Liquid ejection head, liquid ejection recording device, liquid ejection head control method, and liquid ejection recording device control method

Abstract

A liquid ejection head (4) comprises: a plurality of nozzles; a plurality of actuators corresponding to the plurality of nozzles; and a drive control unit (51) capable of causing liquid to be ejected from the plurality of nozzles by inputting a drive voltage to the actuators to drive the actuators. The drive control unit outputs, as the drive voltage, a first drive waveform for causing liquid to be ejected using a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform for causing liquid to be ejected using a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage.

Description

Liquid ejection head, liquid ejection recording apparatus, liquid ejection head control method, and liquid ejection recording apparatus control method

[0001] The present disclosure relates to a liquid ejection head, a liquid ejection recording apparatus, a method for controlling a liquid ejection head, and a method for controlling a liquid ejection recording apparatus.

[0002] Liquid ejection recording devices such as inkjet printers include a liquid ejection head that ejects ink for forming an image onto a recording medium. For example, the liquid ejection head includes a piezoelectric element such as a piezo element, a liquid pressure chamber, and a liquid ejection orifice. The liquid ejection head pressurizes the liquid filled in the liquid pressure chamber by displacing the piezoelectric element, causing the liquid to be ejected from the liquid ejection orifice. It is known that the piezoelectric element is displaced in response to a drive signal that indicates a pulse-like voltage change.

[0003] Conventionally, in order to form various images on a recording medium, a technique has been known in which multiple types of droplets, such as large droplets, medium droplets, and small droplets, whose ejection volume varies depending on the pixel size of the image, are ejected based on voltage changes in the drive signal. In such conventional techniques, a portion of a drive waveform corresponding to a required ejection volume is extracted from a single drive waveform formed by connecting together voltage changes corresponding to multiple ejection volumes, and the drive voltage is input to the corresponding piezoelectric element.

[0004] A liquid ejection head according to a first aspect of the present disclosure comprises a plurality of nozzles, a plurality of actuators corresponding to the plurality of nozzles, and a drive control unit capable of ejecting liquid from the plurality of nozzles by inputting a drive voltage to the actuators to drive the actuators, wherein the drive control unit outputs, as the drive voltage, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage.

[0005] A liquid ejection recording device according to a second aspect of the present disclosure comprises a liquid ejection head capable of ejecting liquid, having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, a medium support unit that supports a recording medium so as to face the liquid ejection head, and a drive control unit that is capable of ejecting droplets from the plurality of nozzles by inputting a drive voltage to the actuator to drive the actuator, wherein the drive control unit outputs, as the drive voltage, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage.

[0006] A control method for a liquid ejection head according to a third aspect of the present disclosure is a control method for a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, comprising: preparing, as drive voltages for the actuators, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage; and inputting the first drive waveform or the second drive waveform into the actuators to drive the actuators according to the required volume of liquid to be ejected from the nozzles, thereby ejecting liquid from the plurality of nozzles.

[0007] A control method for a liquid ejection recording device according to a fourth aspect of the present disclosure is a control method for a liquid ejection recording device including a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, and a medium support unit that supports a recording medium so as to face the liquid ejection head, the control method comprising: preparing, as drive voltages for the actuator, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage; and inputting the first drive waveform or the second drive waveform into the actuator to drive the actuator according to the required volume of liquid to be ejected from the nozzles, thereby ejecting liquid from the plurality of nozzles.

[0008] FIG. 1 is a perspective view showing the overall configuration of an image forming apparatus according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a block diagram showing the electrical configuration of an image forming apparatus according to an embodiment of the present disclosure. FIG. 4 is a diagram for explaining the principle of liquid ejection by a liquid ejection head. FIG. 4B is a diagram for explaining the principle of liquid ejection by a liquid ejection head. FIG. 4C is a diagram for explaining the principle of liquid ejection by a liquid ejection head. FIG. 5 is a diagram showing basic drive voltages applied to a piezoelectric element of a liquid ejection head. FIG. 6A is a diagram showing drive voltages applied to a piezoelectric element of a liquid ejection head, corresponding to large, medium, and small droplets. FIG. 6B is a diagram showing drive voltages applied to a piezoelectric element of a liquid ejection head, corresponding to large, medium, and small droplets. FIG. 6C is a diagram showing drive voltages applied to a piezoelectric element of a liquid ejection head, corresponding to large, medium, and small droplets. FIG. 7A is a diagram showing drive voltages applied to a piezoelectric element of a liquid ejection head, showing drive voltages selected corresponding to large, medium, and small droplets. Fig. 7B is a diagram showing the drive voltages applied to the piezoelectric elements of the liquid ejection head, and shows the drive voltages selected corresponding to large, medium, and small droplets. Fig. 8A is a schematic diagram showing the ejection state of droplets according to the drive voltage. Fig. 8B is a schematic diagram showing the ejection state of droplets according to the drive voltage. Fig. 9 is a schematic diagram of a dual-liquid head capable of ejecting two types of liquid from a single head.

[0009] A liquid ejection head, a liquid ejection recording apparatus, and a control method thereof according to an embodiment of the present disclosure will be described below with reference to the drawings. In the following embodiment, an inkjet printer equipped with an ink head that ejects ink for forming an image on a wide, long recording medium will be exemplified as a specific example of a liquid ejection recording apparatus. Inkjet printers are suitable for digital textile printing, which uses an inkjet method to print images such as letters and patterns on recording media made of fabrics such as woven fabrics and knitted fabrics. Of course, the liquid ejection recording apparatus according to the present disclosure can also be used to print various images on recording media such as paper sheets and resin sheets.

[0010] Fig. 1 is a perspective view showing the overall configuration of an inkjet printer 1 according to this embodiment, and Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1. The inkjet printer 1 is a printer that prints images on a wide and long workpiece W (recording medium) using an inkjet method, and includes a device frame 10, and a workpiece transport unit 20 (transport unit) and carriage 3 that are incorporated into this device frame 10. In this embodiment, the left-to-right direction is the main scanning direction when printing on the workpiece W, and the direction from rear to front is the sub-scanning direction (the direction in which the workpiece W is transported, which intersects with the main scanning direction).

[0011] The device frame 10 forms a framework for mounting various components of the inkjet printer 1. The work transport unit 20 is a mechanism that intermittently feeds (transports) the work W so that the work W progresses in a transport direction from rear to front in a printing area where inkjet printing processing is performed. The carriage 3 is equipped with the ink head 4 as well as a pre-treatment liquid head, a post-treatment liquid head, and a sub-tank 7 (described below), and moves back and forth in the main scanning direction (left and right direction) during the inkjet printing processing.

