Liquid ejection device and head module

Abstract

To increase moving speed in a main scanning direction of a head module without widening an interval of dots.SOLUTION: A head module in which a first direction is a main scanning direction includes a first nozzle array including first nozzles for discharging a liquid, a second nozzle array including second nozzles for discharging a liquid, and a third nozzle array including third nozzles for discharging a liquid, wherein an interval P1 between the first nozzle array and the second nozzle array in the first direction and an interval P2 between the first nozzle array and the third nozzle array in the first direction can be represented as P1:P2=E1:O1 by a value E1 that is a positive even number and a value O1 that is a positive odd number satisfying O1>E1.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a liquid ejection device and a head module.

Background Art

[0002] A liquid ejection device including a head module that forms dots on a medium by ejecting a liquid, such as an inkjet printer, is widely known. For example, Patent Document 1 describes a liquid ejection device including a head module provided with a nozzle row composed of a plurality of nozzles that eject a liquid, and a carriage that reciprocates the head module in a main scanning direction with respect to the medium.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, with the demand for speeding up the process of forming dots in a liquid ejection device, speeding up the relative movement speed of the head module with respect to the medium in the main scanning direction has been required. However, when the relative movement speed of the head module with respect to the medium in the main scanning direction is increased, there is a problem that the dot interval in the main scanning direction becomes wider.

Means for Solving the Problems

[0005] One aspect of the head module according to the present invention is a head module having a first direction as a main scanning direction, including a first nozzle row including a first nozzle for discharging a liquid, a second nozzle row including a second nozzle for discharging a liquid, and a third nozzle row including a third nozzle for discharging a liquid, wherein the distance P1 between the first nozzle row and the second nozzle row in the first direction and the distance P2 between the first nozzle row and the third nozzle row in the first direction can be expressed as P1:P2 = E1:O1, where E1 is a positive even number and O1 is a positive odd number satisfying O1>E1.

[0006] One aspect of the head module according to the present invention is a head module having a first direction as a main scanning direction, including a first nozzle row including a first nozzle for discharging a liquid, a second nozzle row including a second nozzle for discharging a liquid, and a third nozzle row including a third nozzle for discharging a liquid, wherein the distance P1 between the first nozzle row and the second nozzle row in the first direction and the distance P2 between the first nozzle row and the third nozzle row in the first direction can be expressed as P1:P2 = M×α:M×β + 1, where M is a natural number of 3 or more, α is a natural number of 1 or more, and β is a natural number satisfying β>α.

[0007] One aspect of the head module according to the present invention is a head module having a first direction as a main scanning direction, including a first nozzle row including nozzles for discharging liquid, a second nozzle row including nozzles for discharging liquid, and (M - 1) specific nozzle rows including nozzles for discharging liquid. When a value m is a natural number satisfying 1 ≦ m ≦ M - 1, the interval P1 between the first nozzle row and the second nozzle row in the first direction, and the interval PT[m] between the first nozzle row and the m-th specific nozzle row among the (M - 1) specific nozzle rows in the first direction are such that the value M, the value α, a value βT[m] which is a natural number satisfying βT[m]>α, a value m1 is a natural number satisfying 1 ≦ m1 ≦ M - 1, a value m2 is a natural number satisfying 1 ≦ m2 ≦ M - 1 and m1≠m2, and a value γT[m] which is a natural number satisfying 0<γT[m]≦M - 1 and γT[m1]≠γT[m2], P1:PT[m]=M×α:M×βT[m]+γT[m] can be expressed, which is characterized.

[0008] One aspect of the head module according to the present invention is a head module having a first direction as a main scanning direction, including a first nozzle for discharging liquid, a second nozzle for discharging liquid, and a third nozzle for discharging liquid. The interval in the first direction between a first dot formed by the liquid discharged by the first nozzle at a first timing and a second dot formed by the liquid discharged by the first nozzle at a second timing when the first nozzle can first discharge liquid after the first timing is defined as an interval D1. The interval in the first direction between a third dot formed by the liquid discharged by the second nozzle at the first timing and the first dot is defined as an interval D2. The interval in the first direction between a fourth dot formed by the liquid discharged by the third nozzle at the first timing and the first dot is defined as an interval D3. The first nozzle, the second nozzle, and the third nozzle are provided such that the interval D2 is an integral multiple of the interval D1 and the interval D3 is an interval different from an integral multiple of the interval D1, which is characterized.

Brief Description of Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Note that the dimensions and scales of each part in the drawings may be different from the actual ones, and there are also parts schematically shown for easy understanding. Further, the scope of the present invention is not limited to these embodiments unless otherwise specifically stated in the following description.

[0011] 1. First Embodiment In the first embodiment, an inkjet printer that ejects ink to form an image on a recording paper PE will be exemplified to describe a liquid ejection device. Note that in this embodiment, ink is an example of "liquid", and recording paper PE is an example of "medium".

[0012] 1.1. Outline of Inkjet Printer With reference to FIG. 1, the outline of the inkjet printer 1 according to the first embodiment will be described. Here, FIG. 1 is a perspective view showing an example of the schematic internal structure of the inkjet printer 1 according to the first embodiment.

[0013] Print data Img indicating an image to be formed by the inkjet printer 1 is supplied to the inkjet printer 1 from a host computer such as a personal computer or a digital camera. The inkjet printer 1 executes a printing process of forming the image indicated by the print data Img supplied from the host computer on the recording paper PE.

[0014] As exemplified in FIG. 1, in the first embodiment, it is assumed that the inkjet printer 1 is a serial printer. Specifically, the inkjet printer 1 moves the head module 2 in the main scanning direction and ejects ink from nozzles N provided in a head chip 3 (not shown) of the head module 2 to execute the printing process. Further, the inkjet printer 1 conveys the recording paper PE in the sub-scanning direction. Hereinafter, as shown in FIG. 1, the +X direction and the -X direction opposite to the +X direction are collectively referred to as the "X-axis direction". The X-axis direction is an example of the "main scanning direction" in the first embodiment. Also, the +Y direction orthogonal to the X-axis direction and the -Y direction opposite to the +Y direction are collectively referred to as the "Y-axis direction". The Y-axis direction is an example of the "sub-scanning direction" in the first embodiment. Further, the +Z direction orthogonal to the +X direction and the +Y direction and the -Z direction opposite to the +Z direction are collectively referred to as the "Z-axis direction". Note that the description of the head chip 3 and the nozzles N will be given later.

[0015] As illustrated in FIG. 1, an inkjet printer 1 according to the first embodiment includes a housing 10, a head module 2 including a head chip 3 provided with a plurality of nozzles N for ejecting ink, and a conveyance mechanism 7 for changing the relative position of a recording sheet PE with respect to the head module 2. When printing processing is executed, the conveyance mechanism 7 can reciprocate in the X-axis direction within the housing 10 to drive a carriage 761 on which the head module 2 is mounted, and conveys the recording sheet PE in the sub-scanning direction (specifically, at least one direction of the +Y direction and the -Y direction), thereby changing the relative position of the recording sheet PE with respect to the head module 2 and enabling ink to land on the entire recording sheet PE. Specifically, the conveyance mechanism 7 includes the aforementioned carriage 761, a conveyance motor (not shown) that serves as a drive source for reciprocating the carriage 761 in the X-axis direction, a paper feed motor 73 that serves as a drive source for conveying the recording sheet PE in the +Y direction, a carriage guide shaft 74 extending in the X-axis direction, a pulley 711 that is rotationally driven by the conveyance motor, a rotatable pulley 712, and a timing belt 710 that is stretched between the pulley 711 and the pulley 712 and extends in the X-axis direction. The carriage 761 is supported by the carriage guide shaft 74 so as to be reciprocable in the X-axis direction and is fixed to a predetermined position of the timing belt 710 via a fixture 762. Therefore, the conveyance mechanism 7 can move the carriage 761 and the head module 2 mounted on the carriage 761 along the carriage guide shaft 74 in the X-axis direction by rotationally driving the pulley 711 with the conveyance motor.

[0016] Further, the transport mechanism 7 includes a platen 75 provided below the carriage 761, that is, in the +Z direction of the carriage 761, a paper feed roller (not shown) that rotates in response to the drive of the paper feed motor 73 and supplies the recording paper PE one by one onto the platen 75, and a paper discharge roller 730 that rotates in response to the drive of the paper feed motor 73 and transports the recording paper PE on the platen 75 to the paper discharge port. Therefore, as shown in FIG. 1, the transport mechanism 7 can transport the recording paper PE on the platen 75 from the upstream -Y direction to the downstream +Y direction.

[0017] In the first embodiment, as illustrated in FIG. 1, one ink cartridge 4 is stored in the carriage 761 of the inkjet printer 1. The ink cartridge 4 is filled with single - color ink and is an example of a liquid storage portion. Note that FIG. 1 is merely an example, and the ink cartridge 4 may be provided outside the carriage 761. Also, a plurality of ink cartridges 4 filled with different - colored inks may be stored in the carriage 761. For example, four ink cartridges 4 corresponding to cyan, magenta, yellow, and black inks may be stored in the carriage 761. Further, instead of the ink cartridge 4, an ink pack composed of a flexible bag or an ink tank provided with an injection port for replenishing ink from an ink bottle may be adopted as the liquid storage portion.

[0018] As illustrated in FIG. 1, the inkjet printer 1 includes a control unit 8. The control unit 8 includes a storage unit that stores various information such as the control program of the inkjet printer 1 and print data Img supplied from a host computer, a CPU (Central Processing Unit), and other various circuits. Note that the control unit 8 may include a programmable logic device such as an FPGA (field - programmable gate array) instead of the CPU. As illustrated in FIG. 1, the control unit 8 is provided outside the carriage 761. Then, the control unit 8 and the head module 2 are electrically connected by the cable CB illustrated in FIG. 1. In the first embodiment, a flexible flat cable is adopted as the cable CB.

[0019] The control unit 8 controls the operations of the respective parts of the inkjet printer 1 by the CPU operating according to the control program stored in the storage unit. For example, the control unit 8 controls the operations of the head module 2 and the conveyance mechanism 7 so that a printing process for forming an image corresponding to the print data Img on the recording paper PE is executed. Specifically, the control unit 8 supplies the drive signal Com and the print signal SI to the head module 2. Here, the drive signal Com is a signal for discharging ink from the nozzle N by driving the piezoelectric element provided corresponding to the nozzle N. In the present embodiment, the control unit 8 can supply a common drive signal Com to a plurality of piezoelectric elements provided corresponding to the plurality of nozzles N included in the head module 2. Further, the print signal SI is a signal for designating whether to supply the drive signal Com to each piezoelectric element. That is, in the present embodiment, if the print signal SI designates to supply the drive signal Com to all of the plurality of piezoelectric elements provided corresponding to the plurality of nozzles N included in the head module 2, the control unit 8 supplies the common drive signal Com to all of the piezoelectric elements provided in the head module 2. In other words, in the present embodiment, if the print signal SI designates to supply the drive signal Com to all of the plurality of piezoelectric elements provided corresponding to the plurality of nozzles N included in the head module 2, the control unit 8 supplies the drive signal Com having the same waveform of the same shape to all of the piezoelectric elements provided in the head module 2 at the same timing. In the present embodiment, the plurality of piezoelectric elements provided in the head module 2 includes a plurality of piezoelectric elements 331 and a plurality of piezoelectric elements 332. The description of the piezoelectric element 331 and the piezoelectric element 332 will be described later.

[0020] 1.2. Overview of the head module FIG. 2 is a cross-sectional view of the head module 2 in the present embodiment. The head module 2 in the present embodiment includes an ink introduction member 22, a circuit board 24, an intermediate flow path member 23, a head chip 3, a holder 25, a fixing plate 26, and the like. Hereinafter, among the surfaces perpendicular to the Z-axis direction of each member, the surface on the -Z direction side may be referred to as the upper surface, and the surface on the +Z direction side may be referred to as the lower surface.

[0021] An ink introduction needle 21 is provided on the upper surface of the ink introduction member 22. Both the ink introduction member 22 and the ink introduction needle 21 are made of synthetic resin. A filter 213 is provided between the ink introduction needle 21 and the ink introduction member 22. The filter 213 is a member that filters the ink introduced from the ink introduction needle 21. For example, a member in which metal is woven in a mesh shape or a thin metal plate with a large number of holes is used. Foreign matters and bubbles in the ink are captured by the filter 213. In the present embodiment, an ink cartridge 4 is mounted on the upper surface of the ink introduction member 22, and the ink introduction needle 21 is inserted into the ink cartridge 4. The ink in the ink cartridge 4 is introduced from the needle hole 211 provided at the tip of the ink introduction needle 21 into the needle flow path 212. The ink introduced from the ink introduction needle 21 passes through the filter 213 and is supplied from the introduction port 220 into the head module 2. Thereafter, the ink passes through the distribution flow path 221 and is supplied to the intermediate flow path member 23 disposed on the +Z direction side of the ink introduction member 22.

[0022] An intermediate flow path member 23 is formed with an intermediate flow path 232 to which ink is supplied from a distribution flow path 221. Further, a cylindrical flow path connection portion 231 is provided on the upper surface of the intermediate flow path member 23. The height of the flow path connection portion 231 in the Z-axis direction is equal to or greater than the thickness of a circuit board 24 disposed between the ink introduction member 22 and the intermediate flow path member 23. The flow path connection portion 231 introduces the ink supplied from the distribution flow path 221 of the ink introduction member 22 into the intermediate flow path 232. The intermediate flow path 232 communicates with a supply flow path 251 provided in a holder 25. Further, the intermediate flow path member 23 is provided with an opening 233 at a position different from the intermediate flow path 232 when viewed in the +Z direction. The opening 233 communicates with an opening 242 provided in the circuit board 24 and also communicates with an opening 252 provided in the holder 25. A wiring board 30 provided with a drive circuit 300 is inserted through the opening 233.

[0023] The circuit board 24 is disposed between the ink introduction member 22 and the intermediate flow path member 23. The circuit board 24 is a printed board on which a wiring pattern for supplying a drive signal Com and a print signal SI supplied from a control unit 8 of the inkjet printer 1 to the wiring board 30 is formed. On the upper surface of the circuit board 24, a board terminal 243 connected to the wiring board 30 is formed. Further, on at least one of the upper surface or the lower surface of the circuit board 24, a connector 249 (not shown) to which a cable CB for supplying the drive signal Com and the print signal SI from the control unit 8 is connected is mounted.

[0024] The circuit board 24 is provided with an opening 241 through which the flow path connection portion 231 is inserted. The opening 241 is a through hole larger than the outer diameter of the flow path connection portion 231. Further, the circuit board 24 is provided with an opening 242 through which the wiring board 30 is inserted.

[0025] The holder 25 is provided with a plurality of lower recesses 254. The lower recesses 254 are concave spaces opening toward the +Z direction side. The lower recesses 254 house and hold a head chip 3 fixed to a fixing plate 26. The fixing plate 26 is composed of, for example, a metal plate material such as stainless steel. Further, the holder 25 is provided with an upper recess 253. The upper recess 253 is a concave space that opens toward the -Z direction side. The intermediate flow path member 23 and the circuit board 24 are accommodated in the upper recess 253. Also, as described above, the holder 25 is provided with a supply flow path 251. The supply flow path 251 communicates with the supply ports 311 and 312 provided in the head chip 3 accommodated in the lower recess 254. Thereby, the ink introduced from the ink cartridge 4 through the ink introduction needle 21 is filtered by the filter 213 and then supplied from the supply ports 311 and 312 to the head chip 3 through the distribution flow path 221, the intermediate flow path 232, and the supply flow path 251. In the first embodiment, since the head module 2 includes one ink introduction needle 21, the ink supplied to each of the plurality of head chips 3 is of the same type, and the ink supplied to each of the nozzles N provided in each of the head chips 3 is of the same type. That is, all the nozzles provided in the head module 2 eject the same type of ink.

[0026] Also, as shown in FIG. 2, the plurality of head chips 3 are arranged to be aligned along the X-axis direction. Specifically, from the -X direction to the +X direction, the head chips 3[1], 3[2], 3[3], and 3[4] are fixed to a plurality of lower recesses 254 provided in the holder 25 in this order. Note that when not distinguishing between the head chips 3[1] to 3[4], they are simply referred to as the head chip 3. Also, the head chip 3[1] includes the nozzle plate C[1], the head chip 3[2] includes the nozzle plate C[2], the head chip 3[3] includes the nozzle plate C[3], and the head chip 3[4] includes the nozzle plate C[4]. Also, in the +Z direction, the nozzle plate C[1] is exposed from the plate opening W[1] provided in the fixing plate 26, the nozzle plate C[2] is exposed from the plate opening W[2] provided in the fixing plate 26, the nozzle plate C[3] is exposed from the plate opening W[3] provided in the fixing plate 26, and the nozzle plate C[4] is exposed from the plate opening W[4] provided in the fixing plate 26. Note that the plurality of plate openings W are provided in the fixing plate 26 in the order of the plate opening W[1], the plate opening W[2], the plate opening W[3], and the plate opening W[4] from the -X direction to the +X direction.

[0027] FIG. 3 is an exploded perspective view of the head chip 3. FIG. 4 is a cross-sectional view taken along line III-III of the head chip 3 in FIG. 3. However, in FIG. 4, in addition to the head chip 3, the fixing plate 26 is shown.

[0028] As shown in FIGS. 3 and 4, the head chip 3 includes a flow path substrate 35, a pressure chamber forming substrate 34 provided on the upper surface of the flow path substrate 35, a diaphragm 33 provided on the upper surface of the pressure chamber forming substrate 34, a protection plate 32 provided on the upper surface of the diaphragm 33, a case 31 provided on the upper surfaces of the flow path substrate 35 and the protection plate 32, and a nozzle plate C and a compliance portion 36 provided on the lower surface of the flow path substrate 35. A plurality of nozzles N are formed in the nozzle plate C. Specifically, in the nozzle plate C, a nozzle row L1 composed of a plurality of nozzles N1 and a nozzle row L2 composed of a plurality of nozzles N2 are formed.

[0029] The pressure chamber forming substrate 34 is a flat member formed of, for example, a single crystal silicon substrate. A plurality of pressure chambers 341 corresponding to the plurality of nozzles N1 and a plurality of pressure chambers 342 corresponding to the plurality of nozzles N2 are formed in the pressure chamber forming substrate 34.

[0030] The flow path substrate 35 is a flat member constituting the ink flow path and is formed of, for example, a single crystal silicon substrate. The pressure chamber forming substrate 34 is provided on the upper surface of the flow path substrate 35.

[0031] In addition, in the flow path substrate 35, one opening 351, a plurality of communication flow paths 35L corresponding to the plurality of nozzles N1, and a plurality of discharge flow paths 357 corresponding to the plurality of nozzles N1 are formed. Here, the discharge flow path 357 is a flow path that communicates the pressure chamber 341 and the nozzle N1. The communication flow path 35L is a flow path that communicates the opening 351 and the pressure chamber 341 and includes the flow path 353 and the flow path 355. In the present embodiment, a case where a plurality of flow paths 353 are provided corresponding to the plurality of nozzles N1 in the flow path substrate 35 is illustrated, but in the flow path substrate 35, a single flow path 353 may be provided so as to be common to the plurality of nozzles N1.

[0032] In addition, in the flow path substrate 35, one opening 352, a plurality of communication flow paths 35R corresponding to the plurality of nozzles N2, and a plurality of discharge flow paths 358 corresponding to the plurality of nozzles N2 are formed. Here, the discharge flow path 358 is a flow path that communicates the pressure chamber 342 and the nozzle N2. The communication flow path 35R is a flow path that communicates the opening 352 and the pressure chamber 342 and includes the flow path 354 and the flow path 356. In the present embodiment, a case where a plurality of flow paths 354 are provided corresponding to the plurality of nozzles N2 in the flow path substrate 35 is illustrated, but in the flow path substrate 35, a single flow path 354 may be provided so as to be common to the plurality of nozzles N2.

[0033] The compliance unit 36 is a mechanism for suppressing pressure fluctuations in the flow path of the head chip 3, and is configured to include two sealing plates 361 and two supports 362. The sealing plate 361 is a flexible film-like resin member. Of the two sealing plates 361, one sealing plate 361 closes the opening 351 and the flow path 353 provided in the flow path substrate 35 from the +Z direction side. Of the two sealing plates 361, the other sealing plate 361 closes the opening 352 and the flow path 354 provided in the flow path substrate 35 from the +Z direction side. The support 362 is formed of a metal such as stainless steel. The support 362 fixes the sealing plate 361 to the flow path substrate 35. Note that the two sealing plates 361 may be a common single sealing plate 361, and the two supports 362 may be a common single support 362.

[0034] A diaphragm 33 is provided on the upper surface of the pressure chamber forming substrate 34. The diaphragm 33 is an elastically vibratable flat member, and is configured by a laminate of an elastic film formed of an elastic material such as silicon oxide and an insulating film formed of an insulating material such as zirconium oxide. Note that the pressure chambers 341 and 342 described above are spaces sandwiched between the upper surface of the flow path substrate 35 and the lower surface of the diaphragm 33.

[0035] As shown in FIGS. 3 and 4, a piezoelectric element 331 is provided on the upper surface of the diaphragm 33 so as to overlap a part or all of the pressure chamber 341 when viewed in the +Z direction. Also, a piezoelectric element 332 is provided on the upper surface of the diaphragm 33 so as to overlap a part or all of the pressure chamber 342 when viewed in the +Z direction. The piezoelectric element 331 is provided corresponding to the nozzle row L1 provided in the head chip 3. The piezoelectric element 332 is provided corresponding to the nozzle row L2 provided in the head chip 3. That is, the piezoelectric element 331 or 332 is provided corresponding to all the nozzles N provided in the head chip 3.

[0036] As shown in FIG. 4, a case 31 is fixed to the upper surfaces of the flow path substrate 35 and the protection plate 32. The case 31 is integrally formed by molding a resin material, for example. In Case 31, a space 313 that forms a storage chamber H1 together with the opening 351 of the flow path substrate 35, and a supply port 311 that communicates the storage chamber H1 and the supply flow path 251 are formed. Ink introduced from the supply port 311 is stored in the storage chamber H1. The ink stored in the storage chamber H1 is supplied to the pressure chamber 341 via the communication flow path 35L. The ink supplied to the pressure chamber 341 is discharged from the nozzle N1 in the +Z direction via the discharge flow path 357. Also, in Case 31, a space 314 that forms a storage chamber H2 together with the opening 352 of the flow path substrate 35, and a supply port 312 that communicates the storage chamber H2 and the supply flow path 251 are formed. Ink introduced from the supply port 312 is stored in the storage chamber H2. The ink stored in the storage chamber H2 is supplied to the pressure chamber 342 via the communication flow path 35R. The ink supplied to the pressure chamber 342 is discharged from the nozzle N2 in the +Z direction via the discharge flow path 358.

[0037] The wiring substrate 30 is inserted through an opening 310 that penetrates the case 31 in the Z-axis direction and an opening 320 that penetrates the protective plate 32 in the Z-axis direction, and the end of the wiring substrate 30 is joined to the diaphragm 33. The wiring substrate 30 is a wiring substrate on which wiring for transmitting the drive signal Com to the piezoelectric elements 331 and 332 is formed. As shown in FIGS. 3 and 4, a drive circuit 300 is provided on the wiring substrate 30. The drive signal Com and the print signal SI are supplied from the control unit 8 to the drive circuit 300. Based on the print signal SI, the drive circuit 300 switches whether to supply the drive signal Com to each of the plurality of piezoelectric elements 331 and each of the plurality of piezoelectric elements 332.

[0038] The fixing plate 26 is a flat plate-shaped member. The fixing plate 26 is formed of metal. A metal suitable for forming the fixing plate 26 is, for example, stainless steel. As shown in FIGS. 2 and 4, the fixing plate 26 is provided with a plurality of plate openings W corresponding to the plurality of head chips 3 of the head module 2. Each plate opening W has a shape corresponding to the nozzle plate C. Specifically, the plate opening W is a rectangular shape elongated in the Y-axis direction. In the present embodiment, when the head module 2 is viewed in the -Z direction, each head chip 3 is fixed to the lower surface of the fixing plate 26 with, for example, an adhesive in a state where the nozzle plate C is positioned inside the plate opening W. Thereby, the nozzles N of each nozzle row are respectively arranged in the plate opening W.

[0039] FIG. 23 is a block diagram showing a transmission path of a drive signal Com in the inkjet printer 1 according to the first embodiment. As illustrated in FIG. 23, the control unit 8 includes one drive signal generation circuit 85. The drive signal generation circuit 85 generates a drive signal Com, which is a signal for ejecting ink from the nozzles N by driving the piezoelectric elements 331 and 332. Further, the drive signal generation circuit 85 generates the drive signal Com every fixed time t. The generated drive signal Com is supplied to the piezoelectric elements 331 and 332 provided for all the nozzles N provided for all the head chips 3 included in the head module 2 of the inkjet printer 1 via the wiring 851, the wiring 852, the connector 249, the wiring pattern formed on the circuit board 24, the board terminal 243, the wiring board 30, and the drive circuit 300. In the first embodiment, the control unit 8 includes one wiring 851. The wiring 851 is a common wiring for supplying the drive signal Com generated in the drive signal generation circuit 85 to the plurality of piezoelectric elements 331 and 332. Therefore, the drive signal generation circuit 85 can supply a common drive signal Com to the piezoelectric elements 331 and the piezoelectric element 332. That is, the drive signal generation circuit 85 supplies a drive signal Com having the same waveform shape to all the piezoelectric elements 331 and the piezoelectric element 332 at the same timing every time t.

