Liquid discharge device and control method for liquid discharge device

Abstract

To provide a liquid discharge device and a control method of the liquid discharge device that can suppress the impact of sedimentation on print quality while reducing a consumption amount of liquid.SOLUTION: A liquid discharge device includes: a liquid discharge head 17 that discharges liquid from multiple nozzles 32 in a discharge direction Dj intersecting the vertical direction Z to a medium 20 that is conveyed to perform printing; and a control unit 23 that controls the liquid discharge head 17. The liquid contains pigment components. The liquid discharge head 17 is equipped with a nozzle array in which the multiple nozzles 32 are arrayed. The control unit 23 performs flushing being the discharge of the liquid unrelated to printing from the multiple nozzles 32 by a discharge amount based on the difference of elevation of the multiple nozzles 32.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a liquid ejection device such as a printer, and a method for controlling the liquid ejection device. [Background technology]

[0002] For example, as disclosed in Patent Document 1, there is a liquid ejection device that is an example of a liquid ejection device that prints by ejecting ink, which is an example of a liquid, from a head, which is an example of a liquid ejection head. The head has a nozzle forming surface. A nozzle row in which a plurality of nozzles are arranged is provided on the nozzle forming surface. The head is installed so that the nozzle forming surface is inclined with respect to the horizontal plane. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-88308 A Summary of the Invention [Problem to be solved by the invention]

[0004] Liquids that contain pigment components can become uneven in concentration due to settling of the pigment components. When settling occurs in a liquid ejection head with height differences in the nozzle rows, the nozzles at higher positions eject liquid with a lower concentration, while the nozzles at lower positions eject liquid with a higher concentration. This results in unevenness in the printout. The unevenness in the printout can be reduced by flushing or the like before printing to discharge the liquid with uneven concentration. However, discharging all of the liquid with uneven concentration would consume a large amount of liquid. [Means for solving the problem]

[0005] A liquid ejection device that solves the above problem comprises a liquid ejection head that prints by ejecting liquid from multiple nozzles onto a transported medium in an ejection direction that intersects the vertical direction, and a control unit that controls the liquid ejection head, wherein the liquid contains a pigment component, and the liquid ejection head is provided with a nozzle row in which multiple nozzles are lined up, and the control unit performs flushing, which is the ejection of the liquid unrelated to the printing from the multiple nozzles in an ejection amount based on the elevation difference between the multiple nozzles.

[0006] A control method for a liquid ejection device that solves the above problem is a control method for a liquid ejection device that has a liquid ejection head that prints by ejecting liquid from a plurality of nozzles in an ejection direction that intersects the vertical direction onto a transported medium, the liquid containing a pigment component, and the liquid ejection head is provided with a nozzle row in which a plurality of the nozzles are arranged in a line, and includes performing flushing, which is the ejection of the liquid unrelated to the printing from the plurality of nozzles in an ejection amount based on the height difference between the plurality of nozzles. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a first embodiment of a liquid ejection device. [Diagram 2] FIG. 2 is a schematic diagram of a liquid ejection head. [Diagram 3] FIG. 3 is a schematic diagram of a unit head included in the liquid ejection head. [Figure 4] FIG. 4 is a partial cross-sectional view of the liquid ejection head. [Diagram 5] FIG. 5 is a schematic diagram of a second embodiment of a liquid ejection head. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [First embodiment] A first embodiment of a liquid ejection device and a method for controlling the liquid ejection device will be described below with reference to the drawings. The liquid ejection device of this embodiment is, for example, an inkjet printer that ejects ink, which is an example of a liquid, onto a medium such as paper to perform printing.

[0009] In the drawings, the liquid ejection device 11 is placed on a horizontal plane, the direction of gravity is indicated by the Z axis, and the directions along the horizontal plane are indicated by the X and Y axes. The X, Y, and Z axes are perpendicular to each other. In the following description, the direction parallel to the Y axis is also referred to as the width direction Y, and the direction parallel to the Z axis is also referred to as the vertical direction Z.

[0010] <Liquid discharge device> As shown in Fig. 1, liquid ejection device 11 may include a housing 12, a cassette 13, a feeding unit 14, a transport unit 15, a holding unit 16, a liquid ejection head 17, and a stacker 18. Liquid ejection device 11 may include a plurality of cassettes 13 and a plurality of feeding units 14. In Fig. 1, a transport path 21 along which medium 20 is transported is indicated by a dashed dotted line. Transport path 21 is a path that connects cassette 13 and stacker 18.

[0011] The liquid ejection device 11 includes a control unit 23. The control unit 23 controls various operations executed by the liquid ejection device 11. The control unit 23 controls the liquid ejection head 17. The control unit 23 may be configured as a circuit including: α: one or more processors that execute various processes according to a computer program; β: one or more dedicated hardware circuits that execute at least some of the various processes; or γ: a combination thereof. The hardware circuit is, for example, an application specific integrated circuit. The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer readable medium, includes any readable medium that can be accessed by a general-purpose or dedicated computer.

[0012] The housing 12 accommodates various components of the liquid ejection device 11 . The cassette 13 is capable of housing the medium 20. The cassette 13 is capable of being inserted into and removed from the housing 12. The cassette 13 may be capable of housing a plurality of the media 20 in a stacked state.

