Inkjet recording device and inkjet head

Abstract

To provide an inkjet recording device and an inkjet head which can appropriately reduce variation in pressure of ink in a flow passage even under the condition of high frequency and high amplitude vibrations.SOLUTION: An inkjet recording device has an inkjet head that discharges ink and an ink flow passage extending from an ink supply source into the inkjet head, which is configured to supply ink to the inkjet head and eject ink, which is provided with a first air-retaining part connected to the ink flow passage through a first connection part extending in an extending direction which is a positive direction with respect to a flowing direction of ink and arranged in the extending direction which is the positive direction, and a second air-retaining part connected to the ink flow passage through a second connection part extending in an extending direction which is a negative direction with respect to the flowing direction of ink and arranged in the extending direction which is the negative direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to an inkjet recording apparatus and an inkjet head. [Background technology]

[0002] 2. Description of the Related Art Inkjet recording devices are known that form images on a recording medium by ejecting ink droplets from nozzles of an inkjet head. In an inkjet recording device, the pressure of ink supplied to the inkjet head fluctuates due to pulsation caused by an ink supply pump and acceleration / deceleration and vibration caused by the scanning operation of a carriage on which the inkjet head is mounted. Fluctuations in ink pressure cause the ink meniscus position of the ink in the nozzle of the inkjet head to shift, resulting in uneven density and making it difficult to eject the ink.

[0003] In order to reduce the pressure fluctuation of the ink, there are known inkjet recording devices equipped with air dampers as shown in Patent Documents 1 to 4. The air dampers in the inkjet devices shown in Patent Documents 1 to 4 have an air retention portion capable of retaining air on the ink flow path, and suppress the fluctuation of the ink pressure flowing to the inkjet head by using the expansion or contraction action of the air in this air retention portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-114737 A [Patent Document 2] Japanese Patent Application Publication No. 02-095863 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, as inkjet applications have become more diverse, the environments in which inkjet heads are used have become more severe, and they are required to be used under conditions in which they are subjected to unprecedented high-frequency, high-amplitude vibrations due to sudden acceleration / deceleration, movement in multiple axial directions, and disturbances such as vibrations and impacts.

[0006] Conventional air dampers reduce pressure fluctuations (dynamic pressure effects) of ink that occur in the ink flow path due to impacts, etc., caused by movement in either the positive or negative direction relative to the direction of ink supply to the inkjet head. For this reason, when used under conditions of unprecedented high-frequency, high-amplitude vibrations, there was a problem in that the pressure fluctuations occurring in the ink flow path could not be sufficiently suppressed.

[0007] The present disclosure has been made in consideration of the above problems, and aims to provide an inkjet recording device and an inkjet head that can suitably reduce pressure fluctuations of ink in a flow path even under high-frequency, high-amplitude vibration conditions. [Means for solving the problem]

[0008] The present disclosure, which solves the above-mentioned problems, is An inkjet head that ejects ink; an ink flow path configured to pass through the ink jet head from an ink supply source and supply ink to the ink jet head and discharge the ink; Has a first air holding portion that is connected to the ink flow path via a first connecting portion that extends in an extension direction of a positive direction with respect to a flow direction of ink and that is disposed in the extension direction of the positive direction; a second air holding portion connected to the ink flow path via a second connecting portion extending in a negative extension direction with respect to the flow direction and disposed in the negative extension direction; The inkjet recording apparatus includes:

[0009] In addition, the present disclosure mainly solves the above-mentioned problems. A nozzle for ejecting ink droplets; an ink flow path connected to an ink supply source and configured to pass through the nozzle, for supplying ink from the ink supply source to the nozzle and discharging the ink; a first air holding portion that is connected to the ink flow path via a first connecting portion that extends in an extension direction of a positive direction with respect to a flow direction of ink and that is disposed in the extension direction of the positive direction; a second air holding portion connected to the ink flow path via a second connecting portion extending in a negative extension direction with respect to the flow direction and disposed in the negative extension direction; The ink head is provided with: Effect of the Invention

[0010] According to the present disclosure, pressure fluctuations of ink in a flow passage can be suitably reduced even under high frequency, high amplitude vibration conditions. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a side view showing the overall configuration of an inkjet recording apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a front view of an inkjet recording apparatus according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a schematic diagram showing the configuration of a head unit of an inkjet recording apparatus according to an embodiment of the present invention; [Figure 4] FIG. 1 is a block diagram showing the main functional configuration of an inkjet printing apparatus according to an embodiment of the present invention. [Diagram 5] FIG. 1 is a schematic diagram showing a configuration of a main part of an ink circulation device having an air damper portion in an inkjet recording apparatus according to an embodiment of the present invention; [Figure 6] Enlarged schematic diagram of the air damper where ink flows in the forward direction [Figure 7] Enlarged schematic diagram of the air damper where ink flows in the negative direction [Figure 8] FIG. 13 is a diagram showing a modified example of an air damper portion in an inkjet recording apparatus according to an embodiment of the present invention. [Figure 9]FIG. 1 is a schematic diagram showing a modified example of an inkjet recording apparatus according to an embodiment of the present invention; [Figure 10] FIG. 1 is a diagram showing a schematic configuration of an inkjet head according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functions are designated by the same reference numerals, and redundant description will be omitted.

