 16 according to this embodiment can collect ink that is not involved in printing on the workpiece W and the solvent that has passed through the nozzle 12 (specifically, the solvent that has been ejected from the nozzle 12).

[0107] More specifically, in this embodiment, the open end of the gutter 16 and the open end of the nozzle 12 are arranged to face each other. By arranging them in this manner, it becomes possible for the liquid that flows vertically from the open end of the nozzle 12 to be received by the open end of the gutter 16.

[0108] The ink or solvent collected by the gutter 16 is returned to the controller 100 via the ink flow path 104c, the solvent flow path 105c, etc., and is stored in the main tank 104b or the conditioning tank 105b.

[0109] (Main operation of print head 1) As explained above, when printing is performed on the workpiece W, ink vibrated by the vibrator 11 is ejected from the nozzle 12. This ink is supplied as needed from the ink supply unit 104 of the controller 100. The ink ejected from the nozzle 12 breaks down into particles immediately after ejection and is charged by the charging electrode 13. The ink particles charged by the charging electrode 13 have their charged state detected by the charge detection sensor 14, and then pass through the deflection electrode 15.

[0110] The ink droplets, whose flight direction has been deflected by the deflection electrode 15, then pass through the ink space S1 serving as the flight space Sa and the ink ejection path S2 in that order, and are ejected to the outside of the print head 1 (see arrow F1 in Figures 2B, 9A, and 9B). The ink droplets ejected from the print head 1 land on the surface of the workpiece W. Here, the landing position of the ink droplets is controlled by the charge amount of each ink droplet and the voltage applied to the deflection electrode 15.

[0111] As described above, the inkjet recording apparatus I according to this embodiment is configured as a continuous-type inkjet printer, so that ink continues to be ejected from the nozzles 12 even when no printing process is being performed. The ink ejected at this time is not deflected by the deflection electrodes 15 (in other words, it is "non-deflected"). The non-deflected ink does not participate in the printing process, but is collected by the gutter 16, circulated within the apparatus, and reused.

[0112] Furthermore, when cleaning the print head 1, a solvent is ejected from the nozzle 12. This solvent is supplied as needed from a solvent supply unit 105 of the controller 100. The solvent ejected from the nozzle 12 is collected by the gutter 16 and reused without being particulated, charged, deflected, or the like.

[0113] When printing is performed on the workpiece W, air is ejected by the air pump 106 (air purge) in addition to ink being ejected from the nozzle 12. As described above, the air tube 106c for supplying air is branched into one end communicating with the ink space S1 inside the housing 10 and the other end connected to the air supply pipe 19.

[0114] This air tube 106c is used to eject air from the print head 1. As described above, one of the branches can be used to dry the inside of the ink space S1 with air, or to eject air through this ink space S1 and, ultimately, through the ink particle flight space Sa (see arrow F2 in FIG. 2B).

[0115] On the other hand, the other branched portion as described above can discharge air via air supply pipe 19 and air supply path S3. Specifically, a solenoid valve 18 is housed near the connection between air tube 106c and air supply pipe 19. Solenoid valve 18 according to this embodiment is electrically connected to control unit 101, and opens and closes in response to a control signal output from control unit 101. By appropriately opening and closing solenoid valve 18, it is possible to control the flow of air in air supply pipe 19 and send air into air supply path S3.

[0116] 2B and other examples, the air supply path S3 is separated from the ink droplet flight space Sa. Therefore, the air discharged to the outside via the air supply path S3 is discharged from the print head 1 without affecting the atomization and flow of the ink droplets (see arrow F3 in FIGS. 2B and 8).

[0117] Here, the air supply path S3 according to this embodiment is defined by an air discharge member 50 serving as an air supply unit. In the following, to provide a detailed description of this air discharge member 50, the configuration related to this member will be described in order.

[0118] <Air discharge member 50> Figure 3 is a perspective view illustrating the overall configuration of print head 1, and Figure 4 is a perspective view illustrating the tip of print head 1. Figures 5 and 6 are exploded perspective views illustrating the tip of print head 1, and Figures 7A and 7B are cross-sectional views each schematically illustrating one cross section and another cross section of print head 1.