[0013] The feeding unit 14 feeds the media 20 contained in the cassette 13 one by one from the cassette 13 to the transport path 21. The feeding unit 14 may include a feeding roller 25 and a separating unit .

[0014] The feed roller 25 rotates while in contact with the medium 20, thereby sending the medium 20 to the transport path 21. The feed roller 25 sends the uppermost medium 20 among the media 20 stored in the cassette 13. The separation unit 26 separates the media 20 sent in a stacked state one by one. The separation unit 26 holds the second and subsequent media 20 from the top in the cassette 13.

[0015] The transport unit 15 transports the medium 20 sent by the feeding unit 14 along the transport path 21. The transport unit 15 transports the medium 20 in a transport direction Dc. The transport direction Dc is a direction along the transport path 21. The transport direction Dc is a direction from the cassette 13 toward the stacker 18. The transport unit 15 may include one or more transport rollers 28, an endless transport belt 29, and a pair of pulleys 30.

[0016] The transport rollers 28 rotate with the medium 20 sandwiched between them, thereby transporting the medium 20 along the transport path 21. The transport rollers 28 eject the printed medium 20 into the stacker 18. The stacker 18 receives the medium 20 transported by the transport unit 15.

[0017] The conveyor belt 29 is stretched around a pair of pulleys 30. The conveyor belt 29 faces the liquid ejection head 17 across the conveying path 21. The conveyor belt 29 supports a portion of the medium 20 in a flat state. The conveyor belt 29 may convey the medium 20 by rotating while adsorbing the medium 20.

[0018] The holding portion 16 holds the liquid ejection head 17 . <Liquid ejection head> As shown in FIG. 1, the liquid ejection head 17 has a nozzle surface 33 in which a plurality of nozzles 32 are open. The liquid ejection head 17 of this embodiment is a line head extending in the width direction Y. The liquid ejection head 17 ejects liquid from the plurality of nozzles 32 onto the transported medium 20 to perform printing. The liquid ejection head 17 of this embodiment ejects liquid onto the transported medium 20 in a stationary state to perform printing. The liquid ejection head 17 prints by ejecting liquid across the width direction Y onto the medium 20 supported by the transport belt 29. The liquid ejected by the liquid ejection head 17 contains a pigment component.

[0019] The liquid ejection head 17 is provided with a nozzle surface 33 tilted relative to a horizontal plane. The liquid ejection head 17 ejects liquid in an ejection direction Dj. The ejection direction Dj may be a direction perpendicular to the nozzle surface 33 and intersects with the vertical direction Z.

[0020] 2, the liquid ejection head 17 is provided with a nozzle row L. The nozzle row L is configured with a plurality of nozzles 32 lined up. The plurality of nozzles 32 that constitute one nozzle row L are lined up in a direction oblique to the transport direction Dc and the width direction Y. The liquid ejection head 17 may have a plurality of nozzle rows L. In each nozzle row L, the nozzle 32 located downstream in the transport direction Dc is located higher in the vertical direction Z than the nozzle 32 located upstream in the transport direction Dc.

[0021] The liquid ejection head 17 may include a plurality of unit heads 35. The plurality of unit heads 35 are arranged in the width direction Y. The plurality of unit heads 35 have the same configuration. Therefore, in the following explanation, one unit head 35 will be explained.

[0022] 3, the unit head 35 may have a plurality of nozzle groups 37. The unit head 35 of this embodiment has six nozzle groups 37 aligned in the width direction Y. Each nozzle group 37 of this embodiment has four nozzle rows L. In this embodiment, the nozzle rows L of the six nozzle groups 37 are also referred to as a first nozzle row L1 to a sixth nozzle row L6, respectively.

[0023] One nozzle row L is composed of a plurality of nozzles 32 that eject the same type of liquid. Each nozzle group 37 may have a plurality of first nozzles 32a to fourth nozzles 32d that eject different types of liquid. For example, the first nozzle 32a may eject cyan ink. The second nozzle 32b may eject yellow ink. The third nozzle 32c may eject magenta ink. The fourth nozzle 32d may eject black ink.

[0024] The multiple nozzles 32 that eject the same type of liquid may constitute multiple nozzle rows L. In this embodiment, the multiple nozzles 32 that eject the same type of liquid constitute a first nozzle row L1 to a sixth nozzle row L6.

[0025] The multiple nozzle rows L that eject the same type of liquid are aligned in the width direction Y. That is, the second nozzle row L2 is aligned with the first nozzle row L1 in the width direction Y and ejects the same type of liquid as the first nozzle row L1.

[0026] Among the multiple nozzle rows L that eject the same type of liquid, adjacent nozzle rows L overlap in the transport direction Dc. That is, one or more first nozzles 32a that configure the upper end portion Lu of the first nozzle row L1 and one or more first nozzles 32a that configure the lower end portion Ld of the second nozzle row L2 are provided to overlap in the transport direction Dc.