[0013] [Overall configuration of inkjet recording device] Hereinafter, the configuration of an inkjet recording apparatus 1 according to one embodiment of the present invention will be described with reference to FIGS.

[0014] FIG. 1 is a side view showing the overall configuration of an inkjet recording apparatus 1 according to this embodiment, and FIG. 2 is a front view of the same inkjet recording apparatus.

[0015] The inkjet recording apparatus 1 may be used, for example, as a drawing apparatus that uses a multi-axis robot arm to eject ink to color or draw on a target object such as a three-dimensional object. The inkjet recording apparatus 1 mainly includes a head unit 24 having a plurality of inkjet heads 240, a robot arm 5 that holds the head unit 24, a pinning device 6, a chamber 7, and a control unit 40 (see FIG. 4).

[0016] [Robot Arm 5] The robot arm 5 is a vertical articulated robot arm, and includes a base (foundation) part 51, a plurality of arms 52 connected by joints 53, a servo motor (not shown), and an encoder (not shown).

[0017] A plurality of arms 52 are connected to the base portion 51 via joints 53 on the base end side, and the inkjet head 240 and the pinning device 6 are held at the tip ends 520 of the arms 52.

[0018] Each joint 53 is composed of either a swing joint that allows one end of the arm 52 to swing and supports the other end, or a rotation joint that supports the arm 52 itself so that it can rotate about its longitudinal direction.

[0019] A servo motor is provided as a drive source for each joint 51, and rotates or turns the multiple arms 52 connected to each joint 51. The encoder detects the arm angles of each of the multiple arms 52. The servo motor is controlled by the control unit 40, and the encoder is connected to the control unit and outputs the detection result to the control unit 40 (see FIG. 4).

[0020] The robot arm 5 has, for example, six joints 53. The robot arm 5 can position the inkjet head 240 and the pinning device 6 at its tip 520 at any position by the six axes, and can make them take any posture.

[0021] Therefore, even if the surface of the printing object is, for example, a three-dimensional curved surface, the robot arm 5 can perform drawing by scanning the head unit 24 along any curve on the curved surface. Note that in this embodiment, "scanning" means performing drawing while moving the head unit 24.

[0022] The robot arm 5 is not limited to six axes, and may have one or more joints. For example, a seven-axis robot arm having seven joints may be used. When a robot arm having seven or more axes is used, which generates redundant joints, it becomes possible to position the inkjet head 240 and the pinning device 6 at any position and to move the intermediate joints while allowing them to take any posture. This allows the robot arm 5 to avoid interference with other objects in the vicinity, so that the inkjet head 240 and the pinning device 6 can be positioned at any position in a wider range and allowed to take any posture.

[0023] [Chamber 7] The chamber 7 is a storage room that stores the robot arm 5 and the printing object in a sealed state. The inside of the chamber 7 is sealed off from outside air and is dust-proof and moisture-proof. Inside the chamber 7, a work table 71 on which the printing object is placed is provided. The work table 71 may be provided with a jig that holds the printing object in a predetermined position.

[0024] [Head Unit 24] FIG. 3 is a schematic diagram showing the configuration of a head unit of an inkjet recording device according to one embodiment of the present invention. Specifically, FIG. 3 is a bottom view of the head unit 24 as seen from the direction of ink ejection by the inkjet head 240, showing the surface facing the object to be printed.

[0025] For the sake of convenience, the head unit 24 and inkjet head 240 described below will be described assuming that the drawing width direction, which is the arrangement direction (X direction) of the nozzles 243 of the inkjet head 240, is the left-right direction, the direction perpendicular to the left-right direction on a plane perpendicular to the ejection direction from the openings of the nozzles 243 is the front-rear direction (also called the scanning direction), and the direction perpendicular to the left-right direction and the front-rear direction (ejection direction) is the up-down direction. Note that these front-rear, left-right, up-down directions are directions defined for the head unit 24 and the inkjet head 240, and do not coincide with the front-rear, left-right, up-down directions in the description of the robot arm 5 above.