[0119] 8 is a cross-sectional view partially illustrating one cross section of the print head 1, FIG. 9A is a perspective view partially illustrating one cross section of the print head 1, and FIG. 9B is a perspective view partially illustrating another cross section of the print head 1.

[0120] Here, "one cross section of the print head 1" refers to a cross section that cuts through the air supply pipe 19, as exemplified in Figure 7A, etc. Additionally, "another cross section of the print head 1" refers to a cross section that cuts through the ink ejection path S2, as exemplified in Figure 7B, etc.

[0121] As shown in Fig. 3, the housing 10 has a generally rectangular parallelepiped shape extending in the vertical direction of the page. In the following description, the longitudinal direction of the housing 10 will be simply referred to as the "vertical direction," while the two directions perpendicular to this vertical direction will be referred to as the "front-rear direction" and the "left-right direction," respectively. In other figures, the corresponding directions will also be referred to as the "vertical direction," "front-rear direction," and "left-right direction," respectively.

[0122] Here, "top" refers to the top side of the page in Figure 3, and "bottom" refers to the bottom side of the page. Similarly, "front" refers to the front side of the page in Figure 3 (specifically, the front left side), "back" refers to the back side of the page (specifically, the back right side), "left" refers to the left side of the page (specifically, the lower left side), and "right" refers to the right side of the page (specifically, the upper right side). In other figures, the corresponding terms are referred to as "top," "bottom," "front," "back," "left," and "right," respectively.

[0123] 7A and other figures, the internal space of the housing 10 is divided into an ink space S1 that houses the nozzles 12, charging electrode 13, deflection electrode 15, etc., and a circuit space S4 that houses electronic components such as a circuit board 17. Specifically, a partition plate 10d extending in the left-right and up-down directions is provided inside the housing 10. The space in front of this partition plate 10d constitutes the ink space S1, and the space behind the partition plate 10d constitutes the circuit space S4.

[0124] As described above, arranged in the ink space S1 from above are, in this order, the vibrator 11, the nozzle 12, the charging electrode 13, the charge detection sensor 14, the deflection electrode 15, and the gutter 16. Of these, the charge detection sensor 14 extends from the circuit board 17 arranged in the circuit space S4, and passes through the partition plate 10d to be exposed in the ink space S1.

[0125] Additionally, in the circuit space S4, a circuit board 17 and an air supply pipe 19 are arranged in this order from the front. The circuit board 17 has a thin plate-like outer shape and is fixed in a position that aligns with the partition plate 10d. A charge detection sensor 14 is connected to the front surface of the circuit board 17. The detection result by the charge detection sensor 14 is transmitted to the control unit 101 via this circuit board 17.

[0126] The air supply pipe 19 is connected to an air tube 106c that constitutes the connection cable 107, and extends vertically along the rear surface of the housing 10. The air tube 106c is connected to the upper end of the air supply pipe 19, allowing air to be sent downward. The lower end of the air supply pipe 19 is connected to an air passage hole 10c that opens in the lower surface 10a of the housing 10. This air passage hole 10c allows the air supplied through the air supply pipe 19 to be discharged from the housing 10.

[0127] The air supply pipe 19 and the air tube 106c may be integrated. In this case, the air tube 106c functions as the air supply pipe 19.

[0128] Meanwhile, as shown in Figure 3, a removable cover member 10f is provided on the front surface of the housing 10. The cover member 10f, together with other members, defines the ink space S1. This cover member 10f is designed to be removed, for example, when performing maintenance (particularly manual maintenance) on the nozzles 12, etc. By removing the cover member 10f, the ink space S1 becomes accessible from the outside.

[0129] 3, one end of the connection cable 107 is connected to the upper end of the print head 1. The lower surface of the print head 1 functions as an ejection surface 50a for ejecting ink and air.

[0130] As illustrated in Figures 2B, 3 and 4, the ejection surface 50a is provided with an ink ejection port 50b that ejects ink droplets deflected by the deflection electrode 15 to the outside, and an air ejection port 50c that is provided around the ink ejection port 50b and ejects air to the outside.