[0027] Specifically, the first distance La is shorter than the second distance Lb. The first distance La is the distance in the width direction Y from the uppermost first nozzle 32a in the first nozzle row L1 to the center C of the second nozzle row L2. The second distance Lb is the distance in the width direction Y from the lowermost first nozzle 32a in the second nozzle row L2 to the center C.

[0028] The nozzle arrays L have the same configuration. Therefore, in the following description, one nozzle array L will be described. 4, the liquid ejection head 17 may have a plurality of common liquid chambers 39 and a plurality of cavities 40. One common liquid chamber 39 is provided corresponding to one nozzle row L. The common liquid chamber 39 has an inlet 41 through which the liquid is introduced.

[0029] The common liquid chamber 39 temporarily stores the liquid introduced from the inlet 41. The multiple cavities 40 are provided to correspond respectively to the multiple nozzles 32. The cavities 40 send the liquid stored in the common liquid chamber 39 to the corresponding nozzles 32.

[0030] For example, the control unit 23 may divide the nozzles 32 constituting the nozzle row L into a plurality of blocks and set a discharge amount for each block to perform flushing. For example, the control unit 23 may divide the nozzles 32 constituting the nozzle row L into three blocks: an upper end portion Lu, a middle portion Lm, and a lower end portion Ld.

[0031] The control unit 23 may determine, for example, a portion of the nozzle row L that is configured with a certain number of nozzles 32 located in the center as an intermediate portion Lm. The control unit 23 may determine, as an upper end portion Lu, a portion that is located above the intermediate portion Lm in the vertical direction Z. The control unit 23 may determine, as a lower end portion Ld, a portion that is located below the intermediate portion Lm in the vertical direction Z. The control unit 23 may determine, as a lower portion than the introduction port 41, the lower end portion Ld. The number of nozzles 32 that configure the upper end portion Lu may be approximately the same as the number of nozzles 32 that configure the lower end portion Ld, or may be different.

[0032] The control unit 23 may set the discharge amount when flushing for each nozzle 32 or for each block. For example, the control unit 23 may cause the nozzles 32 at the upper end portion Lu to discharge a first discharge amount of liquid when flushing. The control unit 23 may cause the nozzles 32 at the middle portion Lm to discharge a second discharge amount of liquid when flushing. The control unit 23 may cause the nozzles 32 at the lower end portion Ld to discharge a third discharge amount of liquid when flushing.

[0033] The first discharge amount may be an amount discharged from one nozzle 32, or may be a total amount discharged from the multiple nozzles 32 that constitute the upper end portion Lu. Similarly, the second discharge amount may be an amount discharged from one nozzle 32, or may be a total amount discharged from the multiple nozzles 32 that constitute the middle portion Lm. The third discharge amount may be an amount discharged from one nozzle 32, or may be a total amount discharged from the multiple nozzles 32 that constitute the lower end portion Ld.

[0034] The control unit 23 may change at least one of the first discharge amount, the second discharge amount, and the third discharge amount according to the discharge conditions. Specifically, the control unit 23 may make the first discharge amount greater than each of the second discharge amount and the third discharge amount. The control unit 23 may perform flushing by making the discharge amount from one or more nozzles 32 constituting an upper end portion Lu of the nozzle row L, among the multiple nozzles 32 constituting the nozzle row L, greater than the discharge amounts from the other multiple nozzles 32.

[0035] For example, in the initial state where the degree of settling of the liquid in the common liquid chamber 39 is low, the change in concentration compared to the state where the liquid has not settled is greater in the upper portion than in the lower portion. That is, in the initial state, the effect on image quality of the liquid ejected by the nozzles 32 at the upper end portion Lu is greater than the effect on image quality of the liquid ejected by the nozzles 32 at the lower end portion Ld. Therefore, by increasing the first ejection amount ejected from the upper end portion Lu, flushing can be performed efficiently.

[0036] The control unit 23 may set the third discharge amount to be greater than each of the first discharge amount and the second discharge amount. The control unit 23 may perform flushing by setting the discharge amount from one or more nozzles 32 constituting the lower end portion Ld of the nozzle row L, among the multiple nozzles 32 constituting the nozzle row L, to be greater than the discharge amounts from the other multiple nozzles 32.

[0037] The control unit 23 may set the first discharge amount to be greater than the second discharge amount. The control unit 23 may set the third discharge amount to be greater than each of the first discharge amount and the second discharge amount. The control unit 23 may perform flushing by setting the discharge amount from one or more nozzles 32 constituting the upper end portion Lu of the nozzle array L and one or more nozzles 32 constituting the lower end portion Ld of the nozzle array L to be greater than the discharge amount from the other one or more nozzles 32, among the multiple nozzles 32 constituting the nozzle array L. The control unit 23 may perform flushing by setting the discharge amount from one or more nozzles 32 constituting the lower end portion Ld of the nozzle array L to be smaller than the discharge amount from one or more nozzles 32 constituting the upper end portion Lu of the nozzle array L, and the discharge amount from the other one or more nozzles 32, in this order.