[0026] The head unit 24 has a plurality of inkjet heads 240, and is configured as a unit by integrally holding the inkjet heads 240 with their ejection directions aligned.

[0027] Here, the head unit 24 has four inkjet heads 240 attached to a mounting member 244, as shown in FIG. 3, and on the mounting member 244, two rows of inkjet heads 240 are arranged in a front-to-back manner, with the inkjet heads 240 lined up in the left-to-right direction.

[0028] In the head unit 24, the inkjet heads 240 are arranged so that the arrangement range of the nozzle rows in the X direction is continuous without breaks. Specifically, the inkjet heads 240 are arranged in a staggered pattern so that the nozzles 243 of the inkjet heads 240 in the front row do not overlap with the nozzles 243 of the inkjet heads 240 in the rear row when viewed from the front-to-rear direction. In this way, the head unit 24 forms a line head and performs one-pass printing using lines along the left-to-right direction. Note that the number of rows and columns of the inkjet heads 240 is merely an example and is not limited to the above description.

[0029] [Inkjet head 240] Each inkjet head 240 is provided with a plurality of image forming elements, each of which has a pressure chamber (not shown) for storing ink, a piezoelectric element (not shown) provided on the wall of the pressure chamber, and a nozzle 243. When a drive signal for deforming the piezoelectric element is input, the image forming element deforms the pressure chamber due to the deformation of the piezoelectric element, changing the pressure in the pressure chamber, and ejects ink from the nozzle 243 communicating with the pressure chamber. Note that in this embodiment, an example in which the number of rows of nozzles 243 in the mounting member 244 is two will be described, but the number of rows, number of rows, and arrangement of nozzles 243 in one row can be changed as appropriate, and for example, the number of rows may be one, four, six, or three or more rows.

[0030] The inkjet head 240 has an ink heating unit (not shown) that heats the ink stored in the inkjet head 240, so that the ink can be used for gel ink that becomes gelled when heated.

[0031] [Pinning device (irradiation unit) 6] The pinning device 6 is held at the tip of the robot arm 5 together with the head unit 24, and thickens the ink after it is ejected from the inkjet head 240. The pinning device 6 has an irradiation device that irradiates the ink after it is ejected from the inkjet head with any of energy rays such as infrared light (particularly, near-infrared light: wavelength of about 0.7 to 2.5 [μm]), ultraviolet light (wavelength of about 10 to 400 [nm]), and excimer emission.

[0032] The pinning device 6 irradiates the ink with energy rays, thereby thickening the ink on the surface of the print target. The pinning device 6 is not limited to an energy ray irradiation device of various kinds, and may be a heating device that heats the ejected ink. When the pinning device 6 is a heating device, it is preferable that the pinning device 6 is configured to include a heater element that serves as a heat source for heating the ink, and an air blower such as a fan that blows high-temperature air heated by the heater element onto the ink attachment position. This allows the ink to be effectively fixed by intensively applying high-temperature air to the ink on the surface of the print target to quickly dry it.

[0033] 4 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1 according to this embodiment. The inkjet recording apparatus 1 according to this embodiment includes a control unit 40, a head unit driving unit 3, a robot arm 5, a pinning device 6, and an ink supply unit 100.

[0034] The control unit 40 has a CPU (Central Processing Unit) 41, a RAM (Random Access Memory) 42, a ROM (Read Only Memory) 43, and a storage unit 44, and centrally controls the overall operation of the recording device 1. The CPU reads out various programs, data, etc. corresponding to the processing contents from a storage device such as a ROM, executes them, and controls the operation of each part of the inkjet recording device 1 according to the executed processing contents. The RAM temporarily stores various programs, data, etc. processed by the CPU. The ROM stores various programs, data, etc. read by the CPU, etc.

[0035] The control unit 40 performs operational control for drawing on the printing object based on three-dimensional data that defines the surface shape of the printing object and the range in which the drawing will be performed, as a basic control for performing drawing on the printing object. The three-dimensional data that defines the surface shape of the printing object and the range in which the drawing will be performed may be prepared in advance, or may be detected by a distance measuring device (not shown).

[0036] Specifically, the head unit driving unit 3 and the ink supply unit 100 are driven to eject ink from each nozzle 243 of the head unit 24, and near-infrared light is irradiated by the pinning device 6, while the robot arm 5 is controlled in operation to scan the inkjet head 240 forward or backward. The scanning of the inkjet head 240, that is, the scanning of the head unit 24, may be repeatedly performed while changing the position of the head unit 24 in the left-right direction.