[0131] Of these, the ink ejection orifice 50b is formed as an oval opening extending in the left-right direction. The longitudinal direction (i.e., the left-right direction) of the ink ejection orifice 50b is approximately the same as the direction in which the metal plates constituting the deflection electrode 15 are aligned. In other words, the ink ejection orifice 50b extends in the direction in which the ink droplets are deflected.

[0132] 7B, the ink ejection opening 50b is disposed directly below the ink space S1. That is, as shown in FIGS. 4 and 5, the ink ejection opening 50b is disposed on the front side in the front-to-rear direction.

[0133] On the other hand, the air outlet 50c is made up of a plurality of holes (particularly through holes) with the same diameter. As can be seen from Figure 4, the plurality of holes are arranged at equal intervals so as to surround at least the ink outlet 50b.

[0134] In particular, the air ejection ports 50c according to this embodiment are open over the entire ejection surface 50a, excluding the area where the ink ejection ports 50b are open and the area where the bolt holes 52 are provided.

[0135] 8, 9A, and 9B, the holes constituting air outlet 50c extend perpendicularly through outlet surface 50a. This configuration allows the flow of air ejected from air outlet 50c to be directed directly downward (see also arrow F3 in FIG. 2B).

[0136] Here, the ejection surface 50a according to this embodiment is constituted by an air ejection member 50 that is separate from the housing 10 that houses the nozzles 12, circuit board 17, etc. This air ejection member 50 defines an air supply path S3 that is separate from the ink droplet flight space Sa, and is configured to supply air to an air ejection port 50c via this air supply path S3. Air can be ejected to the outside of the print head 1 through this air ejection port 50c. The air ejection member 50 is an example of an "air supply unit."

[0137] Specifically, the air discharge member 50 is a hollow member having a rectangular, thin plate-like outer shape, and has the aforementioned discharge surface 50a and an opposing back surface 50d. As illustrated in Figures 4 and 5, the front-to-rear dimensions of the discharge surface 50a and the back surface 50d each roughly match the front-to-rear dimension of the bottom surface 10a of the housing 10. Similarly, the left-to-right dimensions of the discharge surface 50a and the back surface 50d each roughly match the left-to-right dimension of the bottom surface 10a of the housing 10.

[0138] An air inlet port 50f, to which an air supply pipe 19 can be connected, opens on the back surface 50d of the air discharge member 50. An air supply path S3 is defined inside the air discharge member 50. More specifically, the air supply path S3 according to this embodiment is formed between the back surface 50d and the discharge surface 50a of the air discharge member 50, and connects the air inlet port 50f and the air discharge port 50c.

[0139] 6 and 7A, the air inlet 50f is disposed directly below the circuit space S4. That is, as shown in FIG. 6, the air inlet 50f is disposed on the rear side in the front-to-rear direction (more specifically, behind the ink inlet 50e and the bolt hole 52).

[0140] Similarly, an ink inlet port 50e that connects the ink space S1 to the ink discharge path S2 is opened on the rear surface 50d of the air discharge member 50. The ink discharge path S2 is separated from the air supply path S3 and is defined inside the air discharge member 50. More specifically, the ink discharge path S2 according to this embodiment is formed between the rear surface 50d and the discharge surface 50a of the air discharge member 50, and connects the ink inlet port 50e to the ink discharge orifice 50b.

[0141] As illustrated schematically in FIG. 2B, the air supply path S3 is not connected to the ink space S1 and the ink ejection path S2, which form the flight space Sa, and the two are separated from each other (see also FIG. 9B, etc.).

[0142] The air discharge member 50 also has bolt holes 52, 52 that penetrate the member in the thickness direction. Each bolt hole 52 is configured as a pair of through holes aligned in the left-right direction, and opens to the discharge surface 50a and back surface 50d of the air discharge member 50. As shown in Figures 6 and 9B, each bolt hole 52 is located on the rear side in the front-to-rear direction (in this embodiment, behind the ink inlet port 50e and ink discharge port 50b, and in front of the air inlet port 50f).

[0143] By arranging them in this manner, the bolt holes 52 and the ink ejection ports 50b can be spaced apart, which makes it possible to provide more air ejection ports 50c around the ink ejection ports 50b.

