LIQUID EJECTION APPARATUS AND METHOD FOR CONTROLLING LIQUID EJECTION APPARATUS

Abstract

To solve such a problem that there is such a risk that thickened ink near a nozzle diffuses to a pressure chamber side when the fine vibration is performed on a non-use discharge part group that is not used in printing.SOLUTION: A liquid discharge device 100 comprises a plurality of discharge part groups constituting a nozzle array 12 that can discharge ink. When setting the discharge part group that can discharge ink that is used as a use discharge part group and the discharge part group that can discharge ink that is not used as a non-use discharge part group in printing on a sheet P, a control unit 90 supplies a discharge pulse Pep in a period in which ink is discharged to a drive element E of the use discharge part group in the printing operation for performing the printing in a printing mode with the non-use nozzle group that does not use either ink of a plurality of inks, supplies a fine vibration pulse Pbp in printing in a period in which the ink is not discharged, and does not supply a fine vibration pulse Pb even in a period in which the ink is not discharged to the drive element E of the non-use discharge part group.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus and a method for controlling the liquid ejection apparatus. [Background technology]

[0002] Patent Document 1 discloses an inkjet printer, which is an example of a liquid ejection device that includes a plurality of nozzles and ejects ink, which is an example of a liquid contained in a pressure chamber connected to each nozzle, from the nozzles to print on a medium. In such inkjet printers, for example, thickening of the ink due to evaporation of water from the nozzle openings is a problem. Patent Document 1 discloses a configuration that reduces thickening of the ink near the nozzles by performing micro-vibrations that vibrate the ink near the nozzle openings to an extent that the ink is not ejected from the nozzles. In addition, this printer includes a plurality of nozzles capable of ejecting black ink, which is an example of a nozzle group, and a plurality of nozzles capable of ejecting color inks that are different colors from the black ink, so that multi-color printing can be performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-1951 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the liquid ejection device described in Patent Document 1, for example, even when color printing is performed without ejecting ink from the nozzle group capable of ejecting black ink, micro-vibrations are applied to the black ink ejection unit group having a plurality of nozzles that constitute the nozzle group capable of ejecting black ink. In this case, in the black ink ejection unit group, which is an unused ejection unit group that is not used in printing, applying micro-vibrations may cause thickened ink near the nozzles to diffuse toward the pressure chamber side. [Means for solving the problem]

[0005] The liquid ejection device includes a plurality of ejection sections each having a nozzle capable of ejecting a liquid, a pressure chamber communicating with the nozzle, and a drive element that generates a pressure fluctuation in the liquid in the pressure chamber by being supplied with a drive pulse, a drive circuit capable of supplying drive pulses to the drive element of the ejection section, the drive pulse including an ejection pulse that ejects the liquid from the nozzle, and a micro-vibration pulse that vibrates an air-liquid interface in the nozzle when the liquid is not ejected from the nozzle, and a control section, wherein the control section controls the drive circuit based on a print job for executing a printing operation that prints on a medium, thereby ejecting the liquid from the nozzle to execute the printing operation, and the plurality of ejection sections form a plurality of ejection section groups each having a plurality of the nozzles that constitute a nozzle group capable of ejecting any one of a plurality of types of the liquid, and in the printing on the medium, the ejection section group capable of ejecting the liquid to be used is called a used ejection section group, and the ejection section group capable of ejecting the liquid not to be used is called a non-used ejection section group. When the printing is in a printing mode without unused nozzle groups in which the multiple types of liquids are used, the control unit controls the drive circuit to supply the ejection pulse to the drive elements of the unused ejection unit groups during a period in which the liquid is ejected and to supply the micro-vibration pulse during a period in which the liquid is not ejected, in the printing operation to perform the printing in the printing mode without unused nozzle groups; when the printing is in a printing mode with unused nozzle groups in which no liquid of the multiple types of liquids is used, the control unit controls the drive circuit to supply the ejection pulse to the drive elements of the unused ejection unit groups during a period in which the liquid is ejected and to supply the micro-vibration pulse during a period in which the liquid is not ejected, in the printing operation to perform the printing in the printing mode with unused nozzle groups.

[0006] A control method for a liquid ejection device includes a plurality of ejection units each having a nozzle capable of ejecting a liquid, a pressure chamber communicating with the nozzle, and a drive element that generates a pressure fluctuation in the liquid in the pressure chamber by being supplied with a drive pulse, the plurality of ejection units forming a plurality of ejection unit groups each having a plurality of nozzles constituting a nozzle group capable of ejecting any one of a plurality of types of the liquid, and a drive pulse including an ejection pulse that ejects the liquid from the nozzle and a micro-vibration pulse that vibrates an air-liquid interface in the nozzle when the liquid is not ejected from the nozzle is supplied to the drive element, the control method for a liquid ejection device performing a printing operation for printing on a medium by supplying a drive pulse to the drive element, the drive pulse including an ejection pulse that ejects the liquid from the nozzle and a micro-vibration pulse that vibrates an air-liquid interface in the nozzle when the liquid is not ejected from the nozzle, the control method comprising the steps of: When the printing is in a printing mode without unused nozzle groups in which the multiple types of liquids are used, in the printing operation to perform the printing in the printing mode without unused nozzle groups, the ejection pulse is supplied to the drive elements of the used ejection unit group during a period in which the liquid is ejected, and the micro-vibration pulse is supplied during a period in which the liquid is not ejected; when the printing is in a printing mode with unused nozzle groups in which any of the multiple types of liquids is not used, in the printing operation to perform the printing in the printing mode with unused nozzle groups, the ejection pulse is supplied to the drive elements of the used ejection unit group during a period in which the liquid is ejected, and the micro-vibration pulse is supplied during a period in which the liquid is not ejected, and the micro-vibration pulse is not supplied to the drive elements of the unused ejection unit group even during a period in which the liquid is not ejected. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram showing a schematic configuration of a liquid ejection device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing the configuration of a liquid ejection head. [Diagram 3] FIG. [Figure 4] FIG. 4 is a waveform diagram of a micro-vibration driving signal. [Diagram 5] FIG. 4 is a waveform diagram of a flushing drive signal. [Figure 6] 6 is a flowchart showing a process flow when a printing operation is executed. [Figure 7] FIG. 11 is a block diagram showing another embodiment in which the specifications of the liquid ejection device are partially changed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the present invention will be described based on an embodiment. In each drawing, the same members are given the same reference numerals, and duplicated explanations will be omitted.

[0009] In each figure, X, Y, and Z represent three spatial axes that are mutually orthogonal. In this specification, the directions along these axes are the X-axis direction, the Y-axis direction, and the Z-axis direction. When specifying a direction, the positive direction is "+" and the negative direction is "-", and the direction notation is both positive and negative, with the direction indicated by the arrow in each figure being the + direction and the opposite direction to the arrow being the - direction. The Z direction indicates the vertical direction, with the +Z direction being vertically downward and the -Z direction being vertically upward. Furthermore, the three spatial axes X, Y, and Z that are not limited to positive and negative directions will be described as the X-axis, Y-axis, and Z-axis.

[0010] 1. Embodiment 1 In this embodiment, the liquid ejection device 100 is configured as an inkjet printer, and prints images and characters by ejecting ink onto paper P. Paper P is an example of a medium, and ink is an example of a liquid. Note that, instead of paper P, any type of medium, such as a resin film or fabric, may be used as the target onto which ink is ejected.

[0011] As shown in FIG. 1, the liquid ejection device 100 includes a liquid ejection head 10, a liquid supply unit 20, a conveyance unit 30, a maintenance unit 50, an input / output unit 80, and a control unit 90. An external device 200 is connected to the liquid ejection device 100 by wire or wirelessly. The external device 200 is, for example, an electronic device that handles images, such as a computer, a digital camera, or a mobile phone. The external device 200 sequentially supplies print jobs J to the liquid ejection device 100. The print job J is an instruction for a series of operations for printing images and characters on paper P. For example, in the print job J, various conditions such as the number of prints, duty, print mode (color / monochrome), size of paper P (Pw / Pn), type of paper P (photo paper / plain paper), image quality mode (high image quality / normal image quality / low image quality), and direction of paper P conveyed by the conveyance unit 30 (horizontal / vertical) are instructed.

[0012] The liquid supply unit 20 supplies ink to the liquid ejection head 10. The liquid supply unit 20 has a liquid storage unit holding unit 22 and a connection flow path 23. The liquid storage unit holding unit 22 holds the liquid storage unit 21. The liquid storage unit holding unit 22 of this embodiment detachably holds a plurality of liquid storage units 21a, 21b, 21c, and 21d. The liquid storage units 21a, 21b, 21c, and 21d respectively hold black ink, yellow ink, magenta ink, and cyan ink of different colors. The black ink, yellow ink, magenta ink, and cyan ink are examples of a plurality of types of liquid. The connection flow path 23 connects the liquid storage unit holding unit 22 and the liquid ejection head 10 so that the ink in the liquid storage unit 21 held in the liquid storage unit holding unit 22 can be supplied to the liquid ejection head 10.

[0013] The transport unit 30 transports the paper P in a transport direction. As shown in FIG. 1, the transport direction in this embodiment is the +Y direction and the -Y direction. The transport unit 30 includes a transport rod 34 to which three transport rollers 32 are attached, and a transport motor 36 that rotates the transport rod 34. The transport motor 36 rotates the transport rod 34, causing the multiple transport rollers 32 to rotate and transport the paper P in the +Y direction in the transport direction. The number of transport rollers 32 is not limited to three and may be any number. Also, a configuration may be provided with multiple transport units 30.