[0037] Also, for example, the control unit 40 may acquire three-dimensional data of the surface shape of the object to be printed, and when the coordinates of the surface of the object to be printed can be expanded in the coordinate system of the robot arm 5, control the distance from each nozzle 243 to the surface of the object to be printed to maintain an appropriate ejection distance based on the surface position coordinates of the object to be printed.

[0038] This control eliminates the need for a device that measures the appropriate distance from each nozzle 243 to the surface of the print target, such as a two-dimensional or three-dimensional measuring device such as LiDAR (Laser Imaging Detection and Ranging).

[0039] On the other hand, if the configuration has a distance measuring device as this three-dimensional measurement device, the distance measuring device can control the robot arm 5 so that the distance from each nozzle 243 to the surface of the printing object in front is maintained at a predetermined (appropriate) discharge distance during discharge. As a result, the control unit 40 can control the robot arm 5 by comparing the distance to the surface of the printing object detected by the distance measuring device with the coordinates of the surface of the printing object expanded in the coordinate system of the robot arm 5, and using both.

[0040] The head unit driving section 3 supplies driving signals corresponding to image data (e.g., three-dimensional data) to be drawn at appropriate timing to the image forming elements of the head unit 24 under the control of the control section 40. This causes the head unit 24 to eject ink from the nozzles 243 in an amount corresponding to the pixel values ​​of the three-dimensional data.

[0041] [Ink supply unit 100] The ink supply unit 100 supplies ink stored in, for example, an ink storage unit 120 (see FIG. 5) connected to a main tank to each of the multiple inkjet heads 240 provided in the head unit 24. The ink supply unit 100 adjusts the amount of ink supplied to each of the multiple inkjet heads 240 using each unit in accordance with a control signal from the control unit 40.

[0042] [Configuration of ink supply unit 100] Fig. 5 is a diagram showing the main configuration of the ink supply unit 100 in the inkjet recording apparatus according to this embodiment. For convenience of explanation, only one inkjet head 240 is shown in Fig. 5, but a plurality of inkjet heads 240 (four in this case, as shown in Fig. 3) are provided in one head unit 24.

[0043] The ink supply unit 100 includes an ink storage unit 120, an ink flow path 400 (ink supply flow path 410, ink discharge flow path 420), an inkjet head 240, an air damper unit 300, and a waste liquid unit 160. The ink flow path 400 is preferably used as a circulation flow path for circulating ink. In that case, in the configuration shown in Fig. 5, a return pipe 170 is attached to the waste liquid unit 160 so as to communicate with it, and a suction device such as a pump is used to return ink from the waste liquid unit 160 through the return pipe 170 to the ink storage unit 120 (main tank or sub tank). The ink flow path 400 is configured by piping formed of, for example, a hose or pipe.

[0044] <Ink flow path 400> The ink flow path 400 is connected to an ink supply flow path 410 and an ink discharge flow path 420 (a first flow path 430, a second flow path 440, and a third flow path 450) to form a single flow path for flowing ink in one direction, the forward direction. In addition to the inkjet head 240 (specifically, a pressure chamber connected to the nozzle 243), the waste liquid section 160, and the air damper section 300 are arranged on this flow path.

[0045] The ink supply flow path 410 is a flow path upstream of the inkjet head 240 in the ink flow path 400, and supplies ink from the ink storage section 120 to the inkjet head 240 (a pressure chamber in the inkjet head 240). The ink supply flow path 410 is composed of a pipe section that connects the ink storage section 120 and the inkjet head 240.

[0046] The ink discharge flow path 420 is a flow path downstream of the inkjet head 240 in the ink flow path 400. For convenience, the ink discharge flow path 420 will be described separately as a first flow path 430, a second flow path 440, and a third flow path 450, but is actually composed of a tube that constitutes a single flow path.

[0047] An air damper unit 300 is disposed on the discharge flow path 420 (midway through the discharge flow path 420). The discharge flow path 420 discharges ink that has not been discharged from the nozzle 243 due to pressurization maintenance to the waste liquid section 160 via the first flow path 430, and the second flow path 440 and third flow path 450 in the air damper unit 300. The third flow path 450 connects the air damper unit 300 and the waste liquid section 160. The waste liquid section 160 stores ink that has not been ejected from the nozzle 243.

[0048] <Ink storage section 120> The ink storage unit 120 is a container for storing ink. The ink storage unit 120 is disposed in communication with a main tank and the inkjet head 240, and may be used to collect and circulate a part or all of the ink that is not ejected by the inkjet head 240. The ink storage unit 120 may be the main tank.

[0049] The ink stored in the ink storage section 120 is supplied to the inkjet head 240 via the ink supply flow path 410. At this time, the ink stored in the ink storage section 120 is supplied to the inkjet head 240.

