Inkjet head, line head, inkjet device, and method for manufacturing an inkjet head

Abstract

To provide an inkjet head capable of high-resolution printing. [Solution] The inkjet head comprises a plurality of drive unit rows arranged at a pitch p, and a plurality of nozzles positioned at positions corresponding to each drive unit, which eject ink by the drive of the drive unit. The plurality of drive unit rows include a first drive unit row and a second drive unit row arranged on the same straight line, and the shortest distance D between a drive unit located on the second drive unit row side of the first drive unit row and a drive unit located on the first drive unit row side of the second drive unit row is a non-integer multiple of the pitch p.

Description

Technical Field

[0001] The present disclosure relates to an inkjet head, a line head, an inkjet device, and a method for manufacturing an inkjet head.

Background Art

[0002] In recent years, a method of manufacturing a device using an inkjet device has attracted attention. An inkjet device has a plurality of nozzles that eject droplets, and applies droplets to a printing object by ejecting droplets from the nozzles while controlling the positional relationship between the nozzles and the printing object.

[0003] As one type of this kind of inkjet device, there is a so-called line head that includes a plurality of module heads (that is, droplet ejection heads having a plurality of ejection ports) arranged side by side in the width direction of the printing object.

[0004] By arranging these line heads side by side in a direction orthogonal to the printing direction, ink can be collectively applied to a large-width printing object in a single conveyance step. Further, by mounting a plurality of line heads arranged side by side also in the printing direction, a plurality of inks of different colors can be collectively applied to the printing object in a single conveyance step.

[0005] According to this configuration, for example, a plurality of inks can be collectively applied to a large printing object of G8 size or more in a single conveyance step, so that it is possible to reduce the tact of applying ink to the printing object, and it is easy to make the drying conditions after ink application uniform. Therefore, there are advantages in the printing process such as being able to uniformly control the ink film thickness.

[0006] Here, in order to accommodate the increasing resolution of the printed object, it is desirable to increase the nozzle density in the direction perpendicular to the printing direction (i.e., the resolution of the ejection nozzles in the line head). On the other hand, from the standpoint of preventing printing inconsistencies, it is desirable to reduce the distance between nozzles in the printing direction (i.e., the depth of the printing area in the line head). For example, it is desirable for the nozzle resolution to be 2400 dpi and the depth of the printing area in the line head to be 80 mm or less.

[0007] Another way to improve the resolution of the discharge nozzles is to narrow the pitch between adjacent nozzles. However, there is a problem in that the discharge accuracy deteriorates due to the mutual influence between adjacent nozzles called crosstalk, and there are limits to how narrow the nozzle pitch can be.

[0008] On the other hand, inkjet devices with ingenious nozzle arrangements are known (see, for example, Patent Document 1). As described in Patent Document 1, by arranging the inkjet head diagonally with respect to the printing direction and arranging the nozzle rows with a phase shift, the depth of the printing area of ​​the line head can be reduced and the nozzle resolution can be increased to about 1200 dpi. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 5857205 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, in order to achieve even higher resolutions by increasing the tilt angle of the inkjet head, it is necessary to lengthen the nozzle row, which leads to the problem of increasing the size of the inkjet head and the depth of the print area of ​​the line head. As mentioned above, narrowing the nozzle pitch is also a possible method, but there are limits to this.

[0011] This disclosure aims to provide an inkjet head, a line head, an inkjet device, and a method for manufacturing an inkjet head that enable high-definition printing while simultaneously achieving miniaturization of the inkjet head and reduction of the depth width in the printing area of ​​the line head. [Means for solving the problem]

[0012] The inkjet head of this disclosure comprises a plurality of drive unit rows arranged at a pitch p, and a plurality of nozzles positioned corresponding to each of the drive units and ejecting ink by the drive of the drive units, wherein the plurality of drive unit rows have a first drive unit row and a second drive unit row arranged on the same straight line, and the shortest distance D between a drive unit located on the second drive unit row side of the first drive unit row and a drive unit located on the first drive unit row side of the second drive unit row is a non-integer multiple of the pitch p.

[0013] The line head of this disclosure comprises a plurality of the above-described inkjet heads.

[0014] The method for manufacturing an inkjet head according to the present disclosure involves joining the drive unit and a member constituting a pressure chamber for storing the ink with a thermosetting adhesive that hardens at a temperature of 70°C or less in between, and then thermosetting the thermosetting adhesive at a temperature of 70°C or less to manufacture the inkjet head. [Effects of the Invention]

[0015] According to the inkjet head, line head, inkjet device, and method for manufacturing an inkjet head of this disclosure, high-definition printing is possible while simultaneously achieving miniaturization of the inkjet head and reduction of the depth width in the printing area of ​​the line head. [Brief explanation of the drawing]

[0016] [Figure 1] A plan view of an inkjet printer. [Figure 2]Exploded perspective view showing the overall structure of the inkjet head [Figure 3] Cross-sectional view of the vicinity of the nozzles of the inkjet head [Figure 4A] Cross-sectional view showing an example of a cross-section of the driving body shown in Fig. 3 cut along the YZ plane [Figure 4B] Cross-sectional view showing an example of a cross-section of the driving body shown in Fig. 3 cut along the YZ plane [Figure 4C] Diagram showing an example of the configuration when the control wiring is a flexible printed circuit board [Figure 5A] Diagram explaining the processing method of the driving part when there is a column part [Figure 5B] Diagram explaining the processing method of the driving part when there is no column part [Figure 6A] Diagram explaining the driving part of the thermal jet method [Figure 6B] Diagram explaining the driving part of the shear mode method [Figure 6C] Diagram explaining the driving part of the vent method [Figure 6D] Diagram explaining the time division injection control for the driving part of the share mode method [Figure 7] Diagram explaining the relationship between the inkjet head and the driving body [Figure 8A] Diagram explaining the arrangement method of the driving part [Figure 8B] Diagram showing the positional relationship between the driving body and the inkjet head [Figure 8C] Diagram showing the case where the inkjet head is arranged obliquely with respect to the printing direction [Figure 8D] Diagram explaining the nozzle array for realizing high-definition printing [Figure 9A] Diagram explaining the relationship between the arrangement of the driving part and the printing resolution [Figure 9B] Diagram explaining the nozzle array for realizing high-definition printing [Figure 9C] Diagram showing four nozzle arrays provided on the driving body cut out when a plurality of inkjet heads are arranged in parallel [Figure 9D]This diagram shows the position of the nozzles in the Y' direction within each nozzle row. [Figure 10A] A diagram showing a first modified example of the configuration of the drive unit and drive unit array. [Figure 10B] This figure shows a second modified example of the configuration of the drive unit and drive unit array. [Figure 10C] A diagram showing a third modified example of the configuration of the drive unit and drive unit array. [Figure 10D] A figure showing a fourth modified example of the configuration of the drive unit and drive unit array. [Figure 10E] This figure shows an example of a nozzle array when a single drive unit has multiple drive unit arrays in the X direction. [Figure 10F] This figure shows a fifth modified example of the configuration of the drive unit and drive unit array. [Figure 10G] A diagram showing a sixth modified example of the configuration of the drive unit and drive unit array. [Figure 11] A diagram explaining how to deal with warping of the drive unit itself. [Modes for carrying out the invention]

[0017] The inkjet head in the embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to the embodiments described below, and can be modified in various ways without departing from the spirit of this disclosure.

[0018] First, the inkjet device 1 will be described with reference to Figure 1. Figure 1 is a plan view of the inkjet device 1. As shown in Figure 1, the longitudinal direction of the inkjet device 1 is the X' direction, the transverse direction is the Y' direction, and the direction perpendicular to the X' and Y' directions is the Z direction.

[0019] The inkjet printer 1 comprises a base 2, a guide 3, a transport table 4, a gantry 5, a head unit 6, and a drive unit 8.

[0020] The base 2 is a rectangular prism-shaped platform with a long rectangular planar shape in the scanning direction (X' direction) of the head unit 6.

[0021] Guide 3 is fixed to the upper surface of base 2 along the scanning direction of head unit 6. As an example, guide 3 is a rectangular parallelepiped with a rectangular cross-section perpendicular to the scanning direction.