[0040] 1.3. Regarding the position of the nozzle and the formation of dots by ink ejection FIG. 5 is an explanatory diagram showing the positional relationship between the nozzle plate C of the head module 2 according to the first embodiment and the fixed plate 26. Note that FIG. 5 shows various positional relationships when the head module 2 is viewed in perspective from the -Z direction to the +Z direction.

[0041] As shown in FIG. 5, the head module 2 includes nozzle plates C[1], C[2], C[3], and C[4]. Each of the nozzle plates C[1], C[2], C[3], and C[4] constitutes a different head chip 3. Here, assuming that the four nozzle plates composed of the nozzle plates C[1], C[2], C[3], and C[4] all have a common structure, these four nozzle plates are collectively referred to as the nozzle plate C[m]. Here, the value m is an arbitrary natural number satisfying 1 ≦ m ≦ 4. In the following, when the head module 2 includes M nozzle plates C, the head module 2 may be expressed as including the nozzle plates C[1] to C[M]. In this case, the value M is a natural number of 2 or more, and the value m is an arbitrary natural number satisfying 1 ≦ m ≦ M. In the first embodiment, M = 4. Also, the m-th nozzle plate C[m] is arranged farther away from the reference nozzle plate C[1] in the +X direction as the value m becomes larger than 1. When the head module 2 includes four nozzle plates C, the value m can take any value satisfying 1 ≦ m ≦ 4, but unless otherwise specified, the value m is a specific value (for example, "m = 1") satisfying 1 ≦ m ≦ 4. Also, when the head module 2 includes M nozzle plates C, the value m can take any value satisfying 1 ≦ m ≦ M, but unless otherwise specified, the value m is a specific value (for example, "m = 1") satisfying 1 ≦ m ≦ M.

[0042] In the first embodiment, for a value m which is an arbitrary natural number satisfying 1 ≦ m ≦ M, the nozzle plate C[m] includes a nozzle row L1[m] and a nozzle row L2[m] each having J nozzles N for ejecting ink. That is, the nozzle plate C[1] includes a nozzle row L1[1] having J nozzles N for ejecting ink and a nozzle row L2[1] having J nozzles N for ejecting ink. Also, the nozzle plate C[2] includes a nozzle row L1[2] having J nozzles N for ejecting ink and a nozzle row L2[2] having J nozzles N for ejecting ink. Also, the nozzle plate C[3] includes a nozzle row L1[3] having J nozzles N for ejecting ink and a nozzle row L2[3] having J nozzles N for ejecting ink. Also, the nozzle plate C[4] includes a nozzle row L1[4] having J nozzles N for ejecting ink and a nozzle row L2[4] having J nozzles N for ejecting ink. Here, the nozzle row L1[m] and the nozzle row L2[m] are parallel to each other. Also, the nozzle plate C[m] is fixed such that the nozzle row L1[m] and the nozzle row L2[m] intersect the main scanning direction, which is the X-axis direction in this embodiment. Specifically, the nozzle plate C[m] is fixed such that both the nozzle row L1[m] and the nozzle row L2[m] are parallel to the Y-axis direction. Note that the value J is a natural number of 2 or more.

[0043] In the present embodiment, both the nozzle row L1[m] and the nozzle row L2[m] are provided at positions where the distances from the center of the nozzle plate C[m] in the X-axis direction are equal. That is, in the present embodiment, both the nozzle row L1[1] and the nozzle row L2[1] are provided at positions where the distances from the center of the nozzle plate C[1] in the X-axis direction are equal. Also, in the present embodiment, both the nozzle row L1[2] and the nozzle row L2[2] are provided at positions where the distances from the center of the nozzle plate C[2] in the X-axis direction are equal. Also, in the present embodiment, both the nozzle row L1[3] and the nozzle row L2[3] are provided at positions where the distances from the center of the nozzle plate C[3] in the X-axis direction are equal. Also, in the present embodiment, both the nozzle row L1[4] and the nozzle row L2[4] are provided at positions where the distances from the center of the nozzle plate C[4] in the X-axis direction are equal. In the present embodiment, the nozzle row L1[m] is provided at a position shifted -X direction from the center of the nozzle plate C[m], and the nozzle row L2[m] is provided at a position shifted +X direction from the center of the nozzle plate C[m]. That is, in the present embodiment, the nozzle row L1[1] is provided at a position shifted -X direction from the center of the nozzle plate C[1], and the nozzle row L2[1] is provided at a position shifted +X direction from the center of the nozzle plate C[1]. Also, in the present embodiment, the nozzle row L1[2] is provided at a position shifted -X direction from the center of the nozzle plate C[2], and the nozzle row L2[2] is provided at a position shifted +X direction from the center of the nozzle plate C[2]. Also, in the present embodiment, the nozzle row L1[3] is provided at a position shifted -X direction from the center of the nozzle plate C[3], and the nozzle row L2[3] is provided at a position shifted +X direction from the center of the nozzle plate C[3]. Also, in the present embodiment, the nozzle row L1[4] is provided at a position shifted -X direction from the center of the nozzle plate C[4], and the nozzle row L2[4] is provided at a position shifted +X direction from the center of the nozzle plate C[4]. Note that the center of the nozzle plate C[m] here refers to the geometric center of the nozzle plate C[m] observed when viewed in the Z-axis direction. In the present embodiment, the distance in the X-axis direction between nozzle row L1[m] and nozzle row L2[m] is represented as the nozzle row distance DL. That is, in the present embodiment, the distance in the X-axis direction between nozzle row L1[1] and nozzle row L2[1] is the nozzle row distance DL. Also, in the present embodiment, the distance in the X-axis direction between nozzle row L1[2] and nozzle row L2[2] is the nozzle row distance DL. Also, in the present embodiment, the distance in the X-axis direction between nozzle row L1[3] and nozzle row L2[3] is the nozzle row distance DL. Also, in the present embodiment, the distance in the X-axis direction between nozzle row L1[4] and nozzle row L2[4] is the nozzle row distance DL. In the present embodiment, it is assumed that in the X-axis direction, the center of head chip 3[m] coincides with the center of nozzle plate C[m] provided in head chip 3[m]. That is, in the present embodiment, it is assumed that in the X-axis direction, the center of head chip 3[1] coincides with the center of nozzle plate C[1] provided in head chip 3[1]. Also, in the present embodiment, it is assumed that in the X-axis direction, the center of head chip 3[2] coincides with the center of nozzle plate C[2] provided in head chip 3[2]. Also, in the present embodiment, it is assumed that in the X-axis direction, the center of head chip 3[3] coincides with the center of nozzle plate C[3] provided in head chip 3[3]. Also, in the present embodiment, it is assumed that in the X-axis direction, the center of head chip 3[4] coincides with the center of nozzle plate C[4] provided in head chip 3[4]. However, the present invention is not limited to such an aspect. In the X-axis direction, the center of each head chip 3 does not necessarily coincide with the center of nozzle plate C[m] provided in each head chip 3. Also, the distance between two nozzles N is obtained based on the geometric center of each of the two nozzles N as observed in the Z-axis direction. Also, the distance in the X-axis direction between two nozzle rows is obtained based on the geometric center of each of the total two nozzles N provided in each of the two nozzle rows as observed in the Z-axis direction.

[0044] In the first embodiment, for the nozzle N provided at the j1-th position in the +Y direction from the -Y direction side end on the nozzle row L1[m] provided in the nozzle plate C[m], it is represented as nozzle N1[m]{j1}. Here, the value j1 is a natural number satisfying 1 ≦ j1 ≦ J. Note that the nozzle N1[m]{1}, which is the nozzle N provided at the first position in the +Y direction from the -Y direction side end on the nozzle row L1[m] provided in the nozzle plate C[m], is the nozzle N located on the most -Y direction side on the nozzle row L1[m]. Similarly, for the nozzle N provided at the j2-th position in the +Y direction from the -Y direction side end on the nozzle row L2[m] provided in the nozzle plate C[m], it is represented as nozzle N2[m]{j2}. Here, the value j2 is a natural number satisfying 1 ≦ j2 ≦ J. Note that the nozzle N2[m]{1}, which is the nozzle N provided at the first position in the +Y direction from the -Y direction side end on the nozzle row L2[m] provided in the nozzle plate C[m], is the nozzle N located on the most -Y direction side on the nozzle row L2[m].

[0045] In this embodiment, the J nozzles N included in the nozzle row L1[m] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. Also, in this embodiment, the J nozzles N included in the nozzle row L2[m] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. Specifically, the J nozzles N included in the nozzle row L1[1] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. The J nozzles N included in the nozzle row L2[1] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. The J nozzles N included in the nozzle row L1[2] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. The J nozzles N included in the nozzle row L2[2] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. The J nozzles N included in the nozzle row L1[3] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. The J nozzles N included in the nozzle row L2[3] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. The J nozzles N included in the nozzle row L1[4] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant. The J nozzles N included in the nozzle row L2[4] are evenly arranged such that the intervals between two adjacent nozzles N in the Y-axis direction are constant.

[0046] The nozzle N1[m]{j} in the nozzle plate C[m] is provided at a position shifted in the -Y direction with respect to the nozzle N2[m]{j}. In the Y-axis direction, the nozzle interval between the nozzle N1[m]{j} and the nozzle N2[m]{j} is equal to the nozzle interval between the nozzle N2[m]{j} and the nozzle N1[m]{j+1}, and this interval is referred to as the interval R. In other words, in the Y-axis direction, among the J nozzles N included in the nozzle row L1[m], between the adjacent nozzles N1[m]{j} and N1[m]{j+1}, the nozzle N2[m]{j} among the J nozzles N included in the nozzle row L2[m] is provided. Here, the value j is a natural number satisfying 1 ≦ j ≦ J-1. Specifically, in the Y-axis direction, among the J nozzles N included in the nozzle row L1[1], between two adjacent nozzles N1[1]{j} and N1[1]{j + 1}, a nozzle N2[1]{j} among the J nozzles N included in the nozzle row L2[1] is provided. Also, in the Y-axis direction, among the J nozzles N included in the nozzle row L1[2], between two adjacent nozzles N1[2]{j} and N1[2]{j + 1}, a nozzle N2[2]{j} among the J nozzles N included in the nozzle row L2[2] is provided. Also, in the Y-axis direction, among the J nozzles N included in the nozzle row L1[3], between two adjacent nozzles N1[3]{j} and N1[3]{j + 1}, a nozzle N2[3]{j} among the J nozzles N included in the nozzle row L2[3] is provided. Also, in the Y-axis direction, among the J nozzles N included in the nozzle row L1[4], between two adjacent nozzles N1[4]{j} and N1[4]{j + 1}, a nozzle N2[4]{j} among the J nozzles N included in the nozzle row L2[4] is provided. Also, in the Y-axis direction, the distance between the nozzle N1[1]{j} and the nozzle N2[1]{j} is the distance R, and the distance between the nozzle N2[1]{j} and the nozzle N1[1]{j + 1} is the distance R. Also, in the Y-axis direction, the distance between the nozzle N1[2]{j} and the nozzle N2[2]{j} is the distance R, and the distance between the nozzle N2[2]{j} and the nozzle N1[2]{j + 1} is the distance R. Also, in the Y-axis direction, the distance between the nozzle N1[3]{j} and the nozzle N2[3]{j} is the distance R, and the distance between the nozzle N2[3]{j} and the nozzle N1[3]{j + 1} is the distance R. Also, in the Y-axis direction, the distance between the nozzle N1[4]{j} and the nozzle N2[4]{j} is the distance R, and the distance between the nozzle N2[4]{j} and the nozzle N1[4]{j + 1} is the distance R.

[0047] In the first embodiment, the distance between two corresponding nozzle rows provided on the two nozzle plates C[m1] and C[m2] is expressed as follows. In the X-axis direction, the distance between the nozzle row L1[m1] provided in the nozzle plate C[m1] and the nozzle row L1[m2] provided in the nozzle plate C[m2] is represented as the nozzle row distance D1[m1][m2]. Similarly, the distance between the nozzle row L2[m1] provided in the nozzle plate C[m1] and the nozzle row L2[m2] provided in the nozzle plate C[m2] is represented as the nozzle row distance D2[m1][m2]. Here, the values m1 and m2 are any natural numbers satisfying 1 ≦ m1 < m2 ≦ M. When the values m1 and m2 satisfy "m2 = 1 + m1", the nozzle plate C[m2] is adjacent to the nozzle plate C[m1] in the +X direction of the nozzle plate C[m1].

[0048] The fixed plate 26 is provided with M plate openings W[1] to W[M] that correspond one-to-one with the M nozzle plates C[1] to C[M]. The head chip 3[m] is fixed to the fixed plate 26 such that the nozzle rows L1[m] and L2[m] provided in the nozzle plate C[m] included in the head chip 3[m] are exposed from the plate opening W[m] provided in the fixed plate 26. Here, it is assumed that the M plate openings W[1] to W[M] provided in the fixed plate 26 all have the same shape. The plate opening W[m2] is provided in the +X direction of the plate opening W[m1].

[0049] In the first embodiment, it is assumed that the nozzle plates C[1] to C[M] are all fixed at the same position in the Y-axis direction. In this case, for the values m1 and m2, which are any natural numbers satisfying 1 ≦ m1 < m2 ≦ M, the nozzle N1[m1]{j1} on the nozzle row L1[m1] and the nozzle N1[m2]{j1} on the nozzle row L1[m2] are arranged at the same position in the Y-axis direction. That is, the nozzle N1[1]{j1} on the nozzle row L1[1], the nozzle N1[2]{j1} on the nozzle row L1[2], the nozzle N1[3]{j1} on the nozzle row L1[3], and the nozzle N1[4]{j1} on the nozzle row L1[4] are arranged at the same position in the Y-axis direction.

[0050] In the X-axis direction, the distance between the center of the plate opening W[m1] and the center of the plate opening W[m2] is represented as the plate opening interval U[m1][m2]. Here, the center of the plate opening W[m] refers to the geometric center of the plate opening W[m] observed when viewed in the Z-axis direction.

[0051] In the first embodiment, when the values m1 and m2 satisfy "m2 = 1 + m1" and M ≥ 3, it is assumed that the plate opening interval U[m1][m2] becomes a constant interval. That is, in this embodiment, it is assumed that the plate opening intervals U[1][2] to U[M - 1][M] are all equal. Also, in this embodiment, it is assumed that the nozzle plate C[m] is fixed so that the relative positional relationship in the X-axis direction between the nozzle plate C[m] and the plate opening W[m] is constant. Specifically, in this embodiment, it is assumed that the distance between the center of the nozzle plate C[m] and the center of the plate opening W[m] in the X-axis direction is constant. More specifically, in the X-axis direction, it is assumed that the distances between the centers of the nozzle plate C[1] and the plate opening W[1], between the centers of the nozzle plate C[2] and the plate opening W[2], between the centers of the nozzle plate C[3] and the plate opening W[3], and between the centers of the nozzle plate C[4] and the plate opening W[4] are constant. In this case, the nozzle row intervals D1[1][2] to D1[M - 1][M] and the nozzle row intervals D2[1][2] to D2[M - 1][M] are all equal.

[0052] FIG. 6 to FIG. 8 are explanatory diagrams illustrating the positional relationship between the operation of the head module 2 and the positions of the dots Dt formed when performing a printing operation using the head module 2 shown in FIG. 5. In FIGS. 6 to 8, the positions of the nozzles N at each time are shown by solid-line rectangles. Also, the positions of the M nozzle plates C[1] to C[M] each having a plurality of nozzles N are shown by dashed-line rectangles. Further, the positions of the dots Dt formed by the ink ejected from the nozzles N are shown by hatched regions in the rectangles. In FIGS. 6 to 8, out of the total 2×M×J nozzles N provided on the M nozzle plates C[1] to C[M] of the head module 2 shown in FIG. 5, M nozzles N1[1]{j} to N1[M]{j}, M nozzles N2[1]{j} to N2[M]{j}, M nozzles N1[1]{j + 1} to N1[M]{j + 1}, and M nozzles N2[1]{j + 1} to N2[M]{j + 1} are focused on to explain the printing operation. As described above, in the present embodiment, the case where M = 4 is assumed. Therefore, in FIGS. 6 to 8, out of the total 8×J nozzles N provided on the M nozzle plates C[1] to C[4] of the head module 2, 4 nozzles N1[1]{j} to N1[4]{j}, 4 nozzles N2[1]{j} to N2[4]{j}, 4 nozzles N1[1]{j + 1} to N1[4]{j + 1}, and 4 nozzles N2[1]{j + 1} to N2[4]{j + 1} are shown.

[0053] Figs. 6 to 8 illustrate the process of forming dot Dt when the head module 2 discharges ink while moving in the +X direction of the X-axis direction, which is the main scanning direction, over time. Among these, Fig. 6 illustrates the positional relationship between the head module 2 and dot Dt when the time T is from Tc + 0t to Tc + 3t. Fig. 7 illustrates the positional relationship between the head module 2 and dot Dt when the time T is from Tc + 4t to Tc + 7t. Fig. 8 illustrates the positional relationship between the head module 2 and dot Dt when the time T is from Tc + 8t to Tc + 11t. Here, the time Tc represents the time when the supply of the print signal SI to the head module 2 is started for the printing operation. The time t is the time from when the head module 2 forms dot Dt until it forms the next dot Dt. For clarity, the position of the nozzle plate C[m] in the X-axis direction at each time is illustrated below the rectangular dashed line indicating the head module 2 using a rectangular dashed line having the same height as the interval R. Also, for the sake of illustration, in Figs. 6 to 8, dot Dt is a square having a width equal to the interval R in both the X-axis direction and the Y-axis direction, and all dots Dt are regarded as having the same shape.

[0054] As described above, in the first embodiment, the time t is the time from when the head module 2 forms dot Dt until it forms the next dot Dt. In other words, the time t is the period during which the drive signal Com is generated and supplied to the piezoelectric elements 331 and 332 provided corresponding to the nozzle N that discharges the ink for forming dot Dt. Also, the time t is a value subject to constraints due to conditions such as the responsiveness and stability of the fluid motion of the ink. For example, when the scanning speed of the head module 2 is doubled to a predetermined reference speed, the minimum interval of the dots Dt formed using a certain specific nozzle N becomes twice that when the head module 2 is scanned at the predetermined reference speed. Therefore, when the scanning speed of the head module 2 is doubled to a predetermined reference speed, the resolution in the X-axis direction becomes half that when the head module 2 is scanned at the predetermined reference speed. Here, even when the scanning speed of the head module 2 is doubled to a predetermined reference speed, if the time t, which is the period during which the dot Dt is formed, can be halved, the minimum interval of the dots Dt formed using a certain specific nozzle N can be made equal to that when the scanning speed of the head module 2 is the predetermined reference speed. However, the time t determined subject to the above-mentioned constraints cannot be set to an arbitrary value. That is, there may be cases where the time t, which is the period during which the dot Dt is formed, cannot be halved. For this reason, the scanning speed becomes the rate-determining condition when determining the resolution. That is, when the scanning speed of the head module 2 is doubled to a predetermined reference speed, the minimum interval of the dots Dt formed using a certain specific nozzle N cannot be made equal to that when the scanning speed of the head module 2 is the predetermined reference speed.

[0055] In the first embodiment, the head module 2 ejects the first ink at time T = Tc + 1t to form a dot Dt on the recording paper PE, and thereafter, forms a new dot Dt every time t elapses. For convenience of illustration, in each of the times shown in FIGS. 6 to 8, a so-called solid printing process is illustrated in which ink is ejected from all the nozzles N provided in the head module 2 at the same timing to form the dot Dt without gaps, but the present invention is not limited to this. The head module 2 may form the dot Dt by ejecting ink from some of the nozzles N. Specifically, by supplying a print signal SI to the head module 2 and specifying whether to supply a drive signal Com to the piezoelectric element corresponding to each of the nozzles N, the dot Dt can be formed at a predetermined position every time t. Further, since all the nozzles N provided in the head module 2 are supplied with the ink introduced from the common pinhole 211 as described above, they all eject the same type of ink to form the dot Dt.

[0056] Note that various dimensions and arrangements in the X-axis direction of the head module 2, the head chip 3, the nozzle plate C, the nozzle N, etc. are set based on the basic resolution unit ΔX in the X-axis direction. Here, the resolution in the X-axis direction of an image formed by a general inkjet printer is defined as the basic resolution. The basic resolution (dpi) is a value obtained by multiplying 100 by a natural number, or a value obtained by multiplying 90 by a natural number. For example, it can be 100 dpi, 200 dpi, 300 dpi, 400 dpi, 600 dpi, 900 dpi, 1200 dpi, 2400 dpi, 90 dpi, 180 dpi, 360 dpi, 540 dpi, 720 dpi, 1080 dpi. And the basic resolution unit ΔX is a length corresponding to the basic resolution, and it corresponds to the interval in the X-axis direction between adjacent dots Dt in an image printed by solid printing. Note that the interval in the X-axis direction between adjacent dots Dt refers to the interval between the centers of adjacent dots Dt. Also, the basic resolution unit ΔX can also be described as the length obtained by dividing 1 inch by the maximum number of dots Dt that can be formed in 1 inch in the X-axis direction. As described above, since the basic resolution unit ΔX corresponds to the basic resolution, the basic resolution unit ΔX is a value obtained by dividing 1 by a value obtained by multiplying 100 by a natural number, or a value obtained by dividing 1 by a value obtained by multiplying 90 by a natural number. For example, it can be 1 / 100 inch, 1 / 200 inch, 1 / 300 inch, 1 / 400 inch, 1 / 600 inch, 1 / 900 inch, 1 / 1200 inch, 1 / 2400 inch, 1 / 90 inch, 1 / 180 inch, 1 / 360 inch, 1 / 540 inch, 1 / 720 inch, 1 / 1080 inch. That is, for example, when the basic resolution in the X-axis direction is 600 dpi, the basic resolution unit ΔX is 1 / 600 inch, and when the basic resolution in the X-axis direction is 360 dpi, the basic resolution unit ΔX is 1 / 360 inch. Also, the scanning speed of the head module 2 in the X-axis direction is set based on the basic resolution unit ΔX. For example, after the time T = Tc + 1t, the head module 2 is scanned at a speed such that it advances by an interval G set based on the basic resolution unit ΔX every time a time t elapses. Specifically, the interval G is set to a natural multiple of the basic resolution unit ΔX.

[0057] In addition, various dimensions and arrangements in the Y-axis direction of the head module 2, the head chip 3, the nozzle plate C, the nozzle N, etc. are set based on the basic resolution unit ΔY in the Y-axis direction. The basic resolution unit ΔY is, similar to the basic resolution unit ΔX described above, a value obtained by dividing 1 by a value obtained by multiplying 100 by a natural number, or a value obtained by dividing 1 by a value obtained by multiplying 90 by a natural number. For example, the interval R is set based on the basic resolution unit ΔY. Specifically, the interval R is set to a natural number multiple of the basic resolution unit ΔY. In the first embodiment, as an example, it is assumed that the basic resolution unit ΔX is equal to the basic resolution unit ΔY. Also, in the first embodiment, as an example, it is assumed that the interval R is set to be equal to the basic resolution unit ΔX and the basic resolution unit ΔY.

[0058] In this embodiment, the interval G is set to M times the basic resolution unit ΔX. As described above, in this embodiment, the interval R is set to be equal to the basic resolution unit ΔX. Therefore, in this embodiment, the interval G is equal to M times the basic resolution unit ΔX, in other words, M times the interval R. That is, in this embodiment, the interval G is G = M×ΔX. More specifically, in this embodiment, as described above, M = 4. Thus, in this embodiment, the scanning speed of the head module 2 is set so that the interval G is G = 4ΔX. Furthermore, in this embodiment, since the interval R is set to be equal to the basic resolution unit ΔX, the scanning speed of the head module 2 is set so that the interval G is G = 4R. In FIGS. 6 to 8, for convenience of explanation, as the X-axis coordinate AX, the position of the nozzle N1[1]{j} at the time T = Tc + 1t is set to "0", and a value that increases by "1" every time it moves in the +X direction by the basic resolution unit ΔX is assigned. For example, in FIGS. 6 to 8, while the time T elapses from Tc + 1t to Tc + 2t, the position of the nozzle N2[4]{j} provided in the head module 2 moves from AX = 31 to AX = 35.