[0012] The device frame 10 includes a central frame 111, a right frame 112, and a left frame 113. The central frame 111 forms a framework for mounting various components of the inkjet printer 1, and has a left-to-right width corresponding to the work transport section 20. The right frame 112 and left frame 113 are erected to the right and left of the central frame 111, respectively. Between the right frame 112 and the left frame 113 is the printing area 12 where printing processing is performed on the work W.

[0013] The right frame 112 forms the maintenance area 13. The maintenance area 13 is an area where the carriage 3 is retracted when the printing process is not being performed. In the maintenance area 13, cleaning processes, purging processes, etc. are performed on the nozzles (ejection holes) of the ink heads 4 and the pre-treatment liquid head and post-treatment liquid head described below, and the nozzles are also capped. The left frame 113 forms a turn-around area 14 for the carriage 3. The turn-around area 14 is an area where the carriage 3 temporarily enters when it performs a main scan in the opposite direction after performing a main scan in the opposite direction across the printing area 12 from right to left during the printing process.

[0014] A carriage guide 15 for moving the carriage 3 back and forth in the left-right direction is attached to the upper side of the device frame 10. The carriage guide 15 is a flat plate-shaped member that is long in the left-right direction, and is disposed above the work transport unit 20. A timing belt 16 is attached to the carriage guide 15 so as to be able to move in a circular motion in the left-right direction (main scanning direction). The timing belt 16 is an endless belt that is driven to move in a circular motion in the left or right direction.

[0015] The carriage guide 15 is equipped with a pair of upper and lower guide rails 17 that extend parallel to the left and right and that hold the carriage 3 in a state that allows it to move back and forth in the main scanning direction. The carriage 3 is engaged with the guide rails 17. The carriage 3 is also fixed to a timing belt 16. As the timing belt 16 moves orbitally left and right, the carriage 3 moves left and right along the carriage guide 15 while being guided by the guide rails 17.

[0016] 2 , the workpiece transport unit 20 has an endless belt 20H, a drive roller 21, and a driven roller 22. The drive roller 21 and the driven roller 22 tension the endless belt 20H. When the drive roller 21 rotates, the endless belt 20H rotates in the direction of arrow H1, transporting the workpiece W so that it passes below the carriage 3.

[0017] The carriage 3 moves back and forth in a main scanning direction (left and right direction in this embodiment) that intersects with the transport direction (orthogonal in this embodiment) while being cantilevered on the guide rail 17. The carriage 3 includes a carriage frame 30, and an ink head 4, a pre-treatment liquid head 5, a post-treatment liquid head 6, and a sub-tank 7 that are mounted on the carriage frame 30. The carriage frame 30 includes a head support frame 31 and a back frame 32.

[0018] The head support frame 31 is a horizontal plate that holds the heads 4 to 6. The back frame 32 is a vertical plate that extends upward from the rear edge of the head support frame 31. The rear end of the head support frame 31 is supported in a cantilevered manner by the back frame 32. As described above, the timing belt 16 is fixed to the back frame 32. The guide rail 17 is engaged with the back frame 32.

[0019] Note that a cantilevered state refers to a state in which the guide rail 17 that holds the carriage 3 is present on only one side of the carriage 3, either upstream or downstream from the center of the carriage 3 in the conveying direction, and the side opposite the side where the guide rail 17 is present is not held.

[0020] Each ink head 4 has a number of nozzles (ink ejection holes) that eject ink droplets using an ejection method such as a piezo method using a piezo element or a thermal method using a heating element, and ink passages that guide the ink to the nozzles. For example, a water-based pigment ink containing a water-based solvent, pigment, and binder resin can be used as the ink. The multiple ink heads 4 in this embodiment are each capable of ejecting different inks. Each head is mounted on a head support frame 31 of the carriage 3.

[0021] A series of heads arranged along the main scanning direction, which are made up of the ink heads 4 and treatment liquid heads, is referred to as a row of heads, or simply as a row. Also, a series of heads arranged along the transport direction F, which are made up of the ink heads 4 and treatment liquid heads, is referred to as a row of heads, or simply as a row.

[0022] The ink ejected from the ink head 4 is not particularly limited, and can be one containing a pigment or a dye. For example, an ink containing a pigment and an aqueous medium can be used. The ink may further contain at least one selected from the group consisting of surfactants, polyols, and binder resin particles, as needed. Examples of pigments include yellow pigments, orange pigments, red pigments, blue pigments, purple pigments, and black pigments. The ink may also contain an anionic pigment. In such cases, the cationic polymer and anionic pigment contained in the post-treatment liquid electrically react and aggregate on the surface of the recording medium, thereby preventing the binder resin contained in the ink from penetrating into the recording medium. This prevents the binder resin from penetrating into the gaps between fibers and bonding the fibers together when the recording medium is fabric. This can improve the texture (feel, etc.) of the fabric to be printed.

[0023] Specifically, anionic pigments having anionic groups such as a carboxyl group, a sulfonic acid group, a phosphate group, a phosphonic acid group, a phenylsulfonic acid group, or a phenylcarboxyl group are more preferred as anionic pigments. The aqueous medium contained in the ink is a medium containing water as its main component. The aqueous medium may function as a solvent or a dispersion medium. Specific examples of aqueous media include water and mixtures of water and polar solvents. Examples of polar solvents contained in aqueous media include methanol, ethanol, isopropyl alcohol, butanol, and methyl ethyl ketone. Furthermore, the ink contains a surfactant, which improves the wettability of the ink to the recording medium.

[0024] The binder resin particles contained in the ink exist in a dispersed state in an aqueous medium. The binder resin particles function as a binder that bonds the subject to be printed with the pigment. Therefore, by including binder resin particles in the ink, it is possible to obtain a printed item with excellent pigment fixation. Examples of resins contained in the binder resin particles include urethane resin, (meth)acrylic resin, styrene-(meth)acrylic resin, styrene-maleic acid copolymer, vinylnaphthalene-(meth)acrylic acid copolymer, and vinylnaphthalene-maleic acid copolymer. Urethane resin is preferred as the resin contained in the binder resin particles.

[0025] The binder resin content may be 1% by weight or more and 20% by weight or less, or 2% by weight or more and 10% by weight or less, based on the total weight of the ink. When the binder resin particle content is 1% by weight or more, a recording medium with excellent pigment fixation can be obtained. On the other hand, when the binder resin particle content is 20% by weight or less, the ink can be stably ejected onto the recording medium.