[0022] The transport table 4 has a rectangular shape, and its lower surface (the -Z side) is in contact with the guide 3. The transport table 4 is guided by the guide 3 and transported in the scanning direction of the base 2. A printing object 7, such as a circuit board, is placed on the transport table 4.

[0023] The gantry 5 has a gate-like shape and is a support member that supports the head unit 6. In a plan view (when viewed from the +Z side), the gantry 5 is fixed to a predetermined position on the base 2, for example, an intermediate position, so as to straddle the shorter side of the base 2.

[0024] The head unit 6 is an example of an ink ejection head and is supported by the gantry 5. The head unit 6 ejects ink toward the print object 7 in time with the print object 7 passing beneath the head unit 6. This coats the print area of ​​the print object 7 with ink.

[0025] For example, the head unit 6 is a line head equipped with multiple inkjet heads 100, which will be described later.

[0026] In this configuration, as shown in Figure 1, two head units 6 are arranged on both sides of the gantry 5. However, only one head unit 6 may be arranged on the gantry 5, or two gantry 5 may be arranged, with a head unit 6 on both sides of each gantry 5. The number and arrangement of head units 6 may be changed depending on the processing performed by the head units 6 on the object to be printed 7.

[0027] Furthermore, in order to drive the transport table 4 in the scanning direction, at least one drive device 8 is arranged on the base 2 along the scanning direction and connected to the transport table 4 to transport and drive the transport table 4 in the scanning direction.

[0028] In Figure 1, as an example of a drive device 8, two drive devices 8 extending in the scanning direction are arranged near both ends in the short direction of the base 2. Each drive device 8 may be a linear motor, or it may be a ball screw connected to a rotary motor, etc. In this configuration, the case where the drive device 8 is a linear motor is illustrated as an example.

[0029] Here, the drive unit 8 moves the transport table 4 relative to the head unit 6, but the inkjet device 1 can simply move the head unit 6 and the transport table 4 relative to each other.

[0030] Furthermore, as shown in Figure 1, if the head unit 6 is a line head type head unit that is positioned across the entire width in the Y' direction of the inkjet device 1, the head unit 6 can apply ink to the print target 7 all at once, thus enabling efficient printing of large quantities of printed materials.

[0031] On the other hand, there are cases where the head unit 6 is not positioned across the entire width in the Y' direction of the inkjet device 1. In this case, the inkjet device 1 performs printing using a multi-scan method.

[0032] In multi-scan printing, the print head unit 6 moves back and forth multiple times over the object 7 to print multiple lines. Therefore, the inkjet device 1 can precisely print specific areas, reducing ink waste and lowering costs. This type of multi-scan printing is sometimes called swaz printing.

[0033] Next, the overall configuration of the inkjet head 100 mounted on the head unit 6 will be described. Figure 2 is an exploded perspective view showing the overall configuration of the inkjet head 100. In Figure 2, the Cartesian coordinate system, where coordinates are represented as (X,Y,Z), will be used for explanation.

[0034] In Figure 2, the +Z direction is the direction in which the inkjet head 100 ejects ink, the Y direction is the longitudinal direction of the inkjet head 100 (the direction of nozzle arrangement), and the X direction is the width direction of the inkjet head 100. The Z direction is the stacking direction of the plates, which are components of the inkjet head 100.

[0035] The inkjet head 100 includes a housing section 10, a vibrating plate 20, a flow path plate 30, a nozzle plate 40, a drive unit 50, a base section 60, and an FPC (flexible printed circuit board) section 80.

[0036] The drive unit 50 is located at the lower end of the base unit 60. The upper part of the housing unit 10 is open, and the housing unit 10 accommodates the drive unit 50 and the base unit 60 through this opening. The FPC unit 80 is connected to the drive unit 50 and provides electrical connections between each drive unit provided on the drive unit 50 and a control unit (not shown).

[0037] On the lower side of the housing portion 10, there is a flow path portion 70 via a vibrating plate 20. The flow path portion 70 has a flow path plate 30 and a nozzle plate 40. The vibrating plate 20, the flow path plate 30 and the nozzle plate 40 are fixed in a sequentially stacked state.

[0038] The nozzle plate 40 and the flow path plate 30, the flow path plate 30 and the vibrating plate 20, the vibrating plate 20 and the housing portion 10, the vibrating plate 20 and the drive unit 50, the base portion 60 and the vibrating plate 20, and the base portion 60 and the drive unit 50 are each fixed to each other via adhesive or the like.

[0039] As an adhesive, for example, an epoxy adhesive with thermosetting properties can be used. The same adhesive may be used to join each component, or different adhesives may be used for each component. For example, a combination of a rubber-based adhesive and an epoxy-based adhesive may be used.

[0040] Next, the configuration near the nozzle of the inkjet head 100 will be described. Figure 3 is a cross-sectional view of the vicinity of the nozzle 41 of the inkjet head 100.

[0041] The nozzle plate 40 is formed, for example, by shaping a stainless steel plate with a thickness of 100 μm through etching or press working. Multiple nozzles 41 are drilled into the nozzle plate 40 in the Y direction.

[0042] The flow channel plate 30 has a rectangular parallelepiped shape. The flow channel plate 30 is formed by laminating stainless steel plate members with a thickness of 10 to 100 μm, which are formed, for example, by etching or press working. The number of layers is, for example, 3 to 10.

[0043] The flow path plate 30 has a plurality of pressure chambers 33 that are connected to a plurality of nozzles 41 in a one-to-one ratio, and a silo section 36 that connects the pressure chambers 33 to the nozzles 41.

[0044] The pressure chamber 33 is formed in the flow path plate 30 in a rectangular parallelepiped shape extending in the X direction, and the upper wall forming the upper (-Z direction) surface is constructed by the vibration plate 20. Note that the pressure chamber 33 may not be a rectangular parallelepiped, but may have multiple steps inside.

[0045] The silo section 36 connects the pressure chamber 33 and the nozzle 41 and stores ink. The silo section 36 is formed along the Z direction.

[0046] The flow path plate 30 has upstream individual flow path sections 32 that are individually connected one-to-one with the pressure chamber 33 on the upstream side, an upstream common flow path section 31 that is connected to multiple upstream individual flow path sections 32, downstream individual flow path sections 34 that are individually connected one-to-one with the pressure chamber 33 on the downstream side, and a downstream common flow path section 35 that is connected to multiple downstream individual flow path sections 34.

[0047] The vibrating plate 20 is, for example, a thin film with a thickness of 5 to 50 μm, and is made of, for example, Ni. The vibrating plate 20 also has an upstream opening 21 located directly above (-Z direction) the upstream common flow channel section 31 and a downstream opening 22 located directly above (-Z direction) the downstream common flow channel section 35.

[0048] The housing portion 10 is formed in the shape of a rectangular parallelepiped. The housing portion 10 is formed by machining an alloy steel such as stainless steel. The housing portion 10 has a thickness in the Z direction of, for example, about 1 cm.

[0049] The housing portion 10 has an upstream common channel 12 located directly above the upstream opening 21 (in the -Z direction) and a downstream common channel 14 located directly above the downstream opening 22 (in the -Z direction).

[0050] The upstream common channel L1 is formed by the upstream common channel 12 of the housing section 10, the upstream opening 21 of the vibrating plate 20, and the upstream common channel section 31 of the channel plate 30. Furthermore, the downstream common channel L2 is formed by the downstream common channel 14 of the housing section 10, the downstream opening 22 of the vibrating plate 20, and the downstream common channel section 35 of the channel plate 30.

[0051] Furthermore, the housing section 10 has an ink introduction passage (not shown) for introducing ink from the outside and an ink discharge passage (not shown) for discharging ink to the outside. The ink introduced into the upstream common flow path L1 via the ink introduction passage is discharged from the ink discharge passage after passing through the upstream common flow path L1, the upstream individual flow path section 32, the pressure chamber 33, the downstream individual flow path section 34, and the downstream common flow path L2 in that order.

[0052] The drive unit 50 is positioned inside the housing 10 and imparts pressure fluctuations to the ink in the pressure chamber 33. These pressure fluctuations propagate towards the nozzle 41, causing ink to be ejected from the nozzle 41.