[0038] As sedimentation of the liquid in the common liquid chamber 39 progresses, the effect on image quality of the liquid discharged by the nozzles 32 at the lower end Ld becomes greater than the effect on image quality of the liquid discharged by the nozzles 32 at the upper end Lu. At this time, the concentration of the liquid discharged by the nozzles 32 at the middle portion Lm is close to a state where the liquid has not settled. Therefore, by increasing the third discharge amount discharged from the lower end Ld and decreasing the third discharge amount discharged from the middle portion Lm, flushing can be performed efficiently.

[0039] The longer the time that the liquid in the common liquid chamber 39 is left without being ejected, the greater the degree of settling. The control unit 23 may be capable of measuring the non-ejection time during which the liquid is not ejected from the liquid ejection head 17. The non-ejection time may be the time that has elapsed without liquid being introduced into the common liquid chamber 39. The non-ejection time may be the time from when the previous printing is performed until when the next printing is performed. When the non-ejection time before printing is performed is a first time, the control unit 23 may increase the ejection amount in flushing compared to when the non-ejection time before printing is performed is a second time that is shorter than the first time.

[0040] The higher the temperature of the liquid, the lower the viscosity of the liquid, and therefore the more likely it is that sedimentation will occur. The control unit 23 may be capable of measuring the temperature of the liquid. The control unit 23 may indirectly measure the temperature of the liquid, for example, by measuring the temperature of the liquid ejection head 17 or the air temperature of the environment in which the liquid ejection device 11 is installed. The control unit 23 may increase the ejection amount during flushing when the temperature of the liquid is a first temperature, compared to when the temperature of the liquid is a second temperature lower than the first temperature.

[0041] When increasing the discharge amount, the control unit 23 may increase at least one of the first discharge amount, the second discharge amount, and the third discharge amount, or may increase the total amount of the first discharge amount, the second discharge amount, and the third discharge amount.

[0042] <Operation of the First Embodiment> The operation of this embodiment will be described. In liquid containing pigment components, the pigment components may settle within the common liquid chamber 39. When settling occurs, the concentration of the liquid changes gradually within the common liquid chamber 39. That is, in the common liquid chamber 39, the concentration becomes higher at the lower part and lower at the upper part. The nozzles 32 at the lower end Ld eject liquid with a higher pigment content, and the nozzles 32 at the upper end Lu eject liquid with a lower pigment content. When printing is performed in this state, the color will differ between the part printed by the nozzles 32 at the lower end Ld and the part printed by the nozzles 32 at the upper end Lu.

[0043] Therefore, the control unit 23 performs flushing before printing or the like to discharge liquid from the liquid ejection head 17. The control unit 23 performs flushing, which is the ejection of liquid unrelated to printing from the multiple nozzles 32 at an ejection amount based on the height difference of the multiple nozzles 32.

[0044] The multiple nozzle rows L that eject the same type of liquid overlap in the transport direction Dc. When printing on the medium 20, the upper end Lu of the first nozzle row L1 ejects liquid so as to overlap an area printed by the lower end Ld of the second nozzle row L2. The control unit 23 ejects the dark liquid ejected by the nozzles 32 at the lower end Ld and the light liquid ejected by the nozzles 32 at the upper end Lu in an overlapping manner, thereby making the color closer to the color of the liquid ejected by the nozzles 32 in the middle portion Lm.

[0045] <Advantages of the First Embodiment> The effects of this embodiment will be described. (1-1) The control unit 23 ejects liquid from the multiple nozzles 32 at an ejection amount based on the elevation difference between the multiple nozzles 32. The elevation difference between the nozzles 32 affects the degree of sedimentation. Therefore, flushing can be performed at an ejection amount that matches the degree of sedimentation. Therefore, it is possible to reduce the amount of liquid consumed while suppressing the effect of sedimentation on image quality.

[0046] (1-2) The control unit 23 increases the ejection amount from one or more nozzles 32 that constitute the lower end Ld among the multiple nozzles 32 that constitute the nozzle row L. As a result, it is possible to discharge a large amount of liquid with a high concentration among the liquid that has settled and become uneven in concentration. Therefore, it is possible to efficiently suppress the effect of sedimentation on image quality.

[0047] (1-3) The control unit 23 increases the ejection amount from one or more nozzles 32 that constitute the upper end portion Lu among the multiple nozzles 32 that constitute the nozzle row L. As a result, it is possible to discharge a large amount of the liquid that has become low in concentration among the liquid that has settled and become uneven in concentration. Therefore, it is possible to efficiently suppress the effect of the settlement on the image quality.

[0048] (1-4) The control unit 23 increases the ejection amount from one or more nozzles 32 constituting the upper end portion Lu and one or more nozzles 32 constituting the lower end portion Ld among the multiple nozzles 32 constituting the nozzle row L. As a result, it is possible to eject more of the liquid with lower concentration and the liquid with higher concentration among the liquid that has settled and become uneven in concentration. Therefore, it is possible to efficiently suppress the effect of the settlement on the image quality.

[0049] (1-5) The control unit 23 increases the ejection amount from one or more nozzles 32 that constitute the lower end Ld among the multiple nozzles 32 that constitute the nozzle row L. The control unit 23 then increases the ejection amount from one or more nozzles 32 that constitute the upper end Lu among the multiple nozzles 32 that constitute the nozzle row L. As a result, it is possible to discharge more of the liquid that has become high-concentration and the liquid that has become low-concentration among the liquid that has settled and caused a concentration imbalance. Therefore, it is possible to efficiently suppress the effect of sedimentation on image quality.