[0059] Further, the nozzle row interval DL is set based on the basic resolution unit ΔX in the X-axis direction. Specifically, the nozzle row interval DL is set to a natural number multiple of the basic resolution unit ΔX. Also, in the first embodiment, the aforementioned interval G is set to a value obtained by dividing the nozzle row interval DL by a natural number. In other words, in this embodiment, the nozzle row interval DL is set to α times the interval G. That is, in this embodiment, the nozzle row interval DL is set to (M × α) times the basic resolution unit ΔX. That is, DL = (M × α)ΔX. In this embodiment, since the interval R is set to be equal to the basic resolution unit ΔX, the nozzle row interval DL is set to (M × α) times the interval R. That is, in this embodiment, DL = (M × α)R. Here, the value α is a natural number of 1 or more. That is, in the head module 2 that moves by (M × 1)ΔX every time the time t elapses, the nozzle row L1[1] forms a dot Dt with respect to the nozzle row L2[1] provided at a position (M × α)ΔX away from the nozzle row L1[1] at the time T, and after α times the time t has elapsed from the time T, the dot Dt can be formed at the same position in the X-axis direction.

[0060] Also, as described above, the nozzle row interval D1[1][ma] is determined based on the basic resolution unit ΔX in the X-axis direction. Here, the value ma is an arbitrary natural number satisfying 2 ≤ ma ≤ M. Note that the value ma can take any value satisfying 2 ≤ ma ≤ M, but unless otherwise specified, the value ma is a specific value (for example, "ma = 2") satisfying 2 ≤ ma ≤ M. In this case, for the value ma which is an arbitrary natural number satisfying 2 ≤ ma ≤ M, the nozzle row interval D1[1][ma] is set to a natural number multiple of the basic resolution unit ΔX. That is, the nozzle row interval D1[1][2], the nozzle row interval D1[1][3], and the nozzle row interval D1[1][4] are set to natural number multiples of the basic resolution unit ΔX. As described above, the head module 2 moves by an interval G every time the time t elapses, in other words, by M times the basic resolution unit ΔX. And in order to make the minimum interval of the dots Dt formed by the head module 2 be the basic resolution unit ΔX, it is preferable that the nozzle row L1[ma] is provided at a position different from the dots Dt formed by the nozzle row L1[1] and the nozzle row L2[1] in the X-axis direction so as to be able to form the dots Dt. In other words, it is preferable that the nozzle row L1[ma] is provided at a position that complements the position of the dots Dt formed by the nozzle row L1[1] in the X-axis direction so as to be able to form the dots Dt. Here, an explanation will be given about "complement". As described above, in the present embodiment, since the nozzle N1[1]{j1} of the nozzle row L1[1] and the nozzle N1[ma]{j1} of the nozzle row L1[ma] are arranged at the same position in the Y-axis direction, the nozzle row L1[1] and the nozzle row L1[ma] are nozzle rows forming the same raster line. And "complement" means discharging the dot Dt formed by the nozzle N1[ma]{j1} of the nozzle row L1[ma] between the adjacent dots Dt along the X-axis direction formed by the nozzle N1[1]{j1} of the nozzle row L1[1] to fill the gap. Specifically, it is preferable that the (M - 1) nozzle rows L1[2] to L1[M] are provided so as to be able to form (M - 1) dots between the two closest dots Dt formed by the nozzle row L1[1] in the X-axis direction.Therefore, in the first embodiment, the distance D1[1][ma] between the nozzle row L1[1] and the nozzle row L1[ma] is set to a distance different from a natural number multiple of the distance G. Specifically, the nozzle row distance D1[1][ma] is set to a distance obtained by adding β[ma] times the distance G and γ[ma] times the distance R. That is, the nozzle row distance D1[1][ma] is set to (M×β[ma]+γ[ma]) times the basic resolution unit ΔX, in other words, (M×β[ma]+γ[ma]) times the distance R. That is, D1[1][ma] = (M×β[ma]+γ[ma])ΔX. More specifically, in this embodiment, D1[1][2] = (M×β[2]+γ[2])ΔX, D1[1][3] = (M×β[3]+γ[3])ΔX, and D1[1][4] = (M×β[4]+γ[4])ΔX. Here, the value β[ma] is a natural number satisfying α < β[ma]. Also, the value γ[ma] is a natural number satisfying 1 ≤ γ[ma] ≤ M - 1. That is, when M = 2 is satisfied, γ[ma] = γ[2] is 1. Also, when M ≥ 3 is satisfied, the value γ[ma] satisfies γ[ma1] ≠ γ[ma2] when natural numbers ma1 and ma2 satisfy 2 ≤ ma1 < ma2 ≤ M. Here, for example, when M = 3 is satisfied, 1 ≤ γ[ma] ≤ 2, and when γ[ma1] is 1, γ[ma2] is 2, and when γ[ma1] is 2, γ[ma2] is 1. Also, when M = 4 is satisfied, 1 ≤ γ[ma] ≤ 3, and when γ[ma1] is 1, γ[ma2] is either 2 or 3, when γ[ma1] is 2, γ[ma2] is either 1 or 3, and when γ[ma1] is 3, γ[ma2] is either 1 or 2.

[0061] As described above, in the present embodiment, in the X-axis direction, the nozzle row interval DL and the nozzle row interval D1[1][ma] are set so as to satisfy DL:D1[1][ma]=M×α×ΔX:(M×β[ma]+γ[ma])×ΔX = M×α:M×β[ma]+γ[ma]. More specifically, in the present embodiment, in the X-axis direction, the nozzle row interval DL and the nozzle row interval D1[1][2] are set so as to satisfy DL:D1[1][2]=M×α:M×β[2]+γ[2]. Also, in the present embodiment, in the X-axis direction, the nozzle row interval DL and the nozzle row interval D1[1][3] are set so as to satisfy DL:D1[1][3]=M×α:M×β[3]+γ[3]. Further, in the present embodiment, in the X-axis direction, the nozzle row interval DL and the nozzle row interval D1[1][4] are set so as to satisfy DL:D1[1][4]=M×α:M×β[4]+γ[4].

[0062] As described above, in the first embodiment, it is assumed that M = 4. Also, as described above, in FIGS. 6 to 8, the position of the nozzle N1[1]{j} in the X-axis direction at time T = Tc + 1t is AX = 0. Also, the position of the nozzle N1[1]{j} in the X-axis direction at time T = Tc + 2t is AX = 4, and the position of the nozzle N1[1]{j} in the X-axis direction at time T = Tc + 3t is AX = 8. Therefore, the nozzle N1[1]{j} can form a dot Dt at AX = 4k - 4 at time T = Tc + kt. In other words, the nozzle N1[1]{j} can form a dot Dt at AX = 4×k1. Here, the variable k is a natural number of 1 or more. Also, the variable k1 is an integer that satisfies k1 = k - 1. Also, in FIGS. 6 to 8, the case where α = 1 is assumed. The nozzle N2[1]{j} is provided at a position shifted by an interval equal to the nozzle row interval DL in the +X direction from the nozzle N1[1]{j}. Further, in the present embodiment, since M = 4, the nozzle row interval DL is set to (M×α) times the basic resolution unit ΔX, in other words, (M×α) times the interval R, that is, 4 times the interval R. Therefore, since the nozzle N2[1]{j} is provided at a position shifted by 4ΔX in the +X direction from the nozzle N1[1]{j}, at time T = Tc + kt, dots Dt can be formed for AX = 4k. In other words, the nozzle N2[1]{j} can form dots Dt for AX = 4×(k1 + 1).

[0063] Also, in FIGS. 6 to 8, the position of the nozzle N1[2]{j} in the X-axis direction at time T = Tc + 1t is AX = 9. Since the position of the nozzle N1[1]{j} in the X-axis direction at time T = Tc + 1t is AX = 0, in FIGS. 6 to 8, substituting M = 4 and ma = 2 into the above formula, D1[1][2] = (4×β[2] + γ[2])ΔX = 9ΔX can be expressed. As described above, since α = 1 < β[ma] and 1 ≦ γ[ma] ≦ M - 1 = 3, in FIGS. 6 to 8, when ma = 2, β[2] = 2 and γ[2] = 1. And since the nozzle N1[2]{j} is provided at a position shifted by AX = +9 from the nozzle N1[1]{j}, at time T = Tc + kt, dots Dt can be formed for AX = 4k + 5. In other words, the nozzle N1[2]{j} can form dots Dt for AX = 4×k2 + 1. Here, the variable k2 is an integer that satisfies k2 = k + 1. That is, the variable k2 can be expressed as k2 = k + β[2] - 1. Also, from γ[2] = 1, the nozzle N1[2]{j} can form dots Dt for AX = 4×k2 + γ[2]. Also, in FIGS. 6 to 8, since the nozzle N2[2]{j} is provided at a position shifted by an interval equal to the nozzle row interval DL, i.e., 4ΔX, in the +X direction from the nozzle N1[2]{j}, at time T = Tc + kt, dots Dt can be formed for AX = 4k + 9. In other words, the nozzle N2[2]{j} can form dots Dt for AX = 4×(k2 + 1) + 1.

[0064] Also, in FIGS. 6 to 8, the position of the nozzle N1[3]{j} in the X-axis direction at time T = Tc + 1t is AX = 18. Since the position of the nozzle N1[1]{j} in the X-axis direction at time T = Tc + 1t is AX = 0, in FIGS. 6 to 8, substituting M = 4 and ma = 3 into the above formula, D1[1][3] = (4×β[3] + γ[3])ΔX = 18ΔX can be expressed. As described above, α = 1 < β[ma] and 1 ≤ γ[ma] ≤ M - 1 = 3, that is, in FIGS. 6 to 8, when ma = 3, β[3] = 4 and γ[3] = 2. And since the nozzle N1[3]{j} is provided at a position shifted by AX = +18 from the nozzle N1[1]{j}, at time T = Tc + kt, dots Dt can be formed for AX = 4k + 14. In other words, the nozzle N1[3]{j} can form dots Dt for AX = 4×k3 + 2. Here, the variable k3 is an integer that satisfies k3 = k + 3. That is, the variable k3 can be expressed as k3 = k + β[3] - 1. Also, from γ[3] = 2, the nozzle N1[3]{j} can form dots Dt for AX = 4×k3 + γ[3]. Also, in FIGS. 6 to 8, since the nozzle N2[3]{j} is provided at a position shifted by an interval equal to the nozzle row interval DL, i.e., 4ΔX, in the +X direction from the nozzle N1[3]{j}, at time T = Tc + kt, dots Dt can be formed for AX = 4k + 18. In other words, the nozzle N2[3]{j} can form dots Dt for AX = 4×(k3 + 1) + 2.

[0065] Also, in FIGS. 6 to 8, the position of the nozzle N1[4]{j} in the X-axis direction at time T = Tc + 1t is AX = 27. Since the position of the nozzle N1[1]{j} in the X-axis direction at time T = Tc + 1t is AX = 0, in FIGS. 6 to 8, substituting M = 4 and ma = 4 into the above formula, D1[1][4] = (4×β[4] + γ[4])ΔX = 27ΔX can be expressed. As described above, since α = 1 < β[ma] and 1 ≦ γ[ma] ≦ M - 1 = 3, that is, in FIGS. 6 to 8, when ma = 4, β[4] = 6 and γ[4] = 3. And since the nozzle N1[4]{j} is provided at a position shifted by AX = +27 from the nozzle N1[1]{j}, at time T = Tc + kt, dots Dt can be formed for AX = 4k + 23. In other words, the nozzle N1[4]{j} can form dots Dt for AX = 4×k4 + 3. Here, the variable k4 is an integer satisfying k4 = k + 5. That is, the variable k4 can be expressed as k4 = k + β[4] - 1. Also, from γ[4] = 3, the nozzle N1[4]{j} can form dots Dt for AX = 4×k4 + γ[4]. Also, in FIGS. 6 to 8, since the nozzle N2[4]{j} is provided at a position shifted by an interval equal to the nozzle row interval DL, that is, 4ΔX, in the +X direction from the nozzle N1[4]{j}, at time T = Tc + kt, dots Dt can be formed for AX = 4k + 27. In other words, the nozzle N2[4]{j} can form dots Dt for AX = 4×(k4 + 1) + 3.

[0066] As described above, the nozzle N1[1]{j} can form a dot Dt for AX = M × k1. Also, the nozzle N1[ma]{j} can form a dot Dt for AX = M × ka + γ[ma]. Here, the variable ka is an integer that satisfies ka = k + β[ma] - 1. And as described above, the value γ[ma] is a natural number that satisfies 1 ≤ γ[ma] ≤ M - 1, and when M ≥ 3, to satisfy γ[ma1] ≠ γ[ma2], the set of M - 1 values {γ[2], γ[3], …, γ[M]} is the same as the set of M - 1 values {1, 2, …, M - 1} or is the set of M - 1 values {1, 2, …, M - 1} with the order changed. Also, when M = 2, γ[ma] = γ[2] is 1. Therefore, according to the present embodiment, it is possible to form a plurality of dots Dt in the X-axis direction at intervals of R without overlap by the M nozzles N1[1]{j} to N1[M]{j}. That is, according to the present embodiment, it is possible to form a plurality of dots Dt in the X-axis direction at intervals of the basic resolution unit ΔX without overlap by the M nozzles N1[1]{j} to N1[M]{j}.

[0067] Specifically, in FIGS. 6 to 8, the nozzle N1[1]{j} can form a dot Dt for AX = 4 × k1. Also, in FIGS. 6 to 8, the nozzle N1[ma]{j} can form a dot Dt for AX = 4 × ka + γ[ma]. And in FIGS. 6 to 8, the set of three values {γ[2], γ[3], γ[4]} is the same as the set of three values {1, 2, 3} or is the set of three values {1, 2, 3} with the order changed. Therefore, in FIGS. 6 to 8, it is possible to form a plurality of dots Dt in the X-axis direction at intervals of R without overlap by the four nozzles N1[1]{j} to N1[4]{j}. That is, in FIGS. 6 to 8, it is possible to form a plurality of dots Dt in the X-axis direction at intervals of the basic resolution unit ΔX without overlap by the four nozzles N1[1]{j} to N1[4]{j}.

[0068] In this way, by performing the printing operation using the head module 2 in the first embodiment, printing can be performed without generating overlapping dots Dt or gaps in the X-axis direction. Specifically, in FIG. 8, it can be confirmed that the dots Dt are formed continuously in the +X direction from the X-axis coordinate AX of 28. That is, since there are gaps in the -X direction from the X-axis coordinate AX of 28, for example, an image formed by solid printing includes portions where the dots Dt are not formed. Therefore, in the actual printing operation, the dots Dt may be formed in the region after the X-axis coordinate AX of 28.

[0069] As described above, according to the present embodiment, the head module 2 can form the dots Dt at intervals of the basic resolution unit ΔX in the X-axis direction. In this embodiment, the basic resolution unit ΔX and the basic resolution unit ΔY are equal to the interval R. That is, according to the present embodiment, the head module 2 can form a plurality of dots Dt on the recording paper PE such that the interval between the dots Dt in the X-axis direction and the interval between the dots Dt in the Y-axis direction are both equal to the basic resolution unit.

[0070] Further, in this embodiment, as described above, the relationship that the nozzle row interval DL is α times the interval G is satisfied. Therefore, according to the present embodiment, the nozzle N1[m]{j} provided in the nozzle row L1[m] and the nozzle N2[m]{j} provided in the nozzle row L2[m] can form the dots Dt at the same position in the X-axis direction and at different positions in the Y-axis direction. That is, in the present embodiment, the nozzle N1[m]{j} and the nozzle N2[m]{j} which are provided at different positions in the Y-axis direction contribute to the improvement of the resolution in the Y-axis direction.

[0071] Also, in the present embodiment, as described above, the nozzle row interval D1[1][ma] satisfies the relationship of being different from a natural multiple of the interval G. Therefore, according to the present embodiment, the nozzles N1[ma]{j} provided in the nozzle row L1[ma] can form dots Dt at positions different from those of the dots Dt formed by the nozzles N1[1]{j} provided in the nozzle row L1[1] arranged with a nozzle row interval D1[1][ma] with respect to the nozzle row L1[ma] in the X-axis direction. That is, in the present embodiment, the inkjet printer 1 can perform printing that satisfies the desired basic resolution unit ΔX after setting the scanning speed in the X-axis direction of the head module 2 to a scanning speed that moves M times the basic resolution unit ΔX per unit time t.

[0072] Also, in the present embodiment, the intervals between the nozzle rows L1[1] and L2[1] and the nozzle row L1[ma] are set according to the assumed scanning speed. That is, the interval between the head chip 3[1] including the nozzle rows L1[1] and L2[1] and the head chip 3[ma] including the nozzle row L1[ma] is set according to the assumed scanning speed, specifically, the value M. That is, even when the minimum interval in the X-axis direction of the dots Dt formed by the nozzle rows L1[1] and L2[1] expands by increasing the scanning speed of the head module 2, it is possible to set the positions of the (M - 1) nozzle rows L1[2] to L1[M] corresponding to the nozzle rows L1[2] to L1[M] without changing the structure of the head chip 3, and printing can be performed without reducing the resolution by forming dots Dt at positions different from those of the dots Dt formed by the nozzle rows L1[1] and L2[1] from the nozzle rows L1[2] to L1[M].

[0073] In the above description, the value M was treated as the number of nozzle plates C that have a common structure, are fixed at the same position in the Y-axis direction, and are arranged at a predetermined interval in the X-axis direction. However, this is not the only case. The value M may also be treated as the number of nozzle rows that can eject the same type of ink in different raster columns in the same raster row. Specifically, in the head module 2QS according to the second embodiment and the head module 2B according to the fourth embodiment, which will be described later, when a nozzle plate C having a common structure is used to eject different types of ink or is fixed at different positions in the Y-axis direction, the value M is different from the number of nozzle plates C having a common structure.

[0074] In the above description, the nozzle row L1[ma] was treated as a nozzle row L1 provided on a nozzle plate [ma] different from the nozzle plate [1]. However, this is not the only case. The nozzle row L1[ma] may be any nozzle row that can eject the same type of ink in different raster columns in the same raster row with respect to the nozzle row L1[1]. The same applies to the nozzle row L2[ma].

[0075] Hereinafter, in order to clarify the effects of the present embodiment, the head module 2V according to the reference example will be described with reference to FIG. 22. The head module 2V is a head module mounted on an inkjet printer different from the inkjet printer 1 according to the first embodiment.

[0076] FIG. 22 is an explanatory diagram showing the positional relationship between the M nozzle plates C included in the head module 2V according to the reference example and the fixing plate 26C. Note that FIG. 22 shows various positional relationships when the head module 2V is viewed in perspective from the -Z direction to the +Z direction. Also, in FIG. 22, the case where M = 4 is illustrated for explanation. The head module 2V is configured in the same manner as the head module 2 according to the first embodiment, except that the fixed plate 26C has plate openings W[1] to W[M] through which each of the nozzle plates C[1] to C[M] is exposed, and the values of the nozzle row intervals D1[m1][m2] and D2[m1][m2] and the plate opening interval U[m1][m2] are different from those in the head module 2 according to the first embodiment. That is, the head chip 3 that constitutes the head module 2 of the first embodiment is the same as the head chip 3 that constitutes the head module 2V of the reference example. Also, the nozzle row interval DL in the first embodiment is the same as the nozzle row interval DL in the reference example.

[0077] In the reference example, similar to the first embodiment, it is assumed that the nozzle plates C[1] to C[M] provided in each of the M head chips 3 are all fixed at the same position in the Y-axis direction. Also, in the X-axis direction, it is assumed that the center of each of the M head chips 3 coincides with the center of the nozzle plate C[m] provided in each of the head chips 3. Also, the M head chips 3 are fixed to the fixed plate 26C such that the nozzle rows L1[m] and L2[m] provided in the nozzle plate C[m] provided in the head chip 3 are exposed from the plate opening W[m] provided in the fixed plate 26. Note that, similar to the first embodiment, the plate opening W[m2] is provided in the +X direction of the plate opening W[m1]. Also, the nozzle plate C[m2] is provided in the +X direction of the nozzle plate C[m1].

[0078] In the reference example, similar to the first embodiment, when the value m1 and the value m2 satisfy "m2 = 1 + m1", it is assumed that the plate opening interval U[m1][m2] becomes a constant interval. That is, in the reference example, it is assumed that the plate opening intervals U[1][2] to U[M - 1][M] are all equal. Also, in the reference example, it is assumed that the nozzle plate C[m] is fixed so that the relative positional relationship in the X-axis direction between the nozzle plate C[m] and the plate opening W[m] becomes constant. Specifically, it is assumed that the interval between the center of the nozzle plate C[m] and the center of the plate opening W[m] in the X-axis direction is constant. In this case, the nozzle row intervals D1[1][2] to D1[M - 1][M] and the nozzle row intervals D2[1][2] to D2[M - 1][M] are all equal.

[0079] In the reference example, the nozzle row interval D1[1][ma], D2[1][ma], and the plate opening interval U[1][ma] are all equal and are set to be natural number multiples of the interval G. Specifically, the nozzle row interval D1[1][ma], D2[1][ma], and the plate opening interval U[1][ma] are set to be ψ[ma] times the interval G. Here, the value ψ[ma] is a natural number larger than the value α. Also, in the reference example, similar to the first embodiment, the interval G is set to be M times the basic resolution unit ΔX, in other words, M times the interval R. That is, the nozzle row interval D1[1][ma] is set to be (M × ψ[ma]) times the basic resolution unit ΔX, in other words, (M × ψ[ma]) times the interval R. Also, the nozzle row interval DL is set to be a natural number multiple of the interval G. Specifically, the nozzle row interval DL is set to be α times the interval G. That is, the nozzle row interval DL is set to be (M × α) times the basic resolution unit ΔX, in other words, (M × α) times the interval R.

[0080] As described above, in the reference example, in the X-axis direction, the interval G, the nozzle row interval DL, and the nozzle row interval D1[1][ma] are set so as to satisfy G:DL:D1[1][ma]=M:M×α:M×ψ[ma]. That is, the nozzle row interval DL and the nozzle row interval D1[1][ma] are set to be natural number multiples of the interval G. For this reason, the ink ejected at the same timing every time the time t elapses from the nozzles N provided in the nozzle row L1[1], the nozzle row L2[1], and the nozzle row L1[ma] forms dots Dt on a plurality of rows separated from each other by the interval G in the X-axis direction on the recording paper PE. That is, in the reference example, the positions in the X-axis direction of the dots Dt formed by the ink ejected from the nozzles N belonging to the nozzle row L1[1], the dots Dt formed by the ink ejected from the nozzles N belonging to the nozzle row L2[1], and the dots Dt formed by the ink ejected from the nozzles N belonging to the nozzle row L1[ma] are the same positions in the X-axis direction. Therefore, when the scanning speed of the head module 2V is increased, in other words, when the interval G is increased, more specifically, when the value M is increased, the interval between the dots Dt formed from the nozzle row L1[1], the nozzle row L2[1], and the nozzle row L1[ma] increases in proportion to the value M, and the resolution in the X-axis direction decreases. Specifically, when M = 4, if the head module 2V according to the reference example forms dots Dt every time t while being scanned at a speed of moving by an interval G every time t, the minimum interval of the dots Dt formed by the head module 2V is, in the X-axis direction, equal to the interval G corresponding to the scanning speed, in other words, four times the basic resolution unit ΔX, that is, four times the interval R. That is, the head module 2V forms dots Dt at an interval four times the interval of the dots Dt formed by the head module 2 according to the first embodiment, which can form dots Dt in units of the basic resolution ΔX in the X-axis direction. That is, in the X-axis direction, while the minimum interval of the dots Dt formed by the head module 2 according to the first embodiment is the basic resolution unit ΔX, the minimum interval of the dots Dt formed by the head module 2V according to the reference example is four times the basic resolution unit ΔX, resulting in a decrease in resolution. Also, in the X-axis direction, when the interval of the dots Dt formed using the head module 2V according to the reference example is set to a value equal to the basic resolution unit ΔX, the speed at which the head module 2V is scanned needs to be set to a speed of moving by the basic resolution unit ΔX (interval R) every time t, in other words, to 1 / 4 of the interval G, which is slower than the scanning speed of the head module 2 according to the first embodiment.