[0053] The vibrating plate 20 has protrusions 24 that extend in the -Z direction, and these protrusions 24 input the fluctuations of the drive unit 50. Multiple protrusions 24 are formed in the Y direction at positions corresponding to the nozzle 41.

[0054] The drive unit 50 is composed of piezoelectric elements. Specifically, the drive unit 50 has electrode layers 52 and 53 inserted into the piezoelectric elements and has a drive unit (not shown) that is driven by applying an electrical signal to the electrode layers 52 and 53. The drive unit is provided in a one-to-one correspondence with the nozzle 41 and is separated into multiple channels by notches (not shown).

[0055] The drive unit 50 is a piezoelectric element supported by a base unit 60. The base unit 60 is a support that supports the drive unit 50. Control wiring 51 for controlling the drive unit 50 is attached to the drive unit 50. The control wiring 51 and the drive unit 50 are electrically connected. The control wiring 51 corresponds to the FPC unit 80 shown in Figure 2.

[0056] The drive unit 50 is positioned to contact, via adhesive, a protrusion 24 of the vibrating plate 20 that constitutes the upper side wall (-Z direction side wall) of the pressure chamber 33. When a voltage is applied, the drive unit 50 deforms to expand and contract along the Z direction. The drive unit 50 is, for example, a D33 mode laminated piezoelectric actuator.

[0057] The drive unit 50 deforms to extend along the Z direction, pushing the protrusion 24 downward (in the +Z direction). This deforms the upper wall (-Z direction wall) of the pressure chamber 33, causing pressure fluctuations in the ink within the pressure chamber 33.

[0058] This pressure fluctuation is transmitted to the nozzle 41 via the silo section 36, causing ink to be ejected from the nozzle 41 to the outside. In this way, the operation of the drive unit 50 controls the ejection of ink.

[0059] Next, the configuration of the drive unit 50 and the flexible substrate that connects the drive unit 50 and the control wiring 51 will be described using Figures 4A to 4C. Figures 4A and 4B are cross-sectional views showing an example of a cross-section of the drive unit 50 shown in Figure 3, cut in the YZ plane. Figure 4C is a diagram showing an example of the configuration of the flexible substrate.

[0060] The drive unit 50 is a piezoelectric element such as a PZT element. However, the drive unit 50 is not limited to pressure elements such as PZT elements; it can be any configuration that can impart displacement to the ink based on a digital electrical signal.

[0061] As shown in Figure 4A, in this drive unit 50, multiple electrode layers 52 and 53 are inserted into the piezoelectric element. For example, electrode layer 52 is connected to GND, and electrode layer 53 is connected to a control unit that applies a voltage of 0 to 50V, thereby applying a voltage between electrode layer 52 and electrode layer 53.

[0062] When voltage is applied, the piezoelectric element expands and contracts in the Z direction, thus applying a compressive force to the ink in the +Z direction. Furthermore, by adjusting the applied voltage, the amount and speed of ink droplet ejection can be controlled. This function is called DPN (Drive Per Nozzle).

[0063] The drive unit 50 has a drive unit 54, a column 55, and a notch 56. The drive unit 54 and the column 55 are each sandwiched between two notches 56. The drive unit 54 is a piezoelectric element in which an electrode layer 53 is inserted and electrically connected to the control wiring 51 to which a voltage is applied, while the column 55 is a non-drive unit and is a piezoelectric element in which an electrode layer 52 is inserted and is not electrically connected to the control wiring 51 to which a voltage is not applied.

[0064] Furthermore, the pressure chamber 33 and nozzle 41, which consist of the vibrating plate 20, the flow path plate 30, and the nozzle plate 40, are arranged one at each position corresponding to the multiple drive units 54.

[0065] The drive unit 54 is driven by an electrical signal supplied from the control wiring 51. It is preferable that the control wiring 51 and the drive unit 50 are joined with an anisotropic conductive film (ACF) or the like. The notch 56 is formed by a dicing device or the like. The thickness of the dicing blade is, for example, 30 μm.

[0066] In this configuration, the drive units 54 and column units 55 are arranged alternately. By providing such column units 55, it is possible to mitigate a phenomenon called crosstalk that occurs when voltage is applied to adjacent drive units 54 simultaneously.

[0067] As shown in Figure 4B, the drive units 54 may be arranged continuously without providing the column section 55. In this case as well, the pressure chamber 33 and nozzle 41 are arranged one by one at the position corresponding to each of the multiple drive units 54, similar to the case in Figure 4A.

[0068] Figure 4C shows an example of a configuration when the control wiring 51 is a flexible printed circuit board. The flexible printed circuit board has a connection part 51a that is connected to the drive unit 50 and a connection part 51b that is connected to a control unit such as a control board. In the portion between the connection part 51a and the connection part 51b, a wiring pattern is formed on a flexibly deformable material such as polyimide.

[0069] Furthermore, as shown in the enlarged view of the connection portion 51a, the drive channel portion 57 connected to the drive body 50 has wiring formed in accordance with the arrangement of the drive unit 54, and each wire is connected to the electrode layer 53 of the drive unit 54. Similarly, multiple wires are formed in the GND portion 58 and are connected to the electrode layer 52 of the drive unit 54.

[0070] For example, it is preferable that the electrode layer 52 is electrically connected to the GND portion 58 via a GND electrode and ACF (Anisotropic Conducting Film) applied to the side or inside of the drive unit 50, and that the electrode layer 53 is electrically connected to the drive channel portion 57 via the ACF. However, the method of electrical connection with the GND portion 58 is not limited to this.

[0071] Next, the manufacturing method for the drive unit 54 will be explained. Figure 5A is a diagram illustrating the manufacturing method for the drive unit 54 when the column portion 55 is present, and Figure 5B is a diagram illustrating the manufacturing method for the drive unit 54 when the column portion 55 is absent.

[0072] As shown in Figure 5A, a drive unit 50 is formed in which drive units 54 and column units 55 are alternately arranged by forming notches with a dicing device or the like and selectively connecting them to control wiring 51 (not shown).

[0073] Furthermore, since the dicing blade 59 rotates and moves along the X direction to form a notch that penetrates the drive unit 50, the drive unit 54 and the column 55 are arranged along the Y direction.

[0074] For example, 100 to 800 drive units 54 are arranged along the Y direction, most of these drive units 54 are arranged at equal intervals with a pitch p, and at least some of them are arranged with a pitch p' different from pitch p.

[0075] Thus, the drive unit 50 has a row of drive units including a plurality of drive units 54 arranged on the same straight line with a pitch p at equal intervals, with some exceptions.

[0076] This configuration allows for higher print resolution in the direction perpendicular to the printing direction (Y' direction in Figure 1: sub-scanning direction) when using a line-head type inkjet head 100 that includes multiple drive units 54. Further details will be described later.

[0077] Furthermore, in the section where the pitch is p', it is desirable that the width of the column section 55 between the drive units 54 differs from the width of the other column sections 55. By doing so, it is possible to process sections with different pitches of the drive units 54 using the same dicing blade 59.

[0078] Furthermore, the parts of the drive unit 54 with different pitches may be formed by changing the thickness of the dicing blade 59 and changing the width of the notch while maintaining the same width for the column portion 55. By keeping the width of the column portion 55 the same, it is possible to prevent differences in the rigidity of the column portion 55.

[0079] Alternatively, as shown in Figure 5B, the column portion 55 may not be placed between the drive units 54, and the drive units 54 may be arranged continuously along the Y direction. In this case as well, for example, 100 to 800 channels of drive units 54 may be arranged along the Y direction, with most of these drive units 54 being arranged at equal intervals with a pitch p, and at least some of them being arranged with a pitch p' different from pitch p.

[0080] In this case as well, the drive unit 50 has a row of drive units 54 that are arranged in the same straight line with a pitch p at equal intervals, except for some.

[0081] In addition, for the portion with a pitch of p', the width of the drive unit 54 arranged at pitch p' may be configured to be different from that of the other drive units 54, similar to the case of the drive unit 50 having the column portion 55 shown in Figure 5A, or the drive unit 54 may be arranged at pitch p' by changing the thickness of the dicing blade 59 and changing the width of the notch.