[0014] The maintenance section 50 performs maintenance of the liquid ejection head 10. The maintenance section 50 has a maintenance unit holding section 51, a cap 52, a wiper 53, a waste liquid tube 54, a suction pump 55, and a waste liquid collection section 56. The maintenance unit holding section 51 holds the cap 52 and the wiper 53. The maintenance unit holding section 51 is movable in the Y-axis direction.

[0015] The cap 52 comes into contact with the nozzle surface 11 of the liquid ejection head 10, which will be described later, to perform capping, forming a capping space in which a plurality of nozzles N are open. When a printing operation is not being performed and the liquid ejection head 10 is in a standby state, the maintenance unit 50 performs capping to suppress evaporation of moisture from the ink through the openings of the nozzles N of the liquid ejection head 10. The maintenance unit 50 performs maintenance of the liquid ejection head 10 by performing capping.

[0016] The cap 52 is movable among a separated position where it does not face the nozzle surface 11 of the liquid ejection head 10, a capping position where it comes into contact with the nozzle surface 11 and caps it, and a facing position where it faces the nozzle surface 11 but does not come into contact with it. The cap 52 at the separated position is located on the +Y direction side of the printing position where the liquid ejection head 10 shown in FIG. 1 prints on the paper P. The cap 52 at the capping position and the facing position is located in a position where it faces the nozzle surface 11 of the liquid ejection head 10 at the printing position, and is located on the -Y direction side of the separated position. In addition, the cap 52 at the capping position and the facing position is located between the liquid ejection head 10 and the paper P in the Z axis direction when the paper P is in a printable area on the +Z direction side of the liquid ejection head 10.

[0017] The cap 52 communicates with a waste liquid collecting unit 56 that collects waste liquid via a waste liquid tube 54. A suction pump 55 is provided in the waste liquid tube 54 to suck the capping space formed by the cap 52. The maintenance unit 50 drives the suction pump 55 while the cap 52 is in the capping position to discharge ink from the multiple nozzles N into the capping space, thereby maintaining the ink in the liquid ejection head 10 in a good condition. The maintenance unit 50 performs maintenance of the liquid ejection head 10 by sucking the ink in the liquid ejection head 10 through the nozzles N. The ink discharged into the capping space is collected in the waste liquid collecting unit 56 via the waste liquid tube 54.

[0018] Furthermore, the cap 52 receives ink ejected from the nozzles N in a flushing operation, which will be described later, at the opposing position. That is, the cap 52 in this embodiment also functions as a flushing receiver FLR. The flushing operation is a maintenance operation in which ink is ejected from the nozzles N of the liquid ejection head 10 for the purpose of maintaining the state of the ink inside the liquid ejection head 10 in a good state. Note that the maintenance unit 50 may have a flushing receiver FLR, separate from the cap 52, that receives ink ejected from the nozzles N in the flushing operation.

[0019] The maintenance section 50 performs maintenance of the liquid ejection head 10 by wiping the nozzle surface 11 of the liquid ejection head 10 with the wiper 53. The wiper 53 moves in the Z-axis direction between a non-contact position where it does not contact the nozzle surface 11 and a wiping position where it can contact the nozzle surface 11. In this embodiment, with the wiper 53 in the wiping position, the maintenance unit holding section 51 that holds the wiper 53 moves in the Y-axis direction to wipe the nozzle surface 11.

[0020] The input / output unit 80 has a display unit 81 and an operation unit 82. The operation unit 82 is an example of an input unit. The display unit 81 is an example of a notification unit that displays guidance for operating the liquid ejection device 100 and notifies information related to the liquid ejection device 100. A user can perform various operations on the liquid ejection device 100 by operating the operation unit 82 while referring to the contents displayed on the display unit 81. Note that if the display unit 81 is configured with a liquid crystal display module having a touch panel function and has a function as an operation unit for making various settings for the liquid ejection device 100, the operation unit 82 may be omitted.

[0021] The user can input various conditions of the above-mentioned print job J, for example, by operating the operation unit 82. Thus, the print job J is input to the control unit 90 from the external device 200, and is also input to the control unit 90 from the input / output unit 80 in response to a user operation. For example, in a copy operation in which an image scanned by a scanner (not shown) is printed on paper P, or in a print operation in which an image stored in a recording medium such as a memory card or a USB (Universal Serial Bus) memory is printed, the user may input the print job J by operating the input / output unit 80.

[0022] The control unit 90 controls the entire liquid ejection device 100. For example, the control unit 90 controls the transport operation of the transport unit 30 along the transport direction of the paper P, the ink ejection operation from the nozzles N of the liquid ejection head 10, the maintenance operation of the liquid ejection head 10 by the maintenance unit 50, and the control of the liquid ejection device 100 based on a user instruction by the input / output unit 80 and notifications to the user.

[0023] The control unit 90 includes, for example, a control device 91 and a storage device 92. The control device 91 is a single or multiple processors that execute various calculations and controls. Specifically, the control device 91 is configured by one or more types of processors, such as a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), or a field programmable gate array (FPGA). The storage device 92 is a single or multiple memories that store programs executed by the control device 91 and various types of data used by the control device 91. For example, a recording medium such as a semiconductor recording medium or a magnetic recording medium is used as the storage device 92. A combination of multiple types of recording media may be used as the storage device 92.

[0024] The liquid ejection head 10 has a plurality of nozzles N that eject ink. The plurality of nozzles N are opened on a nozzle surface 11, which is a surface on the +Z direction side of the liquid ejection head 10. The plurality of nozzles N are arranged at equal intervals in one direction to form a nozzle row 12. The liquid ejection head 10 of this embodiment is a so-called line head. Therefore, the nozzle row 12 is aligned along the X-axis direction, and the dimension between the nozzles N at both ends in the X-axis direction among the plurality of nozzles N that form the nozzle row 12 is longer than the width dimension of the paper P. The nozzle row 12 is an example of a nozzle group. In this embodiment, the nozzle row 12 includes a plurality of nozzle rows 12a, 12b, 12c, and 12d. The plurality of nozzle rows 12a, 12b, 12c, and 12d are arranged in the order of the nozzle rows 12a, 12b, 12c, and 12d, with an interval in the Y-axis direction, from the -Y direction side to the +Y direction side.

[0025] In this embodiment, the multiple nozzles N forming the nozzle row 12a eject black ink supplied from the liquid storage section 21a to the liquid ejection head 10. The multiple nozzles N forming the nozzle row 12b eject yellow ink supplied from the liquid storage section 21b to the liquid ejection head 10. The multiple nozzles N forming the nozzle row 12c eject magenta ink supplied from the liquid storage section 21c to the liquid ejection head 10. The multiple nozzles N forming the nozzle row 12d eject cyan ink supplied from the liquid storage section 21d to the liquid ejection head 10.

[0026] Black ink, yellow ink, magenta ink, and cyan ink are examples of multiple types of liquid. Furthermore, yellow ink, magenta ink, and cyan ink are examples of color inks that are different colors from black ink. Furthermore, black ink and color inks that are different colors from black ink are examples of multiple types of liquid. The multiple nozzle rows 12a, 12b, 12c, and 12d are examples of nozzle groups that can eject any one of the multiple types of liquid. The nozzle row 12a is a black ink nozzle group that can eject black ink. Each of the nozzle rows 12b, 12c, and 12d is an example of a color ink nozzle group that can eject color ink.

[0027] In addition, the nozzles N of the liquid ejection head 10 of this embodiment form a nozzle section Hn provided in an area corresponding to the paper Pn, which is smaller in size than the paper Pw, on the nozzle surface 11 when the paper P is transported in the vertical direction as shown in FIG. 1, and a nozzle section Hw provided in an area adjacent to the nozzle section Hn on the -X direction side. The nozzles N forming the nozzle section Hn are used when printing is performed by ejecting ink onto the paper Pw and Pn. The nozzles N forming the nozzle section Hw are used when printing is performed by ejecting ink onto the paper Pw, and are not used when printing is performed by ejecting ink onto the paper Pn. The dimension in the X-axis direction when the paper Pn is transported in the horizontal direction is the same as the dimension in the X-axis direction when the paper Pw is transported in the vertical direction.

[0028] 2, the liquid ejection head 10 has a plurality of nozzles N, a plurality of pressure chambers C, a plurality of driving elements E, and a driving circuit 15. The nozzles N, the pressure chambers C, and the driving elements E constitute an ejection section 13 capable of ejecting ink. Thus, the liquid ejection head 10 has a plurality of ejection sections 13. It can be said that the plurality of ejection sections 13 form, for example, a black ink ejection section group having a plurality of nozzles N constituting the nozzle row 12a, a yellow ink ejection section group having a plurality of nozzles N constituting the nozzle row 12b, a magenta ink ejection section group having a plurality of nozzles N constituting the nozzle row 12c, and a cyan ink ejection section group having a plurality of nozzles N constituting the nozzle row 12d.