[0081] In contrast, the head module 2 according to the first embodiment is set such that the interval G, the nozzle row interval DL, and the nozzle row interval D1[1][ma] satisfy G:DL:D1[1][ma]=M:M×α:M×β[ma]+γ[ma]. That is, the nozzle row interval DL is set to be a natural number multiple of the interval G. On the other hand, the nozzle row interval D1[1][ma] is set to an interval different from the natural number multiple of the interval G. For this reason, the ink ejected at the same timing every time the time t elapses from the nozzles N provided in the nozzle row L1[1] and the nozzle row L2[1] forms dots Dt on a plurality of raster rows spaced apart from each other by the interval G in the X-axis direction on the recording paper PE. On the other hand, the ink ejected at the same timing every time the time t elapses from the nozzles N provided in the (M - 1) nozzle rows L1[2] to L1[M] provided in the (M - 1) head chips 3[2] to 3[M] forms dots Dt on a raster row located between the plurality of raster rows formed by the ink ejected from the nozzles N provided in the nozzle row L1[1] and the nozzle row L2[1]. In addition, when the values ma1 and ma2 satisfy ma1≠ma2, since the values γ[ma1] and γ[ma2] satisfy 0<γ[ma1]≠γ[ma2]≦M - 1, in the X-axis direction, the ink ejected from the nozzles N provided in the nozzle row L1[ma1] provided at a position separated from the nozzle row L1[1] by (M×β[ma1]+γ[ma1])R forms dots Dt on a raster row at a different position in the X-axis direction from the ink ejected from the nozzles N provided in the nozzle row L1[ma2] provided at a position separated from the nozzle row L1[1] by (M×β[ma2]+γ[ma2])R. Therefore, even if the scanning speed of the head module 2 is made faster than a predetermined reference speed, by increasing the value M in accordance with the improvement of the scanning speed of the head module 2, the interval in the X-axis direction of the dots Dt formed from the nozzle row L1[1], the nozzle row L2[1], and the nozzle row L1[ma] can be made to form dots Dt on the recording paper PE without widening compared to the interval of the dots Dt formed when the scanning speed of the head module 2 is the predetermined reference speed.In other words, the inkjet printer 1 according to the first embodiment can increase the scanning speed of the head module 2 as the value M increases while maintaining the resolution in the X-axis direction. Specifically, when M = 4, in the X-axis direction, while scanning at a speed of moving by an interval G every time t, the moving speed of the head module 2 according to the first embodiment for forming dots Dt at an interval equal to the basic resolution unit ΔX is 4 times faster than the scanning speed of the head module 2V according to the reference example when making the interval of the dots Dt formed using the head module 2V according to the reference example equal to the basic resolution unit ΔX, based on the above correspondence relationship. That is, the inkjet printer 1 according to the first embodiment can shorten the printing time while maintaining the resolution in the X-axis direction with respect to the head module 2V according to the reference example. In other words, in the X-axis direction, the minimum interval of the dots Dt formed by the head module 2 according to the first embodiment, which forms dots Dt every time t while scanning at a speed of moving by an interval G every time t, becomes 1 / 4 of the minimum interval of the dots Dt formed by the head module 2V according to the reference example, based on the above correspondence relationship. That is, the inkjet printer 1 according to the first embodiment can improve the resolution while maintaining the scanning speed in the X-axis direction with respect to the head module 2V according to the reference example.

[0082] As described above, the head module 2 according to the first embodiment is a head module 2 having the X-axis direction as the main scanning direction, including a nozzle row L1[1] including nozzles N that eject ink, a nozzle row L2[1] including nozzles N that eject ink, and (M - 1) specific nozzle rows including nozzles N that eject ink. When the value ma is a natural number satisfying 2 ≤ ma ≤ M, the nozzle row interval DL between the nozzle row L1[1] and the nozzle row L2[1] in the X-axis direction, and the nozzle row interval D1[1][ma] between the nozzle row L1[1] and the nozzle row L1[ma] among the (M - 1) specific nozzle rows in the X-axis direction are a value M that is a natural number of 3 or more, a value α that is a natural number of 1 or more, a value β[ma] that is a natural number satisfying β[ma] > α, a value ma1 that is a natural number satisfying 2 ≤ ma1 ≤ M, and a value ma2 that is a natural number satisfying 2 ≤ ma2 ≤ M and ma1 ≠ ma2. When the value γ[ma] is a natural number satisfying 0 < γ[ma] ≤ M - 1 and γ[ma1] ≠ γ[ma2], it can be expressed as DL:D1[1][ma] = M×α:M×β[ma] + γ[ma], which is characterized by this. Therefore, in the first embodiment, for example, even when the nozzle row interval DL between the nozzle row L1[1] and the nozzle row L2[1] is defined as an interval that enables the nozzle row L2[1] to form a dot Dt at the same position as the dot Dt formed by the nozzle row L1[1] in the X-axis direction, the nozzle row interval D1[1][ma] between the nozzle row L1[1] and the nozzle row L1[ma] can be defined as an interval that enables the nozzle row L1[ma] to form a dot Dt at a position different from the dot Dt formed by the nozzle row L1[1] in the X-axis direction. For this reason, in the first embodiment, ink is ejected from each nozzle N every predetermined time t. When the nozzle row L1[1] forms a plurality of dots Dt at an interval G in the X-axis direction, it is possible to form a dot Dt by the nozzle row L1[ma] so as to complement the plurality of dots Dt in the X-axis direction between the plurality of dots Dt formed at the interval G by the nozzle row L1[1]. That is, according to the first embodiment, in the X-axis direction, which is the main scanning direction, it is possible to suppress the occurrence of dot Dt overlap and gaps and perform high-speed and high-resolution printing. Also, in the first embodiment, for example, even when the nozzle row interval D1[1][ma] between the nozzle row L1[1] and the nozzle row L1[ma] is defined as an interval such that the nozzle row L1[ma] can form dots Dt at positions different from the dots Dt formed by the nozzle row L1[1] in the X-axis direction, the nozzle row interval DL between the nozzle row L1[1] and the nozzle row L2[1] can be defined as an interval such that the nozzle row L2[1] can form dots Dt at the same positions as the dots Dt formed by the nozzle row L1[1] in the X-axis direction. Therefore, in the first embodiment, ink is ejected from each nozzle N every predetermined time t, and when the nozzle row L1[1] forms a plurality of dots Dt at an interval G in the X-axis direction, the nozzle row L2[1] can form dots Dt at the same positions as the plurality of dots Dt formed by the nozzle row L1[1] in the X-axis direction. That is, according to the first embodiment, it is possible to achieve high-speed and high-resolution printing in the X-axis direction, which is the main scanning direction, and at the same time, it is possible to achieve high-resolution printing in the Y-axis direction, which is the sub-scanning direction intersecting the main scanning direction. Note that in the first embodiment, the X-axis direction is an example of the "first direction", the head module 2 is an example of the "head module", the ink is an example of the "liquid", the nozzle N is an example of the "nozzle", the nozzle row L1[1] is an example of the "first nozzle row", the nozzle row L2[1] is an example of the "second nozzle row", the nozzle row interval DL is an example of the "interval P1", the nozzle row L1[ma] is an example of the "m-th specific nozzle row", the nozzle row interval D1[1][ma] is an example of the "interval PT[m]", β[ma] is an example of "βT[m]", and γ[ma] is an example of "γT[m]". Also, ma takes a value equal to m + 1, ma1 takes a value equal to m1 + 1, and ma2 takes a value equal to m2 + 1.

[0083] Regarding the nozzle row interval DL and the nozzle row interval D1[1][ma], there may be a value other than 1 that is a common divisor of the nozzle row interval DL and the nozzle row interval D1[1][ma], like the interval R in the first embodiment. A value that is the greatest common divisor of the nozzle row interval DL and the nozzle row interval D1[1][ma] is called value F1. When a value obtained by dividing the nozzle row interval DL by the value F1 is called value DLF1, and a value obtained by dividing the nozzle row interval D1[1][ma] by the value F1 is called value D1F1, if the value DLF1 and the value D1F1 satisfy DLF1:D1F1 = M×α:M×β[ma]+γ[ma], it may be regarded that for the nozzle row interval DL and the nozzle row interval D1[1][ma], it can be expressed as DL:D1[1][ma]=M×α:M×β[ma]+γ[ma]. Note that the value DLF1 and the value D1F1 are in a relatively prime relationship. Also, the nozzle row interval DL and the nozzle row interval D1[1][ma] may be in a relatively prime relationship. In other words, the value obtained by multiplying the value M and the value α, and the value obtained by multiplying the value M and the value β[ma] and adding γ[ma] may be in a relatively prime relationship.

[0084] Also, in the head module 2 according to the first embodiment, the nozzle row L1[1] includes nozzles N1[1]{j} that eject ink, the nozzle row L1[ma] includes nozzles N1[ma]{j} that eject ink, and the nozzles N1[1]{j} and the nozzles N1[ma]{j} are arranged at the same position in the Y-axis direction orthogonal to the X-axis direction. That is, the ink ejected from the nozzles N1[1]{j} and the nozzles N1[ma]{j} can form dots Dt at the same position in the Y-axis direction. Thereby, the head module 2 can improve the resolution in the X-axis direction. In the first embodiment, the nozzle N1[1]{j} is an example of the "first nozzle", the nozzle N1[ma]{j} is an example of the "specific nozzle", and the Y-axis direction is an example of the "second direction".

[0085] Also, in the head module 2 according to the first embodiment, the nozzle row L1[1] includes a plurality of nozzles N that eject ink, the nozzle row L2[1] includes a plurality of nozzles N that eject ink, and in the Y-axis direction, among the plurality of nozzles N included in the nozzle row L1[1], between two adjacent nozzles N, one nozzle N among the plurality of nozzles N included in the nozzle row L2[1] is provided. That is, in the Y-axis direction, the dot Dt formed by the nozzle N1[1]{j} and the nozzle N1[1]{j + 1} has the dot Dt formed by the nozzle N2[1]{j} located therebetween. Thereby, the head module 2 can improve the resolution in the Y-axis direction.

[0086] Also, the head module 2 according to the first embodiment includes a head chip 3[1] having a nozzle row L1[1] and a nozzle row L2[1], and (M - 1) specific head chips. Among the (M - 1) specific head chips, the head chip 3[ma] having the nozzle plate C[ma] includes the nozzle row L1[ma]. As described above, in the present embodiment, by setting the nozzle row interval DL between the nozzle row L1[1] and the nozzle row L2[1] and the nozzle row interval D1[1][ma] between the nozzle row L1[1] and the nozzle row L1[ma] to be expressible as DL:D1[1][ma]=M×α:M×β[ma]+γ[ma], in the X-axis direction which is the main scanning direction, while realizing high-speed and high-resolution printing, at the same time, in the Y-axis direction which is the sub-scanning direction intersecting the main scanning direction, high-resolution printing can be realized. However, if the value of M changes, the actual dimensions of the nozzle row spacing DL and the nozzle row spacing D1[1][ma] that satisfy this proportional formula will change. That is, it may be necessary to appropriately change the nozzle row spacing DL and the nozzle row spacing D1[1][ma] according to M. Also, there is a need for a head module as shown in the reference example, where the nozzle row spacing DL and all the nozzle row spacings D1[1][ma] are divisible by M. Therefore, instead of a structure in which all nozzle rows are formed on a single nozzle plate, a configuration in which a plurality of head chips each having one nozzle row are arranged on a fixing plate or a holder, specifically, a configuration in which the nozzle row L1[1], the nozzle row L2[1], and the nozzle row L1[ma] are formed on a single head chip is not used. Instead, it is desirable to have a configuration in which the head chip having the nozzle row L1[1], the head chip having the nozzle row L2[1], and the head chip having the nozzle row L1[ma] are arranged so that the nozzle row spacing DL and the nozzle row spacing D1[1][ma] can be freely changed. By doing so, various head modules can be realized only by changing the conditions of the process of arranging a plurality of head chips, and since a plurality of head chips can be made into a common platform, the manufacturing cost can be reduced. However, in a configuration in which a head module is composed of a plurality of head chips provided in units of nozzle rows, there are also problems such as an increase in the process of arranging a plurality of head chips and an increase in the influence of the deviation of the landing accuracy. Therefore, it is desirable to provide a plurality of nozzle rows on each head chip that is made into a platform. Although it is repetitive, in order to achieve the above-described effects of the present embodiment, the nozzle row interval DL between the nozzle row L1[1] and the nozzle row L2[1], and the nozzle row interval D1[1][ma] between the nozzle row L1[1] and the nozzle row L1[ma] may be expressed by a proportional formula of DL:D1[1][ma]=M×α:M×β[ma]+γ[ma]. Therefore, it is not always necessary for all of the nozzle row L1[1], the nozzle row L2[1], and the nozzle row L1[ma] to be provided on the same head chip, nor is it necessary for the nozzle row L1[1] and the nozzle row L1[2] to be provided on the same head chip 3 as in the present embodiment. That is, if either one of the nozzle row L2[2] or the nozzle row L1[ma] is provided on the same head chip as the nozzle row L1[1], and the other is provided on a different head chip, and a plurality of head chips are arranged so as to satisfy the relationship of the above-described proportional formula, it is possible to provide a plurality of nozzle rows on a platformed head chip and achieve the above-described effects. Here, the nozzle row L1[1] and the nozzle row L2[1] are nozzle rows that form dots in the same raster row in order to achieve high resolution in the Y-axis direction, or more specifically, as will be described in Embodiment 3 below, when ejection abnormality occurs in the nozzle N1[1][j] and dot omission occurs, the dots that were supposed to be ejected from the nozzle N1[1][j] are replaced with dots ejected from the nozzle N2[1][j]. Therefore, it is preferable to provide the nozzle row L1[1] and the nozzle row L2[1], which form dots in the same raster row, on the same head chip 3 because it is less likely to cause disturbance in the landing position of the dot Dt in the X-axis direction compared to the case where they are provided on different head chips 3, and the printing accuracy can be improved. Also, if the value of M is changed within the range where the nozzle row interval DL satisfies the above-described proportional formula, the value of the nozzle row interval D1[1][ma] may be changed so as to satisfy the above-described proportional formula. That is, if the nozzle rows L1[1] and L2[1] that form the same raster row are provided on the same head chip 3, the nozzle row interval D1[1][ma] can be changed so as to satisfy the above-described proportional formula only by adjusting the interval between the head chips 3 in the main scanning direction, and there is no need to change the internal structure of the head chip 3, which can reduce the manufacturing cost. In the first embodiment, the head chip 3[1] is an example of the "first head chip", and the head chip 3[ma] is an example of the "m-th specific head chip".

[0087] Also, in the head module 2 according to the first embodiment, the head chip 3[1] and the head chip 3[ma] have a common structure, which is characterized in that. Thereby, the manufacturing cost of the head chip can be reduced.

[0088] Also, in the head module 2 according to the first embodiment, the head chip 3[1] includes a nozzle plate C[1] provided with a nozzle row L1[1] and a nozzle row L2[1], and the head chip 3[ma] includes a nozzle plate C[ma] provided with a nozzle row L1[ma] among (M - 1) specific nozzle plates corresponding to (M - 1) specific head chips, which is characterized in that. Thereby, it becomes possible to improve the alignment accuracy of two nozzle rows capable of forming the dot Dt at the same position in the X-axis direction. In the first embodiment, the nozzle plate C[1] is an example of the "first nozzle plate", and the nozzle plate C[ma] is an example of the "m-th specific nozzle plate".

[0089] Further, in the head module 2 according to the first embodiment, the head chip 3[1] and the head chip 3[ma] are fixed, and a fixing plate 26 having a plate opening W for exposing at least the nozzle row L1[1] and the nozzle row L2[1] among the nozzle plates C[1], and at least the nozzle row L1[ma] among the nozzle plates C[ma], is provided. The head chip 3[1] and the head chip 3[ma] are fixed to the fixing plate 26 such that, when viewed in plan, the distance in the X-axis direction between the center of the head chip 3[1] and the center of the head chip 3[ma] is the nozzle row interval D1[1][ma]. In the X-axis direction, the center of the head chip 3[m] coincides with the center of the nozzle plate C[m] provided in the head chip 3[m]. Also, in the X-axis direction, the distance between the center of the nozzle plate C[m] and the center of the plate opening W[m] is constant. That is, the head chip 3[1] and the head chip 3[ma] are fixed to the fixing plate 26 such that, in the X-axis direction, the distance between their centers coincides with the plate opening interval U[1][ma] and also coincides with the nozzle row interval D1[1][ma]. Also, a plurality of head chips 3 are provided in the head module 2. Thus, when printing is performed using the head module 2 according to the first embodiment, compared with the case where the same printing is performed using a plurality of head modules such that the total number of nozzles N and nozzles in the head module 2 in the X-axis direction is equal, the scattering of the landing positions of the dots Dt is less likely to occur, and the printing accuracy is improved. Note that, in the first embodiment, the plate opening W and the plate opening W[m] are an example of an "opening", and the fixing plate 26 is an example of a "fixing plate".

[0090] Further, the head module 2 according to the first embodiment has a supply channel 251 for supplying ink to the head chip 3[1] and (M - 1) specific head chips, and the distance in the X-axis direction between the center of the head chip 3[1] and the center of the head chip 3[ma] in the X-axis direction is the nozzle row interval D1[1][ma], and includes a holder 25 that holds the head chip 3[1] and (M - 1) specific head chips. Thus, ink can be supplied to each head chip. In the first embodiment, the supply channel 251 is an example of a "supply channel", and the holder 25 is an example of a "holder". Also, in the first embodiment, although an example is shown in which ink is supplied to each head chip from different supply channels 251, the present invention is not limited to such a mode. The supply channel for supplying ink to each head chip may be a common channel having branches.

[0091] Further, the head module 2 according to the first embodiment includes an inlet 220 for introducing ink, and a distribution channel 221 that communicates with at least one specific nozzle among the nozzle N1[1]{j} and (M - 1) specific nozzles corresponding to (M - 1) specific nozzle rows, and distributes the ink introduced from the inlet 220 to the nozzle N1[1]{j} and at least one specific nozzle. Thus, the same ink can be supplied to a plurality of nozzles N. In the first embodiment, the inlet 220 is an example of an "inlet", and the distribution channel 221 is an example of a "distribution channel".

[0092] Further, the inkjet printer 1 according to the first embodiment includes the head module 2 according to the first embodiment, and a carriage 761 that reciprocates the head module 2 in the X-axis direction and the opposite direction of the X-axis direction. Thus, by performing a printing operation using the inkjet printer 1 including the head module 2 according to the first embodiment, occurrence of dot Dt overlap and gaps can be suppressed, and high-speed and high-resolution printing can be performed. In the first embodiment, the inkjet printer 1 is an example of a "liquid ejection device", and the carriage 761 is an example of a "carriage".

[0093] Also, in the inkjet printer 1 according to the first embodiment, the nozzle row L1[1] includes nozzles N1[1]{j} that eject ink, and the minimum interval in the X-axis direction between two dots Dt formed by the nozzles N1[1]{j} is an interval obtained by dividing the product of the value M and the value α by the nozzle row interval DL, and is an interval that is M times the basic resolution unit ΔX, which is an interval obtained by dividing the sum of the product of the value M and the value β[ma] and the value γ[ma] by the nozzle row interval D1[1][ma]. That is, the head module 2 mounted on the inkjet printer 1 according to the first embodiment is scanned in the X-axis direction at a speed that advances by M times the basic resolution unit ΔX, that is, an interval G, while forming two dots Dt from a specific nozzle N. Also, with respect to the minimum interval G between dots Dt formed by a specific nozzle N provided in the head module 2 in the X-axis direction, the nozzle row interval DL is set to an integer multiple of the interval G. Thereby, when forming dots Dt from the nozzles N1[1]{j} provided in the nozzle row L1[1] and the nozzles N2[1]{j} provided in the nozzle row L2[1] while the head module 2 is scanned in the X-axis direction, the dots Dt formed from the nozzles N1[1]{j} and the dots Dt formed from the nozzles N2[1]{j} can be formed at the same position in the X-axis direction. In the first embodiment, the dot Dt is an example of a "dot", and the basic resolution unit ΔX is an example of an "interval P0".

[0094] In the inkjet printer 1 according to the first embodiment, the nozzle row L2[1] includes nozzles N2[1]{j} that eject ink, each of the (M - 1) specific nozzle rows includes specific nozzles that eject ink, and the nozzle N1[1]{j}, the nozzle N2[1]{j}, and the (M - 1) specific nozzles corresponding to the (M - 1) specific nozzle rows can eject ink at the same timing. Thereby, it becomes possible to form the dots Dt at predetermined intervals. In the first embodiment, the nozzle N2[1]{j} is an example of the "second nozzle".

[0095] In the inkjet printer 1 according to the first embodiment, the nozzle row L1[1] includes nozzles N1[1]{j} that eject ink, the nozzle row L2[1] includes nozzles N2[1]{j} that eject ink, each of the (M - 1) specific nozzle rows includes specific nozzles that eject ink, and a first drive element provided for the nozzle N1[1]{j}, a second drive element provided for the nozzle N2[1]{j}, and (M - 1) specific drive elements provided for the (M - 1) specific nozzles corresponding to the (M - 1) specific nozzle rows are supplied with a common drive signal Com. Thereby, compared with a configuration in which separate drive signals Com are supplied to the first drive element, the second drive element, and the (M - 1) specific drive elements, it becomes possible to achieve miniaturization and cost reduction of the apparatus. In the first embodiment, the "first drive element" is exemplified by a piezoelectric element 331 corresponding to the nozzle N1[1]{j} provided on the nozzle plate C[1], the "second drive element" is exemplified by a piezoelectric element 332 corresponding to the nozzle N2[1]{j} provided on the nozzle plate C[1], and the "specific drive element" is exemplified by a piezoelectric element 331 corresponding to the nozzle N1[ma]{j} provided on the nozzle plate C[ma]. Also, the drive signal Com is an example of the "drive signal".

[0096] Further, in the inkjet printer 1 according to the first embodiment, each of the plurality of nozzles N included in the nozzle row L1[1], each of the plurality of nozzles N included in the nozzle row L2[1], and each of the plurality of nozzles N included in the (M - 1) specific nozzle rows discharges the same type of ink. That is, the same type of ink is discharged from each of the plurality of nozzles N provided at different positions in the Y-axis direction. Thereby, it becomes possible to achieve high resolution in the Y-axis direction.

[0097] Also, in the inkjet printer 1 according to the first embodiment, the nozzle row L1[1] includes nozzles N1[1]{j} that eject ink, the nozzle row L2[1] includes nozzles N2[1]{j} that eject ink, and each of the (M - 1) specific nozzle rows includes specific nozzles that eject ink. The nozzles N1[1]{j}, the nozzles N2[1]{j}, and the (M - 1) specific nozzles corresponding to the (M - 1) specific nozzle rows eject the same type of ink. The minimum interval in the X-axis direction between two dots Dt formed by the nozzles N1[1]{j} is an interval obtained by dividing the product of the value M and the value α by the nozzle row interval DL, and is also an interval that is M times the basic resolution unit ΔX, which is an interval obtained by dividing the sum of the product of the value M and the value β[ma] and the value γ[ma] by the nozzle row interval D1[1][ma]. In the Y-axis direction orthogonal to the X-axis direction, among the plurality of nozzles N included in the nozzle row L1[1], the interval between two adjacent nozzles N is n times the basic resolution unit ΔX. In the Y-axis direction orthogonal to the X-axis direction, the interval between the nozzles N1[1]{j} and the nozzles N2[1]{j} is the basic resolution unit ΔX. The value n is a natural number indicating the number of nozzle rows provided in the nozzle plate C[1] where the nozzle rows L1[1] and L2[1] are provided. This makes it possible to align the resolutions in both the main scanning direction and the sub-scanning direction. Note that the n nozzle rows are arranged shifted from each other in the Y-axis direction. That is, the n nozzle rows do not include nozzle rows arranged at the same position in the Y-axis direction. Also, for each of the n nozzle rows, the intervals in the Y-axis direction between adjacent nozzles N among the plurality of nozzles N constituting the nozzle row are equal. Also, in the Y-axis direction, between adjacent nozzles N among the plurality of nozzles N constituting any one of the n nozzle rows, one nozzle N of each of one or more other nozzle rows different from the said any one nozzle row among the n nozzle rows is positioned. And the n nozzle rows are arranged such that the value obtained by dividing the interval in the Y-axis direction between adjacent nozzles N among the plurality of nozzles N constituting the nozzle row by n corresponds to the interval R.

[0098] Further, the head module 2 according to the first embodiment is a head module 2 having the X-axis direction as the main scanning direction, and includes a nozzle N1[1]{j} that discharges ink, a nozzle N2[1]{j} that discharges ink, and a nozzle N1[2]{j} that discharges ink. The first dot formed by the ink discharged by the nozzle N1[1]{j} at the first timing and the second dot formed by the ink discharged by the nozzle N1[1]{j} at the second timing when the ink can be first discharged after the first timing are defined as the first interval in the X-axis direction. The interval in the X-axis direction between the third dot formed by the ink discharged by the nozzle N2[1]{j} at the first timing and the first dot is defined as the second interval. The interval in the X-axis direction between the fourth dot formed by the ink discharged by the nozzle N1[2]{j} at the first timing and the first dot is defined as the third interval. The nozzle N1[1]{j}, the nozzle N2[1]{j}, and the nozzle N1[2]{j} are provided such that the second interval is an integral multiple of the first interval and the third interval is an interval different from an integral multiple of the first interval. That is, the nozzle N1[1]{j} and the nozzle N2[1]{j} are set in an arrangement capable of forming the dot Dt at the same position in the X-axis direction, and the nozzle N1[1]{j}, the nozzle N2[1]{j}, and the nozzle N1[2]{j} are set in an arrangement capable of forming the dot Dt at different positions in the X-axis direction. Thereby, even when the printing speed is increased, it is possible to form the dot Dt without creating a gap in the X-axis direction, which is the main scanning direction. In the first embodiment, the nozzle N1[2]{j} is an example of the "third nozzle". Also, as an example, the "first interval" has the same value as the interval G, the "second interval" has the same value as the nozzle row interval DL, and the "third interval" has the same value as the nozzle row interval D1[1][2]. Further, the "first timing" is an arbitrary timing at which the nozzle N1[1]{j} discharges ink (for example, the timing when the time T becomes Tc + 1t), and the "second timing" is a timing that is t time later than the first timing (for example, the timing when the time T becomes Tc + 2t). Also, the "first dot" is the dot Dt formed by the ink discharged from the nozzle N1[1]{j} at the first timing, the "second dot" is the dot Dt formed by the ink discharged from the nozzle N1[1]{j} at the second timing, the "third dot" is the dot Dt formed by the ink discharged from the nozzle N2[1]{j} at the first timing, and the "fourth dot" is the dot Dt formed by the ink discharged from the nozzle N1[2]{j} at the first timing.