[0082] Furthermore, although we have described the case in which the drive unit 54 is a stacked piezoelectric element comprising multiple electrode layers 52 and 53, the configuration of the drive unit 54 is not limited to this.

[0083] For example, the drive unit 54 may be a heating unit that heats the ink to expand and eject the ink, or it may be a configuration having a configuration called shear mode, or it may be a configuration using a thin-film PZT piezoelectric element.

[0084] In all configurations, the drive unit 54 plays the role of compressing the ink to eject it from the nozzle. In the following description, the drive unit 54 is defined as being at the point where it applies force to the ink, either directly or through other components interposed between the ink and the drive unit 54, to eject the ink from the nozzle 41.

[0085] Figure 6A is a diagram illustrating the drive unit 54 of the thermal jet system. In the thermal jet system, the ink 93 inside the pressure chamber 91 is compressed through the expansion force of bubbles generated by heat, thereby causing the ink 93 to be ejected from the nozzle 92. In other words, the point of force that compresses the ink 93 is the heat source that generates heat, and the heat source is the drive unit 54.

[0086] Figure 6B illustrates the drive unit 54 of the shear mode system. In the shear mode system, the piezoelectric element 94 deforms, compressing the ink 93 by sandwiching it from both sides, causing the ink 93 to be ejected from the nozzle. In this case, the midpoint of the line connecting the vertices of the deformed piezoelectric elements 94 is the drive unit 54. The ink 93 is ejected towards the front of the paper.

[0087] Figure 6C illustrates the drive unit 54 of the venting type. In the venting type, the apex of the deformed piezoelectric element 95 becomes the drive unit 54. The piezoelectric element 95 may be composed of a thin-film PZT element, or it may be composed of a bulk PZT element as in this embodiment.

[0088] Furthermore, it is desirable that the drive unit 54 be positioned at the center in the X direction relative to the pressure chamber 91. This is because uneven deflection of the drive unit 54 and the diaphragm 20 may lead to unstable discharge. On the other hand, in the Y direction, the drive unit 54 may be centered relative to the pressure chamber 91, or it may be offset from the center. The position of the drive unit 54 should be designed considering the balance with the position of the nozzle 92 and the pressure chamber 91.

[0089] Figure 6D illustrates time-division injection control for the share-mode drive unit 54. In this time-division injection control, two pairs of piezoelectric elements 94 corresponding to A, B, and C in Figure 6D sequentially sandwich and compress the ink from both sides, causing the ink 93 to be ejected from the nozzle.

[0090] Even in this case, the drive unit 54 still applies force to the ink either directly or through other components interposed between the ink and the drive unit 90, causing the ink to be ejected from the nozzle. Therefore, the drive unit 54 is present in all channels.

[0091] Next, the relationship between the inkjet head 100 and the drive units 110 and 111 will be explained using Figure 7. Figure 7 is a diagram illustrating the relationship between the inkjet head 100 and the drive units 110 and 111.

[0092] In this configuration, two drive units 110 and 111 are arranged for one inkjet head 100. Each of the drive units 110 and 111 contains approximately 600 drive units 54, most of which are arranged at a pitch p along the Y direction, and at least some of which are arranged at a pitch p'. Here, the drive units 54 arranged at pitch p' are located on the same straight line as the drive units 54 arranged at equal pitch p.

[0093] Specifically, the drive unit 110 has a drive unit row 115 in which approximately 300 drive units 54 are arranged at equal pitches p, and a drive unit row 116 in which approximately 300 drive units 54 are arranged at equal pitches p, both located on the same straight line.

[0094] The number of channels per drive unit 54 can be anything, such as 300ch, 450ch, 900ch, or 1200ch, and should be determined according to the desired head size and nozzle pitch.

[0095] Then, the pitch between the drive unit 54 located on the drive unit row 116 side of the drive unit row 115 and the drive unit 54 located on the drive unit row 115 side of the drive unit row 116 is p'.

[0096] The inkjet heads 100 configured in this way are arranged at an angle with respect to the printing direction (X' direction), and multiple rows of drive units are arranged parallel to each other at regular intervals, with the multiple inkjet heads 100 arranged along the Y' direction (sub-scanning direction) perpendicular to the X' direction.

[0097] Figure 8A is a diagram illustrating the arrangement method of the drive unit 54. Figure 8A is a view from the +Z direction of the drive body 110, in which the drive unit 54 and column portion 55 are formed by dicing piezoelectric elements.

[0098] As described above, most of the drive units 54 are arranged at equal pitches p with column sections 55 in between, and at least one location near the center of the movable body 110 is provided where drive units 54 are arranged at a pitch p' different from pitch p, with column sections 55 of different widths in between.

[0099] Figure 8B shows the positional relationship between the drive units 110 and 111 and the inkjet head 100. The inkjet head 100 has two drive units 110 and 111. The moving unit 110 has a drive unit 54 and a column 55, and the drive unit 111 has a drive unit 61 and a column 62.

[0100] It is preferable that the drive unit 110 and the drive unit 111 are arranged such that the center of one of the drive units 61 of the drive unit 111 lies on the perpendicular bisector of the line connecting the center of one of the drive units 54 of the drive unit 110 and the center of another drive unit 54 adjacent to that drive unit 54.

[0101] In this way, when multiple inkjet heads 100 are used individually rather than in parallel, most of the drive units 54 can be arranged at equal pitches perpendicular to the printing direction. Furthermore, the drive units 54 can be arranged along the Y direction at a pitch of p / 2. While the pitch is not equal in the portion where the pitch is p', this has a negligible practical effect.

[0102] Furthermore, line heads, which consist of multiple inkjet heads 100 arranged side-by-side, are often used for mass production of large-format panels. On the other hand, as a preliminary step to mass production, printing may be performed at low cost using a minimal configuration of inkjet heads 100, without worrying about equipment cycle time, for purposes such as performance verification and fine-tuning of printing process conditions. In addition, printing may be performed using small devices with a single or small number of inkjet heads 100.

[0103] For these reasons, the inkjet head 100 is generally used in a parallel configuration as shown in Figure 8D, but there are also advantages to using it individually.

[0104] Furthermore, when verifying printing performance using a single or a small number of inkjet heads 100, the reason why the influence of the p' portion of the pitch is practically negligible is explained below.

[0105] For example, when manufacturing a display panel using inkjet printing, it is important to droplet the ink onto the cells of the display panel. When manufacturing a high-resolution display panel, the control unit recognizes the cell position and the landing position of the ejection channel, and then printing is performed using the ejection channel whose coordinates match those of the cell and ejection channel.

[0106] In other words, it is not assumed that each ejection channel is arranged at equal pitches. Since the ejection position data for each ejection channel is generated each time printing is performed, even if the pitch p' is, for example, 4 / 5p, the practical impact is minimal. On the other hand, if the pitch p' is a large value such as 3p, the software executed by the control unit will not be able to compensate for it, resulting in areas where ink is not ejected and hindering the verification of printing performance.

[0107] Furthermore, when using the inkjet head 100 individually, the inkjet head 100 is often used in this configuration because the print width can be maximized when the longitudinal direction of the inkjet head 100 is parallel to the Y' direction and multiple drive units 54 are arranged in the Y' direction.

[0108] In contrast, to improve nozzle resolution, the inkjet head 100 may be positioned diagonally with respect to the printing direction. That is, depending on the cell pitch of the object to be printed, the inkjet head 100 may be rotated and aligned to match the nozzle pitch and cell pitch, and then positioned diagonally.

[0109] In either case, there are parts where the pitch is not equipick with respect to the p' portion, but for the reasons mentioned above, the practical effect is negligible.

[0110] Furthermore, considering factors such as printing inconsistencies and printing cycle time, it is desirable that in a mass production system for large-format panels, multiple inkjet heads are arranged side by side, the drive units 54 are arranged at equal pitches, and the printed dots are arranged at equal pitches in the Y' direction.

[0111] Figure 8C shows the case where the inkjet head 100 is positioned diagonally with respect to the printing direction. Figure 8D shows the case where multiple inkjet heads 100 are positioned in parallel.

[0112] By arranging multiple inkjet heads 100a to 100h, each having drive units 110a to 110h and 111a to 111h as shown in Figure 8C, in parallel and tilted with respect to the printing direction as shown in Figure 8D, a line head can be constructed. For reasons described later, the number of printed dots (dpi) in the direction perpendicular to the printing direction can be increased, thereby achieving high resolution.