[0144] As already explained, the air discharge member 50 according to this embodiment is separate from the housing 10. The air discharge member 50 is configured to be detachable from the housing 10. When the air discharge member 50 is attached, the rear surface 50d of the air discharge member 50 is attached to one end surface of the housing 10 (specifically, the bottom surface 10a of the housing 10). By attaching the air discharge member 50, the discharge surface 50a can be considered to be the bottom surface of the entire print head 1.

[0145] A pair of left and right bolt insertion portions 10e are provided on the bottom surface 10a of the housing 10 to allow the air discharge member 50 to be attached and detached. Each bolt insertion portion 10e is provided as a hole opening in the bottom surface 10a of the housing 10, and is provided at a position corresponding to the aforementioned bolt hole 52. Specifically, each bolt insertion portion 10e is closer to the air passage hole 10c than to the ink passage hole 10b (see FIG. 5). By adopting such a layout, all of the bolt insertion portions 10e according to this embodiment are disposed in the circuit space S4, not in the ink space S1 (see FIG. 7B).

[0146] Therefore, by bringing the underside 10a of the housing 10 and the backside 50d of the air discharge member 50 into contact with each other, one of the bolt holes 52 can be aligned with the corresponding bolt insertion portion 10e. With the air discharge member 50 aligned in this manner, the air discharge member 50 can be attached to the housing 10 by inserting and fastening a bolt 51 into the bolt hole 52 and the bolt insertion portion 10e.

[0147] 2B and other figures, when the air discharge member 50 is attached to the housing 10, the ink space S1 and the ink discharge path S2 are in communication with each other. To achieve this, the lower surface 10a of the housing 10 is provided with ink passing holes 10b that allow ink particles deflected by the deflection electrode 15 to pass through (see also FIG. 5).

[0148] The ink passing hole 10b penetrates the bottom surface 10a of the housing 10 and is formed as an oval through-hole extending in the left-right direction. As illustrated in Fig. 7B and other figures, the ink passing hole 10b communicates with the ink space S1. Like the ink ejection orifice 50b, the ink passing hole 10b extends in the direction in which the ink droplets are deflected.

[0149] The air discharge member 50 according to this embodiment is attached to the underside 10a of the housing 10 so that the ink passing holes 10b and the ink discharge openings 50b are connected. Specifically, by attaching the air discharge member 50 to the underside 10a of the housing 10, the ink passing holes 10b, which communicate with the ink space S1, can be connected to the ink inlet 50e, which communicates with the ink discharge path S2. This connects the ink passing holes 10b to the ink discharge openings 50b, connecting the ink space S1 and the ink discharge path S2. The aforementioned flight space Sa is formed by the ink space S1 and the ink discharge path S2, which are connected in this way. As shown by the arrow F1 in FIGS. 2B, 9A, and 9B, ink that has flown within the housing 10 is discharged from the ink discharge openings 50b.

[0150] 2B and other examples, when the air discharge member 50 is attached to the housing 10, the air supply pipe 19 and the air supply path S3 are connected. To achieve this, the air passage hole 10c described above is opened in the lower surface 10a of the housing 10 (see also FIG. 5). As already explained, the air passage hole 10c is connected to the lower end of the air supply pipe 19.

[0151] The air discharge member 50 according to this embodiment is attached to the underside 10a of the housing 10 so that the air passage holes 10c and the air discharge port 50c are connected. Specifically, by attaching the air discharge member 50 to the underside 10a of the housing 10, the air passage holes 10c, which communicate with the air supply pipe 19, can be connected to the air inlet port 50f, which communicates with the air supply path S3. This connects the air passage holes 10c to the air discharge port 50c, and the air supply pipe 19 and the air supply path S3 communicate with each other. As shown by the arrow F3 in FIGS. 2B and 8, air supplied from the air supply pipe 19 is discharged from the air discharge port 50c.

[0152] By connecting the air supply pipe 19 to the air supply path S3, it becomes possible to perform air purging using this air supply path S3. In this embodiment, the control unit 101 constituting the controller 100 executes air purging via the air pump 106, the solenoid valve 18, etc.

[0153] The timing of executing air purging can be changed as appropriate depending on the type of workpiece W, the machining environment, etc. The timing of executing air purging will be described below with reference to FIG.