[0050] The ink reservoir 120 is arranged, for example, in a sealed state, and stores ink with a predetermined amount of air space remaining inside. The air space may be arranged in a state of being sucked by a pump (not shown) so that a negative pressure state higher than the negative pressure of the nozzle back pressure of the inkjet head 240 is maintained. The pump may function as a back pressure control pump for the inkjet head 240.

[0051] The pump can adjust the back pressure of the inkjet head 240 by increasing or decreasing the pressure of the air layer in the ink storage unit 120, and can also control the pressure in the ink supply flow path 410. This pump is controlled by the control unit 40 so that the pressure of the inkjet head 240, that is, the pressure (meniscus pressure) at the opening of the nozzle 243 of the inkjet head 240, falls within the recommended meniscus pressure range for the inkjet head 240.

[0052] The inkjet head 240 ejects ink from a nozzle 243 connected to a pressure chamber connected to an ink supply flow path 410, and any ink ejected from the pressure chamber that is not ejected by the nozzle 243 due to pressurization maintenance flows through the ink discharge flow path 420 and is discharged to the waste liquid section 160.

[0053] <Air damper part> The air damper section 300 is disposed above the ink flow path 400 and reduces pressure fluctuations of the ink that fluctuate within the ink flow path 400, specifically, pressure fluctuations (dynamic pressure effects) that occur in the positive and negative directions of the ink flow within the ink flow path 400.

[0054] The air damper section 300 is disposed in the ink discharge flow path 420 downstream of the inkjet head 240 in the ink flow path 400. In terms of its function, the air damper section 300 is preferably disposed in a position close to the inkjet head 240, and is disposed at the tip portion 520 so as to make the length of the flow path from the pressure chamber (not shown) as short as possible.

[0055] FIG. 6 is an enlarged schematic view of an air damper portion where ink flows in the positive direction, and FIG. 7 is an enlarged schematic view of an air damper portion where ink flows in the negative direction.

[0056] The air damper section 300 has a damper body 310 through which an ink discharge flow path 420 passes, a first air holding chamber (air holding section) 320 and a second air holding chamber (air holding section) 330 connected to the ink flow path 400, a first connecting section 340 and a second connecting section 360.

[0057] A second flow path 440 constituting an ink discharge flow path 420 is inserted through the damper body 310. The first air holding chamber 320 is connected to this second flow path 440 via a first connecting portion 340, and the second air holding chamber 330 is connected to this second flow path 440 via a second connecting portion 360.

[0058] The first air holding chamber (first air holding portion) 320 is disposed in the second flow path 440 in an extension direction that is a positive direction with respect to the ink flow direction of the second flow path 440.

[0059] The first air holding chamber 320 reduces the ink pressure generated in the positive direction in the second flow path 440 (ink flow path 400). The first air holding chamber 320 is a sealed space connected to the first connecting portion 340 via an opening 324 in a bottom surface 322. The bottom surface 322 is configured as an inclined surface that slopes downward toward the opening 324.

[0060] That is, air holding chamber 320, which is the first air holding portion, includes an inclined surface that slopes down toward first connecting portion 340 to which the first air holding portion is connected in a vertically downward direction. Since ink flows along this inclined surface during pressurization maintenance of first air holding chamber 320, ink that has temporarily flowed in can be easily discharged. This makes it possible to extend the life of first air holding chamber 320.

[0061] The first connecting portion 340 is a tubular portion extending in the extension direction of the positive ink flow from the second flow path 440, and branches off from the second flow path 440 in the positive ink flow direction to connect the first air holding chamber 320 to the second flow path 440.

[0062] The cross-sectional area of ​​the first connecting portion 340 is formed to be smaller than the cross-sectional area of ​​the second flow path 440. In other words, the cross-sectional area of ​​the first connecting portion 340 is smaller than the cross-sectional area of ​​the connection portion of the second flow path 440, which is the ink flow path to which the first connecting portion 340 is connected. This reduces the flow of ink into the first air holding chamber 320 when ink is circulated around the air damper portion 300, suppresses the dissolution of air into the ink in the first air holding chamber 320, and extends the life of the first air holding chamber 320.

[0063] The first connecting portion 340 is connected to the first air holding chamber 320 in a vertically upward direction, and this configuration also reduces the flow of ink into the first air holding chamber 320 and suppresses the dissolution of air into the ink within the first air holding chamber 320.

[0064] The second air holding chamber (second air holding portion) 330 is disposed in the second flow path 440 in an extension direction that is a negative direction with respect to the ink flow direction of the second flow path 440.