[0026] The processing liquid heads 5 and 6 eject pre-processing liquid for performing a predetermined pre-processing on the workpiece W. The pre-processing liquid is ejected from the processing liquid heads 5 and 6 onto a position on the workpiece W where ink has not yet been ejected from the ink head 4. The processing liquid heads also eject post-processing liquid for performing a predetermined post-processing on the workpiece W to which ink has adhered. The post-processing liquid is ejected from the processing liquid heads onto a position on the workpiece W where ink has been ejected from the ink head 4.

[0027] Any pretreatment liquid can be used. For example, a pretreatment liquid that aggregates the pigment of the ink to improve color development and fixation, as described below, can be used. The pretreatment liquid may also be used to suppress the penetration of the ink into the recording medium, or conversely, to promote the penetration, to print thickly to create a three-dimensional shape, or to impart gloss.

[0028] The pretreatment liquid may contain, for example, a water-soluble cationic polymer, an organic acid salt, and an aqueous medium. Such a pretreatment liquid reacts with and aggregates the pigment contained in the ink to be subsequently printed, improving color development. It can also improve washing fastness and the texture of the fabric. The content of the water-soluble cationic polymer may be 0.1 wt % or more and less than 10 wt % of the total pretreatment liquid. By making the content of the water-soluble cationic polymer less than 10 wt %, sufficient wet rub fastness can be obtained. The aqueous medium contained in the pretreatment liquid can be the same as that of the ink.

[0029] Any post-treatment liquid can be used. For example, a post-treatment liquid that improves texture can be used, as described below. The post-treatment liquid may also be used to provide a coating for protecting the printed ink, to thickly print a three-dimensional shape, or to impart gloss. It may also be used to perform a treatment not directly related to ink printing, such as imparting water repellency to the recording medium.

[0030] The post-treatment liquid may contain, for example, emulsified particles containing silicone oil, a surfactant, and an aqueous medium. That is, the post-treatment liquid is an emulsion in which emulsified particles are dispersed in an aqueous medium, more specifically, an oil-in-water (O / W) emulsion. The silicone oil may contain unmodified silicone oil. Examples of unmodified silicone oil include dimethylpolysiloxane, methylphenylsilicone oil, and methylhydrogensilicone oil. Such a post-treatment liquid can improve the texture.

[0031] The surfactant may include a first surfactant containing an alkyl group having 12 to 14 carbon atoms and a second surfactant containing an alkyl group having 16 to 18 carbon atoms. Polyoxyethylene alkyl ether may be used for both surfactants.

[0032] The aqueous medium contained in the post-treatment liquid can be the same as that of the ink. The post-treatment liquid is basically a non-color-forming treatment liquid that does not develop color even when attached to the workpiece W. The post-treatment liquid and the pre-treatment liquid are basically different treatment liquids. Specifically, the components contained in the post-treatment liquid and the pre-treatment liquid are different.

[0033] Each processing liquid is basically a non-coloring processing liquid that does not develop color even when adhered to the workpiece W. Here, a non-coloring processing liquid refers to a processing liquid that, when printed alone on a recording medium, is not perceived as having developed color with the naked eye. Color here includes colors with a saturation of zero, such as black, white, and gray. A non-coloring processing liquid is basically a transparent liquid, but when viewed in its liquid state, for example, 1 liter of processing liquid may not be completely transparent and may appear slightly white. Such colors are very light, so when printed alone on a recording medium, they cannot be perceived as having developed color with the naked eye. Note that, depending on the type of processing liquid, when printed alone on a recording medium, changes such as gloss may occur on the recording medium, but such a state is not considered to be coloring.

[0034] In this embodiment, the pre-treatment liquid and the post-treatment liquid may be ejected onto almost the entire surface of the workpiece W, or the pre-treatment liquid and the post-treatment liquid may be ejected selectively in accordance with the image to be printed, similar to ink.

[0035] Here, a case where the pretreatment liquid and the posttreatment liquid are selectively ejected will be described. As described above, the pretreatment liquid, ink, and posttreatment liquid are ejected in this order onto the portion of the workpiece W where a color is to be printed in accordance with the image. In this case, the ink may be of one color or multiple colors. In portions where no color is to be printed, i.e., portions where no ink is ejected, the pretreatment liquid and the posttreatment liquid are basically not ejected either. Note that, in order to adjust the image quality of the printed image and the texture of the workpiece W, the selection of the ejection of the pretreatment liquid and the posttreatment liquid may be made to differ from the ejection of the ink. For example, the pretreatment liquid and the posttreatment liquid may be printed in an area slightly larger (for example, the area of ​​a few pixels) than the area printed with ink.

[0036] Openings are provided in the head support frame 31 where the heads are arranged. The ink heads 4 and treatment liquid heads are assembled to the head support frame 31 so as to fit into the respective openings. Nozzles arranged on the bottom end surface of each head are exposed from each opening.

[0037] The subtanks 7 are supported by the carriage 3 above each head via a holding frame (not shown). A subtank 7 is provided corresponding to each head. Each subtank 7 is supplied with ink or treatment liquid (sometimes collectively referred to as liquid) from a cartridge (not shown) or main tank that contains ink and treatment liquid, and supplies these to each head. Each subtank 7 and each head are connected by a conduit (not shown).

[0038] Each subtank 7 may have a supply subtank and a recovery subtank. The supply subtank supplies liquid to the corresponding head. The recovery subtank recovers liquid that was not ejected from the corresponding head. The supply and recovery of liquid are achieved, for example, by applying pressure to the liquid via gas (air) present above the liquid contained in the supply subtank and the recovery subtank. The supply and recovery of liquid are achieved by the pressure difference between the pressure applied to the supply subtank and the pressure applied to the recovery subtank. The pressures applied to each subtank are controlled so that the pressure at the nozzle of each head is approximately 0 (zero, the same as atmospheric pressure) or slightly negative or positive. This allows the nozzle to maintain a meniscus and remain capable of ejecting liquid.

[0039] Liquid may be transferred between the supply subtank, recovery subtank, and main tank as follows: When the liquid in the supply subtank falls below a predetermined level, the liquid in the recovery subtank is transferred to the supply subtank by a pump or the like. This allows the liquid to circulate within the supply subtank, head, and recovery subtank. When the liquid in the recovery subtank falls below a predetermined level, the liquid from the main tank is supplied to the recovery subtank by a pump or the like.