[0029] It can also be said that the multiple ejection units 13 form a black ink ejection unit group having the multiple nozzles N constituting the nozzle row 12a, and a color ink ejection unit group having the multiple nozzles N constituting the nozzle rows 12b, 12c, and 12d. In this case, it can be said that the multiple ejection units 13 form multiple ejection unit groups. In addition, in the following description, a group of ejection units having nozzles N capable of ejecting ink used in printing images and characters on paper P may be referred to as an active ejection unit group, and a group of ejection units having nozzles N capable of ejecting ink not used in the printing may be referred to as an active ejection unit group.

[0030] A pressure chamber C and a driving element E are formed for each nozzle N. The pressure chamber C is a space that leads to the nozzle N. Ink supplied from the liquid storage section 21 is filled into the multiple pressure chambers C of the liquid ejection head 10. The driving element E varies the pressure of the ink in the pressure chamber C. For example, a piezoelectric element that changes the volume of the pressure chamber C by deforming the wall surface of the pressure chamber C, or a heating element that generates air bubbles in the pressure chamber C by heating the ink in the pressure chamber C, is used as the driving element E. The driving element E varies the pressure of the ink in the pressure chamber C, so that the ink in the pressure chamber C is ejected from the nozzle N. If a state in which ink is not ejected from the nozzle N of the liquid ejection head 10 continues, the ink in the nozzle N becomes more viscous due to evaporation of moisture through the opening of the nozzle N.

[0031] The drive circuit 15 drives each of the multiple drive elements E under the control of the control unit 90. The drive circuit 15 of this embodiment supplies a drive pulse P of a drive signal D to each of the multiple drive elements E for each unit period U. The drive circuit 15 may be provided outside the liquid ejection head 10.

[0032] The control unit 90 controls the drive circuit 15 based on a print job J input to print an image or text on a paper P, thereby ejecting ink from the nozzles N of the liquid ejection head 10, thereby executing a printing operation for printing an image or text on the paper P. The control unit 90 also controls the drive circuit 15 to execute a micro-vibration operation for vibrating the ink in the nozzles N without ejecting it. The control unit 90 also controls the drive circuit 15 to execute a flushing operation for ejecting ink from the nozzles N for the purpose of maintaining the state of the ink in the liquid ejection head 10. The flushing operation includes an active nozzle group flushing operation for ejecting ink from the nozzles N of the active ejection unit group for the purpose of maintaining the state of the ink in the nozzles N of the active ejection unit group and the pressure chambers C of the active ejection unit group, and an unused nozzle group flushing operation for ejecting ink from the nozzles N of the unused ejection unit group for the purpose of maintaining the state of the ink in the nozzles N of the unused ejection unit group and the pressure chambers C of the active ejection unit group.

[0033] The control unit 90 supplies a plurality of signals, including a control signal S and a drive signal D, to the drive circuit 15. The control signal S is a signal that instructs each of the plurality of nozzles N whether or not to eject ink for each period of a predetermined length (hereinafter referred to as a "unit period") U. The drive signal D is a voltage signal that varies with a period of the unit period U. In this embodiment, the drive signal D includes a drive signal De, a drive signal Dbm, and a drive signal Dfn. The drive signal Dbm includes a non-printing micro-vibration pulse Pbm. The drive signal Dfn includes a flushing pulse Pfn.

[0034] If the in-print period is defined as the period during which ink is ejected from any of the nozzles N of the liquid ejection head 10 to print images or characters onto the paper P, the printing operation includes a non-print period from when the liquid ejection head 10 is released from its capped standby state to when printing begins, and a non-print period from when printing ends to when the liquid ejection head 10 is capped and enters a standby state. The drive signal De is supplied to the liquid ejection head 10 during the in-print period, and the drive signals Dbm and Dfn are supplied to the drive circuit 15 during the non-print period.

[0035] The non-printing period from when the liquid ejection head 10 is released from the capped standby state to when printing starts is also called the pre-printing period. The printing area of ​​the paper P where images and characters are printed is located at the printable position on the +Z direction side of the nozzle surface 11 of the liquid ejection head 10. The period during which the printing area of ​​the paper P is not at the printable position is the non-printing period because images cannot be printed. For example, in a printing operation performed based on a print job J with multiple sheets to be printed, the period from when the printing area of ​​the printed paper P is transported in the +Y direction from the printable position to when the printing area of ​​the next transported paper P is transported to the printable position is the non-printing period. Also, even if the printing area of ​​the paper P is at the printable position, the period during which the cap 52 is at the capping position facing the nozzle surface 11 and at the opposing position is the non-printing period.

[0036] As shown in FIG. 3, in this embodiment, the driving signal De supplied by the control unit 90 to the driving circuit 15 during the in-print period includes an ejection pulse Pep and an in-print micro-vibration pulse Pbp for each unit period Ue. The ejection pulse Pep is a driving pulse P supplied by the driving circuit 15 to the driving element E so that ink is ejected from the nozzle N during the in-print period. Specifically, the ejection pulse Pep includes a section s1, a section s2, a section s3, a section s4, and a section s5. The section s1 is a section in which the potential decreases from a predetermined reference potential V0. The decrease in potential corresponds to a direction in which the volume of the pressure chamber C is increased. The section s2 is a section in which the potential at the end of the section s1 is maintained. The section s3 is a section in which the potential increases from the potential of the section s2 to a potential exceeding the reference potential V0. The increase in potential corresponds to a direction in which the volume of the pressure chamber C is decreased. The section s4 is a section in which the potential at the end of the section s3 is maintained. In section s5, the potential drops from the potential in section s4 to the reference potential V0.

[0037] The supply of the ejection pulse Pep operates the driving element E, and the volume of the ink droplet ejected from the nozzle N depends on the voltage A1 of the ejection pulse Pep. Specifically, the larger the absolute value of the voltage A1, the larger the volume of the ink droplet ejected from the nozzle N. For this reason, for example, a plurality of drive signals De with different voltages A1 of the ejection pulse Pep may be provided, and the control unit 90 may supply the plurality of drive signals De to the drive circuit 15 to eject ink droplets of different volumes from the nozzle N.

[0038] The in-print micro-vibration pulse Pbp is a drive pulse P that the drive circuit 15 supplies to the drive element E in order to generate micro-vibrations in the ink in the pressure chamber C without ejecting ink from the nozzle N during the in-print period. The in-print micro-vibration pulse Pbp is an example of the micro-vibration pulse Pb. Specifically, the in-print micro-vibration pulse Pbp includes a section s6, a section s7, and a section s8. Section s6 is a section in which the potential drops from the reference potential V0 to the potential Vbp. Section s7 is a section in which the potential Vbp at the end of section s6 is maintained. Section s8 is a section in which the potential rises from the potential Vbp in section s7 to the reference potential V0.

[0039] The waveform of the in-print micro-vibration pulse Pbp is changed as appropriate. The waveform of the in-print micro-vibration pulse Pbp is not limited to the trapezoidal pulse shown in Fig. 3, and for example, a rectangular pulse may be adopted as the in-print micro-vibration pulse Pbp. In other words, the waveform of the in-print micro-vibration pulse Pbp in the drive signal De is not limited to the waveform shown in Fig. 3 and may be changed arbitrarily as long as it is a waveform that vibrates the meniscus formed by the ink in the nozzle N to such an extent that the ink in the pressure chamber C is not ejected from the nozzle N. The meniscus is the gas-liquid interface between the ink in the nozzle N and the atmosphere.

[0040] The magnitude of the meniscus vibration caused by the micro-vibration during printing depends on the voltage A2 of the micro-vibration pulse Pbp during printing. The voltage A2 corresponds to the potential difference between the maximum potential and the minimum potential of the micro-vibration pulse Pbp during printing, that is, the potential difference between the potential Vbp and the reference potential V0 in FIG. 3. Specifically, the greater the absolute value of the voltage A2, the greater the meniscus vibration caused by the micro-vibration during printing. The control unit 90 can control the voltage A2 of the micro-vibration pulse Pbp during printing.

[0041] As shown in FIG. 4, in this embodiment, the driving signal Dbm supplied by the control unit 90 to the driving circuit 15 during the non-printing period includes a non-printing micro-vibration pulse Pbm for each unit period Ubm. The non-printing micro-vibration pulse Pbm is a driving pulse P supplied by the driving circuit 15 to the driving element E in order to generate micro-vibrations in the ink in the pressure chamber C without ejecting ink from the nozzle N during the non-printing period. The non-printing micro-vibration pulse Pbm is an example of the micro-vibration pulse Pb. Specifically, the non-printing micro-vibration pulse Pbm includes a section s9, a section s10, and a section s11. The section s9 is a section in which the potential decreases from the reference potential V0 to the potential Vbm. The section s10 is a section in which the potential Vbm at the end of the section s9 is maintained. The section s11 is a section in which the potential increases from the potential Vbm in the section s10 to the reference potential V0.

[0042] The waveform of the non-printing micro-vibration pulse Pbm is changed as appropriate. The waveform of the non-printing micro-vibration pulse Pbm is not limited to the trapezoidal pulse shown in Fig. 4, and for example, a rectangular pulse may be adopted as the non-printing micro-vibration pulse Pbm. That is, the waveform of the non-printing micro-vibration pulse Pbm in the driving signal Dbm is not limited to the waveform shown in Fig. 4 and may be changed arbitrarily as long as it is a waveform that vibrates the meniscus formed by the ink in the nozzle N to such an extent that the ink in the pressure chamber C is not ejected from the nozzle N.