[0154] <Air purge timing> FIG. 10 is a flowchart illustrating a process related to air purging.

[0155] First, in step S1, the control unit 101 reads the printing conditions. As described above, the printing conditions read in step S1 include purge settings related to air purging.

[0156] The purge settings include parameters indicating the supply mode of the air discharged through the air supply path S3 (specifically, parameters indicating the target values ​​for the air flow rate and temperature), and conditions indicating the timing of air purge execution.

[0157] Of these, the timing for executing air purging can be selected from at least three options, as exemplified by steps S2, S4, and S6 in FIG.

[0158] That is, in step S2 following step S1, the control unit 101 determines whether or not air purging is to be performed constantly. If the determination is YES, the process proceeds to step S3, where the control unit 101 outputs a control signal to the solenoid valve 18 so as to keep the solenoid valve 18 open at all times. As a result, air is supplied to the air supply path S3 while the solenoid valve 18 is continuously open. The air thus supplied is continuously discharged from the air discharge port 50c. By continuously opening the solenoid valve 18, air can be continuously discharged, and air purging is performed at all times.

[0159] On the other hand, if the determination in step S3 is NO, the process proceeds to step S4, where the control unit 101 determines whether or not to perform air purging for each print trigger. If this determination is YES, the process proceeds to step S5, where the control unit 101 outputs a control signal to the solenoid valve 18 in response to the print trigger. Specifically, when a print trigger is input to the control unit 101, in other words, when the workpiece W is detected by the workpiece detection sensor 901, the control unit 101 opens the solenoid valve 18 to perform air purging.

[0160] If the determination in step S4 is NO, the process proceeds to step S6, where the control unit 101 determines whether or not to execute air purging in synchronization with an external input. If this determination is YES, the process proceeds to step S7, where the control unit 101 outputs a control signal to the solenoid valve 18 in accordance with the external input. Specifically, when a signal is being input from the PLC 903, the control unit 101 opens the solenoid valve 18 to execute air purging, but when the signal from the PLC 903 is discontinued, the control unit 101 opens the solenoid valve 18 to interrupt the air purging. This configuration is effective in saving air and, ultimately, in reducing processing costs.

[0161] If the determination in step S6 is also NO, the process proceeds to step S8. In this case, the control unit 101 returns without executing air purging.

[0162] The air supply state in steps S3, S5, and S7 is controlled based on the purge setting described above. For example, the air flow rate is controlled by the air pump 106 and the solenoid valve 18.

[0163] <Air purging using air supply path S3> According to this embodiment, an air outlet 50c for discharging air to the outside is opened around the ink outlet 50b for discharging ink droplets to the outside. Air is supplied to this air outlet 50c via an air supply path S3.

[0164] 7A and 7B, the air supply path S3 is separated from the ink particle flight space Sa. This prevents the air supplied via the air supply path S3 from interfering with the ink particles flying within the housing 10. This makes it possible to change the air supply mode without impairing the flow and atomization of the ink particles.

[0165] In this way, according to this embodiment, when air is ejected from the print head 1, the constraints imposed on the air can be relaxed.

[0166] 4, the air outlets 50c are arranged to surround the ink outlets 50b. This arrangement allows the ink outlets 50b and the air outlets 50c to be close to each other, which is advantageous in preventing contamination of the print head 1 due to ink droplets bouncing off.

[0167] 5, the bolts 51, bolt holes 52, and bolt insertion portions 10e are all located on one side (the rear side) of the print head 1 when the print head 1 is divided into two halves in a predetermined direction (the front-to-rear direction). On the other hand, the ink passing holes 10b, ink inlet ports 50e, and ink ejection ports 50b are all located on the other side (the front side) of the print head 1 when the print head 1 is divided into two halves in the predetermined direction (the front-to-rear direction).

[0168] This arrangement allows the ink ejection port 50b to be spaced apart from the bolt 51 and bolt hole 52, ensuring sufficient space around the ink ejection port 50b. This allows the air ejection port 50c to be located near the ink ejection port 50b, making it possible to place these openings close to each other. This is even more advantageous in preventing contamination of the print head 1 due to ink droplets bouncing off, etc.