[0050] (1-6) When the undischarged time is long, the control unit 23 increases the discharge amount in flushing compared to when the undischarged time is short. Since sedimentation progresses with the passage of time, flushing can be performed with a discharge amount according to the degree of sedimentation.

[0051] (1-7) The upper end portion Lu of the first nozzle row L1 and the lower end portion Ld of the second nozzle row L2 overlap in the transport direction Dc. Therefore, the liquid ejected by the nozzles 32 at the upper end portion Lu and the liquid ejected by the nozzles 32 at the lower end portion Ld can be printed in an overlapping manner, thereby suppressing the effect of sedimentation on image quality.

[0052] (1-8) The liquid ejection head 17 is a line head. A line head has more nozzle rows L than, for example, a serial head. Therefore, it is possible to more effectively reduce the amount of liquid consumed.

[0053] (1-9) The inlet 41 is provided at a position below the center of the common liquid chamber 39. Therefore, the liquid that has settled in the common liquid chamber 39 can be agitated by the liquid introduced from the inlet 41. Therefore, the amount of liquid ejected by flushing can be reduced.

[0054] [Second embodiment] Next, a second embodiment of the liquid ejection device and the control method for the liquid ejection device will be described with reference to the drawings. Note that this second embodiment differs from the first embodiment in that the liquid ejection head is movably provided. Since the second embodiment is otherwise similar to the first embodiment, the same components are denoted by the same reference numerals and a duplicated description will be omitted.

[0055] The liquid ejection head 17 of this embodiment is a serial head that can move back and forth in the width direction Y. The liquid ejection device 11 performs printing by alternately transporting the medium 20 and moving the liquid ejection head 17. The liquid ejection head 17 prints on the medium 20 by ejecting liquid while moving back and forth in the width direction Y. The liquid ejection head 17 is provided with a nozzle surface 33 that is inclined with respect to the horizontal plane, similar to the first embodiment.

[0056] 5, the liquid ejection head 17 of this embodiment has a nozzle row L composed of a plurality of nozzles 32 aligned in the transport direction Dc. The liquid ejection head 17 may have a plurality of nozzle rows L aligned in the width direction Y. The plurality of nozzle rows L may be composed of a first nozzle 32a to a fourth nozzle 32d that eject different types of liquid. One nozzle row L may be composed of a plurality of nozzles 32 that eject the same type of liquid.

[0057] In each nozzle row L, the nozzles 32 located downstream in the transport direction Dc are located higher in the vertical direction Z than the nozzles 32 located upstream in the transport direction Dc. The control unit 23 performs flushing with a discharge amount based on the height difference of the multiple nozzles 32. The control unit 23 performs flushing in each nozzle row L in the same way as in the first embodiment, and therefore a description thereof will be omitted.

[0058] [Example of change] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0059] The inlet 41 may be provided in the center of the common liquid chamber 39 in the vertical direction Z, or may be provided at a position above the center of the common liquid chamber 39. The control unit 23 may make the discharge amount from the nozzle 32 located away from the inlet 41 greater than the discharge amount from the nozzle 32 located closer to the inlet 41. This makes it easier for the liquid in the common liquid chamber 39 to flow. For example, when the inlet 41 is located at the center of the common liquid chamber 39, the control unit 23 may make each of the first discharge amount and the second discharge amount greater than the third discharge amount. When the inlet 41 is located below the center of the common liquid chamber 39, the control unit 23 may make the first discharge amount greater than each of the second discharge amount and the third discharge amount.

[0060] The control unit 23 may shift the timing of ejecting the liquid at the upper end Lu, the middle portion Lm, and the lower end Ld. For example, the control unit 23 may eject the liquid from the nozzle 32 located away from the inlet 41 earlier than the timing of ejecting the liquid from the nozzle 32 located close to the inlet 41. Specifically, when the inlet 41 is located at a lower position, the control unit 23 may eject the liquid from the nozzle 32 at the upper end Lu first, and then eject the liquid from the nozzle 32 at the lower end Ld. When the liquid is ejected from the nozzle 32 at the upper end Lu first, the liquid with a high concentration that has settled in the common liquid chamber 39 can be made to flow in a rolling manner. In other words, the liquid in the common liquid chamber 39 can be stirred.

[0061] The control unit 23 may perform flushing by ejecting liquid from one or more nozzles 32 that constitute the upper end portion Lu or the lower end portion Ld. The control unit may perform flushing by ejecting liquid from one or more nozzles 32 that constitute the upper end portion Lu and one or more nozzles 32 that constitute the lower end portion Ld. When performing flushing, the control unit 23 may not eject liquid from the multiple nozzles 32 that constitute the middle portion Lm. The second ejection amount may be zero.

[0062] The control unit 23 may change the ejection amount depending on the type of liquid, for example. The control unit 23 may increase the ejection amount in the nozzle row L that ejects a liquid that is prone to settling compared to the nozzle row L that ejects a liquid that is not prone to settling.