[0099] Moreover, the head module 2 according to the first embodiment is a head module 2 with the X-axis direction as the main scanning direction, including a nozzle row L1[1] including nozzles N1[1]{j} that eject ink, a nozzle row L2[1] including nozzles N2[1]{j} that eject ink, and a nozzle row L1[2] including nozzles N1[2]{j} that eject ink. The nozzle row interval DL between the nozzle row L1[1] and the nozzle row L2[1] in the X-axis direction, and the nozzle row interval D1[1][2] between the nozzle row L1[1] and the nozzle row L1[2] in the X-axis direction can be expressed as DL:D1[1][2]=M×α:M×β[2]+1, where M is a natural number of 3 or more, α is a natural number of 1 or more, and β[2] is a natural number satisfying β[2]>α. That is, when the head module 2 forms dots Dt at a predetermined interval while being scanned in the X-axis direction, the nozzle row interval D1[1][2] between the nozzle row L1[1] and the nozzle row L1[2] is set to a predetermined ratio with respect to the nozzle row interval DL between the nozzle row L1[1] and the nozzle row L2[1]. Thereby, by performing a printing operation using the head module 2 according to the first embodiment, it is possible to suppress the occurrence of dot Dt overlap and gaps in the X-axis direction, and perform high-speed and high-resolution printing. In the first embodiment, the nozzle row L1[2] is an example of the "third nozzle row", the nozzle row interval D1[1][2] is an example of the "interval P2", and β[2] is an example of "β".

[0100] Note that the nozzle row interval DL and the nozzle row interval D1[1][2] may be relatively prime to each other. In other words, the value obtained by multiplying the value M and the value α, and the value obtained by multiplying the value M and the value β[2] and adding 1 to the result may be relatively prime to each other.

[0101] Further, in the head module 2 according to the first embodiment, the nozzles N1[1]{j} and N1[2]{j} are arranged at the same position in the Y-axis direction orthogonal to the X-axis direction. That is, the ink ejected from the nozzles N1[1]{j} and N1[2]{j} can form dots Dt at the same position in the Y-axis direction. Thereby, the head module 2 can improve the resolution in the X-axis direction.

[0102] Further, the head module 2 according to the first embodiment includes a head chip 3[1] having nozzle rows L1[1] and L2[1], and a head chip 3[2] having a nozzle row L1[2]. That is, two nozzle rows for forming dots Dt at the same position in the X-axis direction are provided on one head chip 3. Thereby, the deviation of the landing position of the dot Dt in the X-axis direction is less likely to occur, and the printing accuracy is improved.

[0103] Further, in the head module 2 according to the first embodiment, the head chip 3[1] having nozzle rows L1[1] and L2[1] and the head chip 3[2] having a nozzle row L1[2] have a common structure. Thereby, the manufacturing cost of the head chip can be reduced.

[0104] Further, in the head module 2 according to the first embodiment, the head chip 3[1] having nozzle rows L1[1] and L2[1] includes a nozzle plate C[1] provided with the nozzle rows L1[1] and L2[1], and the head chip 3[2] having a nozzle row L1[2] includes a nozzle plate C[2] provided with the nozzle row L1[2]. Thereby, it becomes possible to improve the alignment accuracy of the two nozzle rows capable of forming dots Dt at the same position in the X-axis direction. Note that in the first embodiment, the nozzle plate C[2] is an example of the "second nozzle plate".

[0105] Also, in the head module 2 according to the first embodiment, a head chip 3[1] including a nozzle row L1[1] and a nozzle row L2[1] and a head chip 3[2] including a nozzle row L1[2] are fixed, and a fixing plate 26 having a plate opening W for exposing at least the nozzle row L1[1] and the nozzle row L2[1] of the nozzle plate C[1] and at least the nozzle row L1[2] of the nozzle plate C[2] is provided. The head chip 3[1] including the nozzle row L1[1] and the nozzle row L2[1] and the head chip 3[2] including the nozzle row L1[2] are fixed to the fixing plate 26 such that the distance in the X-axis direction between the center of the head chip 3[1] including the nozzle row L1[1] and the nozzle row L2[1] and the center of the head chip 3[2] including the nozzle row L1[2] becomes the nozzle row interval D1[1][2] when the fixing plate 26 is viewed in plan. In the X-axis direction, the center of the head chip 3[m] coincides with the center of the nozzle plate C[m] included in the head chip 3[m]. Also, in the X-axis direction, the distance between the center of the nozzle plate C[m] and the center of the plate opening W[m] is constant. That is, the head chip 3[1] including the nozzle row L1[1] and the nozzle row L2[1] and the head chip 3[2] including the nozzle row L1[2] are fixed to the fixing plate 26 such that the distance between their centers in the X-axis direction coincides with the plate opening interval U[1][2] and also coincides with the nozzle row interval D1[1][2]. Also, a plurality of head chips 3 are provided in the head module 2 at a constant interval. Thereby, when printing is performed using the head module 2 according to the first embodiment, compared with the case of performing the same printing using a plurality of head modules such that the total number of nozzles N and nozzles of the head module 2 in the X-axis direction is equal, the deviation of the landing position of the dots Dt is less likely to occur, and the printing accuracy is improved.

[0106] In addition, the head module 2 according to the first embodiment has a supply channel 251 for supplying ink to a head chip 3[1] including a nozzle row L1[1] and a nozzle row L2[1] and a head chip 3[2] including a nozzle row L1[2], and in the X-axis direction, the center of the head chip 3[1] including the nozzle row L1[1] and the nozzle row L2[1] and the center of the head chip 3[2] including the nozzle row L1[2] are spaced apart in the X-axis direction so as to be a nozzle row interval D1[1][2]. It is characterized by including a holder 25 that holds the head chip 3[1] including the nozzle row L1[1] and the nozzle row L2[1] and the head chip 3[2] including the nozzle row L1[2]. Thereby, ink can be supplied to each head chip.

[0107] In addition, the head module 2 according to the first embodiment includes an introduction port 220 for introducing ink, and a distribution channel 221 that communicates with the nozzles N1[1]{j} and N1[2]{j} and distributes the ink introduced from the introduction port 220 to the nozzles N1[1]{j} and N1[2]{j}. It is characterized by this. Thereby, the same ink can be supplied to a plurality of nozzles N.

[0108] In addition, in the inkjet printer 1 according to the first embodiment, the nozzles N1[1]{j}, N2[1]{j}, and N1[2]{j} can eject ink at the same timing. It is characterized by this. Thereby, it becomes possible to form dots Dt at a predetermined interval.

[0109] In addition, in the inkjet printer 1 according to the first embodiment, a common drive signal Com is supplied to a first drive element corresponding to the nozzle N1[1]{j}, a second drive element corresponding to the nozzle N2[1]{j}, and a third drive element corresponding to the nozzle N1[2]{j}. It is characterized by this. Thereby, it becomes possible to achieve miniaturization and cost reduction of the device. In the first embodiment, as an example, the "third drive element" is a piezoelectric element 331 corresponding to the nozzle N1[2]{j} provided on the nozzle plate C[2].

[0110] Also, in the inkjet printer 1 according to the first embodiment, the nozzles N1[1]{j}, N2[1]{j}, and N1[2]{j} are characterized by discharging the same type of ink. That is, the same type of ink is discharged from the nozzles N2[1]{j} and the nozzles N1[1]{j} and N1[2]{j} which are provided at different positions in the Y-axis direction. Thereby, it becomes possible to achieve higher resolution in the Y-axis direction.

[0111] Also, in the inkjet printer 1 according to the first embodiment, the nozzles N1[1]{j}, N2[1]{j}, and N1[2]{j} discharge the same type of ink. In the Y-axis direction orthogonal to the X-axis direction, among the plurality of nozzles N included in the nozzle row L1[1], the interval between two adjacent nozzles N is n times the basic resolution unit ΔX. In the Y-axis direction orthogonal to the X-axis direction, the interval between the nozzle N1[1]{j} and the nozzle N2[1]{j} is the basic resolution unit ΔX. The value n is a natural number indicating the number of nozzle rows provided in the nozzle plate C[1] where the nozzle row L1[1] and the nozzle row L2[1] are provided. Thereby, it becomes possible to align the resolutions in both the main scanning direction and the sub-scanning direction.

[0112] Note that the numerical values used in the above description according to the first embodiment are examples, and the following numerical values may be applied including the units. Basic resolution unit ΔX = Basic resolution unit ΔY = 1 / 600 inch, nozzle row interval DL = 24 / 600 inch, value α = 6, nozzle row interval D1[1][2] = 193 / 600 inch, value β[2] = 48, value γ[2] = 1, interval R = 1 / 600 inch, interval G = 4 / 600 inch, nozzle row interval D1[1][3] = 386 / 600 inch, value β[3] = 2β[2] = 96, value γ[3] = 2, nozzle row interval D1[1][4] = 579 / 600 inch, value β[4] = 3β[2] = 144, value γ[4] = 3.

[0113] 2. Second Embodiment Hereinafter, a second embodiment of the present invention will be described. In each of the embodiments exemplified below, for elements whose operations and functions are the same as those of the first embodiment, the reference numerals used in the description of the first embodiment are reused, and the detailed description of each is appropriately omitted.

[0114] The inkjet printer according to the second embodiment is different from the inkjet printer 1 according to the first embodiment in that it includes a plurality of ink cartridges 4 corresponding to a plurality of colors of ink and a head module 2QS corresponding to a plurality of colors of ink, and in that it includes one ink cartridge 4 and a head module 2. The head module 2QS includes a head chip group 300Q and a head chip group 300S. When the head chip group 300Q and the head chip group 300S are not distinguished, they are referred to as the head chip group 300. In the present embodiment, each head chip group 300 includes M head chips 3, as in the first embodiment. Also, in the present embodiment, each head chip 3 includes a nozzle row L1 composed of J nozzles N1 and a nozzle row L2 composed of J nozzles N2, as in the first embodiment.

[0115] Specifically, in the second embodiment, as an example, it is assumed that two ink cartridges 4, namely an ink cartridge 4Q (not shown) storing yellow ink and an ink cartridge 4S (not shown) storing cyan ink, are stored in the carriage 761. Also, the inkjet printer according to the second embodiment includes two head chip groups 300, namely a head chip group 300Q provided corresponding to the ink cartridge 4Q and a head chip group 300Q provided corresponding to the ink cartridge 4S.

[0116] Among these, the head chip group 300Q includes M head chips 3Q (not shown). The head chip 3Q includes 2J nozzles NQ that eject yellow ink. Specifically, the head chip 3Q includes a nozzle plate CQ in which a nozzle row LQ1 composed of J nozzles NQ1 and a nozzle row LQ2 composed of J nozzles NQ2 are formed.

[0117] Also, the head chip group 300S includes M head chips 3S (not shown). The head chip 3S includes 2J nozzles NS that eject cyan ink. Specifically, the head chip 3S includes a nozzle plate CS in which a nozzle row LS1 composed of J nozzles NS1 and a nozzle row LS2 composed of J nozzles NS2 are formed.

[0118] FIG. 9 is an explanatory diagram showing the positional relationship between the M nozzle plates CQ included in the head chip group 300Q, the M nozzle plates CS included in the head chip group 300S, and the fixing plate 26. Note that FIG. 9 shows various positional relationships when the head chip group 300Q and the head chip group 300S are viewed in perspective from the -Z direction to the +Z direction. Also, hereinafter, the case of M = 2 will be exemplified and described.

[0119] As shown in FIG. 9, M nozzle plates CQ[1] to CQ[M] and M nozzle plates CS[1] to CS[M] are fixed to the fixing plate 26. In the present embodiment, it is assumed that the M nozzle plates CQ[1] to CQ[M] and the M nozzle plates CS[1] to CS[M] all have a common structure. Hereinafter, among the M nozzle plates CQ[1] to CQ[M], the m-th nozzle plate CQ counted from the -X direction side to the +X direction side is referred to as nozzle plate CQ[m]. Also, among the M nozzle plates CS[1] to CS[M], the m-th nozzle plate CS counted from the -X direction side to the +X direction side is referred to as nozzle plate CS[m]. In this embodiment, the value m is an arbitrary natural number satisfying 1 ≦ m ≦ M. Note that the nozzle plate CQ[m] is fixed to the head chip 3Q[m], and the nozzle plate CS[m] is fixed to the head chip 3S[m]. In this embodiment, the nozzle plate CQ[1] is fixed to the head chip 3Q[1], and the nozzle plate CS[1] is fixed to the head chip 3S[1]. Also, the nozzle plate CQ[2] is fixed to the head chip 3Q[2], and the nozzle plate CS[2] is fixed to the head chip 3S[2].

[0120] In this embodiment, the nozzle plate CQ[m2] is located in the +X direction of the nozzle plate CQ[m1]. Here, as described above, the values m1 and m2 are arbitrary natural numbers satisfying 1 ≦ m1 < m2 ≦ M. Also, in this embodiment, the nozzle plate CS[m2] is located in the +X direction of the nozzle plate CS[m1]. Also, in this embodiment, the nozzle plate CS[m] is located in the +X direction of the nozzle plate CQ[m]. Since this embodiment assumes the case where M = 2, the values m1 and m2 satisfy 1 ≦ m1 < m2 ≦ 2. That is, in this embodiment, the case where m1 = 1 and m2 = 2 is assumed.

[0121] Hereinafter, the nozzle row LQ1 provided on the nozzle plate CQ[m] is referred to as nozzle row LQ1[m], the nozzle row LQ2 provided on the nozzle plate CQ[m] is referred to as nozzle row LQ2[m], the nozzle row LS1 provided on the nozzle plate CS[m] is referred to as nozzle row LS1[m], and the nozzle row LS2 provided on the nozzle plate CS[m] is referred to as nozzle row LS2[m]. In the present embodiment, the interval in the X-axis direction between nozzle rows LQ1[m] and nozzle row LQ2[m] is the nozzle row interval DL, and the interval in the X-axis direction between nozzle rows LS1[m] and nozzle row LS2[m] is the nozzle row interval DL. Further, hereinafter, the interval in the X-axis direction between nozzle rows LQ1[m1] and nozzle row LQ1[m2] is represented as nozzle row interval DQ1[m1][m2], the interval in the X-axis direction between nozzle rows LQ2[m1] and nozzle row LQ2[m2] is represented as nozzle row interval DQ2[m1][m2], the interval in the X-axis direction between nozzle rows LS1[m1] and nozzle row LS1[m2] is represented as nozzle row interval DS1[m1][m2], and the interval in the X-axis direction between nozzle rows LS2[m1] and nozzle row LS2[m2] is represented as nozzle row interval DS2[m1][m2]. Also, in the present embodiment, the interval in the X-axis direction between nozzle row LQ1[m] and nozzle row LS1[m], and the interval in the X-axis direction between nozzle row LQ2[m] and nozzle row LS2[m] are both the interval DQS.

[0122] Also, hereinafter, among the J nozzles N included in the nozzle row LQ1[m], the j-th nozzle N from the -Y direction side is referred to as nozzle NQ1[m]{j}, and among the J nozzles N included in the nozzle row LQ2[m], the j-th nozzle N from the -Y direction side is referred to as nozzle NQ2[m]{j}, among the J nozzles N included in the nozzle row LS1[m], the j-th nozzle N from the -Y direction side is referred to as nozzle NS1[m]{j}, and among the J nozzles N included in the nozzle row LS2[m], the j-th nozzle N from the -Y direction side is referred to as nozzle NS2[m]{j}. In the present embodiment, nozzle NQ1[m]{j} is located on the -Y direction side with respect to nozzle NQ2[m]{j}, the interval in the Y-axis direction between nozzle NQ1[m]{j} and nozzle NQ2[m]{j} is interval R, and the interval in the Y-axis direction between nozzle NQ2[m]{j} and nozzle NQ1[m]{j + 1} is interval R. Also, in the present embodiment, nozzle NS1[m]{j} is located on the -Y direction side with respect to nozzle NS2[m]{j}, the interval in the Y-axis direction between nozzle NS1[m]{j} and nozzle NS2[m]{j} is interval R, and the interval in the Y-axis direction between nozzle NS2[m]{j} and nozzle NS1[m]{j + 1} is interval R.

[0123] The fixed plate 26 is provided with M plate openings WQ[1] to WQ[M] that correspond one-to-one with M nozzle plates CQ[1] to CQ[M], and M plate openings WS[1] to WS[M] that correspond one-to-one with M nozzle plates CS[1] to CS[M]. The head chip 3Q[m] is fixed to the fixed plate 26 such that the nozzle rows LQ1[m] and LQ2[m] provided on the nozzle plate CQ[m] included in the head chip 3Q[m] are exposed from the plate opening WQ[m] provided in the fixed plate 26. The head chip 3S[m] is fixed to the fixed plate 26 such that the nozzle rows LS1[m] and LS2[m] provided on the nozzle plate CS[m] included in the head chip 3S[m] are exposed from the plate opening WS[m] provided in the fixed plate 26. In this embodiment, it is assumed that the nozzle plates CQ[1] to CQ[M] and the nozzle plates CS[1] to CS[M] are all fixed at the same position in the Y-axis direction. That is, the nozzle NQ1[m1]{j}, the nozzle NQ1[m2]{j}, the nozzle NS1[m1]{j}, and the nozzle NS1[m2]{j} are arranged at the same position in the Y-axis direction. Also, the plate opening WQ[m2] is provided in the +X direction of the plate opening WQ[m1]. Also, the plate opening WS[m2] is provided in the +X direction of the plate opening WS[m1].

[0124] Hereinafter, the interval in the X-axis direction between the center of the plate opening WQ[m1] and the center of the plate opening WQ[m2] is referred to as the plate opening interval UQ[m1][m2], and the interval in the X-axis direction between the center of the plate opening WS[m1] and the center of the plate opening WS[m2] is referred to as the plate opening interval US[m1][m2]. In this embodiment, it is assumed that when the values m1 and m2 satisfy "m2 = 1 + m1", the plate opening interval UQ[m1][m2] and the plate opening interval US[m1][m2] are at a constant interval. That is, in this embodiment, it is assumed that the plate opening interval UQ[1][2] and the plate opening interval US[1][2] are both equal. In addition, in the present embodiment, it is assumed that the intervals in the X-axis direction between the center of the nozzle plate CQ[m] and the center of the plate opening WQ[m], and between the center of the nozzle plate CS[m] and the center of the plate opening WS[m] are constant. Also, in the present embodiment, the interval in the X-axis direction between the plate opening WQ[m] and the plate opening WS[m] is the interval UQS. In the present embodiment, the interval UQS is equal to the interval DQS.

[0125] FIGS. 10 to 12 are explanatory diagrams illustrating the positional relationship between the operations of the head chip groups 300Q and 300S and the dots Dt formed by the head chip groups 300Q and 300S when performing a printing operation using the head module 2QS shown in FIG. 9.

[0126] Also, in FIGS. 10 to 12, among the total of 4×M×J nozzles N provided in the head module 2QS, M nozzles NQ1[1]{j} to NQ1[M]{j}, M nozzles NQ1[1]{j + 1} to NQ1[M]{j + 1}, M nozzles NQ2[1]{j} to NQ2[M]{j}, M nozzles NQ2[1]{j + 1} to NQ2[M]{j + 1}, M nozzles NS1[1]{j} to NS1[M]{j}, M nozzles NS1[1]{j + 1} to NS1[M]{j + 1}, M nozzles NS2[1]{j} to NS2[M]{j}, and M nozzles NS2[1]{j + 1} to NS2[M]{j + 1} are focused on to explain the printing operation. As described above, in the present embodiment, the case where M = 2 is assumed. Therefore, in FIGS. 10 to 12, among the total of 8×J nozzles N provided in the head module 2QS, two nozzles NQ1[1]{j} to NQ1[2]{j}, two nozzles NQ1[1]{j + 1} to NQ1[2]{j + 1}, two nozzles NQ2[1]{j} to NQ2[2]{j}, two nozzles NQ2[1]{j + 1} to NQ2[2]{j + 1}, two nozzles NS1[1]{j} to NS1[2]{j}, two nozzles NS1[1]{j + 1} to NS1[2]{j + 1}, two nozzles NS2[1]{j} to NS2[2]{j}, and two nozzles NS2[1]{j + 1} to NS2[2]{j + 1} are shown.

[0127] Also, in FIGS. 10 to 12, similar to FIGS. 6 to 8, the formation process of the dot Dt when the head module 2QS discharges ink while moving in the +X direction is illustrated. Among these, FIG. 10 illustrates the positional relationship between the head module 2QS and the dot Dt when the time T is from Tc + 1t to Tc + 4t. Also, FIG. 11 illustrates the positional relationship between the head module 2QS and the dot Dt when the time T is from Tc + 5t to Tc + 8t. Also, FIG. 12 illustrates the positional relationship between the head module 2QS and the dot Dt when the time T is from Tc + 9t to Tc + 12t. Also, for clarification, the positions of the nozzle plates CQ[m] and CS[m] in the X-axis direction at each time are illustrated below the rectangular dashed line indicating the head module 2QS using a rectangular dashed line having the same height as the interval R. Also, for convenience of illustration, in FIGS. 10 to 12, the dot Dt is a square having a width equal to the interval R in the X-axis direction and the Y-axis direction, and all the dots Dt are regarded as having the same shape. In FIGS. 10 to 12, among the plurality of dots Dt formed by the head module 2QS, the dot Dt formed by the yellow ink ejected from the nozzle NQ provided in the head chip group 300Q is referred to as dot Dty, and the dot Dt formed by the cyan ink ejected from the nozzle NS provided in the head chip group 300S is referred to as dot Dtc. Also, in FIGS. 10 to 12, the green dot Dt obtained as a result of the yellow dot Dty and the cyan dot Dtc being formed at the same position is referred to as dot Dtg. As shown in FIGS. 10 to 12, the position of dot Dty is indicated by the region hatched most thinly, the position of dot Dtg is indicated by the region hatched most thickly, and the position of dot Dtc is indicated by the region hatched with a density intermediate between the hatching of the region indicating the position of dot Dty and the hatching of the region indicating the position of dot Dtg. More specifically, in the dot Dt forming process at time T = Tc + 12t shown in FIG. 12, the dot Dt formed at the position where the X-axis coordinate AX is 8 is dot Dty, the dot Dt formed at the position where the X-axis coordinate AX is 21 is dot Dtg, and the dot Dt formed at the position where the X-axis coordinate AX is 36 is dot Dtc.

[0128] In the second embodiment, each of the plurality of nozzles N provided in the head module 2QS ejects the first ink at time T = Tc + 1t to form a dot Dt on the recording paper PE, and thereafter, a new dot Dt is formed every time the time t elapses. For convenience of illustration, similar to FIGS. 6 to 8, a so-called solid printing process in which ink is ejected from all the nozzles N provided in the head module 2QS at the same timing to form dots Dt without gaps is illustrated, but it is not limited thereto. The head module 2QS may eject ink from some of the nozzles N to form dots Dt.

[0129] In the head module 2QS, various dimensions and arrangements in the X-axis direction are set based on the basic resolution unit ΔX in the X-axis direction. Also, in the head module 2QS, various dimensions and arrangements in the Y-axis direction are set based on the basic resolution unit ΔY in the Y-axis direction. In the second embodiment, as an example, a case where the basic resolution unit ΔX is equal to the basic resolution unit ΔY is assumed. Also, in this embodiment, as an example, a case where the interval R is set to be equal to the basic resolution unit ΔX and the basic resolution unit ΔY is assumed.

[0130] Also, the scanning speed of the head module 2QS in the X-axis direction is set based on the basic resolution unit ΔX. For example, after the time T = Tc + 1t, the head module 2QS is scanned at a speed of advancing by an interval G set based on the basic resolution unit ΔX every time the time t elapses. In this embodiment, the interval G is set to be a natural number multiple of the basic resolution unit ΔX. Specifically, the interval G is set to be M times the basic resolution unit ΔX, in other words, M times the interval R. That is, in this embodiment, G = MR. More specifically, in this embodiment, as described above, M = 2. Therefore, in this embodiment, the scanning speed of the head module 2QS is set such that G = 2R.