[0169] 5, the air discharge member 50 serving as the air supply unit is configured as a separate air discharge member 50 from the housing 10. For example, by removing the air discharge member 50 depending on whether the air supply path S3 is required, the ease of use of the inkjet recording apparatus I can be improved.

[0170] 5, the air discharge member 50 is attached to the lower surface 10a of the housing 10. This is advantageous in terms of holding the air discharge member 50 stably.

[0171] Furthermore, as shown in FIG. 7A, by providing an air supply pipe 19 inside the housing 10, the inkjet recording apparatus I can be configured more compactly.

[0172] As illustrated in Figures 7A and 7B, the interior of the housing 10 is partitioned into a first internal space (ink space S1) that houses at least the nozzle 12, the charging electrode 13, and the deflection electrode 15, and a second internal space (circuit space S4) that houses at least the circuit board 17, and the air supply pipe 19 is provided in the circuit space S4.

[0173] In this way, by providing the air supply pipe 19 in the circuit space S4 instead of the ink space S1, the effects on the flow and particle formation of ink caused by pulsation occurring in the air supply pipe 19 can be suppressed.

[0174] As shown in FIG. 2B, the air pump 106 according to this embodiment injects air into both the air supply path S3 and the flight space Sa (specifically, the ink space S1).

[0175] This makes it possible to eject air from the air supply path S3 through the air ejection port 50c, while also ejecting air from the flight space Sa through the ink ejection port 50b.

[0176] <Modification of Print Head 1> In the above embodiment, the air supply pipe 19 is arranged inside the housing 10, but the present invention is not limited to this arrangement. For example, the air supply pipe 19 may be arranged outside the housing 10. The latter arrangement will be described with reference to Figs. 11 to 13.

[0177] Specifically, Fig. 11 is a perspective view illustrating a modified example of print head 1, and Fig. 12 is a diagram illustrating one cross section of the modified example of print head 1. Fig. 13 is a diagram illustrating another cross section of the modified example of print head 1.

[0178] In the following description, the modified version of the print head 1 will be simply referred to as the "print head" and will be described with the reference numeral "1'" attached to it. The same applies to the other components.

[0179] 11, an air discharge member 50' according to a modified example is attached to the underside of the housing 10' of the print head 1'. The underside of this air discharge member 50' functions as the discharge surface 50a', similar to the embodiment described above.

[0180] Specifically, as illustrated in Figures 12 and 13, the ejection surface 50a' is provided with an ink ejection port 50b' that ejects ink droplets to the outside, and an air ejection port 50c' that is provided around the ink ejection port 50b' and ejects air to the outside.

[0181] Here, the ink ejection port 50b' is configured in the same manner as in the previous embodiment, and communicates with the ink passage hole 10b' that opens on the bottom surface of the housing 10', as shown in Figure 13. The air ejection port 50c' is also configured in the same manner as in the previous embodiment.

[0182] However, the air supply pipe 19' according to this modified example is arranged outside the housing 10', as illustrated in Figures 11 to 13. Specifically, the air supply pipe 19' according to this modified example extends in the vertical direction along the rear surface of the print head 1'.

[0183] The upper end of the air supply pipe 19' is connected to an air facility in a factory or the like, an air pump, etc., while the lower end of the air supply pipe 19' is connected to a connecting part 53' that protrudes from one side (specifically, the rear side) of the air discharge member 50'. Air can be supplied from the air supply pipe 19' to the air discharge port 50c' via this connecting part 53'.

[0184] <Other embodiments> In the above embodiment, a configuration has been described in which the flow of air is controlled by the opening and closing operation of the solenoid valve 18, but the present invention is not limited to this configuration. For example, the flow of air may be controlled by the pumping operation of the air pump 106, without using the solenoid valve 18. In this case, the solenoid valve 18 is not necessary.

[0185] In the above embodiment, air is injected not only into the air supply path S3 but also into the flight space Sa, but this is not limiting. Injection of air into the flight space Sa may be omitted.