[0063] The liquid ejection head 17 may be capable of ejecting a liquid containing a pigment component and a liquid not containing a pigment component. In this case, the control unit 23 may perform flushing in the nozzle row L that ejects the liquid containing a pigment component with a ejection amount based on the elevation difference of the nozzles 32. Also, in this case, the control unit 23 may perform flushing in the nozzle row L that ejects the liquid not containing a pigment component with the same amount from all the nozzles, without performing flushing in the ejection amount based on the elevation difference of the nozzles 32.

[0064] Even when the control unit 23 sets the first discharge amount to be greater than each of the second discharge amount and the third discharge amount, the control unit 23 may change the discharge amount depending on the non-discharge time, the temperature of the liquid, and the like. The amount of liquid discharged from the nozzles 32 by flushing may be constant. The control unit 23 may discharge a preset amount of liquid regardless of the undischarged time, the temperature of the liquid, the timing of flushing, and the like.

[0065] The liquid ejection device 11 may be a liquid ejection device that ejects or ejects liquid other than ink. The state of the liquid ejected from the liquid ejection device as minute droplets includes granular, teardrop, and thread-like tails. The liquid here may be any material that can be ejected from the liquid ejection device. For example, the liquid may be any state in which the substance is in a liquid phase, and includes fluids such as high or low viscosity liquids, sols, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals, and metal melts. The liquid includes not only liquids as one state of matter, but also particles of functional materials made of solids such as pigments and metal particles dissolved, dispersed, or mixed in a solvent. Representative examples of liquids include inks and liquid crystals as described in the above embodiment. Here, the ink includes various liquid compositions such as general water-based inks and oil-based inks, as well as gel inks and hot melt inks. Specific examples of the liquid ejection device include a device that ejects a liquid containing materials such as electrode materials and color materials in a dispersed or dissolved form, which are used in the manufacture of liquid crystal displays, electroluminescence displays, surface-emitting displays, and color filters. The liquid ejection device may be a device that ejects biological organic matter used in the manufacture of biochips, a device that ejects liquid as a sample used as a precision pipette, a textile printing device, a microdispenser, or the like. The liquid ejection device may be a device that ejects lubricating oil at a pinpoint onto precision machinery such as a watch or camera, or a device that ejects transparent resin liquid such as ultraviolet curing resin onto a substrate to form a micro hemispherical lens, optical lens, or the like used in optical communication elements. The liquid ejection device may be a device that ejects an etching liquid such as an acid or alkali to etch a substrate or the like.

[0066] [Definition] The term "at least one" as used herein means "one or more" of the desired options. As an example, the term "at least one" as used herein means "only one option" or "both of two options" if the number of options is two. As another example, the term "at least one" as used herein means "only one option", "any combination of two options", or "any combination of three or more options" if the number of options is three or more.

[0067] [Note] The technical ideas and effects obtained from the above-described embodiment and modified examples will be described below.

[0068] (A) A liquid ejection device includes a liquid ejection head that ejects liquid from a plurality of nozzles in an ejection direction intersecting the vertical direction onto a transported medium to perform printing, and a control unit that controls the liquid ejection head, wherein the liquid contains a pigment component, and the liquid ejection head is provided with a nozzle row in which a plurality of the nozzles are arranged in a line, and the control unit performs flushing, which is the ejection of the liquid unrelated to the printing from the plurality of nozzles in an ejection amount based on the elevation difference between the plurality of nozzles.

[0069] According to this configuration, the control unit ejects liquid from the multiple nozzles at an ejection amount based on the elevation difference between the multiple nozzles. The elevation difference between the nozzles affects the degree of sedimentation. Therefore, flushing can be performed at an ejection amount that matches the degree of sedimentation. Therefore, it is possible to reduce the amount of liquid consumed while suppressing the impact of sedimentation on image quality.

[0070] (B) In the liquid ejection device, the control unit may perform the flushing by making the ejection amount from one or more nozzles that constitute a lower end of the nozzle row, among the multiple nozzles that constitute the nozzle row, greater than the ejection amount from the other multiple nozzles.

[0071] According to this configuration, the control unit increases the ejection amount from one or more nozzles that constitute the lower end of the nozzle row. As a result, it is possible to discharge a large amount of liquid with a high concentration out of the liquid that has settled and become uneven in concentration. This makes it possible to efficiently suppress the effect of sedimentation on image quality.

[0072] (C) In the liquid ejection device, the control unit may perform the flushing by making the ejection amount from one or more nozzles that constitute an upper end of the nozzle row, among the multiple nozzles that constitute the nozzle row, greater than the ejection amount from the other multiple nozzles.

[0073] According to this configuration, the control unit increases the ejection amount from one or more nozzles that constitute the upper end of the nozzle row. This makes it possible to discharge a large amount of the liquid that has settled and become uneven in concentration. This makes it possible to efficiently suppress the effect of the settlement on image quality.

[0074] (D) In ​​the liquid ejection device, the control unit may perform the flushing by increasing the ejection amount from one or more nozzles constituting an upper end of the nozzle row and one or more nozzles constituting a lower end of the nozzle row, among the multiple nozzles constituting the nozzle row, more than the ejection amount from the other one or more nozzles.