[0040] Supplying liquid adjusted to a constant temperature to the head can stabilize the temperature of the head. The liquid supplied to the head reaches the individual flow paths in which the nozzles are provided via a common flow path (manifold) within the head. When recovering liquid from the head, it is not necessary to recover the liquid supplied to the individual flow paths, and it is also possible to recover only the liquid that has passed through the common flow path. Liquid may be supplied to and recovered from the individual flow paths in which the nozzles are provided, so that the liquid is less likely to stagnate in and around the nozzles. In this case, the liquid recovered from the individual flow paths is recovered, for example, via the common flow path.

[0041] As described above, the inkjet printer 1 according to this embodiment is an all-in-one printer in which the ink head 4 and treatment liquid heads 5 and 6 are mounted on a single carriage 3. With this inkjet printer 1, for example, in the printing process of performing inkjet printing on fabric in digital textile printing, the process of ejecting the pre-treatment liquid and the process of ejecting the post-treatment liquid can be carried out in an integrated manner. This makes it possible to simplify the textile printing process and make the textile printing device more compact.

[0042] Next, the printing method performed by the inkjet printer 1 according to this embodiment will be described. The inkjet printer 1 performs printing processing on the workpiece W using a serial printing method. If the workpiece W is wide, it is not possible to print while continuously feeding the workpiece W. The serial printing method is a printing method in which a carriage 3 carrying ink heads 4 of each color moves back and forth in the main scanning direction, and the workpiece W is intermittently fed in the transport direction, repeatedly.

[0043] The workpiece W after printing with the inkjet printer 1 may be heated and dried by a heater (not shown) or the like provided in the inkjet printer 1. Furthermore, the printed portion of the workpiece W may be transported to a dryer separate from the inkjet printer 1 and dried by that dryer, rather than being wound up on a take-up roller (not shown). The heating temperature is, for example, 120°C or higher and 180°C or lower. The heating time is, for example, 1 minute or higher and 10 minutes or lower. Heating dries volatile components contained in the ink and treatment liquid, facilitating fixation of the ink and treatment liquid to the workpiece W.

[0044] In the above description, the pretreatment liquid is mainly exemplified as one that causes ink to aggregate on the workpiece W, but the pretreatment liquid may also be one that contains a larger amount of resin component than the ink and has the property of binding the fabric and the pigment. In this case, too, the pretreatment liquid is more likely to clog the ink nozzles or adhere to the nozzle surface, so the arrangement of the head and nozzle region as described above is desirable.

[0045] The distance between heads, the distance between nozzle regions, and the distance between heads and nozzle regions are, for example, the distance along the main scanning direction, and refer to the distance between the closest points between them. Alternatively, the distance along the main scanning direction between the centers of gravity of the areas occupied by each head when viewed in a plane may also be considered.

[0046] Unless otherwise specified, the intervals between adjacent heads in the main scanning direction (the intervals between the closest parts of each head, or the intervals between the centers of each head) are the same. Similarly, for a head arrangement with multiple rows described below, the intervals between adjacent heads in the transport direction F (the intervals between the centers of each head) are the same.

[0047] [Principle of Liquid Ejection by Liquid Ejection Head] Next, the principle of liquid ejection by a liquid ejection head will be described. Fig. 3 is a block diagram showing the electrical configuration of a liquid ejection head according to an embodiment of the present disclosure. Figs. 4A, 4B, and 4C are diagrams for explaining the principle of liquid ejection by a liquid ejection head. Fig. 5 is a diagram showing basic driving voltages applied to piezoelectric elements of the liquid ejection head. In the following description, the ink head 4, pre-treatment liquid head 5, and post-treatment liquid head 6 will be collectively referred to as head 50.

[0048] 3 and 4 , the head 50 includes a driver IC (integrated circuit) 51 (drive control unit) and multiple nozzle units 80. The multiple nozzle units 80 provided in one head 50 are aligned in the main scanning direction and the sub-scanning direction. Each view in FIG. 4 is an enlarged cross-sectional view of one nozzle unit 80. The nozzle unit 80 includes an ejection element 81 (actuator), such as a piezoelectric element, a liquid pressure chamber 82 filled with liquid supplied from the subtank 7 via a conduit (not shown), and a nozzle 83 that ejects the liquid from the liquid pressure chamber 82. The ejection element 81 is provided corresponding to each of the multiple nozzles 83 and is driven (displaced) by receiving a drive voltage, thereby ejecting liquid from the corresponding nozzle 83. In this embodiment, the ejection element 81 is made of a piezoelectric element. Three ejection elements 81 are shown in FIG. 3 as an example.

[0049] The driver IC 51 generates a drive voltage for adjusting the volume (size) and discharge timing of the liquid (ink, each treatment liquid) discharged from each discharge element 81 in accordance with information about an image to be formed on the workpiece W, and inputs the drive voltage to the discharge elements 81. Specifically, the driver IC 51 has a head control unit 52 and a plurality of drive signal generation units 53 provided corresponding to each discharge element 81. The driver IC 51 inputs a drive voltage to the discharge elements 81 to drive the discharge elements 81, thereby discharging liquid from the plurality of nozzles 83.

[0050] The head control unit 52 determines the drive waveform of the drive voltage to be input to each ejection element 81 according to information about the image to be formed on the workpiece W, and inputs that information to the corresponding drive signal generation unit 53. In other words, the head control unit 52 has the function of controlling which drive waveform to generate for each ejection element 81. The drive waveform will be described in detail later.

[0051] The drive signal generation unit 53 inputs drive waveforms (drive signals) to the corresponding ejection elements 81 in accordance with drive waveform information (commands) received from the head control unit 52. One drive waveform is generated for each ejection element 81 for each ejection. Note that one ejection may include the ejection of multiple droplets. One ejection basically corresponds to one pixel of an image formed on a recording medium. In this embodiment, the head control unit 52 and the driver IC 51 including the multiple ejection elements 81 have an integrated substrate structure.

[0052] The drive signal of the head 50 is, for example, a pulsed rectangular wave (drive waveform) that periodically fluctuates at a predetermined ejection period (ejection interval), as shown in Fig. 5. The amplitude of the drive signal of the head 50 indicates the voltage applied to the ejection elements 81.

[0053] As an example, when the head 50 starts to be driven by the drive signal, the voltage "VH" that was applied to the ejection element 81 at the end of the previous ejection cycle continues to be applied to the ejection element 81, as shown in region (A) of Fig. 5. This causes the deformed state of the ejection element 81 to be maintained for a certain period of time, as shown in Fig. 4A. Under these conditions, the liquid inside the head 50 forms a meniscus of liquid in the nozzle 83 according to the pressure of the liquid inside the head 50 and the pressure of the outside atmosphere.