[0131] In this embodiment, the nozzle row interval DL is set based on the basic resolution unit ΔX in the X-axis direction. Specifically, the nozzle row interval DL is set to be a natural number multiple of the basic resolution unit ΔX. Also, the nozzle row interval DL is set to be a natural number multiple of the interval G. Specifically, the nozzle row interval DL is set to be α times the interval G. That is, the nozzle row interval DL is set to be (M×α) times the basic resolution unit ΔX, in other words, (M×α) times the interval R. That is, DL = (M×α)×R. Here, the value α is a natural number of 1 or more. In addition, in the present embodiment, the nozzle row interval DQ1[1][ma] is determined based on the basic resolution unit ΔX in the X-axis direction. As described above, the value ma is an arbitrary natural number satisfying 2 ≦ ma ≦ M. Specifically, the nozzle row interval DQ1[1][ma] is set to a natural number multiple of the basic resolution unit ΔX. More specifically, assuming the case where M = 2 in the present embodiment, the value ma satisfies ma = 2. That is, the nozzle row interval DQ1[1][2] is set to a natural number multiple of the basic resolution unit ΔX. Also, the nozzle row interval DQ1[1][ma] is set to an interval different from the natural number multiple of the interval G. Specifically, the nozzle row interval DQ1[1][ma] is set to an interval obtained by adding β[ma] times the interval G and γ[ma] times the interval R. That is, the nozzle row interval DQ1[1][ma] is set to (M × β[ma] + γ[ma]) times the basic resolution unit ΔX, in other words, (M × β[ma] + γ[ma]) times the interval R. That is, DQ1[1][ma] = (M × β[ma] + γ[ma]) × R. As described above, the value ma is an arbitrary natural number satisfying 2 ≦ ma ≦ M. Also, the value β[ma] is a natural number satisfying α < β[ma]. Also, the value γ[ma] is a natural number satisfying 1 ≦ γ[ma] ≦ M - 1. Also, when M ≧ 3 is satisfied, the value γ[ma] satisfies γ[ma1] ≠ γ[ma2] when natural numbers ma1 and ma2 satisfy 2 ≦ ma1 < ma2 ≦ M. That is, in the present embodiment, assuming the case where M = 2, ma = 2, β[ma] = β[2], γ[ma] = γ[2] = 1, and DQ1[1][ma] = DQ1[1][2] = (2 × β[2] + γ[2]) × R = (2 × β[2] + 1) × R holds. In addition, in the present embodiment, the nozzle row interval DS1[1][ma] is determined based on the basic resolution unit ΔX in the X-axis direction. Also, the nozzle row interval DS1[1][ma] is set to the same interval as the nozzle row interval DQ1[1][ma]. That is, the nozzle row interval DS1[1][ma] is set to (M×β[ma]+γ[ma]) times the basic resolution unit ΔX, in other words, (M×β[ma]+γ[ma]) times the interval R. That is, DS1[1][ma]=(M×β[ma]+γ[ma])×R. Also, as described above, assuming the case where M = 2, ma = 2, β[ma]=β[2], γ[ma]=γ[2]=1, DS1[1][ma]=DS1[1][2]=(2×β[2]+γ[2])×R=(2×β[2]+1)×R holds. In addition, in the present embodiment, the interval DQS is set to a natural number multiple of the basic resolution unit ΔX. Also, the interval DQS is set to a natural number multiple of the interval G. Specifically, the interval DQS is set to ω times the interval G. That is, the interval DQS is set to (M×ω) times the basic resolution unit ΔX, in other words, (M×ω) times the interval R. That is, DQS=(M×ω)×R. Here, the value ω is a natural number that satisfies β[ma]<ω.

[0132] As described above, in the present embodiment, the nozzle row interval DL, the nozzle row intervals DQ1[1][ma] and DS1[1][ma], and the interval DQS are set so as to satisfy DL:DQ1[1][ma](=DS1[1][ma]):DQS=ΔX×M×α:ΔX×(M×β[ma]+γ[ma]):ΔX×M×ω=M×α:M×β[ma]+γ[ma]:M×ω. In this embodiment, it is assumed that M = 2 and ma = 2. Therefore, in this embodiment, γ[ma]=1, and M×α, M×β[ma], and M×ω are even numbers. In other words, in this embodiment, M×α is an even number, M×β[ma]+γ[ma] is an odd number, and M×ω is an even number. Thus, in this embodiment, the nozzle row interval DL, the nozzle row intervals DQ1[1][ma] and DS1[1][ma], and the interval DQS are set to satisfy DL:DQ1[1][ma](=DS1[1][ma]):DQS = E1:O1:E2. Here, the value E1 is a positive even number, the value O1 is a positive odd number satisfying O1>E1, and the value E2 is a positive even number satisfying E2>O1.

[0133] In FIGS. 10 to 12, the position of the nozzle NQ1[1]{j} in the X-axis direction at time T = Tc + 1t is AX = 0. Therefore, the nozzle NQ1[1]{j} can form a dot Dty at AX = 2k - 2 at time T = Tc + kt. In other words, the nozzle NQ1[1]{j} can form a dot Dty at AX = 2×k1. Here, the variable k is a natural number of 1 or more. Also, in this embodiment, the variable k1 is an integer satisfying k1 = k - 1. Also, in FIGS. 10 to 12, it is assumed that α = 1. The nozzle NQ2[1]{j} is provided at a position shifted from the nozzle NQ1[1]{j} by an interval equal to the nozzle row interval DL in the +X direction. Also, in this embodiment, since M = 2, the nozzle row interval DL is set to (M×α) times the basic resolution unit ΔX, in other words, (M×α) times the interval R, that is, 2 times the interval R. Therefore, the nozzle NQ2[1]{j} can form a dot Dty at AX = 2k at time T = Tc + kt. In other words, the nozzle NQ2[1]{j} can form a dot Dty at AX = 2×(k1 + 1).

[0134] Also, in FIGS. 10 to 12, the position of nozzle NQ1[2]{j} in the X-axis direction at time T = Tc + 1t is AX = 7. Since the position of nozzle NQ1[1]{j} in the X-axis direction at time T = Tc + 1t is AX = 0, in FIGS. 10 to 12, DQ1[1][2] = (2×β[2] + γ[2])R = 7R can be expressed. As described above, since γ[2] = 1, in FIGS. 10 to 12, when ma = 2, β[2] = 3. And since nozzle NQ1[2]{j} is provided at a position moved by AX = +7 from nozzle NQ1[1]{j}, at time T = Tc + kt, dot Dty can be formed for AX = 2k + 5. In other words, nozzle NQ1[2]{j} can form dot Dty for AX = 2×k2 + 1. In this embodiment, the variable k2 is an integer that satisfies k2 = k + 2. Also, in FIGS. 10 to 12, since nozzle NQ2[2]{j} is provided at a position moved by an interval equal to the nozzle row interval DL, i.e., 2R, in the +X direction from nozzle NQ1[2]{j}, at time T = Tc + kt, dot Dty can be formed for AX = 2k + 7. In other words, nozzle NQ2[2]{j} can form dot Dty for AX = 2×(k2 + 1) + 1.

[0135] As described above, nozzle NQ1[1]{j} can form dot Dty for AX = 2×k1, and nozzle NQ1[2]{j} can form dot Dty for AX = 2×k2 + 1. Therefore, in FIGS. 10 to 12, with the two nozzles NQ1[1]{j} and NQ1[2]{j}, it is possible to form a plurality of dots Dty in the X-axis direction without overlap at the basic resolution unit ΔX (interval R).

[0136] Also, in FIGS. 10 to 12, the position of nozzle NS1[1]{j} in the X-axis direction at time T = Tc + 1t is AX = 12. Therefore, nozzle NS1[1]{j} can form dot Dtc for AX = 2k + 10 at time T = Tc + kt. In other words, nozzle NS1[1]{j} can form dot Dtc for AX = 2 × k3. In this embodiment, variable k3 is an integer that satisfies k3 = k + 5. Also, in FIGS. 10 to 12, since nozzle NS2[1]{j} is provided at a position shifted by an interval equal to the nozzle row interval DL, i.e., 2R, in the +X direction from NS1[1]{j}, at time T = Tc + kt, it can form dot Dtc for AX = 2k + 12. In other words, nozzle NS2[1]{j} can form dot Dty for AX = 2 × (k3 + 1).

[0137] Also, in FIGS. 10 to 12, the position of nozzle NS1[2]{j} in the X-axis direction at time T = Tc + 1t is AX = 19. That is, since the positional relationship between nozzle NS1[1]{j} and nozzle NS1[2]{j} is the same as the positional relationship between nozzle NQ1[1]{j} and nozzle NQ1[2]{j} described above, in FIGS. 10 to 12, β[2] = 3 and γ[2] = 1. And nozzle NS1[2]{j} can form dot Dtc for AX = 2k + 17 at time T = Tc + kt. In other words, nozzle NS1[2]{j} can form dot Dtc for AX = 2 × k4 + 1. In this embodiment, variable k4 is an integer that satisfies k4 = k + 8. Also, in FIGS. 10 to 12, since nozzle NS2[2]{j} is provided at a position shifted by an interval equal to the nozzle row interval DL, i.e., 2R, in the +X direction from nozzle NS1[2]{j}, at time T = Tc + kt, it can form dot Dtc for AX = 2k + 19. In other words, nozzle NS2[2]{j} can form dot Dtc for AX = 2 × (k4 + 1) + 1.

[0138] As described above, the nozzle NS1[1]{j} can form the dot Dtc for AX = 2×k3, and the nozzle NS1[2]{j} can form the dot Dtc for AX = 2×k4 + 1. Therefore, in FIGS. 10 to 12, two nozzles NS1[1]{j} and NS1[2]{j} can form a plurality of dots Dtc in the X-axis direction without overlap at the basic resolution unit ΔX (interval R).

[0139] Thus, according to this embodiment, the head module 2QS can form the dot Dty and the dot Dtc at the basic resolution unit ΔX in the X-axis direction. That is, according to this embodiment, the head module 2QS can form a plurality of dots Dt in the X-axis direction without overlap at the basic resolution unit ΔX (interval R) to form the dot Dtg. That is, according to this embodiment, it is possible to form a plurality of dots Dtg on the recording paper PE such that the interval of the dots Dtg in the X-axis direction is equal to the interval of the dots Dtg in the Y-axis direction.

[0140] As described above, according to this embodiment, the head module 2QS can form a plurality of types of dots Dt at the interval R in the X-axis direction. As described above, since the interval R is equal to the basic resolution unit ΔX and the basic resolution unit ΔY, according to this embodiment, the head module 2QS can form a plurality of types of dots Dt on the recording paper PE such that the interval of the dots Dt in the X-axis direction and the interval of the dots Dt in the Y-axis direction are both equal to the basic resolution unit.

[0141] Also, in this embodiment, similar to the first embodiment, by using two nozzle arrays provided at different positions in the Y-axis direction, a plurality of types of dots Dt can be formed at different positions in the Y-axis direction.

[0142] Also, in this embodiment, similar to the first embodiment, by using two nozzle arrays capable of forming dots Dt at different positions in the X-axis direction, a plurality of types of dots Dt can be formed at different positions in the X-axis direction.

[0143] As described above, the head module 2QS according to the second embodiment is a head module 2QS having the X-axis direction as the main scanning direction, including a nozzle array LQ1[1] including nozzles NQ1[1]{j} that eject ink, a nozzle array LQ2[1] including nozzles NQ2[1]{j} that eject ink, and a nozzle array LQ1[2] including nozzles NQ1[2]{j} that eject ink. The nozzle array pitch DL between the nozzle array LQ1[1] and the nozzle array LQ2[1] in the X-axis direction and the nozzle array pitch DQ1[1][2] between the nozzle array LQ1[1] and the nozzle array LQ1[2] in the X-axis direction can be expressed as DL:DQ1[1][2]=E1:O1 by a positive even value E1 and a positive odd value O1 that satisfies O1>E1. That is, when the head module 2QS forms dots Dty at a predetermined interval while being scanned in the X-axis direction, the nozzle array pitch DQ1[1][2] between the nozzle array LQ1[1] and the nozzle array LQ1[2] is set to a predetermined ratio with respect to the nozzle array pitch DL between the nozzle array LQ1[1] and the nozzle array LQ2[1]. Thereby, by performing a printing operation using the head module 2QS according to the second embodiment, it is possible to suppress the occurrence of dot Dty overlap and gaps in the X-axis direction and perform high-speed and high-resolution printing. In the second embodiment, the X-axis direction is an example of the "first direction", the head module 2QS is an example of the "head module", the ink is an example of the "liquid", the nozzle NQ1[1]{j} is an example of the "first nozzle", the nozzle row LQ1[1] is an example of the "first nozzle row", the nozzle NQ2[1]{j} is an example of the "second nozzle", the nozzle row LQ2[1] is an example of the "second nozzle row", the nozzle NQ1[2]{j} is an example of the "third nozzle", the nozzle row LQ1[2] is an example of the "third nozzle row", the nozzle row interval DL is an example of the "interval P1", and the nozzle row interval DQ1[1][2] is an example of the "interval P2".

[0144] Regarding the nozzle row interval DL and the nozzle row interval DQ1[1][2], there may be a value other than 1 that is a common divisor of the nozzle row interval DL and the nozzle row interval DQ1[1][2]. When the value that is the greatest common divisor of the nozzle row interval DL and the nozzle row interval DQ1[1][2] is called value F2, the value obtained by dividing the nozzle row interval DL by value F2 is called value DLF2, and the value obtained by dividing the nozzle row interval DQ1[1][2] by value F2 is called value D1F2, if the value DLF2 and the value D1F2 satisfy DLF2:D1F2 = E1:O1, it may be regarded that the nozzle row interval DL and the nozzle row interval DQ1[1][2] can be expressed as DL:DQ1[1][2] = E1:O1. Note that the value DLF2 and the value D1F2 are in a relatively prime relationship. Also, the nozzle row interval DL and the nozzle row interval DQ1[1][2] may be in a relatively prime relationship. In other words, the value E1 and the value O1 may be in a relatively prime relationship.

[0145] Further, in the head module 2QS according to the second embodiment, the nozzle NQ1[1]{j} and the nozzle NQ1[2]{j} are arranged at the same position in the Y-axis direction orthogonal to the X-axis direction. That is, the ink ejected from the nozzle NQ1[1]{j} and the nozzle NQ1[2]{j} can form dots Dt at the same position in the Y-axis direction. Thereby, the head module 2QS can improve the resolution in the X-axis direction. In the second embodiment, the Y-axis direction is an example of the "second direction".

[0146] Also, in the head module 2QS according to the second embodiment, the nozzle row LQ1[1] includes a plurality of nozzles N that eject ink, the nozzle row LQ2[1] includes a plurality of nozzles NQ that eject ink, and in the Y-axis direction, among the plurality of nozzles NQ included in the nozzle row LQ1[1], one nozzle NQ among the plurality of nozzles NQ included in the nozzle row LQ2[1] is provided between two adjacent nozzles N. That is, in the Y-axis direction, the dot Dty formed by the nozzle NQ1[1]{j} and the nozzle NQ1[1]{j + 1} has the dot Dty formed by the nozzle NQ2[1]{j} positioned therebetween. Thereby, the head module 2QS can improve the resolution in the Y-axis direction. In the second embodiment, the nozzle NQ is an example of the "nozzle".

[0147] The head module 2QS according to the second embodiment further includes a head chip 3Q[1] having a nozzle row LQ1[1] and a nozzle row LQ2[1], and a head chip 3Q[2] having a nozzle row LQ1[2]. That is, two nozzle rows that form dots Dty at the same position in the X-axis direction are provided on one head chip 3Q. Thereby, the deviation of the landing position of the dot Dty in the X-axis direction is less likely to occur, and the printing accuracy is improved. In the second embodiment, the head chip 3Q[1] is an example of the "first head chip", and the head chip 3Q[2] is an example of the "second head chip".

[0148] In the head module 2QS according to the second embodiment, the head chip 3Q[1] having the nozzle row LQ1[1] and the nozzle row LQ2[1] and the head chip 3Q[2] having the nozzle row LQ1[2] have a common structure. Thereby, the manufacturing cost of the head chip can be reduced.

[0149] Further, in the head module 2QS according to the second embodiment, the head chip 3Q[1] including the nozzle rows LQ1[1] and LQ2[1] includes a nozzle plate CQ[1] provided with the nozzle rows LQ1[1] and LQ2[1], and the head chip 3Q[2] including the nozzle row LQ1[2] includes a nozzle plate CQ[2] provided with the nozzle row LQ1[2]. This makes it possible to improve the alignment accuracy of two nozzle rows capable of forming dots Dty at the same position in the X-axis direction. In the second embodiment, the nozzle plate CQ[1] is an example of the "first nozzle plate", and the nozzle plate CQ[2] is an example of the "second nozzle plate".

[0150] Also, in the head module 2QS according to the second embodiment, a head chip 3Q[1] including a nozzle row LQ1[1] and a nozzle row LQ2[1] and a head chip 3Q[2] including a nozzle row LQ1[2] are fixed, and a fixing plate 26 having a plate opening W for exposing at least the nozzle row LQ1[1] and the nozzle row LQ2[1] among the nozzle plates CQ[1] and at least the nozzle row LQ1[2] among the nozzle plates CQ[2] is provided. The head chip 3Q[1] including the nozzle row LQ1[1] and the nozzle row LQ2[1] and the head chip 3Q[2] including the nozzle row LQ1[2] are fixed to the fixing plate 26 such that the distance in the X-axis direction between the center of the head chip 3Q[1] including the nozzle row LQ1[1] and the nozzle row LQ2[1] and the center of the head chip 3Q[2] including the nozzle row LQ1[2] becomes the nozzle row interval DQ1[1][2] when the fixing plate 26 is viewed in plan. In the X-axis direction, the center of each head chip coincides with the center of the nozzle plate C provided in each head chip. Also, in the X-axis direction, the distance between the center of the nozzle plate CQ[m] and the center of the plate opening WQ[m] is constant. That is, the head chip 3Q[1] including the nozzle row LQ1[1] and the nozzle row LQ2[1] and the head chip 3Q[2] including the nozzle row LQ1[2] are fixed to the fixing plate 26 such that the distance between their centers in the X-axis direction coincides with the plate opening interval UQ[1][2] and also coincides with the nozzle row interval DQ1[1][2]. Also, a plurality of head chips 3Q are provided in the head module 2QS at regular intervals. Thereby, when printing is performed using the head module 2QS according to the second embodiment, compared with the case where the same printing is performed using a plurality of head modules such that the total number of nozzles N and nozzles of the head module 2QS in the X-axis direction is equal, the scattering of the landing positions of the dots Dt is less likely to occur, and the printing accuracy is improved. Note that in the second embodiment, the plate opening W is an example of an "opening", and the fixing plate 26 is an example of a "fixing plate".

[0151] Further, the head module 2QS according to the second embodiment has a supply channel 251 for supplying ink to a head chip 3Q[1] including nozzle rows LQ1[1] and LQ2[1] and a head chip 3Q[2] including a nozzle row LQ1[2], and the X-axis direction-related interval between the center of the head chip 3Q[1] including the nozzle rows LQ1[1] and LQ2[1] and the center of the head chip 3Q[2] including the nozzle row LQ1[2] is the nozzle row interval DQ1[1][2]. The head module 2QS is characterized by including a holder 25 that holds the head chip 3Q[1] including the nozzle rows LQ1[1] and LQ2[1] and the head chip 3Q[2] including the nozzle row LQ1[2]. Thereby, ink can be supplied to each head chip. Note that in the second embodiment, the supply channel 251 is an example of a "supply channel", and the holder 25 is an example of a "holder".

[0152] Further, the head module 2QS according to the second embodiment includes an inlet 220 for introducing a liquid, and a distribution channel 221 that communicates with nozzles NQ1[1]{j} and NQ1[2]{j} and distributes the ink introduced from the inlet 220 to the nozzles NQ1[1]{j} and NQ1[2]{j}. The head module 2QS is characterized by this. Thereby, the same ink can be supplied to a plurality of nozzles N. Note that in the second embodiment, the inlet 220 is an example of an "inlet", and the distribution channel 221 is an example of a "distribution channel".

[0153] Further, the inkjet printer according to the second embodiment includes the head module 2QS according to the second embodiment and a carriage 761 that reciprocates the head module 2QS in the X-axis direction and the opposite direction of the X-axis direction. The inkjet printer is characterized by this. By performing a printing operation using the inkjet printer including the head module 2QS according to the second embodiment, the occurrence of dot Dty overlap and gaps can be suppressed, and high-speed and high-resolution printing can be performed. Note that in the second embodiment, the inkjet printer is an example of a "liquid ejection device", and the carriage 761 is an example of a "carriage".

[0154] Also, in the inkjet printer according to the second embodiment, the minimum interval in the X-axis direction between two dots Dty formed by the nozzle NQ1[1]{j} is the interval obtained by dividing the nozzle row interval DL by the value E1 and is also twice the basic resolution unit ΔX which is the interval obtained by dividing the nozzle row interval DQ1[1][2] by the value O1. That is, the head module 2QS mounted on the inkjet printer according to the second embodiment is scanned in the X-axis direction at a speed that advances by twice the basic resolution unit ΔX, that is, the interval G, while forming two dots Dty from a specific nozzle NQ. Further, in the X-axis direction, the nozzle row interval DL is set to an integral multiple of the interval G with respect to the minimum interval G between the dots Dty formed by a specific nozzle NQ provided in the head module 2QS. Thereby, when forming the dots Dty from the nozzle NQ1[1]{j} provided in the nozzle row LQ1[1] and the nozzle NQ2[1]{j} provided in the nozzle row LQ2[1] while the head module 2QS is scanned in the X-axis direction, the dot Dty formed from the nozzle NQ1[1]{j} and the dot Dty formed from the nozzle NQ2[1]{j} can be formed at the same position in the X-axis direction. Note that in the second embodiment, the dot Dty is an example of a "dot", and the basic resolution unit ΔX is an example of an "interval P0".

[0155] Also, in the inkjet printer according to the second embodiment, the nozzles NQ1[1]{j}, NQ2[1]{j}, and NQ1[2]{j} can eject ink at the same timing. Thereby, it becomes possible to form the dots Dty at a predetermined interval.

[0156] In the inkjet printer according to the second embodiment, a common drive signal Com is supplied to a first drive element corresponding to nozzle NQ1[1]{j}, a second drive element corresponding to nozzle NQ2[1]{j}, and a third drive element corresponding to nozzle NQ1[2]{j}. This makes it possible to reduce the size and cost of the apparatus. In the second embodiment, as an example, the "first drive element" is the piezoelectric element 331 corresponding to nozzle NQ1[1]{j} provided on nozzle plate CQ[1], the "second drive element" is the piezoelectric element 332 corresponding to nozzle NQ2[1]{j} provided on nozzle plate CQ[1], and the "third drive element" is the piezoelectric element 331 corresponding to nozzle NQ1[2]{j} provided on nozzle plate CQ[2]. Also, drive signal Com is an example of a "drive signal".

[0157] In the inkjet printer according to the second embodiment, nozzles NQ1[1]{j}, NQ2[1]{j}, and NQ1[2]{j} eject the same type of ink. That is, the same type of ink is ejected from nozzle NQ2[1]{j} and nozzles NQ1[1]{j} and NQ1[2]{j} which are provided at different positions in the Y-axis direction. This makes it possible to achieve higher resolution in the Y-axis direction.

[0158] In the inkjet printer according to the second embodiment, nozzles NQ1[1]{j}, NQ2[1]{j}, and NQ1[2]{j} eject the same type of ink. In the Y-axis direction orthogonal to the X-axis direction, among the plurality of nozzles NQ included in nozzle row LQ1[1], the interval between two adjacent nozzles NQ is twice the basic resolution unit ΔX. In the Y-axis direction orthogonal to the X-axis direction, the interval between nozzle NQ1[1]{j} and nozzle NQ2[1]{j} is the basic resolution unit ΔX. This makes it possible to align the resolutions in both the main scanning direction and the sub-scanning direction.

[0159] 3. Third Embodiment Hereinafter, the third embodiment of the present invention will be described.

[0160] The inkjet printer according to the third embodiment is different from the inkjet printers according to the first and second embodiments described above in that, for each head chip 3, the positions of the nozzles N1[m]{j} constituting the nozzle row L1 provided in the head chip 3 in the Y-axis direction and the positions of the nozzles N2[m]{j} constituting the nozzle row L2 provided in the head chip 3 in the Y-axis direction are the same.

[0161] Specifically, the inkjet printer according to the third embodiment is different from the inkjet printer 1 according to the first embodiment in that it includes a head module 2A instead of the head module 2. The head module 2A includes M head chips 3A. The head chip 3A is different from the head chip 3 according to the first embodiment in that it includes a nozzle plate CA instead of the nozzle plate C. That is, in the present embodiment, the head module 2A includes M nozzle plates CA[1] to CA[M]. Hereinafter, among the M nozzle plates CA[1] to CA[M] provided in the head module 2A, the m-th nozzle plate CA from the -X direction is referred to as the nozzle plate CA[m]. Also, based on the change from the nozzle plate C to the nozzle plate CA, the pressure chamber forming substrate 34, the flow path substrate 35, the wiring substrate 30, etc. of the head chip 3A are different from those of the head chip 3.

[0162] FIG. 13 is an explanatory diagram showing the positional relationship between the M nozzle plates CA included in the head module 2A and the fixing plate 26. Note that FIG. 13 shows various positional relationships when the head module 2A is viewed in perspective from the -Z direction to the +Z direction. Also, hereinafter, the case where M = 4 will be exemplified and described.