[0043] The magnitude of the meniscus vibration caused by the non-printing micro vibration depends on the voltage A3 of the non-printing micro vibration pulse Pbm. The voltage A3 corresponds to the potential difference between the highest potential and the lowest potential of the non-printing micro vibration pulse Pbm, that is, the potential difference between the potential Vbm and the reference potential V0 in FIG. 4. Specifically, the greater the absolute value of the voltage A3, the greater the magnitude of the meniscus vibration caused by the non-printing micro vibration. The control unit 90 can control the voltage A3 of the non-printing micro vibration pulse Pbm. The absolute value of the voltage A3 of the non-printing micro vibration pulse Pbm in this embodiment is set to be greater than the absolute value of the voltage A2 of the in-printing micro vibration pulse Pbp. Therefore, in this embodiment, the meniscus vibration caused by the non-printing micro vibration is greater than the meniscus vibration caused by the in-printing micro vibration.

[0044] The drive circuit 15 supplies a non-printing micro-vibration pulse Pbm to each of the multiple drive elements E for each unit period Ubm during the non-printing period including the pre-printing period described above. By operating the drive element E by supplying the non-printing micro-vibration pulse Pbm, micro-vibrations are generated in the ink in the nozzle N corresponding to the drive element E. The ink in the nozzle N is appropriately stirred by the micro-vibration, thereby reducing local thickening in the vicinity of the nozzle N. Note that the standby state in which the liquid ejection head 10 is capped corresponds to the non-printing period, but normally the control unit 90 does not execute the micro-vibration operation.

[0045] 5, in this embodiment, when performing a flushing operation, the drive signal Dfn supplied by the control unit 90 to the drive circuit 15 includes a flushing pulse Pfn for each unit period Ufn. The flushing pulse Pfn is a drive pulse P supplied by the drive circuit 15 to the drive element E so as to eject ink from the nozzle N. The flushing pulse Pfn is an example of a flushing pulse Pf. The flushing pulse Pfn is also included in the ejection pulse.

[0046] Specifically, the flushing pulse Pfn includes sections s12, s13, s14, s15, and s16. Section s12 is a section in which the potential decreases from a predetermined reference potential V0. The decrease in potential corresponds to a direction in which the volume of the pressure chamber C increases. Section s13 is a section in which the potential at the end of section s12 is maintained. Section s14 is a section in which the potential increases from the potential of section s13 to a potential higher than the reference potential V0. The increase in potential corresponds to a direction in which the volume of the pressure chamber C decreases. Section s15 is a section in which the potential at the end of section s14 is maintained. Section s16 is a section in which the potential decreases from the potential of section s15 to the reference potential V0.

[0047] The volume of the ink droplets ejected from the nozzle N depends on the voltage A4 of the flushing pulse Pfn when the drive element E operates in response to the supply of the flushing pulse Pfn. Specifically, the volume of the ink droplets ejected from the nozzle N increases as the absolute value of the voltage A4 increases. For this reason, for example, a drive signal Dfs including a flushing pulse Pfs whose voltage is smaller than the voltage A4 is provided. The volume of the ink droplets ejected from the nozzle N when the drive circuit 15 supplies the flushing pulse Pfs to the drive element E is smaller than the volume of the ink droplets ejected from the nozzle N when the drive circuit 15 supplies the flushing pulse Pfn to the drive element E. As a result, the control unit 90 may perform a flushing operation in which the amount of ink ejected from the nozzle N is smaller by supplying the drive signal Dfs to the drive circuit 15, compared to the case where the drive signal Dfn is supplied to the drive circuit 15.

[0048] In a printing operation, when a flushing operation needs to be performed as a maintenance operation immediately after the liquid ejection head 10 is released from capping before the start of printing or immediately before the liquid ejection head 10 is capped after printing is completed, the drive circuit 15 supplies flushing pulses Pfn a predetermined number of times to each of the multiple drive elements E. By operating the drive element E a predetermined number of times by supplying the flushing pulses Pfn, ink droplets are ejected a predetermined number of times from the nozzle N corresponding to the drive element E. In this way, the flushing operation is performed as a maintenance operation that is executed either immediately after the capping is released before the start of printing or immediately before the capping after printing is completed. The flushing operation is performed on the cap 52 that is disposed at the opposing position.

[0049] Furthermore, during the printing operation, each time a preset time elapses, the driving circuit 15 supplies a flushing pulse Pfn a preset number of times to each of the multiple driving elements E. By operating the driving element E a preset number of times by supplying the flushing pulse Pfn, ink droplets are ejected a preset number of times from the nozzle N corresponding to the driving element E. As a result, during the printing operation, the flushing operation is performed at preset time intervals between flushing operations.

[0050] In the following description, the flushing operation performed every time a preset time elapses during a printing operation is referred to as a periodic flushing operation to distinguish it from the flushing operation performed as a maintenance operation immediately after releasing capping before printing starts and immediately before capping after printing ends. Note that the liquid ejection head 10 of this embodiment is always positioned vertically above, on the -Z direction side of the transport path along which the paper P is transported. For this reason, the periodic flushing operation in this embodiment is performed on the cap 52 placed at the opposing position when there is no paper P vertically below, on the +Z direction side of the nozzle surface 11 of the liquid ejection head 10, and at a timing when the time elapsed since the previous flushing operation exceeds a preset time.

[0051] For example, when printing images or characters on paper P in a printing mode without unused nozzle groups that uses black ink, cyan ink, magenta ink, and yellow ink, the control unit 90 controls the drive circuit 15 so that, in the printing operation that prints in the printing mode without unused nozzle groups, the control unit 90 supplies an ejection pulse Pep to the drive elements E of the used ejection unit groups, that is, the black ink ejection unit group, the cyan ink ejection unit group, the magenta ink ejection unit group, and the yellow ink ejection unit group, during the period when ink is ejected, and supplies an in-print micro-vibration pulse Pbp during the period when ink is not ejected.

[0052] In this embodiment, the print mode that the control unit 90 determines to be the first color print mode based on the conditions of print job J corresponds to a print mode without unused nozzle groups that uses color inks including cyan ink, magenta ink, and yellow ink, and black ink. For example, when the print mode is color and the image quality mode is low image quality, or when the print mode is color and the type of paper P is plain paper, among the conditions of print job J, the control unit 90 determines that the print mode for printing to be performed is the first color print mode. At this time, the used ejection unit groups are the color ink ejection unit group including the cyan ink ejection unit group, the magenta ink ejection unit group, and the yellow ink ejection unit group, and the black ink ejection unit group.

[0053] By operating the drive element E by supplying an ejection pulse Pep, ink is ejected from the nozzle N corresponding to the drive element E. Furthermore, by operating the drive element E by supplying an in-print micro-vibration pulse Pbp, micro-vibrations are generated in the ink in the nozzle N corresponding to the drive element E. In this way, when printing on paper P, micro-vibrations are generated in the ink in the nozzle N of the used ejection unit group, and the ink in the nozzle N is appropriately agitated, thereby reducing localized thickening in the vicinity of the nozzle N.

[0054] On the other hand, when printing on paper P, if the ink in the nozzles N of the non-used ejection unit group is vibrated slightly, the ink in the nozzles N and pressure chambers C is not ejected from the nozzles N, and therefore the thickened ink near the nozzles N may spread over a wider range of the nozzles N and pressure chambers C than when the ink in the nozzles N of the used ejection unit group is vibrated slightly. Also, in this case, the volume of ink to be ejected from each nozzle N in the non-used nozzle group flushing operation aimed at maintaining the state of the ink in the nozzles N and pressure chambers C of the non-used ejection unit group may be greater than the volume of ink to be ejected from each nozzle N in the used nozzle group flushing operation aimed at maintaining the state of the ink in the nozzles N and pressure chambers C of the used ejection unit group.

[0055] For this reason, when printing images or characters on paper P, for example, if the printing is in a printing mode with unused nozzle groups that does not use any of the black, cyan, magenta, or yellow inks, the control unit 90 controls the drive circuit 15 so that, during the in-print period of the printing operation in which printing is performed in the printing mode with unused nozzle groups, an ejection pulse Pep is supplied to the drive elements E of the used ejection group during the period when ink is ejected, and an in-print micro-vibration pulse Pbp is supplied during the period when ink is not ejected, and a micro-vibration pulse Pb is not supplied to the drive elements E of the unused ejection group even during the period when ink is not ejected.

[0056] In addition, the control unit 90 controls the drive circuit 15 so that during the non-printing period of the printing operation in which printing is performed in a printing mode with a non-used nozzle group, a non-printing micro-vibration pulse Pbm is supplied to the drive elements E of the used ejection group, and a micro-vibration pulse Pb is not supplied to the drive elements E of the non-used ejection group.

[0057] As a result, micro-vibrations are not performed in the unused ejection unit group during printing on the paper P, and therefore it is possible to suppress diffusion of thickened ink near the nozzle N toward the pressure chamber C. Also, as a result, during printing operations, the degree to which thickened ink near the nozzle N of the unused ejection unit group diffuses into the nozzle N and the pressure chamber C is smaller than the degree to which thickened ink near the nozzle N of the used ejection unit group diffuses into the nozzle N and the pressure chamber C.