[0065] 7, the second air holding chamber 330 reduces the ink pressure generated in the second flow path 440 (ink flow path 400) in the negative direction. The second air holding chamber 330 is a sealed space connected to the second connecting portion 360 via an opening 334 in the bottom surface 332.

[0066] The bottom surface 332 is configured as an inclined surface with a downward gradient that descends toward the opening 334. That is, the air holding chamber 330, which is the second air holding portion, includes an inclined surface that descends toward the second connecting portion 360 to which the air holding chamber 330 is connected in a vertically downward direction. As with the bottom surface 322, which is the inclined surface of the first air holding chamber 320, this inclined surface allows ink to flow along the inclined surface during pressurization maintenance of the second air holding chamber 330, so that ink that has temporarily flowed in can be easily discharged. This makes it possible to extend the life of the second air holding chamber 330. This inclined surface makes it possible to reduce the flow of ink into the second air holding chamber 330, thereby extending the life of the second air holding chamber 330.

[0067] The second connecting portion 360 is a tubular portion extending in the extension direction of the negative ink flow from the second flow path, and branches off from the second flow path 440 in the negative ink flow direction to connect to the second air holding chamber 330.

[0068] The cross-sectional area of ​​the second connecting portion 360 is formed to be smaller than the cross-sectional area of ​​the second flow path 440, that is, the cross-sectional area of ​​the ink supply flow path 410. In other words, the cross-sectional area of ​​the second connecting portion 360 is smaller than the cross-sectional area of ​​the connection portion of the second flow path 440, which is the ink flow path to which the second connecting portion 360 connects. This reduces the flow of ink into the second air holding chamber 330 when ink is circulated around the air damper portion 300, suppresses the dissolution of air into the ink in the second air holding chamber 330, and enables the second air holding chamber 330 to have a longer life.

[0069] The second connecting portion 360 is connected to the second air holding chamber 330 in a vertically upward direction, and this configuration also reduces the flow of ink into the second air holding chamber 330 and suppresses the dissolution of air into the ink in the second air holding chamber 360.

[0070] The first air holding chamber 320 and the second air holding chamber 330 may have an opening valve that can be opened and closed. With this, when the internal air of each of the air holding chambers 320, 330 is reduced, the internal air can be replenished by pressurizing the first air holding chamber 320 and the second air holding chamber 330 via the opening valve during maintenance, and internal ink can be removed, etc.

[0071] <Operation of the air damper unit 300> Generally, the pressure generated in the ink flowing through the ink flow path 400 of the inkjet recording device 1 includes static pressure, which is the compression energy per unit volume, and dynamic pressure, which is the kinetic energy per unit volume. Dynamic pressure cannot become pressure while the fluid is moving, but becomes pressure when the movement is interrupted. In the inkjet recording device 1, dynamic pressure occurs as pressure fluctuations caused by the ink moving through the flow path due to sudden acceleration / deceleration, movement in multiple axial directions, and disturbances such as vibrations and impacts.

[0072] The movement of ink (ink flow) in the ink flow path 400 has a positive direction, which is the ink supply direction, and a negative direction, which is the opposite direction.

[0073] When a high-frequency, high-amplitude vibration is applied to the ink flow path 400 due to a disturbance such as an impact applied to the tip portion 520, a positive ink pressure fluctuation and a negative ink pressure fluctuation may occur in the ink flow path 400.

[0074] When a positive pressure fluctuation occurs, in the air damper section 300, as shown in FIG. 6, the pressure fluctuation is reduced by the first air holding chamber 320 which is connected to the second flow path 440 of the ink flow path 400 via a first connecting portion 340 extending in the positive direction of the ink flow in the ink flow path 400.

[0075] In addition, when a negative pressure fluctuation occurs, in the air damper section 300, as shown in FIG. 7, the pressure fluctuation is reduced by the second air holding chamber 330 via the second connecting section 360 connected to the second flow path 440 of the ink flow path 400 via the second flow path 440 extending in the negative direction of the ink flow in the ink flow path 400.

[0076] In this manner, in the air damper portion 300, the first and second air holding chambers 320, 330 are provided in the ink flow path 400 (second flow path 440) branching in the positive or negative direction of the ink flow.

[0077] This makes it possible to reduce pressure fluctuations (due to the influence of dynamic pressure) that occur within the ink flow path 400, which is subjected to high-frequency, high-amplitude acceleration when a high-frequency, high-amplitude disturbance is applied to the tip portion 520 due to an impact or the like. In this way, even when vibrations due to high-frequency, high-amplitude disturbances are applied to the tip portion 520, the pressure fluctuations within the ink flow path 400 can be reduced, and the meniscus of the nozzle 243 of the inkjet head 240 can be prevented from being broken, making it possible to stabilize the ejection state.