[0075] According to this configuration, the control unit increases the ejection amount from one or more nozzles constituting the upper end and one or more nozzles constituting the lower end of the nozzle row. As a result, it is possible to eject more of the liquid with lower concentration and the liquid with higher concentration out of the liquid that has settled and become uneven in concentration. This makes it possible to efficiently suppress the effect of the settlement on image quality.

[0076] (E) In the liquid ejection device, the control unit may perform the flushing by decreasing, in the order of: the ejection amount from one or more nozzles constituting a lower end of the nozzle row; the ejection amount from one or more nozzles constituting an upper end of the nozzle row; and the ejection amount from one or more other nozzles.

[0077] According to this configuration, the control unit increases the ejection amount from one or more nozzles that constitute the lower end of the multiple nozzles that constitute the nozzle row. The control unit then increases the ejection amount from one or more nozzles that constitute the upper end of the multiple nozzles that constitute the nozzle row. As a result, it is possible to discharge more of the liquid that has become high concentration and the liquid that has become low concentration out of the liquid that has settled and caused a concentration imbalance. Therefore, it is possible to efficiently suppress the effect of sedimentation on image quality.

[0078] (F) In the liquid ejection device, the control unit may be capable of measuring a non-ejection time during which the liquid is not ejected from the liquid ejection head, and when the non-ejection time until the printing is performed is a first time, the ejection amount during the flushing may be greater than when the non-ejection time until the printing is performed is a second time that is shorter than the first time.

[0079] According to this configuration, the control unit increases the discharge amount during flushing when the undischarged time is long compared to when the undischarged time is short. Since sedimentation progresses over time, flushing can be performed with a discharge amount according to the degree of sedimentation.

[0080] (G) In the liquid ejection device, the liquid ejection head may have a first nozzle row which is the nozzle row, and a second nozzle row which is aligned with the first nozzle row in the width direction and ejects the same type of liquid as the first nozzle row, and one or more nozzles which form an upper end of the first nozzle row and one or more nozzles which form a lower end of the second nozzle row may be arranged to overlap in the transport direction.

[0081] According to this configuration, the upper end of the first nozzle row and the lower end of the second nozzle row overlap in the transport direction, so that the liquid ejected by the nozzles at the upper end and the liquid ejected by the nozzles at the lower end can be printed in an overlapping manner, thereby suppressing the effect of sedimentation on image quality.

[0082] (H) In the liquid ejection device, the liquid ejection head may be a line head extending in the width direction. According to this configuration, the liquid ejection head is a line head, which has more nozzle rows than, for example, a serial head, and therefore it is possible to more effectively reduce the amount of liquid consumed.

[0083] (I) A method for controlling a liquid ejection device includes a liquid ejection head that ejects liquid from a plurality of nozzles in an ejection direction intersecting with a vertical direction onto a transported medium to perform printing, the liquid containing a pigment component, and the liquid ejection head is provided with a nozzle row in which a plurality of the nozzles are arranged side by side, and includes performing flushing, which is the ejection of the liquid unrelated to the printing from the plurality of nozzles in an ejection amount based on the height difference between the plurality of nozzles. This method can achieve the same effects as the liquid ejection device described above.

[0084] (J) The method of controlling the liquid ejection device may include performing the flushing by increasing the ejection amount from one or more nozzles constituting a lower end of the nozzle row among the plurality of nozzles constituting the nozzle row, compared to the ejection amount from the remaining plurality of nozzles. This method can achieve the same effects as the liquid ejection device described above.

[0085] (K) The method of controlling the liquid ejection device may include performing the flushing by increasing the ejection amount from one or more nozzles constituting an upper end of the nozzle row among the plurality of nozzles constituting the nozzle row, compared to the ejection amount from the remaining nozzles. This method can achieve the same effects as the liquid ejection device described above.

[0086] (L) The method of controlling the liquid ejection device may include performing the flushing by increasing the ejection amount from one or more nozzles constituting the upper end of the nozzle row and one or more nozzles constituting the lower end of the nozzle row, among the multiple nozzles constituting the nozzle row, more than the ejection amount from one or more other nozzles. This method can achieve the same effects as the liquid ejection device described above.

[0087] (M) The method of controlling the liquid ejection device may include performing the flushing by decreasing the ejection amount from one or more nozzles constituting the lower end of the nozzle row, the ejection amount from one or more nozzles constituting the upper end of the nozzle row, and the ejection amount from one or more other nozzles in that order. This method can achieve the same effects as the liquid ejection device described above.

[0088] (N) A method of controlling a liquid ejection device may include measuring a non-ejection time during which the liquid is not ejected from the liquid ejection head, and increasing the ejection amount in the flushing when the non-ejection time until the printing is performed is a first time, compared to when the non-ejection time until the printing is performed is a second time that is shorter than the first time. This method can achieve the same effects as the liquid ejection device described above. [Explanation of symbols]

[0089] Reference Signs List 11...liquid ejection device, 12...housing, 13...cassette, 14...feeding section, 15...transporting section, 16...holding section, 17...liquid ejection head, 18...stacker, 20...medium, 21...transport path, 23...control section, 25...feeding roller, 26...separating section, 28...transporting roller, 29...transporting belt, 30...pulley, 32...nozzle, 32a...first nozzle, 32b...second nozzle, 32c...third nozzle 3 nozzle, 32d...fourth nozzle, 33...nozzle surface, 35...unit head, 37...nozzle group, 39...common liquid chamber, 40...cavity, 41...inlet, C...center, Dc...transport direction, Dj...ejection direction, L...nozzle row, L1 to L6...first nozzle row to sixth nozzle row, La...first distance, Lb...second distance, Ld...lower end, Lm...middle portion, Lu...upper end, Y...width direction, Z...vertical direction.