[0113] Next, the relationship between the arrangement of the drive unit 54 and the print resolution will be explained. Figure 9A is a diagram illustrating the relationship between the arrangement of the drive unit 54 and the print resolution. The print resolution is the number of print dots (dpi) of the inkjet head 100 in the Y' direction in Figure 1.

[0114] Figure 9A shows drive units 110 and 111 having drive units 54 and 61 and column units 55 and 62, as well as straight lines α and β parallel to the Y-axis, and intersection points 130 to 133 of lines α and β and each drive unit 54 and 61. Here, the positions of intersection points 130 to 133 in the direction of lines α and β correspond to the positions of the center in the width direction of the drive units 54 and 61.

[0115] Intersections 130 and 131 are located on the line α at equal intervals p. If the shortest distance between intersections 130 and 131 is D, then the pitch p and the shortest distance D satisfy equation 1 below. D=(m+i / n)p (Formula 1)

[0116] Here, the constant m is a non-negative integer, the constant n is the value calculated by Equation 2 below, where a is the number of drive units 110 and 111 in the inkjet head 100, and b is the sum of the number of pitches p' different from the pitch p included in each drive unit 110 and 111, and the constant i is a natural number smaller than the constant n. The constant n will be explained in detail later. n=a×(b+1) (Formula 2)

[0117] Similarly, intersections 132 and 133 are aligned on the line β at equal intervals p. If the shortest distance between intersections 132 and 133 is D, then the shortest distance D satisfies equations 1 and 2 described above.

[0118] In the example shown in Figure 9A, the number of drive units 110 and 111, a, is 2, and the sum of the number of pitches p' different from the pitch p contained in each drive unit 110 and 111, b, is 1, so n = 2 × (1 + 1) = 4. Then, if m = 1 and i = 1, the shortest distance D is (5 / 4)p.

[0119] Here, Figure 9A is a conceptual diagram, but for example, the pitch p is 50 μm or more and 200 μm or less, the shortest distance D is 300 μm or less, the multiple drive unit rows of each inkjet head are arranged at an inclination angle of 45 degrees or more and 80 degrees or less with respect to the printing direction, and it is desirable that the number of inkjet heads is 20 or more and 120 or less.

[0120] Although not shown in Figure 9A, the protrusions 24 formed on the vibrating plate 20 shown in Figure 3, the pressure chambers 33 in the flow path plate 30, and the nozzles 41 provided on the nozzle plate 40 are all located on a straight line extending in the Z direction through the intersections 130 to 133, with one nozzle corresponding to each of the intersections 130 to 133. In other words, the straight line extending in the Z direction through the intersections 130 to 133 penetrates the protrusions 24, the pressure chambers 33, and a portion of the nozzles 41.

[0121] In particular, since the landing position of the ink ejected from the inkjet head 100 is basically determined by the position of the nozzle 41, the straight line extending in the Z direction through the intersection points 130-133 must penetrate a portion of the nozzle 41. On the other hand, the protrusion 24 and the pressure chamber 33 may not be penetrated depending on the configuration of the inkjet head 100.

[0122] Note that the straight line α and the straight line β only need to be on the drive body 110 and the drive body 111, respectively, and their positions in the X direction are arbitrary.

[0123] In other words, the nozzle 41 can be located anywhere in the X direction, and the drive unit 54 can also be located anywhere in the X direction, but the nozzle 41 and the drive unit 54 are located at the same position in the Y direction. Therefore, the lines α and β only need to pass through the position of the nozzle 41 at any position in the X direction, and will always pass through a part of the drive unit 54 that extends linearly in the X direction.

[0124] Next, we will explain the nozzle array for achieving high-resolution printing. Figure 9B is a diagram illustrating the nozzle array for achieving high-resolution printing.

[0125] Figure 9B shows nozzle rows a to h, which include nozzle 41, and the nozzles 41 included in each nozzle row a to h, as nozzles 130a to 133a and 130b to 133b. As described above, nozzles 130a to 133a and 130b to 133b are arranged on a straight line extending in the Z direction, passing through the intersection obtained as explained using Figure 9A.

[0126] In Figure 9A, the positions of intersections 130-133 were defined by two straight lines α and β and the widthwise centers of the drive units 54 and 61. However, in Figure 9B, the positions of the intersections are defined by four straight lines α-δ parallel to the Y-axis and the widthwise centers of the drive units.

[0127] As shown in Figure 9B, nozzles 130a and 131a are located on the same straight line α. Nozzles 132a and 133a are located on the same straight line β. Nozzles 130b and 131b are located on the same straight line γ. Nozzles 130b and 131b are located on the same straight line δ.

[0128] The nozzles 130a-133a and 130b-133b in each nozzle row a-h are arranged at equal pitches p.

[0129] Furthermore, if D is the shortest distance between a nozzle located on the nozzle row b side of nozzle row a and a nozzle located on the nozzle row a side of nozzle row b, then the shortest distance D satisfies equation 1 above. For example, when m=1, i=1, and n=4, D=(5 / 4)p.

[0130] Similarly, the shortest distance D between a nozzle located on the nozzle row d side of nozzle row c and a nozzle located on the nozzle row c side of nozzle row d, the shortest distance D between a nozzle located on the nozzle row f side of nozzle row e and a nozzle located on the nozzle row e side of nozzle row f, and the shortest distance D between a nozzle located on the nozzle row h side of nozzle row g and a nozzle located on the nozzle row g side of nozzle row h also satisfies Equation 1 above.

[0131] Next, we will explain the relationship between the positions of nozzles 130a, 130b, 131a, and 131b and the positions of nozzles 132a, 132b, 133a, and 133b. Nozzle 132a lies on a line ε that passes through the center point of the line connecting the positions of two adjacent nozzles 130a and extends in the X' direction. Also, nozzle 132a lies on the perpendicular bisector of the line connecting the positions of two adjacent nozzles 130a.

[0132] Similarly, nozzle 132b lies on a line ζ that passes through the center point of the line connecting the positions of two adjacent nozzles 130b and extends in the X' direction. Furthermore, nozzle 132b lies on the perpendicular bisector of the line connecting the positions of two adjacent nozzles 130b.

[0133] Furthermore, nozzle 133a lies on a straight line η that passes through the center point of the straight line connecting the positions of two adjacent nozzles 131a and extends in the X' direction. Also, nozzle 133a lies on the perpendicular bisector of the straight line connecting the positions of two adjacent nozzles 131a.

[0134] Similarly, nozzle 133b lies on a line θ that passes through the center point of the line connecting the positions of two adjacent nozzles 131b and extends in the X' direction. Furthermore, nozzle 133b lies on the perpendicular bisector of the line connecting the positions of two adjacent nozzles 131b.

[0135] As mentioned above, the fact that nozzles 132a, 132b, 133a, and 133b lie on the perpendicular bisector of the line connecting the positions of two adjacent nozzles 130a, 130b, 131a, and 131b has the effect of allowing the nozzle pitch in the Y' direction to be evenly distributed when the inkjet heads 100 are individually arranged parallel to the Y' direction.

[0136] However, in the case of an inkjet head 100 that is primarily intended to be used positioned diagonally with respect to the X' direction, the configuration may be such that nozzles 130a-133a and 130b-133b do not lie on the perpendicular bisector.

[0137] By arranging nozzles 130a-133a and 130b-133b in this manner, nozzles 130a-133a and 130b-133b can be formed alternately at equal pitch in the Y' direction. By ejecting ink from these nozzles, high-definition print dots 134 can be achieved, thereby increasing the print resolution.

[0138] Here, the printed dots 134 shown in Figure 9B indicate the intersection points of a straight line extending in the X' direction through nozzles 130a-133a and 130b-133b and an arbitrary straight line extending in the Y' direction. As can be seen from the printed dots 134, the printed dots corresponding to each nozzle 130a-133a and 130b-133b are formed sequentially at equal pitches.

[0139] Thus, as shown in Equation 1 above, by making the shortest distance D a non-integer multiple of the pitch p, and by making the spacing between multiple nozzles in the Y' direction perpendicular to the printing direction equal, the printing resolution can be increased.