[0058] For this reason, the control unit 90 makes the volume of ink ejected from each nozzle N in the non-used nozzle group flushing operation executed during the printing operation smaller than the volume of ink ejected from each nozzle N in the used nozzle group flushing operation executed during the printing operation. This makes it possible to reduce the amount of ink ejected in the non-used ejection unit groups that are not used during printing on the paper P, in order to maintain the state of the ink.

[0059] The control unit 90 reduces the volume of ink ejected from each nozzle N in one non-used nozzle group flushing operation in a printing operation to be less than the volume of ink ejected from each nozzle N in one used nozzle group flushing operation, thereby reducing the volume of ink ejected from each nozzle N in a non-used nozzle group flushing operation performed in a printing operation to be less than the volume of ink ejected from each nozzle N in a used nozzle group flushing operation performed. In this case, the control unit 90 reduces the number of times ink droplets are ejected from each nozzle N in one non-used nozzle group flushing operation to be less than the number of times ink droplets are ejected from each nozzle in one used nozzle group flushing operation. Alternatively, the control unit 90 may reduce the volume of ink droplets ejected from each nozzle N in one non-used nozzle group flushing operation to be less than the volume of ink droplets ejected from each nozzle N in one used nozzle group flushing operation.

[0060] In addition, the control unit 90 makes the time interval for performing a non-used nozzle group flushing operation longer than the time interval for performing a used nozzle group flushing operation during a printing operation, thereby making the volume of ink ejected from each nozzle N in the non-used nozzle group flushing operation performed during a printing operation less than the volume of ink ejected from each nozzle N in the used nozzle group flushing operation performed.

[0061] In a printing operation, when the volume of ink ejected from each nozzle N in a single non-used nozzle group flushing operation is made smaller than the volume of ink ejected from each nozzle N in a single used nozzle group flushing operation, the time interval for performing the non-used nozzle group flushing operation in the printing operation may be the same as the time interval for performing the used nozzle group flushing operation, or may be different from the time interval for performing the used nozzle group flushing operation, and may, for example, be shorter than the time interval for performing the used nozzle group flushing operation.

[0062] Furthermore, in a printing operation, by making the time interval for performing a non-used nozzle group flushing operation longer than the time interval for performing a used nozzle group flushing operation, when the volume of ink ejected from each nozzle N in a non-used nozzle group flushing operation performed in a printing operation is made smaller than the volume of ink ejected from each nozzle N in a used nozzle group flushing operation performed, the volume of ink ejected from each nozzle N in one non-used nozzle group flushing operation in a printing operation may be the same as the volume of ink ejected from each nozzle in one used nozzle group flushing operation, or may be different from the volume of ink ejected from each nozzle in one used nozzle group flushing operation, and may, for example, be greater than the volume of ink ejected from each nozzle in one used nozzle group flushing operation.

[0063] In this embodiment, the print mode that the control unit 90 determines to be the monochrome print mode based on the conditions of print job J corresponds to a print mode with unused nozzle groups that uses black ink and does not use color inks including cyan ink, magenta ink, and yellow ink. For example, when the print mode is monochrome among the conditions of print job J, the control unit 90 determines that the print mode for printing to be performed is the monochrome print mode. At this time, the used ejection unit group is the black ink ejection unit group, and the unused ejection unit group is the color ink ejection unit group including the cyan ink ejection unit group, the magenta ink ejection unit group, and the yellow ink ejection unit group.

[0064] Furthermore, in this embodiment, the print mode that the control unit 90 determines to be the second color print mode from the conditions of print job J corresponds to a print mode with unused nozzle groups that uses color inks including cyan ink, magenta ink, and yellow ink, and does not use black ink. For example, when the print mode is color and the image quality mode is high quality, or when the print mode is color and the type of paper P is photo paper, the control unit 90 determines that the print mode for printing to be performed is the second color print mode. At this time, the used ejection unit group is a color ink ejection unit group including a cyan ink ejection unit group, a magenta ink ejection unit group, and a yellow ink ejection unit group, and the unused ejection unit group is a black ink ejection unit group.

[0065] 6, a process flow when the control unit 90 executes a printing operation based on a print job J in this embodiment will be described. In this embodiment, the process flow when the control unit 90 executes a printing operation based on a print job J corresponds to a control method of the liquid ejection device 100.

[0066] When the user inputs the various conditions of the print job J described above by operating the external device 200 or the operation unit 82, the control unit 90 checks the various conditions of the print job J that have been input in step S11.

[0067] In step S11, when the various conditions of the input print job J are confirmed, the control unit 90 advances the process to step S12.

[0068] In step S12, the control unit 90 checks whether or not there is a nozzle group that is not used in printing on paper P in printing based on the print job J. In this embodiment, the control unit 90 judges whether or not there is a nozzle group that is not used in printing on paper P from the print mode (color / monochrome), the type of paper P (photo paper / plain paper), and the image quality mode (high image quality / normal image quality / low image quality) among various conditions of the print job J. If the control unit 90 cannot judge whether or not there is a nozzle group that is not used in printing on paper P only from the various conditions of the print job J, it judges that there is no nozzle group that is not used in printing on paper P. If there is a nozzle group that is not used in printing on paper P, step S12 becomes YES. The control unit 90 transitions the process to step S13.

[0069] The control unit 90 determines that printing based on the print job J is in a print mode with an unused nozzle group, and in step S13, sets the supply specifications of the micro-vibration pulse Pb to the drive elements E of each ejection group to the print mode specifications with an unused nozzle group. In this embodiment, during the in-print period of the printing operation in which printing is performed in the print mode with an unused nozzle group, the in-print micro-vibration pulse Pbp is supplied to the drive elements E of the used ejection group during the period in which ink is not ejected, and the micro-vibration pulse Pb is not supplied to the drive elements E of the unused ejection group even during the period in which ink is not ejected.

[0070] In addition, in this embodiment, in a non-printing period of a printing operation in which printing is performed in a printing mode with a non-used nozzle group, a non-printing micro-vibration pulse Pbm is supplied to the driving elements E of the used ejection part groups, and a micro-vibration pulse Pb is not supplied to the driving elements E of the non-used ejection part groups. In step S13, when the supply specifications of the micro-vibration pulse Pb to the driving elements E of each ejection part group are set to the printing mode specifications with a non-used nozzle group, the control unit 90 proceeds to step S15.

[0071] In step S12, if there is no nozzle group that is not used in printing on paper P in printing based on print job J, step S12 becomes NO. The control unit 90 transitions the process to step S14.

[0072] The control unit 90 determines that printing based on the print job J is in a print mode without unused nozzle groups, and in step S14, sets the supply specifications of the micro-vibration pulse Pb to the drive elements E of each ejection group to the print mode specifications without unused nozzle groups. In this embodiment, during the in-print period of the printing operation in which printing is performed in the print mode without unused nozzle groups, the in-print micro-vibration pulse Pbp is supplied to the drive elements E of the used ejection groups, i.e., all ejection groups, during the period in which ink is not ejected.

[0073] In this embodiment, in the non-printing period of the printing operation in which printing is performed in the printing mode without non-used nozzle groups, the non-printing micro-vibration pulse Pbm is supplied to the driving elements E of the used ejection part groups, i.e., all ejection part groups. In step S14, when the supply specification of the micro-vibration pulse Pb to the driving elements E of each ejection part group is set to the printing mode specification without non-used nozzle groups, the control unit 90 proceeds to step S15.

[0074] In step S15, the control unit 90 executes a printing operation to print on the paper P based on the input print job J. When the control unit 90 starts the printing operation, it moves the cap 52 from the capping position to the separated position, thereby putting the liquid ejection head 10 in a capped standby state to a state where printing can be started. Then, the control unit 90 causes the transport unit 30 to transport the paper P to a printable position, and causes the drive circuit 15 to supply ejection pulses Pep to the drive elements E of the used ejection unit group, thereby ejecting ink from the nozzles N of the liquid ejection head 10 onto the paper P at the printable position, thereby performing printing. When the printing based on the print job J is completed, the control unit 90 moves the cap 52 from the separated position to the capping position, puts the liquid ejection head 10 in a capped standby state, and ends the printing operation.

[0075] Furthermore, the control unit 90 controls the drive circuit 15 during the printing operation to perform the micro-vibration operation. In this case, when the printing performed based on the print job J is in a print mode with non-used nozzle groups, the control unit 90 supplies the micro-vibration pulse Pb to the drive elements E of each ejection unit group during the in-print period and the out-of-print period of the printing operation in a print mode specification with non-used nozzle groups. Furthermore, when the printing performed based on the print job J is in a print mode without non-used nozzle groups, the control unit 90 supplies the micro-vibration pulse Pb to the drive elements E of each ejection unit group during the in-print period and the out-of-print period of the printing operation in a print mode specification without non-used nozzle groups.

[0076] Furthermore, the control unit 90 executes a flushing operation by controlling the drive circuit 15 during printing. The flushing operation includes a flushing operation that is performed as necessary either immediately after releasing capping or immediately before capping after printing is completed, and a regular flushing operation that is performed every time a preset time has elapsed. Furthermore, the regular flushing operation includes an active nozzle group flushing operation and an unused nozzle group flushing operation.