[0054] Next, during the period shown in region (B) of Fig. 5, the amplitude of the drive signal becomes VL (=0), and the application of voltage to the ejection element 81 is stopped (shut off). As a result, as shown in Fig. 4B, the ejection element 81 is released from its deformed state, and begins to become parallel to the upper surface of the liquid pressurizing chamber 82. As a result, the liquid in the liquid pressurizing chamber 82 is decompressed, and some of the liquid in the nozzle 83 is drawn into the liquid pressurizing chamber 82.

[0055] 5, voltage "VH" is again applied to the ejection element 81. As a result, as shown in FIG. 4C, the ejection element 81 deforms and the liquid in the liquid pressurizing chamber 82 is pressurized, causing the liquid in the liquid pressurizing chamber 82 to be ejected from the nozzle 83.

[0056] The ejection period differs depending on the drive frequency of the print head. For example, the following periods can be given:

[0057] Drive frequency 30 kHz = 1 sec / 30,000 times = drive cycle (ejection cycle) 33.3 μsec Drive frequency 5 kHz = 1 sec / 5,000 times = drive cycle (ejection cycle) 200 μsec

[0058] Then, depending on the required ejection conditions (such as the amount of liquid ejected), the ON time, OFF time, and number of ON / OFF cycles of the drive signal can be adjusted within this ejection cycle (waveform adjustment).

[0059] In this embodiment, before liquid ejection, the device waits with the voltage "VH" applied, then applies a voltage "VL" lower than the voltage "VH" to increase the volume of the liquid pressurizing chamber 82, and then applies the voltage "VH" again to decrease the volume of the liquid pressurizing chamber 82 (returning it to the standby state). This relationship may be reversed. That is, the voltage "VL" may be higher than the voltage "VH". In this case, the ejection element 81 used is one in which the volume of the liquid pressurizing chamber 82 increases as the applied voltage increases.

[0060] Furthermore, in this embodiment, the volume (amount) of liquid ejected from each ejection element 81 is adjusted to three levels in accordance with the image formed on the workpiece W. In the following description, the droplets will be referred to as large droplets, medium droplets, and small droplets, in order of decreasing volume. These will also be referred to as large dots, medium dots, and small dots. Figures 6A, 6B, and 6C are diagrams showing the drive voltages applied to the piezoelectric elements of the liquid ejection head, corresponding to large droplets, medium droplets, and small droplets. These drive waveforms are different from one another and are each sent to the ejection element 81 over the course of a ejection cycle.

[0061] As shown in FIG. 6A , when two downwardly convex pulses are included between the maximum and minimum values ​​of the drive voltage, two droplets can be ejected from the ejection element 81. The two droplets may be merged into a single droplet (large droplet) during flight by increasing the speed of the later-ejected droplet. The two droplets may not merge and land directly on the recording medium. In this case, the two droplets may spread and merge on the recording medium to form a single pixel, or the two droplets may remain separate on the recording medium to form a single pixel. Alternatively, a single droplet (large droplet) may be ejected. Similarly, as shown in FIG. 6B , when one downwardly convex pulse is included between the maximum and minimum values ​​of the drive voltage, a medium droplet can be ejected from the ejection element 81. In other words, a large droplet is similar to two medium droplets being ejected consecutively. Furthermore, when one downwardly convex short pulse is included between the maximum and minimum values ​​of the drive voltage, as shown in FIG. 6C , a small droplet can be ejected from the ejection element 81. 6A to 6C, the short pulse generated at the end of the drive waveform is for removing residual vibrations occurring in the ejection elements 81.

[0062] Furthermore, in this embodiment, two drive waveforms are prepared in advance in the driver IC 51. Figures 7A and 7B are diagrams showing the drive voltages applied to the piezoelectric elements of the liquid ejection head, and are diagrams showing drive waveforms that can be selected corresponding to large droplets, medium droplets, and small droplets.

[0063] 7A shows a drive waveform for ejecting liquid at a potential (potential difference) between the maximum value VH and minimum value VL of the drive voltage. The maximum value VH corresponds to the first voltage in this embodiment, and the minimum value VL corresponds to the second voltage, which is different from the first voltage, in this embodiment. A drive waveform that applies a voltage in the range from VL to VH, as shown in FIG. 7A, is referred to as a first drive waveform. As an example, VH = 26 V and VL = 0 V. That is, the first drive waveform results in a maximum potential difference of 26 V.

[0064] On the other hand, Figure 7B shows a drive waveform for ejecting liquid at a potential (potential difference) between the maximum value VH and the minimum value VM of the drive voltage. The minimum value VM is greater than the minimum value VL and less than the maximum value VH. The minimum value VM corresponds to the third voltage in this embodiment. The third voltage is a voltage different from the first voltage and the second voltage. A drive waveform that applies a voltage in the range from VM to VH, as shown in Figure 7B, is referred to as a second drive waveform. As an example, VH = 26V and VL = 2V. In other words, the second drive waveform results in a maximum potential difference of 24V.

[0065] Note that the minimum value VM is not used in the first drive waveform. Similarly, the minimum value VL is not used in the second drive waveform. That is, the drive signal does not transition between three voltages and the voltages therebetween in one drive waveform, but between two voltages and the voltages therebetween. The first drive waveform and the second drive waveform are waveforms obtained by transitioning between two voltages and the voltages therebetween, and are different from each other.

[0066] In conventional technology, the maximum and minimum values ​​of the drive voltage are set in accordance with the large droplets that determine the maximum density of the image, and the waveforms of the small and medium droplets are adjusted based on the set drive voltage, resulting in a problem of limited adjustment margin for the waveforms of the small and medium droplets.

[0067] On the other hand, in this embodiment, as described above, there is provided a first drive waveform that ejects liquid by a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid by a potential difference between the first voltage and a third voltage different from the first and second voltages, and the driver IC 51 can output these drive waveforms. Therefore, compared to when droplets of multiple sizes are ejected using a single drive waveform, i.e., between one maximum and one minimum value, it is possible to prevent the adjustment margin for relatively small droplets from becoming small. This therefore increases the degree of freedom in adjusting the drive voltage for multiple types of droplets with different volumes.

[0068] In this case, the first voltage may be an adjustable voltage to change the volume of liquid ejected from the nozzle, and the third voltage may be a fixed value. For example, when adjusting the density at the site where the inkjet printer 1 is used, the ejection volume of large droplets may be increased to ensure maximum density. Therefore, assuming that large droplets are ejected using a first drive waveform and small droplets are ejected using a second drive waveform, increasing the first voltage VH widens the potential difference with the second voltage VL, thereby increasing the ejection volume of large droplets. Meanwhile, changing the first voltage VH also widens the potential difference of small droplets, increasing density across the low-density to high-density regions, resulting in a uniform change in gradation characteristics. Therefore, compared to when density increases only in the high-density region, abrupt changes in gradation characteristics can be suppressed. Note that the maximum density may also be adjusted by adjusting the ejection volume of droplets other than large droplets. The above-described techniques can be used to correct, for example, manufacturing variations in the head.