[0140] The inkjet device 1 prints while moving the object to be printed 7 or the inkjet head 100 in the X' direction. In this process, the inkjet device 1 controls the printing timing based on encoder information from the transport table 4, so the positions of the nozzles 130a-133a and 130b-133b in the X' direction may be misaligned, but it is important that the nozzles 130a-133a and 130b-133b are arranged at equal and narrow pitches in the Y' direction.

[0141] Next, we will explain in more detail the aforementioned equations 1 and 2 relating to the shortest distance D. For the sake of simplicity, the following explanation will focus on the case where n=4.

[0142] (1) Regarding the constant i The constant i can be any natural number smaller than the constant n. When n=4, the constant i can be 1, 2, or 3. The shortest distance D is determined according to the value of the constant i.

[0143] When the constant i is set to 1 or 3, the distance between nozzle row a and nozzle row c should be determined such that the nozzle 132a included in nozzle row c lies on a straight line that passes through the center point of the straight line connecting adjacent nozzles 130a included in nozzle row a and extends in the X' direction, similar to the example shown in Figure 9B.

[0144] By doing so, nozzle 130a in nozzle row a and nozzle 132a in nozzle row c will be configured with a 1 / 2 phase difference. If the constant i is 1 or 3, then nozzles 130a and 131a in nozzle row a and nozzle row b, and nozzles 132a and 133a in nozzle row c and nozzle row d will be configured with a 1 / 4 phase difference, so that each row from nozzle row a to d can be configured with a 1 / 4 phase difference. The definition of phase in this embodiment will be described later.

[0145] The same applies to nozzle 133a in nozzle row d and its adjacent nozzle 131a in nozzle row b, nozzle 132b in nozzle row g and its adjacent nozzle 130b in nozzle row e, and nozzle 133b in nozzle row h and its adjacent nozzle 131b in nozzle row f.

[0146] Furthermore, if the constant i is set to 2, the distance between nozzle row a and nozzle row c should be determined such that the nozzle 132a included in nozzle row c lies on a straight line that extends in the X' direction, passing through points other than the center point, among the points obtained by dividing the straight line connecting adjacent nozzles 130a included in nozzle row a into four equal parts.

[0147] By doing so, nozzle 130a in nozzle row a and nozzle 132a in nozzle row c will be configured with a 1 / 4 phase shift. When the constant i is 2, each nozzle 130a and 131a in nozzle row a and nozzle row b, and each nozzle 132a and 133a in nozzle row c and nozzle row d will be configured with a 1 / 2 phase shift, so as a result, each row from nozzle row a to d can be configured with a 1 / 4 phase shift.

[0148] In this case as well, the same can be said for nozzle 133a in nozzle row d and adjacent nozzle 131a in nozzle row b, nozzle 132b in nozzle row g and adjacent nozzle 130b in nozzle row e, and nozzle 133b in nozzle row h and adjacent nozzle 131b in nozzle row f.

[0149] (2) Regarding pitch p The pitch p of nozzles 130a-133a and 130b-133b is, for example, between 50 μm and 200 μm. However, the pitch p can be set arbitrarily and should be determined appropriately according to the required printing resolution.

[0150] While reducing the pitch p can increase print resolution, doing so may worsen the crosstalk of the inkjet head 100. Therefore, the appropriate pitch p should be determined taking this into consideration.

[0151] (3) Regarding the constant m The constant m can be any integer greater than or equal to 0, but it is preferable that the constant m be 0 or 1. This is because minimizing the space where nozzles 130a~133a and 130b~133b do not exist increases the nozzle density in the inkjet head 100. When increasing the nozzle density, it is also possible to miniaturize the inkjet head 100 or reduce the nozzle arrangement width in the X' direction (i.e., the depth of the printing area in the line head), resulting in effects such as suppression of printing unevenness, miniaturization of the inkjet device 1, and cost reduction.

[0152] Furthermore, when using a single inkjet head 100 for the applications described above, the impact on printing performance due to the different pitches of nozzles 130a-133a and 130b-133b can be minimized.

[0153] Furthermore, when multiple drive units are arranged in a line, and multiple drive unit rows are provided on the same straight line for each drive unit, and ink is ejected from nozzle rows corresponding to each drive unit row, if the shortest distance D becomes long, for example, 3 to 10 mm, it becomes difficult to suppress printing unevenness, miniaturize the inkjet device 1, reduce costs, and utilize the inkjet device 1 with a single inkjet head 100.

[0154] In light of these considerations, it is desirable that the shortest distance D between multiple drive unit rows arranged on the same straight line be 300 μm or less. Furthermore, in order to achieve a shortest distance D of 300 μm or less, it is desirable that multiple drive units located directly above the multiple nozzles in the Z direction be provided on a single drive unit.

[0155] In other words, for example, multiple nozzle rows a to h are arranged in the positional relationship described using Figure 9B, and it is desirable that at least two of the multiple nozzle rows a to h that are arranged on the same straight line are configured to be given the force to eject ink by a single drive unit, that is, they are part of the same drive unit that gives displacement to the ink.

[0156] Here, the drive unit has multiple rows of drive units arranged on the same straight line, and each drive unit has drive units arranged at equal pitches p. In two adjacent rows of drive units, a first row and a second row, arranged on the same straight line, the drive units in the first row that are located on the second row side and the drive units in the second row that are located on the first row side are arranged at a pitch p' different from pitch p, and this pitch p' is equal to the shortest distance D calculated by Equation 1.

[0157] While a smaller minimum distance D is desirable, making it too small can lead to problems such as a decrease in machining accuracy and an increase in crosstalk.

[0158] In light of these considerations, it is desirable that the constant m is 0 or 1, and when the constant n is 4, the shortest distance D is between 3 / 4p and 5 / 4p. Also, when the constant n is 2, it is desirable that the shortest distance D is between 1 / 2p and 3 / 2p. In particular, when the constant m is 0, it is desirable that the constant i in the aforementioned equation 1 be the value obtained by subtracting 1 from the constant n, or the value obtained by adding 1 to the constant n.

[0159] (4) Regarding the constant n The constant n is determined using Equation 2, where a is the number of drive elements in the inkjet head 100 and b is the number of pitches p' that differ from pitch p in the drive elements. In other words, the constant n can be said to be the number of phases in the nozzle array of the inkjet head 100.

[0160] The number of phases in this nozzle array will be described using FIGS. 9C and 9D. FIG. 9C is a diagram showing four nozzle arrays a to d provided on a driving body when a plurality of inkjet heads 100 are arranged in parallel as shown in FIG. 8D. As shown in FIG. 9C, in each of the nozzle arrays a to d, each row is continuously formed without interruption in the Y' direction.

[0161] FIG. 9D is a diagram showing the positions of the nozzles in the Y' direction included in each of the nozzle arrays a to d. As shown in FIG. 9D, the nozzles included in the same nozzle arrays a to d are arranged at equal pitches in the Y' direction. Also, the nozzles included in each of the nozzle arrays a to d are arranged in the Y' direction in the order of the nozzles included in nozzle array c, the nozzles included in nozzle array b, the nozzles included in nozzle array a, and the nozzles included in nozzle array d. Note that the order of the nozzle arrays a to d in which the nozzles are arranged in the Y' direction varies depending on the value of the above-described constant i, the distance between the nozzle arrays a to d, etc., and is not limited to that shown in FIG. 9D and is arbitrary.

[0162] As described above, although the nozzles included in the same nozzle arrays a to d are continuously arranged at equal pitches in the Y' direction, a state where each nozzle included in the second nozzle array is arranged at the same position in the Y' direction with respect to each nozzle included in the first nozzle array is defined as a state where the second nozzle array is arranged in the same phase with respect to the first nozzle array.

[0163] Also, a state where the positions of each nozzle included in the second nozzle array are shifted by M / n (M is an integer satisfying M < n) of the nozzle pitch with respect to the positions of each nozzle included in the first nozzle array is defined as a state where the second nozzle array is arranged with a phase shift of M / n with respect to the first nozzle array.

[0164] For example, in the nozzle arrays shown in FIG. 9D, nozzle arrays b and d are arranged with a 1 / 4 phase shift with respect to nozzle array a, and nozzle array c is arranged with a 1 / 2 phase shift with respect to nozzle array a.