[0077] The control unit 90 makes the volume of ink ejected from each nozzle N in a non-used nozzle group flushing operation performed during a printing operation smaller than the volume of ink ejected from each nozzle N in a used nozzle group flushing operation performed during a printing operation. In this case, the control unit 90 makes the volume of ink ejected from each nozzle N in one non-used nozzle group flushing operation during a printing operation smaller than the volume of ink ejected from each nozzle N in one used nozzle group flushing operation. Furthermore, the control unit 90 makes the time interval for performing a non-used nozzle group flushing operation longer than the time interval for performing a used nozzle group flushing operation during a printing operation.

[0078] After executing the process of step S15, the control unit 90 ends the process for executing the printing operation based on the print job J.

[0079] As described above, the liquid ejection device 100 according to the first embodiment and the control method for the liquid ejection device 100 can provide the following advantages.

[0080] The liquid ejection device 100 includes a plurality of ejection units 13 each having a nozzle N capable of ejecting ink, a pressure chamber C communicating with the nozzle N, and a drive element E for generating a pressure fluctuation in the ink in the pressure chamber C by being supplied with a drive pulse P; a drive circuit 15 capable of supplying a drive pulse P to the drive element E of the ejection unit 13, the drive pulse P including an ejection pulse Pep for ejecting ink from the nozzle N and an in-printing micro-vibration pulse Pbp for vibrating an air-liquid interface in the nozzle N when ink is not ejected from the nozzle N; and a control unit 90. The control unit 90 controls the drive circuit 15 based on a print job J for executing a printing operation for printing on paper P, thereby ejecting ink from the nozzle N to execute the printing operation. The plurality of ejection units 13 form a plurality of ejection unit groups each having a plurality of nozzles N constituting a nozzle row 12 capable of ejecting any one of a plurality of types of ink, and in the printing on paper P, the ejection unit group capable of ejecting the ink to be used is referred to as a used ejection unit group, and the ejection unit group capable of ejecting the ink not to be used is referred to as a used ejection unit group. When the nozzle group is an unused nozzle group, if the printing is in a printing mode without an unused nozzle group using the multiple types of ink, the control unit 90 controls the drive circuit 15 to supply an ejection pulse Pep to the drive elements E of the used ejection unit group during a period when ink is ejected, and to supply an in-print micro-vibration pulse Pbp during a period when ink is not ejected, in the printing operation to perform the printing in the printing mode without an unused nozzle group; when the printing is in a printing mode with an unused nozzle group not using any of the multiple types of ink, the control unit 90 controls the drive circuit 15 to supply an ejection pulse Pep to the drive elements E of the used ejection unit group during a period when ink is ejected, and to supply an in-print micro-vibration pulse Pbp during a period when ink is not ejected, in the printing operation to perform the printing in the printing mode with an unused nozzle group,

[0081] According to this, in the non-use ejection part group that is not used in printing on the paper P, micro-vibrations are not performed during the printing operation, so that thickened ink near the nozzles N can be prevented from diffusing toward the pressure chambers C side.

[0082] In the liquid ejection device 100, the control unit 90 executes an in-use nozzle group flushing operation that causes ink to be ejected from the nozzles N of the in-use ejection unit group, and an in-use nozzle group flushing operation that causes ink to be ejected from the nozzles N of the in-use ejection unit group. This makes it possible to maintain the state of the ink by performing the flushing operation.

[0083] In the liquid ejection device 100, the volume of ink ejected from the nozzles N in one unused nozzle group flushing operation during a printing operation is smaller than the volume of ink ejected from the nozzles N in one used nozzle group flushing operation. This makes it possible to reduce the amount of ink ejected from the nozzles N of the unused ejection group that are not used during the printing operation.

[0084] In the liquid ejection device 100, the time interval for performing the non-used nozzle group flushing operation during the printing operation is longer than the time interval for performing the used nozzle group flushing operation. This makes it possible to reduce the amount of ink discharged from the nozzles N of the non-used ejection unit group that are not used during the printing operation.

[0085] In the liquid ejection device 100, the multiple types of ink are black ink and color inks of different colors from the black ink, the multiple ejection unit groups are a black ink ejection unit group having multiple nozzles N constituting a black ink nozzle group capable of ejecting black ink, and a color ink ejection unit group having multiple nozzles N constituting a color ink nozzle group capable of ejecting color ink, the printing mode without unused nozzle groups is a first color printing mode using color inks and black ink, the used ejection unit groups are the color ink ejection unit groups and the black ink ejection unit groups, the printing mode with unused nozzle groups is a monochrome printing mode using black ink but not color inks, the used ejection unit group is the black ink ejection unit group, and the unused ejection unit group is the color ink ejection unit group. According to this, in printing in the monochrome printing mode using black ink but not color inks, the unused color ink ejection unit groups do not perform micro-vibration during printing operation, so that it is possible to suppress the thickened color ink near the nozzles N from diffusing to the pressure chamber C side.

[0086] In the liquid ejection device 100, the multiple types of ink are black ink and color inks that are different in color from the black ink, the multiple ejection unit groups are a black ink ejection unit group having multiple nozzles N constituting a black ink nozzle group capable of ejecting black ink, and a color ink ejection unit group having multiple nozzles N constituting a color ink nozzle group capable of ejecting color ink, the printing mode without unused nozzle groups is a first color printing mode that uses color inks and black ink, the used ejection unit groups are the color ink ejection unit groups and the black ink ejection unit group, the printing mode with unused nozzle groups is a second color printing mode that uses color inks and does not use black ink, the used ejection unit groups are the color ink ejection unit groups, and the unused ejection unit group is the black ink ejection unit group. According to this, in printing in the second color printing mode that uses color inks and does not use black ink, the unused black ink ejection unit group does not vibrate slightly during the printing operation, so that it is possible to suppress the thickened black ink near the nozzles N from diffusing to the pressure chamber C side.

[0087] The control method for the liquid ejection device 100 includes a plurality of ejection units 13 each having a nozzle N capable of ejecting ink, a pressure chamber C communicating with the nozzle N, and a drive element E for generating a pressure fluctuation in the ink in the pressure chamber C by being supplied with a drive pulse P, the plurality of ejection units 13 forming a plurality of ejection unit groups each having a plurality of nozzles N constituting a nozzle row 12 capable of ejecting any one of a plurality of types of ink, and a drive pulse P including an ejection pulse Pep for ejecting ink from the nozzle N and an in-printing micro-vibration pulse Pbp for vibrating an air-liquid interface in the nozzle N when ink is not ejected from the nozzle N, to the drive element E, and the control method for the liquid ejection device 100 executes a printing operation for printing on paper P, the control method comprising the steps of: in the printing on paper P, referring to the ejection unit group capable of ejecting the ink to be used as a used ejection unit group, and referring to the ejection unit group capable of ejecting the ink not to be used as a non-used ejection unit group, When the printing is in a printing mode without an unused nozzle group using the multiple types of ink, in the printing operation performing the printing in the printing mode without an unused nozzle group, an ejection pulse Pep is supplied to the drive elements E of the used ejection unit group during a period when ink is ejected, and an in-print micro-vibration pulse Pbp is supplied during a period when ink is not ejected, and when the printing is in a printing mode with an unused nozzle group not using any of the multiple types of ink, in the printing operation performing the printing in the printing mode with an unused nozzle group, an ejection pulse Pep is supplied to the drive elements E of the used ejection unit group during a period when ink is ejected, and an in-print micro-vibration pulse Pbp is supplied during a period when ink is not ejected, and a micro-vibration pulse Pb is not supplied to the drive elements E of the unused ejection unit group even in a period when ink is not ejected.

[0088] According to this, in the non-use ejection part group that is not used in printing on the paper P, micro-vibrations are not performed during the printing operation, so that thickened ink near the nozzles N can be prevented from diffusing toward the pressure chambers C side.

[0089] The control method for the liquid ejection device 100 executes an active nozzle group flushing operation for ejecting ink from the nozzles N of the active ejection section group, and an active nozzle group flushing operation for ejecting ink from the nozzles N of the active ejection section group. According to this, the state of the ink can be maintained by performing the flushing operation.

[0090] In the control method for the liquid ejection device 100, the volume of ink ejected from the nozzles N in one unused nozzle group flushing operation during a printing operation is smaller than the volume of ink ejected from the nozzles N in one used nozzle group flushing operation. This makes it possible to reduce the amount of ink ejected from the nozzles N of the unused ejection section group that are not used during the printing operation.

[0091] In the control method for the liquid ejection device 100, the time interval for performing the non-used nozzle group flushing operation during the printing operation is longer than the time interval for performing the used nozzle group flushing operation. This makes it possible to reduce the amount of ink discharged from the nozzles N of the unused ejection section group.

[0092] In the control method for the liquid ejection device 100, the multiple types of ink are black ink and color inks that are different in color from the black ink, the multiple ejection unit groups are a black ink ejection unit group having multiple nozzles N constituting a black ink nozzle group capable of ejecting black ink, and a color ink ejection unit group having multiple nozzles N constituting a color ink nozzle group capable of ejecting color ink, the printing mode without unused nozzle groups is a first color printing mode that uses color inks and black ink, the used ejection unit groups are the color ink ejection unit groups and the black ink ejection unit group, the printing mode with unused nozzle groups is a monochrome printing mode that does not use color inks and uses black ink, the used ejection unit group is the black ink ejection unit group, and the unused ejection unit group is the color ink ejection unit group. According to this, in printing in the monochrome printing mode that does not use color inks and uses black ink, the unused color ink ejection unit groups do not perform micro-vibration during the printing operation, so that it is possible to suppress the thickened color ink near the nozzles N from diffusing to the pressure chamber C side.