[0186] In the above embodiment, the holes constituting the air outlet 50c extend perpendicularly through the ejection surface 50a. However, this configuration is not limited to this. For example, the holes may extend obliquely relative to the ejection surface 50a so as to be away from the ink flow direction. Furthermore, instead of extending the air outlet 50c obliquely, the ejection surface 50a may be inclined obliquely relative to the bottom surface 10a of the housing 10. Furthermore, the air may be ejected not only obliquely, but also in forward, backward, left, and right directions. A configuration in which air is ejected directly downward may be combined with a configuration in which air is ejected obliquely and in forward, backward, left, and right directions. With this configuration, the air ejected from the air outlet 50c is sprayed at a position away from the landing position of the ink droplets on the workpiece W. Furthermore, ejecting air in forward, backward, left, and right directions can keep dust and other foreign matter away from the workpiece W.

[0187] In the above embodiment, the dimensions of the ejection surface 50a in the front-rear and left-right directions are approximately the same as the dimensions of the bottom surface 10a of the housing 10 in the front-rear and left-right directions, but this configuration is not limiting. For example, the ejection surface 50a may extend along the direction in which the workpieces W flow on the conveying line L. With this configuration, it becomes possible to blow air onto the workpieces W at an earlier timing than the ink particles land on the workpieces W.

[0188] In the above embodiment, the lower surface 10a of the housing 10 and the rear surface 50d of the air discharge member 50 are configured to be in contact with each other, but this configuration is not limiting. For example, the air discharge member 50 can be attached to the housing 10 using a separate attachment while the lower surface 10a of the housing 10 and the rear surface 50d of the air discharge member 50 are spaced apart from each other.

[0189] Furthermore, it is not essential to configure the housing 10 and the air discharge member 50 as separate bodies. For example, by devising an ingenious shape for the lower end of the housing 10, it is possible to provide the air supply path S3 at the lower end. In this case, the lower surface 10a of the housing 10 functions as the discharge surface 50a, and the lower end of the housing 10 functions as an air supply unit. [Explanation of symbols]

[0190] S Automatic Printing System 1 print head 10. Cabinet 10a Bottom surface of the housing (one end surface of the housing) 10b Ink passage hole 12 nozzles 13 Charged electrode 15 Deflection electrode 19 Air supply pipe 50 Air discharge member (air supply part) 50a Discharge surface 50b Ink ejection port 50c Air outlet 50d back 100 Controllers 104 Ink supply unit 104b Main tank (ink tank) 105 Solvent supply section 106 Air Pump Sa flight space S1 Ink space (internal space of the housing) S2 Ink ejection path S3 Air supply route

Claims

1. a vibration exciter that applies vibration to ink to be ejected and generates ink droplets; a nozzle connected to the vibration exciter that ejects the ink droplets generated by the vibration exciter; a charging electrode that is applied with a pulse voltage and charges the ink droplets by a potential difference generated by the pulse voltage; and a deflection electrode that deflects the ink droplets charged by the charging electrode in accordance with the amount of charge, causing the ink droplets to land on the surface of a workpiece; and a print head that houses the vibration exciter, the nozzle, the charging electrode, and the deflection electrode in an internal space and that extends in a longitudinal direction and has an ink ejection port formed therein for ejecting the charged ink droplets to the outside, an inkjet recording device that prints a character string by causing the ink droplets ejected from the print head to land on the workpiece moving in a direction perpendicular to the longitudinal direction, and causing a plurality of the ink droplets to land on a surface of the workpiece, The print head includes: a housing extending along the longitudinal direction and having an end surface that forms an opening through which the charged ink particles pass; a hollow air discharge member having a thin plate-like outer shape and attached to the end surface of the housing, The air discharge member has the ink ejection port; an air outlet surrounding the ink outlet; an air inlet connected to an air supply pipe for supplying air; an air supply path that communicates the air inlet and the air outlet is formed; Air is blown from the air outlet toward the workpiece. Inkjet recording device.

2. the air ejection member has an ejection surface on which the ink ejection port and the air ejection port are provided, the ejection surface having dimensions substantially equal to the end surfaces of the housing in two directions perpendicular to the longitudinal direction; The inkjet recording apparatus according to claim 1 .

3. an external air supply device communicates with the internal space, and air injected from the device is discharged to the outside via the internal space and the ink discharge port while printing a character string on the workpiece; 3. The inkjet recording apparatus according to claim 1 or 2.