Claims

1. a liquid ejection head that ejects liquid from a plurality of nozzles onto a medium being transported in an ejection direction that intersects with a vertical direction to perform printing; A control unit for controlling the liquid ejection head; Equipped with The liquid contains a pigment component, The liquid ejection head is provided with a nozzle row in which a plurality of the nozzles are arranged in a row, The control unit is A liquid ejection device comprising: a plurality of nozzles that ejects liquid in an amount based on a height difference between the plurality of nozzles; and a flushing process that ejects the liquid from the plurality of nozzles in an amount unrelated to printing.

2. The control unit is The liquid ejection device according to claim 1, characterized in that the flushing is performed by making the ejection amount from one or more nozzles constituting the lower end of the nozzle row, among the multiple nozzles constituting the nozzle row, greater than the ejection amount from the other multiple nozzles.

3. The control unit is The liquid ejection device according to claim 1, characterized in that the flushing is performed by making the ejection amount from one or more nozzles constituting the upper end of the nozzle row, among the multiple nozzles constituting the nozzle row, greater than the ejection amount from the other multiple nozzles.

4. The control unit is The liquid ejection device according to claim 1, characterized in that the flushing is performed by making the ejection amount from one or more nozzles that form the upper end of the nozzle row and one or more nozzles that form the lower end of the nozzle row greater than the ejection amount from the other one or more nozzles.

5. The control unit is The liquid ejection device according to claim 1, characterized in that the flushing is performed by decreasing the ejection amount from one or more nozzles constituting the lower end of the nozzle row, the ejection amount from one or more nozzles constituting the upper end of the nozzle row, and the ejection amount from one or more other nozzles, in that order.

6. The control unit is a non-ejection time during which the liquid is not ejected from the liquid ejection head can be measured; A liquid ejection device as described in any one of claims 1 to 5, characterized in that when the unejected time until the printing is performed is a first time, the ejection amount during the flushing is made larger than when the unejected time until the printing is performed is a second time which is shorter than the first time.

7. The liquid ejection head includes: a first nozzle row, which is the nozzle row; a second nozzle row arranged next to the first nozzle row in the width direction and configured to eject the same type of liquid as the first nozzle row; having A liquid ejection device according to any one of claims 1 to 5, characterized in that one or more of the nozzles constituting the upper end of the first nozzle row and one or more of the nozzles constituting the lower end of the second nozzle row are arranged to overlap in the transport direction.

8. 8. The liquid ejection apparatus according to claim 7, wherein the liquid ejection head is a line head extending in the width direction.

9. a liquid ejection head that ejects liquid from a plurality of nozzles onto a medium being transported in an ejection direction that intersects with a vertical direction to perform printing; The liquid contains a pigment component, A method for controlling a liquid ejection device, the liquid ejection head being provided with a nozzle row in which a plurality of the nozzles are arranged in a row, the method comprising: A method for controlling a liquid ejection device, comprising performing flushing, which is ejection of the liquid unrelated to printing, from a plurality of the nozzles in an amount based on a height difference between the plurality of the nozzles.

10. The method for controlling a liquid ejection device according to claim 9, further comprising performing the flushing by increasing the ejection amount from one or more nozzles constituting a lower end of the nozzle row among the plurality of nozzles constituting the nozzle row, compared to the ejection amount from the remaining plurality of nozzles.

11. The method for controlling a liquid ejection device according to claim 9, further comprising performing the flushing by increasing the ejection amount from one or more nozzles constituting an upper end of the nozzle row among the plurality of nozzles constituting the nozzle row, compared to the ejection amount from the remaining plurality of nozzles.

12. The control method for a liquid ejection device according to claim 9, further comprising performing the flushing by increasing the ejection amount from one or more nozzles constituting the upper end of the nozzle row and one or more nozzles constituting the lower end of the nozzle row, among the plurality of nozzles constituting the nozzle row, more than the ejection amount from one or more other nozzles.

13. The control method for a liquid ejection device according to claim 9, further comprising performing the flushing by decreasing the ejection amount from one or more nozzles constituting the lower end of the nozzle row, the ejection amount from one or more nozzles constituting the upper end of the nozzle row, and the ejection amount from one or more other nozzles, in that order.

14. measuring a non-ejection time during which the liquid is not ejected from the liquid ejection head; When the undischarged time until the printing is performed is a first time, the ejection amount in the flushing is made larger than when the undischarged time until the printing is performed is a second time that is shorter than the first time; The method for controlling the liquid ejection device according to any one of claims 9 to 13, further comprising:

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