[0093] In the control method for the liquid ejection device 100, the multiple types of ink are black ink and color inks that are different in color from the black ink, the multiple ejection unit groups are a black ink ejection unit group having multiple nozzles N constituting a black ink nozzle group capable of ejecting black ink, and a color ink ejection unit group having multiple nozzles N constituting a color ink nozzle group capable of ejecting color ink, the printing mode without unused nozzle groups is a first color printing mode that uses color inks and black ink, the used ejection unit groups are the color ink ejection unit groups and the black ink ejection unit group, the printing mode with unused nozzle groups is a second color printing mode that uses color inks and does not use black ink, the used ejection unit groups are the color ink ejection unit groups, and the unused ejection unit group is the black ink ejection unit group. According to this, in printing in the second color printing mode that uses color inks and does not use black ink, the unused black ink ejection unit group does not vibrate slightly during the printing operation, so that it is possible to suppress the thickened black ink near the nozzles N from diffusing to the pressure chamber C side.

[0094] The liquid ejection device 100 according to the above embodiment of the present invention is basically configured as described above, but it is of course possible to modify or omit parts of the configuration without departing from the scope of the present invention. Furthermore, the above embodiment and other embodiments described below can be combined with each other within the scope of technical compatibility. Other embodiments will be described below.

[0095] In the above embodiment, the color inks different from the black ink ejected from the nozzles N by the liquid ejection head 10 may be more than three types. For example, the color inks different from the black ink may be five types: cyan ink, magenta ink, yellow ink, red ink, and green ink. In this case, the liquid ejection head 10 may have nozzle rows 12a, 12b, 12c, 12d, 12e, and 12f.

[0096] In the above embodiment, an example of the nozzle group of the liquid ejection head 10, which is a line head, does not have to be the nozzle row 12 in which a plurality of nozzles N are arranged at equal intervals in a straight line along the X-axis direction. For example, the nozzle group of the liquid ejection head 10 may be a nozzle group configured by arranging a plurality of nozzle rows in a staggered manner, each of which is formed by arranging a plurality of nozzles N ejecting ink of the same color in a line in the X-axis direction. Also, for example, the nozzle group of the liquid ejection head 10 may be a nozzle group configured by arranging a plurality of nozzle rows in the X-axis direction, each of which is formed by arranging a plurality of nozzles N ejecting ink of the same color in a line in a direction intersecting the X-axis direction.

[0097] In the above embodiment, an example of the nozzle group of the liquid ejection head 10, which is a line head, does not have to be the nozzle row 12 in which a plurality of nozzles N are arranged at equal intervals in a straight line along the X-axis direction. For example, the plurality of nozzle groups of the liquid ejection head 10 may be a nozzle section Hn provided in an area of ​​the nozzle surface 11 corresponding to a paper Pn whose paper size is smaller than that of the paper Pw, and a nozzle section Hw provided in an area adjacent to the nozzle section Hn on the -X direction side. Furthermore, when, among the conditions of the print job J, the size of the paper P is Pn and the transport direction of the paper P is vertical, the control section 90 determines that the printing to be performed is a print mode with non-used nozzle groups. At this time, the used ejection section group is the nozzle section Hn, and the non-used ejection section group is the nozzle section Hw.

[0098] In the above embodiment, the timing for performing the regular flushing operation does not have to be a timing when there is no paper P vertically below the nozzle surface 11 of the liquid ejection head 10 on the +Z direction side and when the time elapsed since the previous flushing operation does not exceed a preset time. For example, when the time elapsed since the previous flushing operation reaches a preset time, the control unit 90 may move the cap 52 to the opposing position and perform the flushing operation even if there is paper P vertically below the nozzle surface 11 of the liquid ejection head 10. Alternatively, the control unit 90 may perform the flushing operation for every preset number of printed sheets of paper P, provided that the time elapsed since the previous flushing operation does not exceed a preset time.

[0099] In the above embodiment, the control unit 90 may change the method of making the volume of ink ejected from each nozzle N in a non-used nozzle group flushing operation performed in a printing operation less than the volume of ink ejected from each nozzle N in a used nozzle group flushing operation performed, based on various conditions instructed in the print job J. For example, when it is determined that the time required for the printing operation is shorter than a preset time from various conditions instructed in the print job J, the control unit 90 may make the time interval for performing a non-used nozzle group flushing operation in a printing operation longer than the time interval for performing a used nozzle group flushing operation, and when it is determined that the time required for the printing operation is longer than the preset time, the control unit 90 may make the volume of ink ejected from each nozzle N in one non-used nozzle group flushing operation less than the volume of ink ejected from each nozzle N in one used nozzle group flushing operation, thereby making the volume of ink ejected from each nozzle N in a non-used nozzle group flushing operation performed in a printing operation less than the volume of ink ejected from each nozzle N in a used nozzle group flushing operation performed.

[0100] In the above embodiment, the control unit 90 may change the method of making the volume of ink ejected from each nozzle N in a non-used nozzle group flushing operation performed in a printing operation less than the volume of ink ejected from each nozzle N in a used nozzle group flushing operation performed, based on various conditions instructed in the print job J. For example, when it is determined that the time required for the printing operation is shorter than a preset time from various conditions instructed in the print job J, the control unit 90 may make the time interval for performing a non-used nozzle group flushing operation in a printing operation longer than the time interval for performing a used nozzle group flushing operation, and when it is determined that the time required for the printing operation is longer than the preset time, the control unit 90 may make the volume of ink ejected from each nozzle N in one non-used nozzle group flushing operation less than the volume of ink ejected from each nozzle in one used nozzle group flushing operation, thereby making the volume of ink ejected from each nozzle N in a non-used nozzle group flushing operation performed in a printing operation less than the volume of ink ejected from each nozzle N in a used nozzle group flushing operation performed.

[0101] In the above embodiment, the control unit 90 may not supply the non-printing vibration pulse Pbm to the driving element E of the used ejection unit group during the non-printing period of the printing operation in which printing is performed in the printing mode with the non-used nozzle group. For example, the control unit 90 may not supply the non-printing vibration pulse Pbm to the driving element E of the used ejection unit group during the pre-printing period of the printing operation in which printing is performed in the printing mode with the non-used nozzle group. Alternatively, when the control unit 90 can determine that the time required for the printing operation is shorter than a preset time from various conditions specified in the print job J, it may not supply the non-printing vibration pulse Pbm to the driving element E of the used ejection unit group during the non-printing period of the printing operation in which printing is performed in the printing mode with the non-used nozzle group.

[0102] In the above embodiment, the control unit 90 may supply the non-printing vibration pulse Pbm to the drive element E of the non-used ejection unit group in a non-printing period other than the pre-printing period in the printing operation in which printing is performed in the printing mode with the non-used nozzle group. For example, when the control unit 90 can determine that the time required for the printing operation is longer than a preset time from various conditions specified in the print job J, the control unit 90 may not supply the non-printing vibration pulse Pbm to the drive element E of the non-used ejection unit group until the preset time in the non-printing period other than the pre-printing period in the printing operation in which printing is performed in the printing mode with the non-used nozzle group, and may supply the non-printing vibration pulse Pbm after the preset time has elapsed.

[0103] In the above embodiment, the control unit 90 may perform a micro-vibration operation in a standby state in which the liquid ejection head 10 is capped after completing a printing operation. For example, the control unit 90 may supply a non-printing micro-vibration pulse Pbm to the driving elements E of the non-used ejection unit group in the printing operation performed immediately before in a standby state in which the liquid ejection head 10 is capped after performing a printing operation longer than a preset time. Alternatively, the control unit 90 may supply a non-printing micro-vibration pulse Pbm to the driving elements E of the non-used ejection unit group and the used ejection unit group in the printing operation performed immediately before in a standby state in which the liquid ejection head 10 is capped after performing a printing operation longer than a preset time.

[0104] In the above embodiment, the liquid ejection head 10 may not be a line head. For example, as shown in FIG. 7, the nozzle rows 12a, 12b, 12c, and 12d of the liquid ejection head 10 may be arranged along the Y-axis direction, and the nozzle rows 12a, 12b, 12c, and 12d may be arranged at intervals in the X-axis direction. Then, the liquid ejection head 10 mounted on the carriage CR may eject ink onto the paper P while moving in the X-axis direction, thereby executing a printing operation to perform printing. In this case, the flushing operation is executed at a position where the nozzle surface 11 of the liquid ejection head 10 faces either the cap 52 located in the +X direction with respect to the paper P, or the flushing receiver FLR located in the -X direction with respect to the paper P. In this case, the control unit 90 may execute the regular flushing operation at a timing when the liquid ejection head 10 is moving in the X-axis direction during the printing operation, the nozzle surface 11 faces either the cap 52 or the flushing receiver FLR, and the time elapsed since the previous flushing operation does not exceed a preset time. [Explanation of symbols]

[0105] 10...liquid ejection head, 11...nozzle surface, 12, 12a, 12b, 12c, 12d...nozzle row, 13...ejection section, 15...driving circuit, 20...liquid supply section, 30...transport section, 50...maintenance section, 51...maintenance unit holding section, 52...cap, 53...wiper, 54...waste liquid tube, 55...suction pump, 56...waste liquid collection section, 80...input / output section, 81...display section, 82...operation section, 90...control section, 91...control device, 92...storage device, 100...liquid ejection device, 200...external device.