[0069] Furthermore, in the above case, by setting the third voltage VM to a fixed value that does not change, it is possible to reduce secondary problems such as the influence of residual vibration.

[0070] Furthermore, when two drive waveforms are used as described above, two potential differences can be prepared for small droplets as well, which makes it possible to expand the range (degree of freedom) of the drive voltage for small droplets, which tend to have smaller adjustment margins compared to large droplets.

[0071] As described above, the third voltage may be set to be higher than the second voltage and lower than the first voltage.

[0072] 3 does not have to be located inside the head 50. They may be located on the carriage 3, or outside the carriage 3, on the main body side of the inkjet printer 1.

[0073] Furthermore, the inkjet printer 1 according to the present embodiment described above can execute the following control methods. One of these methods is a control method for a liquid ejection recording device including a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, and a medium support unit that supports a recording medium so as to face the liquid ejection head. This method includes preparing, as drive voltages for the actuators, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage, and inputting the first drive waveform or the second drive waveform to the actuators to drive them, depending on the required volume of liquid to be ejected from the nozzles, thereby ejecting liquid from the plurality of nozzles.

[0074] Another method is a method for controlling a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, the method comprising: preparing, as drive voltages for the actuators, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first and second voltages; and ejecting liquid from the plurality of nozzles by inputting the first drive waveform or the second drive waveform to the actuators according to a required volume of liquid to be ejected from the nozzles.

[0075] The features of the ink jet printer 1 described above can constitute part of each of the above methods.

[0076] In conventional technology, a single drive waveform was generated for each ejection cycle in a single liquid ejection head (or for ejecting one color in a multi-color liquid ejection head). This drive waveform was then used in common for all ejection elements within the liquid ejection head. A temporal portion of the drive waveform was sent to each ejection element as a drive voltage. For example, a drive waveform consisting of voltage change patterns A, B, and C connected in sequence was used. The drive voltage for large droplets was the portion of the drive waveform with patterns A and C sent to the ejection elements. The drive voltage for medium droplets was the portion of the drive waveform with pattern A sent to the ejection elements. The drive voltage for small droplets was the portion of the drive waveform with pattern B sent to the ejection elements. In this conventional technology, a waveform commonly used for multiple droplet volumes was included within the drive waveform so that the ejection waveforms for multiple droplet volumes could be accommodated within a single ejection cycle. In the example described above, pattern A was commonly used for both large and medium droplets. When used in common for a plurality of droplet amounts, it is highly likely that the drive waveform will need to be finely adjusted to ensure appropriate ejection for each droplet amount.

[0077] In order to enable such drive waveform adjustment, conventional technologies have required, for example, four or more settable voltage values ​​for determining the drive waveform, or the ability to set the transition time between the set voltage values. More specifically, when transitioning from one voltage to another, it is necessary to be able to set not only the timing at which the transition begins, but also the timing at which the transition ends, and the rate of voltage change over time, etc. Such drive waveforms are generated, for example, by a driver IC, but generating the above-mentioned complex drive waveforms requires a large integrated circuit.

[0078] In this embodiment, the drive waveform is generated for each ejection element 81. Therefore, there is no need to provide a pattern like pattern A that is commonly used for multiple droplet volumes, as in the conventional technology described above. This reduces the need to finely adjust the generated drive waveform, as in the conventional technology. This also reduces the scale of the circuit that generates the drive waveform. Furthermore, by generating the drive waveform with such a small circuit scale, it is possible to provide drive signal generation units 53 in the driver IC 51 in the same number as or greater than the number of ejection elements 81, and generate a drive waveform for each ejection element 81. Specifically, this makes it possible to drive several hundred to several thousand ejection elements 81 included in the head 50.

[0079] Regarding the control of the ejection elements 81, if we only consider the drive waveform to be generated, it would be better to generate a finely adjustable drive waveform for each ejection element 81. However, if a drive signal generation unit 53 capable of finely adjusting the drive waveform is provided for several hundred to several thousand ejection elements 81, the circuit size of the driver IC 51 would become very large, resulting in extremely high costs. Furthermore, such a driver IC 51 would generate a lot of heat, making it difficult to mount on the head 50 or place near the head 50. More specifically, if the temperature of the driver IC 51 becomes too high, it could break down or frequently stop operation to prevent breakdowns. Alternatively, it would be difficult to mount a cooling device on the head 50 or place it near the head 50 to prevent the temperature from becoming too high.

[0080] The following method can be used to reduce the circuit scale of the drive signal generation unit 53. For example, the number of voltages that can be set in the drive signal generation unit 53 can be reduced. Specifically, the number of voltages that can be set is reduced to three (VH, VM, VL).

[0081] For example, the manner in which the voltage transitions between set voltages is not configurable. Specifically, for the transition between voltages, only the timing at which the transition starts is set, and the time it takes to reach the next specified voltage is determined by a time constant determined by the configured circuit, or is set to a predetermined fixed value. If the time constant is determined by the configured circuit, the circuit size can be further reduced. Note that in this embodiment, the transition of the drive voltage actually applied to the ejection element 81 is damped by a time constant determined by the electrical characteristics of the drive signal generation unit 53 and the piezoelectric element, but Figure 5 and other figures do not include this damping and are shown as a simplified rectangular wave.

[0082] For example, the number of settable voltages in one drive waveform is reduced. For example, the settable voltages are reduced to two. In this way, firstly, the number of settable voltages is simply reduced, and the circuit scale can be reduced. Furthermore, when the number of settable voltages is two, it is only necessary to configure a circuit that switches between the two voltages, that is, one voltage is used as a reference voltage and switches between an OFF state in which that voltage is applied and an ON state in which the other voltage is applied, thereby further reducing the circuit scale.

[0083] For example, while generating one drive waveform, the drive signal generation unit 53 performs ON / OFF control to determine which of two voltages (VH, VL) to apply. This makes it possible to output a drive waveform that alternates between VH and VL. Furthermore, if it is desired to make the next drive waveform a drive waveform that alternates between VH and VM, then of the two voltages VH and VL, VL is changed to VM. In this way, by performing ON / OFF control to determine which of the two voltages (VH, VM) to apply, it is possible to output a drive waveform that alternates between VH and VM.