[0165] Here, since the number of nozzle rows with different phases among the multiple nozzle rows is 4, the constant n is 4 in the example shown in Figure 9D. Furthermore, since the drive unit is provided in a one-to-one correspondence with the nozzles, the constant n can also be said to be the number of drive unit rows with different phases among the multiple drive unit rows.

[0166] Furthermore, as shown in Figure 9C, each nozzle row a to d that forms a single phase must be formed continuously without interruption in the Y' direction. That is, the nozzles included in each nozzle row a to d must be arranged at equal pitches in the Y' direction.

[0167] Therefore, the steeper the angle of nozzle rows a to d, the narrower the nozzle spacing in the Y' direction becomes, which allows for the realization of a high-resolution line head. However, if the angle of nozzle rows a to d is made steeper, in order to form nozzle rows a to d continuously without interruption in the Y' direction, it is necessary to either lengthen the rows of nozzle rows a to d as shown in Figure 9c, or narrow the width of each nozzle row a to d.

[0168] The width of nozzle rows a to d is limited by factors such as the width of the inkjet head 100, so there is a limit to how narrow it can be made. Basically, it is necessary to increase the row length, but this may lead to an expansion of the size and print width of the inkjet head 100.

[0169] In contrast, by using the configuration described in this embodiment, even if the nozzle rows a to d become longer in order to make the angle of the nozzle rows a to d steeper, the space in the Y direction where no nozzles exist can be reduced, and the four nozzle rows a to d can be effectively arranged sequentially at equal pitches in the Y' direction. This makes it possible to achieve both improved nozzle resolution and miniaturization of the inkjet head 100.

[0170] Note that while Figures 9C and 9D illustrate the nozzle arrangement of one inkjet head 100 with a phase count of 4, any phase count of 2 or more is acceptable. The phase count of one inkjet head 100 is determined by the product of the phase count of one drive unit and the number of drive units, but the setting of these values ​​is arbitrary.

[0171] (First variation) Next, we will describe a modified configuration of the drive unit and drive unit array. Figure 10A shows a first modified configuration of the drive unit and drive unit array.

[0172] In this configuration, each inkjet head 100a to 100d has one drive unit 110a to 110d, and each drive unit 110a to 110d has two drive unit rows 115a to 115d and 116a to 116d, resulting in a phase count of 2.

[0173] This configuration allows for a reduction in the width of the inkjet heads 100a to 100d. Furthermore, because the width within the same nozzle row can be reduced, it becomes possible to keep the length of the nozzle row shorter even when making the slope of the nozzle row steeper.

[0174] (Second variation) A single inkjet head 100 may have three or more drive units. Figure 10B shows a second modified example of the configuration of the drive units and drive unit array.

[0175] In this configuration, each inkjet head 100a to 100c has three drive units 110a to 112a, 110b to 112b, and 110c to 112c, and each drive unit 110a to 112a, 110b to 112b, and 110c to 112c has two drive unit rows 115a to 115c and 116a to 116c, resulting in a total of 6 phases.

[0176] In this configuration, the number of phases increases, so if the pitch of the nozzles in each nozzle row is p, it becomes possible to position the nozzles in each nozzle row by shifting their position by p / 6 in the Y' direction.

[0177] Furthermore, in order to arrange the nozzles at a continuous, equal pitch in the Y' direction, it is necessary to increase the longitudinal length of the inkjet heads 100a to 100c and their drive units 110a to 112a, 110b to 112b, and 110c to 112c, or to make the inclination of the inkjet heads 100a to 100c obtuse.

[0178] In particular, there are manufacturing constraints on the longitudinal length of the inkjet head 100 and its drive units 110a-112a, 110b-112b, and 110c-112c, but if these constraints are met, the nozzle arrangement can be made more dense in the Y' direction.

[0179] (Third variation) The inkjet head may be configured such that the number of phases is 3 or more with a single drive unit. Figure 10C shows a third modified example of the configuration of the drive unit and drive unit array.

[0180] In this configuration, each inkjet head 100a to 100c has two drive units 110a to 110c and 111a to 111c, and each drive unit 110a to 110c and 111a to 111c has three drive unit rows 115a to 120a, 115b to 120b, and 115c to 120c arranged in the same straight line, resulting in a total of 6 phases.

[0181] In this configuration as well, the number of phases increases, so if the pitch of the nozzles in each nozzle row is p, it becomes possible to position the nozzles in each nozzle row by shifting their position by p / 6 in the Y' direction.

[0182] Furthermore, similar to the second modification, in order to arrange the nozzles continuously at equal pitch in the Y' direction, it is necessary to increase the longitudinal length of the inkjet heads 100a to 100c and their drive units 110a to 110c, 111a to 111c, or to make the inclination of the inkjet heads 100a to 100c obtuse. However, if the aforementioned constraints are met, the nozzle arrangement in the Y' direction can be made denser.

[0183] (Fourth variation) A single drive unit may have multiple drive unit rows in the X direction. Figure 10D shows a fourth modified example of the configuration of the drive unit and drive unit rows.

[0184] In this configuration, each inkjet head 100a, 100b has two drive units 110a, 111a, 110b, 111b, and each drive unit 110a, 111a, 110b, 111b has four drive unit rows 115a~118a, 115b~118b, 115c~118c, 115d~118d, resulting in a phase count of 4 in one drive unit 110a, 111a, 110b, 111b, and a phase count of 8 in each inkjet head 100a, 100b.

[0185] Here, the four drive unit rows 115a-118a, 115b-118b, 115c-118c, and 115d-118d of each drive unit 110a, 111a, 110b, and 111b are arranged in pairs on the same straight line to form a first drive unit row and a second drive unit row, with the second drive unit row being located in a position where the first drive unit row is shifted parallel in the X direction.

[0186] Even with this configuration, high-resolution printing is possible while simultaneously achieving miniaturization of the inkjet head 100 and a reduction in the depth of the line head's printing area.

[0187] Figure 10E shows an example of a nozzle array when a single drive unit has multiple drive unit rows in the X direction, as shown in the inkjet heads 100a and 100b in Figure 10D.

[0188] Figure 10E shows the inkjet heads 100a and 100b, along with the common circulation channels 140a to 140c. It also shows that the inkjet heads 100a and 100b have individual circulation channels 141a and 141b, pressure chambers 142a and 142b, and nozzles 143a and 143b.

[0189] Ink flows into pressure chambers 142a and 142b from an ink supply path (not shown) and is discharged from nozzles 143a and 143b. Ink that is not discharged from nozzles 143a and 143b flows into common circulation paths 140a to 140c via individual circulation paths 141a and 141b.

[0190] In this configuration, it is difficult to narrow the nozzle row pitch p, requiring approximately twice the pitch in the X direction compared to the case where there is only one nozzle row, thus reducing the effect of increasing the nozzle density in the Y' direction. However, due to reasons such as the ease of increasing the upper area of ​​the pressure chambers 142a and 142b, the ejection performance of the inkjet heads 100a and 100b can be improved.

[0191] Even in this configuration, by arranging the drive units included in the drive unit row at equal pitches p within a single drive unit, and arranging at least one drive unit at a different pitch p', it is possible to increase the nozzle density in the Y' direction while maintaining miniaturization of the inkjet heads 100a and 100b.

[0192] (Fifth variation) When a single drive unit has multiple drive unit rows in the X direction, in the example shown in Figure 10D, the phases of the multiple drive unit rows are different, but the phases of the multiple drive unit rows may be the same. Figure 10F shows a fifth modified example of the configuration of the drive unit and drive unit rows.

[0193] In this configuration, the inkjet head 100 has two drive units 110 and 111, and each drive unit 110 and 111 has two drive unit rows 115a to 118a and 115b to 118b arranged in the same straight line. In this case, the number of phases in one drive unit 110 or 111 is 2, and the number of phases in one inkjet head 100 is 4.

[0194] Even with this configuration, it is possible to achieve the same effects as the configuration shown in Figure 7, such as miniaturizing the inkjet head 100 and shortening the depth of the printing area of ​​the line head, while enabling high-definition printing. Furthermore, as in the case of Figure 10E, the ejection performance of the inkjet head 100 can be improved because it is easier to increase the upper area of ​​the pressure chamber.