4. an air pump for supplying air to the print head; a control unit that controls the charging electrode and the deflecting electrode to print a predetermined character string on the workpiece, and controls the air pump to supply air to the print head while the character string is being printed. The inkjet recording apparatus according to claim 1 .

5. a first air supply pipe communicating with the internal space; a second air supply pipe connected to the air inlet; a first air pump that supplies air to the internal space through the first air supply pipe; a second air pump that supplies air to the air inlet through the second air supply pipe, The inkjet recording apparatus according to claim 1 .

6. a charge detection sensor for monitoring the charge state of the ink particles charged by the charging electrode; a partition plate that divides the internal space into an ink space that houses the nozzle, the charging electrode, and the deflection electrode therein, and a circuit space that houses a circuit board to which the charge detection sensor is connected, the air discharge member forms the air inlet port ahead of the circuit space, and supplies air to the air discharge port formed ahead of the ink space via the air inlet port and the air supply path; The inkjet recording apparatus according to claim 1 .

7. A print head comprising: a vibrator that applies vibrations to ink to be ejected and generates ink droplets; a nozzle connected to the vibrator and that ejects the ink droplets generated by the vibrator; a charging electrode to which a pulse voltage is applied and that charges the ink droplets by a potential difference generated by the pulse voltage; and a deflection electrode that deflects the ink droplets charged by the charging electrode in accordance with the amount of charge and causes the ink droplets to land on the surface of a workpiece; the vibrator, nozzle, charging electrode and deflection electrode are housed in an internal space; and the print head extends in the longitudinal direction and has an ink ejection port formed therein for ejecting the charged ink droplets to the outside; an inkjet recording device that prints a character string by causing the ink droplets ejected from the print head to land on the workpiece moving in a direction perpendicular to the longitudinal direction, and causing a plurality of the ink droplets to land on a surface of the workpiece, The print head includes: a housing extending along the longitudinal direction and having an end surface that forms an opening through which the charged ink particles pass; an air discharge member attached to the end surface of the housing, The air discharge member has the ink ejection port; an air outlet surrounding the ink outlet; an air inlet connected to an air supply pipe for supplying air; an air supply path that communicates the air inlet and the air outlet is formed; a first air supply pipe communicating with the internal space; a second air supply pipe connected to the air inlet; a first air pump that supplies air to the internal space through the first air supply pipe; a second air pump that supplies air to the air inlet through the second air supply pipe, Air is blown from the air outlet toward the workpiece. Inkjet recording device.

8. A print head comprising: a vibrator that applies vibrations to ink to be ejected and generates ink droplets; a nozzle connected to the vibrator and that ejects the ink droplets generated by the vibrator; a charging electrode to which a pulse voltage is applied and that charges the ink droplets by a potential difference generated by the pulse voltage; and a deflection electrode that deflects the ink droplets charged by the charging electrode in accordance with the amount of charge and causes the ink droplets to land on the surface of a workpiece; the vibrator, nozzle, charging electrode and deflection electrode are housed in an internal space; and the print head extends in the longitudinal direction and has an ink ejection port formed therein for ejecting the charged ink droplets to the outside; an inkjet recording device that prints a character string by causing the ink droplets ejected from the print head to land on the workpiece moving in a direction perpendicular to the longitudinal direction, and causing a plurality of the ink droplets to land on a surface of the workpiece, The print head includes: a housing extending along the longitudinal direction and having an end surface that forms an opening through which the charged ink particles pass; an air discharge member attached to the end surface of the housing; a charge detection sensor for monitoring the charge state of the ink particles charged by the charging electrode; a partition plate that divides the internal space into an ink space that houses the nozzle, the charging electrode, and the deflection electrode therein, and a circuit space that houses a circuit board to which the charge detection sensor is connected, The air discharge member has the ink ejection port; an air outlet disposed ahead of the ink space and surrounding the ink outlet; an air inlet port disposed at the front end of the circuit space and connected to an air supply pipe for supplying air; an air supply path that communicates the air inlet and the air outlet is formed; Air supplied through the air inlet and the air supply path is blown from the air discharge port toward the workpiece. Inkjet recording device.

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