[0084] In other words, if the drive signal generation unit 53 can switch between VM and VL as the voltage paired with VH at the boundary timing for sending two drive waveforms, it can output a drive waveform that transitions between VH and VL, and a drive waveform that transitions between VH and VM. In this way, it becomes impossible to set three voltages while outputting one drive waveform, but it is possible to generate drive waveforms with different voltage differences with a smaller circuit scale.

[0085] Next, the ejection control of large, medium and small droplets using the above two drive waveforms will be described in detail using examples.

[0086] Example 1 As an example, large droplets of liquid can be ejected using the first drive waveform of Fig. 7A, and medium and small droplets of liquid can be ejected using the second drive waveform of Fig. 7B. More specifically, ejection can be performed using the following drive waveforms. Large droplets: The waveform pattern shown in Fig. 6A (up and down voltage pattern) with the voltage change range of Fig. 7A (VL to VH). Medium droplets: The waveform pattern shown in Fig. 6B with the voltage change range of Fig. 7B (VM to VH). Small droplets: The waveform pattern shown in Fig. 6C with the voltage change range of Fig. 7B (VM to VH).

[0087] As another example, large and medium droplets of liquid can be ejected using the first drive waveform of Fig. 7A, and small droplets of liquid can be ejected using the second drive waveform of Fig. 7B. That is, large droplets can be ejected using the waveform pattern shown in Fig. 6A with the voltage change range shown in Fig. 7A, medium droplets can be ejected using the waveform pattern shown in Fig. 6B with the voltage change range shown in Fig. 7A, and small droplets can be ejected using the waveform pattern shown in Fig. 6C with the voltage change range shown in Fig. 7B.

[0088] In such cases, by applying the second drive waveform to small droplets (medium droplets), the potential difference becomes smaller than when the first drive waveform is applied, and the ejection volume can be reduced compared to when the first drive waveform is applied. Therefore, smaller droplets can be ejected, and the range of droplets can be expanded. As a result, the range of gradation expression in images can be expanded.

[0089] Example 2 When the timing of the liquid ejected from the multiple nozzles 83 to land on the workpiece W is synchronized, it becomes possible to improve the image quality. The landing timing of the liquid ejected by each waveform can be said to depend on the ejection speed. Generally, the magnitude of the liquid ejection speed based on each drive waveform has the following relationship: large droplets > medium droplets > small droplets. Furthermore, since small and medium droplets are easily decelerated by air resistance, the greater the distance from ejection to landing (print gap), the greater this relationship deviates. Note that the ejection speed is proportional to the magnitude of the drive voltage (the higher the voltage, the greater the speed).

[0090] From the above perspective, it is possible to eject medium and small droplets of liquid using the first drive waveform of Fig. 7A, and large droplets of liquid using the second drive waveform of Fig. 7B. As another example, it is possible to eject small droplets of liquid using the first drive waveform of Fig. 7A, and large and medium droplets of liquid using the second drive waveform of Fig. 7B.

[0091] 8A and 8B are schematic diagrams showing the droplet ejection state according to the drive voltage. When the first drive waveform of FIG. 7A is applied to all of the large, medium, and small droplets, the ejection speed of the large droplets is high, as shown in FIG. 8A, and the landing timing of the three types of droplets on the workpiece W becomes uneven. On the other hand, when the second drive waveform of FIG. 8B is applied to the large droplets, as in this embodiment, the ejection speed of the large droplets is reduced, making it possible to synchronize the landing timing of the three types of droplets.

[0092] As described above, in this second embodiment, the ejection speed of large droplets is reduced by applying the second drive waveform to the large droplets, and the landing timing can be synchronized with that of small droplets (medium droplets). As a result, it is possible to improve image quality.

[0093] 9 is a schematic diagram of a dual-liquid head capable of ejecting two types of liquid from a single head. For example, a head capable of ejecting two colors of ink from a single head will be described. In this case, as an example, a nozzle group ejecting black ink is arranged at one end of the head in the main scanning direction of the carriage 3, and a nozzle group ejecting yellow ink is arranged at the other end of the head in the main scanning direction. In this case, a first drive waveform and a second drive waveform can be selectively applied to adjust the voltage for each color.

[0094] For example, different ink colors have different physical properties, which can lead to different ejection conditions even with the same voltage settings. Even in such cases, the above configuration allows different drive waveforms for each color, making it possible to adjust the ejection performance for each ink and achieve stable ink ejection. In this case, two drive signal generators 53, as shown in FIG. 3, are provided for each head.

[0095] In the example of Fig. 9, the first drive waveform may be used for black ink and the second drive waveform may be used for yellow ink, thereby making it possible to provide a potential difference between the colors.

[0096] The ink jet printer 1 and its control method according to an embodiment of the present disclosure have been described above, but the present disclosure is not limited to this and can take on modified embodiments such as those described below.

[0097] Part or all of the control unit of the inkjet printer 1 may be a personal computer that sends print image information to the inkjet printer 1. The inkjet printer 1 is not limited to a configuration that can eject ink of multiple colors onto the workpiece W, and may be one that ejects ink of a single color. The inkjet printer 1 may not have the pre-treatment liquid head 5 that ejects the pre-treatment liquid, the post-treatment liquid head 6 that ejects the post-treatment liquid, or any of the components associated with these.

[0098] Although the above examples have been described using three waveforms for large, medium, and small droplets as shown in Fig. 6, fine droplet size adjustment may be performed by combining the first and second drive waveforms with a wider variety of waveforms. For example, the second drive waveform may be applied to very small droplets, the first drive waveform to small droplets, the second drive waveform to medium droplets, the second drive waveform to large droplets, and the first drive waveform to extra-large droplets.

[0099] The multiple configurations disclosed in the above embodiments can be combined with each other to form one invention.

[0100] Furthermore, in the above description, a configuration in which one ejection element 81 (actuator) is arranged corresponding to one nozzle has been described, but the present disclosure is not limited to this. A configuration in which multiple ejection elements 81 are arranged corresponding to one nozzle is also possible.

[0101] <Summary of the present disclosure> A liquid ejection head according to a first aspect of the present disclosure comprises a plurality of nozzles, a plurality of actuators corresponding to the plurality of nozzles, and a drive control unit capable of ejecting liquid from the plurality of nozzles by inputting a drive voltage to the actuators to drive the actuators, wherein the drive control unit outputs, as the drive voltage, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage.

[0102] A liquid ejection head according to a second aspect of the present disclosure is the liquid ejection head of the first aspect, wherein the first voltage is adjustable to change the volume of liquid ejected from the nozzle.