[0195] (Sixth variation) When a single drive unit has multiple drive unit rows in the X direction, in the example shown in Figure 10D, the phases of the multiple drive unit rows are different, but the phases of the multiple drive unit rows may be the same. Figure 10G shows a sixth modified example of the configuration of the drive unit and drive unit rows.

[0196] In this configuration, the inkjet head 100 has one drive unit 110, and the drive unit 110 has two drive unit rows 115 to 118 arranged in the same straight line. Furthermore, drive unit row 115 and drive unit row 117 are in the same phase, and drive unit row 116 and drive unit row 118 are in the same phase. In other words, in this case, the number of phases is 2.

[0197] (Inkjet head manufacturing process) In manufacturing the inkjet head 100 of this embodiment, it is necessary to use relatively long drive units compared to cases where multiple drive units are arranged in the same straight line. Furthermore, when heat-bonding the drive unit 50 shown in Figure 2 with other components such as the vibrating plate 20 and flow path plate 30 that constitute the pressure chamber for storing ink, delamination due to differences in thermal expansion coefficients may become a problem.

[0198] Therefore, it is desirable to use a low-temperature thermosetting adhesive that cures at a relatively low heating temperature, for example, below 70 degrees Celsius, for heat bonding. In practice, a low-temperature thermosetting adhesive that cures at 60 degrees Celsius is used to bond the vibration plate 20, the flow path plate 30, and the nozzle plate 40 to the drive unit 50, which are then joined together as a single integrated component.

[0199] Furthermore, when using a relatively long drive unit 50, warping of the drive unit 50 itself may also become a problem. Figure 11 illustrates a method for dealing with warping of the drive unit 50 itself.

[0200] As shown in Figure 11, in order to address the warping of the drive unit 50 itself, it is desirable to insert electrode layers 52 and 53 near the center of the drive unit 50, and to also insert dummy electrode layers 150a and 150b separately near the upper and lower end faces of the drive unit 50, away from the center. The inserted dummy electrode layers 150a and 150b may be processed and removed in a pre-joining process with other components, or they may be used as GND electrode layers.

[0201] Furthermore, the manufacturing method of the nozzle also requires ingenuity. For example, when processing nozzles with a laser, a method is often used in which multiple nozzles are formed simultaneously using a diffraction grating element called a DOE (Diffractive Optical Element).

[0202] In that case, if processing is performed sequentially from the longitudinal end of the inkjet head 100, it becomes difficult to process parts that have a pitch p' different from the pitch p of the drive unit. Therefore, for example, when processing a second nozzle row on the same line as a first nozzle row, it is desirable to process the nozzles in order from the nozzles closest to the first nozzle row.

[0203] Furthermore, the configuration of the flow path section that allows ink to flow into or out of the inkjet head 100 should also be designed to ensure an effective arrangement of the nozzles and drive unit.

[0204] Specifically, it is desirable to minimize the number of fittings for supplying or draining ink to the inkjet head 100. In practice, it is desirable to have only one fitting each for supplying ink to the inkjet head 100 and for draining ink from the inkjet head 100, and for each fitting to be located on the outside of all drive unit rows.

[0205] For example, these joints are positioned in the Y-direction at a location where the Y-coordinate is greater than the Y-coordinate value of all the drive units combined, or at a location where the Y-coordinate is smaller than the Y-coordinate value of all the drive units combined.

[0206] As described above, the inkjet head configuration described in this embodiment comprises a plurality of drive unit rows arranged at a pitch p, and a plurality of nozzles positioned at positions corresponding to each drive unit, which eject ink by the drive of the drive unit. The plurality of drive unit rows include a first drive unit row and a second drive unit row arranged on the same straight line, and the shortest distance D between a drive unit located on the second drive unit row side of the first drive unit row and a drive unit located on the first drive unit row side of the second drive unit row is a non-integer multiple of the pitch p.

[0207] This makes it possible to achieve a high-resolution line head, such as 2,400 dpi, when multiple inkjet heads 100 are arranged diagonally with respect to the printing direction to form a line head.

[0208] Furthermore, even when used at resolutions such as 600-1,200 dpi, the drive unit and nozzles can be effectively arranged, reducing the number of inkjet heads used and making the tilt angle less obtuse, thereby achieving cost reduction and a reduction in printing inconsistencies. [Industrial applicability]

[0209] This disclosure is applicable to inkjet heads, line heads, inkjet devices, and methods for manufacturing inkjet heads. [Explanation of Symbols]

[0210] 1. Inkjet device 2 bases 3 Guide 4. Transport Table 5 Gantries 6 head units 7. Printable object 8. Drive system 10 Housing section 20 Vibration Plate 30 Flow Plates 40 Nozzle Plates 50, 110, 111 drive unit 54 Drive unit 55 Column section 60 Base 70 and 80 FPC section 100 inkjet heads 115, 116, 117, 118 Drive unit row

Claims

1. Multiple rows of drive units arranged at a pitch p, A plurality of nozzles are arranged at positions corresponding to each of the aforementioned drive units, and which eject ink when driven by the drive units, Equipped with, The plurality of drive unit rows include a first drive unit row and a second drive unit row arranged on the same straight line, and the shortest distance D between a drive unit included in the first drive unit row that is located on the side of the second drive unit row and a drive unit included in the second drive unit row that is located on the side of the first drive unit row is a non-integer multiple of the pitch p. Inkjet head.

2. The inkjet head according to claim 1, wherein the first drive unit row and the second drive unit row are part of the same drive unit that provides displacement to the ink.

3. The inkjet head according to claim 1, wherein the shortest distance D is an integer multiple of the value obtained by dividing the pitch p by a constant n, and the constant n is the number of drive unit rows having different phases among the plurality of drive unit rows.

4. The inkjet head according to claim 1, wherein the shortest distance D is (m + i / n)p, where m is a non-negative integer, n is the number of drive unit rows having different phases among the plurality of drive unit rows, and i is a natural number smaller than the constant n.

5. The inkjet head according to claim 1, wherein the plurality of drive unit rows include a third drive unit row and a fourth drive unit row arranged on the same straight line parallel to the same straight line, the first drive unit row and the second drive unit row are part of a first drive body, the third drive unit row and the fourth drive unit row are part of a second drive body different from the first drive body, the number of phases in the first drive body and the second drive body are each 2, and the total number of phases is 4.

6. The inkjet head according to claim 4, wherein the constant m is 0, and the constant i is the value obtained by subtracting 1 from the constant n, or the value obtained by adding 1 to the constant n.

7. The inkjet head according to claim 1, wherein, among two adjacent parallel rows of drive units included in the plurality of drive unit rows, the drive unit included in the first drive unit row of one drive unit row is located on the perpendicular bisector of the line connecting the adjacent drive unit included in the first drive unit row of the other drive unit row, and the drive unit included in the second drive unit row of the one drive unit row is located on the perpendicular bisector of the line connecting the adjacent drive unit included in the second drive unit row of the other drive unit row.

8. The inkjet head according to claim 1, wherein the plurality of drive units are provided with non-drive units between adjacent drive units, the drive units are piezoelectric elements with electrode layers to which voltage is applied, and the non-drive units are piezoelectric elements with electrode layers to which voltage is not applied.

9. A line head comprising a plurality of inkjet heads as described in claim 1.

10. The line head according to claim 9, wherein the pitch p is 50 μm or more and 200 μm or less, the shortest distance D is 300 μm or less, the plurality of drive unit rows are arranged at an inclination angle of 45° or more and 80° or less with respect to the printing direction, and the number of inkjet heads is 20 or more and 120 or less.

11. The line head according to claim 9, A transport table on which the object to be printed, to be coated with the aforementioned ink, A drive device for moving the line head and the transport table relative to each other, An inkjet device equipped with the following features.

12. The drive unit and the member constituting the pressure chamber for storing the ink are joined together with a thermosetting adhesive that hardens at a temperature of 70 degrees Celsius or less in between. The aforementioned thermosetting adhesive is heat-cured at a temperature of 70 degrees Celsius or lower. A method for manufacturing an inkjet head according to claim 1.

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