[0163] As shown in FIG. 13, in the present embodiment, M nozzle plates CA[1] to CA[M] are fixed to the fixed plate 26. In the present embodiment, it is assumed that the M nozzle plates CA[1] to CA[M] all have the same structure. Further, the nozzle plate CA[m2] is located in the +X direction of the nozzle plate CA[m1]. Here, as described above, the values m1 and m2 are natural numbers satisfying 1 ≦ m1 < m2 ≦ M.

[0164] As shown in FIG. 13, a nozzle row L1[m] and a nozzle row L2[m] are provided on the nozzle plate CA[m]. As described above, the interval in the X-axis direction between the nozzle row L1[m] and the nozzle row L2[m] is set to the nozzle row interval DL. Further, as described above, the interval in the X-axis direction between the nozzle row L1[m1] and the nozzle row L1[m2] is referred to as the nozzle row interval D1[m1][m2], and the interval in the X-axis direction between the nozzle row L2[m1] and the nozzle row L2[m2] is referred to as the nozzle row interval D2[m1][m2]. Further, as described above, among the J nozzles N provided in the nozzle row L1[m], the j-th nozzle N from the -Y direction side is referred to as the nozzle N1[m]{j}, and among the J nozzles N provided in the nozzle row L2[m], the j-th nozzle N from the -Y direction side is referred to as the nozzle N2[m]{j}.

[0165] As shown in FIG. 13, in the present embodiment, on the nozzle plate CA[m], the nozzles N1[m]{1} to N1[m]{J} and the nozzles N2[m]{1} to N2[m]{J} are provided such that the positions in the Y-axis direction of the nozzles N1[m]{j} and the nozzles N2[m]{j} are the same. Further, in the present embodiment, the interval in the Y-axis direction between the nozzle N1[m]{j} and the nozzle N1[m]{j + 1}, and the interval in the Y-axis direction between the nozzle N2[m]{j} and the nozzle N2[m]{j + 1} are both the basic resolution unit ΔY.

[0166] The fixed plate 26 is provided with M plate openings W[1] to W[M] that correspond one-to-one with M nozzle plates CA[1] to CA[M]. The nozzle plate CA[m] is fixed such that the nozzle row L1[m] and the nozzle row L2[m] are exposed from the plate opening W[m] provided in the fixed plate 26. As described above, the distance in the X-axis direction between the center of the plate opening W[m1] and the center of the plate opening W[m2] is referred to as the plate opening interval U[m1][m2]. Assume a case where the plate opening interval U[m1][m2] becomes a constant interval when the value m1 and the value m2 satisfy "m2 = 1 + m1". Also assume a case where the distance in the X-axis direction between the center of the nozzle plate C[m] and the center of the plate opening W[m] is constant.

[0167] Figs. 14 to 16 are explanatory diagrams illustrating the positional relationship between the operation of the head module 2A when performing a printing operation using the head module 2A shown in Fig. 13 and the dots Dt formed by the head module 2A.

[0168] In Figs. 14 to 16, among the total 2×M×J nozzles N provided in the head module 2A shown in Fig. 13, M nozzles N1[1]{j} to N1[M]{j}, M nozzles N2[1]{j} to N2[M]{j}, M nozzles N1[1]{j + 1} to N1[M]{j + 1}, and M nozzles N2[1]{j + 1} to N2[M]{j + 1} are focused on to explain the printing operation. As described above, in this embodiment, a case where M = 4 is assumed. Therefore, in Figs. 14 to 16, four nozzles N1[1]{j} to N1[4]{j}, four nozzles N2[1]{j} to N2[4]{j}, four nozzles N1[1]{j + 1} to N1[4]{j + 1}, and four nozzles N2[1]{j + 1} to N2[4]{j + 1} are shown.

[0169] In FIGS. 14 to 16, the head module 2A discharges ink while moving in the +X direction over time to form dots Dt. Among these, FIG. 14 illustrates the positional relationship between the head module 2A and the dots Dt when the time T is from Tc + 1t to Tc + 4t. Further, FIG. 15 illustrates the positional relationship between the head module 2A and the dots Dt when the time T is from Tc + 5t to Tc + 8t. Further, FIG. 16 illustrates the positional relationship between the head module 2A and the dots Dt when the time T is from Tc + 9t to Tc + 12t. In FIGS. 14 to 16, among the plurality of dots Dt formed by the plurality of nozzles N provided in the head module 2A, the dot Dt formed by the ink discharged from the nozzle N2 is referred to as the dot Dtd.

[0170] In the present embodiment, each of the plurality of nozzles N provided in the head module 2A discharges the first ink at the time T = Tc + 1t to form a dot Dt on the recording paper PE, and thereafter, a new dot Dt is formed every time the time t elapses. Further, the head module 2A is scanned at a speed that advances by an interval G every time the time t elapses after the time T = Tc + 1t. In the present embodiment, it is assumed that the interval G is M times the basic resolution unit ΔX. Specifically, in the present embodiment, as described above, M = 4. Therefore, in the present embodiment, the scanning speed of the head module 2A is set so that the interval G becomes G = 4ΔX. Further, in the present embodiment, it is assumed that the basic resolution unit ΔX is 1 / 2 times the basic resolution unit ΔY.

[0171] In the present embodiment, the nozzle row interval DL is set to a natural number multiple of the interval G. Specifically, the nozzle row interval DL is set to α times the interval G. That is, the nozzle row interval DL is set to (M × α) times the basic resolution unit ΔX. In other words, DL = (M × α)ΔX. That is, in the present embodiment, DL = 4 × α × ΔX. Here, the value α is a natural number of 1 or more. Also, in the present embodiment, the nozzle row interval D1[1][ma] is set to an interval different from an integral multiple of the interval G. Specifically, the nozzle row interval D1[1][ma] is set to an interval obtained by adding β[ma] times the interval G and γ[ma] times the basic resolution unit ΔX. That is, the nozzle row interval D1[1][ma] is set to (M×β[ma]+γ[ma]) times the basic resolution unit ΔX. In other words, D1[1][ma]=(M×β[ma]+γ[ma])ΔX. As described above, the value ma is a natural number satisfying 2≦ma≦M. Also, the value β[ma] is a natural number satisfying α<β[ma]. Also, the value γ[ma] is a natural number satisfying 1≦γ[ma]≦M−1 and γ[ma1]≠γ[ma2]. Also, the values ma1 and ma2 are natural numbers satisfying 2≦ma1<ma2≦M. As described above, in the present embodiment, in the X-axis direction, the nozzle row interval DL and the nozzle row interval D1[1][ma] are set so as to satisfy DL:D1[1][ma]=Mα:Mβ[ma]+γ[ma].

[0172] In FIGS. 14 to 16, the position of the nozzle N1[1]{j} in the X-axis direction at the time T = Tc + 1t is AX = 0. Therefore, the nozzle N1[1]{j} can form a dot Dt for AX = 4k - 4 at the time T = Tc + kt. In other words, the nozzle N1[1]{j} can form a dot Dt for AX = 4×k1. Here, the variable k is a natural number of 1 or more. Also, in the present embodiment, the variable k1 is an integer satisfying k1 = k−1. Note that in FIGS. 14 to 16, the case where α = 1 is assumed. Therefore, the nozzle N2[1]{j} can form a dot Dtd for AX = 4k at the time T = Tc + kt. In other words, the nozzle N2[1]{j} can form a dot Dtd for AX = 4×(k1 + 1).

[0173] Also, in FIGS. 14 to 16, the position of the nozzle N1[2]{j} in the X-axis direction at time T = Tc + 1t is AX = 9. That is, in FIGS. 14 to 16, D1[1][2]=(4×β[2]+γ[2]) = 9. That is, in FIGS. 14 to 16, when ma = 2, β[2]=2 and γ[2]=1. And the nozzle N1[2]{j} can form a dot Dt at AX = 4k + 5 at time T = Tc + kt. In other words, the nozzle N1[2]{j} can form a dot Dt at AX = 4×k2 + 1. Here, in the present embodiment, the variable k2 is an integer that satisfies k2 = k + 1. Also, in FIGS. 14 to 16, the nozzle N2[2]{j} can form a dot Dtd at AX = 4k + 9 at time T = Tc + kt. In other words, the nozzle N2[2]{j} can form a dot Dtd at AX = 4×(k2 + 1)+1.

[0174] Also, in FIGS. 14 to 16, the position of the nozzle N1[3]{j} in the X-axis direction at time T = Tc + 1t is AX = 18. That is, in FIGS. 14 to 16, D1[1][3]=(4×β[3]+γ[3]) = 18. That is, in FIGS. 14 to 16, when ma = 3, β[3]=4 and γ[3]=2. And the nozzle N1[3]{j} can form a dot Dt at AX = 4k + 14 at time T = Tc + kt. In other words, the nozzle N1[3]{j} can form a dot Dt at AX = 4×k3 + 2. Here, in the present embodiment, the variable k3 is an integer that satisfies k3 = k + 3. Also, in FIGS. 14 to 16, the nozzle N2[3]{j} can form a dot Dtd at AX = 4k + 18 at time T = Tc + kt. In other words, the nozzle N2[3]{j} can form a dot Dtd at AX = 4×(k3 + 1)+2.

[0175] Also, in FIGS. 14 to 16, the position of the nozzle N1[4]{j} in the X-axis direction at time T = Tc + 1t is AX = 27. That is, in FIGS. 14 to 16, D1[1][4]=(4×β[4]+γ[4]) = 27. That is, in FIGS. 14 to 16, when ma = 4, β[4]=6 and γ[4]=3. And the nozzle N1[4]{j} can form a dot Dt at AX = 4k + 23 at time T = Tc + kt. In other words, the nozzle N1[4]{j} can form a dot Dt at AX = 4×k4 + 3. Here, in this embodiment, the variable k4 is an integer that satisfies k4 = k + 5. Also, in FIGS. 14 to 16, the nozzle N2[4]{j} can form a dot Dtd at AX = 4k + 27 at time T = Tc + kt. In other words, the nozzle N2[4]{j} can form a dot Dtd at AX = 4×(k4 + 1)+3.

[0176] As described above, according to this embodiment, the nozzle N1[1]{j} can form a dot Dt at AX = M×k1, and the nozzle N1[ma]{j} can form a dot Dt at AX = M×ka + γ[ma]. Note that, as described above, the variable ka is an integer that satisfies ka = k + β[ma] - 1. Therefore, according to this embodiment, it is possible to form a plurality of dots Dt at intervals of the basic resolution unit ΔX without overlapping in the X-axis direction by the M nozzles N1[1]{j} to N1[M]{j}. Specifically, in FIGS. 14 to 16, it is possible to form a plurality of dots Dt at intervals of the basic resolution unit ΔX without overlapping in the X-axis direction by the four nozzles N1[1]{j} to N1[4]{j}.

[0177] Furthermore, according to this embodiment, the nozzle N2[1]{j} can form a dot Dtd for AX = M×(k1 + 1), and the nozzle N2[ma]{j} can form a dot Dtd for AX = M×(ka + 1) + γ[ma]. Therefore, according to this embodiment, by the M nozzles N2[1]{j} to N2[M]{j}, in the X-axis direction, a plurality of dots Dtd can be formed at intervals of the basic resolution unit ΔX without overlapping. Specifically, in FIGS. 14 to 16, by the four nozzles N2[1]{j} to N2[4]{j}, in the X-axis direction, a plurality of dots Dtd can be formed at intervals of the basic resolution unit ΔX without overlapping.

[0178] Also, according to this embodiment, the nozzle N2[m]{j} can form a dot Dtd at the same position where the nozzle N1[m]{j} forms a dot Dt. Therefore, if a discharge abnormality such as ink not being discharged occurs in the nozzle N1[m]{j} and the dot Dt cannot be formed on the recording paper PE by the ink discharged from the nozzle N1[m]{j}, the dot Dtd formed by the ink discharged from the nozzle N2[m]{j} can replace the dot Dt that was supposed to be formed by the ink discharged from the nozzle N1[m]{j}. For this reason, according to this embodiment, even when a discharge abnormality occurs in some of the plurality of nozzles N provided in the head module 2A, it is possible to suppress the degree of deterioration of the image quality formed by the head module 2A.

[0179] In the present embodiment, the control unit 8 inspects whether or not ejection abnormalities have occurred in each of the plurality of nozzles N provided in the head module 2A. Specifically, in the present embodiment, the control unit 8 first drives the piezoelectric element 331 or the piezoelectric element 332 corresponding to the nozzle N with the drive signal Com to generate vibration in the piezoelectric element 331 or the piezoelectric element 332. Next, the control unit 8 inspects whether or not ejection abnormalities have occurred in the nozzle N based on the waveform of the vibration generated in the piezoelectric element 331 or the piezoelectric element 332. And when the control unit 8 obtains the inspection result that ejection abnormalities have occurred in the nozzle N1[m]{j}, by changing the print signal SI, instead of ejecting ink from the nozzle N1[m]{j}, ink is ejected from the nozzle N2[m]{j}. Further, when the control unit 8 obtains the inspection result that ejection abnormalities have occurred in the nozzle N2[m]{j}, by changing the print signal SI, instead of ejecting ink from the nozzle N2[m]{j}, ink is ejected from the nozzle N1[m]{j}.

[0180] 4. Fourth Embodiment Hereinafter, the fourth embodiment of the present invention will be described.

[0181] The inkjet printer according to the fourth embodiment is different from the inkjet printer 1 according to the first embodiment in that the positions of the nozzle plates C[1] and C[3] in the Y-axis direction and the positions of the nozzle plates C[2] and C[4] in the Y-axis direction are different.

[0182] Specifically, the inkjet printer according to the fourth embodiment is different from the inkjet printer 1 according to the first embodiment in that it includes a head module 2B instead of the head module 2. The head module 2B includes M head chips 3. As described above, the head chip 3 includes a nozzle plate C.

[0183] FIG. 17 is an explanatory diagram showing the positional relationship between the M nozzle plates C provided in the head module 2B and the fixed plate 26. Note that FIG. 17 shows various positional relationships when the head module 2B is viewed in perspective from the -Z direction to the +Z direction. In the following, the case where M = 4 will be illustrated and described.

[0184] As shown in FIG. 17, in the present embodiment, M nozzle plates C[1] to C[M] are fixed to the fixed plate 26. In the present embodiment, it is assumed that the M nozzle plates C[1] to C[M] all have the same structure. Also, the nozzle plate C[m2] is located in the +X direction of the nozzle plate C[m1]. Here, as described above, the values m1 and m2 are natural numbers that satisfy 1 ≦ m1 < m2 ≦ M.

[0185] As described above, the nozzle plate C[m] is provided with a nozzle row L1[m] and a nozzle row L2[m]. Also, as described above, among the J nozzles N provided in the nozzle row L1[m], the j-th nozzle N from the -Y direction side is referred to as the nozzle N1[m]{j}, and among the J nozzles N provided in the nozzle row L2[m], the j-th nozzle N from the -Y direction side is referred to as the nozzle N2[m]{j}. As shown in FIG. 17, the nozzle N1[m]{j} is provided on the -Y direction side of the nozzle N2[m]{j}. In the present embodiment, the interval in the Y-axis direction between the nozzle N1[m]{j} and the nozzle N2[m]{j} is the interval R, and the interval in the Y-axis direction between the nozzle N2[m]{j} and the nozzle N1[m]{j + 1} is also the interval R.

[0186] Also, in the present embodiment, the nozzle N1[mz1]{j} is located in the -Y direction relative to the nozzle N1[mz2]{j}, and the nozzle N2[mz1]{j} is located in the -Y direction relative to the nozzle N2[mz2]{j}. Here, the value mz1 is an odd number satisfying 1 ≦ mz1 ≦ M, and the value mz2 is an even number satisfying 2 ≦ mz2 ≦ M. However, the present invention is not limited to such a mode. For example, the nozzle N1[mz1]{j} may be located in the +Y direction relative to the nozzle N1[mz2]{j}, and the nozzle N2[mz1]{j} may be located in the +Y direction relative to the nozzle N2[mz2]{j}. Also, in the present embodiment, the interval in the Y-axis direction between the nozzle N1[mz1]{j} and the nozzle N1[mz2]{j} is 1 / 2 of the interval R, and the interval in the Y-axis direction between the nozzle N2[mz1]{j} and the nozzle N2[mz2]{j} is 1 / 2 of the interval R. That is, in the present embodiment, the nozzle plates C[1] to C[M] are arranged such that the nozzle plate C[mz1] is displaced by 1 / 2 of the interval R in the -Y direction relative to the nozzle plate C[mz2]. Hereinafter, the interval of 1 / 2 of the interval R will be referred to as the interval Rh. In the present embodiment, the nozzle plate CA[m] is fixed such that the nozzle rows L1[m] and the nozzle rows L2[m] are exposed from the plate opening W[m] provided in the fixed plate 26.

[0187] In the present embodiment as well, the interval in the X-axis direction between the nozzle rows L1[m1] and the nozzle rows L1[m2] is referred to as the nozzle row interval D1[m1][m2], and the interval in the X-axis direction between the nozzle rows L2[m1] and the nozzle rows L2[m2] is referred to as the nozzle row interval D2[m1][m2]. Also, in the present embodiment as well, the interval in the X-axis direction between the center of the plate opening W[m1] and the center of the plate opening W[m2] is referred to as the plate opening interval U[m1][m2].

[0188] Figs. 18 to 20 are explanatory diagrams illustrating the positional relationship between the operation of the head module 2B when performing a printing operation using the head module 2B shown in Fig. 17 and the dots Dt formed by the head module 2B. In Figs. 18 to 20, among the total of 2×M×J nozzles N provided in the head module 2B shown in Fig. 17, M nozzles N1[1]{j} to N1[M]{j}, M nozzles N2[1]{j} to N2[M]{j}, M nozzles N1[1]{j + 1} to N1[M]{j + 1}, and M nozzles N2[1]{j + 1} to N2[M]{j + 1} are focused on to explain the printing operation. As described above, in this embodiment, the case where M = 4 is assumed. Therefore, in Figs. 18 to 20, 4 nozzles N1[1]{j} to N1[4]{j}, 4 nozzles N2[1]{j} to N2[4]{j}, 4 nozzles N1[1]{j + 1} to N1[4]{j + 1}, and 4 nozzles N2[1]{j + 1} to N2[4]{j + 1} are shown.

[0189] Also, Figs. 18 to 20 illustrate the formation process of the dots Dt when the head module 2B discharges ink while moving in the +X direction over time. Among these, Fig. 18 illustrates the positional relationship between the head module 2B and the dots Dt when the time T is from Tc + 1t to Tc + 3t. Fig. 19 illustrates the positional relationship between the head module 2B and the dots Dt when the time T is from Tc + 4t to Tc + 6t. Fig. 20 illustrates the positional relationship between the head module 2B and the dots Dt when the time T is from Tc + 7t to Tc + 9t. In Figs. 18 to 20, for clarity, the position of the nozzle plate C[m] in the X-axis direction at each time is illustrated below the rectangular dashed line representing the head module 2B using a rectangular dashed line having a height of the interval Rh. Also, for the convenience of illustration, in Figs. 18 to 20, the dots Dt are represented as squares with an interval of Rh in both the X-axis direction and the Y-axis direction.

[0190] In this embodiment, each of the plurality of nozzles N provided in the head module 2B ejects the first ink at time T = Tc + 1t to form a dot Dt on the recording paper PE, and thereafter, a new dot Dt is formed every time the time t elapses. Further, after time T = Tc + 1t, the head module 2B is scanned at a speed that advances by an interval G every time the time t elapses. In this embodiment, the interval G is defined as a value obtained by multiplying the number Mh of head chips 3 having the same position in the Y-axis direction with respect to the interval R and the reciprocal Mg of the value obtained by dividing the value M by the value Mh. In the examples of FIGS. 18 to 20, Mh = 2. Also, the value Mg is 1 / 2. Therefore, in the examples of FIGS. 18 to 20, the interval G is equal to the interval R. In other words, in the examples of FIGS. 18 to 20, the interval G is twice the interval Rh. That is, in this embodiment, the scanning speed of the head module 2B is set such that the interval G is G = R = 2Rh. In FIGS. 18 to 20, for convenience of explanation, as the X-axis coordinate AX, the position of the nozzle N1[1]{j} at time T = Tc + 1t is set to "0", and a value that increases by "1" every time it moves by an interval Rh in the +X direction is given. For example, in FIGS. 18 to 20, while the time T elapses from Tc + 1t to Tc + 2t, the position of the nozzle N2[4]{j} provided in the head module 2B moves from AX = 15 to AX = 17.

[0191] In this embodiment, the nozzle row interval DL is set to a natural number multiple of the interval G. Specifically, the nozzle row interval DL is set to α times the interval G. That is, the nozzle row interval DL is DL = αG = αR = 2αRh. Here, the value α is a natural number of 1 or more. Assuming the case where the value α is 1 in FIGS. 18 to 20. Therefore, in FIGS. 18 to 20, the nozzle row interval DL is DL = 2Rh. Also, in FIGS. 18 to 20, the nozzle row interval D1[mz1][mz1 + 1] is set to a natural number multiple of the interval G. For example, in FIGS. 18 to 20, the nozzle row intervals D1[1][2] and D1[3][4] are set to twice the interval G, that is, 4Rh. Also, in FIGS. 18 to 20, The nozzle row interval D1[1][3] is set to an interval different from an integral multiple of the interval G. For example, in FIGS. 18 to 20, the nozzle row interval D1[1][3] is set to 9Rh.

[0192] In FIGS. 18 to 20, the position of the nozzle N1[1]{j} in the X-axis direction at time T = Tc + 1t becomes AX = 0. Therefore, the nozzle N1[1]{j} can form dots Dt for AX = 0, 2, 4, 6,..., 2×k1,.... Here, the variable k1 is an integer of 0 or more. In FIGS. 18 to 20, the position of the nozzle N2[1]{j} in the X-axis direction at time T = Tc + 1t becomes AX = 2. Therefore, the nozzle N2[1]{j} can form dots Dt for AX = 2, 4, 6, 8,..., 2×k2,.... Here, the variable k2 is an integer of 1 or more. In FIGS. 18 to 20, the position of the nozzle N1[2]{j} in the X-axis direction at time T = Tc + 1t becomes AX = 4. Therefore, the nozzle N1[2]{j} can form dots Dt for AX = 4, 6, 8, 10,..., 2×k3,.... Here, the variable k3 is an integer of 2 or more. In FIGS. 18 to 20, the position of the nozzle N2[2]{j} in the X-axis direction at time T = Tc + 1t becomes AX = 6. Therefore, the nozzle N2[2]{j} can form dots Dt for AX = 6, 8, 10, 12,..., 2×k4,.... Here, the variable k4 is an integer of 3 or more.

[0193] In FIGS. 18 to 20, the position of the nozzle N1[3]{j} in the X-axis direction at time T = Tc + 1t becomes AX = 9. Therefore, the nozzle N1[3]{j} can form dots Dt for AX = 9, 11, 13, 15,..., 2×k5 + 1,.... Here, the variable k5 is an integer of 4 or more. In FIGS. 18 to 20, the position of the nozzle N2[3]{j} in the X-axis direction at time T = Tc + 1t is AX = 11. Therefore, the nozzle N2[3]{j} can form dots Dt for AX = 11, 13, 15, 17, …, 2×k6 + 1, …. Here, the variable k6 is an integer of 5 or more. In FIGS. 18 to 20, the position of the nozzle N1[4]{j} in the X-axis direction at time T = Tc + 1t is AX = 13. Therefore, the nozzle N1[4]{j} can form dots Dt for AX = 13, 15, 17, 19, …, 2×k7 + 1, …. Here, the variable k7 is an integer of 6 or more. In FIGS. 18 to 20, the position of the nozzle N2[4]{j} in the X-axis direction at time T = Tc + 1t is AX = 15. Therefore, the nozzle N2[4]{j} can form dots Dt for AX = 15, 17, 19, 21, …, 2×k8 + 1, …. Here, the variable k8 is an integer of 7 or more.

[0194] As described above, in FIGS. 18 to 20, dots Dt are formed at positions where the X-axis coordinate AX is an even multiple of the interval Rh by the nozzles N1[1]{j}, N2[1]{j}, N1[2]{j}, and N2[2]{j}, and dots Dt are formed at positions where the X-axis coordinate AX is an odd multiple of the interval Rh by the nozzles N1[3]{j}, N2[3]{j}, N1[4]{j}, and N2[4]{j}. Therefore, according to the present embodiment, a plurality of dots Dt can be formed such that the intervals in the X-axis direction and the Y-axis direction are both Rh by the plurality of nozzles N provided in the head module 2B.

[0195] 5. Modification Each of the above embodiments can be variously modified. Specific modification modes are exemplified below. Also, two or more modes arbitrarily selected from the following examples can be appropriately combined within a range where they do not conflict with each other. In the modification examples exemplified below, for elements whose actions and functions are equivalent to those of the above-described embodiments, the reference numerals used in the above description are reused, and the detailed description of each is appropriately omitted.