[0078] In the inkjet recording apparatus 1, the damper section 300 can be effectively used not only when the vibration period applied to the ink flow path 400 and the inkjet head 240 is less than 10 Hz, but also when the vibration period is 10 Hz or more.

[0079] The ink pressure fluctuations that occur when vibrations (dynamic pressure) with a period within this range are applied to the ink flow path 400 and the inkjet head 240 are reduced (damped) by the air damper section 300, allowing the ink to be ejected stably from the inkjet head 240. Furthermore, in the inkjet recording apparatus 1, even if the acceleration applied to the ink flow path 400 and the inkjet head 240 is 2G or more, the inkjet recording apparatus 1 can be effectively used in response to this.

[0080] Even when vibrations in this range are applied to the tip portion 520 and the ink flow path 400, the air damper portion 300 can reduce the pressure fluctuations of the ink in the ink flow path 400.

[0081] The normal scanning operation of the tip portion 520 has a maximum frequency of about 0.5 Hz and an amplitude of about 1 to 1.5 G. Even if vibrations of higher frequency and amplitude than these are received, the fluctuating dynamic pressure of the ink generated can be effectively reduced, and ink can be stably ejected from the nozzles 243 of the inkjet head 240.

[0082] <Modification of the air damper part> FIG. 8 is an enlarged view of a main portion for explaining a modified example of the air damper portion. As shown in FIG. 8, in the air damper section 300, it is preferable that the extension direction of the first connecting section 340 and the second connecting section 360 extending from the second flow path 440 is greater than -45° indicated by -α and less than +45° indicated by +α with respect to the ink flow direction.

[0083] When the extension direction of the first connecting part 340 and the second connecting part 360 is −45° or less or +45° or more with respect to the ink flow direction being 0°, it becomes difficult for fluid such as ink generated in the ink flow path 400 to flow through the connecting parts 340 and 360. As a result, it becomes difficult to reduce the pressure fluctuation of the ink.

[0084] Furthermore, it is preferable that the extension direction of the first connecting portion 340 and the second connecting portion 360 is greater than -α and greater than +α, and is greater than -30° indicated by -β and less than +30° indicated by +β. In this way, even if the extension direction extending from the first connecting portion 340 and the second connecting portion 360 is not parallel to the flow of ink, the first air holding chamber 320 and the second air holding chamber 330 can provide the same effect.

[0085] In the inkjet recording apparatus 1 of the present embodiment, the air damper section 300 is arranged in the discharge flow path 420 downstream of the inkjet head 240, but this is not limiting. The air damper section 300 may be arranged in a flow path upstream of the inkjet head 240, specifically, in the ink supply flow path 410.

[0086] <Modification of Inkjet Recording Apparatus> Fig. 9 is a diagram showing a schematic configuration of a modified inkjet recording apparatus according to an embodiment of the present invention. In the inkjet recording apparatus 1A shown in Fig. 9, in the configuration of the inkjet recording apparatus 1, the ink supply section 100A has an air damper section 300A between the upstream section 412 and the downstream section 414 of the ink supply flow path 410A.

[0087] In the inkjet recording device 1A, air damper sections 300A, 300 are arranged in the flow paths upstream and downstream of the inkjet head 240 at the tip portion 520A, so that the fluctuating dynamic pressure of the ink generated in the ink flow path 400 can be more effectively reduced, i.e., damped.

[0088] In addition, in this embodiment, it is preferable to place the air damper portion 300, 300A in a position close to the inkjet head 240, so in the inkjet recording apparatus 1, 1A, it is provided at the tip portion 520, 520A so as to be located in a close or adjacent position, but this is not limited to this.

[0089] The above-mentioned air damper portion 300 may be provided in the inkjet head 240 .

[0090] <Inkjet head 240B> Fig. 10 is a diagram showing a schematic configuration of an inkjet head 240B according to an embodiment of the present invention. The inkjet head 240B shown in Fig. 10 has an air damper unit 300B, and can be used in the inkjet recording apparatus 1 by modifying the inkjet head 240 and removing the air damper unit 300.

[0091] The inkjet head 240B has a head body 2402, which is an inkjet head body, a nozzle 243 for ejecting ink droplets, an ink flow path 400B, and an air damper section 300B having a similar configuration to the air damper section 300.

[0092] The ink flow path 400B can be connected at both ends to an external device or an external member, and one end is connected to an ink supply source (for example, the ink storage section 120) and is connected to a pressure chamber in the head main body 2402. The pressure chamber is connected to a nozzle (nozzle surface 243a).