Claims

1. a plurality of ejection units each having a nozzle capable of ejecting liquid, a pressure chamber communicating with the nozzle, and a drive element which generates a pressure fluctuation in the liquid in the pressure chamber by being supplied with a drive pulse; a drive circuit capable of supplying drive pulses to the drive element of the ejection unit, the drive pulse including an ejection pulse for ejecting the liquid from the nozzle and a micro-vibration pulse for vibrating an air-liquid interface in the nozzle when the liquid is not ejected from the nozzle; a control unit that controls the drive circuit based on a print job for executing a printing operation for printing on a medium, thereby causing the liquid to be ejected from the nozzles to execute the printing operation; Equipped with the printing operation includes an in-printing period during which the printing is performed on the medium, and a non-printing period other than the in-printing period, the plurality of ejection units form a plurality of ejection unit groups each having a plurality of nozzles constituting a nozzle group capable of ejecting any one of the plurality of types of liquid; In the printing on the medium, the ejection part group capable of ejecting the liquid to be used is defined as an used ejection part group, and the ejection part group capable of ejecting the liquid not to be used is defined as an unused ejection part group, the control unit determines, based on the print job, whether the printing is in a printing mode without an unused nozzle group in which the plurality of types of the liquids are used, or in a printing mode with an unused nozzle group in which any of the plurality of types of the liquids is not used, when the control unit determines that the printing is in a printing mode without unused nozzle groups using the multiple types of liquids, the control unit controls the drive circuit so that, during the in-print period of the printing operation in which the printing is performed in the printing mode without unused nozzle groups, the control unit supplies the ejection pulse to the drive elements of the active ejection unit group for each unit period in which the liquid is ejected, and supplies the micro-vibration pulse to the drive elements of the active ejection unit group for each unit period in which the liquid is not ejected, when the control unit determines that the printing is in a printing mode with unused nozzle groups in which any of the plurality of types of liquids is not used, the control unit controls the drive circuit so that, during the in-print period of the printing operation in which the printing is performed in the printing mode with unused nozzle groups, the control unit supplies, for each unit period, the ejection pulse to the drive elements of the used ejection unit groups during a unit period in which the liquid is ejected and supplies the micro-vibration pulse to the drive elements of the unused ejection unit groups during a unit period in which the liquid is not ejected, and does not supply the micro-vibration pulse to the drive elements of the unused ejection unit groups even during a unit period in which the liquid is not ejected. A liquid ejection device comprising:

2. the control unit executes an in-use nozzle group flushing operation for causing the nozzles of the in-use ejection unit group to eject the liquid, and an unused nozzle group flushing operation for causing the nozzles of the unused ejection unit group to eject the liquid. The liquid ejection device according to claim 1 .

3. In the printing operation, a volume of the liquid ejected from the nozzles in one non-used nozzle group flushing operation is smaller than a volume of the liquid ejected from the nozzles in one used nozzle group flushing operation. The liquid ejection device according to claim 2 .

4. In the printing operation, a time interval for performing the non-used nozzle group flushing operation is longer than a time interval for performing the used nozzle group flushing operation.

4. The liquid ejection apparatus according to claim 2, wherein the liquid ejection apparatus is a liquid ejection apparatus.

5. the plurality of types of liquids are black ink and color inks that are different in color from the black ink, the plurality of ejection unit groups are a black ink ejection unit group having a plurality of the nozzles constituting a black ink nozzle group capable of ejecting the black ink, and a color ink ejection unit group having a plurality of the nozzles constituting a color ink nozzle group capable of ejecting the color inks, the printing mode without unused nozzle groups is a first color printing mode that uses the color inks and the black ink, and the used ejection unit groups are the color ink ejection unit group and the black ink ejection unit group, the printing mode with unused nozzle group is a monochrome printing mode in which the color inks are not used and the black ink is used, and the used ejection unit group is the black ink ejection unit group; the non-use ejection unit group is the color ink ejection unit group, The liquid ejection device according to any one of claims 1 to 4.

6. the plurality of types of liquids are black ink and color inks that are different in color from the black ink, the plurality of ejection unit groups are a black ink ejection unit group having a plurality of the nozzles constituting a black ink nozzle group capable of ejecting the black ink, and a color ink ejection unit group having a plurality of the nozzles constituting a color ink nozzle group capable of ejecting the color inks, the printing mode without unused nozzle groups is a first color printing mode that uses the color inks and the black ink, and the used ejection unit groups are the color ink ejection unit group and the black ink ejection unit group, the printing mode with unused nozzle group is a second color printing mode in which the color inks are used and the black ink is not used, the used ejection unit group is the color ink ejection unit group, and the unused ejection unit group is the black ink ejection unit group; The liquid ejection device according to any one of claims 1 to 4.

7. a plurality of ejection units each having a nozzle capable of ejecting liquid, a pressure chamber communicating with the nozzle, and a drive element that generates a pressure fluctuation in the liquid in the pressure chamber by being supplied with a drive pulse; the plurality of ejection units form a plurality of ejection unit groups each having a plurality of nozzles constituting a nozzle group capable of ejecting any one of the plurality of types of liquid; A method for controlling a liquid ejection device that executes a printing operation for printing on a medium by supplying a driving pulse to the driving element, the driving pulse including an ejection pulse for ejecting the liquid from the nozzle and a micro-vibration pulse for vibrating an air-liquid interface in the nozzle when the liquid is not ejected from the nozzle, the method comprising: the printing operation includes an in-printing period during which the printing is performed on the medium, and a non-printing period other than the in-printing period, In the printing on the medium, the ejection part group capable of ejecting the liquid to be used is defined as an used ejection part group, and the ejection part group capable of ejecting the liquid not to be used is defined as an unused ejection part group, determining, based on a print job for executing a printing operation for printing on a medium, whether the printing is in a printing mode without an unused nozzle group in which the plurality of types of the liquids are used, or in a printing mode with an unused nozzle group in which any of the plurality of types of the liquids is not used; when it is determined that the printing is a printing mode without unused nozzle groups using the plurality of types of liquids, during the in-print period of the printing operation in which the printing is performed in the printing mode without unused nozzle groups, the ejection pulse is supplied to the drive elements of the active ejection unit group for each unit period during which the liquid is ejected, and the micro-vibration pulse is supplied to the drive elements of the active ejection unit group for each unit period during which the liquid is not ejected, when it is determined that the printing is in a printing mode with unused nozzle groups in which any of the plurality of types of liquids is not used, during the in-print period of the printing operation in which the printing is performed in the printing mode with unused nozzle groups, the ejection pulse is supplied to the drive elements of the used ejection unit group for each unit period in which the liquid is ejected, and the micro-vibration pulse is supplied to the drive elements of the unused ejection unit group for each unit period in which the liquid is not ejected, and the micro-vibration pulse is not supplied to the drive elements of the unused ejection unit group even during the unit period in which the liquid is not ejected. A method for controlling a liquid ejection device comprising the steps of:

8. performing an in-use nozzle group flushing operation for ejecting the liquid from the nozzles of the in-use ejection unit group, and an unused nozzle group flushing operation for ejecting the liquid from the nozzles of the unused ejection unit group; The method for controlling a liquid ejection device according to claim 7 .

9. In the printing operation, a volume of the liquid ejected from the nozzles in one non-used nozzle group flushing operation is smaller than a volume of the liquid ejected from the nozzles in one used nozzle group flushing operation. The method for controlling a liquid ejection device according to claim 8 .

10. In the printing operation, a time interval for performing the non-used nozzle group flushing operation is longer than a time interval for performing the used nozzle group flushing operation.

10. The method for controlling the liquid ejection device according to claim 8 or 9.

11. the plurality of types of liquids are black ink and color inks that are different in color from the black ink, the plurality of ejection unit groups are a black ink ejection unit group having a plurality of the nozzles constituting a black ink nozzle group capable of ejecting the black ink, and a color ink ejection unit group having a plurality of the nozzles constituting a color ink nozzle group capable of ejecting the color inks, the printing mode without unused nozzle groups is a first color printing mode that uses the color inks and the black ink, and the used ejection unit groups are the color ink ejection unit group and the black ink ejection unit group, the printing mode with unused nozzle group is a monochrome printing mode in which the color inks are not used and the black ink is used, the used ejection unit group is the black ink ejection unit group, and the unused ejection unit group is the color ink ejection unit group; The method for controlling the liquid ejection device according to any one of claims 7 to 10.

12. the plurality of types of liquids are black ink and color inks that are different in color from the black ink, the plurality of ejection unit groups are a black ink ejection unit group having a plurality of the nozzles constituting a black ink nozzle group capable of ejecting the black ink, and a color ink ejection unit group having a plurality of the nozzles constituting a color ink nozzle group capable of ejecting the color inks, the printing mode without unused nozzle groups is a first color printing mode that uses the color inks and the black ink, and the used ejection unit groups are the color ink ejection unit group and the black ink ejection unit group, the printing mode with unused nozzle group is a second color printing mode in which the color inks are used and the black ink is not used, the used ejection unit group is the color ink ejection unit group, and the unused ejection unit group is the black ink ejection unit group; The method for controlling the liquid ejection device according to any one of claims 7 to 10.

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