[0196] 5.1. Variant Example 1 In the above-described first embodiment, the case where the nozzles N1[m]{j} and the nozzles N2[m]{j} eject ink of the same color has been exemplified and described. However, the present invention is not limited to such a mode. For example, the nozzles N1[m]{j} and the nozzles N2[m]{j} may eject ink of different colors.

[0197] The inkjet printer according to this variant example includes a head module having a plurality of head chips, like the head module 2 shown in FIG. 5. And the head chips included in the inkjet printer according to this variant example include a nozzle plate C[m] provided with a nozzle row L1[m] and a nozzle row L2[m], as shown in FIG. 5. In the inkjet printer according to this variant example, the ink ejected from the nozzles N1[m]{j} belonging to the nozzle row L1[m] and the ink ejected from the nozzles N2[m]{j} belonging to the nozzle row L2[m] have different colors. Specifically, in this variant example, yellow ink is ejected from the nozzles N1[m]{j} belonging to the nozzle row L1[m], and cyan ink is ejected from the nozzles N2[m]{j} belonging to the nozzle row L2[m].

[0198] Also, in this modified example, similar to the first embodiment described above, the scanning speed of the head module is set such that the interval G is G = M × ΔX. Therefore, the inkjet printer according to this modified example can form a plurality of dots Dty in the X-axis direction without overlapping, with the basic resolution unit ΔX, by the M nozzles N1[1]{j} to N1[M]{j}. Similarly, a plurality of dots Dtc can be formed in the X-axis direction without overlapping, with the basic resolution unit ΔX, by the M nozzles N2[1]{j} to N2[M]{j}. Further, the inkjet printer according to this modified example can form a plurality of dots Dty in the Y-axis direction with the basic resolution unit ΔY, and can form a plurality of dots Dtc in the Y-axis direction with the basic resolution unit ΔY. Here, the basic resolution unit ΔY of this modified example corresponds to twice the basic resolution unit ΔX.

[0199] In this modified example, the scanning speed of the head module may also be a value obtained by multiplying the number of nozzle rows provided in the nozzle plate C[m]. That is, the scanning speed of the head module may be set to 2×G. In other words, the interval G may be a value obtained by multiplying the number of nozzle rows provided in the nozzle plate C[m], the value M, and the interval R. Specifically, the scanning speed of the head module may be set such that the interval G satisfies G = 2M×R. In this case, similar to the interval G, the nozzle row interval DL is doubled. That is, the nozzle row interval DL = 2×α×M×R. Also, in this case, similar to the interval G, the nozzle row interval D1[1][ma] is doubled. That is, the nozzle row interval D1[1][ma] = 2×(M×β[ma] + γ[ma])×R. In this case, the basic resolution unit ΔX is twice the interval R, and the basic resolution unit ΔY is twice the interval R. That is, the interval G is G = M×ΔX, the nozzle row interval DL is DL = α×M×ΔX, and the nozzle row interval D1[1][ma] is D1[1][ma] = (M×β[ma] + γ[ma])×ΔX. In this case, the inkjet printer according to this modified example can form a plurality of dots Dty in the X-axis direction without overlapping at intervals of the basic resolution unit ΔX, that is, intervals twice the interval R, by M nozzles N1[1]{j} to N1[M]{j}. Similarly, a plurality of dots Dtc can be formed in the X-axis direction without overlapping at intervals of the basic resolution unit ΔX by M nozzles N2[1]{j} to N2[M]{j}. Also, in this case, the inkjet printer according to this modified example can form a plurality of dots Dty in the Y-axis direction at intervals of the basic resolution unit ΔY, that is, intervals twice the interval R. Similarly, the inkjet printer according to this modified example can form a plurality of dots Dtc in the Y-axis direction at intervals of the basic resolution unit ΔY.

[0200] 5.2. Modified Example 2 In the above-described second embodiment, as shown in FIG. 9, a case where yellow ink is ejected from the nozzle NQ provided on the nozzle plate CQ and cyan ink is ejected from the nozzle NS provided on the nozzle plate CS was exemplified. However, the present invention is not limited to such an aspect. For example, in this modification, in FIG. 9, the nozzle NQ1 belonging to the nozzle row LQ1 provided on the nozzle plate CQ and the nozzle NS2 belonging to the nozzle row LS2 provided on the nozzle plate CS eject the same color ink, and the nozzle NQ2 belonging to the nozzle row LQ2 provided on the nozzle plate CQ and the nozzle NS1 belonging to the nozzle row LS1 provided on the nozzle plate CS may eject the same color ink. Specifically, in this modification, in FIG. 9, the nozzle NQ1 belonging to the nozzle row LQ1 provided on the nozzle plate CQ and the nozzle NS2 belonging to the nozzle row LS2 provided on the nozzle plate CS eject yellow ink, and the nozzle NQ2 belonging to the nozzle row LQ2 provided on the nozzle plate CQ and the nozzle NS1 belonging to the nozzle row LS1 provided on the nozzle plate CS may eject cyan ink.

[0201] Note that, in this modification, similar to the second embodiment, it is assumed that the interval G is M times the interval R and the value M is M = 2. Therefore, the inkjet printer according to this modification can form the dots Dty and Dtc at the interval R in the X-axis direction and the Y-axis direction. That is, the inkjet printer according to this modification can form the dot Dtg at the interval R in the X-axis direction and the Y-axis direction.

[0202] 5.3. Modification 3 In the above-described embodiments and modifications, a case where the plate opening interval U[m1][m2] is equal to the nozzle row interval D1[m1][m2] and the nozzle row interval D2[m1][m2] was exemplified. However, the present invention is not limited to such an aspect. For example, the plate opening interval U[m1][m2] may be a different interval from the nozzle row interval D1[m1][m2] and the nozzle row interval D2[m1][m2].

[0203] FIG. 21 is an explanatory diagram showing the positional relationship between the M nozzle plates C included in the head module 2C according to this modified example and the fixed plate 26C. Note that FIG. 21 shows various positional relationships when the head module 2C is viewed in perspective from the -Z direction to the +Z direction. Also, in FIG. 21, the case where M = 4 is illustrated and described. The difference between this modified example and the first embodiment is that the head module 2C of this modified example includes a fixed plate 26C instead of the fixed plate 26 included in the head module 2 of the first embodiment. The fixed plate 26C of this modified example has the same structure as the fixed plate 26C that constitutes the head module 2V of the reference example shown in FIG. 22, which is mounted on an inkjet printer different from the inkjet printer 1 according to the first embodiment. In this modified example, as shown in FIG. 21, the plate opening interval U[m1][m2] is provided so as to be different from the nozzle row intervals D1[m1][m2] and D2[m1][m2]. Note that it is assumed that the nozzle row intervals D1[m1][m2] and D2[m1][m2] in this modified example are equal to the nozzle row intervals D1[m1][m2] and D2[m1][m2] in the first embodiment.

[0204] For example, in this modified example, the plate opening interval U[1][ma] is expressed as U[1][ma]=(M×ψ[ma])R. Here, the value ψ[ma] is a natural number larger than the value α. Also, in this modified example, similar to the first embodiment, it is assumed that the nozzle row interval D1[1][ma] satisfies D1[1][ma]=(M×β[ma]+γ[ma])R. In this case, in this modified example, the plate opening interval U[1][ma] and the nozzle row interval D1[1][ma] satisfy the relationship U[1][ma]:D1[1][ma]=M×ψ[ma]:M×β[ma]+γ[ma]. Here, for example, when the value M is 2, the value ma is 2, the value γ[2] is 1, and the relationship U[1][2]:D1[1][2]=EK1:O1 is satisfied. Here, the value EK1 is a positive even number, and the value O1 is a positive odd number satisfying O1>EK1. Note that the value EK1 may be an even number satisfying EK1>O1.

[0205] As described above, in the head module 2C according to the third modification, the plate opening W includes the plate opening W[1] and (M - 1) specific openings corresponding to (M - 1) specific nozzle plates. The plate opening W[1] exposes at least the nozzle row L1[1] and the nozzle row L2[1] among the nozzle plates C[1]. Among the (M - 1) specific openings, the plate opening W[ma] exposes at least the nozzle row L1[ma] among the nozzle plates C[ma]. The plate opening interval U[1][ma] between the center of the plate opening W[1] and the center of the plate opening W[ma] in the X-axis direction can be expressed as U[1][ma]:D1[1][ma]=M×ψ:M×β[ma]+γ[ma] by the value M, a natural number ψ of 1 or more, the value β[ma], and the value γ[ma]. That is, in this modification, since the plate opening interval does not depend on the nozzle row interval as in the first embodiment, it is possible to share the fixed plate 26C used in the reference example and the fixed plate 26C used in this modification, and it is possible to achieve a reduction in manufacturing cost by reducing the types of parts. In addition, in Modification 3, the plate opening W is an example of the "opening", the plate opening W[1] is an example of the "first opening", the plate opening W[ma] is an example of the "m-th specific opening", the nozzle plate C[ma] is an example of the "m-th specific nozzle plate", the nozzle row L1[ma] is an example of the "m-th specific nozzle row", the plate opening interval U[1][ma] is an example of the "interval PKT[m]", the nozzle row interval D1[1][ma] is an example of the "interval PT[m]", the nozzle plate C[1] is an example of the "first nozzle plate", the nozzle row L1[1] is an example of the "first nozzle row", the nozzle row L2[1] is an example of the "second nozzle row", the value β[ma] is an example of the "value βT[m]", and the value γ[ma] is an example of the "value γT[m]".

[0206] Further, in this modification, when M = 2, the plate opening W includes the plate opening W[1] and the plate opening W[2]. The plate opening W[1] exposes at least the nozzle row L1[1] and the nozzle row L2[1] in the nozzle plate C[1], and the plate opening W[2] exposes at least the nozzle row L1[2] in the nozzle plate C[2]. The plate opening interval U[1][2] between the center of the plate opening W[1] and the center of the plate opening W[2] in the X-axis direction can be expressed as PK1:P2 = EK1:O1 by a positive even value EK1 and a positive odd value O1. This is the feature of this modification. In addition, in this modification when M = 2, the plate opening W is an example of the "opening", the plate opening W[1] is an example of the "first opening", the plate opening W[2] is an example of the "second opening", the nozzle plate C[2] is an example of the "second nozzle plate", the nozzle row L1[2] is an example of the "third nozzle row", the plate opening interval U[1][2] is an example of the "interval PK1", the nozzle row interval D1[1][2] is an example of the "interval P2", the nozzle plate C[1] is an example of the "first nozzle plate", the nozzle row L1[1] is an example of the "first nozzle row", and the nozzle row L2[1] is an example of the "second nozzle row".

[0207] 5.4. Modification 4 In the above-described first embodiment, as shown in FIG. 2, the configuration in which the distribution flow path 221 is provided in the ink introduction member 22 has been exemplified. However, the distribution flow path 221 may be provided in the intermediate flow path member 23 or may be provided in the holder 25. Further, the intermediate flow path member 23 may be a part of the holder 25.

[0208] 5.5. Modification Example 5 In the above-described first embodiment, the main scanning direction is the X-axis direction and the sub-scanning direction is the Y-axis direction, and a serial printer in which the carriage 761 reciprocates in the X-axis direction which is the main scanning direction so that the recording paper PE and the head module 2 relatively move in the main scanning direction has been exemplified. However, the present invention is not limited to such a mode. It may be a line printer in which the main scanning direction is the Y-axis direction, the sub-scanning direction is the X-axis direction, and the width in the sub-scanning direction is equal to or greater than the paper width. In this case, the head module 2 which is a line head does not move, and the recording paper PE is conveyed in the Y-axis direction so that the recording paper PE and the head module 2 relatively move in the main scanning direction. By using the head module 2 according to the present invention, the same effect can be obtained by increasing the conveyance speed of the recording paper PE instead of the scanning speed of the carriage 761. Note that the head module 2 is installed so that the nozzle rows intersect in the main scanning direction, in the same manner as in the first embodiment described above. In this modification example, the nozzle rows intersect in the Y-axis direction. Therefore, the head module 2 of this modification example is used, for example, in a state where the head module 2 of the first embodiment is rotated 90 degrees with the Z-axis as the rotation axis.

[0209] 5.6. Modification Example 6 In the above-described second embodiment, as shown in FIG. 9, the case where the nozzle plates are arranged in the order of nozzle plates CQ[1], CQ[2], CS[1], CS[2] from the -X direction to the +X direction has been exemplified. However, the present invention is not limited to such a mode. The nozzle plates that eject two different colors of ink may be arranged in any order. That is, if the nozzle row interval DL, the nozzle row intervals DQ1[1][ma] and DS1[1][ma], and the interval DQS are set to satisfy DL:DQ1[1][ma](=DS1[1][ma]):DQS = E1:O1:E2, then, for example, in this modified example, the nozzle plate may be arranged in the order of nozzle plates CQ[1], CS[1], CQ[2], CS[2] from the -X direction to the +X direction. In other words, the nozzle plates C that eject different colors of ink may be arranged alternately. In this case, the value O1 satisfies O1>E2.

Explanation of Signs

[0210] 1... Inkjet printer, 2... Head module, 3... Print head chip, 4... Ink cartridge, 8... Control unit, N... Nozzle, C... Nozzle plate, W... Plate opening, Dt... Dot, 26... Fixed plate, 30... Wiring board, 33... Diaphragm, 220... Inlet, 221... Distribution channel, 251... Supply channel, 300... Drive circuit, 331... Piezoelectric element, 332... Piezoelectric element, 761... Carriage.

Claims

1. A head module having a first direction as a main scanning direction, comprising: a first head chip including a first nozzle plate provided with a first nozzle row for discharging liquid and a second nozzle row for discharging liquid; a second head chip including a second nozzle plate provided with a third nozzle row for discharging liquid; a fixing plate having a first opening for exposing at least the first nozzle row and the second nozzle row of the first nozzle plate and a second opening for exposing at least the third nozzle row of the second nozzle plate; wherein the first head chip and the second head chip have a common structure, a distance P1 between the first nozzle row and the second nozzle row in the first direction, and a distance P2 between the first nozzle row and the third nozzle row in the first direction are represented as P1:P2 = E1:O1 by a positive even number value E1 and a positive odd number value O1 satisfying O1>E1. A head module characterized by the above.

2. The first nozzle and the third nozzle are arranged at the same position in a second direction orthogonal to the first direction. The head module according to claim 1, characterized by the above.

3. The first nozzle row includes a plurality of nozzles for discharging liquid, the second nozzle row includes a plurality of nozzles for discharging liquid, in the second direction, between two adjacent nozzles among the plurality of nozzles included in the first nozzle row, one nozzle among the plurality of nozzles included in the second nozzle row is provided. The head module according to claim 2, characterized by the above.

4. The first head chip and the second head chip are fixed to the fixing plate such that, when the fixing plate is viewed in plan, the distance in the first direction between the center of the first head chip and the center of the second head chip is the distance P2. A distance PK1 between the center of the first opening and the center of the second opening in the first direction is represented as PK1:P2 = EK1:O1 by a positive even number value EK1 and the value O1. The head module according to any one of claims 1 to 3, characterized by the above.

5. It has a supply flow path for supplying liquid to the first head chip and the second head chip. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ and the distance in the first direction between the center of the first head chip and the center of the second head chip is the interval P2, a holder for holding the first head chip and the second head chip is provided, The head module according to any one of claims 1 to 4, characterized in that.

6. An inlet for introducing a liquid, communicating with the first nozzle and the third nozzle, and distributing the liquid introduced from the inlet to the first nozzle and the third nozzle, a distribution flow path, The head module according to any one of claims 1 to 5, characterized in that it comprises. le.

7. The head module according to any one of claims 1 to 6, a carriage for reciprocating the head module in the first direction and the direction opposite to the first direction, and, A liquid ejection device comprising.

8. The head module according to any one of claims 1 to 6, a transport mechanism for transporting a medium in the first direction, and, A liquid ejection device comprising.

9. A head module having a first direction as a main scanning direction, comprising a first nozzle row including a plurality of nozzles including a first nozzle for ejecting a liquid, and a plurality of nozzles including a second nozzle for ejecting a liquid a second nozzle row, and a third nozzle row including a plurality of nozzles including a third nozzle for ejecting a liquid, A head module comprising: a carriage for reciprocating the head module in the first direction and the direction opposite to the first direction, and, comprising, all the nozzles included in the first nozzle row, all the nozzles included in the second nozzle row, and all the nozzles included in the third nozzle row can eject liquid at the same timing, The distance P1 between the first nozzle row and the second nozzle row in the first direction, The distance P2 between the first nozzle row and the third nozzle row in the first direction, are a positive even value E1 and a positive odd value O1 satisfying O1>E1, and can be expressed as P1:P2 = E1:O1, A liquid ejection device characterized by that.

10. A head module having a first direction as a main scanning direction, comprising a first nozzle row including a plurality of nozzles including a first nozzle for ejecting a liquid, and a plurality of nozzles including a second nozzle for ejecting a liquid a second nozzle row, and a third nozzle row including a plurality of nozzles including a third nozzle for ejecting a liquid, A head module comprising: ​ ​ A transport mechanism for transporting a medium in the first direction, comprising All of the nozzles included in the first nozzle row and all of the nozzles included in the second nozzle row and all of the nozzles included in the third nozzle row are capable of discharging liquid at the same timing, and The distance P1 between the first nozzle row and the second nozzle row in the first direction, The distance P2 between the first nozzle row and the third nozzle row in the first direction, Are a positive even value E1 and a positive odd value O1 that satisfies O1>E1, P1:P2 = E1:O1, A liquid ejection device characterized by this.

11. The minimum distance in the first direction between two dots formed by the first nozzle is the distance obtained by dividing the distance P1 by the value E1 and also the distance obtained by dividing the distance P2 by the value O1, and is twice the distance P0, A liquid ejection device according to any one of claims 7 to 10, characterized by this.

12. The first nozzle, the second nozzle, and the third nozzle are capable of discharging liquid at the same timing, and A liquid ejection device according to claim 11, characterized by this.

13. The head module comprises a first drive element corresponding to the first nozzle, a second drive element corresponding to the second nozzle, and a third drive element corresponding to the third nozzle, and a common drive signal is supplied to the first drive element, the second drive element, and the third drive element, and A liquid ejection device according to any one of claims 7 to 12, characterized by this.

14. The first nozzle, the second nozzle, and the third nozzle discharge the same type of liquid, and 、 A liquid ejection device according to any one of claims 7 to 13, characterized by this.

15. The first nozzle, the second nozzle, and the third nozzle discharge the same type of liquid, and in a second direction orthogonal to the first direction, the distance between two adjacent nozzles among the plurality of nozzles included in the first nozzle row is twice the distance P0, and in the second direction orthogonal to the first direction, the minimum distance between the first nozzle and the second nozzle is the distance P0, and A liquid ejection device according to claim 11 or 12, characterized by this.

16. A head module with the first direction as the main scanning direction, including a first nozzle row including a plurality of nozzles that discharge liquid, and a second nozzle row including a plurality of nozzles that discharge liquid, including a first nozzle that discharges liquid A second nozzle row including and a third nozzle row including a plurality of nozzles that discharge a liquid, A head module including: A carriage that reciprocates the head module in the first direction and the direction opposite to the first direction, And, Comprising All of the nozzles included in the first nozzle row, all of the nozzles included in the second nozzle row, And all of the nozzles included in the third nozzle row are capable of discharging liquid at the same timing, And The interval P1 between the first nozzle row and the second nozzle row in the first direction, and the first The interval P2 between the first nozzle row and the third nozzle row in the direction, Are a value M that is a natural number of 3 or more, a value α that is a natural number of 1 or more, and a natural number that satisfies β > α With a value β that is P1:P2 = M×α:M×β + 1, A liquid ejection device characterized by that.

17. A head module having the first direction as the main scanning direction, the first nozzle for discharging liquid A first nozzle row including a plurality of nozzles, a second nozzle row including a plurality of nozzles Including a second nozzle for discharging liquid, and a third nozzle row including a plurality of nozzles including a third nozzle for discharging liquid, A head module including: A transport mechanism that transports a medium in the first direction, Comprising All of the nozzles included in the first nozzle row, all of the nozzles included in the second nozzle row, And all of the nozzles included in the third nozzle row are capable of discharging liquid at the same timing, And The interval P1 between the first nozzle row and the second nozzle row in the first direction, and the first The interval P2 between the first nozzle row and the third nozzle row in the direction, Are a value M that is a natural number of 3 or more, a value α that is a natural number of 1 or more, and a natural number that satisfies β > α With a value β that is P1:P2 = M×α:M×β + 1, A liquid ejection device characterized by that.

18. The minimum interval in the first direction between two dots formed by the first nozzle is The interval obtained by dividing the interval P1 by the value obtained by multiplying the value M and the value α, and The interval obtained by dividing the interval P2 by the value obtained by multiplying the value M and the value β and adding 1 thereto Is an interval M times the interval P0, The liquid ejection device according to claim 16 or 17, characterized by that.

19. The first nozzle, the second nozzle, and the third nozzle discharge the same type of liquid, In a second direction orthogonal to the first direction, a plurality of nozzles included in the first nozzle row Among them, the distance between two adjacent nozzles is n times the distance P0, In the second direction orthogonal to the first direction, the minimum distance between the first nozzle and the second nozzle Is the distance P0, The value n is a natural number indicating the number of nozzle rows provided in the first nozzle plate on which the first nozzle row and the second nozzle row are provided It is, The liquid ejection device according to claim 18, characterized by this.

20. A head module having the first direction as the main scanning direction, A first nozzle row including nozzles for ejecting liquid, A second nozzle row including nozzles for ejecting liquid, When the value M is a natural number of 3 or more, (M - 1) specific nozzle rows including nozzles for ejecting liquid And, Equipped with, When the value m is a natural number satisfying 1 ≦ m ≦ M - 1, The distance P1 between the first nozzle row and the second nozzle row in the first direction, and the first The distance PT[m] between the nozzle row and the m-th specific nozzle row among the (M - 1) specific nozzle rows in the direction Is, The value M, a value α that is a natural number of 1 or more, a value βT[m] that is a natural number satisfying βT[m] > α, and a value m1 that is a natural number satisfying 1 ≦ m1 ≦ M - 1, and a value m2 that is a natural number satisfying 1 ≦ m2 ≦ M - 1 And m1 ≠ m2, when 0 < γT[m] ≦ M - 1 is satisfied and A value γT[m] that is a natural number satisfying γT[m1] ≠ γT[m2], P1: PT[m] = M×α: M×βT[m] + γT[m], which can be expressed as A head module characterized by this.

21. The head module according to claim 20, And a carriage that reciprocates the head module in the first direction and the opposite direction of the first direction And, A liquid ejection device comprising.

22. The head module according to claim 20, And a transport mechanism for transporting a medium in the first direction And, A liquid ejection device comprising.

23. The first nozzle row includes a first nozzle for ejecting liquid, The second nozzle row includes a second nozzle for ejecting liquid, Each of the (M - 1) specific nozzle rows includes a specific nozzle for ejecting liquid, The first nozzle, the second nozzle, and the (M - 1) specific nozzles corresponding to the (M - 1) specific nozzle rows Eject the same type of liquid, The minimum distance in the first direction between two dots formed by the first nozzle is the front An interval obtained by dividing the interval P1 by a value obtained by multiplying the stored value M by the value α, and an interval obtained by dividing the interval PT[m] by a value obtained by adding the value γT[m] to a value obtained by multiplying the value M by the value βT[m], is an interval that is M times the interval P0, In a second direction orthogonal to the first direction, the interval between two adjacent nozzles among the plurality of nozzles included in the first nozzle row is n times the interval P0, In the second direction orthogonal to the first direction, the minimum interval between the first nozzle and the second nozzle is the interval P0, The value n is a natural number indicating the number of nozzle rows provided in the first nozzle plate on which the first nozzle row and the second nozzle row are provided, The liquid discharge device according to claim 21 or 22, characterized in that.

24. A head module having a first direction as a main scanning direction, A first nozzle row including a plurality of nozzles including a first nozzle for discharging liquid, A second nozzle row including a plurality of nozzles including a second nozzle for discharging liquid, A third nozzle row including a plurality of nozzles including a third nozzle for discharging liquid, Comprising, All the nozzles included in the first nozzle row, all the nozzles included in the second nozzle row, And all the nozzles included in the third nozzle row can discharge liquid at the same timing, A first dot formed by the liquid discharged by the first nozzle at a first timing, and the first nozzle The interval in the first direction between the second dot formed by the liquid discharged at the second timing when the liquid can be first discharged after the first timing is defined as the first interval, and the third dot formed by the liquid discharged by the second nozzle at the first timing The interval in the first direction between the first dot is defined as the second interval, and the fourth dot formed by the liquid discharged by the third nozzle at the first timing The interval in the first direction between the first dot is defined as the third interval. When the second interval is an integral multiple of the first interval and the third interval is an interval different from an integral multiple of the first interval, the first nozzle, the second nozzle, and the third nozzle are provided, A head module characterized by that.

25. The head module according to claim 24, A carriage that reciprocates the head module in the first direction and the opposite direction of the first direction, A liquid discharge device comprising. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

26. The head module according to claim 24, and a transport mechanism that transports a medium in the first direction, A liquid ejection device comprising:

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