[0093] The ink flow path 400B has an ink supply path 410B that supplies ink from an ink supply source to the nozzles (nozzle surface 243a), and an ink discharge path 430B that discharges ink from the nozzles (nozzle surface 243a).

[0094] The air damper section 300B has the same components as the air damper section 300, and includes a first air holding chamber 320B, a first connecting section 340B, an air holding chamber 320B, and a second connecting section 360B.

[0095] The first air holding chamber 320B is arranged on the ink flow path 400 (more specifically, the second flow path 430B) in the extension direction in the positive direction (positive direction) relative to the ink flow direction, and is connected via a first connecting portion 340B extending in the positive extension direction.

[0096] The second air holding chamber 330B is disposed on the ink flow path 400 (specifically, the second flow path 430B) in an extension direction in a negative direction (negative direction) with respect to the ink flow direction, and is connected via a second connecting part 360B extending in the negative extension direction. That is, the inkjet head 240B includes a first air holding part disposed in an extension direction in a positive direction with respect to the ink flow direction, and communicating with the ink flow path in the positive direction via the first connecting part, and a second air holding part disposed in an extension direction in a negative direction with respect to the ink flow direction, and communicating with the ink flow path in the negative direction via the second connecting part.

[0097] As a result, by using the inkjet head 240B as part of a circulation flow path that supplies ink to the inkjet head 240B in the ink supply section 100 of the inkjet recording device, it is possible to reduce pressure fluctuations of the ink within the circulation flow path, and to obtain the same effects as those of the inkjet recording device 1 described above.

[0098] Although the specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above. [Industrial Applicability]

[0099] According to the inkjet recording device of the present disclosure, it is possible to prevent the ink meniscus formed in the nozzle of the inkjet head from being destroyed when the ink circulation operation in the ink supply flow path is stopped. [Explanation of symbols]

[0100] 1. 1A Inkjet recording device 3 Head unit drive 5. Robot Arm 6 Pinning device 7. Chambers 24 Head Unit 40 Control section 44 Memory section 51 Foundation 52 Arm 53 Joints 71 Workbench 100 Ink supply unit 120 Ink storage unit 160 Waste liquid section 170 Return pipe 240, 240B Inkjet Head 243 Nozzle 243a Nozzle surface 244 Mounting material 300, 300B Air damper part 310 Damper body 320, 320B First air holding chamber (air holding section) 322 Bottom 324, 334 opening 330 Second air holding chamber (air holding section) 340, 340B First communication part 360, 360B Second connection part 400, 400B Ink flow path 410, 410B Ink supply channel 420 Ink discharge flow path 423 Nozzle 430, 430B First flow path 440 Second Stream 450 3rd Stream 2402 Head body 520 Tip

Claims

1. An inkjet head that ejects ink; an ink flow path configured to pass through the ink jet head from an ink supply source and supply ink to the ink jet head and discharge the ink; Has a first air holding portion that is connected to the ink flow path via a first connecting portion that extends in an extension direction of a positive direction with respect to a flow direction of ink and that is disposed in the extension direction of the positive direction; a second air holding portion connected to the ink flow path via a second connecting portion extending in a negative extension direction with respect to the flow direction, and disposed in the negative extension direction; Equipped with Inkjet recording device.

2. the first and second air holding portions are provided in an ink discharge flow path in the ink flow path, which discharges the ink from the inkjet head; 2. The ink jet recording apparatus according to claim 1.

3. a cross-sectional area of ​​the first and second connecting portions is smaller than a cross-sectional area of ​​a connecting portion of the ink flow path to which the first and second connecting portions are connected, 2. The ink jet recording apparatus according to claim 1.

4. The extension directions of the first and second connecting portions are at an angle of ±30° or less with respect to the ink flow direction.

2. The ink jet recording apparatus according to claim 1.

5. The first and second connecting portions are connected to the first and second air holding portions in a vertically upward direction.

2. The ink jet recording apparatus according to claim 1.

6. The first and second air holding portions include inclined surfaces that descend toward the first and second connecting portions to which the first and second air holding portions are connected in a vertically downward direction.

2. The ink jet recording apparatus according to claim 1.

7. A nozzle for ejecting ink droplets; an ink flow path connected to an ink supply source and configured to pass through the nozzle, for supplying ink from the ink supply source to the nozzle and discharging the ink; a first air holding portion that is connected to the ink flow path via a first connecting portion that extends in an extension direction of a positive direction with respect to a flow direction of ink and that is disposed in the extension direction of the positive direction; a second air holding portion connected to the ink flow path via a second connecting portion extending in a negative extension direction with respect to the flow direction, and disposed in the negative extension direction; Equipped with Inkjet head.

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