[0103] The liquid ejection head according to a third aspect of the present disclosure is the liquid ejection head of the first or second aspect, wherein the third voltage is greater than the second voltage and less than the first voltage.

[0104] A liquid ejection recording device according to a fourth aspect of the present disclosure comprises a liquid ejection head capable of ejecting liquid, having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, a medium support unit that supports a recording medium so as to face the liquid ejection head, and a drive control unit that is capable of ejecting droplets from the plurality of nozzles by inputting a drive voltage to the actuator to drive the actuator, wherein the drive control unit outputs, as the drive voltage, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage.

[0105] A fifth aspect of the present disclosure provides the liquid ejection recording apparatus of the fourth aspect, wherein the first voltage is a voltage that is adjustable to change the volume of the droplets ejected from the nozzles.

[0106] The liquid ejection recording apparatus according to a sixth aspect of the present disclosure is the liquid ejection recording apparatus of the fourth or fifth aspect, wherein the third voltage is greater than the second voltage and less than the first voltage.

[0107] A seventh aspect of the present disclosure provides a method for controlling a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, comprising: preparing, as drive voltages for the actuators, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage; and inputting the first drive waveform or the second drive waveform into the actuator to drive the actuator according to the required volume of liquid to be ejected from the nozzles, thereby ejecting liquid from the plurality of nozzles.

[0108] An eighth aspect of the present disclosure provides a method for controlling a liquid ejection head according to the seventh aspect, wherein the first voltage is a voltage that is adjustable to change the volume of liquid ejected from the nozzle.

[0109] A ninth aspect of the present disclosure provides a liquid ejection head control method according to the seventh or eighth aspect, wherein the third voltage is greater than the second voltage and less than the first voltage.

[0110] A control method for a liquid ejection recording device according to a tenth aspect of the present disclosure is a control method for a liquid ejection recording device including a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, and a medium support unit that supports a recording medium so as to face the liquid ejection head, the control method comprising: preparing, as drive voltages for the actuator, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage; and inputting the first drive waveform or the second drive waveform into the actuator to drive the actuator depending on the required volume of liquid to be ejected from the nozzle, thereby ejecting liquid from the plurality of nozzles.

[0111] A control method for a liquid ejection recording apparatus according to an eleventh aspect of the present disclosure is the tenth aspect, wherein the first voltage is a voltage that is adjustable to change the volume of liquid ejected from the nozzle.

[0112] A method for controlling a liquid ejection recording apparatus according to a twelfth aspect of the present disclosure is the method of controlling a liquid ejection recording apparatus according to the tenth or eleventh aspect, wherein the third voltage is greater than the second voltage and less than the first voltage.

[0113] According to the above disclosures, compared to when droplets of multiple sizes are ejected using a single drive waveform, i.e., between a single maximum value and a single minimum value, it is possible to prevent the adjustment margin for relatively small droplets from becoming too small, thereby increasing the degree of freedom in adjusting the drive voltage for multiple types of droplets with different volumes.

[0114] In the above-described configuration or method, the first voltage may be a voltage that is adjustable to change the volume of the liquid ejected from the nozzle, and the third voltage may be a fixed value.

[0115] In the above-described configuration or method, the third voltage may be greater than the second voltage and less than the first voltage.

[0116] REFERENCE SIGNS LIST 1 Inkjet printer (liquid ejection recording device) 3 Carriage 4 Ink head 5 Pre-treatment liquid head 6 Post-treatment liquid head 20 Work transport unit 21 Drive roller 22 Driven roller 50 Head (liquid ejection head) 51 Driver IC (drive control unit) 52 Head control unit 53 Drive signal generation unit 80 Nozzle unit 81 Ejection element (actuator) 82 Liquid pressure chamber 83 Nozzle

Claims

1. A liquid ejection head comprising: a plurality of nozzles; a plurality of actuators corresponding to the plurality of nozzles; and a drive control unit capable of ejecting liquid from the plurality of nozzles by inputting drive voltages to the actuators to drive the actuators, wherein the drive control unit outputs, as the drive voltages, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage; and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage.

2. A liquid ejection head according to claim 1, wherein the first voltage is adjustable to vary the volume of liquid ejected from the nozzle.

3. A liquid ejection head according to claim 1 or 2, wherein the third voltage is greater than the second voltage and less than the first voltage.

4. A liquid ejection recording device comprising: a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles and capable of ejecting liquid; a medium support section that supports a recording medium so as to face the liquid ejection head; and a drive control section that is capable of inputting a drive voltage to the actuator to drive the actuator, thereby causing droplets to be ejected from the plurality of nozzles, wherein the drive control section outputs, as the drive voltage, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage.

5. A liquid ejection recording apparatus according to claim 4, wherein the first voltage is a voltage that is adjustable to change the volume of the droplets ejected from the nozzles.

6. A liquid discharge recording apparatus according to claim 4 or 5, wherein the third voltage is higher than the second voltage and lower than the first voltage.

7. A method for controlling a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, comprising: preparing, as drive voltages for the actuators, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage; and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage; and inputting the first drive waveform or the second drive waveform into the actuators to drive the actuators according to the required volume of liquid to be ejected from the nozzles, thereby ejecting liquid from the plurality of nozzles.

8. The method for controlling a liquid ejection head according to claim 7, wherein the first voltage is a voltage that can be adjusted to change the volume of liquid ejected from the nozzle.

9. The method for controlling a liquid ejection head according to claim 7 or 8, wherein the third voltage is greater than the second voltage and less than the first voltage.

10. A control method for a liquid ejection recording device including a liquid ejection head having a plurality of nozzles and a plurality of actuators corresponding to the plurality of nozzles, and a medium support unit that supports a recording medium so as to face the liquid ejection head, comprising: preparing, as drive voltages for the actuator, a first drive waveform that ejects liquid with a potential difference between a first voltage and a second voltage different from the first voltage, and a second drive waveform that ejects liquid with a potential difference between the first voltage and a third voltage different from the first voltage and the second voltage; and inputting the first drive waveform or the second drive waveform into the actuator to drive the actuator according to the required volume of liquid to be ejected from the nozzle, thereby ejecting liquid from the plurality of nozzles.

11. The method for controlling a liquid ejection recording apparatus according to claim 10, wherein the first voltage is a voltage that can be adjusted to change the volume of liquid ejected from the nozzle.

12. The method for controlling a liquid discharge recording apparatus according to claim 10 or 11, wherein the third voltage is higher than the second voltage and lower than the first voltage.

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